SQP 기법에 의한 트러스의 최적화 설계

박재형 牧園大學校 建築·都市硏究센터 1997 建築·都市環境硏究 Vol.5 No.-

The objective of this work is to present an formulation to solve structural optimization problems of trusses. Basically this algorithm use SQP method. Unfortunately, the problem of optimizing structural has very challenging, especially the structural problem of optimizing the highrized buildings. It leads to optimization problems with tens of thousands (or more) of nonlinear constraints, which until recently have been out of the reach of nonlinear numerical optimization methods. Furthermore, commonly-available computers have not been powerful enough to warrant such an approach. This SQP method, therefore, has to be modified to apply to structural optimization problems. We pursue a decomposition of the problem into the state space and the sizing space, as follows: solve at each iteration the discrete equilibrium equations (Ku=P) for the state variables (u: displacement) given values of the sizing variables (A: section area). Thus, we eliminate the state equations (equilibrium equation) from the equality constraint set, and we eliminate the state variables from the set of optimization variables. As a result of this decomposition, although the state variables becomes an implicit function of the sizing variables, the dimension of the optimization problem can be greatly reduced. The examples demonstrate that the formulation presented in this study is effective for finding optimal solution to minimize the weight of structures.

트러스의 위상학적 최적화

박재형 牧園大學校 建築·都市硏究센터 1999 建築·都市環境硏究 Vol.7 No.-

구조물에 있어서 위상학적 최적화 문제는 최적화를 구하는 과정에서 구조체가 변화함으로 인한 어려움 때문에 최적화 분야세서 가장 어려운 문제로 간주되어왔다. 종래의 방법으로는 일반적으로 구조 요소 사이즈가 영으로 접근할 때 강성 매트릭스의 sigularity를 발생시킴으로써 최적의 해를 얻지 못하고 도중에 계산이 종료되어 버린다. 본 연구에 있어서는 이러한 문제점들을 해 결하기 위한 비선형 프로그래밍 formulation을 제안하는 것을 목적으로 한다. 이 formulation의 주된 특성은 요소 사이즈가 영이 되는 것을 허용한다. 평형 방정식을 등제약조건으로 간주함으로써 강성 매트릭스의 singularity를 피할 수 있다. 이 formulation을 하중을 받는 구조물에 있어서 응력과 변위의 제약조건하에서 중량을 최소화할 때의 부재의 단면적을 구하는 디자인 문제에 적용하여, 이 formulation이 위상학적 최적화에 있어서의 효과를 입증하였다.

중추에서 Prostaglandin계가 Renin-angiotensin System에 미치는 영향

최영태,김종승,문성호,오형균,김재훈,전제열,염철호,윤평진 朝鮮大學校 附設 醫學硏究所 1997 The Medical Journal of Chosun University Vol.22 No.1

Role of prostaglandins on the renin-angiotensin system in the central nervous system was examined in normotensive and 2-kidney, 1 clip (2K1C) hypertensive rats. The experiment was done under thiopental (50 ㎎/㎏, IP) anesthesia. Captopril and indomethacin were injected into the right lateral cerebral ventricle. Arterial blood pressure and heart rate were recorded from the femoral artery. Intracerebroventricular (ICV) captopril (1 ㎎) caused a decrease in mean arterial pressure in both normotensive and 2K1C hypertensive rats. The depressor response to captopril was more sensitive in hyper-tensive rats than in normotensive rats. Indomethacin treatment (ICV, 200 ㎎) altered the depressor response to captopril neither in normotensive nor in hypertensive rats. These results suggest that the cardiovascular effect of renin-angiotensin system in the central nervous system may not be mediated via prostaglandin systems in normotensive and 2KlC hypertensive rats.

