• Title/Summary/Keyword: Local Search Methods

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Efficient Path Search Method using Ant Colony System in Traveling Salesman Problem (순회 판매원 문제에서 개미 군락 시스템을 이용한 효율적인 경로 탐색)

  • 홍석미;이영아;정태충
    • Journal of KIISE:Software and Applications
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    • v.30 no.9
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    • pp.862-866
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    • 2003
  • Traveling Salesman Problem(TSP) is a combinational optimization problem, Genetic Algorithm(GA) and Lin-Kernighan(LK) Heuristic[1]that is Local Search Heuristic are one of the most commonly used methods to resolve TSP. In this paper, we introduce ACS(Ant Colony System) Algorithm as another approach to solve TSP and propose a new pheromone updating method. ACS uses pheromone information between cities in the Process where many ants make a tour, and is a method to find a optimal solution through recursive tour creation process. At the stage of Global Updating of ACS method, it updates pheromone of edges belonging to global best tour of created all edge. But we perform once more pheromone update about created all edges before global updating rule of original ACS is applied. At this process, we use the frequency of occurrence of each edges to update pheromone. We could offer stochastic value by pheromone about each edges, giving all edges' occurrence frequency as weight about Pheromone. This finds an optimal solution faster than existing ACS algorithm and prevent a local optima using more edges in next time search.

A Neighbor Selection Technique for Improving Efficiency of Local Search in Load Balancing Problems (부하평준화 문제에서 국지적 탐색의 효율향상을 위한 이웃해 선정 기법)

  • 강병호;조민숙;류광렬
    • Journal of KIISE:Software and Applications
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    • v.31 no.2
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    • pp.164-172
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    • 2004
  • For a local search algorithm to find a bettor quality solution it is required to generate and evaluate a sufficiently large number of candidate solutions as neighbors at each iteration, demanding quite an amount of CPU time. This paper presents a method of selectively generating only good-looking candidate neighbors, so that the number of neighbors can be kept low to improve the efficiency of search. In our method, a newly generated candidate solution is probabilistically selected to become a neighbor based on the quality estimation determined heuristically by a very simple evaluation of the generated candidate. Experimental results on the problem of load balancing for production scheduling have shown that our candidate selection method outperforms other random or greedy selection methods in terms of solution quality given the same amount of CPU time.

Comparison of Estimating Parameters by Univariate Search and Genetic Algorithm using Tank Model (단일변이 탐색법과 유전 알고리즘에 의한 탱크모형 매개변수 결정 비교 연구)

  • Lee, Sung-Yong;Kim, Tae-Gon;Lee, Je-Myung;Lee, Eun-Jung;Kang, Moon-Seong;Park, Seung-Woo;Lee, Jeong-Jae
    • Journal of The Korean Society of Agricultural Engineers
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    • v.51 no.3
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    • pp.1-8
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    • 2009
  • The objectives of this study are to apply univariate search and genetic algorithm to tank model, and compare the two optimization methods. Hydrologic data of Baran watershed during 1996 and 1997 were used for correction the tank model, and the data of 1999 to 2000 were used for validation. RMSE and R2 were used for the tank model's optimization. Genetic algorithm showed better result than univariate search. Genetic algorithm converges to general optima, and more population of potential solution made better result. Univariate search was easy to apply and simple but had a problem of convergence to local optima, and the problem was not solved although search the solution more minutely. Therefore, this study recommend genetic algorithm to optimize tank model rather than univariate search.

A Performance Analysis of Routing Protocols Avoiding Route breakages in Ad hoc Networks (애드 흑 네트워크에서 경로 손실 회피 라우팅 프로토콜의 성능평가)

  • Wu Mary;Jung Sang Joon;Jung Youngseok;Kim Chonggun
    • Journal of KIISE:Information Networking
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    • v.33 no.1
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    • pp.49-58
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    • 2006
  • When the movement of a node breaks the route in ad-hoc network, on-demand routing protocol performs the local route recovery or a new route search for the route maintenance. And when it performs the new route search or the local search, the packet which is transmitted can be delayed. There are ARMP and RPAODV as the methods reducing the delay resulted from the route-breakage. They predict the route-breakage and construct an alterative local route before the occurrence of the route-breakage. When the link state is unstable, the success rate of the alternative local route that can avoid the route-breakage can give a direct effect on the route-breakage and the transmission delay, To estimate the performance of routing protocols avoiding route-breakage, we suggest the numerical formulas of AODV, the representative on-demand routing protocol, and ARMP, RPAODV. To verify the efficiency and accuracy of the proposed numerical formulas, we analysis and compare with the results of the computer simulation and that of the numerical formulas.

Fast Integer-Pel Motion Estimation Based on Statistical Property for H.264/AVC (H.264/AVC를 위한 통계 특성 기반 정수 화소 단위 고속 움직임 예측 기법)

  • Noh, Jin-Young;Hong, Min-Cheol
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.37 no.8A
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    • pp.669-678
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    • 2012
  • In this paper, we propose an efficient fast integer-pel motion estimation for H.264/AVC using local statistics of local motion vectors. Using neighboring motion vectors, we define a new statistical property that is used to determine a mode of motion search range of current block. In addition, an adaptive motion search range compensated method that is based on cumulative statistics of previous coded blocks is addressed to solve the problem of the statistical motion search range decision method. Experimental results show that proposed algorithm has the capability to reduce the computational cost over the other methods.

