• Title/Summary/Keyword: 탐색비용

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Path Finding with Minimum Speed Dynamic Heuristic (최저 속력 동적 휴리스틱을 이용한 경로탐색)

  • Moon, Dae-Jin;Cho, Dae-Soo
    • Journal of Korea Spatial Information System Society
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    • v.10 no.2
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    • pp.35-48
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    • 2008
  • In this paper, we propose a Dynamic Heuristic to reduce the number of node accesses and improve quality of path in the client-based navigation service. The Dynamic Heuristic is to use heuristic data from server that is calculated with traffic data. The server-based navigation service provides a path searched on server and transmits it to client, but we propose that server only provide heuristic data to client. The proposed client searches a path with heuristic transmitted data from server. We present a new algorithm for using Dynamic Heuristic in the path-finding. The algorithm bases Grid Based Path-Finding, and has minimum speed data of edges in grid. It removes several grids whose minimum speed is less than limited speed.

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Analysis of Beam Discovery and Link setup for MXN based mmWave (mmWave기반의 MXN 빔 탐색 및 링크설정 방식 분석)

  • Baek, Seungkwon;Han, Kijun
    • The Journal of the Convergence on Culture Technology
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    • v.5 no.2
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    • pp.381-388
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    • 2019
  • In this paper, we propose a new wireless transport network, which is named as Mobile Xhaul Network(MXN), that is enable to bring cost efficiency of fronthaul, midhaul and backhaul and to make easy installation of 5G Radio Access Network(RAN). For this purpose, we design XDU discovery and xhaul link setup mechanism with MXN architecture and operational procedure. Especially, in this paper, we propose various types of beam discovery mechanisms for mmWave based radio access on XDU and evaluate proposed schemes. The Simulation result shows that threshold based scheme and information based scheme have less than about 50% beam discovery latency compared to full search scheme.

산업단지의 수출경쟁력 향상을 위한 해상물류비용 절감방안 연구

  • Park, Sang-Guk;Yun, Dae-Geun
    • Proceedings of the Korean Institute of Navigation and Port Research Conference
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    • 2015.07a
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    • pp.191-193
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    • 2015
  • 우리나라 산업단지의 수출경쟁력은 중국 등 주변 국가들의 원가에 상대적으로 취약하다. 수출경쟁력 차원에서 원가를 구성하는 항목들은 여러가지가 있겠으나, 원가절감이 가능한 항목은 그리 많지 않다. 본 연구에서는 국내 수출기업들의 수출경쟁력 향상을 위해 해상물류비용의 절감이 가능한 방안을 탐색하여 연구하였다. 특히 해외에서 소금과 같은 살화물을 수입하고 공선으로 나가 다시 수입하는 벌크선의 경우에는 국내에서 공선상태로 나가는 선박을 대상으로 컨테이너 적재가 가능한 겸용선으로 개조하여 운항시에 컨테이너로 수출하는 해상물류비용을 낮출 수 있다. 따라서 산업단지의 수출기업들이 이를 활용하면 해상물류비용을 획기적으로 낮출수 있으므로 수출경쟁력을 향상시킬수 있고, 이러한 절감방안 모델은 정부, 항만운영사업자, 수출기업 및 하역사업자 모두에게 도움이 되는 모델로 해상물류비용을 절감하기 위해 충분한 연구 가치가 있다.

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Mobile robot path planning with A* algorithm and corner movement (A* 알고리즘을 이용한 이동로봇의 경로계획과 코너 주행에 관한 연구)

  • Lee, Jeong-Woong;Choi, Young-Sup;Lee, Chang-Goo
    • Proceedings of the KIEE Conference
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    • 2003.07d
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    • pp.2334-2336
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    • 2003
  • 이동로봇의 주행을 위해서는 주변 환경에 대한 정보와 출발점과 도착점을 기초로 한 경로 탐색 알고리즘이 필요하다. 여러 경로 탐색 알고리즘 중 A* 알고리즘은 주어진 격자로 구성한 환경 정보 지도상에서 시작점과 목표점 두 Node가 주어지면 목표점까지 Node 단위로 탐색을 실시하여 시작점과 목표점 사이에 존재하는 수많은 경로 중 최저의 이동 비용 경로를 찾는 경험적인 알고리즘이다. 본 논문은 로봇의 가상 크기가 지도의 격자 방안 보다 큰 공간상에서 이동로봇의 경로 생성을 위해 격자 단위가 아닌 로봇의 가상 크기 단위로 탐색하도록 A*알고리즘을 보완하였으며 실험 결과 보완된 A* 알고리즘이 격자 단위 탐색으로 생성한 경로보다 로봇의 주행에 더 적합한 경로를 생성하였다. 또한 이동로봇의 코너 주행시 벽과의 충돌 가능성을 최소화 시키는 안전한 주행 방법을 제시하였다.

