양극산화알루미늄 기반 연줄기용 실시간 수분포텐셜 측정 시스템 개발

학위논문(박사) -- 서울대학교대학원 : 공과대학 기계항공공학부(멀티스케일 기계설계전공), 2023. 8. 이정훈.Monitoring water potential in agriculture is essential for efficient irrigation management and conservation efforts. In this study, we propose a novel approach for continuous and convenient water potential measurement, specifically designed for analyzing water stress in plant soft stems. Our system incorporates a wireless communication method, making it easily applicable in the agricultural field. By providing real-time water potential data, our system empowers farmers with valuable feedback to optimize irrigation plans, reduce water waste, and promote sustainable farming practices. Our water potential sensor in the system operates on the capacitive sensing principle, analyzing relative humidity within an anodic aluminum oxide (AAO) layer. An analog-to-digital converter, coupled with a wireless communication module, effectively records capacitance data from the sensing system. By utilizing calibration data derived from mixtures of superabsorbent polymer (SP) and deionized water (DIW), our sensor can accurately represent corresponding water potential values. Notably, our method exhibits exceptional coherence between capacitance and water potential values, especially above -7 MPa, aligning perfectly with results obtained from tomato stems. Over the course of several days, we conducted measurements by connecting sap flow and water potential sensors in series on a tomato stem. When there was sufficient sunlight, we observed an increase in sap flow and a decrease in water potential. Conversely, during nighttime, sap flow decreased, and water potential showed an increase. During periods of restricted irrigation, both sap flow and water potential signals experienced a decline, leading to the activation of emergency watering signals. These observations demonstrate the dynamic relationship between sap flow and water potential, as well as the importance of real-time monitoring to make informed decisions about irrigation management and water conservation practices. Our continuous water potential monitoring system plays a crucial role in quantitatively monitoring plant stem water stress, providing valuable insights for farmers to make informed decisions about adjusting irrigation schedules. By leveraging this innovative approach, farmers can optimize water usage and enhance the overall quality of agricultural products. Moreover, the system holds great promise in promoting more sustainable agriculture practices by conserving water resources and reducing water wastage. With its potential to revolutionize irrigation practices, this technology represents a significant step towards more efficient and environmentally-friendly agricultural operations.농업 분야에서 수분 포텐셜 모니터링은 급수 일정 관리 및 급액량을 결정하는데 도움을 주는 중요한 데이터이다. 본 연구에서는 더 나은 관개 계획 피드백을 위해 연질 식물 줄기에 삽입이 가능한 형태의 지속적인 수분 포텐셜 측정 시스템의 개발 과정을 설명한다. 본 연구에서는 MEMS 공정 기술과 PCB 가공 기술을 이용해 양극 산화 알루미늄(AAO) 층 내부의 습도를 측정하는 정전용량 측정 방식의 수분 포텐셜 센서를 제작하였다. 무선 통신 모듈 시스템이 내장되어 있는 아날로그-디지털 변환기는 무선 통신을 이용하여 수분 포텐셜 센서의 정전용량 데이터를 측정하고 서버에 이 내용을 기록할 수 있다. 