차세대 액정 디스플레이용 광시야각 및 칼라구현 기술에 관한 연구

학위논문 (박사)-- 서울대학교 대학원 공과대학 전기·컴퓨터공학부, 2017. 8. 이신두.In the past decades, liquid crystal display (LCDs) have been extensively studied for use in flat panel displays (FPDs) because of light weight panel, thin thickness and low power consumption. Due to their high contrast, uniform brightness, and rapid switching times compared to conventional cathode ray tubes, LCDs have achieved a significant position in the FPD industry. However, according to the development of other FPD technologies including organic light-emitting didoes, the enhancement of LCD performances such as wide-viewing angle and vivid coloration has been demanded. In this thesis, novel image generation technologies for high performance LCD are proposed. At first, for the reduction of the gamma distortion, wide-viewing technology was demonstrated by sophisticated multi-domain configuration in which liquid crystal (LC) molecules are aligned along different polar directions at middle gray scale. In order to realize the multi-domain LC cell, a new alignment layer which can control polar LC alignment properties including the pretilt angle and the anchoring energy was developed. Uncured hydrophobic oligomers in a cross-linked polymer mold were transferred onto a substrate to change the surface wettability of the substrate. The thermal-transfer printing, which is a contact-transfer printing method including an additional heat treatment process, accelerated the molecular diffusion of oligomers from the polymer mold onto the substrate, resulting in the increase of the amount of transferred oligomer. Consequently, the surface energy of the substrate was manipulated according to the heat treatment temperature during the thermal-transfer printing. Then, the LC alignment properties in both azimuthal and polar directions were measured through LC cell fabrication and electro-optical characterization. It was found that the polar pretilt angle and polar anchoring energy were changed in a wide-range, resulting from the adjustment of the substrate surface energy. Based on the results described above, the reduction of the gamma distortion through the multi-domain configuration in the vertical alignment (VA) mode was demonstrated. The oligomer layer was formed onto a conventional VA alignment layer to control the polar alignment properties. The ultra-violet ozone (UVO) treatment for the enhancement of the oligomer transfer onto hydrophobic substrates was added in the fabrication process. The surface energy and anchoring energy of the stacked alignment layers depending on the UVO treatment was examined. The anchoring disparity, which is the anchoring energy difference between sub-domains as a result of the oligomer layer patterning, induced the threshold voltage difference in the sub-domains and constructed the multi-domain at applied voltages. The experimental measurements for the assessment of the gamma distortion were performed in a conventional patterned VA mode cell and proposed multi-domain cell. Next, for the expansion of the color space, a new type of coloration technique based on the photo-luminescent emission of the quantum dots (QDs) in an organic polymer matrix was described. Recently, QD patterning technologies based on the polymer matrix have been extensively studied to accurately express the primary color in pixel units, but suffered from the non-uniform light emission owing to uneven distribution of the QDs in the polymer matrix. Reactive mesogen (RM), which is photo-curable, transparent, and soluble in organic solvents, was used for the fabrication of uniformly distributed QDs in the RM matrix. The emission characteristics of QD-RM composites depending on the concentration ratios of QD and RM were examined. In addition, color-separated patterns of QD-RM composites on a single substrate through conventional photo-lithography processes were demonstrated. Finally, a novel QD emissive LCD based on the color-separated pattern for high color purity was proposed. The proposed LCD consists of modulation part and emission part. LC cells acts as a role of electrically tunable lightwave retarder depending on the applied voltage. The transmitted light through the modulation part emits the photo-luminescent light from the color-separated QD pattern. The color purity and color gamut of the QD emissive LCD was measured in comparison with previous LCDs such as the color filter LCD and QD compensated LCD. In conclusion, the applicability of proposed image generation technologies to the FPD industry was explored. The new concepts and experimental results will lead to the development of the advanced LCD performance.Chapter 1 Introduction 1 1.1 Overview of Flat Panel Displays 1 1.2 Outline of Thesis 9 Chapter 2 Emerging Technologies of Liquid Crystal Display 13 2.1 Operating Principles of LCD 13 2.1.1 Properties of LCs 14 2.1.2 Main LCD modes 21 2.2 Wide-Viewing Angle Technologies 28 2.2.1 General description of viewing properties 28 2.2.2 Recent technologies for wide-viewing 35 2.3 Coloration Technologies 43 2.3.1 Coloration in flat panel displays 43 2.3.2 Recent technologies for wide color gamut 52 Chapter 3 Enhancement of Viewing Angle of LCD by Multi-Domain 65 3.1 Control of Molecular Alignment by Thermo-Transfer Printing 65 3.1.1 Introduction 66 3.1.2 Thermo-transfer printing for surface modification 67 3.1.3 Fabrication process 69 3.1.4 Experimental results and discussions 72 3.1.5 Summary 83 3.2 Wide-Viewing by Anchoring Disparity 85 3.2.1 Introduction 85 3.2.2 Anchoring disparity by thermo-transfer printing 86 3.2.3 Fabrication of 8-domains 95 3.2.4 Experimental results and discussions 98 3.2.5 Summary 100 Chapter 4 Novel Quantum Dot-Based LCD for High Color Purity 101 4.1 Color-Separated Pattern of QDs 101 4.1.1 Introduction 101 4.1.2 Fabrication of color-separated QD patterns 103 4.1.3 Experimental results and discussions 105 4.2 QD Emissive LCD 109 4.2.1 Device concept 109 4.2.2 Fabrication of QD-based LCD 110 4.2.3 Experimental result and discussions 111 4.2.4 Summary 118 Chapter 5 Concluding Remarks 119 Bibliography 123 Publication 135 국문 초록 141Docto

