무인항공기 운영을 위한 덮개 모델 기반의 대규모 최적화 기법

학위논문 (박사) -- 서울대학교 대학원 : 공과대학 산업공학과, 2021. 2. 문일경.There is increasing interest in the unmanned aerial vehicle (UAV) in various fields of the industry, starting from the surveillance to the logistics. After introducing the smart city, there are attempts to utilize UAVs in the public service sector by connecting individual components of the system with both information and physical goods. In this dissertation, the UAV operation problems in the public service sector is modeled in the set covering approach. There is a vast literature on the facility location and set covering problems. However, when operating UAVs in the system, the plan has to make the most of the flexibility of the UAV, but also has to consider its physical limitation. We noticed a gap between the related, existing approaches and the technologies required in the field. That is, the new characteristics of the UAV hinder the existing solution algorithms, or a brand-new approach is required. In this dissertation, two operation problems to construct an emergency wireless network in a disaster situation by UAV and one location-allocation problem of the UAV emergency medical service (EMS) facility are proposed. The reformulation to the extended formulation and the corresponding branch-and-price algorithm can overcome the limitations and improve the continuous or LP relaxation bounds, which are induced by the UAV operation. A brief explanation of the UAV operation on public service, the related literature, and the brief explanation of the large-scale optimization techniques are introduced in Chapter 1, along with the research motivations and contributions, and the outline of the dissertations. In Chapter 2, the UAV set covering problem is defined. Because the UAV can be located without predefined candidate positions, more efficient operation becomes feasible, but the continuous relaxation bound of the standard formulation is weakened. The large-scale optimization techniques, including the Dantzig-Wolfe decomposition and the branch-and-price algorithm, could improve the continuous relaxation bound and reduce the symmetries of the branching tree and solve the realistic-scaled problems within practical computation time. To avoid numerical instability, two approximation models are proposed, and their approximation ratios are analyzed. In Chapter 3, UAV variable radius set covering problem is proposed with an extra decision on the coverage radius. While implementing the branch-and-price algorithm to the problem, a solvable equivalent formulation of the pricing subproblem is proposed. A heuristic based on the USCP is designed, and the proposed algorithm outperformed the benchmark genetic algorithm proposed in the literature. In Chapter 4, the facility location-allocation problem for UAV EMS is defined. The quadratic variable coverage constraint is reformulated to the linear equivalent formulation, and the nonlinear problem induced by the robust optimization approach is linearized. While implementing the large-scale optimization techniques, the structure of the subproblem is analyzed, and two solution approaches for the pricing subproblem are proposed, along with a heuristic. The results of the research can be utilized when implementing in the real applications sharing the similar characteristics of UAVs, but also can be used in its abstract formulation.현재, 지역 감시에서 물류까지, 무인항공기의 다양한 산업에의 응용이 주목받고 있다. 특히, 스마트 시티의 개념이 대두된 이후, 무인항공기를 공공 서비스 영역에 활용하여 개별 사회 요소를 연결, 정보와 물자를 교환하고자 하는 시도가 이어지고 있다. 본 논문에서는 공공 서비스 영역에서의 무인항공기 운영 문제를 집합덮개문제 관점에서 모형화하였다. 설비위치결정 및 집합덮개문제 영역에 많은 연구가 진행되어 있으나, 무인항공기를 운영하는 시스템의 경우 무인항공기가 갖는 자유도를 충분히 활용하면서도 무인항공기의 물리적 한계를 고려한 운영 계획을 필요로 한다. 우리는 본 문제와 관련된 기존 연구와 현장이 필요로 하는 기술의 괴리를 인식하였다. 