이러한 플랫폼은 향후 본 시스템이 전기설비 접근성 및 통신에 제약이 있는 농가에서 활용이 용이할 것으로 기대된다. 센서의 칼리브레이션을 위해 고흡수성수지(SP)와 증류수(DIW) 각종 비율로 혼합하였고 각 혼합비가 가지는 수분 포텐셜 값을 도출하여 각 표준 환경에서 수분 포텐셜 센서를 칼리브레이션 진행하였고 모든 센서들이 유사한 신호 분포도를 보여주었다. 특히 센서가 잘 동작하는 구간은 -7 MPa 이상의 구간으로서 토마토 줄기에서 측정을 시도 하였을 때 해당 구간 안에서 시그널이 나오는 것을 확인 하였다. 수 일 동안 토마토 줄기에 수분 포텐셜 센서와 수액 흐름 센서와 함께 직렬로 연결하여 데이터 측정을 진행하였다. 햇빛이 충분할 때, 수액의 흐름은 증가하지만, 반면에 줄기 내 수분 포텐셜은 감소하는 양상을 보였다. 반대로 밤에는 수액 흐름이 없으면서 내부 수분 포텐셜이 증가하는 양상을 보여주었다. 급수가 제한된 조건에서는 수액 흐름과 수분 잠재 신호가 모두 감소할 때 식물체가 수분스트레스를 받은 것을 확인하였고, 비상급수를 통해 식물이 정상상태로 돌아오는 양상을 확인하였다. 이러한 지속적인 수분 포텐셜 모니터링 시스템은 식물 줄기의 수분 스트레스를 정량적으로 모니터링하고 급수 일정을 설정하여 농업 분야에서 고품질의 과실을 수확 할 수 있는데 도움을 줄 수 있을 것으로 기대된다.ABSTRACT I TABLE OF CONTENTS III LIST OF FIGURES V CHAPTER 1. GENERAL INTRODUCTION １ 1.1. SMART FARM AND TECHNOLOGIES １ 1.1.1. Current smart farm technology １ 1.1.2. MEMS sensors for smart farm ４ 1.2. WATER POTENTIAL ７ 1.2.1. Importance of measuring water potential for plant growth and irrigation management ７ 1.2.2. Understanding the key components of water potential in plants ９ 1.2.3. Conventional water potential measurements for soil 11 1.2.4. Requirement for plant in-situ water potential measurement 16 1.2.5. Water potential measurement methods for plants 17 1.3. RESEARCH OBJECTIVE 22 BIBLIOGRAPHY 24 CHAPTER 2. METHODS: SENSOR DESIGN, FABRICATION AND MEASUREMENT SET UP 28 2.1. DESIGN OF MICRONEEDLE SAP FLOW SENSOR PROBE 28 2.1.1. Structure design of the water potential sensor 28 2.1.2. Fabrication process of water potential sensor chip 29 2.1.3. AAO anodization process 31 2.1.4. Sensor chip design and PCB packaging 32 2.1.5. Fabrication result 34 2.2. MEASUREMENT SETUP 38 2.2.1. Capacitance measurement module 38 2.2.2. Field test set up 39 BIBLIOGRAPHY 40 CHAPTER 3. THEORY AND ANALYSIS 41 3.1. AAO CHARACTERISTICS AND HUMIDITY CAPACITIVE RESPONSE 41 3.1.1. Anodic aluminum oxide(AAO) 41 3.1.2. AAO humidity sensing characteristics 43 3.2. WATER MOLECULE ADSORPTION CHARACTERISTICS OF THE AAO 47 3.2.1. Chemisorption and physisorption of water on the AAO 47 3.2.2. Capacitive signal of the AAO by on sorption ratio 50 3.2.3. Capillary condensation and isothermal characteristics of the AAO 52 3.3. STEM WATER POTENTIAL 56 3.3.1. The relationship between water potential and relative humidity 56 3.3.2. Plant stem humidity condition 59 BIBLIOGRAPHY 63 CHAPTER 4. SENSOR CALIBRATION AND THERMAL CHARACTERISTIC EVALUATION 67 4.1. SUPERABSORBENT POLYMER ANALYSIS 67 4.1.1. Superabsorbent polymer water activity measurement as a reference material 67 4.2. WATER POTENTIAL SENSOR ANALYSIS 72 4.2.1. Water potential sensor calibration in the reference SP condition 72 4.2.2. Sensor response test and characteristics 76 4.2.3. Temperature effect 79 BIBLIOGRAPHY 82 CHAPTER 5. IN-VIVO MEASUREMENT OF SOFT STEM PLANT WATER POTENTIAL SENSOR83 5.1. FIELD MEASUREMENT OF THE WATER POTENTIAL SENSOR 83 5.1.1. Field test installation set up 83 5.1.2. Water potential signal from a drying tomato stems 84 5.1.3. Scholander prerssure chamber comparison result 87 5.1.4. Irrigation regulation and signal response 89 BIBLIOGRAPHY 91 CHAPTER 6. CONCLUSIONS 92박