Robust Localization and Efficient Path Planning for Mobile Sensor Networks

학위논문 (박사)-- 서울대학교 대학원 : 전기·컴퓨터공학부, 2016. 2. 오성회.The area of wireless sensor networks has flourished over the past decade due to advances in micro-electro-mechanical sensors, low power communication and computing protocols, and embedded microprocessors. Recently, there has been a growing interest in mobile sensor networks, along with the development of robotics, and mobile sensor networks have enabled networked sensing system to solve the challenging issues of wireless sensor networks by adding mobility into many different applications of wireless sensor networks. Nonetheless, there are many challenges to be addressed in mobile sensor networks. Among these, the estimation for the exact location is perhaps the most important to obtain high fidelity of the sensory information. Moreover, planning should be required to send the mobile sensors to sensing location considering the region of interest, prior to sensor placements. These are the fundamental problems in realizing mobile sensor networks which is capable of performing monitoring mission in unstructured and dynamic environment. In this dissertation, we take an advantage of mobility which mobile sensor networks possess and develop localization and path planning algorithms suitable for mobile sensor networks. We also design coverage control strategy using resource-constrained mobile sensors by taking advantages of the proposed path planning method. The dissertation starts with the localization problem, one of the fundamental issue in mobile sensor networks. Although global positioning system (GPS) can perform relatively accurate localization, it is not feasible in many situations, especially indoor environment and costs a tremendous amount in deploying all robots equipped with GPS sensors. Thus we develop the indoor localization system suitable for mobile sensor networks using inexpensive robot platform. We focus on the technique that relies primarily on the camera sensor. Since it costs less than other sensors, all mobile robots can be easily equipped with cameras. In this dissertation, we demonstrate that the proposed method is suitable for mobile sensor networks requiring an inexpensive off-the-shelf robotic platform, by showing that it provides consistently robust location information for low-cost noisy sensors. We also focus on another fundamental issue of mobile sensor networks which is a path planning problem in order to deploy mobile sensors in specific locations. Unlike the traditional planning methods, we present an efficient cost-aware planning method suitable for mobile sensor networks by considering the given environment, where it has environmental parameters such as temperature, humidity, chemical concentration, stealthiness and elevation. A global stochastic optimization method is used to improve the efficiency of the sampling based planning algorithm. This dissertation presents the first approach of sampling based planning using global tree extension. Based on the proposed planning method, we also presents a general framework for modeling a coverage control system consisting of multiple robots with resource constraints suitable for mobile sensor networks. We describe the optimal informative planning methods which deal with maximization problem with constraints using global stochastic optimization method. In addition, we describe how to find trajectories for multiple robots efficiently to estimate the environmental field using information obtained from all robots.Chapter 1 Introduction 1 1.1 Mobile Sensor networks 1 1.1.1 Challenges 3 1.2 Overview of the Dissertation 4 Chapter 2 Background 7 2.1 Localization in MSNs 7 2.2 Path planning in MSNs 10 2.3 Informative path planning in MSNs 12 Chapter 3 Robust Indoor Localization 15 3.1 An Overview of Coordinated Multi-Robot Localization 16 3.2 Multi-Robot Localization using Multi-View Geometry 19 3.2.1 Planar Homography for Robot Localization 20 3.2.2 Image Based Robot Control 21 3.3 Multi-Robot Navigation System 25 3.3.1 Multi-Robot System 26 3.3.2 Multi-Robot Navigation 30 3.4 Experimental Results 32 3.4.1 Coordinated Multi-Robot Localization: Single-Step 32 3.4.2 Coordinated Multi-Robot Localization: Multi-Step 36 3.5 Discussions and Comparison to Leap-Frog 42 3.5.1 Discussions 42 3.5.2 Comparison to Leap-Frog 45 3.6 Summary 51 Chapter 4 Preliminaries to Cost-Aware Path Planning 53 4.1 Related works 54 4.2 Sampling based path planning 56 4.3 Cross entropy method 59 4.3.1 Cross entropy based path planning 63 Chapter 5 Fast Cost-Aware Path Planning using Stochastic Optimization 65 5.1 Problem formulation 66 5.2 Issues with sampling-based path planning for complex terrains or high dimensional spaces 68 5.3 Cost-Aware path planning (CAPP) 73 5.3.1 CE Extend 75 5.4 Analysis of CAPP 81 5.4.1 Probabilistic Completeness 81 5.4.2 Asymptotic optimality 83 5.5 Simulation and experimental results 84 5.5.1 (P1) Cost-Aware Navigation in 2D 85 5.5.2 (P2) Complex Terrain Navigation 88 5.5.3 (P3) Humanoid Motion Planning 96 5.6 Summary 103 Chapter 6 Effcient Informative Path Planning 105 6.1 Problem formulation 106 6.2 Cost-Aware informative path planning (CAIPP) 109 6.2.1 Overall procedure 110 6.2.2 Update Bound 112 6.2.3 CE Estimate 115 6.3 Analysis of CAIPP 118 6.4 Simulation and experimental results 120 6.4.1 Single robot informative path planning 120 6.4.2 Multi robot informative path planning 122 6.5 Summary 125 Chapter 7 Conclusion and Future Work 129 Appendices 131 Appendix A Proof of Theorem 1 133 Appendix B Proof of Theorem 2 135 Appendix C Proof of Theorem 3 137 Appendix D Proof of Theorem 4 139 Appendix E Dubins' curve 141 Bibliography 147 초 록 163Docto

Survival and Recurrence Pattern after Curative Resection of Pancreatic Cancer

Background/Aims: The only hope for the cure of pancreatic adenocarcinoma is curative resection. However, the rate of recurrence after curative resection is higher than 50%. The aim, of this study were to analyze survival and the factors influencing survival and to evaluate the recurrence rate and pattern after curative resection of pancreatic adenocarcinoma. Methods: The records of 250 patients who were diagnosed as pancreatic cancer were reviewed retrospectively. We classified the patients into 3 groups (curative resection, non-curative resection, and conservative treatment) and analyzed the factors influencing survival, recurrence rate, and recurrence pattern after curative resection. Results: Curative resection were performed in 31 (12.4%) of 250 cases. The patients with curative resection was significantly prolonged median survival time than those without non-curative resection or with conservative treatment. The factors influencing survival rate after curative resection were age, lymph node involvement, and disease status. Twenty-five of the 31 cases with curative resection had recurrences after 10 months. Local retroperitoneal recurrence was 69%. Liver metastasis and lymph node metastasis were occurred in 61% and 54%, respectively. Conclusions: The survival time of the patients with pancreatic adenocarcinoma was prolonged in the cases of curative resection compared with the cases of non-curative resection or conservative treatment. However, most cases after curative resection showed recurrence. Thus, early diagnosis and early treatment should be needed to prolong the survival time of the patients with pancreatic adenocarcinoma.ope

광화 유체 내의 구리 동위원소에 대한 양자 화학 계산

Thesis(master`s)--서울대학교 대학원 :지구환경과학부,2007.Maste

A Feature-Based Approach to Operational Model Validation in Software Requirements Engineering

Maste

위상최적화 설계물의 복잡도 조절

Thesis (master`s)--서울대학교 대학원 :기계항공공학부,2003.Maste

Causes of chronic cough, assessed by esophageal manometry and 24 hour esophageal pH monitoring