이는 다시 말해, 무인항공기가 가지는 새로운 특성을 고려하면 기존의 문제 해결 방법을 통해 풀기 어렵거나, 혹은 새로운 관점에서의 문제 접근이 필요하다는 것이다. 본 논문에서는 재난이 발생한 지역에 무인항공기를 이용하여 긴급무선네트워크를 구성하는 두가지 문제와, 무인항공기를 이용하여 응급의료서비스를 제공하는 시설의 위치설정 및 할당문제를 제안한다. 확장문제로의 재공식화와 분지평가법을 활용하여, 무인항공기의 활용으로 인해 발생하는 문제 해결 방법의 한계를 극복하고 완화한계를 개선하였다. 공공 서비스 영역에서의 무인항공기 운영, 관련된 기존 연구와 본 논문에서 사용하는 대규모 최적화 기법에 대한 개괄적인 설명, 연구 동기 및 기여와 논문의 구성을 1장에서 소개한다. 2장에서는 무인항공기 집합덮개문제를 정의한다. 무인항공기는 미리 정해진 위치 없이 자유롭게 비행할 수 있기 때문에 더 효율적인 운영이 가능하나, 약한 완화한계를 갖게 된다. Dantzig-Wolfe 분해와 분지평가법을 포함한 대규모 최적화 기법을 통해 완화한계를 개선할 수 있으며, 분지나무의 대칭성을 줄여 실제 규모의 문제를 실용적인 시간 안에 해결할 수 있었다. 수치적 불안정성을 피하기 위하여, 두 가지 선형 근사 모형이 제안되었으며, 이들의 근사 비율을 분석하였다. 3장에서는 무인항공기 집합덮개문제를 일반화하여 무인항공기 가변반경 집합덮개문제를 정의한다. 분지평가법을 적용하면서 해결 가능한 평가 부문제를 제안하였으며, 휴리스틱을 설계하였다. 제안한 풀이 방법들이 기존 연구에서 제안한 벤치마크 유전 알고리즘을 능가하는 결과를 나타내었다. 4장에서는 무인항공기 응급의료서비스를 운영하는 시설의 위치설정 및 할당문제를 정의하였다. 2차 가변반경 범위제약이 선형의 동치인 수식으로 재공식화되었으며, 강건최적화 기법으로 인해 발생하는 비선형 문제를 선형화하였다. 대규모 최적화 기법을 적용하면서, 평가 부문제의 구조를 분석하여 두 가지 풀이 기법과 휴리스틱을 제안하였다. 본 연구의 결과는 무인항공기와 비슷한 특징을 가지는 실제 사례에 적용될 수 있으며, 추상적인 문제로써 다양한 분야에 그대로 활용될 수도 있다.Abstract i Contents vii List of Tables ix List of Figures xi Chapter 1 Introduction 1 1.1 Unmanned aerial vehicle operation on public services 1 1.2 Facility location problems 3 1.3 Large-scale optimization techniques 4 1.4 Research motivations and contributions 6 1.5 Outline of the dissertation 12 Chapter 2 Unmanned aerial vehicle set covering problem considering fixed-radius coverage constraint 14 2.1 Introduction 14 2.2 Problem definition 20 2.2.1 Problem description 22 2.2.2 Mathematical formulation 23 2.2.3 Discrete approximation model 26 2.3 Branch-and-price approach for the USCP 28 2.3.1 An extended formulation of the USCP 29 2.3.2 Branching strategies 34 2.3.3 Pairwise-conflict constraint approximation model based on Jung's theorem 35 2.3.4 Comparison of the approximation models 40 2.3.5 Framework of the solution algorithm for the PCBP model 42 2.4 Computational experiments 44 2.4.1 Datasets used in the experiments 44 2.4.2 Algorithmic performances 46 2.5 Solutions and related problems of the USCP 61 2.6 Summary 64 Chapter 3 Unmanned aerial vehicle variable radius set covering problem 66 3.1 Introduction 66 3.2 Problem definition 70 3.2.1 Mathematical model 72 3.3 Branch-and-price approach to the UVCP 76 3.4 Minimum covering circle-based approach 79 3.4.1 Formulation of the pricing subproblem II 79 3.4.2 Equivalence of the subproblem 82 3.5 Fixed-radius heuristic 84 3.6 Computational experiments 86 3.6.1 Datasets used in the experiments 88 3.6.2 Solution algorithms 91 3.6.3 Algorithmic performances 94 3.7 Summary 107 Chapter 4 Facility location-allocation problem for unmanned aerial vehicle emergency medical service 109 4.1 Introduction 109 4.2 Related literature 114 4.3 Location-allocation model for UEMS facility 117 4.3.1 Problem definition 118 4.3.2 Mathematical formulation 120 4.3.3 Linearization of the quadratic variable coverage distance function 124 4.3.4 Linear reformulation of standard formulation 125 4.4 Solution algorithms 126 4.4.1 An extended formulation of the ULAP 126 4.4.2 Branching strategy 129 4.4.3 Robust disjunctively constrained integer knapsack problem 131 4.4.4 MILP reformulation approach 132 4.4.5 Decomposed DP approach 133 4.4.6 Restricted master heuristic 136 4.5 Computational experiments 137 4.5.1 Datasets used in the experiments 137 4.5.2 Algorithmic performances 140 4.5.3 Analysis of the branching strategy and the solution approach of the pricing subproblem 150 4.6 Summary 157 Chapter 5 Conclusions and future research 160 5.1 Summary 160 5.2 Future research 163 Appendices 165 A Comparison of the computation times and objective value of the proposed algorithms 166 Bibliography 171 국문초록 188 감사의 글 190Docto

