• 한국경영과학회지
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• 제25권1호
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• pp.67-84
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• 2000

In this paper, we address a network design problem including the decision of hub facility locatiions which is typically found in a communicatio and a transportation network design studies. Due to the administrative and the geographical restrictions, it is common to assume that each user should be assigned to only one hub facility. To construct such a network, three types of network costs should be considered: the fixed costs of establishing the hubs and the arcs in the network, and the variable costs associated with transversing the network. The complex problem is formulated as a mixed IP embedding a multicommodity flow problem. Exploiting its special structure, a dual-based heuristic is then developed, which yields near-optimal design plans. The test results indicate that the heuristic is an effective way to solve this computationally complex problem.

• 대한전기학회논문지
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• 제40권8호
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• pp.731-740
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• 1991

This paper presents a knowledge based system to solve reactive power/voltage control problem in a power system. The methods to reduce inference time are proposed in inferring the solution of problem in the knowledge base which consists of heuristic rules and inowledge of experts. A set of indices drawn from the heuristic knowledge on the power system is utilized to make up for the defect of existing knowledge based systems which determine both the location and the amount of reactive power compensation devices. The concept of set of indices developed in this paper makes it possible to infer the amount of reactive power source only since the bus order list representing priority for the location of reactive power compensator to be switched on can be determined in advance. From the fact that there exists a relationship between the system voltage pattern and the reactive power pattern in operation, the pattern recognition technique is introduced to reduce the inference time in solving the severe voltage problem. To demonstrate the usefulness of the proposed knowledge based system, the IEEE 30 bus system is chosen as a sample system. The results of case study are also presented.

• 대한산업공학회지
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• 제31권4호
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• pp.303-315
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• 2005

In this paper we address a design problem for hub-and-spoke networks and then consider a capacitated hub locations problem with direct shipment (CHLPwD). We determine the location of hubs, the allocation of nodes to hubs, and direct shipment paths in the network, with the objective of minimizing the total cost in the network. In this paper, CHLPwD is formulated as 0-1 integer programming. We develop an evolutionary algorithm here to solve the large sized CHLPwD. To do this, we present the representation and the genetic operators suitable for the problem and propose a heuristic method for the allocation of nodes to hubs. To enhance the search capability, problem-specific information is used in our evolutionary algorithm. The proposed algorithm is compared with the heuristic method in terms of solution quality and computation time. The experimental results show that our algorithm can provide better solutions than the heuristic.

• 한국수학교육학회지시리즈D:수학교육연구
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• 제24권3호
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• pp.175-199
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• 2021

The Science Writing Heuristic (SWH) approach is described as an immersive argument-based science inquiry focusing particularly on learning through epistemic practices. In the literature, several previous studies indicate how academic achievement is positively influenced by the SWH. In addition to these previous studies, several meta-syntheses of qualitative data have been conducted on this particular topic. With these literatures in mind, a quantitative meta-analysis was conducted with ten studies (N = 724) to examine the effectiveness of the SWH on student achievement in Turkey. To present a thoroughly detailed report, this study also examined the following moderators: grade level, subject area, school location, intervention length, and report source. Overall, this study found that in Turkey, the SWH classrooms performed better in academic achievement tests than traditional lecture-based classrooms. Additionally, the SWH is more likely to be effective regardless of grade levels, subject areas, and school locations.

• Spatial Information Research
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• 제18권3호
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• pp.63-72
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• 2010

일반적인 Vehicle Routing Problem with Simultaneous Pick-ups and Deliveries (VRPSPD)는 배송과 수거가 동시에 발생하는 문제를 고려한 차량경로 문제이며, 차량의 운행 거리등의 비용을 최소화하는 것을 결정하는 문제이다. 그러나 기존의 VRPSPD는 이미 차량이 출발하기 전에 경로가 정해져 있어서 차량 운행 중 발생하는 고객의 수거 요청을 기존의 경로에 효율적으로 추가하여 서비스하기가 어렵다. 따라서 본 논문에서는 이러한 문제를 위치기반의 서비스를 이용하여 이동 중인 차량의 위치정보를 파악하고 이를 바탕으로 실시간 재경로 탐색을 통해 해결하는 휴리스틱을 제안한다. 그리고 실험을 통해 기존의 방식과 비교하여 차량을 운행하는데 소요되는 비용을 줄이는 결과를 보였다.

