• 드라이브 ㆍ 컨트롤
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• 제15권3호
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• pp.14-20
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• 2018

Wet clutches in an automatic transmission enable the transmission of the engine power by the frictional torque experienced and noted between disk and plates. Since the clutch frictional torque considerably affects the shift quality of an automatic transmission as well as the durability of the machinery, its friction characteristics must be carefully examined to meet the design requirements. The SAE No. 2 friction test machine is a well-known standard to evaluate mainly the friction characteristics of plate clutches along with the required automatic transmission fluids. This paper reviews the experimental analysis of the wet clutch friction characteristics by using the exclusively developed clutch test machine which is capable of controlling the clutch test procedure, in accordance with the applicable test standard and processing of the experimental data automatically. As the clutch test machine is designed for the accommodation of dual clutches which is applied to the real transmission, it can evaluate not only the clutch friction characteristics, but also an actuation performance of a measured clutch piston. In respect to friction characteristics involving dynamic friction coefficients, the energy absorbed in a clutch disk and the recorded temperatures of clutch plates during braking actions and procedures are also investigated. Additionally, the change of friction coefficients by the use of the repeated clutch application is also observed with the endurance test functions of an accurately calibrated and dedicated clutch test machine.

• 전기학회논문지
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• 제63권10호
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• pp.1364-1370
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• 2014

Power system fault analysis has been based on symmetrical component method, which describes power system elements by positive, negative and zero sequence impedance. Obtaining accurate line impedances as possible are very important for estimating fault current magnitude and setting distance relay accurately. Especially, accurate calculation of zero sequence impedance is important because most of transmission line faults are line-to-ground faults, not balanced three-phase fault. Since KEPCO has started measuring of transmission line impedance at 2005, it has been revealed that the measured and calculated line impedances are well agreed within reasonable accuracy. In case of underground transmission lines, however, large discrepancies in zero sequence impedance were observed occasionally. Since zero sequence impedance is an important input data for distance relay to locate faulted point correctly, it is urgently required to analyze, detect and consider countermeasures to the source of these discrepancies. In this paper, development of pre/post processor to ATP (Alternative Transient Program) version of EMTP (Electro-Magnetic Transient Program) for sequence impedance calculation was described. With the developed processor ATP-cable, effects of ground resistance and ECC (Earth Continuity Conductor) on sequence impedance were analyzed.

• 대한교통학회지
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• 제17권4호
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• pp.71-84
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• 1999

본 연구의 목적은 기존 동적통행배정모형의 접근 기법과는 달리 교통류이론을 이용하여 동적분석모형을 구축하고, 이 모형에 적합한 동적통행배정기법을 개발하는 것이다. 본 연구에서는 기존 동적교통류 모델 중 동적통행배정에 가장 적합하다고 판단되는 Daganzo의 cell transmission theory를 이용하여 동적분석모형을 구축하였으며, 동적통행배정기법인 분류부분할모델, 비용갱신모듈, 링크비용함수모듈을 새롭게 개발하였다. 또한 Daganzo가 명확하게 제시하지 않은 최대대기시간 결정 알고리듬을 제시하였다. 본 연구에서 구축한 모형을 가상의 네트워크에 적용한 결과 병목구간분석, HOV타로 효과분석등은 교통특성을 현실적으로 반영하고 있다. 통행배정결과는 수학적 기법을 적용한 동적통행배정모형과 같이 완전한 균형(equibriun)상태의 해를 보여주지 못하지만, 노선별 평균통행시간이 시간대별로 비슷하게 유지해나가는 결과를 보이고 있다. 본 모형은 고속도로 합류부 및 분류부의 교통특성분석, HOV 효과분석, TCS 및 램프미터링과 접목하여 고속도로 운영에 이용될 수 있으리라 판단된다.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2008년도 춘계학술대회논문집
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• pp.80-83
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• 2008

The characteristics of the spread of a forest fire are generally related to the attributes of combustibles, geographical features, and meteorological conditions, such as wind conditions. The most common methodology used to create a prediction model for the spread of forest fires, based on the numerical analysis of the development stages of a forest fire, is an analysis of heat energy transmission by the stage of heat transmission. When a forest fire breaks out, the analysis of the transmission velocity of heat energy is quantifiable by the spread velocity of flame movement through a physical and chemical analysis at every stage of the fire development from flame production and heat transmission to its termination. In this study, the formula used for the 1-dimensional surface forest fire behavior prediction model, derived from a numerical analysis of the surface flame spread rate of solid combustibles, is introduced. The formula for the 1-dimensional surface forest fire behavior prediction model is the estimated equation of the flame spread velocity, depending on the condition of wind velocity on the ground. Experimental and theoretical equations on flame duration, flame height, flame temperature, ignition temperature of surface fuels, etc., has been applied to the device of this formula. As a result of a comparison between the ROS(rate of spread) from this formula and ROSs from various equations of other models or experimental values, a trend suggesting an increasing curved line of the exponent function under 3m/s or less wind velocity condition was identified. As a result of a comparison between experimental values and numerically analyzed values for fallen pine tree leaves, the flame spread velocity reveals has a error of less than 20%.