Novel Method for Face Recognition using Laplacian of Gaussian Mask with Local Contour Pattern

  • Jeon, Tae-jun;Jang, Kyeong-uk;Lee, Seung-ho
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.10 no.11
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    • pp.5605-5623
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    • 2016
  • We propose a face recognition method that utilizes the LCP face descriptor. The proposed method applies a LoG mask to extract a face contour response, and employs the LCP algorithm to produce a binary pattern representation that ensures high recognition performance even under the changes in illumination, noise, and aging. The proposed LCP algorithm produces excellent noise reduction and efficiency in removing unnecessary information from the face by extracting a face contour response using the LoG mask, whose behavior is similar to the human eye. Majority of reported algorithms search for face contour response information. On the other hand, our proposed LCP algorithm produces results expressing major facial information by applying the threshold to the search area with only 8 bits. However, the LCP algorithm produces results that express major facial information with only 8-bits by applying a threshold value to the search area. Therefore, compared to previous approaches, the LCP algorithm maintains a consistent accuracy under varying circumstances, and produces a high face recognition rate with a relatively small feature vector. The test results indicate that the LCP algorithm produces a higher facial recognition rate than the rate of human visual's recognition capability, and outperforms the existing methods.

Importance-Performance Analysis of Mountain Village Promotion Projects in the Forest Sector by Upper-Level Local Governments

  • Kang, Byung-Hoon;Kim, Seong-Hak;Chae, Jin-Hae
    • Journal of People, Plants, and Environment
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    • v.24 no.6
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    • pp.707-718
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    • 2021
  • Background and objective: Due to the recent crisis of extinction in local areas, the mountain village promotion policy is recognized as an important task. This study examined the priorities of major policy projects in the forest sector that affect mountain village promotion. Methods: For research methods, literature search, expert advisory meetings, and a survey were conducted. The survey was conducted on 42 policy stakeholders from June 1 to August 13, 2021. The literature search was based on policy projects in the forest sector by 8 upper-level local governments including mountain villages. For questionnaire items, 173 forest policy projects were classified into 27 types through expert review, and the importance and performance of each type were rated on a 5-point Likert scale. Paired t-test, IPA, Locus for Focus model, and Borich needs assessment were used as the analysis methods, and the statistical program SPSS 21.0 was used as the analytical tool. Results: The results showed that 'creating forest-related jobs' and 'supporting cultivation of professional forestry workers' both showed high importance and performance, implying that they would show an effect in mountain village promotion. 'Creating forests for environmental improvement', 'discovering forest cultural assets' 'establishing and boosting forest tourism', 'providing forest therapy services', 'creating forest-related jobs', 'supporting community revitalization', and 'urban-rural exchanges' were found to be the types that needed improvement and concentration for mountain village promotion. In particular, 'creating forests for environmental improvement' and 'discovering forest cultural assets' were derived as priority considerations for mountain village promotion policies. Conclusion: In summary, it was found that in order to promote mountain villages, various content projects must be improved and carried out to enhance the physical environment and revitalize mountain villages.

Size Optimization of Space Trusses Based on the Harmony Search Heuristic Algorithm (Harmony Search 알고리즘을 이용한 입체트러스의 단면최적화)

  • Lee Kang-Seok;Kim Jeong-Hee;Choi Chang-Sik;Lee Li-Hyung
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 2005.04a
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    • pp.359-366
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    • 2005
  • Most engineering optimization are based on numerical linear and nonlinear programming methods that require substantial gradient information and usually seek to improve the solution in the neighborhood of a starting point. These algorithm, however, reveal a limited approach to complicated real-world optimization problems. If there is more than one local optimum in the problem, the result may depend on the selection of an initial point, and the obtained optimal solution may not necessarily be the global optimum. This paper describes a new harmony search(HS) meta-heuristic algorithm-based approach for structural size optimization problems with continuous design variables. This recently developed HS algorithm is conceptualized using the musical process of searching for a perfect state of harmony. It uses a stochastic random search instead of a gradient search so that derivative information is unnecessary. Two classical space truss optimization problems are presented to demonstrate the effectiveness and robustness of the HS algorithm. The results indicate that the proposed approach is a powerful search and optimization technique that may yield better solutions to structural engineering problems than those obtained using current algorithms.

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Fast Block Motion Estimation Using the Characteristics of the Motion in Search Region (탐색 영역에서의 움직임 특성을 이용한 고속 블록 움직임 추정)

  • 최정현;박대규;정태연;이경환;이법기;김덕규
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.25 no.1B
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    • pp.167-174
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    • 2000
  • The three-step search(TSS) algorithm, a simple and gradual motion estimation algorithm, has been widely used in some low bit-rate video compression. We propose a new fast block motion estimation algorithm using the characteristics of motion in search region. Most of motion vectors exist in the center region of search area, so the notion in that region is examined more closely than TSS in this paper. Also in a search step, motion vector is estimated in the local area which is not overlapped with the search area in previous step, considering the all possible direction of motion. Therefore, we get the better motion estimation and reduce computational time in compared with the conventional methods.

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A Research on the improvement measures about Community-based Korean medical public health service in public service center (보건소 한방지역보건사업의 개선방안에 대한 연구)

  • Choi, Kwang-Jin;Kim, Hong-Jun;Ahn, Sang-Woo
    • Korean Journal of Oriental Medicine
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    • v.10 no.1
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    • pp.107-117
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    • 2004
  • Each Local public heal public health service center is in difficult situation on programing and performing of local public health service. The purpose of research is to inquire of the present state of local public health service and search long-term developmental methods. The first, in order to accomplish this purpose, I distributed questionnaires to Korean medical doctors, who are worked in public health service center and researched that. The second, based on these findings, I proposed planning for upcoming project for activating local public health service on Korean medicine.

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