• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2018년도 추계학술대회
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• pp.351-353
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• 2018

본 연구에서는 분산 제어와 광 위상 공액이 적용된 링크에서 단일 모드 광섬유 길이와 중계 중간 당 잉여 분산 (RDPS; residual dispersion per span)의 크기가 랜덤하게 분포하는 분산 제어 링크에서 전반과 후반 전송 구획에서의 평균 RDPS 각기 다르게 갖는 경우의 파장 분할 다중 채널의 왜곡 보상 정보를 분석하였다.

• Journal of Mechanical Science and Technology
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• 제15권11호
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• pp.1482-1489
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• 2001

Thermally-induced errors originating from machine tool errors have received significant attention recently because high speed and precise machining is now the principal trend in manufacturing proce sses using CNC machine tools. Since the thermal error model is generally a function of temperature, the thermal error compensation system contains temperature sensors with the same number of temperature variables. The minimization of the number of variables in the thermal error model can affect the economical efficiency and the possibility of unexpected sensor fault in a error compensation system. This paper presents a thermal error model with minimum number of variables using a fuzzy logic strategy. The proposed method using a fuzzy logic strategy does not require any information about the characteristics of the plant contrary to numerical analysis techniques, but the developed thermal error model guarantees good prediction performance. The proposed modeling method can also be applied to any type of CNC machine tool if a combination of the possible input variables is determined because the error model parameters are only calculated mathematically-based on the number of temperature variables.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제53권8호
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• pp.500-508
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• 2004

This paper presents a new sensorless vector control system for high performance induction motor drives fed by a matrix converter with non-linearity compensation and disturbance observer. The nonlinear voltage distortion that is caused by commutation delay and on-state voltage drop in switching device is corrected by a new matrix converter modeling. The lumped disturbances such as parameter variation and load disturbance of the system are estimated by the radial basis function network (RBFN). An adaptive observer is also employed to bring better responses at the low speed operation. Experimental results are shown to illustrate the performance of the proposed system.

• 전기학회논문지
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• 제64권5호
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• pp.661-666
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• 2015

This paper proposes a method for solving running cost problem by minimizing switching reactive power compensation devices. An objective function was modeled by calculating the weighting value of cost, and a solution was derived using ILP. This paper suggests optimal coordinative control method between FACTS, Shunt Reactors, Capacitors and OLTC. Therefore, it is valuable for decision maker in determining order and capacity of devices which gaining a voltage stabilization. As a result, the objectives of voltage stabilization and cost minimization were achieved simultaneously. This realizes the economic efficiency of the system. We start by showing how to solve systems of linear equations using the language of pivots and tableaus. The effectiveness of this technique is demonstrated in modified PSS/E MIGUM 45 bus system. The simulation results show the effectiveness of this algorithm by comparing the outcome withseveral established methods.

• Journal of Electrical Engineering and Technology
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• 제6권5호
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• pp.647-657
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• 2011

The present paper proposes a sliding mode control with fixed switching frequency for three-phase three-leg voltage source inverter based four-wire shunt active power filter. The aim is to improve phase current waveform, neutral current mitigation, and reactive power compensation in electric power distribution system. The performed sliding mode for active filter current control is formulated using elementary differential geometry. The discrete control vector is deduced from the sliding surface accessibility using the Lyapunov stability. The problem of the switching frequency is addressed by considering hysteresis comparators for the switched signals generation. Through this method, a variable hysteresis band has been established as a function of the sliding mode equivalent control and a predefined switching frequency in order to keep this band constant. The proposed control has been verified with computer simulation which showed satisfactory results.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2012년도 전력전자학술대회 논문집
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• pp.150-151
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• 2012

The utility grid has a supply of electric energy which is larger than the usually required power consumption under peak load condition. So, power distribution is required to have a heavy capacity because of peak-load period. To solve the problem, this paper proposes a 10kW rapid charger system which has a function of load compensation at the peak-load condition. The proposed system supplies power demanded by peak-load through transferring energy in the battery of electric vehicle to the grid. V2G operation is verified through simulation performed by 10kW rapid-charger.