Influence on the meridian electrical potential for ground connection and insulation in acupuncture practice

의공학전공/석사[한글]침술과정의 시술상황은 전기학적 관점에서 전기회로의 형성 여부에 따라 치료 효과를 저하시키는 원인이 될 수 있다. 이에 대하여, 환자와 시술자의 접지나 절연과 같은 시술상황 모델을 통해, 접지와 절연이 침 자극에 의한 경락의 전위차 형성 정도에 어떠한 영향을 주는지 관찰하였다.실험방법은 20대(26세 ± 5.3) 남녀 각각 15명씩 30명을 대상으로 동일인이 시술하였다. 하거허(S39)와 상거허(S37)에 자침하여 상거허에 (+)전극을, 하거허에 (-)전극을 연결하여 족삼리(S36)를 타침 자극한 뒤 두 경혈간의 전위를 측정하였다. 우선 비절연 자침으로 자극하면서 모두 비접지, 시술자 접지, 환자 접지, 모두 접지에 따른 전위변화를 측정하였다. 이후 절연 자침을 동일한 방식으로 측정하였다.측정데이터를 통계 처리한 결과, 비절연 모두 비접지는 평균 전위 44.6±19.2㎶로 양(+)의 방향으로 증가하였으며, 침을 잡았다 놓는 순간에 발생하는 peak간 전위는 181.4±59.7㎶로 증가하였다. 피시술자만 접지한 경우는 평균 전위 2.9±1.3㎶, peak간 전위는 16.4±11.9㎶로 침자극에 대한 유의한 전위변화가 나타나지 않았다. 시술자만 접지한 경우는 평균 전위는 -51.1±9.3㎶로 음(-)의 방향으로 증가하였고, peak간 전위는 367.4±27.8㎶로 침자극에 대한 가장 큰 전위의 변화가 관찰되었다. 모두 접지는 평균전위 1.6±0.7㎶, peak간 전위는 3.3±1.9㎶로 전위변화가 나타나지 않았다. 절연 자침시, 모든 경우에서 일정한 방향으로 지속하는 평균 전위 형성은 없었다. peak간 전위는 모두 비접지시 7.8±2.6㎶, 피시술자 접지시 4.7±2.2㎶, 시술자 접지시 8.4±2.5㎶, 모두 접지시 3.4±1.4㎶를 보였다.따라서, 침술과정에서 시술자와 피시술자간의 전기적 접지조건과 절연상태에 따라 피시술자의 경락전위변화에 미치는 영향이 다름을 확인하였다. 이러한 조건이 전기적 관점에서, 침술효과에 직·간접적으로 영향을 줄 것으로 사료된다. 또한, 시술자와 환자간의 접지여부는 생체 전위차 및 방향을 결정하며, 절연자침은 시술자와 환자간의 미세한 정전기적인 전위를 발생시킬 뿐, 이외의 생체에너지 전달을 차단하는 원인으로 경락전위에 대한 영향이 미약함을 확인하였다. [영문]Background: When a patient is positioned at insulated bed and practitioner is positioned at insulated floor, that condition could be a cause of lessening effect in acupuncture practice. We investigated how Ground connection and Insulation could influence on the electrical meridian potential between practitioner and patient during acupuncture practice.Method: We treated 30 normal healthy subjects with acupuncture and measured changes in the electrical potential between the stomach meridian points ST-39 and ST-37 in response to light touch after insertion of a needle at ST-36. At first, we stimulated non-insulated needle and measured electrical potentials for non ground, patient ground only, practitioner ground only, all ground, respectively. Then we used insulated needles and measured same as above.Result: Non-insulated all ground subject elicited positive mean potential 44.6±19.2㎶ and showed 181.4±59.7㎶ peak to peak potential. Practitioner ground only showed negative mean potential of -51.5±9.3㎶ and 367.4±27.8㎶ of peak to peak potential. Patient ground only revealed no mean potential of 2.9±1.3㎶, 16.4±11.9㎶ of peak to peak potential. All ground showed no mean potential of 1.6±0.7㎶, 3.3±1.9㎶ of peak to peak potential. In case of Insulated condition, there elicited no mean potential. Non ground and Practitioner only showed weak value of peak to peak potential as 7.8±2.6㎶ and 8.4±2.5㎶ each. But patient only and all ground showed no potential as 4.7±2.2㎶, 3.4±1.4㎶, respectively.Conclusion: Ground connection modulate the energy transfer course between practitioner and patient. Insulation block energy transfer but static electrical impulse between practitioner and patient.ope

