• Journal of Information Technology Applications and Management
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• v.14 no.4
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• pp.1-16
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• 2007

In the microcell- or picocell-based system the frequent movements of the mobile bring about excessive traffics into the networks. A mobile location estimation mechanism can facilitate both efficient resource allocation and better QoS provisioning through handoff optimization. Existing location estimation schemes consider only LOS model and have poor performance in presence of multi-path and shadowing. In this paper we study a novel scheme which can increase estimation accuracy by considering NLOS environment and other multiple decision parameters than the received signal strength.

• Journal of the Korean Operations Research and Management Science Society
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• v.36 no.2
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• pp.1-14
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• 2011

In this paper, we deal with an access network design problem of fiber-to-the-home passive optical network (FTTH-PON). The FTTH-PON network design problem seeks to minimize the total cost of optical splitters and cables that provide optical connectivity between central office and subscribers. We develop a flow-based mixed integer programming (MIP) model with nonlinear link cost. By developing valid inequalities and preprocessing rules, we enhance the strength of the proposed MIP model in generating tight lower bounds for the problem. We develop an effective Tabu Search (TS) heuristic algorithm that provides good quality feasible solutions to the problem. Computational results demonstrate that the valid inequalities and preprocessing rules are effective for improving the LP-relaxation lower bound and TS algorithm finds good quality solutions within reasonable time bounds.

• Journal of Korean Society of Rural Planning
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• v.9 no.4 s.21
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• pp.43-51
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• 2003

This study aims to integrate the simulation models for rural settlement planning (SimRusep) in the district level (Myon) area of rural counties. The SimRusep, which has two modules of key villages selection and spatial planning for the selected villages, consists of four sub-models such as the spatial location-allocation model of center villages (SLAMCV), the potential centrality evaluation model (PCEM), the land use planning model (LUPM), and the 3-dimensional spatial planning modeller (3DSPLAM). Basically, map data of the integrated system which can be operated on the UNIX environment is inputted and treated using GIS (ARC/INFO) and then its village planning results is graphically presented on the AutoCAD. In order to verify the practical applicabilities of the SimRusep, an administrative area, Ucheon-myun, HoengSung-gun, KangWon-do, was selected as a case study area. It was well operated in the strategic application trials considering application of each sub-model in the study area. The operation results of the SimRusep showed the possibilities of realtime simulation from the selection of key village to its final stereoscopic presentation of planned results. Alternative village plan proposals can be swiftly drafted, which means very practical support for decision making process and public participation.

• Journal of Preventive Medicine and Public Health
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• v.29 no.2 s.53
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• pp.215-225
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• 1996

Decentralization to local governments and amending of Health Center Law are to promote the efforts of health planning at the level of local agencies. In the health facility planning, it is important to take into account that what to be built, where to be located, how far should be service area and so forth, because health facilities are immovable, and require capital as well as personnel and consumable supplies. The aim of our study, answering to the question of 'where to be located?', is to determine the best location of urban health sub-center. At the local level, planning is the matter of finding the best location of specific facilitiy, in relation to population needs. We confine the accessibility, which is basic to location planning, to geographic one. Location-Allocation Model is used to solve the problem where the location is to maximize geographic accessibility. To minimize the weighted travel distance, objective function, $R_k=\sum{\sum}a_{ij}w_{i}d_{ij}$ is used. Distances are measured indirectly by map measure-meter with 1:25,000 Suwon map, and each potential sites, 10 administrative Dongs in Kwonson Gu, Suwon, are weighted by each number of households, total population, maternal age group, child age group, old age group, Relief for the livelihood, and population/primary health clinics. We find that Kuwoon-Dong, Seodun-Dong, Seryu3-Dong, according the descending orders, are best sites which can minimize the weighted distance, and conclude that it is reasonable to determine the location of urban health sub-center among those sites.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.19 no.37
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• pp.263-269
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• 1996

