• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.6
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• pp.2739-2746
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• 2011

This paper proposes the method for more effectively calculating X/R which is the ratio of equivalent reactance(X) and resistance(R) of the bulk power system and analyses the characteristic of X/R values by applying the proposed method to the real bulk power systems. X/R is used to determine the rating of the relay in the bulk power systems and its value has been accepted to be big enough to ignore the equivalent resistance of the bulk power systems. However, X/R is calculated as a big number when only the upper transformer and transmission line are considered. The correct approach to calculating X/R needs to consider all the parameters including generators, transformers, lines and loads. This paper calculates X/R of the bulk power systems using dynamic models which have been used to analyse the power system stability. The effectiveness of the proposed method is verified by applying it to the test system and X/R values of the real bulk power systems are analyzed. In addition, the dependence of X/R on the closeness of its calculating locations to the generator is verified by using the marginal loss factor which has been used in the electricity market.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.8
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• pp.235-240
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• 2020

This study evaluated the improvements for circuits of a combat vehicle distribution box to reduce the noise generated in electromagnetic compatibility (EMC) testing. An analysis of the distribution boxes that failed the standard revealed the conducted noise generated from the converter and semiconductor switching elements on the circuit board. The distribution box transfers power from the generator and battery to the cooling system of a combat vehicle to keep turning the air conditioner on and off. Two methods were proposed to overcome this problem: a passive filter was added to the circuit board for the first method, and the converter and switching elements were replaced with the relays for the second method. Both methods were effective in reducing noise, but a greater improvement was obtained from the second method. The second method was applied to a combat vehicle system and was found to be suitable according to the EMC standards.

• Journal of Korean Society of Environmental Engineers
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• v.37 no.2
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• pp.126-135
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• 2015

Increase of delivery effect of pollutant loads and surface runoff due to urbanization of catchment area results in serious environmental problems in receiving urban streams. This study aims to develop integrated stormwater management system to assist efficient urban stream flow and water quality control using information from the Storm Water Management Model (SWMM), real time water level and quality monitoring system and remote or automatic treatment facility control system. Based on field observations in the study site, most of the pollutant loads are flushed within 4 hours of the rainfall event. SWMM simulation results indicates that the treatment system can store up to 6 mm of cumulative rainfall in the study catchment area, and this means any type of normal rainfall situation can be treated using the system. Relationship between rainfall amount and fill time were developed for various rainfall duration for operation of stormwater treatment system in this study. This study can further provide inputs of river water quality model and thus can effectively assist integrated water resources management in urban catchment and streams.

• Korean Chemical Engineering Research
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• v.54 no.3
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• pp.305-309
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• 2016

Recently, there are many efforts focused on development of more economical non-fluorinated membranes for PEMFCs (Proton Exchange Membrane Fuel Cells). In this study, to test the durability of sPEEK MEA (Membrane and Electrode Assembly), ADT (Accelerated Degradation Test) of MEA degradation was done at the condition that membrane and electrode were degraded simultaneously. Before and after degradation, I-V polarization curve, hydrogen crossover, electrochemical surface area, membrane resistance and charge transfer resistance were measured. Although the permeability of hydrogen through sPEEK membrane was low, sPEEK membrane was weaker to radical evolved at low humidity and OCV condition than fluorinated membrane such as Nafion. Performance after MEA degradation for 144 hours and 271 hours were reduced by 15% and 65%, respectively. It was showed that the main cause of rapid decrease of performance after 144 hours was shorting due to Pt/C particles in the pinholes.

