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LNG Tank Cooling Down 시스템 모델링 및 내부 거동 분석
신경석,황성원 한국공업화학회 2020 한국공업화학회 연구논문 초록집 Vol.2020 No.-
상온의 탱크에 극저온의 LNG가 바로 선적되면 온도 상승에 따른 다량의 Boil-Off gas(BOG)가 발생하여 상당한 압력 변화를 야기하고, 탱크 재질이 열 응력 유발로 인해 파괴될 수 있다. 따라서, 동적 모사를 통해 탱크 내부의 압력 및 온도 변화를 예측할 필요가 있다. 본 연구에서는 MATLAB을 이용하여 LNG spray 을 통해 tank내 온도를 낮추는 예냉과정(cool down)을 모델링하고, 그에 따라 동적 모사를 진행하였다. 이를 통해 시간에 따른 tank 내부의 압력 및 온도 변화를 예측하였다. 또한, 이를 기반으로 cool down시 탱크 내부에 축적되지 않고 방출되는 BOG의 양과 요구되는 LNG 분사량 계산의 정확도를 높혔다
신경석,김여근 한국경영과학회 2007 韓國經營科學會誌 Vol.32 No.1
In this paper, we present a symbiotic evolutionary algorithm for multi-objective optimization. The goal in multi-objective evolutionary algorithms (MOEAs) is to find a set of well-distributed solutions close to the true Pareto optimal solutions. Most of the existing MOEAs operate one population that consists of individuals representing the entire solution to the problem. The proposed algorithm has a two-leveled structure. The structure is intended to improve the capability of searching diverse and good solutions. At the lower level there exist several populations, each of which represents a partial solution to the entire problem, and at the upper level there is one population whose individuals represent the entire solutions to the problem. The parallel search with partial solutions at the lower level and the integrated search with entire solutions at the upper level are carried out simultaneously. The performance of the proposed algorithm is compared with those of the existing algorithms in terms of convergence and diversity. The optimization problems with continuous variables and discrete variables are used as test-bed problems. The experimental results confirm the effectiveness of the proposed algorithm.
공생 진화알고리듬을 이용한 확장된 hub-and-spoke수송네트워크 설계
신경석,김여근 한국경영과학회 2006 한국경영과학회지 Vol.31 No.2
In this paper, we address an extended hub-and-spoke transportation network design problem (EHSNP). In the existing hub location problems, the location and number of spokes, and shipments on spokes are given as input data. These may, however, be viewed as the variables according to the areas which they cover. Also, the vehicle routing in each spoke needs to be considered to estimate the network cost more correctly. The EHSNP is a problem of finding the location of hubs and spokes, and pickup/delivery routes from each spoke, while minimizing the total related transportation cost in the network. The EHSNP is an integrated problem that consists of several interrelated sub-problems. To solve EHSNP, we present an approach based on a symbiotic evolutionary algorithm (symbiotic EA), which are known as an efficient tool to solve complex integrated optimization problems. First, we propose a framework of symbiotic EA for EHSNP and its genetic elements suitable for each sub-problem. To analyze the proposed algorithm, the extensive experiments are performed with various test-bed problems. The results show that the proposed algorithm is promising in solving the EHSNP.