• 한국콘텐츠학회논문지
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• 제8권8호
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• pp.1-8
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• 2008

본 연구에서는 하드웨어적인 인프라 구축 없이도 시스템의 자원과 네트워크 대역폭을 효율적으로 사용할 수 있는 오버레이 기반 멀티캐스트 트리를 이용하여 다수의 사용자들에게 개인 인터넷 방송 서비스를 고품질로 제공할 수 있는 로컬 스왑 기법을 제안하였다. 제안한 기법의 효율성을 검증하기 위해 다양한 오버레이 기반 멀티캐스트 알고리즘 조건 하에서 제안한 기법을 적용하여 QoS(Quality of Service)를 보장하는 개인 인터넷 방송 서비스 정보를 추출하여 비교 분석하였다. 또한 제안한 로컬 스왑 기법의 효율성을 검증하기 위하여 본 논문에서는 다양한 오버레이 기반 멀티캐스트 알고리즘을 시뮬레이션에 적용하여 여러가지 방법으로 비교 분석하였다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집B
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• pp.82-86
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• 2001

This papers deals with feasibility study of wireless motion control. Wireless telecommunication advances with development of IT technology and extends more and more areas. So we selected Bluetooth out of the technologies(Bluetooth, SWAP(SharedWireless Access Protocol), IrDA(Infra Red Data Association), WLAN(Wireless Local Area Network)) which was developed for local data communication and set up simple experimental system for wireless data transfer and server and client program for wireless data transfer was wrote. We successfully transferred some data wirelessly with this program.

• 한국컴퓨터정보학회논문지
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• 제26권10호
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• pp.27-35
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• 2021

지역 탐색은 다양한 조합 최적화 문제들을 해결하기 위해 활용되어 왔다. 지역 탐색에 있어서 가장 중요한 요소 중 하나가 이웃해를 생성하는 방법이다. 본 논문에서는 순열 기반 조합 최적화를 위한 지역 탐색의 이웃해 생성 전략들을 제안하고, 순회 외판원 문제를 대상으로 각 전략들의 성능을 비교한다. 본 논문에서는 총 10가지 이웃해 생성 전략을 제안한다. 기본적으로 기존에 많이 사용했던 Swap 등 4가지 전략 이외에 Rotation 등 4가지 기법을 새롭게 제안한다. 이외에 기본 이웃해 생성 전략들을 결합하여 만든 Combined1과 Combined2가 있다. 실험은 기본적인 지역 탐색을 적용하되 이웃해 생성 전략만 변경하여 수행하였다. 실험 결과, 이웃해 생성 전략에 따라 성능 차이가 큰 것을 확인하였으며 아울러 Combined2의 성능이 가장 좋음을 확인하였다. 뿐만 아니라 Combined2는 기존의 지역 탐색 기법들보다 더 좋은 성능을 발휘함을 확인하였다.

• KNOM Review
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• 제22권3호
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• pp.25-30
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• 2019

기상 응용의 경우 시간적, 자원적 한계 내에서도 의미 있는 결과를 도출해 제공해야 한다. 수많은 과거 데이터를 통한 예보는 시간적인 소요가 크며, 국지성 태풍 예보와 같은 재난 안전 관련 분석/예측의 경우에는 여전히 자원적 한계가 존재한다. 태풍 예보, 도로별 침수/홍수 지역 예측 서비스 등 시간 제약하에 결과를 도출해야 하는 경우와 제한적인 물리적 환경 조건으로 인해 발생하는 문제 없이 적합한 예보를 제공해야 한다. 본 논문에서는 시간적, 자원적 조건에서도 원활한 예보 서비스 제공을 위해 기상 및 기후 예측 응용을 분석한다. 격자 크게 따른 수행 시간 분석을 통해 격자 조절을 통해 시간적 제약 조건이 있는 경우에 대처할 수있음을 확인하였다. 또한 메모리 자원 조절을 통해 수행 시간을 분석하여 성능에 영향을 미치지 않는 최소 자원 조건을 확인하였으며 swap, mlock 분석을 통해 응용의 자원 사용 패턴을 확인하였다.

• International Journal of Computer Science & Network Security
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• 제23권6호
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• pp.193-201
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• 2023

In this paper, we consider the maximum scatter traveling salesman problem (MSTSP), a travelling salesman problem (TSP) variant. The problem aims to maximize the minimum length edge in a salesman's tour that travels each city only once in a network. It is a very complicated NP-hard problem, and hence, exact solutions can be found for small sized problems only. For large-sized problems, heuristic algorithms must be applied, and genetic algorithms (GAs) are found to be very successfully to deal with such problems. So, this paper develops a hybrid GA (HGA) for solving the problem. Our proposed HGA uses sequential sampling algorithm along with 2-opt search for initial population generation, sequential constructive crossover, adaptive mutation, randomly selected one of three local search approaches, and the partially mapped crossover along with swap mutation for perturbation procedure to find better quality solution to the MSTSP. Finally, the suggested HGA is compared with a state-of-art algorithm by solving some TSPLIB symmetric instances of many sizes. Our computational experience reveals that the suggested HGA is better. Further, we provide solutions to some asymmetric TSPLIB instances of many sizes.