경인교육대학교 유휴부지를 중심으로

학위논문 (석사) -- 서울대학교 대학원 : 환경대학원 환경조경학과, 2020. 8. 성종상.근대화 과정에서 발생한 채석장은 국가 산업발전에 기여하였으나 개발이 완 료된 후 기능을 다해 쇠퇴·폐쇄되어 방치된 상태에서 나타나는 도시·환경· 사회문제에 대한 해결하기 위한 해법을 찾고자하였다. 채굴이 완료된 채석장은 법적으로 「산지관리법」제4장 39조1)에 따라 원상 태로 복구해야 한다. 그러나 복구방식에 있어 적절한 복구를 하였다 하더라도 원상태로 복구하기 어려우며 이는 막대한 복구비용 가져온다. 따라서 대부분 의 채석장은 적절한 복구가 이루어지지 않고 있으며 방치되고 있다. 방치된 흉물은 주변 경관의 기능을 저하시키며 주변발전에 저해하는 요소로 작용한 다. 그러나 최근 방치된 채석장을 활용하여 공원 및 문화공간을 조성하고 있 는 사례가 있다. 대표적인 예로는 포천아트밸리를 들 수 있으며 이러한 시도 는 과거 부정적 이였던 채석장을 관광명소로 활용함으로서 지역경제활성에 큰 도움을 주고 있는 실정이다. 안양시 석수동에 위치한 본 연구의 대상지는 아파트공사에 쓰일 자갈을 공 수하기 위해 1979년부터 개발을 시작하였고 1995년 채석작업이 완료됨과 동시 에 복구공사가 진행되었다. 2005년 기존 채석장 부지에는 경인교육대학교가 건립되었고, 건립과정에서 여러 환경문제들이 발생하였다. 그러나 이런 문제들 을 개선하기 위해 학교에서는 끊임없는 노력을 하였고 현재는 개선된 유휴부 지로 남아있다. 따라서 본 연구에서는 과거 채석활동으로 환경문제의 이슈의 공간이었지만 현재 시점에서는 주요 공간으로 활용하여 인식의 전환의 계기가필요하다고 판단했다. 연구를 진행하기에 앞서 채석장에 대한 전반적인 이해 를 하기위해 선행연구를 진행 하였다. 선행연구는 큰 범주에서 채석장과 유사 개념의 공간에 대한 활용방안을 조사하였고, 이에 맞는 이용자 즉 시민에 대 한 인식조사를 초점으로 두었다. 이론적 고찰은 폐채석장의 활용필요성에 대한 개념과 이를 보존하며 활용하는 범주에서 산업유산에서의 채석장이 갖 고 있는 개념을 고찰하였다. 폐채석장을 활용하는데 있어 반드시 준수해야하는 법과 관련 규제들을 살 펴보았으며 국내 문헌들을 바탕으로 설계 및 시공 과정에 대해서 고찰하였다. 본격적으로 대상지를 이해하기 위해 큰 스케일의 개념의 전반적인 이해를 하였으며 유래와 변천과정을 통해 과거 대상지 주변부에서 일어난 주요 사건 들을 살펴보았다. 인구현황 분석을 통해 만안구 석수동에 대한 인구현황, 연 령, 직업등을 조사하였으며 앞선 주요내용을 바탕으로 실질적으로 지역 관련 주체들이 갖고 있는 인식들이 어떠한지에 대한 설문조사와 인터뷰를 바탕으로 공원의 타당성을 정립하였으며, 어떤 방향으로 이용되어야 하는지에 대한 의견을 들을 수 있었다. 대상지분석을 통해 대 고찰 후 대상지의 문제점 및 활용방향을 파악하기 위해 대상지의 유래와 근대 변천과정을 통해 대상지 과거의 사회적인 이슈들 을 살펴보았으며, 현재 대상지가 소속해 있는 만안구 석수동에 대한 인구현황 분석을 통해 전반적인 시민들의 연령, 직업 등을 살펴보았다. 대상지 분석을 통해 거시적인 맥락에서 대상지의 입지적 요소들을 파악하 였으며, 세부적인 분석을 통해 실질적으로 대상지가 갖고 있는 주요 현황과 문제점들 도출하였다. 이 외 독립적인 요소로서 작용하는 공간이 아닌 만큼 조성 과정에 있어 주변일대에 진행되고 있는 관련계획들을 살펴봄으로써 대상 지 조성에 있어 연계 가능한 요소들을 도출하였다. 위의 분석내용을 기반으로 본 연구의 설계목표를 설정하였다. 단절된 절 개면의 연결성을 강화시키기 위한 방안을 제안하며. 관광지로 기능을 하는 공원을 조성하여 지역 경제활성 및 커뮤니티 공간으로 활용될 수 있는 공간조 성, 채석장이 갖는 절개지의 특색을 활용할 수 있는 방안마련과 과거 채석활 동으로 인해 황폐화된 토지를 복원하며 주변산림과 어울리는 공간조성을 본 연구의 목표로 설정하였다. 본 연구는 채석장이 갖고 있는 부정적 인식을 전환하는 방안의 일환으로서 공원 조성을 제안하며 초기 공원을 조성하는데 있어 주변 관련주체의 의견을 반영함으로서 참여하고, 성장하는 공원이라는 점에서 차별성이 있으며 이 후 폐채석장을 활용하는 기초자료로 활용 할 수 있다는데 점에서 의의가 있 다.The quarry that occurred during the modernization process contributed to the development of the national industry, but after the development was completed, it was intended to find a solution to solve the urban, environmental