• Journal of Forest and Environmental Science
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• v.17 no.1
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• pp.29-36
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• 2001

Compared to other industries, pulp and paper industry use a lot of water. As a result, a large amount of the waste water is discharged in the pulp and paper industry. This study was investigated to prevent the environmental pollution terribly faced with our society nowadays. In the waste water of pulp and paper, there are so many things in the waste water, like fiber, filler, and other organic solvent etc. so we must remove them from our environment. This study was investigated to experiment on test of impressed filtration with the kind and quantity of coagulant and the variance of pressure. In this study, we used feds, alums. $CaCl_2$, polymer as a coagulant and these pressure was 49, 98, 147, 196kpa. According to this study, we measured the speed of filtration and turbidity, measuring filtrated water. According to the values, we know the fact that as the consistency of coagulant and pressure were high, the filtration was good.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.25 no.3
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• pp.259-268
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• 2014

In this paper, we suggest a method of extracting circuit parameters of the insulating transformer using S-parameter measurement, especially in high frequency range. At 60 Hz, conventionally, no load test and short circuit test are used to extract the circuit parameters. In this paper S-parameters measured from VNA(Vector Network Analyzer) were used to extract the transformer parameters using data fitting method (optimization). The S-parameters from the equivalent circuit using the extracted parameters showed good agreement with those from measurement. Furthermore, the transformer secondary voltages from the equivalent circuit model also coincide quite exactly to the measured secondary voltages in sinusoidal forms. Finally we assert that the proposed method to extract the parameters for the insulating transformer using S-parameter is valid especially in high frequency.

• Journal of Korean Tunnelling and Underground Space Association
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• v.17 no.4
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• pp.473-485
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• 2015

The problems for non-rotating of a disc cutter proceed from the faults in inner parts of the disc cutter such as the leak of hydraulic fluid, the intrusion of tunnel mucks and water, overloading, overheating, poor assembly and substandard material. The rotating of a disc cutter is an indicator to show that the inner parts of disc cutter is operable, although the rotational torque depends on the extent of the damage. Therefore, the key in the problems for non-rotating of disc cutter is to maintain that the tapered roller bearings are working properly. This study aims to investigate the inner parts disassembled from disc cutters applied to the field tests in order to help decision for reuse of the disc cutters. As results, surface finishing to remove the scratch on the load zone of the hubs is needed, with the intent to reuse a hub. And the investigation of lapping surface by optical microscope of floating seals and the contamination test of oil need to be performed for reuse of a disc cutter. Especially, the analysis results show that the floating seals play a key role in the normal operation of bearings. There is nothing significant to report in the rest parts such as bearing, shaft, seal retainers.

• Journal of the Korea Society of Computer and Information
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• v.16 no.9
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• pp.185-192
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• 2011

The purpose of this paper is to propose the design and implementation of a korean style internet-based test system on the basis of efficiency and stability for middle server. The current assessment system has some unstable elements with regard to transmission procedure, cost, system load and stability. This paper proposes a series of activities for the performance improvement of korean style internet-based test system which finally produced various excellent results in the administration of expense control, human resources, and special operational affairs. The proposed system's technological factors using middle server have been tested through a basic simulation pilot system. Actual development procedure starts from the analysis required by improving the shortcomings of existing internet-based test systems. A efficiency comparison with existing system and newly developed system was made in the area of number of operators, abnormal processing, system maintenances. Korean style internet-based test system using middle server has shown great efficiency increased to the maximum of 2 times about the effectiveness of processing for various parts. The korean style internet-based test system using middle server have been given good evaluations with regard to the convenience of their use and the management system for operators and supervisors.

• Proceedings of the Korea Inteligent Information System Society Conference
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• 2002.11a
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• pp.379-384
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• 2002