시스템 가설재의 구조성능 평가에 관한 연구

김성수,안용선,박재형,이재연 牧園大學校 建築·都市硏究센터 1999 建築·都市環境硏究 Vol.7 No.-

This paper describes analysis and test procedures for the estimation of structural performance of SSPS system(Systematic Steel Pipe supporting system) developed through previous researches. Section of each members which composes proposed SSPS system has large influence on weight and capacity of steel pipe supports. Therefore, parameter analysis using the program will be first performed to decide the shapes and details of SSPS system that is light-weighted for easy carrying, setup, dismantling and has high capacity. For evaluation of structural performance of proposed SSPS system, several experiments is carried out under various assembling conditions.

Case series of keratitis in poultry abattoir workers induced by exposure to the ultraviolet disinfection lamp

Do-Hyeong Kwon,Jai-Dong Moon,Won-Ju Park,Won-Yang Kang,Soo-Hyeon Kim,Hyeong-Min Lim,Ji-Sung Ahn,Hong-Jae Chae 대한직업환경의학회 2016 대한직업환경의학회지 Vol.28 No.-

Background: An outbreak of eye diseases occurred among workers at a poultry abattoir in South Korea from December 2012 to June 2013. An epidemiological investigation of the causative agent was conducted. The workers were given a special health examination and workplace environmental monitoring was performed. Workers with ocular symptoms subsequently underwent an ophthalmic examination. Case Presentaion: From a total of 41 workers, 26 (63.4 %) were diagnosed with keratoepitheliopathy by ophthalmic examination. Environmental monitoring of the workplace revealed that the ultraviolet (UV) apron-disinfection lamp had not been turning off at the set times, and so the workers’ faces had been exposed to UV radiation. Effective radiation dose measurement showed a UV-B exposure of 7-30 ㎼/㎠, and a UV-C exposure of 40-200 ㎼/㎠; both values exceed the occupational exposure limits. The outbreak ceased after the lamp was repaired. Conclusions: This case shows that inappropriate use of the UV disinfection lamp can cause mass photokeratitis. In order to prevent this, the UV disinfection lamp must be checked regularly, workers must be educated on the health effects of UV radiation, and appropriate eye protection must be worn.

Topol여cal Structural Optimization under Multiple-Loading Conditions

Bark Jai Hyeong,Hong Soon Jo,Lee Li Hyung 한국전산구조공학회 1996 한국전산구조공학회논문집 Vol.9 No.3

본 연구에서는 :1[조처l 의 우l 상학적 최서화플 위한 비선형 formulation (NLP )가 개발, 검토되었다. 이 NLP 는 multiple-loading 하에샤 염악의 ~Ç> __ ti.젝E] _tl_ 함수, 응력, 맨위 제약조간단블 쉽게 다붙 수가 있다. 또한 이 NLP 는 해삭파 최석화 디자인블 농사에 실시함으보써 요소 사이즈가 영 P 료 집까함에 따른 강성 매트린스의 singularity플 피한 수 있다. 즉, 평형 방정삭블 등제약조끼으로 치흰함으깊써 강성 1깨트릭스 그자체나 그의 역매트박스륜 구한 펀요도 없어진다 이 NLP 든 multiple-loading condition 하에서 테 스트 되었으며, 이플 풍 해 이 NLP 가 다양한 세약조건하에서 강략하셰 작용함이 입증되었다- A simple nonlinear programming (NLP) formulation for the optimal topology problem of structures is developed and examined. The NLP formulation is general, and can handle arbitrary objective functions and arbitrary stress, displacement constraints under multiple loading conditions. The formulation is based on simultaneous analysis and design approach to avoid stiffness matrix singularity resulting from zero sizing variables‘ By embedding the equilibrium equations as equality constraints in the nonlinear programming problem, we avoid constructing and factoring a system stiffness matrix, and hence avoid its singularity. The examples demonstrate that the formulation is effective for finding an optimal sol ution, and shown to be robust under a variety of constraints. Keywords : topology, optimization, nonlinear programming formulation(NLP) , simultaneous method, SQP, single-loading condition, multiple-loading conditions

Large-scale SQP Methods for Optimal Control of steady Incompressible Navier-Stokes Flows