의학과/석사[한글] 3주 이상 지속되는 만성기침은 대중치료에 잘 호전되지 않아 정확한 원인 진단과 치료가 필요하다. 만성기침의 원인은 후비루, 기관지천식, 위식도역류질환, 만성기관지염의 순으로 이들이 전체의 90%이상을 차지한다. 이 중 위식도역류질환은 세 번째로 흔한 원인으로 약 10-21%를 차지하며 이와 연관된 만성기침의 치료율은 80-100%로 보고되고 있다. 그러나 기존의 연구들은 해부학적 진단체계에 따른 순차적인 진단방법으로 만성기침의 원인을 조사하여 정확한 조사가 이루어졌다고 보기 어렵다. 또한 만성기침환자에서 식도운동장애나 식도산청소능장애의 빈도와 이들의 역할에 대한 연구는 많지 않은 실정이다. 이에 본 연구는 만성기침 환자에서 병력조사, 신체검진과 각종 검사를 동시에 실시하여 원인별 빈도와 이들을 치료했을 때의 효과를 알아보았다. 그리고 만성기침 환자에서 위식도역류질환, 식도운동성질환과 식도산청소능장애의 빈도와 이들의 역할을 알아보았고 위식도역류질환과 연관된 만성기침의 진단에 있어서 보행성24시간식도산도검사와 식도내압검사의 유용성을 알아보았다. 또한 위식도역류질환이 기침의 원인인 군과 그 외의 질환이 원인인 군간의 임상적 차이를 비교하였다. 1998년 5월부터 1999년 7월까지 연세대학교 의과대학 세브란스병원에 만성기침을 주소로 내원한 환자 중 식도내압검사와 보행성24시간식도산도검사를 시행한 36명의 환자들을 대상으로 병력조사와 문진, 신체검사, 알레르기검사, 방사선학적검사, 상부위장관내시경검사, 보행성24시간식도산도검사, 식도내압검사와 식도산청소능검사를 시행하였고 같은 시기에 비심인성 흉통으로 내원한 38명의 환자와 인두종괴감(globushystericus)으로 내원한 28명의 환자를 대상으로 보행성24시간식도산도검사와 식도내압검사를 시행하였다. 만성기침 환자의 평균연령은 46.1±14세였고 남녀비는 1:1.8이었다. 방문전 증상 기간의 중간값은 16주(13주-1920주)였고 평균 추적관찰 기간은 17.4±6.5주였다. 만성기침의 원인별 빈도는 치료전 진단 시 후비루가 55.6%, 위식도역류질환이 44.4%, 기관지천식이 16.8%로 이들이 차지하는 비율이 전체의 77.8%였고 두 가지 이상의 원인이 같이 있었던 경우는 33.9%였다. 만성기침 환자에서 식도내압검사로 평가한 식도운동성질환은 27.8%였고 이중 비특이성 식도운동장애가 가장 많았으며 식도산청소능장애는 26.9%였다. 만성기침 환자, 비심인성흥통 환자와 인두종괴감 환자의 위식도역류질환과 식도운동성질환의 빈도는 유의한 차이가 없었다. 치료전 진단에 따른 만성기침 환자의 치료 반웅은 88.3%였고 위식도역류질환의 치료시 87.6%의 환자에서 기침의 호전을 보였다. 치료 반응에 따른 치료후 진단의 원인별 빈도는 후비루가 50%, 위식도역류질환이 38.9%, 기관지천식이 16.8%로 이들이 차지하는 비율이 75%였고 두 가지 이상의 원인이 같이 있었던 경우는 27.8%였다. 치료후 진단에 따른 치료 반응율은 전체적으로 94.1%였고 위식도역류질환에 의한 만성기침에서는 100%의 호전을 보였다. 위식도역류질환에 의한 만성기침의 진단에 있어서 보행성24시간식도산도검사는 87.5%의 민감도, 100%의 특이도, 100%의 양성예측도, 90.9%의 음성예측도와 94.4%의 정확도를 보였고 식도내압검사는 진단적 유용성이 없었다. 위식도역류질환이 만성기침의 원인인 군과 그 외의 질환이 훤인인 군간의 임상적 차이를 비교해 보면 위식도역류질환군이 그 외의 질환이 원인인군에 비해 남성이 많았고 높은 체질량지수(body mass index)를 보였으나 기침이 자주 발생하는 시간, 자세나 식사와의 연관성, 연령과 증상의 기간 등은 양군간에 유의한 차이가 없었다. 또한 양군간에 식도운동장애와 식도산청소능장애의 빈도에 있어서도 유의한 차이가 없었다. 이상의 결과로 만성기침의 원인은 후비루, 위식도역류질환, 기관지천식과 만성기관지염이 대부분을 차지하므로 만성기침의 원인을 진단할때 이들에 대한 조사가 선행되어야 하고 두 가지 이상의 원인이 같이 있었던 경우도 상당수 있으므로 한가지 진단과 치료에 효과가 적거나 없을 때 다른 동반 원인을 찾아보는 것도 필요하다고 생각한다. 위식도역류질환의 빈도가 후비루 다음으로 높아 이에 대한 적극적인 진단과치료가 필요하며 보행성24시간식도산도검사가 위식도역류질환과 연관된만성기침을 진단하는 가장 유용한 방법이므로 만성기침 환자에서 이에 대한 검사가 고려되어야겠다. 위식도역류질환을 포함한 만성기침의 원인들은 높은 치료 성공율을 보였다. 위식도역류질환과 식도운동장애의빈도는 만성기침 환자, 비심인성흥통 환자와 인두종괴감 환자에서 유의한 차이가 없었으나 향후 정상 대조군과의 비교 조사가 있어야겠다. 만성기침 환자에서 식도운동장애와 식도산청소능장애의 빈도는 위식도역류군과 그 외의 질환이 원인인 군에서 유의한 차이를 보이지 않아 위식도역류질환과 연관된 만성기침에서 이들의 역할은 명확하지가 않았고 향후 만성기침 환자에서 식도운동장애와 식도산청소능장애의 역할에 대한 보다 많은 연구가 이루어져야 한다고 생각한다. [영문] Chronic cough, being defined as the presence of cough for atleast 3 weeks, does not respond to symptomatic treatment, and more accurate diagnosis of the underlying cause and specific treatment are needed. Utilizing a diagnostic protocol based on the anatomy of the cough reflex, postnasal drip, asthma, gastroesophageal reflux disease(GERD), and chronic bronchitis were common causes of chronic cough, together accounting for more than 90% of cases. GERD is the third common cause of chronic cough in up to 21% of patients. Therapeutic response rates for chronic cough associated with GERD range from 80% to 100%. There were few studies about the incidence and role of esophageal motility disorder and delayed esophageal acid clearance in chronic cough. So we evaluated the causes of chronic cough and their therapeutic response rates. We also evaluated the incidence and role of GERD, esophageal motility disorder, and delayed esophageal acid clearance among chronic cough patients, as well as the role of 24-hour ambulatory pH monitoring and esophageal manometry in the diagnosis of GERD-related chronic cough. 36 patients complaining of chronic cough were enrolled and diagnosis was made by history, physical examination, allergic test, radiologic test, esophagoscopy, 24-hour ambulatory esophageal pH monitoring, esophageal manometry, and esophageal acid clearance test. As control groups, 38 patients with noncardiogenic chest pain(NCCP) and 28 patients with globes hystericus received 24-hour ambulatory esophageal pH monitoring and esophageal manometry. Chronic cough was due to one condition in 72,2% and two or more in 27.8%. The spectrum and frequency of chronic cough were found to be postnasal drip (50%), GERD (38.9%), asthma (16.7%), and together accounting for 75% of causes. Therapeutic response rate was 94.1% overall and 100% in GERD-related cough. The frequencies of esophageal motility disorder and delayed esophageal acid clearance were 27.8% and 26.9%, respectively. The frequencies of GERD and esophageal motility disorder in chronic cough, NCCP, and globus hystericus were not different significantly. 24-hour ambulatory pH monitoring had good sensitivity (87.5%), specificity(100%), positive predictive value (100%), negative predictive value(90.9%), and accuracy (94.4%) in identifying GERD-related cough. GERD-related cough revealed significantly higher proportion of males and higher BMI than other causes of cough, but there were no significant differences between two groups for the timing of cough, cough-related posture, the association of cough with meal, age, and the duration of symptom. In conclusion, chronic cough was most commonly caused by postnasal drip, followed by GERD, asthma, and chronic bronchitis, so these causes should be evaluated first. Because chronic cough was caused by multiple disorders in some patients, when certain patients show no response or partial response with single diagnosis and treatment, it is necessary to find other possible causes. Because the frequency of GERD was the second most common cause, next to postnasal drip, active diagnosis and management of GERD are required. 24 hour ambulatory pH monitoring should be considered for chronic cough patient, since it was the most efficient method to diagnose GERD in them, Even though there were no differences of the frequency of GERD and esophageal motility disorder among the patients with chronic cough, non-cardiogenic chest pain, and globus hystericus, further studies comparing chronic cough patients with normal control should be carried out. In patients with chronic cough, the frequency of esohphageal motility disorder and esophageal acid clearance disorder were not different among GERD group and other etiology groups, and the role of these disorders were not clear The role of esophageal motility disorder and delayed esophageal acid clearance in chronic cough should be studied further more.ope

