• 한국정보처리학회논문지
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• 제3권1호
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• pp.43-54
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• 1996

이 논문은 새로운 휴리스틱 탐색(heuristic search)방법을 이용하여, 수평 및 수 직선으로 이루어진 방해 물들이 놓인 가운데 수평 및 수직선으로 구성된 최단 거리 (rectilinear shortestpath)와 꺾이는회수가 가장 적은최소 꺾임경로(link metric shortest path) 및 이 둘을 혼합시킨 혼합형 최단 경로를 구하는 알고리즘을 서술 하고 있다. 최단 경로를 구하는 방법으로 미로 찾기형 알고리즘(maze-running algorithms)과 선형 탐색 알고리즘(line-search algorithms)의 장점만을 이용한 GMD 알고리즘(Guided Minimum Detour algorithm)을 제안하고 있으며 이를 더욱 효율 적으 로 개선한 LGMD 알고리즘 (Line-by-Line Guided Minimum Detour algorithmm)을 개발 하였다. 이들 GMD와 LGMD 알고리즘은 기존의 최단 경로를 내포하고 있는 conection group를 이용하지 않고서도 휴리스틱을 사용한 guided A 탐색(guided A* search)을 이용하여 최적의 최단 경로를 구할 수 있는 장점이 있으며 시간과 메모리 면에서 효 율을 극대화하였다. 이들 GMD와 LGMD 알고리즘은 각각 O(m＋eloge＋NlogN)와 O(eloge＋ NlogN)의 시간과 O(e＋N)의 메모리를 사용한다. 여기서 m은 탐색에 사용된 지선 (line segment)들의 수이다. 또한 LGMD는 최소 꺾임 경로(link metric shortest path)와 최단 경로와 최소의 꺾임을 조합한 혼합형 최단 경로를 구하는 데에도 적용될 수 있는 확장성을 가지고 있다.

• 대한안전경영과학회지
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• 제10권1호
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• pp.145-153
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• 2008

The vehicle routing problem determines each vehicle routes to find the transportation costs, subject to meeting the customer demands of all delivery points in geography. Vehicle routing problem is known to be NP-hard, and it needs a lot of computing time to get the optimal solution, so that heuristics are more frequently developed than optimal algorithms. This study aims to develop a heuristic method which combines guided local search with a tabu search in order to minimize the transportation costs for the vehicle routing assignment and uses ILOG programming library to solve. The computational tests were performed using the benchmark problems. And computational experiments on these instances show that the proposed heuristic yields better results than the simple tabu search does.

• 로봇학회논문지
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• 제14권1호
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• pp.40-49
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• 2019

Reinforcement learning has been applied to various problems in robotics. However, it was still hard to train complex robotic manipulation tasks since there is a few models which can be applicable to general tasks. Such general models require a lot of training episodes. In these reasons, deep neural networks which have shown to be good function approximators have not been actively used for robot manipulation task. Recently, some of these challenges are solved by a set of methods, such as Guided Policy Search, which guide or limit search directions while training of a deep neural network based policy model. These frameworks are already applied to a humanoid robot, PR2. However, in robotics, it is not trivial to adjust existing algorithms designed for one robot to another robot. In this paper, we present our implementation of Guided Policy Search to the robotic arms of the Baxter Research Robot. To meet the goals and needs of the project, we build on an existing implementation of Baxter Agent class for the Guided Policy Search algorithm code using the built-in Python interface. This work is expected to play an important role in popularizing robot manipulation reinforcement learning methods on cost-effective robot platforms.

• 산업경영시스템학회지
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• 제29권3호
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• pp.62-69
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• 2006

Vehicle routing problem with time windows is determined each vehicle route in order to minimize the transportation costs. All delivery points in geography have various time restriction in camparision with the basic vehicle routing problem. Vechicle routing problem with time windows is known to be NP-hard, and it needs a lot of computing time to get the optimal solution, so that heuristics are more frequently developed than optimal algorithms. This study aims to develop a heuristic method which combines guided local search with a tabu search in order to minimize the transportation costs for the vehicle routing assignment and uses ILOG programming library to solve. The computational tests were performed using the benchmark problems.

• 전기학회논문지
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• 제61권2호
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• pp.216-222
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• 2012

Newly proposed RG-MADS (Randomly Guided Mesh Adaptive Direct Search) has been applied to the optimal design of Interior Permanent Magnet Synchronous Motor (IPMSM) which has the distinctive features of magnetic saturation. RG-MADS, advanced from classical MADS algorithm, has the superiority in computational time and reliable convergence accuracy to the optimal solution, thus it is appropriate to the optimal design of IPMSM coupled with time-consuming Finite Element Analysis (FEA), necessary to the nonlinear magnetic application for better accuracy. Effectiveness of RG-MADS has been verified through the well-known benchmark-functions beforehand. In addition, the proposed RG-MADS has been applied to the optimal design of IPMSM aiming at maximizing the Maximum Torque Per Ampere (MTPA), which is regarded as representative design goal of IPMSM.

