Development of a New Single Port Surgery Robot with Increased Torque and Workspace

This paper presents the development of a new single port surgery robot, Plat spring driven mech-anism equipped robot for single port LAparoscopic Surgery (PLAS), with plate spring driven mechanism. Recently, the number of single port laparoscopic surgery (SILS) that can easily conceal postoperative scars is increasing, and robotic SILS platforms are being developed for solving inconvenient maneuverability of manual SILS. However, the drive mechanism of most robotic SILS platforms existing consists of wire, therefore cannot afford to deliver sufficient force, and the wire is mechanically deformed, thus causing negative effects on movement accuracy. Due to this limitation, a precious operation cannot be conducted by using conventional robotic SILS platforms. Accuracy and force are reduced as the workspace is ex-panding. The purpose of proposed robot is to increase tissue handling force of forceps by using plate spring driven mechanism, and to conduct more stable and precious operations in an expanded area. Eval-uations of PLAS were performed and its feasibility as a new effective robotic SILS platform was proved ⓒ 2013 DGISTI. INTRODUCTION 1 -- 1.1 Introduction to Single Incision Laparoscopic Surgery (SILS) 1 -- 1.2 Previous researches of robotic SILS 5 -- 1.3 Advantages and disadvantages of current SILS robots 7 -- 1.4 Plate spring driven mechanism 10 -- 1.5 Research contents and goals 13 -- II. DESIGN 15 -- 2.1 Ideal robotic SILS platform 15 -- 2.2 New robotic SILS platform 17 -- 2.1.1 Force requirement 18 -- 2.1.2 Considerations on work Space and degree of freedom 19 -- 2.3 Mechanical implementation of joints 23 -- III. DIRECT AND INVERSE POSITION ANALYSIS 36 -- 3.1 Direct Kinematics 40 -- 3.2 Inverse Kinematics 41 -- IV. VELOCITY AND JACOBIAN ANALYSIS 45 -- 4.1 Direct and Inverse Velocity Problem 47 -- 4.2 Singularity Analysis 48 -- V. EXPERIMENTAL METHODS AND RESULTS 49 -- 5.1 Measuring forces and results 49 -- 5.2 Assessment for reliability of movements and its results 57 -- VI. CONCLUSION AND FURTHER WORKS 61본 연구에서는 판 스프링을 구동 메커니즘으로 하는 새로운 형태의 단일공복강경 수술 로봇을 개발하였다. 최근, 복부에 3~5개의 상처를 남기는 기존의 복강경 수술의 대안으로 수술 후 상처를 쉽게 숨길 수 있는 배꼽을 통한 단일 공 복강경 수술(single port laparoscopic surgery)의 수요가 증가하는 추세이다. 하지만 단일 공 복강경 수술은 내시경과 두 개의 겸자(forceps)가 단 하나의 침습 구로 삽입되어 시술 중 도구간의 충돌을 피하기 어려우며, 작업 공간을 확보하기도 힘들다. 이러한 문제를 해결하기 위해 여러 가지 단일 공 복강경 수술 로봇이 개발 되고 있지만 수술을 하기에 충분한 힘을 전달하지 못하는 문제가 있다. 이 논문에서는 위와 같은 문제를 해결하고, 수술에 필요한 충분한 힘과 넓은 작업영역을 확보하기 위해 판 스프링으로 구동되는 단일 공 수술로봇을 설계, 제작한 후 성능평가를 실시했다. 국내에서는 처음 개발되는 Y 타입 단일 공 수술로봇을 개발하기 위해 매뉴얼 단일 공 복강경 수술의 임상적인 제한 사항과 기존에 개발된 단일 공 복강경 수술로봇의 장단점을 심도 있게 분석하여 기구 설계에 적용시켰다. 특히 의사들의 현장 경험과 의견을 수용하여 기구설계에 적극 반영하였으며, 기존 단일 공 수술 로봇들보다 넓은 작업공간을 갖는 단일 공 수술 로봇을 개발할 수 있었다. ⓒ 2013 DGISTMasterdCollectio

A comparative study between sterile freeze-dried and sterile pre-hydrated acellular dermal matrix in tissue expander/implant breast reconstruction