and social problems that appear in the state of decline and closure. The quarry where the mining is completed shall be restored to its original state in accordance with Act 4 of the Mountainous Districts Management Act. However, even if proper restoration is done in the restoration method, it is difficult to restore it to its original state, which brings huge recovery costs. Therefore, most quarry is not properly restored and is neglected. Left unattended scars degrade the function ofthe surrounding landscape and hinder its development. However, there are cases where parks and cultural spaces are being created using recently neglected quarry. A typical example is Pocheon Art Valley, which is a great help to revitalize the local economy by using quarry, which was a negative in the past, as a tourist attraction. The target area of this study located in Seoksu-dong, Anyang-si started development in 1979 to airlift gravel to be used for apartment construction. In 1995, the quarrying work was completed and the restoration work was carried out. In 2005, Gyeongin National University of Education was established on the existing quarry site, and various environmental problems occurred during the construction process. However, in order to improve these problems, the school has made constant efforts and now remains an improved abandoned site. Therefore, this study was a space of environmental issues as a quarrying activity in the past, but at this point, it was judged that it is necessary to use it as a major space and to change the awareness. Prior to the study, previous studies were conducted to understand the quarry in general. Previous studies have investigated the utilization plan of quarry and similar concept space in a large category, and focused on the survey of users, citizens, and the survey of the perception. The theoretical consideration was to examine the concept of 'the necessity of using waste quarries' and the concept of quarries in industrial heritage in the category of preserving and utilizing them. The laws and related regulations that must be observed in the utilization of waste quarry were examined, and the design andconstruction process were considered based on domestic literature. In order to understand the object in earnest, the overall understanding of the