• 한국산학기술학회논문지
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• 제7권1호
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• pp.89-95
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• 2006

공급사슬망에서 분산되어있는 제조시스템에 대한 생산 계획수립은 공급사슬관리의 주요 연구분야 중의 하나이다. 본 논문은 공급사슬망에서 자원제약을 갖는 다단계 다품목 로트사이즈 결정 문제(Multi-Level, multi-item Capacitated Lot Sizing Problem: MLCLSP)를 위한 알고리즘을 제시한다. MLCLSP는 MIP(mixed integer program) 문제에 해당한다. 제안된 알고리즘은 휴리스틱과 최적화 패키지인 LINGO를 이용해 서로 반복적인 방식으로 해를 풀어나가는 혼성적인 성격을 갖는다. 휴리스틱을 이용하여 정수형 변수를 결정한 후, 얻게 되는 LP(linear program) 문제를 LINGO를 이용하여 해를 개선해 나가는 방식을 기본으로 한다. 본 논문에서는 탐색 휴리스틱 기법으로 임의 재시작 타부탐색 알고리즘을 제시한다. 다양한 시나리오의 실험을 통해 제안된 알고리즘들의 성능을 평가한다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 춘계학술대회 논문집
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• pp.833-835
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• 2002

In this paper, we propose multi-resolutional representation of B-rep solid models using the selective Boolean operations on non-manifold geometric models. Since the union and subtraction operations of the selective Boolean operations are commutative, the integrity of the model is guaranteed for reordering design features. A multi-resolution representation is established using a non-manifold merged set model and a feature modeling tree reordered according to some criterion of level of detail (LOD). Then, a solid model for a specified LOD can be extracted from this multi-resolution model using the selective Boolean operations.

• 국제학술발표논문집
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• The 2th International Conference on Construction Engineering and Project Management
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• pp.509-519
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• 2007

Private financing is playing an increasing role in public infrastructure construction projects worldwide. However, private investors/operators are exposed to the financial risk of low profitability due to the inaccurate estimation of facility demand, operation income, maintenance costs, etc. From the operator's perspective, a sound and thorough financial feasibility study is required to establish the appropriate capital structure of a project. Operators tend to reduce the equity amount to minimize the level of risk exposure, while creditors persist to raise it, in an attempt to secure a sufficient level of financial involvement from the operators. Therefore, it is important for creditors and operators to reach an agreement for a balanced capital structure that synthetically considers both profitability and repayment capacity. This paper presents an optimal capital structure model for successful private infrastructure investment. This model finds the optimized point where the profitability is balanced with the repayment capacity, with the use of the concept of utility function and multi-objective GA (Generic Algorithm)-based optimization. A case study is presented to show the validity of the model and its verification. The research conclusions provide a proper capital structure for privately-financed infrastructure projects through a proposed multi-objective model.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2001년도 봄 학술발표회 논문집
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• pp.827-832
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• 2001

A multi-level optimum design algorithm for prestressed concrete (PSC) box girders is proposed in this paper. To save the numerical efforts, a multi-level optimization technique using model coordination method that separately utilizes both tendon profile design and section design is incorporated. And also, a reduced basis technique for the efficient tendon profile optimization is proposed in this paper. From the numerical investigations, it may be positively stated that the optimum design of PSC box girder based on the new approach proposed in this study will lead to more rational and economical design compared with the currently available designs.

• 농촌계획
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• 제11권1호
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• pp.9-15
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• 2005

Preservation of geometrical context of terrains in a digitized format is useful in handling and making modification to the data. Digitization of three-dimensional terrain still proves a great challenge due to heavy load of context required to retain details of topological and geometrical information. Methods of simplification, restoration and multi-level terrain generation are often employed to transform the original data into a compressed digital format. However, reduction of the stored data size comes at an expense of loss of details in the original data set. This article reports on an alternative scheme for simplification and restoration of terrain data. The algorithm utilizes the fact that the terrain formation and patterns can be predicted and modeled through the fractal algorithm. This method was used to generate multi-level terrain model based on NGIS digital maps with preserving geometrical context of terrains.