• 소성∙가공
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• 제13권7호
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• pp.594-599
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• 2004

In the sheet metal forming operations, the strain measurement of sheet panel is an essential work which provides the formability information needed in die design, process design, and product inspection. To measure efficiently complex geometry strains, the 3-dimensional automative strain measurement system, which theoretically has a high accuracy but practically has about 3～5％ strain error, is often used. For eliminating the strain error resulted in measuring the strains of formed panels using an automated strain measurement system, the position error calibration method is suggested, which computes accurate strains using the grids with accurate nodal coordinates. The accurate nodal coordinates are calculated by adding the nodal coordinates measured by the measurement system and the position error found using the multiple regression method as a function of the main error parameters obtained from the analysis of strain error in a standard cube. For the verification, the strain distributions of square and dome cups obtained from the position error calibration method are compared with those provided by the finite element analysis and ASAME.

• 한국군사과학기술학회지
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• 제22권2호
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• pp.233-240
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• 2019

High-altitude ElectroMagnetic Pulse(HEMP) is a high-power electromagnetic pulse caused by nuclear explosions at altitudes above 30 km. This pulse can cause serious damage to the electrical/electronic device. Therefore, there are a lot of studies on the effects of HEMP in the literature. When conducting studies on the effects of HEMP, it is essential to measure the simulated HEMP. Depending on the need for measurement, this paper focuses on the HEMP measurement method. This paper proposes a measurement method using frequency domain compensation to extract the correct waveform and solves the offset problem more efficiently than the conventional methods. The proposed method is verified by experiment using HEMP simulator and measurement system in ADD.

• 한국병원경영학회지
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• 제19권3호
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• pp.29-42
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• 2014

This study included empirical methods of study such as surveys and interviews with military hospital administrators from 14 military hospitals across the country. The results of the study is described below. First, results by demographic characteristics show that higher level of organizational commitment was found in males than females and in singles than married couples. Also, by organizational units, major units of military hospitals showed higher level of organizational commitment as well as job satisfaction. Second, Fair compensation had positive(+) effects on the study participants' job satisfaction and organizational commitment as the research hypothesized. Compensation included monetary and social benefits for the work performed. A transparent compensation system to reward members that performed the best for the department and the corps with appropriate amounts must be in place. Third, the organization culture of being considerate had positive(+) effects on job satisfaction and organizational commitment while the culture of giving commands had negative(-) effects. Fourth, Conflict factors had negative(-) effects on job satisfaction with no direct effect on organizational commitment. Any organization must take measures when adverse effects of conflicts surface. As shown by the analysis results, conflict factors bring negative results to job satisfaction and organizational commitments. Department managers should utilize the proper function of conflicts as an accelerator in organization operation.

• 전력전자학회논문지
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• 제9권3호
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• pp.275-284
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• 2004

본 논문은 동적전압보상기(DVR)의 제어를 위한 우수한 성능의 디지털제어기를 제시하고 제어이득(Control Gain)의 설정에 관하여 논한다. DVR계통의 전력회로를 분석하여 DVR의 운전한계를 찾고 그에 따른 제어목표 및 제어기 구조를 제시한다. 디지털 제어기는 인버터의 PWM 스위칭과 함께 제어시스템의 시간지연을 야기한다. 이러한 시간 지연은 제어시스템의 전달함수를 1차수 높게 하여 제어시스템을 더한층 복잡하고 불안정하게 한다. 본 논문은 제어기의 시간지연을 고려하여 제안된 제어기의 이득을 설정하는 방법을 제시하고 인버터의 스위칭 주파수와 관련하여 출력측 필터요소의 설계지침을 제시한다. 제안된 설계방법에 의하여 전디지털화(Full Digital Control) 된 DVR 시스템을 제작하여 이론을 검증한다.