• 한국수자원학회:학술대회논문집
• /
• 한국수자원학회 2004년도 학술발표회
• /
• pp.595-598
• /
• 2004

This research seeks to derive the design rainfalls through the L-moment with the test of homogeneity, independence and outlier of data on annual maximum daily rainfall at 38 rainfall stations in Korea. To select the appropriate distribution of annual maximum daily rainfall data by the rainfall stations, Generalized Extreme Value (GEV), Generalized Logistic (GLO), Generalized Pareto (GPA), Generalized Normal (GNO) and Pearson Type 3 (PT3) probability distributions were applied and their aptness were judged using an L-moment ratio diagram and the Kolmogorov-Smirnov (K-S) test. Parameters of appropriate distributions were estimated from the observed and simulated annual maximum daily rainfall using Monte Carlo techniques. Design rainfalls were finally derived by GEV distribution, which was proved to be more appropriate than the other distributions.

• 한국농공학회논문집
• /
• 제46권3호
• /
• pp.31-42
• /
• 2004

This research seeks to derive the design rainfalls through the L-moment with the test of homogeneity, independence and outlier of data on annual maximum daily rainfall at 38 rainfall stations in Korea. To select the appropriate distribution of annual maximum daily rainfall data by the rainfall stations, Generalized Extreme Value (GEV), Generalized Logistic (GLO), Generalized Pareto (GPA), Generalized Normal (GNO) and Pearson Type 3 (PT3) probability distributions were applied and their aptness were judged using an L-moment ratio diagram and the Kolmogorov-Smirnov (K-S) test. Parameters of appropriate distributions were estimated from the observed and simulated annual maximum daily rainfall using Monte Carlo techniques. Design rainfalls were finally derived by GEV distribution, which was proved to be more appropriate than the other distributions.

• 기술혁신학회지
• /
• 제17권4호
• /
• pp.733-762
• /
• 2014

정부는 과학기술 핵심 인프라인 연구시설 장비의 이용 효율화를 위해 국가 연구개발 사업예산을 통해 구축한 연구시설 장비를 국가과학기술정보서비스(NTIS)에 등록할 것을 의무화하고 있다. 본 연구는 국가연구시설 장비의 효율적 관리를 위한 연구기관 구성원의 인식도 조사를 시행하고, 식스시그마 DAMIC 방법론을 통해 국가연구시설 장비 등록 프로세스 개선에 영향을 미치는 주요 요인을 도출함으로써 국가연구시설 장비의 운영 선진화와 활용 극대화 정책에 기여하고자 하였다. 이를 위하여 A대학교 사례를 중심으로 먼저 연구시설 장비의 대학 관계자인 연구책임자, 보직교수, 대학원생, 연구원, 직원을 대상으로 설문과 인터뷰를 수행하였다. 인식도 조사 결과, 연구시설 장비의 전주기적 관리와 구체적인 절차에 대한 인식이 부족함을 확인할 수 있었다. 대학의 경우 국가연구시설 장비의 운영선진화와 활용극대화를 위해서는 대학현장의 의견을 수렴하고 대학의 고유한 특성을 반영한 정책 추진이 필요함을 알 수 있었다. 연구시설 장비 등록 프로세스 개선을 위해 식스시그마 방법을 통해 CTQ-Y로 연구시설 장비 등록기한 준수율과 연구시설 장비 등록정확도를 선정하였다. Process Map과 C&E Diagram을 통해 72개 잠재원인변수를 도출하였고, 이를 대상으로 X-Y Matrix와 Pareto Chart를 통해 최종적으로 13개 잠재원인변수를 확정하였으며 개선안의 방향을 제시하였다. 연구기관마다 연구기관의 특성에 맞게 등록프로세스 개선에 영향을 미치는 잠재원인변수를 추출하고 이를 개선하기 위한 상세개선안을 마련함으로써 국가연구시설 장비의 활용 극대화를 제고할 수 있을 것이다.

