• Journal of Korean Institute of Industrial Engineers
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• v.23 no.2
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• pp.385-401
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• 1997

In this paper, we evaluate the performance of zone-based registration and distance-based registration. First, we propose the mobility model which can be used to analyze the performance of both zone-based registration and distance-based registration. And using the proposed mobility model, we obtain several performance measures and perform numerical computation to compare the performance of two registration methods. Numerical results show that in general zone-based registration needs less number of registration than distance-based registration. On the other hand, if distance-based registration is used, registration load is equally distributed to all cells in a location area and ping-pong phenomenon is not occurred. And when a VLR area is composed of a few location areas, distance-based registration may need less registration load than zone-based registration. Therefore, a proper registration method should be selected considering system circumstances and implementation complexity, and the selected method should be implemented so as to change system parameters according to system circumstances.

• Industrial Engineering and Management Systems
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• v.8 no.1
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• pp.29-36
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• 2009

We present two local-search based metaheuristics for the multi-source capacitated facility location problem. In such a problem, each customer's demand can be supplied by one or more facilities. The problem is NP-hard and the number of locations in the optimal solution is unknown. To keep the search process effective, the proposed methods adopt the following features: (1) a multi-exchange neighborhood structure, (2) a tabu list that keeps track of recently visited solutions, and (3) a multi-start to enhance the diversified search paths. The transportation simplex method is applied in an efficient manner to obtain the optimal solutions to neighbors of the current solution under the algorithm framework. Two in-and-out selection rules are also proposed in the algorithms with the purpose of finding promising solutions in a short computational time. Our computational results for some of the benchmark instances, as well as some instances generated using a method in the literature, have demonstrated the effectiveness of this approach.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.10a
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• pp.186-189
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• 2015

최근 GPS가 탑재된 스마트폰의 보급이 늘어나면서 위치 기반 서비스가 빠르게 성장해 왔다. 위치조회의 방법은 크게 GPS를 이용한 위치 조회 서비스, 네트워크 위치 조회 서비스, 하이브리드 위치조회 서비스가 있다. 사용자 또는 제 3자가 위치 조회를 요청하였을 경우 사용자의 스마트폰에 장착된 소형 GPS 모듈을 조회하여 제공하여 준다. 하지만 GPS 모듈의 경우 실내에서는 취약하므로 만약 조회한 스마트폰의 위치가 실내에 있다면 Wi-Fi, 모바일 네트워크를 이용하여 위치를 조회하여 제공한다. 본 논문에서는 GPS 기반 위치 조회, 네트워크 기반 위치 조회, 하이브리드 위치 조회를 소개 및 비교 분석한다.

• Proceedings of the KIEE Conference
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• 1998.07c
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• pp.1063-1065
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• 1998

This paper discusses the selection of optimal location of Thyristor Controlled Series Compensator (TCSC) devices to maintain the steady-state voltage profile within limits. A procedure for selecting optimal TCSC location based on sensitivity analysis is developed. This approach identifies the critical lines by evaluating all the voltage magnitudes sensitivity with respect to a line reactance. Computer simulation of a example system is used to verify the proposed procedure.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.22 no.2
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• pp.97-103
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• 2010

For large reciprocating compressors in parallel operation, an analytical study has been carried out on the gas pulsation in associated discharge piping lines. Since the pressure pulsation at a valve, valve dynamics, and the gas flow rate through the valve are interrelated, affecting one another, these need to be solved simultaneously. Acoustic transfer matrix method, which relates acoustic pressure and velocity at one location to those at another location, has been adopted to calculate the effect of the gas flow at one valve location on the gas pulsation at other valve locations.

• Journal of the Korea Safety Management & Science
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• v.7 no.5
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• pp.97-105
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• 2005

Achievement degree can be improved by display offering more effective process about cognitive, pattern recognition than making observers use memory, integration, and cognitive process of control. And this research is proved by several scholars' researches [4][5][7][9]. In this study, researches was conducted about cognition according to layout of object in instrument panel. To decide layout of instrument panel, Cognition value was preferentially decided about all location. And then, objects are arranged to correct position of low cognition following the inferior procedure about each location. As a result, we get conclusion that gauge location is taken in high importance order through mechanical importance degree bringing huge damage during driving forklift-truck.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.6
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• pp.131-138
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• 2004

The objective of this paper is to decide optimal location of a pin-hole to minimize stress concentration around the hole in a rotating disc. The focus of this investigation is to evaluate the effect of pin-hole on stress distribution around the hole using optimum design technique and finite element analysis. Design variables are the radial and the angular location of pin-hole from center of the hole and objective function is the maximum stress around hole in a rotating disc. Using first order method of optimization technique, we found that the maximum equivalent stress around the hole with optimized pin-hole could be reduced by 15.1% compared to that without pin-hole.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.11 no.6
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• pp.169-174
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• 2001

Optimization of the collocated piezoceramic sensor/actuator placement is investigated numerically and verified experimentally for vibration control of laminated composite plates. The finite element method is used for the analysis of dynamic characteristics of the laminated composite plates with the piezoceramic sensor/actuator. The structural damping index(SDI) is defined from the modal damping(2$\omega$ζ) . It is chosen as the objective function for optimization. Weights for each vibrational mode are taken into account in the SDI calculation. The gradient method is used for the optimization. Optimum location of the piezoceramic sensor/actuator is determined by maximizing the SDI. Numerical simulation and experimental results show that the optimum location of the piezoceramic sensor/actuator is dependent upon the outer layer fiber orientations of the plate, and location and size of the piezoceramic sensor/actuator.

• Journal of Korea Society of Industrial Information Systems
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• v.11 no.2
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• pp.1-8
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• 2006

In this paper, we propose a distance-based location registration scheme and evaluate it's performance in a mobility model. We compare performance of the distance-based registration scheme to that of zone-based registration scheme at the mobility model. Numerical results show that the registration load of the distance-based registration with call arrival is similar to that of the zone-based registration, and is equally distributed to all cells in a location area. So the proposed scheme can be effectively used in the limited radio resources.

• Smart Structures and Systems
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• v.16 no.1
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• pp.213-222
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• 2015

Early detection and precise location of leakage is of great importance for life-cycle maintenance and management of municipal pipeline system. In the past few years, acoustic emission (AE) techniques have demonstrated to be an excellent tool for on-line leakage detection. Regarding the multi-mode and frequency dispersion characteristics of AE signals propagating along a pipeline, the direct cross-correlation technique that assumes the constant AE propagation velocity does not perform well in practice for acoustic leak location. This paper presents an improved cross-correlation method based on wavelet transform, with due consideration of the frequency dispersion characteristics of AE wave and the contribution of different mode. Laboratory experiments conducted to simulate pipeline gas leakage and investigate the frequency spectrum signatures of AE leak signals. By comparing with the other methods for leak location identification, the feasibility and superiority of the proposed method are verified.