• Proceedings of the Korea Water Resources Association Conference
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• 2009.05a
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• pp.89-93
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• 2009

홍수기에 집중되는 하천유출량을 갈수기에 적절히 활용하기 위한 대표적인 시설이 댐이다. 제한된 용수공급량을 적절히 분배해 용수수요량을 만족시키면서 미래 갈수기시 용수공급을 위한 댐 저류량을 조절하는 것이 댐 운영의 중요한 목적 중 하나이다. 본 연구에서는 댐 저류량에 따라 댐 계획방류량을 일정비율 줄여주는 Hedging Rule을 5단계로 적용하여 댐의 상시만수위 저류량에 대한 실제 저류량의 편차 절대치 합, 수요에 대한 용수공급 부족량의 합, 그리고 하천유지유량에 대한 하천유량 부족량의 합을 목적함수로 하여 혼합정수 선형계획법(MILP, Mixed Integer Linear Programming)으로 식을 구성하였다. 한강수계의 다목적댐인 충주, 횡성, 소양강 댐과 용수전용댐인 광동 댐, 그리고 발전용 댐이지만 비교적 큰 저류용량을 가진 화천 댐을 댐 연계 운영 대상으로 하여 수자원장기종합계획의 2003년 유출량 및 수요량 자료와 댐운영실무편람의 댐 계획방류량 자료를 10일 단위로 입력하여 GAMS/CPLEX를 이용해 최적화하였다. 그 결과 생공용수 수요량 99.99%, 농업용수 수요량 99.91%, 그리고 하천유지용수 수요량 99.24%를 충족시키면서, 댐 저류율이 66.54%에서 86.39%로 증가하였다.

• Proceedings of the Korea Water Resources Association Conference
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• 2010.05a
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• pp.832-836
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• 2010

물 부족에 대비한 대체수자원 개발과 함께 최근 들어 환경성과 생태계를 고려한 녹색도시 조성이 부각되면서 빗물이용을 통한 용수확보가 지속적으로 추진되고 있다. 녹색도시 조성은 조경시설 및 수경시설에서의 용수 사용량을 증가시키므로 용수확보에 대한 부담을 경감시키고 대상 사업의 환경성을 강조하기 위한 것으로 판단된다. 그러나 최근의 빗물이용시설의 도입 현황을 살펴보면 설계 시 집수면적이나 대지면적의 일정비율 이상을 설치하는 간편식이 주로 이용하고 있다. 간편식을 이용한 방법은 집수면의 토지이용 특성, 물 사용량을 고려할 수 없기 때문에 시설이 설치된 후 운영효율 저하가 우려된다. 본 연구에서는 간편식 법의 문제점 개선과 함께 시설 설계 시 편리하게 활용할 수 있도록 엑셀기반의 저류용량 계획선도를 개발하였다. 본 계획선도는 대상지역의 강우량과 토지이용 특성을 입력한 후 용수 공급 패턴(매일 일정량 활용, 무강우 시 일정량 활용, 하절기에 중점적으로 활용)에 따라 빗물이용시설 용량을 결정할 수 있다. 인터넷을 통해 기상청 등의 강우자료 서비스가 진행 중이므로 공간적인 제약 없이 전국적으로 활용도가 높을 것으로 기대된다.

• Korean Management Science Review
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• v.30 no.2
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• pp.133-141
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• 2013

In this paper, we considers the outsourcing decision problem in a single machine scheduling problem. The decision problem is to determine for each job whether to be processed on an in-house manufacturing or external facilities(outsourcing). Moreover, this paper considers a situation where each job has a due date. The objective of the problem is to minimize the outsourcing cost, subject to the due date constraints. The considered problem is proved to be NP-hard. Some solution properties and valid inequalities are derived, and an effective lower bound is derived based on the LP-relaxation. The results of experimental tests are presented to evaluate the performance of the suggested lower bound.

• The Journal of the Korea institute of electronic communication sciences
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• v.11 no.1
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• pp.107-112
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• 2016

Fastener is a very important component that is used in various areas in industry. Recently, various color fasteners are introduced. According to this, online inspection is required in this area. In this paper, an algorithm for the automatic extraction of the surface of color fastener using color information and dynamic programming is presented. The outer boundary of fastener is found using the difference of color that enables robust processing. The inner boundary of fastener is found by dynamic programming that uses the difference of brightness value within fixed area after converting image to polar coordinate. Experiments are done using the same parameters.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.49 no.5
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• pp.365-372
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• 2021

This paper deals with an optimal Weapon-Target Assignment (WTA) algorithm for Closed-In Weapon Systems (CIWS), considering variable burst time. In this study, the WTA problem for CIWS is formulated based on Mixed Integer Linear Programming (MILP). Unlike the previous study assuming that the burst time is fixed regardless of the engagement range, the proposed method utilizes the variable burst time based on the kill probability according to the engagement range. Thus, the proposed method can reflect a more realistic engagement situation and reduce the reaction time of CIWS against targets, compared to the existing method. In this paper, we first reformulate the existing MILP-based WTA problem to accommodate the variable burst Time. The proposed method is then validated through numerical simulations with the help of a commercial optimization tool.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.41 no.7
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• pp.645-653
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• 2017