Bark, Jai-Hyeong,Hong, Soon-Jo Computational Structural Engineering Institute of 2002 한국전산구조공학회논문집 Vol.15 No.4

본 연구의 목적은 Navier-Stokes 유체와 같은 대용량 문제를 위한 최적화 기법의 개발에 있다. 이를 위해 본 연구에서는 reduced Hessian sequential quadratic programming을 개발하였다. 첫째, 유체의 해석을 위한 평형 방정식을 최적화 과정에서 제거하여 변수를 줄였고, 또한 평형방정식과 최적화 과정에서 연속기법을 사용하여 최적해를 보장하면서 더욱 해에 쉽게 접근하도록 하였다. 그리고 각 단계에서는 테일러 시리즈를 이용한 근사치를 이용하여 각 단계에서 대단히 좋은 초기치 값을 제공하여 최적해에 더욱 빠르게 접근하게 하고 아울러 유체의 평형방정식을 풀 때에도 해에 더욱 빠르고 쉽게 접근하도록 하였다. 이 기법을 항력을 줄이기 위한 유체의 최적 제어를 위한 문제에 적용하였다. 유체의 흐름을 제어하기 위하여 물체의 경계면에서 유체의 흡입(suction)과 방축(injection)이라는 기법을 사용하여 경계면에서 속도를 제어하였고, 목적함수로써 항력을 표현하기 위하여 에너지 소실의 변화율을 사용하였다. 예제를 통해 본 연구에서 개발한 최적화 기법의 효용성을 입증하였다. The focus of this work is on the development of large-scale numerical optimization methods for optimal control of steady incompressible Navier-Stokes flows. The control is affected by the suction or injection of fluid on portions of the boundary, and the objective function of fluid on portions of the boundary, and the objective function represents the rate at which energy is dissipated in the fluid. We develop reduced Hessian sequential quadratic programming. Both quasi-Newton and Newton variants are developed and compared to the approach of eliminating the flow equations and variables, which is effectively the generalized reduced gradient method. Optimal control problems we solved for two-dimensional flow around a cylinder. The examples demonstrate at least an order-of-magnitude reduction in time taken, allowing the optimal solution of flow control problems in as little as half an hour on a desktop workstation.

A Nonlinear Programming Formulation for the Topological Structural Optimization

Bark Jai Hyeong,Lee Li Hyung 한국전산구조공학회 1996 한국전산구조공학회논문집 Vol.9 No.3

구조물에 있어서 위상학적 최적화 문제는 최적화를 구하는 과정에서 구조체가 변화함으로 인한 어려웅 때 문에 최적화 분야에서 가장 어려운 문제로 간주되어 왔다. 종래의 방법으로는 일반적으로 구조 요소 사이즈가 영으로 접근할 때 강성 매트릭스의 singularity를 발생시킴으로써 최적의 혜를 얻지 못하고 도중에 계산이 종 료되어 버린다. 본 연구에 있어서는 이러한 문제점들을 해결하기 위한 비선형 프로그래밍 formulation을 제 안하는 것올 목적으로한다. 이 formulation 의 주된 특성은 요소 사이즈가 영이 되는 것을 허용한다. 평형 방정 식 을 둥제 약조건으로 간주함으로써 강성 매 트릭 스의 singularity를 피 할 수 있다. 이 formulation을 하중올 받는 구조물에 있어서 웅력과 변위의 제약조 건 하에서 중량을 최소화할때의 유한 요소의 두께를 구하는 디자 인 문제에 적용하여, 이 formulation 이 위상화적 최적화에 있어서의 효과를 입증하였다. The focus of this study is on the problem of the design of structure of undetermined topology. This problem has been regarded as being the most challenging of structural optimization problems, because of the difficulty of allowing topology to change. Conventional approaches break down when element sizes approach to zero, due to stiffness matrix singularity. In this study, a novel nonlinear programming formulation of the toφlogy problem is presented. Its main feature is the ability to account for topology variation through zero element sizes. Stiffness matrix singularity is avoided by embedding the equilibriurn equations as equahty constraints in the optimization problem. Although the formulation is general, two dimensional plane elasticity examples are presented. The design problem is to find minim띠n weight of a plane structure of fixed geometry but variable topology, subject to constraints on stress and displacement. Variables are thicknesses of finite elements, and are permitted to assume zero sizes. The examples demonstrate that the formulation is effective for finding at least a locally minimal weight.

