• Journal of the Korea Society for Simulation
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• v.23 no.4
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• pp.151-161
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• 2014

It is very important to evaluate proper acquisition of military aircraft against future threats in our military defense field. In previous studies, the evaluation has been determined in terms of tasking order or weapon power index. These methods compare the combat-effectiveness index and the number of aircraft. However, this study provides simulation analysis of proper quantity decision based on actual operational senarios of military aircraft using System Dynamics. The method reflects the properties of military aircraft operation concepts and considers the rate of failure of main systems on subsystems, as well as repair and crash rates caused by differentials in peacetime and wartime frame.

• Journal of the Korean Society of Food Culture
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• v.21 no.2
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• pp.154-160
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• 2006

This study examines the service satisfaction rate on high school students(637) in order to provide the basic data for marketing direction by analyzing the importance and satisfaction rate of the service quality. In IPA for the service quality, as the following properties are high in expectation as well as satisfaction they needed to maintain. They are the taste, scent, saltiness, proper temperature of the food, the quantity main food, nutritional value, the degree of freshness, and the smell of dining room. The following properties need the excessive efforts. They are the number of side dishes, eating place, the shape and material quality of dish, the costume of dining workers. As the following showed low importance degrees as well as satisfaction degrees, they don't need concentrated efforts. They are the harmony of color and shape, the interior design of the dining room, the arrangement of tables and chairs, the atmosphere of dining room, and the effect of nutrition instruction. As the education of nutrition is compulsory among the school group meal, the analysis based on the response of questioned students is supposed to be more careful. The items showing low satisfaction degrees while high importance degrees are considered to make an operational plans for the improvement through a variety of menu, the quality of food, the quantity for side-dishes, health control, the cleanness of dishes, the kindness of cooks, the performance of nutritionists, the charge of school meal, and meal time.

• Journal of the Korea Society for Simulation
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• v.31 no.4
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• pp.23-31
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• 2022

The development of innovative technology through the 4th Industrial Revolution is actively used in the defense field. In particular, surveillance and reconnaissance capabilities using drones will be of great help to the development of military combat capabilities, such as preparing for future military personnel reductions and reinforcing alert capabilities. In this study, we analyze the combat efficiency of drones how helpful drones can be to the military operations through simulations. Drones and enemy move in the efficient shortest path within a two-dimensional space in which operational areas are mapped into number such as detection probability. Based on the detection probability of an enemy infiltrating along the path with the lowest detection probability, the detection probability change that occurs whenever a drone is additionally deployed is presented, and we analyze the combat efficiency according to the additional drone input. Simulation proves that the increase in combat efficiency decreases as more drones are added in small operational areas such as company-level operational areas. This study is expected to contribute to the efficient operation of a limited number of drones in company-level units and to help determine the most desirable quantity of drones for additional combat power improvement.

• Steel and Composite Structures
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• v.27 no.3
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• pp.327-335
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• 2018

This paper presents structural assessment of a steel railway bridge for current condition using modal parameter to upgrade finite element modeling in order to gather accurate result. An adequate monitoring, such as acceleration, displacement, strain monitoring, is important tool to understand behavior and to assess structural performance of the structure under surround vibration by means of the dynamic analysis. Evaluation of conditions of an existing steel railway bridge consist of 4 decks, three of them are 14 m, one of them is 9.7 m, was performed with a numerical analysis and a series of dynamic tests. Numerical analysis was performed implementing finite element model of the bridge using SAP2000 software. Dynamic tests were performed by collecting acceleration data caused by surrounding vibrations and dynamic analysis is performed by Operational Modal Analysis (OMA) using collected acceleration data. The acceleration response of the steel bridge is assumed to be governing response quantity for structural assessment and provide valuable information about the current statute of the structure. Modal identification determined based on response of the structure play significant role for upgrading finite element model of the structure and helping structural evaluation. Numerical and experimental dynamic properties are compared and finite element model of the bridge is updated by changing of material properties to reduce the differences between the results. In this paper, an existing steel railway bridge with four spans is evaluated by finite element model improved using operational modal analysis. Structural analysis performed for the bridge both for original and calibrated models, and results are compared. It is demonstrated that differences in natural frequencies are reduced between 0.2% to 5% by calibrating finite element modeling and stiffness properties.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.1298-1302
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• 2011

