순 방사형 물류체계에서 수송장비의 보유대수 결정과 분배정책 : 복합포아송과정을 따를 경우 The Case of Compound Poisson Process

서순근,이병호 한국경영과학회 1999 韓國經營科學會誌 Vol.24 No.3

Fleet sizing and empty equipment redistribution are two of the most critical problems in managing a fleet of equipment over a transportation network. Where the demand pattern followed the compound Poission process(CPP) which can be generated one or more at a time under homogeneous Poissio process(HPP), this paper presented a mathematical model to determine control parameters of a decentralized distribution policy and fleet size. In case of the pure hub-and-spoke system, a popular form of a logistics system, and validated this model by simulation. That is, where the number of demanded equipments followed geometric and binomial distribution, respectively, cost models on the pure hub-and-spoke logistics system with deterministic transportation time, which could be solved analytically, were established and analyzed. We also compared the deterministic case with stochastic one that the transportation time follows some probability distributions.

피로곡선 모형의 통계적 분석 및 비교

서순근,조유희 한국품질경영학회 2003 품질경영학회지 Vol.31 No.2

The fatigue has been considered to the most important failure mode where optimal design or reliability prediction of the machinery in aircraft, atomic reactors, and structure systems, etc.. is required. When the statistical analysis of fatigue life data is performed, some difficulties are present because of the following facts : nonlinear relationship, heteroscedastic data, large scatter in the data, censored data (runouts), and existence of fatigue limit. To find the S-N curve models that characterize fatigue strength better, this research compares existing fatigue curve models developed recently in terms of the residual mean square and the estimate of fatigue limit, etc. for various fatigue data sets.

100% 선별검사를 고려한 허용차의 결정

徐洵根,鄭原基 동아대학교 공과대학 부설 한국자원개발연구소 1994 硏究報告 Vol.18 No.2

This paper presents an economic model to determine producer's tolerance factor of a quality characteristic with 100% screening inspection on the assumptions of continuous quadratic loss function and linear inspection cost. A solution procedure for the optimum tolerance is developed and illustrated with a numerical example. Taguchi's tolerance determining procedure have been analyzed in the framework of western statistical quality control although Taguchi has derived tolerances with the consideration of quadratic loss function and deterministic quality characteristic.

수명이 지수분포를 따를 때 정기검사 및 정시종결하에서 신뢰성 샘플링검사계획의 개발

서순근,김갑석 한국경영과학회 1996 한국경영과학회지 Vol.21 No.1

A Reliability Acceptance Sampling Plan(RASP) is developed for testing the exponential mean lifetime under the periodic(i. e., equally-spaced) inspection and Type I censoring. Under the periodic inspection, the exact sampling distribution of maximum likelihood(ML) estimator of mean can not be derived. Hence sample size and acceptance criterion are determined by the algorithm proposed on the basis of Monte Carlo simulation such that the producer's and consumer's risks are satisfied for given censoring time and number of inspections. In addition, the developed RASP is compared to other RASP's designed under the continuous inspection and under the periodic inspection in terms of sampling size, OC curve, and expected completion time, The effects for the RASP by the chosen inspection scheme are also discussed.

라인내 품질관리의 정기점검방식에 관한 연구

서순근,김갑석,배봉수 동아대학교 공과대학부설 생산기술연구소 1996 生産技術硏究所硏究論文集 Vol.1 No.2

The assumptions of period checking policy for On-Line Quality Control presented by Taguchi are examined and his loss function and formulae are evaluated by simulation. New iterative procedures are proposed under Taguchi's loss and improved loss functions, respectively. Computational experiments are conducted for various combinations of parameter values and their results are discussed. Sensitivity analysis for assumption of random walk model is also illustrated with an example.

投資決定時 學習現象을 反映한 費用推定에 관한 硏究

徐洵根 동아대학교 공과대학 부설 한국자원개발연구소 1982 硏究報告 Vol.6 No.1

This paper deals with cost projections and net cash flow estimations adjusted for learning relating to financial plannings. A model is developed for investment decisions which incorporates a labor cost function to express the effects of employee learning during the start-up phase and is extended during the steady-state phase of production. The accounting treatment for a cost allocation based on the learning curve phenomenon is discussed and sensitivity analysis to asses the impacts of estimation errors in the learning rate and steady-state production time is explored. Finally an example to demonstrate the feasibility of proposed model and its methodology is illustrated.