• Advances in aircraft and spacecraft science
• /
• 제4권6호
• /
• pp.701-709
• /
• 2017

One of the components that used in the satellite thermal control subsystem is the Mechanically Pumped Fluid Loop (MPFL) system; this system mostly used in geosynchronous orbit (GEO) satellites, and can transfer heat from a hot point to a cold point using the fluid which circulated in a closed loop. Heat radiates to the deep space at the cold plate to cool down the fluid temperature. In this research, the radiative heatexchanger (RHX) for a MPFL system is optimized. The genetic algorithm has been used for minimizing the total mass and pressure drop by considering a constant transferred heat rate at the heat exchanger. The optimization has been done in two cases. In case I, two parameters are considered as a goal function, so optimization is performed using NSGA-II method. Results of optimization are shown in the pareto diagram. In case II, the diameter of pipe is considered constant, so the optimized value for distances of the parallel pipes is obtained by using the genetic algorithm, in which the system has the least total mass. Results show that in the RHX, by increasing the pipe diameter, pressure drop decreases and total mass increases. Also by considering a constant value for pipe diameter, an optimum distance between pipes and pipe length are obtained in which the system has a minimum mass.

• Journal of Computational Design and Engineering
• /
• 제1권4호
• /
• pp.256-265
• /
• 2014

Energy efficiency is an essential consideration in sustainable manufacturing. This study presents the car fender-based injection molding process optimization that aims to resolve the trade-off between energy consumption and product quality at the same time in which process parameters are optimized variables. The process is specially optimized by applying response surface methodology and using non-dominated sorting genetic algorithm II (NSGA II) in order to resolve multi-object optimization problems. To reduce computational cost and time in the problem-solving procedure, the combination of CAE-integration tools is employed. Based on the Pareto diagram, an appropriate solution is derived out to obtain optimal parameters. The optimization results show that the proposed approach can help effectively engineers in identifying optimal process parameters and achieving competitive advantages of energy consumption and product quality. In addition, the engineering analysis that can be employed to conduct holistic optimization of the injection molding process in order to increase energy efficiency and product quality was also mentioned in this paper.

• 품질경영학회지
• /
• 제38권3호
• /
• pp.340-353
• /
• 2010

Properly designed and well-executed services enable e-commerce companies to capture the unique needs and preferences of customers, help them build customer loyalty, and thereby, strengthen their competitiveness in the marketplace. An object of this study is the new open-market company and it has only 3 percent of the market share. Therefore, it is needed to raise the market share by improving the service qualities. This article presents a six sigma project for service quality improvement in the open-market company. This study was carried out based on five steps of DMAIC which is six sigma technique. First, a defect rate was defined as unsatisfaction rate. In addition, 50-people data was analyzed and it was shown that the defect level was 2.5 sigma level. In this study, in order to raise the sigma level, novel eight action items were determined based on SIPOC, FDPM, cause and effect diagram, matrix chart, Pareto chart and statistical analysis.

• 한국농공학회:학술대회논문집
• /
• 한국농공학회 2005년도 학술발표논문집
• /
• pp.284-287
• /
• 2005

The objective of this study is to check into variation trends of design rainfall according to change of the number of years for observed data. To make comparative study of the relation between design rainfall and recorded year, this study was used maximum rainfall for 24-hr consecutive duration at Gangneung, Seoul, Incheon, Chupungnyeong, Pohang, Daegu, Jeonju, Ulsan, Gwangju, Busan, Mokpo and Yeosu rainfall stations. The tests for Independence, Homogeneity and detection of outliers were used Wald-Wolfowitz's test, Mann-Whitney's test and Grubbs and Beck test respectively. To select appopriate distribution, the distribution of genaralized pareto(GPA), generalized extreme value(GEV), generalized logistic(GLO), lognormal and pearson type 3 distribution is judged by L-moment ratio diagram and Kolmogorov-Smirnov (K-S) test. Design rainfall was estimated by at-site frequency analysis using L-moments and Generalized extreme value(GEV) distribution according to change of the number of years for observed data. Through the comparative analysis for design rainfall induced by L-moments and GEV distribution, relationship between design rainfall and recorded year is provided.