• Industrial Engineering and Management Systems
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• 제10권1호
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• pp.24-33
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• 2011

In this paper, we consider the Location-Routing Problem with simultaneous pickup and delivery (LRPSPD) which is a general case of the location-routing problem. The LRPSPD is defined as finding locations of the depots and designing vehicle routes in such a way that pickup and delivery demands of each customer must be performed with same vehicle and the overall cost is minimized. Since the LRPSPD is an NP-hard problem, we propose a hybrid heuristic approach based on genetic algorithms (GA) and simulated annealing (SA) to solve the problem. To evaluate the performance of the proposed approach, we conduct an experimental study and compare its results with those obtained by a branch-and-cut algorithm on a set of instances derived from the literature. Computational results indicate that the proposed hybrid algorithm is able to find optimal or very good quality solutions in a reasonable computation time.

• 대한토목학회논문집
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• 제33권5호
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• pp.1989-1998
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• 2013

최근 '자전거이용 활성화'가 서서히 사회적으로 중요성이 부각되면서 자전거 중심의 교통체계로의 전환을 위한 다양한 노력이 있어 왔으나 그 효과는 부진한 면이 있다. 본 연구에서는 자전거 주차장 등의 시설을 구축하는 데 있어서 필요한 주차장입지선정을 공학적 분석을 통해서 구현하여 보자는데 있다. 즉, 자전거 주차장의 최적 개수 및 위치를 찾는 방법을 제안하는 것이 목적인 바, 구축 모형은 Heuristic P-Median 알고리즘을 이용하였으며, 예산제약의 유무에 따라 모형을 각각 제시하였다. 모형의 적용을 위하여 시험 네트워크를 구축하고 30개의 예비 주차장 (센트로이드-수요지)을 구성하였다. 분석 결과 자전거 주차장의 입지점은 예산제약이 있는 경우 9개, 예산제약이 없는 경우 20개로 선정되었으며, 선정된 입지점들은 실제 자전거 주차장의 이용률이 높은 곳과 일치하는 것으로 나타났다. 이러한 알고리즘은 실제 공용자전거 등의 대상지, 또는 신규 예상입지선정에 활용되어 질 수 있을 것으로 판단된다. 약간의 한계와 향후연구과제에 대해서도 논하였다.

• Smart Structures and Systems
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• 제13권3호
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• pp.389-406
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• 2014

Optimal sensor placement techniques play a significant role in enhancing the quality of modal data during the vibration based health monitoring of civil structures, where many degrees of freedom are available despite a limited number of sensors. The literature has shown a shift in the trends for solving such problems, from expansion or elimination approach to the employment of heuristic algorithms. Although these heuristic algorithms are capable of providing a global optimal solution, their greatest drawback is the requirement of high computational effort. Because a highly efficient optimisation method is crucial for better accuracy and wider use, this paper presents an improved simulated annealing (SA) algorithm to solve the sensor placement problem. The algorithm is developed based on the sensor locations' coordinate system to allow for the searching in additional dimensions and to increase SA's random search performance while minimising the computation efforts. The proposed method is tested on a numerical slab model that consists of two hundred sensor location candidates using three types of objective functions; the determinant of the Fisher information matrix (FIM), modal assurance criterion (MAC), and mean square error (MSE) of mode shapes. Detailed study on the effects of the sensor numbers and cooling factors on the performance of the algorithm are also investigated. The results indicate that the proposed method outperforms conventional SA and Genetic Algorithm (GA) in the search for optimal sensor placement.

• 한국경영과학회지
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• 제18권1호
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• pp.97-117
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• 1993

This paper considers inspection station location problem for a flexible assembly line that consists of multiple stages. By considering the trade-off between locating an station at an "early" stage and at a "late" stage, we have developed some dominance relations on a graph. Based on the dominance relations, we then present an algorithm that finds an optimal inspection plan and a heuristic approach that finds a near-optimal inspection plan. The effectiveness of these two algorithms is demonstrated by two numerical examples. numerical examples.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제12권8호
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• pp.3657-3682
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• 2018

This paper presents a Bluetooth and pedestrian dead reckoning (PDR)-based indoor fusion localization approach (BtPDR) using smartphones. A Bluetooth and PDR-based indoor fusion localization approach can localize the initial position of a smartphone with the received signal strength (RSS) of Bluetooth. While a smartphone is moving, BtPDR can track its position by fusing the localization results of PDR and Bluetooth RSS. In addition, BtPDR can adaptively modify the parameters of PDR. The contributions of BtPDR include: a Bluetooth RSS-based Probabilistic Voting (BRPV) localization mechanism, a probabilistic voting-based Bluetooth RSS and PDR fusion method, and a heuristic search approach for reducing the complexity of BRPV. The experiment results in a real scene show that the average positioning error is < 2m, which is considered adequate for indoor location-based service applications. Moreover, compared to the traditional PDR method, BtPDR improves the location accuracy by 42.6%, on average. Compared to state-of-the-art Wireless Local Area Network (WLAN) fingerprint + PDR-based fusion indoor localization approaches, BtPDR has better positioning accuracy and does not need the same offline workload as a fingerprint algorithm.