• 한국항행학회논문지
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• 제22권2호
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• pp.133-140
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• 2018

최근 항공전자시스템 개발에서 비용절감 및 안전인증을 지원하는 방법의 하나로 모델 기반 설계 기법을 사용한다. 모델 기반 설계를 이용하여 항공기 및 항공전자 장비 (아이템)의 성능 분석 및 안전성 분석을 지원하기 위하여 이종의 시뮬레이터를 연동하는 멀티 도메인 시뮬레이션 환경을 개발하였다. 대기 자료 컴퓨터와 통합 다기능 프로브를 항공기 수준에서 검증 할 수 있는 멀티 도메인 시뮬레이션 환경을 제시한다. 모델은 Simulink로 개발하였고, 항공기 수준에서 모델을 검증하기 위해서 비행시뮬레이터인 X-Plane 10을 사용하였다. 항공전자 시스템 모델기능을 항공기 수준에서 시험하였고, 모델과 비행시뮬레이터의 대기 자료 오차는 0.1%이내로 측정 되었다.

• 품질경영학회지
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• 제47권4호
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• pp.701-711
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• 2019

Purpose: The problem of optimizing redundancy allocation in multi-level systems is considered when each item in a multi-level system has alternative items with the same function. The number of redundancy of multi-level system is allocated to maximize the reliability of the system under path set and cost limitation constraints. Methods: Based on cost limitation and path set constraints, a mathematical model is established to maximize system reliability. Particle swarm optimization is employed for redundant allocation and verified by numerical experiments. Results: Comparing the particle swarm optimization method and the memetic algorithm for the 3 and 4 level systems, the particle swarm optimization method showed better performance for solution quality and search time. Particularly, the particle swarm optimization showed much less than the memetic algorithm for variation of results. Conclusion: The proposed particle swarm optimization considerably shortens the time to search for a feasible solution in MRAP with path set constraints. PS optimization is expected to reduce search time and propose the better solution for various problems related to MRAP.

• 한국정보처리학회논문지
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• 제6권10호
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• pp.2809-2815
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• 1999

Level set, and active contour(snakes) models are extensively used for image segmentation or shape extraction in computer vision. Snakes utilize the energy minimization concepts, and level set is based on the curve evolution in order to extract contours from image data. In general, these two models have their own drawbacks. For instance, snake acts pooly unless it is placed close to the wanted shape boundary, and it has difficult problem when image has multiple objects to be extracted. But, level set method is free of initial curve position problem, and has ability to handle topology of multiple objects. Nevertheless, level set method requires much more calculation time compared to snake model. In this paper, we use good points of two described models and also apply multi resolution algorithm in order to speed up the process without decreasing the performance of the shape extraction.

• 한국시뮬레이션학회논문지
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• 제17권3호
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• pp.95-105
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• 2008

본 논문에서는 무선 센서네트워크에서 센서노드의 효율적 인증을 제공하기 위한 다중계층 클러스터 기반의 분산형 인증모델(DAMMC: Distributed Authentication Model using Multi-level Cluster)을 제안한다. 제안된 인증모델은 하나의 클러스터헤드가 CA 기능을 갖되 사용자가 정의한 m개의 다중계층을 두고 상위 클러스터가 하위클러스터를 인증하는 구조로서, 클러스터들끼리의 상호 인증 오버헤드를 해결할 수 있는 기법이다. 특히 노드 인증서 발급의 경우, 임계값 t개 이상의 클러스터 멤버노드가 분할인증서를 제공하는 경우에만 인증서가 생성되도록 비밀분산기법을 사용하여 센서노드의 효과적인 신뢰관계를 구축하였다. 제안된 DAMMC는 시뮬레이션을 통해 초기인증과정에서의 인증발급 연산시간, 노드 추가에 따른 인증발급 연산시간등이 기존 인증프로토콜에 비해 우수함을 확인하였으며, 보안성능도 변형공격, 속임 경로 공격 및 비인가된 노드 추가, 재사용 공격 등의 공격기법으로부터 안전함을 확인하였다.

• Journal of Computing Science and Engineering
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• 제8권2호
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• pp.65-77
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• 2014

To address the problem of multi-target retrieval (MTR) of remote sensing images, this study proposes a new object-level feature representation model. The model provides an enhanced application image representation that improves the efficiency of MTR. Generating the model in our scheme includes processes, such as object-oriented image segmentation, feature parameter calculation, and symbolic image database construction. The proposed model uses the spatial representation method of the extended nine-direction lower-triangular (9DLT) matrix to combine spatial relationships among objects, and organizes the image features according to MPEG-7 standards. A similarity metric method is proposed that improves the precision of similarity retrieval. Our method provides a trade-off strategy that supports flexible matching on the target features, or the spatial relationship between the query target and the image database. We implement this retrieval framework on a dataset of remote sensing images. Experimental results show that the proposed model achieves competitive and high-retrieval precision.