고분자 전해질막 연료전지 가스확산층의 이방성에 따른 성능 및 열화특성에 관한 연구

학위논문 (박사)-- 서울대학교 대학원 : 기계항공공학부, 2013. 8. 김민수.고분자 전해질 막 연료전지에서 가스확산층은 촉매층으로의 반응가스 이송, 전자의 전도, 촉매층에서 생성된 포화액의 원활한 배출, 그리고 연료전지 구성품의 체결시 기계적으로 막전극 접합체를 기계적으로 지지해주는 역할을 한다. 가스확산층을 제작할 때에 그 특성상 기계적 평면이방성을 가진다. 본 연구에서는 연료전지 주 유로에 평행하게 배치하여 조립되는 경우를 0도, 반대로 수직하게 배치하여 조립되는 경우를 90도 가스확산층으로 각각 정하였다. 연료전지가 조립될 때 가스확산층의 변형 혹은 유로측으로의 투과는 일어날 수 밖에 없는 현상으로 이러한 변형 및 투과성을 최소화 하는 것이 연료전지 성능을 향상시키는 중요한 요인이 된다. 따라서, 가스확산층의 평면 이방성에 따른 기계적 강성의 차이가 연료전지 체결시에 발생하는 변형 및 투과에 미치는 영향을 분석하고 최종적으로 성능 및 내구성에 미치는 영향을 실험 및 모델을 통해 분석하였다. 먼저 가스 확산층의 평면이방성에 따른 연료전지 성능 및 분리판의 기하구조에 따른 경향을 분석하기 위하여 유로의 채널부와 랜드부의 비에 따라서, 그리고 채널부의 깊이에 따라 각각 3개씩의 분리판을 제작하였다. 90도 가스확산층을 사용하는 연료전지가 0도 가스확산층을 사용하는 경우보다 모든 조건에서 성능이 높게 나왔으며 이는 연료전지 체결시 90도 가스확산층의 높은 기계적 강도에 따른 것으로 분석되었다. 또한, 분리판의 채널/랜드부의 비가 감소할수록 90도와 0도를 사용하는 연료전지의 성능과 고주파저항의 차가 더 크게 나타났으며 이는 랜드부의 비가 감소할수록 가스확산층이 변형 및 침투되는 경향이 강하게 나타나기 때문으로 분석된다. 그리고 유로의 깊이의 증가에 따라서는 공기의 압력저하가 유로 깊이의 증가로 인하여 감소하므로 전반적으로 성능이 증가하였다. 다음으로 연료전지 유로의 랜드부 아래 가스확산층의 반응가스의 투과성이 성능에 미치는 영향을 분석하기 위한 해석을 수행하였다. 가스확산층의 이방성을 모사하기 위하여 가스 투과도를 측정하는 장치를 제작하여 90도와 0도의 가스 투과도를 측정하였다. 그 결과 90도 가스확산층의 투과도가 0도의 경우보다 높게 나왔으며 측정된 값은 모델에 적용하였다. 모델을 수행한 결과, 90도 가스확산층의 경우 유로의 랜드부 아래에서 보다 높은 투과가 발생하였으며 고전류밀도에서 더욱 그 차이가 높게 나타났다. 마지막으로 고분자 전해질 막의 반복적인 팽창과 수축으로 인한 막전극 접합체 및 가스확산층의 내구성에 미치는 영향을 분석하기 위하여 습/건조 공기를 반복적으로 주입하는 가속화 실험을 수행하였다. 3000회 반복 실험 결과 0도 가스확산층을 사용한 연료전지의 성능이 90도 가스확산층을 사용한 경우에 비해 성능 감소가 더욱확연히 나타났다. 또한 고주파 저항 및 크로스오버에서도 0도 가스확산층의 경우 그 증가율이 높게 나타났다. 이는 주사형 전자현미경을 사용하여 촬영된 이미지를 통해 검증되었다. 이러한 분석결과는 가스확산층의 평면이방성의 적용 및 분리판의 최적 설계를 통하여 성능을 보다 향상 시킬 수 있을 뿐만 아니라, 내구성의 향상을 통하여 연료전지 시스템의 상용화를 앞당기기 위한 핵심 자료로써 활용 될 수 있을 것으로 기대한다.Gas diffusion layers (GDLs) play important roles that include reactant gas transportation, electron conduction, liquid water management and structural supporting of membrane electrode assembly (MEA) in polymer electrolyte membrane fuel cells (PEMFCs). The macro-porous layer has anisotropic characteristics by preferential direction of mechanical properties. The in-plane anisotropy of GDL has both fiber directions that is perpendicular (designated by 90° GDL) and parallel (designated by 0° GDL) to the major flow when fuel cell components are assembled. Deformation and intrusion into the cell channel of GDL are inevitable during the cell assembly. Mechanical bending stiffness direction by the in-plane anisotropy can influence on the GDL deformation/intrusion and accordingly, the cell performance and durability. For analyzing clearly the effects of the GDL in-plane anisotropy, experimental and numerical studies are conducted. Firstly, the effects of GDL in-plane anisotropy on cell performance were investigated experimentally. For analyzing correlation between anisotropic bending stiffness of a GDL and geometries of bipolar plates, 6 bipolar plates having 3 different channel/land width ratios and 3 different channel depths are prepared. I-V performance of the fuel cells with 90° GDL are generally higher than those with 90° GDL. On the contrary, high-frequency resistance (HFR) of the fuel cells with 90° GDL is lower than those with 0° GDL due to the higher resistance to force of bipolar plates during fuel cell assembly. In experimental results by different channel/land width ratios, the differences of I-V performances and HFR values between 90° and 0° GDL cells gradually decrease with increasing land/channel width ratio. It is because that anisotropic stiffness effect of the GDLs with wider land is reduced due to the better support. Therefore, less deformation and intrusion into channel of fuel cells with 90° GDL can improve the fuel cell performance. Air pressure drop of all the fuel cells with 90° GDLs was similar to those with 0° GDLs because air flow in channel at sufficient wide channel height of 0.6 mm. The cross-sectional images of GDLs upon compression pressure support the results by 90° GDLs have less deformation. In experimental results by different channel depths, the differences of air pressure drop values between the 90° and 0° GDL cells were appeared. In shallowest channel, the air pressure drop values of the 0° GDL cells were clearly higher than those of the 90° GDL cells due to more intrusion of 0° GDL into the channel. However, other channels except the shallowest channel appear no significant difference presumably due to the exceptional increase in the air pressure may cause more deformation and poor contact status of the GDLs in the fuel cell. In dead-end mode, the peak voltage of the 0° GDL