개발적인 측면에서 온라인 게임 환경에서의 NPC(Non Playable Character)들은 환경인식능력, 이동능력, 특수 능력 및 아이템의 소유 배분 등을 원활히 하기 위한 능력들을 소유해야 하며, 게임 환경을 인식, 저장하기 위한 데이터구조와 자신만의 독특한 임무(mission)를 달성하기 위한 계획을 갖고 행위를 해야 한다. 이런 의미에서 NPC는 자신만의 고유한 규칙과 행동 패턴, 그리고 목표(Goal)와 이를 실행하기 위한 계획(plan)을 소유하는 에이전트로 인식되어야 할 것이다. 그러나, 기존 게임의 NPC 제어 구조나 구현 방법은 이러한 요구조건에 부합되지 못한 부분이 많았다. C/C++ 같은 컴퓨터 언어들을 이용한 구현은 NPC의 유연성이나, 행위에 많은 문제점이 있었다. 이들 언어의 switch 문법은 NPC의 몇몇 특정 상태를 묘사하고, 그에 대한 행위를 지정하는 방법으로 사용되었으나, 게임 환경이 복잡해지면서, 더욱더 방대한 코드를 만들어야 했고, 해석하는데 많은 어려움을 주었으며, 동일한 NPC에 다른 행동패턴을 적용시키기도 어려웠다. 또한, 대부분의 제어권을 게임 서버 폭에서 도맡아 함으로써, 서버측에 많은 과부하 요인이 되기도 하였다. 이러한 어려움을 제거하기 위해서 게임 스크립트를 사용하기도 하였지만, 그 또한 단순 반복적인 패턴에 사용되거나, 캐릭터의 속성적인 측면만을 기술 할 수 있을 뿐이었다 이러한 어려움을 해소하기 위해서는 NPC들의 작업에 필요한 지식의 계층적 분화를 해야 하고, 현재 상황과 목표 변화에 적합한 반응을 표현할 수 있는 스크립트의 개발이 필수 적이라 할 수 있다 또한 스크립트의 실행도 게임 서버 측이 아닌 클라이언트 측에서 수행됨으로써, 서버에 걸리는 많은 부하를 줄일 수 있어야 할 것이다. 본 논문에서는, 대표적인 반응형 에이전트 시스템인 UMPRS/JAM을 이용하여, 에이전트 기반의 게임 캐릭터 구현 방법론에 대해 알아본다.퓨터 부품조립을 사용해서 Template-based reasoning 예를 보인다 본 방법론은 검색노력을 줄이고, 검색에 있어 Feasibility와 Admissibility를 보장한다.매김할 수 있는 중요한 계기가 될 것이다.재무/비재무적 지표를 고려한 인공신경망기법의 예측적중률이 높은 것으로 나타났다. 즉, 로지스틱회귀 분석의 재무적 지표모형은 훈련, 시험용이 84.45%, 85.10%인 반면, 재무/비재무적 지표모형은 84.45%, 85.08%로서 거의 동일한 예측적중률을 가졌으나 인공신경망기법 분석에서는 재무적 지표모형이 92.23%, 85.10%인 반면, 재무/비재무적 지표모형에서는 91.12%, 88.06%로서 향상된 예측적중률을 나타내었다.ting LMS according to increasing the step-size parameter $\mu$ in the experimentally computed. learning curve. Also we find that convergence speed of proposed algorithm is increased by (B+1) time proportional to B which B is the number of recycled data buffer without complexity of computation. Adaptive transversal filter with proposed data recycling buffer algorithm could efficiently reject ISI of channel and increase speed of convergence in avoidance burden of computational complexity in reality when it was experimented having

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.10
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• pp.174-180
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• 2020

This paper presents the development of a tacho generator that is applicable to a DC motor for anti-aircraft weapon systems. In general, devices such as tacho generators and resolvers are used as feedback devices for controlling DC motors. A tacho generator with a wide operating temperature range was developed, which has robust characteristics against shock loads and vibrations according to the operational characteristics of anti-aircraft weapon systems. The target specifications were set based on the requirements of the tacho generator currently in operation. A rotor coupled to the shaft of the motor and a stator coupled to the housing of the motor were then designed and manufactured. The inductance was 31.0 mH, the terminal resistance was 147.7 ohms, and the rotational measurement factor was satisfactory under both normal operation and operating conditions after the maximum speed for the standard of 9.500 ± 0.475 V/krpm. In addition, the environmental suitability of the applied equipment was confirmed through the rate of change in unit temperature, and it was found that the temperature characteristics were all within 0.03 %/℃.