Impact of Cytomegalovirus Disease on New-Onset Type 2 Diabetes Mellitus: Population-Based Matched Case-Control Cohort Study

BACKGROUND: A latent cytomegalovirus (CMV) cause chronic inflammation through undesirable inflation of cell-mediated immune response. CMV immunoglobulin G has been associated with cardiovascular disease and type 1 diabetes mellitus. We evaluated impact of CMV diseases on new-onset type 2 diabetes mellitus (T2DM). METHODS: From the Korean Health Insurance Review and Assessment Service claim database of entire population with 50 million, we retrieved 576 adult case group with CMV diseases diagnosed with International Statistical Classification of Diseases and Related-Health Problems 10th Revision (ICD-10) B25 code between 2010 and 2014 after exclusion of patients with T2DM to 2006. The 2,880 control patients without T2DM from 2006 to cohort entry point were selected between 2010 and 2014 by age, sex matching with case group. The subjects without new-onset T2DM were followed until 2015. T2DM, hypertension (HTN), dyslipidemia (DYS), and end-stage renal disease (ESRD) were coded as ICD-10. RESULTS: The frequency of new-onset T2DM in case group was significantly higher than that in control (5.6% vs. 2.2%, P<0.001). The group with T2DM (n=95) had higher incidence of CMV diseases than the group without T2DM (n=3,361) (33.7% vs. 16.2%, P<0.001). In multivariate regression model adjusted by age, sex, lower income, HTN, and DYS, the incidence rate (IR) of T2DM in case group was significantly higher than that in the control group (IR per 1,000, 19.0 vs. 7.3; odds ratio, 2.1; 95% confidence interval, 1.3 to 3.2). The co-existence of HTN, DYS, and ESRD with CMV diseases did not influence the IR of T2DM. CONCLUSION: CMV diseases increase the patients' risk of developing T2DM.ope

건설산업 발전을 위한 건설보증 역할강화 방안(Strategies to strengthen the role of the construction surety to develop the construction economy)

노트 : 이 연구보고서의 내용은 국토연구원의 자체 연구물로서 정부의 정책이나 견해와는 상관없습니다

Two Cases of Chickenpox Developed from an Immunocompromised Patient with Localized Herpes Zoster

Varicella zoster virus causes chickenpox, which is highly contagious, at primary infection and herpes zoster at reactivation. The varicella zoster virus may be more contagious and cause serious outbreaks in immunocompromised patients. There are some reports of outbreaks of chickenpox in patients with herpes zoster. Here, we describe a case of localized herpes zoster occurring in an immunocompromised patient during hospitalization in a specialized ward for immunocompromised patients. This episode resulted in two newly developed, hospital-acquired cases of chickenpox. If we had isolated the index patient who had localized herpes zoster immediately, the two cases of chickenpox could have been prevented. Therefore, patients with localized herpes zoster should be isolated in wards with immunocompromised patients.ope

금속 나노 슬릿의 구조적 요인이 테라헤르츠 전기장 집속에 미치는 효과

학위논문 (박사)-- 서울대학교 대학원 : 전기·컴퓨터공학부, 2016. 2. 박남규.Electric field enhancement inside metal-insulator-metal gaps, especially slit structure, is investigated in Terahertz range. Dependencies of field enhancement on slit width and thickness are calculated by modal expansion method for perfect electric conductor approximation and numerical finite difference time domain method for real metal. Field enhancement increases as slit width and thickness decrease. Slit thickness as well as width has a large influence on field enhancement when the width becomes small. To explain the tendencies we propose a model based on charge and capacitor concept. In practice, fabricated metal slit which has a few nanometer sized width usually shows asymmetric and tapered shape due to complexity of fabrication processes. Dependence of field enhancement on tapered angle in symmetric and asymmetric slit is also investigated. Numerical results show that thickness of smallest gap region is the most important for enhancement factor if tapered angle is less than 70 degree. This confined field can be utilized to enhance light-matter interaction. By placing metal nano gap structure on vanadium dioxide film which has transition property between Mott insulator and metal phase at the specific temperature, we can observe enhanced interaction between vanadium dioxide film and terahertz field.1. Introduction 1 2. Calculation Methods 3 2. 1. Finite Difference Time Domain (FDTD) 3 2. 2. Build-up System for FDTD 6 2. 3. Modal Expansion Method 8 2. 4. Modal Expansion for metal slit on film 8 3. Field Enhancement Dependence on Width and Thickness of Metal Nano Slit at Terahertz (THz) Regime 25 3. 1. Introduction 26 3. 2. Effects of Width and Thickness of Nano Slit on Field Enhancement 27 3. 3. Modeling using Capacitor Concept 31 4. THz Field Enhancement in Asymmetric and Tapered Nano Slit 37 4. 1. Introduction 38 4. 2. Effects of Asymmetric and Tapered Shape of Nano Slit on Field Enhancement 40 5. Metal Nano Gap Structures on Vanadium dioxide (VO2) film 47 5. 1. Introduction 48 5. 2. Sample Fabrications 50 5. 2. 1. Preparation of VO2 film 50 5. 2. 2. Fabrications of slot arrays on VO2 film 53 5. 3. Properties of VO2 film 58 5. 4. Transmission properties of Nano Gap Structure on VO2 film 62 6. Conclusion 67 Bibliography 69 국문초록 74 List of publications 75 Conferences 77Docto