cell was also higher than 90° GDL indicating the higher contact resistance in 0° GDL cell. Also, the purge interval of the fuel cell with 0° GDL was also longer than that of the fuel cell with 90° GDL implying the difference of GDL porosity reduction between both to 90° and 0° GDL cells at same cell assembly pressure. The averaged voltages of 90° GDL cell were higher than those of 0° GDL cell and the difference is more obvious at higher current density owing to the higher contact resistance in the higher current density. Numerical model using commercial computational fluid dynamics (CFD) was conducted for analyzing the effect of anisotropic GDLs on cell performance by gas permeation through the cell channel. Permeability of anisotropic GDLs for applying to model simulation was measured. Afterwards, same geometry as single cell used in chapter 3 was applied in this model. The voltage difference in high current density over 0.9 A/cm2 was relatively distinct, whereas the voltage difference in low current density below 0.9 A/cm2 was negligible. The simulation results show that the higher performance was induced by gas permeation through the cell channels. By the result, it is identified that not only contact resistance by GDL deformation but also gas permeation through the cell channel influence on the cell performance. Lastly, the effect of in-plane anisotropic characteristics on the mechanical degradation of an MEA was investigated using an AST. The wet/dry cycling method was adopted to cause mechanical degradation of the MEA. I–V performances and HFRs of the 90° GDL cell and 0° GDL cell were measured every 500 cycles and hydrogen crossover rates were measured every 1000 cycles. I–V performance and HRF drop of the 0° GDL fuel cell according to wet/dry cycles was higher because the 0° GDL had lower resistance to stress by repetitive membrane swelling/shrinkage than the 90° GDL. The increase in the hydrogen crossover rate of the 0° GDL fuel cell was higher than that of the 90° GDL fuel cell because of mechanical degradation of the MEA. Through SEM, it was shown that the MEA deformation of 0° GDL fuel cells was more severe than that of the 90° GDL fuel cell after wet/dry cycles. No spatial gap due to deformation of the 90° GDL under compression was detectedhowever, a gap for the 0° GDL was observed. These results support our assumptions that a higher resistance of the GDL to repetitive membrane swelling/shrinkage by wet/dry cycles increases the performance and durability of the fuel cell. It was identified that cell performance can be improved by simple adjustment of GDL arrangement during cell assembly. The results about the effects by geometry of bipolar plates can be helpful for optimum designs of fuel cell components. Also, this effort to minimize the GDL deformation and degradation will bring forward the commercialization of PEMFC.Abstract ii Contents vi List of Figures ix List of Tables xvii Nomenclature xviii Chapter 1. Introduction 14 1.1 Background of the study 14 1.2 Literature survey 17 1.3 Objectives and scopes 23 Chapter 2. Experimental apparatus and method 25 2.1 Introduction 25 2.2 Single fuel cell 25 2.3 Experimental apparatus and test conditions 27 Chapter 3. Cell performances by GDL anisotropic characteristic 33 3.1 Introduction 33 3.2 Performance tests in open mode fuel cell 35 3.2.1 I-V performances 35 3.2.2 High frequency resistance 41 3.2.3 Pressure differences 52 3.2.4 Electrical resistances of bipolar plates 59 3.3 Performance test in cathodic dead-end mode fuel cell 63 3.3.1 Methods for experiments 64 3.3.2 Purge characteristics by GDL anisotropy 66 3.4 Summary 74 Chapter 4. Theoretical analysis on GDL anistropic characteristics 77 4.1 Introduction 77 4.2 Experiment for measuring the GDL permeability 78 4.2.1 Experiment setup 78 4.2.2 Measurement or permeability 84 4.3 Mesh generation and model coditions 89 4.3.1 Model assumptions 89 4.3.2 Governing equations 90 4.4 Results and discussion 98 4.5 Summary 101 Chapter 5. Effects of GDL anisotropy on fuel cell degradation 105 5.1 Introduction 105 5.2 Accelerated stresses test method 107 5.2.1 Experimental setup 107 5.2.2 Accelerated stress test method 109 5.3 Differences of mechanical degradation by GDL anisotropy during wet/dry cycles 110 5.3.1 I-V performances 111 5.3.2 HFR measurements 113 5.3.3 Hydrogen crossover rate through the membrane 119 5.3.4 Morphology of MEA 120 5.4 Summary 125 Chapter 6. Concluding remarks 128 References 133 Abstract (in Korean) 143Docto