Background In implant-based breast reconstruction, acellular dermal matrix (ADM) is essential for supporting the inferolateral pole. Recent studies have compared non-sterilized freeze-dried ADM and sterilized pre-hydrated ADM, but have not assessed whether differences were attributable to factors related to sterile processing or packaging. This study was conducted to compare the clinical outcomes of breast reconstruction using two types of sterile-processed ADMs. Methods Through a retrospective chart review, we analyzed 77 consecutive patients (85 breasts) who underwent tissue expander/implant breast reconstruction with either freeze-dried ADM (35 breasts) or pre-hydrated ADM (50 breasts) from March 2016 to February 2018. Demographic variables, postoperative outcomes, and operative parameters were compared between freeze-dried and pre-hydrated ADM. Biopsy specimens were obtained for histologic analysis. Results We obtained results after adjusting for variables found to be significant in univariate analyses. The total complication rate for freeze-dried and pre-hydrated ADMs was 25.7% and 22.0%, respectively. Skin necrosis was significantly more frequent in the freeze-dried group than in the pre-hydrated group (8.6% vs. 4.0%, P=0.038). All other complications and operative parameters showed no significant differences. In the histologic analysis, collagen density, inflammation, and vascularity were higher in the pre-hydrated ADM group (P=0.042, P=0.006, P=0.005, respectively). Conclusions There are limited data comparing the outcomes of tissue expander/implant breast reconstruction using two types of sterile-processed ADMs. In this study, we found that using pre-hydrated ADM resulted in less skin necrosis and better integration into host tissue. Pre-hydrated ADM may therefore be preferable to freeze-dried ADM in terms of convenience and safety

FUEL PERFORMANCE CODE COSMOS FOR ANALYSIS OF LWR UO2 AND MOX FUEL

The paper briefs a fuel performance code, COSMOS, which can be utilized for an analysis of the thermal behavior and fission gas release of fuel, up to a high burnup. Of particular concern are the models for the fuel thermal conductivity, the fission gas release, and the cladding corrosion and creep in UO2 fuel. In addition, the code was developed so as to consider the inhomogeneity of MOX fuel, which requires restructuring the thermal conductivity and fission gas release models. These improvements enhanced COSMOS's precision for predicting the in-pile behavior of MOX fuel. The COSMOS code also extends its applicability to the instrumented fuel test in a research reactor. The various in-pile test results were analyzed and compared with the code's prediction. The database consists of the UO2 irradiation test up to an ultra-high burnup, power ramp test of MOX fuel, and instrumented MOX fuel test in a research reactor after base irradiation in a commercial reactor. The comparisons demonstrated that the COSMOS code predicted the in-pile behaviors well, such as the fuel temperature, rod internal pressure, fission gas release, and cladding properties of MOX and UO2 fuel. This sufficient accuracy reveals that the COSMOS can be utilized by both fuel vendors for fuel design, and license organizations for an understanding of fuel in-pile behaviors.close

Clinicopathologic Factors Affecting Recurrence after Curative Surgery for Stage I Colorectal Cancer

Purpose: The objective of the current study was to identify the clinicopathological risk factors affecting recurrence after a curative resection for stage I colorectal cancer. Methods: We retrospectively studied 434 patients who underwent a curative resection for stage I colorectal cancer between January 1999 and December 2004. Postoperative oral chemotherapy was performed in 189 patients (45.3%). The following prognostic factors were correlated with recurrence: age, gender, preoperative carcinoembryonic antigen level, location of tumor, T stage, size of tumor, histologic differentiation, growth pattern, and lymphovascular invasion. The median follow-up duration was 65 months. Results: The overall recurrence rate was 4.6% (20/434). The median time to recurrence was 33 months. Two-thirds of the recurrence occurred more than two years after surgery. Risk factors associated with recurrence were rectal cancer (P = 0.009), T2 stage (P = 0.010), and infiltrative growth pattern (P = 0.020). A Cox proportional hazards regression analysis demonstrated that the infiltrative growth pattern was an independent predictor for recurrence. Tumor cell budding was observed in all pathologic reviews with recurrence. Conclusion: Long-term follow-up is necessary for stage I colorectal patients with high risk factors like rectal cancer, T2 stage, and infiltrative growth pattern. © 2012 The Korean Society of Coloproctology

A Case of Propofol-Induced Oropharyngeal Angioedema and Bronchospasm

Propofol (2,6-diisopropylphenol) is an ultrashort-acting sedative agent with sedative and amnestic effects that is used not only for anesthesia but also for sedation during minor outpatient procedures and endoscopic examinations. Rare cases of anaphylaxis following propofol administration have been reported in the medical literature. Documentation of anaphylaxis is often lacking because the cause and effect relationship is often hard to prove. Only a minority of patients get referred for allergy testing to confirm the offending drug. Here we report a 74-year-old woman who had an anaphylactic reaction with severe oropharyngeal edema and bronchospasm for a few minutes after receiving propofol during endoscopic examination. An allergy skin test was positive for both propofol and soybean. Soybean in the intralipid is one component of propofol, and we concluded that this anaphylaxis was caused by soybean

Surgical Outcomes after Total Colectomy with Ileorectal Anastomosis in Patients with Medically Intractable Slow Transit Constipation