• 한국의류학회지
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• 제38권5호
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• pp.690-704
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• 2014

This study examined the risk perception in internet shopping by Chinese and analyzed the effects of risk perception on internet word-of-mouth acceptance and transmission. This analysis was conducted with data collected from 373 Chinese individuals in their 20s. Data were analyzed with factorial analysis, cluster analysis, ANOVA, multiple regression analysis, Chi-square test, and Cronbach's ${\alpha}$ using SPSS 18.0. The results were: 1) The factor analysis of risk perception extracted four factors: fashion/social psychological risk, product risk, transaction risk, and economic risk. The cluster analysis classified them into: Group with low-risk, Group with high-risk, Group with economic risk, and Group with medium-risk. 2) Group with high-risk and Group with economic risk had a higher word-of-mouth acceptance than other groups. The Group with a high-risk had more word-of-mouth transmission than other groups. 3) It was found that when word-of-mouth was accepted, the factual information about fashion products (size and material) was most referred to, and that the overall evaluation of satisfaction and dissatisfaction was most conveyed when word-of-mouth was conveyed. 4) Internet word-of-mouth acceptance was affected by product risk, economic risk, and transaction risk. Internet word-of-mouth transmission was affected by economic risk, and fashion/social psychological risk, product risk, and transaction risk.

• 전기학회논문지
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• 제61권2호
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• pp.187-193
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• 2012

Nash Equilibrium (NE) is as useful tool for investigating a participant's strategic generation quantity in a competitive electricity market. Cournot model may give a mixed strategy NE instead of a pure strategy when transmission constraints are considered. A mixed strategy is difficult to compute, complicated to understand conceptually, and hard to implement in an electricity market practically. This paper presents that a mixed strategy does not appear in Stackelberg leader-follower model even under a transmission congestion. A solution method is proposed for the leader-follower model under a nondifferentiable space of a strategy variable. Based on the pure strategy NE with a transmission line congested, the merit of leader-follower model is shown from a social welfare point of view.

• 한국해양공학회지
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• 제23권3호
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• pp.6-13
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• 2009

Based on the boundary element method, the motion responses and transmission coefficients of a moored floating breakwater were investigated in oblique waves. To satisfy the outgoing radiation condition in the far field, the fluid domain was divided into inner and outer regions. The complete solution could be obtained by applying the matching conditions between the eigenfunction-based outer solution and BEM-based inner solution. Using the developed predictive tools, the wave exciting forces, added mass, damping coefficients, motion responses, and transmission coefficients were assessed for various combinations of breakwater configuration, wave heading, mooring cables properties, and wave characteristics. It was found that the transmission coefficient for a moored floating breakwater was closely dependent on the motion responses, which were greatly amplified at the resonant frequencies.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 춘계학술대회논문집
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• pp.625-628
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• 2005

Silencers are extensively used for reducing noise in an exhaust system of internal combustion Engine and fluid machineries. The prediction and measurement of the transmission loss as the acoustic performance of silencers are important in early design stage. In the measurement of transmission loss, the semi-anechoic terminations are general used for reducing unwanted effects by reflecting wave. However it is very hard to remove reflecting wave perfectly. So the research about the error made by reflecting wave is important. The analysis about errors made by reflections and modification techniques are proposed. For an application example, the diesel particulate filter (DPF) is chosen. The transmission loss of DPF is measured with and without considerations of reflecting wave.

• 한국정보통신학회논문지
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• 제15권4호
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• pp.930-934
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• 2011

통신시스템에 사용되는 프로세서는 여러 로직이 사용되는데 본 연구에서는, 입력과 출력 사이에 정확하게 상호 정보를 전달하기 위해, SSTL2-II 2.5V 로직을 이용하여 전송 선로의 길이 변화와 데이터 속도의 변화 시 발생되는 데이터 전송특성을 살펴보았다. 전송 선로의 길이가 30cm이고 데이터 속도가 400Mbps일 경우 안정된 특성을 얻었다.

• 한국정밀공학회지
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• 제27권11호
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• pp.57-62
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• 2010

The transmission case has bearing loads, The case should be designed with more stiffness and lightweight under high external loads, In this study, we performed FEA(Finite Element Analysis) for the transmission case and performed topology optimization base on the results of FEA. We performed topology optimization with the control of the shape size which is the results of topology optimization and suggested the shaped of the transmission case of topology optimization.