concept of large scale was made, and major events that occurred in the periphery of the object were examined through the origin and transition process. The population status, age, occupation, etc. were investigated through the analysis of population status. Based on the main contents, the validity of the park was established based on the survey and interview on the perceptions of local subjects, and opinions on 'what direction should be used' were heard. After the analysis of the target area, the social issues of the target area were examined through the origin of the target area and the process of modern change in order to grasp the problems and utilization direction of the target area. The age and occupation of the citizens were examined through the analysis of the population status of Seoksu-dong, Manan-gu, where the target area belongs. Through the analysis of the target site, the locational elements of the target site were identified in macroscopic contexts, and the main current status and problems of the target site were derived through detailed analysis. In addition, as it is not a space that acts as an independent element, it has derived the elements that can be linked to the creation of the target area by examining the related plans that are being carried out in the surrounding area. Based on the above analysis, the design goal of this study was set up, and a plan to strengthen the connectivity of the cut-out surface was proposed. The purpose of this study was to create a park that functions제1장 서론 1절. 연구의 배경 및 목적 1 1. 연구의 배경 1 2. 연구의 목적 3 2절. 연구의 범위 4 1. 공간적 범위 4 2. 내용적 범위 및 진행과정 5 3절. 선행연구의 고찰 7 4절. 연구의 차별성 10 제 2장 이론적 고찰 1절. 폐채석장 활용의 이해 11 1. 산업유산개념의 채석장 이해와 활용의 필요성 11 2. 폐채석장의 복구기준 및 복원과정 14 3. 폐채석장의 복원 설계 및 시공 18 2절. 사례연구 23 제 3장 대상지 분석 1절. 대상지의 이해 31 1. 대상지 개요 31 2. 대상지의 유래와 변천과정 32 3. 인구현황 39 2절. 공원화의 타당성 및 주민의견 42 1. 관련법률 검토 및 공원의 타당성 42 2. 지역주민 의견 44 3절. 대상지 분석 49 1. 거시적 맥락의 분석 49 2. 세부 대상지 분석 55 4절. 관련계획 검토 72 5절. 종합분석 75 제 4장 기본방향 및 구상 1절. 기본방향 79 1. 지형을 고려한 설계방안 도입 79 2. 관련 사업 및 주변 인프라와의 연계 81 3. 지역 주체의 의견 수렴 82 2절. 설계의 목표 82 3절. 기본 구상 84 제 5장 기본계획 및 설계 1절. 기본계획 87 1. 종합계획도 87 2. 동선계획 88 3. 포장계획 89 4. 식재계획 89 5. 프로그램계획 94 2절. 세부공간별 설계 96 1. 연결타워 및 레저센터 95 2. 상부 연결로 및 중앙보행로 97 3. 절개면 상부 공간 및 쉼터 99 4. 커뮤니티정원 및 서비스시설 100 제 6장 결론 [참고문헌] 104 [Abstract] 106Maste