In bone tissue engineering, polycaprolactone (PCL) is one of the most widely used biomaterials in the manufacturing of scaffolds as a synthetic polymer having biodegradability and biocompatibility. The strut width in the fabrication of scaffolds is an important part of tissue regeneration in in-vitro and in-vivo experiments, because it affects not only the pore size but also the porosity. In this study, we used polymer deposition system (PDS) and design of experiments (DOE) to explore the optimal process conditions to achieve a systematic and efficient scaffold manufacturing process, using temperature, pressure, scan velocity, and nozzle tip height as the parameters for the experiments. The aim of this research was to fabricate a 3D PCL scaffold having a uniform strut width of $150{\mu}m$ using DOE; it was proved that the strut width was constant in all the experimental groups by fabricating the PCL scaffolds according to various pore patterns as well as one pore pattern.

• The Korean Journal of Applied Statistics
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• v.35 no.2
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• pp.229-250
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• 2022

Since the publication of Markowitz's (1952) mean-variance portfolio model, research on portfolio optimization has been conducted in many fields. The existing mean-variance portfolio model forms a nonlinear convex problem. Applying Dantzig's linear programming method, it was converted to a linear form, which can effectively reduce the algorithm computation time. In this paper, we proposed a Dantzig perturbation portfolio model that can reduce management costs and transaction costs by constructing a portfolio with stable and small (sparse) assets. The average return and risk were adjusted according to the purpose by applying a perturbation method in which a certain part is invested in the existing benchmark and the rest is invested in the assets proposed as a portfolio optimization model. For a covariance estimation, we proposed a Gaussian kernel weight covariance that considers time-dependent weights by reflecting time-series data characteristics. The performance of the proposed model was evaluated by comparing it with the benchmark portfolio with 5 real data sets. Empirical results show that the proposed portfolios provide higher expected returns or lower risks than the benchmark. Further, sparse and stable asset selection was obtained in the proposed portfolios.

• Proceedings of the Safety Management and Science Conference
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• 2010.11a
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• pp.639-649
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• 2010

신뢰성 기술은 제품이 고장 없이 일정기간 사용할 수 있게 하는 기술로 시장점유율과 고객만족을 높이는 효과적이고 전략적인 필수 요소이다. 검사시점의 적합성에 대한 평가가 아닌 제품 및 시스템의 설계에서부터 폐기까지의 제품수명주기에 대한 신뢰성 평가를 다루는 제품의 신뢰성인증과 신뢰성경영시스템 인증 확보가 시급한 과제이다. 이를 위한 제품 수명의 평균과 분산을 효과적으로 관리할 수 있는 신뢰성 식스시그마 기술개발과 확보가 중요 현안과제이다. 정규분포를 가정한 대부분의 품질경영시스템에서의 식스시그마 접근법은 비정규 분포를 따르는 신뢰성특성과 실험계획기법 등을 고려해야 하는 신뢰성 식스시그마에서의 적용의 한계가 많다. 본 연구에서는 품질혁신 방법론인 식스시그마 기법을 토대로 신뢰성경영시스템에서 맞는 식스시그마 구축의 방향성을 제시하고자 한다.

• Journal of the Korean Association of Geographic Information Studies
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• v.7 no.2
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• pp.16-28
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• 2004

A seam-line determination algorithm is proposed to determine image border-line in mosaicing using the transformation of gray value differences and dynamic programming. Since visually good border-line is the one along which pixel differences are as small as possible, it can be determined in association with an optimal path finding algorithm. A well-known effective optimal path finding algorithm is the Dynamic Programming (DP). Direct application of the dynamic programming to the seam-line determination causes the distance effect, in which seam-line is affected by its length as well as the gray value difference. In this paper, an adaptive cost transform algorithm with which the distance effect is suppressed is proposed in order to utilize the dynamic programming on the transformed pixel difference space. Also, a figure of merit which is the summation of fixed number of the biggest pixel difference on the seam-line (SFBPD) is suggested as an evaluation measure of seamlines. The performance of the proposed algorithm has been tested in both quantitively and visually on various kinds of images.

• Journal of the Society of Disaster Information
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• v.14 no.2
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• pp.219-229
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• 2018

Purpose: This research proposes an optimization model for effective evacuation routing and scheduling of civilians near the border area when full-scale war threats heighten. Method: To reflect the reality, administrative unit network is created using Kruscal's Algorithm, Harmony Search, CCRP based on the geographical features, population, and traffic data of real cities, and then, optimal civilian evacuation routes are found. Results: Optimal evacuation routes and schedules are computed by repetitive experiments, and it is found that the scenario that minimizes the average civilian evacuation time is effective for the civilian evacuation plan. Conclusion: By using the civilian evacuation plan this research proposes, at the time of establishing the actual civilian evacuation plan, quantitative analysis is used for the effective plan making rather than only depending.