Implementation of a resident night float system in a surgery department in Korea for 6 months: electronic medical record-based big data analysis and medical staff survey

Hyeong Won Yu,June Young Choi,Young Suk Park,Hyung Sub Park,YoungRok Choi,Sang-Hoon Ahn,Eunyoung Kang,오흥권,Eun-Kyu Kim,Jai Young Cho,Duck-Woo Kim,Do Joong Park,Yoo-Seok Yoon,Sung Bum Kang,Hyung-Ho Kim 대한외과학회 2019 Annals of Surgical Treatment and Research(ASRT) Vol.96 No.5

Purpose: To evaluate superiority of a night float (NF) system in comparison to a traditional night on-call (NO) system for surgical residents at a single institution in terms of efficacy, safety, and satisfaction. Methods: A NF system was implemented from March to September 2017 and big data analysis from electronic medical records was performed for all patients admitted for surgery or contacted from the emergency room (ER). Parameters including vital signs, mortality, and morbidity rates, as well as promptness of response to ER calls, were compared against a comparable period (March to September 2016) during which a NO system was in effect. A survey was also performed for physicians and nurses who had experienced both systems. Results: A total of 150,000 clinical data were analyzed. Under the NO and NF systems, a total of 3,900 and 3,726 patients were admitted for surgery. Mortality rates were similar but postoperative bleeding was significantly higher in the NO system (0.5% vs. 0.2%, P = 0.031). From the 1,462 and 1,354 patients under the NO and NF systems respectively, that required surgical consultation from the ER, the time to response was significantly shorter in the NF system (54.5 ± 70.7 minutes vs. 66.8 ± 83.8 minutes, P < 0.001). Both physicians (90.4%) and nurses (91.4%) agreed that the NF system was more beneficial. Conclusion: This is the first report of a NF system using big data analysis in Korea, and potential benefits of this new system were observed in both ward and ER patient management

Insomnia and hearing impairment among occupational noise exposed male workers

Hyeong-Min Lim,WonYang Kang,Won-Ju Park,Keun-Ho Jang,Ji-Sung Ann,Jai-Dong Moon 대한직업환경의학회 2017 대한직업환경의학회지 Vol.29 No.-

Background: The aim of this study was to investigate the association between insomnia and hearing impairment among workers exposed to occupational noise. Methods: This study included 809 male workers exposed to occupational noise. The participants underwent audiometric testing, and their insomnia was examined based on the Insomnia Severity Index test. Hearing impairment was defined as hearing threshold >25 dB hearing level in the range of 1–4 kHz. Results: According to analysis of covariance, it was observed that pure tone audiometry thresholds at 1–2 kHz in the right ear and at 1 kHz in the left ear were significantly higher among workers with insomnia compared to those with no insomnia. Multiple logistic regression analysis of insomnia for hearing impairments was performed, which showed the odds ratio was 1.806 (95% confidence intervals: 1.022–3.188, p = 0.042) after adjustment for age, working period, noise level, snoring, use of protection devices, diabetes mellitus, hypertension, smoking, alcohol consumption, regular exercise, waist circumference, total cholesterol, triglyceride and high density lipoprotein cholesterol. Conclusion: Insomnia could be associated with hearing impairment in workers who are exposed to occupational noise. Additionally, insomnia may be associated with decreased hearing at low frequencies. Especially, more efforts are required to improve the quality of sleep for workers who are exposed to loud occupational noise. Further welldesigned prospective studies are needed to clarify the relationship between insomnia and hearing impairment.