• 한국콘텐츠학회:학술대회논문집
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• 한국콘텐츠학회 2010년도 춘계 종합학술대회 논문집
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• pp.405-407
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• 2010

IP 멀티캐스트의 대안으로 제시되어지는 오버레이 멀티캐스트는 기존 라우터들을 변경할 필요 없이 응용 계층에서 라우팅을 실시하여 시스템의 자원과 네트워크 대역폭을 효율적으로 사용할 수 있는 기법으로 중간 노드의 이탕이 발생하게 될 경우 멀티캐스트 트리를 재구성 한다. 그러나 빈번한 멀티캐스트 트리의 재구성은 심각한 성능 저하를 가져오게 된다. 본 논문에서는 이러한 성능저하를 보완하기 위해 각 자식 노드들로부터 소스 노드에게 주기적으로 피드백 되어오는 정보를 기반으로 트리 성능 최적화 알고리즘을 제안한다.

• 대한산업공학회지
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• 제26권2호
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• pp.155-164
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• 2000

Recently Fiber-optic Micro-cellular Wireless Network is considered to solve frequent handoffs and local traffic unbalance in microcellular systems. In this system, central station which is connected to several microcells by optical fiber manages the channels. We propose an efficient sectorization algorithm which dynamically clusters the microcells to minimize the blocked and handoff calls and to balance the traffic loads in each cell. The problem is formulated as an integer linear programming. The objective is to minimize the blocked and handoff calls. To solve this real time sectorization problem the Tabu Search is considered. In the tabu search intensification by Swap and Delete-then-Add (DTA) moves is implemented by short-term memory embodied by two tabu lists. Diversification is considered to investigate proper microcells to change their sectors. Computational results show that the proposed algorithm is highly effective. The solution is almost near the optimal solution and the computation time of the search is considerably reduced compared to the optimal procedure.

• Industrial Engineering and Management Systems
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• 제7권2호
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• pp.171-181
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• 2008

Home care, known also as domiciliary care, is part of the community care service that is a responsibility of the local government authorities in the UK as well as many other countries around the world. The aim is to provide the care and support needed to assist people, particularly older people, people with physical or learning disabilities and people who need assistance due to illness to live as independently as possible in their own homes. It is performed primarily by care workers visiting clients' homes where they provide help with daily activities. This paper is concerned with the dispatching of care workers to clients in an efficient manner. The optimized routine for each care worker determines a schedule to achieve the minimum total cost (in terms of distance traveled) without violating the capacity and time window constraints. A collaborative population-based meta-heuristic called Particle Swarm Optimization (PSO) is applied to solve the problem. A particle is defined as a multi-dimensional point in space which represents the corresponding schedule for care workers and their clients. Each dimension of a particle represents a care activity and the corresponding, allocated care worker. The continuous position value of each dimension determines the care worker to be assigned and also the assignment priority. A heuristic assignment scheme is specially designed to transform the continuous position value to the discrete job schedule. This job schedule represents the potential feasible solution to the problem. The Earliest Start Time Priority with Minimum Distance Assignment (ESTPMDA) technique is developed for generating an initial solution which guides the search direction of the particle. Local improvement procedures (LIP), insertion and swap, are embedded in the PSO algorithm in order to further improve the quality of the solution. The proposed methodology is implemented, tested, and compared with existing solutions for some 'real' problem instances.

• 산업경영시스템학회지
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• 제28권2호
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• pp.8-17
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• 2005

This paper dealt with a kind of heterogeneous vehicle routing problem with known demand and time deadline of customers. The customers are supposed to have one of tight deadline and loose deadline. The demand of customers with tight deadline must be fulfilled in the deadline. However, the late delivery is allowed to customers with loose deadline. That is, the paper suggests a model to minimize total acquisition cost, total travel distance and total violation time for a fleet size and mix vehicle routing problem with time deadline, and proposes a heuristic algorithm for the model. The proposed algorithm consists of two phases, i.e. generation of an initial solution and improvement of the current solution. An initial solution is generated based on a modified insertion heuristic and iterative Improvement procedure is accomplished using neighborhood generation methods such as swap and reallocation. The proposed algorithm is evaluated using a well known numerical example.

• 한국지능시스템학회:학술대회논문집
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• 한국퍼지및지능시스템학회 2003년도 ISIS 2003
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• pp.187-190
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• 2003

Many manufacturing companies consider the integrated and concurrent scheduling because they need the global optimization technology that could manufacture various products more responsive to customer needs. In this paper, we propose an advanced scheduling model to generate the schedules considering resource constraints and precedence constraints in make-to-order (MTO) manufacturing environments. Precedence of work- in-process(WIP) and resources constraints have recently emerged as one of the main constraints in advanced scheduling problems. The advanced scheduling problems is formulated as a multiobjective mathematical model for generating operation schedules which are obeyed resources constraints, alternative workstations of operations and the precedence constraints of WIP in MTO manufacturing. For effectively solving the advanced scheduling problem, the multi-objective hybrid genetic algorithm (m-hGA) is proposed in this paper. The m-hGA is to minimize the makespan, total flow time of order, and maximum tardiness for each order, simultaneously. The m-hGA approach with local search-based mutation through swap mutation is developed to solve the advanced scheduling problem. Numerical example is tested and presented for advanced scheduling problems with various orders to describe the performance of the proposed m-hGA.