Purpose: The aim of this study was to evaluate outcomes of a total colectomy with ileorectal anastomosis in patients with slow transit constipation. Methods: A retrospective review of 37 consecutive patients with slow transit constipation who underwent a total colectomy between 1994 and 2008 was undertaken. Preoperative and postoperative Wexner’s constipation scores were collected and used to evaluate the outcomes after surgical treatment. Also patients ’ postoperative satisfaction scores were collected using a 4-point scale. Results: The 37 patients consisted of 31 women and 6 men, with a median age of 41 years (range, 17 to 71 years). Pre- and post-operative Wexner’s scores were collected from 33 patients (89.1%), and the mean preoperative Wexner’s score was 19.3 (range, 11 to 24), which decreased to an average post-operative score of 2.3 (range, 0 to 8). Neither intraoperative complications nor postoperative mortalities were noted. Five patients (13.5%) had early postoperative complications, and the most common complication was postoperative ileus (10.8%). Seven patients (18.9%) had late postoperative complications, and postoperative ileus (10.8%) was also the most common. Twenty seven of 33 patients were satisfied with their surgical outcome (81.8%). Conclusion: A total colectomy with ileorectal anastomosis might be an effective surgical procedure with acceptable morbidity to treat medically intractable slow transit constipation

Clinical Significance of a Large Difference (≥ 2 points) between Biopsy and Post-prostatectomy Pathological Gleason Scores in Patients with Prostate Cancer

We investigated the clinical significance of large difference (≥ 2 points) between biopsy-derived (bGS) and post-prostatectomy Gleason scores (pGS). At 14 medical centers in Korea, 1,582 men who underwent radical prostatectomy for prostate cancer were included. According to the difference between bGS and pGS, the patients were divided into three groups: A (decreased in pGS ≥ 2, n = 30), B (changed in pGS ≤ 1, n = 1,361; control group), and C (increased in pGS ≥ 2, n = 55). We evaluated various clinicopathological factors of prostate cancer and hazards for biochemical failure. Group A showed significantly higher mean maximal percentage of cancer in the positive cores (max%) and pathological T stage than control. In group C, the number of biopsy core was significantly smaller, however, tumor volume and max% were significantly higher and more positive biopsy cores were presented than control. Worse pathological stage and more margin-positive were observed in group A and C than in control. Hazard ratio for biochemical failure was also higher in group A and C (P = 0.001). However, the groups were not independent factors in multivariate analysis. In conclusion, large difference between bGS and pGS shows poor prognosis even in the decreased group. However it is not an independent prognostic factor for biochemical failure

In situ induction of dendritic cell–based T cell tolerance in humanized mice and nonhuman primates

Administration of an ICAM-1–specific antibody arrests dendritic cells in a semi-immature state and facilitates antigen-specific T cell tolerance to islet allografts in humanized mice and Rhesus monkeys

Modeling and parametric studies of the effect of inhomogeneity on fission gas release in LWR MOX fuel

To analyze the effect of an inhomogeneous mixture of an PuO2 powder on fission gas release in MOX fuel, a model has been developed using the assumption that gas release mechanism in Pu-rich particles is identical with that in UO2 fuel. A parametric study was performed to see the respective effect of the number density, size and fraction of Pu retained in the Pu-rich particles on gas release in MOX fuel. The model shows that, for the condition of all the other remaining parameters being fixed, more gas is released in a MOX fuel for lower number density of, smaller size of, and larger fraction of Pu retained in, the Pu-rich particles. However, there exists some condition or combination of parameters for which the effect of inhomogeneity on gas release is negligible depending on the characteristics of MOX fuel. Comparison with measured data for OCOM MOX fuel shows that the present model can predict the level of gas release in MOX fuel once the release mechanism in the Pu-rich particles is known.close4

Modeling of creep behavior of Zircaloy-4 by considering metallurgical effect

The creep model for Zircaloy-4 has been improved by including the metallurgical effect of Zircaloy cladding. Based on the experimental results in which the creep strain rate is highest for stress relief annealed cladding (SRA) and lowest for recrystallized cladding (RXA), the annealing factor was introduced and derived by iterative calculations until the best predictions for all the rods were obtained. The creep model has been incorporated into the KAERIs fuel performance code COSMOS and then verified with 4 cladding creep data, of which 3 cases exhibit creepdown and the other one creepout. The model predicts well the creep behavior of UO2 fuel rods in PWRs. The prediction does not show any discernable difference between the high- and low-Sn claddings. With satisfactory agreement between predicted and measured values, the comparison indicates no difference in creep behavior between MOX and UO2 fuel rods as expected. Although there are controversies over the experimental method and t he analysis procedures for clad creepout, COSMOS generally well predicts the creep behavior, even in the case of creepout, if the creepout factor is applied.close12