Impact of first-line antifungal agents on the outcomes and costs of candidemia

Candida species are the leading causes of invasive fungal infection among hospitalized patients and are responsible for major economic burdens. The goals of this study were to estimate the costs directly associated with the treatment of candidemia and factors associated with increased costs, as well as the impact of first-line antifungal agents on the outcomes and costs. A retrospective study was conducted in a sample of 199 patients from four university-affiliated tertiary care hospitals in Korea over 1 year. Only costs attributable to the treatment of candidemia were estimated by reviewing resource utilization during treatment. Risk factors for increased costs, treatment outcome, and hospital length of stay (LOS) were analyzed. Approximately 65% of the patients were treated with fluconazole, and 28% were treated with conventional amphotericin B. The overall treatment success rate was 52.8%, and the 30-day mortality rate was 47.9%. Hematologic malignancy, need for mechanical ventilation, and treatment failure of first-line antifungal agents were independent risk factors for mortality. The mean total cost for the treatment of candidemia was $4,743 per patient. Intensive care unit stay at candidemia onset and antifungal switch to second-line agents were independent risk factors for increased costs. The LOS was also significantly longer in patients who switched antifungal agents to second-line drugs. Antifungal switch to second-line agents for any reasons was the only modifiable risk factor of increased costs and LOS. Choosing an appropriate first-line antifungal agent is crucial for better outcomes and reduced hospital costs of candidemia.ope

The Incidence and Effect of Cytomegalovirus Disease on Mortality in Transplant Recipients and General Population: Real-world Nationwide Cohort Data

Background: In addition to the conventional opportunistic infections in solid organ transplantation (SOT) and hematopoietic stem cell transplantation (HSCT) recipients, cytomegalovirus (CMV) infection is associated with various chronic inflammatory diseases or poor outcomes in non-immunocompromised critically ill patients. To evaluate the burden or outcome of CMV replication in non-transplant individuals, we compared the incidence rates (IRs) for CMV disease and all-cause mortality between SOT recipients, HSCT recipients, and non-transplant population. Methods: The SOT (N=16,368) and HSCT (N=10,206) cohorts between 2010 and 2015 were established using the WHO ICD-10 from the whole population-based large database of the Health Insurance Review & Assessment Service (HIRA). CMV cases, defined as symptomatic disease with isolation of virus, DNA, pp65 antigen, and pathology except CMV syndrome, were extracted with the unique codes for relief of medical costs of HIRA in the same dataset. Cox's proportional hazard regression analyses and log-rank test in the Kaplan-Meier curves were performed to compare all-cause mortality between the three groups. Results: The CMV IRs adjusted by age and sex were significantly higher in the SOT (adjusted IR [95% confidence intervals], 33.1 [28.8-38.0] per 1,000 person-years) and HSCT recipients (5.1 [4.6-6.1] per 1,000 person-years) than in the whole population (0.58 [0.49-0.67] per 100,000 person-years). However, SOT recipients with CMV (18/283, 6.4%) had significantly lower all-cause mortality than non-transplant individuals with CMV (207/1,258, 16.5%) (adjusted hazard ratio [95% CI], 0.42 [0.25-0.67], log-rank P < 0.001). Conclusion: These data suggest that CMV disease in patients without transplants is associated with poor outcomes.ope