Current Status of Home Visit Programs: Activities and Barriers of Home Care Nursing Services

PURPOSE: The purpose of this study was to examine the current status of home care nursing services provided by community health nurses and to identify barriers to the services. METHODS: A cross-sectional survey was conducted with three types of community health care nurses. Participants were 257 nurses, 46 of whom were hospital based home care nurses, 176 were community based visiting nurses, and 35 were long term care insurance based visiting nurses. A structured questionnaire on 7 domains of home care nursing services with a 4-point Likert scale was used to measure activities and barriers to care. Data were analyzed using SPSS WIN 21.0 program. RESULTS: Hospital based home care nurses showed a high level of service performance activity in the domain of clinical laboratory tests, medications and injections, therapeutic nursing, and education. Community based visiting nurses had a high level of service performance in the reference domain. Long term care insurance based visiting nurses showed a high level of performance in the service domains of fundamental nursing and counseling. CONCLUSION: The results show that although health care service provided by the three types of community health nurse overlapped, the focus of the service is differentiated. Therefore, these results suggest that existing home care services will need to be utilized efficiently in the development of a new nursing care service for patients living in the community after hospital discharge.ope

The Effect of Self-Expanding Metallic Stent Insertion for the Treatment ofMalignant Colorectal Obstruction

BACKGROUND/AIMS: The aim of this study was to evaluate the clinical and cost effectiveness of the use of stent insertion for malignant colorectal obstruction as compared with performing emergency surgery. METHODS: We retrospectively reviewed the medical records of 201 patients. Malignant colorectal obstructions caused by a resectable tumor were treated with preoperative stenting followed by surgery (group A, n=55) or emergency surgery (group B, n=59). Malignant obstructions caused by an unresectable cancer were treated with palliative stenting (group C, n=58) or palliative emergency surgery (group D, n=29). RESULTS: The one-staged radical resection rate was significantly higher in group A patients than in group B patients (87.3% vs. 52.5%, p<0.05). Post-operative complications were more frequent in group A patients than in group B patients (9.1% vs. 32.2%, p<0.05). The admission period was significantly shorter for group A patients than for group B patients (25.0 days vs. 33.7 days, p<0.05). The medical cost was not different for group A and group B patients. Life-long stoma formation was necessary for 15.5% of group C patients and 69% of group D patients, respectively. The admission period was significantly shorter for group C patients than group D patients (10.5 days vs. 22.7 days, p<0.05). The medical cost was not different for group C and D patients. CONCLUSIONS: Stent insertion was an effective treatment modality for malignant colorectal obstruction.ope

담관협착의 감별과 간외담도암의 병기 결정에서의 IDUS의 역할

ope

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

Changes of Ascites Nitric Oxide According to the Treatment Course in Cirrhotic Patients with Spontaneous Bacterial Peritonitis

Background/Aims: Nitricoxide (NO) is a molecule involved in vascular dilatation and pathogen suppression. It also has immunologic and regulatory functions. Liver cirrhosis is characterized by an increased risk for bacterial infections, including spontaneous bacterial peritonitis (SBP). The role of NO in SBP which develops in cirrhosis has not been clearly established. The aim of this study was to investigate the role of NO in the pathogenesis of SBP and its clinical usefulness for prediction of disease prognosis. Methods: This study was designed to investigate the changes of ascites NO in the course of treatment. Nitricoxide metabolite (nitrites+nitrates [NO x]) was measured by chemilum inescence in 84 ascites samples obtained from 84 cirrhotic patients. Among them , the 38 patients with SBP were treated with cefotaxim e 2.0 g, q 12hr for 7 days. In 24 of SBP patients, ascites was obtained consecutively before treatment (day 0),during treatment (day 2),and after treatment (day 7). Results: Ascites NO levels in the patients w ith SBP (n=38; 82.3 14.4 μM ) were not different from those in patients with sterile ascites (n=46; 54.6 13.0 μM ). There was no significant change of NO levels in sequential ascites samples during antibiotic treatment. A scites NO level before treatment was significantly higher in SBP patients who responded to antibiotics (n=26; 101.86 μM/L) than that in SBP patients who did not respond to antibiotics (n=12; 40.03 μM/L, P =0.044). A significant direct correlation was found between ascites and serum NO levels before treatment (Pearson correlation,r2=0.86,P =0.001). Among the SBP patients, treatment response rate to antibiotics were significantly higher in those patients with pretreatment NO level≥80 μM/L in multivariate analysis. Conclusions: Ascites NO level was not different between ascites from SBP patients and ascites from cirrhotic patients with sterile ascites. There were no changes of ascites NO in SBP patients during treatment. Therefore ascites NO was not useful to predict the progress of SBP. Ascites NO levels reflect serum NO levels, and the patients with higher NO level may have better response to antibiotics.ope

Improvement of Dynamic Encoding Algorithm for Search using history information

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Expression of CD99 in human plasma cells and its biologic implication

학위논문(박사) --서울대학교 대학원 :의학과 (병리학 전공),2009.2.Docto