• Management Science and Financial Engineering
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• 제15권1호
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• pp.81-96
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• 2009

Data mining, specially clustering is one of exciting research areas for ant based algorithms. Ant clustering algorithm, however, has many difficulties for resolving practical situations in clustering. We propose a new grid-based ant colony algorithm for clustering of data. The previous ant based clustering algorithms usually tried to find the clusters during picking up or dropping down process of the items of ants using some stigmergy information. In our ant clustering algorithm we try to make the ants reflect neighborhood information within the storage nests. We use two ant classes, search ants and labor ants. In the initial step of the proposed algorithm, the search ants try to guide the characteristics of the storage nests. Then the labor ants try to classify the items using the guide in-formation that has set by the search ants and the stigmergy information that has set by other labor ants. In this procedure the clustering decision of ants is quickly guided and keeping out of from the stagnated process. We experimented and compared our algorithm with other known algorithms for the known and statistically-made data. From these experiments we prove that the suggested ant mining algorithm found the clusters quickly and effectively comparing with a known ant clustering algorithm.

• 통합자연과학논문집
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• 제3권3호
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• pp.143-147
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• 2010

Since it is of great importance to know how a ligand binds to a receptor, there have been a lot of efforts to improve the quality of prediction of docking poses. Earlier efforts were focused on improving search algorithm and scoring function in a docking program resulting in a partial improvement with a lot of variations. Although these are basically very important and essential, more tangible improvements came from the reduction of search space. In a normal docking study, the approximate active site is assumed to be known. After defining active site, scoring functions and search algorithms are used to locate the expected binding pose within this search space. A good search algorithm will sample wisely toward the correct binding pose. By careful study of receptor structure, it was possible to prioritize sub-space in the active site using "receptor-based pharmacophores" or "hot spots". In a sense, these techniques reduce the search space from the beginning. Further improvements were made when the bound ligand structure is available, i.e., the searching could be directed by molecular similarity using ligand information. This could be very helpful to increase the accuracy of binding pose. In addition, if the biological activity data is available, docking program could be improved to the level of being useful in affinity prediction for a series of congeneric ligands. Since the number of co-crystal structures is increasing in protein databank, "Ligand-Guided Docking" to reduce the search space would be more important to improve the accuracy of docking pose prediction and the efficiency of virtual screening. Further improvements in this area would be useful to produce more reliable docking programs.

• Advances in robotics research
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• 제2권1호
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• pp.1-11
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• 2018

To monitor the environment and determine the source of a pollutant gradient using a multiple robot swarm, we propose a hybrid algorithm that combines two bio-inspired algorithms mimicking chemotaxis and pheromones of bacteria. The algorithm is implemented in virtual robot agents in a simulator to evaluate their feasibility and efficiency in gradient maps with different sizes. Simulation results show that the chemotaxis controller guided robot agents to the locations with higher pollutant concentrations, while the pheromone marked in a virtual field increased the efficiency of the search by reducing the visiting redundancy. The number of steps required to reach the target point did not increase proportionally as the map size increased, but were less than those in the linear whole-map search method. Furthermore, the robot agents could function with simple sensor composition, minimum information about the map, and low calculation capacity.

• 정보처리학회논문지B
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• 제9B권6호
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• pp.745-752
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• 2002

본 논문은 이 기종간의 표준 압축형식을 변환하는데 있어 실시간 변환이 가능하도록 하며 프레임의 특성을 이용하여 압축률을 좀 더 높여 보는데 그 목적을 두고 있다. 이 기종간의 표준 압축형식 변환으로는 압축률이 낮은 MPEG2에서 압축률이 높은 H.263으로의 변환을 시도하였다. MPEG2에서 H.263으로 변환한 후 좀 더 압축률을 높이기 위하여 분석한 결과 MPEG2의 P 프레임내의 인트라 매크로블록 수가 H.263의 P 프레임의 인트라 매크로블록보다 많다는 것을 알 수 있었다. 인트라 매크로블록은 P 프레임을 생성하는 과정에서 움직임 예측 과정의 결과치가 임계치에 미치지 못했을 경우에 생성되는 것으로써 공간적인 압축 과정을 통하여 압축되기 때문에 P 프레임의 압축률에 큰 영향을 준다. 따라서 본 논문에서는 P 프레임의 압축률을 높이기 위하여 MPEG2 P 프레임에 생성된 인트라 매크로블록의 개수를 줄여 보았다. 이를 위한 해결방법으로써 P 프레임내의 인트라 매크로블록 변환 과정에 움직임 예측 과정을 삽입하여 변환하였다. 그리고 움직임 예측 과정의 복잡도를 줄이기 위하여 복원과정에서 알 수 있는 이웃하는 매크로블록의 정보와 움직임 벡터 정보를 이용하여 가이드 탐색 방법을 제안하였다. 실험 결과 MPEG2에서 H.263으로 변환이 실시간으로 이루어짐을 확인하였다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.273-277
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• 2003

A general process of electronic assembly is composed of a series of geometric alignments and bonding/screwing processes. After assembly, the function is tested in a following process of inspection. However, assembly of micro-optic devices requires both processes to be performed in equipment. Coarse geometric alignment is made by using vision and optical function is improved by the following fine motion based on feedback of tunable laser interferometer. The general system is composed of a precision robot system for 3D assembly, a 3D vision guided system for geometric alignment and an optical feedback system with a tunable laser. In this study, we propose a new fast alignment algorithm of micro-optic devices for both of visual and optical alignments. The main goal is to find a fastest alignment process and algorithms with state-of-the-art technology. We propose a new approach with an optimal sequence of processes, a visual alignment algorithm and a search algorithm for an optimal optical alignment. A system is designed to show the effectiveness and efficiency of the proposed method.