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공학 Reading & Writing 교재 개발 및 학습성과 분석
정호연(Hoyeon Chung),전오성(Oh Sung Jun),유규선(Kyusun Yoo),장미영(Mi Young Jang) 한국공학교육학회 2011 공학교육연구 Vol.14 No.6
The authors have developed a reading & writing textbook for engineering students to improve their communication capability, and also analyzed the outcomes that the students accomplished through the Engineering Reading and Writing class. The reading & writing textbook has been organized to be used as a guidebook with which the engineering students can practically solve the problems that they would face continuously after they finish their regular curriculum and when they are employed. The questionnaire survey analysis has been performed in order to evaluate the textbook contents, lecturing, and learning outcomes for the lecturers and students finished the engineering reading and writing classes. Desirable evaluation has been resulted in the broad areas: subject extraction from the readings, logical understanding, summarizing, practical writing, writing principle, etc.
쇽옵서버 피스톤로드 제조공정에 대한 공정관리 시스템 개발
정호연(Hoyeon Chung),신동주(Dong Joo Shin) 한국산업경영시스템학회 2009 한국산업경영시스템학회지 Vol.32 No.4
쇽옵서버 피스톤로드(shock absorber piston rod)는 자동차의 충격과 진동의 흡수에 작용하는 자동차 현가장치(sus-pension equipment)부품의 일종이다. 피스톤로드는 자동차 충격흡수에 매우 밀접한 영향을 주기 때문에 제조에 있어서 고도의 정밀도와 표면 매끄러움이 요구된다. 피스톤로드의 제조공정은 선삭, 홈가공, 밀링, 건조 등 여러 공정으로 구성되는데, 여기서 품질불량에 가장 크게 영향을 주는 공정은 선삭공정(lathing process)이다. 이는 선삭공정의 가공공구(insert component)가 주원인으로서 반복되는 가공으로 인한 공구의 마모(abrasion)나 파손(breakage)이 주요 원인으로 지적되고 있다. 따라서 가공 데이터를 수집 분석하여 공구의 교체 시기를 파악한다거나 가공 부품의 측정 데이터가 관리도 상하한선 내에 있는지 등 가공 공정 전반에 대한 체계적인 공정관리 시스템 개발이 요구된다. 본 연구에서는 자동차 쇽업서버 피스톤로드 제조공정의 가공 정보를 체계적으로 수집하여 관리하고 분석하는 자동차 쇽업서버 피스톤로드 제조공정에 대한 공정관리시스템을 개발하는 것이 목적이다. 개발결과 피스톤 로드의 측정 치수 변화 및 불량발생을 측정, 감지할 수 있었으며, 본 시스템을 통해 가공공구의 치수오차를 보정(compensation)하고 공정의 불량발생을 조기에 방지 함으로써 불량률은 1/5로 정감하고 작업자 수도 1/2로 감소시킬 수 있었다.
정호연(Hoyeon Chung) 한국산업경영시스템학회 2021 한국산업경영시스템학회지 Vol.44 No.2
The purpose of this study is to analyze the adequacy of production capacity of the assembly process system of mobile bath vehicle’s top box panel and process design through a simulation analysis. Towards this end, the layout of the facility designed with pre-verification job using a simulation modeling and an experiment, and facility, logistics process, and personnel input method were made into a simulation model, and the design system’s adequacy was evaluated through an experiment. To produce 120 mobile bath vehicles annually, it was analyzed that 14 general workers and seven skilled workers were adequate through the experiment. It was also identified that three painting process lines carried out through outsourcing were adequate. Production lead time was 201.7 hours on average and it was 230 hours maximum. To meet customer delivery service level of 95% within the deadline when establishing a customer order and vehicle delivery plan, it was analyzed that more than 215 hours of lead time is needed minimum. If the process cycle time is reduced to 85% upon system stabilization and skillfulness improvement, it was analyzed that annual output of 147 vehicles can be achieved without additional production line expansion.
정호연,안재근,박순달 한국경영과학회 2000 韓國經營科學會誌 Vol.25 No.2
The most vital arc in the maximum flow problem is that arc whose removal results in the greatest reduction in the value of the maximal flow between a source node and a sink node. This paper develops an algorithm to determine such a most vital arc in the maximum flow problem. We first define the transformed network corresponding to a given network in order to compute the minimal capacity for each candidate arc. The set of candidate arcs for single most vital arc consists of the arcs whose flow is at lest as great as the flow over every arc in a minimal cut. As a result we present a method in which the most vital arc is determined more easily by computing the minimal capacity in the transformed network. The proposed method is demonstrated by numerical example and computational experiment.
정호연,박순달 한국경영과학회 1995 韓國經營科學會誌 Vol.20 No.1
The purpose of this paper is to develop a method of the sensitivity analysis that can be applied to a non-tree solution of the minimum cost flow problem. First, we introduce two types of sensitivity analysis. A sensitivity analysis of Type 1 is the well known method applicable to a tree solution. However this method can not be applied to a non-tree solution. So we propose a sensitivity analysis of Type 2 that keeps solutions of upper bounds at upper bounds, those of lower bounds at lower bounds, and those of intermediate values at intermediate values. For the cost coefficient we present a method that the sensitivity analysis of Type 2 is solved by finding the shortest path. Besides we also show that the results of Type 2 and Type 1 are the same in a spanning tree solution. For the right-hand side constant or the capacity, the sensitivity analysis of Type 2 is solved by a simple calculation using arcs with intermediate values.