분사처리 후 산부식 표면처리된 교정용 미니 임플랜트의 골유착능에 관한 연구

전미선,강윤구,모성서,이근혜,국윤아,김성훈 대한치과교정학회 2008 대한치과교정학회지 Vol.38 No.5

본 연구에서는 교정 치료 시 골내 고정원으로 사용되는 교정용 임플랜트의 표면처리 여부가 골유착능에 있어서 어떠한 효과를 보이는지 제거회전력의 측정을 통해 알아보고자 하였으며, 그에 따른 교정력 적용의 확장과 임상적 의의를 알아보고자 하였다. 실험군은 분사처리 후 산부식(Sand-blasted Large grit, and Acid etched, SLA) 표면 처리된 교정용 미니 임플랜트인 C-implant (Cimplant, Seoul, Korea)를 사용하였으며 대조군은 같은 디자인이지만 표면 처리를 하지 않은 평활면 C-implant를 사용하였다. 실험군과 대조군을 각각 2개씩 11마리의 가토 경골에 식립하였고 식립 후 6주에 가토를 희생시켜 제거회전력을 측정하여 t-test를 통하여 두 군의 제거회전력 차이의 통계적 유의성을 알아보았으며 조직표본을 만들어 조직소견을 관찰하였다. 실험결과 제거회전력은 SLA 처리한 C-implant 군이 평활면 C-implant 군보다 통계적으로 유의성 있게 높은 결과를 보였다 (p < 0.05). 평활면 C-implant 군의 평균 제거회전력 값은 4.614 Ncm이고, SLA C-implant 군의 평균 제거회전력 값은 6.286 Ncm로, SLA 군이 평활면 군보다 73% 더 높은 제거회전력에 대한 저항성을 나타내었다. 이상의 연구 결과에서 SLA 표면처리가 C-implant의 골유착능을 증가 시켰음을 알 수 있었다. 따라서 표면 처리된 교정용 미니 임플랜트는 기존의 임플랜트에 비해 좀 더 강한 힘에 저항할 수 있으며 탈락률을 낮출 수 있을 것으로 생각된다. Objective: The purpose of this study was to compare the torque resistance to removal of sandblasted large grit and acid etched (SLA) surface treated orthodontic mini-implants and smooth surface orthodontic mini-implants as well as performing histologic observations. Methods: Two groups of custom screw shaped orthodontic mini-implants (C-implant, 1.8 mm outer diameter × 9.5 mm length, Cimplant, Seoul, Korea) were designated. 22 SLA treated C-implants (SLA group) and 22 machined surface C-implants (machined group) were placed in the tibia metaphysis of 11 adult New Zealand white rabbits. Following a 6-week healing period, the rabbits were sacrificed. Subsequently, the C-implants were removed under reverse torque rotation with a digital torque measuring device and independent t-test was performed. Selected tissues were prepared for histologic observation. Results: The SLA group presented a higher mean removal torque value (6.286 Ncm) than the machined group (4.491 Ncm) which was statistically significant (p < 0.005). Histologic observation revealed a trend of more new bone formation in contact with the screw surface in the SLA group than the smooth group. Conclusions: The results of this study suggested that SLA surface treatment can enhance the osseintegration potential for C-orthodontic mini-implants.

시뮬레이션에 의한 投資分析

河正鎭,徐洵根,趙吉福 동아대학교 공과대학 부설 한국자원개발연구소 1987 硏究報告 Vol.11 No.1

In general, there are two methoes which investment proposals can be evaluated, one is deterministic approaches using single value or best estimates for the magnitude of returns and the other is pobabilistic approaches which involve probabilistically based analytical procedures and Monte Carlo simulation. The advantage of the method reflects much of reality more comprehensive than the former. This syudy estimates cumulative probabilistic distribution of internal rate of return and net present value using Monte Carlo simulation by combining variables; project cost, sales volume, unit sales price, operating cost and etc. The descriptive methods for discrete cash flows is proposed for use in economic risk analysis and numerically illustrated by microcomputer aided solution procedure. Further, to grasp the effect on the investment by variables, sensitivity analysis is carried out.

인플레이션率과 株式收益率 사이의 關係에 관한 實證的 硏究

河正鎭,徐洵根,金承卓 동아대학교 공과대학 부설 한국자원개발연구소 1987 硏究報告 Vol.11 No.1

The purpose of this study is to investigate empirically the relationship between inflation rate and stock market return in Korean stock market. After the literature was reviewed, two regression models were tested for two periods, 1976-1980 and 1981-1986. The results show that there exists strong negative relation between two variables in the higher inflation period, on the contrary unsignificant positive relation in the lower inflation period. The major feature of this study is the use of Box-Jenkins' ARIMA fitted values as measures of expected inflation rates. But this study has many limitations and weaknesses from the view of theory building and research methodology, thus some directions of study are suggested.

學習現象을 反映한 製品組合 模型에 관한 硏究

河正鎭,徐洵根 동아대학교 공과대학 부설 한국자원개발연구소 1984 硏究報告 Vol.8 No.1

In this paper, the realistic product-mix model reflecting learning curve phenomenon that attempts to determine the optimal allocation of scarce resources is formulated by broad discussion for its issues. The use of learning curve has been receiving increasing attention in recent years, but little research has been appeared in the incorporation of learning effects into resource allocation and aggregate planning. Because objective function and constraints are nonconvex and seperable, solution procedure by convex envelope approximation is developed and applied to a practical example.