Comparison of MRCP and ERCP in evaluating the pathology of pancreaticobiliary system

의학과/석사[한글] ERCP(endoscopic retrograde cholangiopancreatography)가 1968년 처음 도입된 이후 췌담도질환의 진단에 있어 널리 이용되고 있으나 시술자의 술기에 의존적이어서 췌담도내로의 삽관실패 및 폐쇄 상부의 조영에 어려움이 있고, 침습적인 검사법으로 합병증을 유발할 수 있다. 최근 비침습적인 방법으로 췌담도의 영상을 얻을 수 있는 MRCP(magnetic resonance cholangiopancreatography)가 도입되어 임상적인 이용이 늘고있다. MRCP는 자기공명영상의 새로운 적용분야로서 췌담도 주변구조의 단면뿐 아니라 췌담도의 투사영상을 얻을 수 있어 조영제의 투여없이 직접 담도 조영술과 유사한 영상을 얻을 수 있다. 또한 시술중 합병증이 거의 없고 시술자에 의존적이지 않으며 폐쇄 양측의 관구조를 조영할수 있고 여러 단면영상을 동시에 얻을 수 있는 장점이 있다. 자기공명영상 기술의 발달로 해상도가 향상되고 있어 담관결석이나 췌담도 폐쇄질환에서의 정확도가 높게 보고되고 있으나 향후 전통적인 췌담도계의 영상방법을 대신할 수 있을지 아니면 보조적인 진단방법일지는 아직 밝혀지지 않았다. 이에 본 연구자는 췌담도질환의 진단에 있어서 MRCP와 ERCP의 영상적 차이 및 MRCP의 진단적 정확도와 임상적 유용성을 평가하기위해 연세의료원에서 간외담관암, 췌장종양, 간외담관결석을 진단받은 환자중 MRCP와 ERCP를 모두 시행받은 57명의 환자를 대상으로 후향적 조사를 시행하였다. 간외담관암은 1995년 7월부터 1997년 6뭘까지 2년간 17예, 췌장종양과 간외담관결석은 1997년 3뭘부터 12월까지 10개월간 각각 16예, 24예로 하였다. 간외담관암은 담관폐쇄의 원인분석, 병변부의 위치 및 경계, 폐쇄상부 및 하부담관의 조영유무 등을 중심으로 비교하였고, 췌장종양에서는 MRP와 ERP의 영상에서 췌관의 두부, 체부, 미부에서 각 구조의 명확도를 5단계(0-4점)로 나누어 췌관조영의 명확도를 평가하고, 또한 결정적인 진단적 정보를 얻었을때를 4점, 진단에 정보를 주지 못할때를 0점으로 주관적으로 점수를 주어 진단적 신뢰도를 평가하였다. 간외담관결석은 결석유무가 확인된 24예에서 MRCP와 ERCP의 진단의 정확도와 민감도를 알아보았고, MRCP에서 병변이 확인 된 20예에서는 각 단면에 따라 결석확인의 용이성을 3단계(0-2점)으로 나누어 평가하였으며 또한 결석의 자기공명영상의 특성을 파악하여 다음과 같은 결과를 얻었다. 1. 간외 담관암 가. 17명의 대상 환자의 평균연령은 62세(43-75)였고 남녀비는 1.8:1이었다. 최종진단은 12예에서는 수술로, 나머지 5예는 임상적 소견, 방사선학적 소견, 세포진 검사 등으로 확진하였는데 Klatskin종양 2예, 총간관암 6예, 근위총수담관암 4예, 중간 총수담관암 2예, 원위 총수담관암 3예였다. 나. 간외담관암의 진단에 있어서 ERCP와 MRCP의 민감도는 병변의 위치분석에서 100%와 94%, 양성과 악성의 구분등 담관폐쇄의 원인분석에서는 100%와 88%, 병변의 상부경계의 확인은 47%와 82%, 병변의 하부경계의 확인은 100%와 82%, 폐쇄 상부담관의 조영은 47%와 100%였고, 폐쇄 하부담관의 조영은 원위 총수담관암 3예를 제외한 14예에서 비교하였는데 각각 100%와 93%에서 확인할 수 있었다. 다. 병변의 상부경계의 확인 및 폐쇄 상부담관의 조영에서는 통계학적으로 유의있게 MRCP에서 우수하였다. 라. MRCP진단의 오류가 2예에서 있었는데 담낭과 근위 총수담관의 영상이 겹쳐 병변관찰이 어려웠던 경우와 원위 총수담관의 대칭적인 협착을 보여 양성병변과 감별이 어려운 경우가 각각 1예씩 있었다. 2. 췌장종양 가. 대상 환자는 16명이었고 평균연령은 61세(42-80)였으며 남녀비는 1.7:1이었다. 최종진단은 9예에서 수술이나 조직학적 검사로, 8예에서는 임상적 추적관찰 및 방사선 소견 그리고 종양표지자의 상승등으로 하였다. 진단은 췌장암 8예(두부 6예, 체부 1예, 미부 1예), 점액분비성 유두상 병변 6예, 장액성 낭선종 2예였다. 나. 췌관조영의 명확도 평가에 있어서 ERP와 MRP의 평균점수는 두부에서 각각 3.44대 2.88, 체부는 2.19대 3.06, 미부는 1.38대 3.06으로 폐쇄 근위부췌관의 조영이 MRP에서 유의있게 높았다. 다. 병변에 의해 췌관의 완전폐쇄가 있었던 8예(50%)에서는 MRP는 폐쇄 양측췌관을 모두 확인할 수 있었는데 반해 ERP는 폐쇄 원위부췌관만을 조영하였다. 라. 진단적 신뢰도 평가에 있어 ERP는 2.81, MRP는 3.94로 MRP에서 유의있게 높았다. 마. 2예의 장액성 낭선종에서는 ERP는 진단적 정보를 제공하지 못한데 반해 MRP는 병변을 정확히 진단하였다. 3. 간외담관결석 가. 24명의 환자를 대상으로 하였고 평균연령은 59세(40-74)였으며 남녀비는 1.2:1이었다. 간외담관결석 유무는 내시경적 제거술을 통해 결석을 직접 확인하거나 수술로서 확인하였는데 이중 2예를 제외한 22예에서 결석이 있었고 이러한 소견을 최적기준으로 하였다. 나. 간외담관결석의 진단에서 민감도 및 진단의 정확도는 ERCP는 86%(22예중 19예), 88%(24예중 21예)였고, MRCP에서는 각각 86%(22예중 19예), 79%(24예중 19예)로 통계학적인 차이가 없었다. 다. MRCP에서의 간외담관결석의 영상특성은 20예에서 분석하였는데 결석확인 용이도의 평균점수는 횡단면 1.6, 관상면 1.55 그리고 투사영상 1.8로 투사영상이 횡단면이나 관상면보다 결석의 확인이 용이하였으나 통계학적 차이는 없었다. 라. T2 강조영상에서 결석은 60%(20예중 12예)에서 신호소실, 40%(20예중 8예)에서 저신호강도로 관찰되었고, 결석에 고신호강도의 내부구성물을 보였던 경우는 57%(20예중 10예)였다. 마. T1 강조영상으로도 촬영한 예는 9예였고 이중 결석을 확인할 수 있었던 6예중 4예는 고신호강도, 2예에서는 저신호강도로 관찰되었다. 이상의 결과로 간외담관암이나 췌장종양에서 MRCP는 ERCP와 유사하거나 우수한 진단적 정확도를 보였고, 폐쇄 원위부 및 근위부 췌담도를 모두 조영할 뿐아니라 종양의 정확한 위치 및 침범정도를 평가할 수 있었다. 또한 간외담관결석의 진단에서 MRCP는 ERCP와 견줄만한 진단적 가치가 있어 진단이 불확실할 때 ERCP전에 MRCP를 우선 시행해 볼 수 있겠다. 따라서 췌담도질환이 의심되는 환자에서 ERCP전에 MRCP를 시행항으로써 침습적인 검사를 줄이고 향후 치료계획을 세우는데 도움이 될 수 있을 것으로 기대된다. 그러나 MRCP의 비용효과 측면이 고려되어야 하며 향후 적응질환에 대한 연구가 더 필요할 것으로 생각된다. [영문] Although ERCP has been the gold standard, having the highest sensitivity and specificity for evaluating diseases of the pancreaticobiliary system, the procedure is associated with complications such as cholangitis and pancreatitis. In contrast, MRCP is a noninvasive imaging modality capable of producing high-quality images of the pancreaticobiliary system. To determine the efficacy of MRCP in diagnosing diseases of the pancreatic and biliary duct, we correlated the image of MRCP with ERCP findings, and then evaluated the diagnostic accuracy of MRCP and compared the difference between the images of MRCP and ERCP. Fifty-seven patients (extrahepatic bile duct cancer, n=17; pancreatic tumors, n=16; extrahepatic bile duct stones, n=24) underwent ERCP and MRCP simultaneously, The MR cholangiograms were acquired with a fast spin-echo (n = 10) or a single shot fast spin-echo (n =47). The Results were as follows: 1. Extrahepatic bile duct (1) Seventeen patients(11 males and 6 females) were analyzed retrospectively during a period of 2 years(July 1995 to June 1997). The mean age was 62 years. The MR cholangiopancreatograms were performed with a fast spin-echo(n = 10) or single shot fast spin-echo(n= 7). (2) Malignant obstruction was confirmed in 12 patients by surgical findings and in 5 patients by clinical follow-up and imaging findings. The final diagnoses were as follows: Klatskin tumor(n = 2), CHD cancer(n = 6), proximal CBD cancer(n = 4), mid CBD cancer(n = 2), distal CBD cancer(n = 3). (3) ERCP and MRCP showed sensitivities of 100% and 94% for location of bile duct obstruction, 100% and 88% for causes of obstruction, 47% and 82% for recognition of the upper margin of lesion, 100% and 82% for recognition of the lower margin of lesion, 47% and 100% for visualization of the bile duct proximal to obstruction, and 100% and 93% for visualization of the bile duct distal to obstruction, respecitively. (4) MRCP was superior to ERCP in recognition of the upper margin of lesion and visualization of the bile duct proximal to obstruction(p < 0.05). 