• Journal of the military operations research society of Korea
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• v.30 no.1
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• pp.135-152
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• 2004

Ever since Benoit's(1973, 1978) study, the relationship between defense spending and economic growth has been the subject of extensive empirical works. While a number of studies have reported that higher defense expenditure stimulate economic growth, many other studies have reported that an increase in military burden may hinder economic growth. To the extent that countries differ substantially in socioeconomic structures, the effects of defense spending cannot be generalized across countries. In this paper, Granger causality tests are performed between Korean defense expenditure and economic growth, consumption, investment, inflation and unemployment rate during the period from 1970 to 2002. The results show that Korean defense expenditure did not affect economic growth and unemployment rate. However, Korean defense expenditure caused consumption and inflation to decrease and investment to increase. On the other hand Korean defense expenditure was not Granger-caused by economic growth, consumption, investment, inflation and unemployment rate. In conclusion, the opportunity cost of Korean defense expenditure seemed to be relatively moderate considering Korean security environment. Even if it was not statistically significant, Korean defense burden at least did not bother economic growth.

• Journal of Electrical Engineering and Technology
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• v.6 no.1
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• pp.25-31
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• 2011

The purpose of power system maintenance is to prevent equipment failure. The maintenance strategy should be designed to balance costs and benefits because frequent maintenance increases cost while infrequent maintenance can also be costly due to electricity outages. This paper proposes maintenance modeling of a power distribution system using reliability centered maintenance (RCM). The proposed method includes comprehensive equipment modeling and impact analysis to evaluate the effect of equipment faults. The problem of finding the optimum maintenance strategy is formulated in terms of dynamic programming. The applied power system is based on the RBTS Bus 2 model, and the results demonstrate the potential for designing a maintenance strategy using the proposed model.

• Journal of Electrical Engineering and Technology
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• v.8 no.6
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• pp.1551-1558
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• 2013

$H_2$ design of decoupled control systems is treated in the generalized plant model. The existence condition of a decoupling controller is stated and a parameterized form of all achievable decoupled closed loop transfer matrices is presented by using the directional interpolation approaches under the assumption of simple transmission zeros. The class of all decoupling controllers that yield finite cost function is obtained as a parameterized form and an illustrative example to find the optimal controller is provided.

• Journal of Korean Society of Transportation
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• v.13 no.3
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• pp.19-33
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• 1995

Conventional traffic assignment techniques usually do not consider traveler's route choice behavior affected by hierachicla strucfture in urban highway system. This study realizes the route choice behavior such that travelers tend to choose more higher level of highway rather than lower level of highway for longer trops. Otherwise, for shorter trips, travelers tend to choose lower level of highway unless they can get sufficient travel time saving by using mojor arterial street or freeway (higher level of highway). Therefore, this study suggests a traffic assignment technique incorrporating route choice behavior related to hierachical highway structure by introducing some perception costs to generalized cost function such as perceptional preference measureemnt for higher level higheay and perceptional penalty when changing to different level of highway. Through simulation analysis, it is shown that the simulation results with the new traffic assignment echnique can be different a lot from the results with the convential method.

• Management Science and Financial Engineering
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• v.16 no.3
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• pp.95-102
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• 2010

This paper considers the robust inventory control problem introduced by Bertsimas and Thiele [4]. In their paper, they have shown that the robust version of the inventory control problem can be solved by solving a nominal inventory problem which is formulated as a mixed integer program. As a proper generalization of the model, we consider the problem with non-stationary cost. In this paper, we show that the generalized version can also be solved by solving a nominal inventory problem. Furthermore, we show that the problem can be solved efficiently.

• Proceedings of the KIEE Conference
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• 2008.04b
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• pp.3-5
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• 2008

In this paper, a modified diffusion model integrated with the effects of rebate programs is developed. The greater part of motors is included to various systems such as pump systems, fan systems, ventilation systems, motor itself, and so on. Hence, the existing rebate program is not suitable for these systems and a generalized rebate model for these systems is necessary. In the pre-study, a new diffusion model for motor rebate Program was proposed and the adequacy of this model was evaluated in the case of Korea. This paper shows that the motor rebate model could be applied to the case of pumps.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.5B no.1
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• pp.27-33
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• 2005

The development of modern high-energy magnet materials has allowed the replacement of field coils in many different types of electromagnetic energy conversion machines. As well, the linear synchronous motor has recently been proposed for linear motion with high efficiency and thrust. Thus, this paper presents an analytical solution for the high thrust and cost reduction of the Iron-Cored Permanent Magnet Linear Synchronous Motor (PMLSM) considering magnetization arrays and geometry. Hence, the superior utilization points in each of the magnetization arrays are provided by the height ratio of the magnet/air-gap and magnet/winding coil, etc. In formulation, the space harmonic method in analytical solutions and the generalized 2-D tensor finite element analysis can be used to evaluate force components in magneto static devices including the magnetostrictive phenomenon.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.21 no.48
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• pp.113-122
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• 1998

In this paper we consider the CSP requirements determination problem of new equipment(machine) system. For the newly procured equipment systems, mathematical analyses are made for the system which is constructed with the consumable parts to derive the associated CSP requirement determination model in mathematical expression. Based on these analyses, a mathematical model is derived for making an optimal CSP requirement determination subject to tile constraint of satisfying any given operational availability limitation. We assume that the failure of a part follows a Poisson process. Firstly, the operational availability concept in CSP is defined and the relation between the general system availability and the operational availability is established. Secondly, the problem is formulated as the cost minimization problem that should satisfy the operational availability limitation, and then, using the generalized Lagrange multipliers method, the optimal solution procedure is derived.

• Journal of Korean Society of Transportation
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• v.4 no.1
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• pp.41-71
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• 1986

본 연구는 $\ulcorner$네트웍$\lrcorner$ 평형모형을 이용하여 일반비용극수(Generalized Cost function)의 모형계수를 결정하는 하나의 방법을 제시한다. 이러한 기법은 동일모형을 실현 하기 위해서는 필연적인 과정이다. 기존의 대부분의 방법은 도시통행상 발생되는 통행자의 제비용을 직접 관측하고 수집하여 모형체계를 결정하였지만 본 연구에서는 이미 활용가능한 기종점별 통행실태조사를 이용하여 통행비용을 내생적으로 결정하고 이에 따른 모형체계를 추출한다. 따라서 본 연구는 자료수집상에 야기될 수 있는 제반 문제점의 행결과 동일목적 의 산출과정을 단순화시키고 내적일관성을 추구하였다는 데에 의의가 있다. 연구의 타당성 검토를 위해 $\ulcorner$시카고$\lrcorner$ 지역에 본 모형과 방법론을 적용하고 결과를 분석하였다.

• Journal of the Korea Society of Computer and Information
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• v.21 no.4
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• pp.89-96
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• 2016

In this paper, we study the relationship between vacancy duration and information items of a job posting by using generalized linear models and a decision tree analysis w.r.t. the three factors such as company characteristics, employment conditions, and constraints. The results indicate that the employment conditions rather than company characteristics are more influential to the vacancy duration. These effects are presumed to be based on the complex relations between the decisions of the employers and the job seekers. And in this paper we suggest the need to provide personalized and profiled labor market information tailored for a quick decision to job seekers and employers. Policy implication is that since employer's decision affects the vacation duration, employers may had better to provide a comprehensive labour market information including supply and demand of the required skills in order to reduce the time for judgment on the cost-effectiveness.