The cost and customer service level of a logistics system depend primarily on the system design of the physical supply system and physical distribution system. The study presents the mathematical model and a huristic solution method of a combined location - vehicle routing problem(LVRP). In LVRP the objective is to determine the number and location of the distribution centers, the allocation of customers to distribution centers, and the vehicle delivery routes, so as to minimize the logistics total cost and satisfy the customer.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.14 no.23
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• pp.1-6
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• 1991

The physical distribution service(PDS) is essential to evaluate the business logistics system. The PDS combines the inventory service with the lead time to deliver. This paper is presented to model Mixed Zero-One integer programming which is to determine distribution center location and to allocation products, considering delivery lead time, from given candidate locations to given customer markets. A numerical example is given to demonstrate the applicability of Mixed Zero-One integer programming for Distribution-Location problem.

• ETRI Journal
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• v.5 no.3
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• pp.3-8
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• 1983

In the area of computer network planning, a location-allocation-size problem is involved. Since multi-facility location-allocation-size problems are very complex in formulating a mathematical model, it is a usual practise to adopt alternative approaches, which give no optimal results, instead of the optimal solution by mathematical approach. In this article, however, an attempt is made to formulate a mathematical model for the decision making problem of computer network design.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2005.10a
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• pp.38-50
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• 2005

The current Air defense missile, Nike, will be replaced by the Patriot missile in the near future. In this paper, we developed an optimal allocation model for the Patriot missile. In order to formulate the model, we applied a set covering and If model. This model considers not only weapon's characteristics and performances but also the threat of enemy aircrafts and SCUD missiles. When we apply this model, we can find the optimal location of Patriot batteries which maximizes the kill probability of enemy aircrafts and SCUD missiles attacking vital area of our forces. This model can directly be used to the decision making for the optimal military facility allocation.

• Journal of Korea Multimedia Society
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• v.16 no.7
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• pp.862-869
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• 2013

In order to support a cell-independent traffic asymmetry, the conventional TDD system cannot avoid crossed time slot (CTS) interference. Moreover, the TDD/FDD hierarchical overlay cellular systems is taken into account as a generally accepted cell model in a heterogeneous radio environment. In this paper, we propose an interference resolving radio resource allocation technique in a TDD-OFDMA cellular system that overlays a FDD-CDMA cell. In our proposed scheme, we exploit under-used FDD-CDMA uplink resource by TDD mobile abiding by a region based time slot(TS) allocation which in turn mitigates CTS interference considerably. It is demonstrated that combined with under-used resource utilization scheme based on mobile's location, the proposed technique can reduce CTS interference considerably and support the asymmetric traffic in TDD system.

• Journal of the Society of Disaster Information
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• v.18 no.1
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• pp.51-62
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• 2022

Purpose: This study analyzes accessibility of outdoor evacuation places for earthquake and the accessibility improvement effects when expanding the evacuation places in accessibility-deficient areas. In order to consider real-world evacuees, the accessibility analysis is based on service population not on resident population. Method: Location-allocation model as a GIS-based spatial optimization mode is used to analyze accessibility and vulnerable areas to evacuation places. Of location-allocation problem types, 'Maximize Coverage' method is chosen to allocate as many potential evacuees as possible to evacuation places. And impedence cutoffs or evacuation distances (times) are applied to three classes: 500m (7.5 minutes), 1,000m (15 minutes), and 1,500m (22.5 minutes). Case study area is Jung-gu areas, Seoul as a high-density downtown area. Result: Results show that accessibility-deficient areas and population to evacuation places are much more in service population than in resident population. Accessibility is significantly improved when increases when expanding the evacuation places in accessibility-deficient areas. Yet, accessibility-deficient areas are still remained since available lands are insufficient in the high-density downtown area. Conclusion: The study suggests that temporary evacuation facilities like outdoor evacuation places for earthquake need to consider real potential evacuees based not only on resident population but also on service population. Also, policy measures to provide emergency shelters need to more utilize spatial optimization tools like location-allocation model.