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단일 호이스트 생산시스템에서 다양한 주문을 처리하기 위한 분지한계 기반의 휴리스틱 일정계획
이정구(Jungkoo Lee),김정배(Jeongbae Kim),고시근(Shiegheun Koh) 대한산업공학회 2016 대한산업공학회지 Vol.42 No.3
This paper deals with the single-hoist and multiple-products scheduling problem. Although a mixed integer linear programming model for the problem was developed earlier, a branch-and-bound based heuristic algorithm is proposed in this paper to solve the big-size problems in real situation. The algorithm is capable of handling problems incorporating different product types, jobs in the process, and tank capacities. Using a small example problem the procedure of the heuristic algorithm is explained. To assess the performance of the heuristic we generate a bigger example problem and compare the results of the algorithm proposed in this paper with the optimal solutions derived from the mathematical model of earlier research. The comparison shows that the heuristic has very good performance and the computation time is sufficiently short to use the algorithm in real situation.
요소수의 분무 특성과 관내 분무 거동에 관한 실험적 연구
이정구 ( Jungkoo Lee ),이창기 ( Changki Lee ),우승철 ( Seungchul Woo ),백승주 ( Seungju Beak ),이수홍 ( Soohong Lee ),박성훈 ( Sunghoon Park ),이기형 ( Kihyung Lee ) 한국액체미립화학회 2018 한국액체미립화학회 학술강연회 논문집 Vol.2018 No.-
As a method of reducing NOx in a diesel vehicle, lean NOx trap (LNT) and selective catalytic reduction (SCR) are mainly used. The Urea-SCR system has been evaluated as the best method of reducing NOx. In the Urea-SCR system, the urea water solution is injected at the upstream of the SCR catalyst. At this time, the urea water solution is hydrolyzed and decomposed into ammonia gas. The ammonia gas reacts with NOx in the SCR catalyst and NOx is converted to water and nitrogen. In order to improve the reduction efficiency, the SCR system should be optimized so that the urea water solution is completely converted to ammonia gas and has a high uniformity distribution. In this study, spray characteristics of urea water solution were analyzed through visualization using high speed camera under various test conditions. In addition, urea water solution was sprayed into a transparent exhaust pipe made with Pyrex tube to analyze spray behavior and wall-wetting phenomenon. In order to observe the influence of the exhaust pipe and the mixer shape, three types of transparent exhaust pipes and two types of SCR mixers were used.
Micro-Channel의 수치해석 및 제작을 통해 Micro PEM Fuel Cell의 성능 평가
이정구(Jungkoo Lee),박성호(Seongho Park),최갑승(Kap-Seung Choi),김형만(Hyung-Man Kim) 한국자동차공학회 2013 한국자동차공학회 지부 학술대회 논문집 Vol.2013 No.11
A fuel cell is most interesting new power source because it solves not only the environment problem but also natural resource exhaustion problem. In this paper, hydrogen gas flow in micro-channel was numerically analyzed about various channel shapes to improve the efficiency of micro fuel cell. Flow characteristics with the same boundary condition were simulated in six different shapes of micro-channels which have been already developed and newly designed as well. The result of analysis shows that characteristics of flow such as velocity, uniformity, and flow rate, depend highly upon the channel shape itself. That means it is expectable to increase the efficiency of micro fuel cell through optimal configuration of channel shape for hydrogen gas flow. Finally, actual micro flow channels were fabricated using SU-8 and the performance of PEM fuel cell was also carried out with these micro prototypes.