The present study deals with the results of a thermo-fluid analysis applied to the cooling plate of the water cooling system developed for IGBT stacks, which was designed to keep the power semi-conductors from over heating problems. The cooling plate is to absorb a maximum quantity of 10kW from 4 IGBTs which are to be placed on both sides of the cooling plate, 2 IGBTs of them on each surface. For the analysis, Adina of CFD Program was used and an analysis was conducted to obtain the knowledges on heat and mass flow at both the plate and fluid flow inside. For the simulation, the operational conditions of a temperature difference of $15^{\circ}C$ for the working fluid and a uniform heat flux of about 92000 $W/m^2$ on the surface in contact with an IGBTs.

• Journal of Korean Institute of Industrial Engineers
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• v.24 no.1
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• pp.23-35
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• 1998

This article presents a network flow analysis to form flexible machine cells with minimum intercellular part moves and a neural network model to form part families. The operational sequences and production quantity of the part, and the number of cells and the cell size are taken into considerations for a 0-1 quadratic programming formulation and a network flow based solution procedure is developed. After designing the machine cells, a neural network approach for the integration of part families and the automatic assignment of new parts to the existing cells is proposed. A multi-layer backpropagation network with one hidden layer is used. Experimental results with varying number of neurons in hidden layer to evaluate the role of hidden neurons in the network learning performance are also presented. The comprehensive methodology developed in this article is appropriate for solving large-scale industrial applications without building the knowledge-based expert rule for the cellular manufacturing environment.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.36 no.6
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• pp.381-389
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• 1987

This paper presents a method for optimal load shedding in preserving a system security following abnormal condition as well as a sudden major supply outage. The method takes account of static characteristic of generators control and voltage and system frequency characteristic of loads. The optimization problem is solved by a gradient technique to get the maximal effect by the least quantity of load shedding considering line overloads as well as voltage disturbances and system frequency. The method is illustrated on a 8-bus system. It has been found that the use of the proposed algorithm for model systems alleviate the line overload more efficiently than the former method. It is believed that this method will be useful in security studies and operational planning.

• ETRI Journal
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• v.35 no.6
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• pp.1134-1143
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• 2013

The rising pace of technological change in information and communications technology (ICT) has provoked technological convergence by providing a new mode of diversification. This paper investigates the nature of ICT-based converging technologies by examining comparative empirical evidence on converging versus nonconverging technologies in relation to the following issues: patent application trends, concentration across technologies, the concentration of patenting activity across firms, R&D efforts, and a technology impact index. For this study, a new operational definition of ICT-based converging technology is derived, and a massive quantity of patents, up to around 600,000, is analyzed. This study follows the International Patent Classification as well as the modified European Commission's industry classification system for the classification of technologies and industries, respectively.

• Proceedings of the IEEK Conference
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• 2008.06a
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• pp.1163-1164
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• 2008

From the complexities and functional/operational expectations, the compositions of PC devices requires Device Drivers to deliver full performance of the Hardware. However, due to quick transition of hardwares and expectations of better performance of the system. As a rest users are exposed of unexpected failures of device drivers which will cause malfunction of the system which consequently cause damages in quantity as well as quality wise. In this paper, the method of calculation and/or forecast to unexpected failure will be suggested. It may not be the answer but can be a guide to calculation to economic damage due to device driver failure.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2003.05a
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• pp.999-1006
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• 2003

This research presents efficient operation schemes that is emphasized on mailing center's automation parts. We utilized the automation indicator to analyzed the mailing center system. For automation of the mailing center, we proposed the sorting automation alternative of registered mail, automation of conveyance system between workshops and the Up-Grade scheme for process improvement in mailing center. The selection of the registered mailing f s automation alternatives is composed of the AHP(Analytic Hierarchy Process) method. Through the analysis of the space and the quantity of materials, the simulation experiments are conducted to examine conveyance equipment possibility of the mailing center. By simplifying the mailing center conceptually, we proposed the upgrade of process for the mailing center system. The result of this research can give some ideas to people who are formulating a policy for the mailing center operation.