2. Pancreatic tumors (1) Sixteen patients(10 male and 6 female, mean age 61 years) underwent MRP and ERP between March 1997 and December 1997. MRP was performed with single shot fast spin-echo sequence on a 1.5T system. (2) The final diagnosis established by surgical findings(n = 9) or imaging findings and clinical follow-up(n = 7) were as follows: pancreatic cancer(n = 8), mucinous ductal ectasia(n = 6), serous cystadenoma(n =2). (3) MRP and ERP were compared for visualization of the head, body, and tail portion of the pancreatic duct separately and scored as excellent(4), good(3), fair(2), poor(1), and no visualization(0). The overall diagnostic confidence of both modalities also was graded subjectively from non-diagnostic image(0) to definite information(4). (4) Mean score of visualization of the pancreatic duct by MRP and ERP were 2.88 and 3.44 in the pancreatic head(p = NS), 3.06 and 2.19 in the pancreatic body(p = NS), and 3.06 and 1.38 in the pancreatic tail(p < 0.01). Mean score of the diagnostic confidence was 3.94 in MRP and 2.81 in ERP, which had a statistically significant difference(P < 0.05). (5) In 8 patients with obstruction of pancreatic duct due to malignant lesions, MRP demonstrated both the proximal and distal site of obstruction in the pancreatic duct while ERP only visualized the distal site of obstruction. In two cases of serous cystadenoma with lack of communication between the pancreatic duct and cystic neoplasm, MRP characterized the lesion precisely whereas ERP showed no information. (6) MRP was superior in defining the extent of tumor because of the visualization of the surrounding pancreatic parenchyma and the relationship of the ducts, 3. Extrahepatic bile duct stone (1) Twenty-four patients(13 male and 11 female, mean age 59 years) with suspected choledocholithiasis underwent MRCP and ERCP between March 1997 and December 1997. MRCP was performed with single shot fast spin-echo sequence. (2) Twenty-two patients with choledocholithiais and two patients without choledocholithiais were confirmed by surgical findings(n = 8) or stone extraction by sphincterotomy(n = 16). (3) Diagnostic accuracy of MRCP and ERCP in the diagnosis of choledocholithiasis(n = 24) were 79% and 88%, sensitivity were 86% and 86% respectively. (4) Reliance in detection of calculi on each image were evaluated by scoring as definite(2), suspicious(1), no visualization(0) in twenty patients with choledocholithisis on MRCP. Although there was no statistical significance, the calculi was better shown on the projecional in ages(1.8) than axial(1.6) and coronal images(1.55). (5) The typical meniscus sign created by the high signal intensity of bile that was partially surrounding the hypointense stone was better visualized on projectional and axial images(90% respectively) than coronal views(70%). (6) Choledocholithiasis were dipicted as foci of intraluminal signal void in 12(60%) of the 20 patients and foci of intraluminal low intenity signal in 8(40%) of the 20 patients on heavily T2-weighted images. (7) In 10(50%) of the 20 patients, the calculi had internal hyperintense constituents. In conclusion, MRCP has a diagnostic accuracy, similar or superior to ERCP and also demostrate the pancreaticobiliary ducts proximal and distal to the site of obstruction in extrahepatic bile duct cancer and pancreatic tumors. In addition, MRCP can evaluate the exact location of obstuction and extent of tumors. Thus MRCP can be used as a primary diagnostic tool before ERCP when therapeutic intervention for drainage of bile duct is not needed and also provide a means of planning appropriate therapeutic measures. In the diagnosis of choledocholithiais, MRCP has a high sensitivity and diagnostic accuracy, and can characterize stone structure and composition. Thus MRCP may beneficial in patients with high risk of complications from ERCP or a low to moderate clinical suspicion for common bile duct stones, and may play a role in the selection of patients for endoscopic sphincterotomy. Although MRCP may substitute for diagnostic ERCP, further prospective studies is needed to better assess the cost-effectiveness of the technique and define the optimal role of MRCP.restrictio