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Optimization of Stowage Plans for Car Carrier Ships (카캐리어선 화물 선적 계획 최적화)

  • Cho, Hyunsoo;Kim, Taekwang;Ryu, Kwang Ryel
    • Proceedings of the Korean Institute of Navigation and Port Research Conference
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    • 2019.11a
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    • pp.185-186
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    • 2019
  • 카캐리어선에 화물을 선적하기 위해서는 각 화물의 선적 순서와 위치를 결정해야 하며, 이를 선적 계획이라 한다. 선적 계획은 선박의 무게 중심과 공간 손실률, 화물 재취급(re-handling) 횟수를 최소화하도록 수립된다. 최적의 선적 계획을 수립하기 위해서는 여러 후보 선적 계획들을 평가하여 적합도(fitness)가 가장 높은 것을 탐색하여야 한다. 하지만 화물 종류의 수와 도착지의 수가 증가할수록 후보 선적 계획의 수가 증가하게 되어, 탐색 시간과 계산 비용이 커지는 문제가 발생한다. 본 논문에서는 탐색 공간이 매우 큰 환경에서 최적의 선적 계획을 효율적으로 탐색하기 위해 유전 알고리즘(genetic algorithm)을 사용한다. 또한, 선박의 무게 중심과 공간 손실률, 화물 재취급 횟수로 목적 함수(objective function)를 구성하여 최적 선적 계획을 탐색한다. 실험 결과, 휴리스틱(heuristic) 방식보다 공간 손실률과 재취급 횟수가 향상되었으며, 특히 재취급 횟수는 70% 감소하였다.

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Development of a Method for Partial Searching Technique for Optimal Path Finding in the Long Journey Condition (장거리 최적경로탐색을 위한 부분탐색기법 연구)

  • Bae, Sanghoon
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.26 no.3D
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    • pp.361-366
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    • 2006
  • It is widely known that the dynamic optimal path algorithm, adopting real-time path finding, can be supporting an optimal route with which users are satisfied economically and accurately. However, this system has to search optimal routes frequently for updating them. The proposed concept of optimizing search area lets it reach heuristic optimal path rapidly and efficiently. Since optimal path should be increased in proportion to an distance between origin and destination, tremendous calculating time and highly efficient computers are required for searching long distance journey. In this paper, as a result of which the concepts of partial solution and representative path are suggested. It was possible to find an optimal route by decreasing a half area in comparison with the previous method. Furthermore, as the size of the searching area is uniform, comparatively low efficient computer is required for long distance trip.

Evaluating Reverse Logistics Networks with Centralized Centers : Hybrid Genetic Algorithm Approach (집중형센터를 가진 역물류네트워크 평가 : 혼합형 유전알고리즘 접근법)

  • Yun, YoungSu
    • Journal of Intelligence and Information Systems
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    • v.19 no.4
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    • pp.55-79
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    • 2013
  • In this paper, we propose a hybrid genetic algorithm (HGA) approach to effectively solve the reverse logistics network with centralized centers (RLNCC). For the proposed HGA approach, genetic algorithm (GA) is used as a main algorithm. For implementing GA, a new bit-string representation scheme using 0 and 1 values is suggested, which can easily make initial population of GA. As genetic operators, the elitist strategy in enlarged sampling space developed by Gen and Chang (1997), a new two-point crossover operator, and a new random mutation operator are used for selection, crossover and mutation, respectively. For hybrid concept of GA, an iterative hill climbing method (IHCM) developed by Michalewicz (1994) is inserted into HGA search loop. The IHCM is one of local search techniques and precisely explores the space converged by GA search. The RLNCC is composed of collection centers, remanufacturing centers, redistribution centers, and secondary markets in reverse logistics networks. Of the centers and secondary markets, only one collection center, remanufacturing center, redistribution center, and secondary market should be opened in reverse logistics networks. Some assumptions are considered for effectively implementing the RLNCC The RLNCC is represented by a mixed integer programming (MIP) model using indexes, parameters and decision variables. The objective function of the MIP model is to minimize the total cost which is consisted of transportation cost, fixed cost, and handling cost. The transportation cost is obtained by transporting the returned products between each centers and secondary markets. The fixed cost is calculated by opening or closing decision at each center and secondary markets. That is, if there are three collection centers (the opening costs of collection center 1 2, and 3 are 10.5, 12.1, 8.9, respectively), and the collection center 1 is opened and the remainders are all closed, then the fixed cost is 10.5. The handling cost means the cost of treating the products returned from customers at each center and secondary markets which are opened at each RLNCC stage. The RLNCC is solved by the proposed HGA approach. In numerical experiment, the proposed HGA and a conventional competing approach is compared with each other using various measures of performance. For the conventional competing approach, the GA approach by Yun (2013) is used. The GA approach has not any local search technique such as the IHCM proposed the HGA approach. As measures of performance, CPU time, optimal solution, and optimal setting are used. Two types of the RLNCC with different numbers of customers, collection centers, remanufacturing centers, redistribution centers and secondary markets are presented for comparing the performances of the HGA and GA approaches. The MIP models using the two types of the RLNCC are programmed by Visual Basic Version 6.0, and the computer implementing environment is the IBM compatible PC with 3.06Ghz CPU speed and 1GB RAM on Windows XP. The parameters used in the HGA and GA approaches are that the total number of generations is 10,000, population size 20, crossover rate 0.5, mutation rate 0.1, and the search range for the IHCM is 2.0. Total 20 iterations are made for eliminating the randomness of the searches of the HGA and GA approaches. With performance comparisons, network representations by opening/closing decision, and convergence processes using two types of the RLNCCs, the experimental result shows that the HGA has significantly better performance in terms of the optimal solution than the GA, though the GA is slightly quicker than the HGA in terms of the CPU time. Finally, it has been proved that the proposed HGA approach is more efficient than conventional GA approach in two types of the RLNCC since the former has a GA search process as well as a local search process for additional search scheme, while the latter has a GA search process alone. For a future study, much more large-sized RLNCCs will be tested for robustness of our approach.