• Industrial Engineering and Management Systems
• /
• 제9권3호
• /
• pp.251-261
• /
• 2010

This article demonstrated the application of the Fuzzy Data Envelopment Analytical Hierarchy Process (FDEAHP) to evaluate the root causes of critical defect problems occurring in the production of liquid medicine. The methodology of the research began by collecting the defect data by using Check Sheets, and ranking the significant problems by using a Pareto Diagram. Two types of major problems were found to occur, including glass fragments in the medicine and damaged lid threads. The causes of each problem were then analyzed by using Cause and Effect Diagrams. The significant causes were ranked by FDEAHP under three criteria, Severity (S), Occurrence (O) and Detection (D), followed by the framework of the FMEA Technique. Two causes with the highest Final Weight (FW) of each problem were selected to be improved, such as installing auxiliary equipment, using the Poka-Yoke system, setting the scale of the shaft and lathing the bushes of each bottle size. The results demonstrated a reduction in defects from 3.209% to 1.669% and showed that improving a few significant root causes, identified by an experienced decision maker, was sufficient to reduce the defect rate.

• 정보관리학회지
• /
• 제30권1호
• /
• pp.111-129
• /
• 2013

본 연구는 6시그마 DMAIC 방법론의 정의(Define)와 측정(Measure) 단계의 기법들을 활용하여 대학도서관 멀티미디어 서비스 개선에 영향을 미치는 주요 변수들을 도출하였다. 이를 위하여 S대학교 중앙학술정보관의 사례를 중심으로 현장 사서들의 브레인스토밍, X-Y Matrix와 특성요인도 작성, 도서관 홈페이지를 통한 이용자 의견 분석, 이용자 인터뷰 등을 통하여 대학도서관 멀티미디어 서비스의 프로세스를 분석하고, 핵심 품질특성을 지표화하였다. 그리고 Process Map과 특성요인도를 통하여 멀티미디어 서비스에 영향을 미치는 잠재원인변수들을 도출하고, 도출한 잠재원인변수를 X-Y Matrix와 Pareto Chart에 의하여 우선순위화하여 멀티미디어 서비스에 영향을 미치는 주요 요인으로 '자료 선정 전담자 유무', '자료 선정주기', '독립된 멀티미디어실 운영 유무', '자료 배가 방법', '인기자료 안내 여부', '입수자료 통보 여부', '신간 자료 안내 방법', '구입주문처리 방법', '주문자료 진행사항 점검 주기', '자료 신청자 유형', '자료 신청 방법', '반납 시 자료 상태 점검 여부', '소장자료 목록 안내 방법', '연체자료 회수방법'의 14개 변수를 도출하였다.

• 한국산학기술학회논문지
• /
• 제10권5호
• /
• pp.1009-1019
• /
• 2009

본 연구에서는 우리나라 수위관측소들 중에서 관측 유량이 검증된 총 19개 유역을 선정하고 관측된 홍수량을 사용하여 적정 설계홍수량을 유도함으로써 우리나라의 설계홍수량 특성을 분석하였다. 대상유역별로 관측개시 년도에서부터 분석 시작년을 기준으로 1년씩 증가 시키는 점진적 구성 방식으로 연최대홍수량에 대한 빈도분석을 실시하기 위해, 변동특성을 이동평균법에 의해 분석하였다. 19개 대상유역에 대한 연최대홍수량 계열 구성기간별로 기본통치를 산정하고 독립성, 동질성 및 Outiler 검정을 실시하였다. Gumbel, Generalized Extreme Value, Generalized Logistic 및 Generalized Pareto 분포의 적합도 검정을 LH-모멘트비도와 Kolmogorov-Smirnov 검정에 의해 수행하였다. 적정 확률분포로 선정된 GEV 분포의 매개변수를 확률가중모멘트의 치수 변화에 의한 L, L1, L2, L3 및 L4-모멘트법에 의해 추정하고 대상유역 및 연최대홍수량 계열 구성 기간별 설계홍수량을 유도하였다. 본 연구에서 사용한 변동률 분석에 따라 최근 지구온난화에 따른 우리나라 기후 변화를 고려한 적절한 수리구조물의 설계 조건변경시기는 2002년 전후로 하여야 할 것이다.