Scar quality and hand function after Moist Exposed Burn Ointment and skin graft treatment in full

의학과/석사[한글] 화상 재활치료에서 화상 환자의 피부 병변은 심각한 장애요소로 작용한다. 특히 중증 화상의 경우 관절부위 움직임의 제한, 소양감, 말초 신경 병변 등을 유발할 수 있어 이러한 피부 병변에 대한 관리가 필요한 실정이다. 중증 화상시 수술적 치료를 행하지 못하는 경우 MEBO 치료가 화상 습성 치료법으로 창상의 환경을 생리 습윤하게 유지시키고 한선 분비 상피세포, 피하조직세포에 성장과 분화를 촉진시키는 새로운 피부 조직이 형성되도록 하는 치료법으로 사용되고 있다. 본 연구에서는 중증 수부 화상 환자에서 기존의 피부 이식술치료와 MEBO 치료를 비교했을 때 화상 피부 흉터 상태와 손기능의 상태에 차이가 있는지를 알아보고자 하였다.화상 센터에 내원한 수부의 중증 화상 환자를 대상으로 기존의 피부 이식 치료를 받은 환자군과 MEBO 치료를 받은 환자군으로 나누어 화상후 비후성 반흔의 정도를 평가하였다. 먼저 밴쿠버 화상 흉터 척도(Vancouver scar scale)를 평가 하였고, 화상 피부상태의 객관적인 지표로 피부탄력도, 색소침착정도, 수분증발량, 미세혈류량, 화상 흉터의 두께를 측정하였다. 손의 기능평가를 위해 능동적 손가락 관절 운동 범위와 젭슨 손기능 평가(Jebsen hand function test) 및 미시간 손기능 평가(Michigan Hand Function Questionnaire)를 실시하여 다음과 같은 결과를 얻게 되었다.1. 밴쿠버 흉터 측정 검사상 탄력지수는 피부이식 치료군에 비해 MEBO 치료군에서 낮은 지수를 보였고, 화상 흉터의 두께지수는 MEBO 치료군에서 화상 후 6개월 시점의 지수가 1개월 때에 비해 증가된 수치를 나타냈다..2. 객관적인 화상 피부 상태는 기존의 피부이식 치료군의 경우보다 MEBO 치료군에서 피부 탄력도의 증가, 색소 침착의 감소, 경표피 수분 증발량의 증가를 보였다.3. 흉터의 두께는 수상 초기 1개월 경과시 피부 이식 치료군에 비해 MEBO 치료군이 감소된 상태였지만, 6개월 경과시 피부이식 치료군보다 증가되었다.4. 젭슨 손기능 평가 및 미시간 손기능 평가에서 두 군간의 의미있는 차이를 보이지 않았다.결론적으로 중증 수부 화상의 치료 방법으로 수술적 치료외에 MEBO 치료를 하나의 대안으로 고려할 수 있을 것으로 사료되며 향후 6개월 이상의 만성적인 피부 상태에 대한 고찰이 필요할 것이다. [영문]There is a evidence of improved healing of full thickness wounds in wet and moist environment. The objectives of this study were to determine the pattern of scar formation and hand function after full thickness hand burn and to compare the effect between MEBO treatment and skin graft. Scars of full thickness burn wound from hand dorsum were estimated in a prospective comparative study between two types of treatment, MEBO and skin graft wound. Scar on hand dorsum was assessed both clinically(Vancouver scar scale) and basically with serial objective measurement of pigmentation, erythema, pliability, transepideramal water loss, thickness and perfusion. Hand function was evaluated by Jebsen hand function test and Michigan Hand Function Questionnaire. Vancouver Scar scales were significantly better in the MEBO group than skin graft group. Scar thickness, transepidermal loss were increased whereas pigmentation value was decreased in MEBO treatment group. There was no significant difference in hand function between two groups. MEBO application could be an alternative treatment to conventional treatment in full thickness hand burn wound. Nevertheless, more studies are yet to come for evaluating how MEBO treatment affect skin condition of burn inury.ope