An Integration of Local Search and Constraint Programming for Solving Constraint Satisfaction Optimization Problems (제약 만족 최적화 문제의 해결을 위한 지역 탐색과 제약 프로그래밍의 결합)

  • Hwang, Jun-Ha
    • Journal of the Korea Society of Computer and Information
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    • v.15 no.5
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    • pp.39-47
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    • 2010
  • Constraint satisfaction optimization problem is a kind of optimization problem involving cost minimization as well as complex constraints. Local search and constraint programming respectively have been used for solving such problems. In this paper, I propose a method to integrate local search and constraint programming to improve search performance. Basically, local search is used to solve the given problem. However, it is very difficult to find a feasible neighbor satisfying all the constraints when we use only local search. Therefore, I introduced constraint programming as a tool for neighbor generation. Through the experimental results using weighted N-Queens problems, I confirmed that the proposed method can significantly improve search performance.

Caregiving Rewards and Costs of Grandmothers Raising Grandchildren (조손가족 조모가 경험하는 손자녀 양육의 보상과 비용)

  • Han, Gyoung-hae;Joo, Ji-hyun;Lee, Jeong-hwa
    • 한국노년학
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    • v.28 no.4
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    • pp.1147-1164
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    • 2008
  • There has been a sharp increase in the number of grandmothers raising grandchildren in contemporary Korean society. However, little is known about the complexity of the experiences of the custodial grandparenting. Most of the studies mainly examined burden/cost and have paid little attention to the positive aspects of custodial grandparenting. In order to overcome this limitation of previous research, this study aims 1) to examine not only the costs but also the rewards of custodial grandparenting and to explore related factors, 2) to develop the typology based on relative rewards-burden perception of grandmothers about custodial grandparenting and explore the group differences. The data were gathered from 449 grandmothers raising their grandchildren as a primary caregiver, using a structured questionnaire. The data were analyzed using descriptive statistics, correlation, hierarchical multiple regression and ANOVA, with SPSS WIN 12.0 program. Main findings are as follows: First, custodial grandmothers report not only care-giving burden such as physical burnout and economic burden but also various rewards such as joy of watching their grandchildren grow and feeling good about themselves to be a help with their adult children, i.e. grandchildren's father or mother. Second, factors related to the level of perceived cost of grandparenting are different from the factors affecting the positive aspects of grandparenting. Third, results of the two by two cross-tab analysis based on the level of rewards and burden show that about 32 percent of the grandparents belong to Type II group(high rewards-low cost). This result is quite contrary to the assumption of previous research focusing mostly on cost and burden of custodial grandparenting. Fourth, four groups were different in terms of grandmother & grandchildren's characteristics. Implications of these results are discussed.

Search Heuristics for Capacitated Refuse Collection Network Design in Reverse Logistics (역방향 로지스틱스에서 용량제약을 고려한 수거망 설계문제에 관한 탐색기법)

  • Kim, Ji-Su;Choi, Hyun-Seon;Lee, Dong-Ho
    • Journal of Korean Society of Industrial and Systems Engineering
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    • v.33 no.1
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    • pp.41-50
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    • 2010
  • 본 논문에서는 수명이 다한 제품이나 소비자가 더 이상 사용하지 않는 폐기품을 다시 재사용하거나 폐기하는데 필요한 일련의 활동을 위한 역방향 로지스틱스에서의 수거망 설계 문제를 다루고 있다. 수거망 설계 문제는 수거지점의 위치와 수요지의 폐기품을 수거 지점에 할당하는 것을 결정하는 문제로 정의할 수 있으며 수거지점은 재활용품이나 폐기품이 위치한 지점 근처에 위치하고 주어진 잠재적인 위치를 중에서 결정하게 된다. 여기서, 각 수거지점은 용량제약이 있어 수거 지점에 할당되는 폐기품의 양에는 제한이 있다. 본 논문에서 다루는 수거망 설계문제에서는 수거지점을 설치하는데 필요한 고정비용과 수요지와 수거지점간의 수송비용의 합을 최소화하는 것을 목적으로 한다. 또한 대상문제를 보다 명확히 설명하기 위하여 징수계획법을 이용한 수리적 모형을 제안하였으며 문제의 복잡도 인하여 타부 서치와 시뮬레이티드 어닐링 두 가지 형태의 탐색기법을 제안하였다. 이들 탐색기법에 대하여 최대 500개의 잠재적 위치를 가지는 문제에 대하여 실험을 수행하였고 실험결과를 제시하였다.