Safety and Efficacy of Ziagen (Abacavir Sulfate) in HIV-Infected Korean Patients

BACKGROUND: Abacavir is a widely-used nucleoside reverse transcriptase inhibitor for the treatment of human immunodeficiency virus (HIV) infection. Mandatory postmarketing surveillance was conducted in Korea to monitor the safety and evaluate the effectiveness of Ziagen® (abacavir sulfate 300 mg; ViiV Healthcare, Middlesex, UK). MATERIALS AND METHODS: An open-label, multi-center, non-interventional postmarketing surveillance study was conducted from June 2010 to June 2016 to monitor the safety and effectiveness of Ziagen across 12 hospitals in Korea. Subjects older than 18 years taking Ziagen according to prescribing information were enrolled. The primary outcome was defined as the occurrence of any adverse events after Ziagen administration. Secondary outcomes included the occurrence of adverse drug reactions, occurrence of serious adverse events, and effectiveness of Ziagen administration. RESULTS: A total of 669 patients were enrolled in this study, with a total observation period of 1047.8 person-years. Of these, 90.7% of patients were male. The mean age of patients was 45.8±11.9 years. One-hundred ninety-six (29.3%) patients reported 315 adverse events, and four patients reported seven serious adverse events, without any fatal events. There was one potential case of an abacavir hypersensitivity reaction. Among the 97 adverse drug reactions that were reported from 75 patients, the most frequent adverse drug reactions included diarrhea (12 events), dyspepsia (10 events), and rash (9 events). No ischemic heart disease was observed. In the effectiveness analysis, 91% of patients achieved HIV-1 RNA under 50 copies/mL after 24 months of observation with abacavir administration. CONCLUSION: Our data showed the safety and effectiveness of Ziagen in a real-world setting. During the study period, Ziagen was well-tolerated, with one incident of a clinically suspected abacavir hypersensitivity reaction. The postmarketing surveillance of Ziagen did not highlight any new safety information. These data may be helpful in understanding abacavir and the HIV treatment practices in Korea.ope

Vaccination For Patients With Rheumatic Diseases In The Era Of Biologics

A large proportion of patients with rheumatic disease have an immunocompromised status resulting from disease pathogenesis itself and/or several immunosuppressive drugs including biologics. These conditions are closely related to a higher risk of a variety of infectious diseases. Therefore, a few vaccinations for vaccine‐preventable pathogens should be considered in patients with rheumatic disease at the appropriate time. The quadrivalent inactivated influenza and pneumococcal vaccinations, including both 13‐valent conjugate and 23‐valent polysaccharide vaccines, are strongly recommended in all patients with rheumatic disease. The immunogenicity of influenza and pneumococcal vaccination have generally been demonstrated in patients with rheumatic disease on biologics except for rituximab and abatacept. Vaccines can be administered during therapy with tumor necrosis factor-α antagonists but may be more ideal during a stable or remission status without immunosuppressive therapy. In particular, vaccination should be done at least 6 months after an injection of rituximab as a B‐lymphocyte‐depleting biologic. Basically, all live-attenuated vaccines should be avoided in highly immunocompromised rheumatic disease patients. The vaccination for herpes zoster (HZ) can be taken carefully according to degree of immunosuppression because the currently available vaccine is only live‐attenuated. The newly developed subunit HZ vaccine is promising in immunocompromised patients with rheumatic disease.ope

The influence of vaccination on the clinical features of hemorrhagic fever with renal syndrome in the last 5 years

Background/Aims: Hemorrhagic fever with renal syndrome (HFRS) caused by Hantaan virus is an endemic febrile disease in Korea. Although inactivated Hantaan virus vaccine has been introduced, the effect of vaccination is not clear. We evaluated the effect of vaccination on the incidence rate and clinical features of HFRS based on our clinical experience. Methods: Group I consisted of the patients with confirmed HFRS from a total of 131 patients who were seropositive for Hantaan virus at one tertiary teaching hospital from January 2002 to December 2006. Group II contained 100 patients treated as HFRS at the same hospital from January 1986 to December 1990, before the introduction of the vaccine. Then, we compared the clinical features of the two groups. We confirmed whether the patients had been vaccinated by reviewing their medical records and from telephone interviews. Results: Only 16 (12.2%) of the 131 patients who were seropositive for Hantaan virus were confirmed to have overt HFRS during the most recent 5 years. The incidence of overt HFRS was significantly lower in vaccinees (5%, 3 of 56) than in non-vaccinees (20%, 10 of 50) (p=0.025). The prevalence of renal failure (62.5 vs. 95%, p<0.001) and oliguria (6.25 vs. 46%, p=0.002) was significantly lower in group I than in group II. Three patients were treated with dialysis and none died in group I, versus 17 and 8, respectively, in group II. Conclusions: It appears that Hantaan virus vaccine has helped to reduce the amount of serious illness and the occurrence of HFRS.ope