• 전기학회논문지
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• 제56권3호
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• pp.465-471
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• 2007

The one step type pole and two step type pole are used in KEPCO's distribution system. The neutral current increases in three-phase four-wire distribution system due to unbalanced load. Usually, power line and communication line are installed at contiguity by effect of topography in Korea. To this end, the damages such as electrostatic induction, electromagnetic induction and harmonic induction generated by induced voltage and current are occured in power line and communication line. This paper calculates the neutral current in KEPCO's distribution system using EMTP by composing various simulated conditions. Also, these results are verified by vector analysis.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제48권11호
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• pp.597-603
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• 1999

Due to its simple construction, operation steadiness and low cost, claw pole step motor is widely used for OA machine and automobile. This paper deals with analysis fo claw pole motor, especially eyeing to dynamic characteristics. To analyze dynamic characteristics of claw pole step motor, torque development in each angular step of rotor are surveyed and torque equation is drived using permeance method. To adopt the airgap MMF, the magnetic equivalent circuit of the motor is introduced. On the base of the magnetic equivalent circuit, the air gap flux equation is derived. To get a optimum design of the motor, the torque characteristic is studied in variation of coil data and remanence value of permanent magnetic material.

• 대한전자공학회논문지TC
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• 제45권12호
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• pp.146-151
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• 2008

Suspended Strip Line의 Open End와 Step 불연속 효과의 등가회로를 구하였다. 각 불연속 효과를 표현하는 회로정수들을 EM 해석 결과로부터 최적화한 후 수식으로 표현하였으며, 수식의 계수들은 모든 임피던스 경우에 맞도록 curve fitting을 통하여 구하였다.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2002년도 봄 학술발표회 논문집
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• pp.284-291
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• 2002

New information technology developments continue to have a significant impact on civil engineering fields. The objective of this study is to develop STEP-based database which will be able to store and manipulate the information of steel bridges over the life cycle. In this study, there are three steps to fulfil the objective to build database and develop the application module for that data model practically and effectively To begin with, STEP methodology for a development of data model has been used for modelling data structure. And then the data model for a steel bridge's shape and structural analysis information has been made up by using AP203 (configuration controlled design) and AP203 (composite and metallic structural analysis and related design) which are the international standard in STEP Lastly, the application module for an access to information of steel bridges has been developed by means of already made database. This study show efficiently the prototype of developing information system with the existing standard technology in civil engineering fields.

• International Journal of Safety
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• 제9권2호
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• pp.1-5
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• 2010

In order to analyze the potential rise of ground surface of grounding grid installed in buildings, the grounding simulator has been designed and fabricated as substantial and economical measures. This paper describes the study of touch and step voltages with grounding grid where earth leakage current is injected. To assess risk voltage of grounding grid, the grounding simulator and CDEGS program were used to obtain measured data and theoretical results of this study. The grounding simulator was composed of an electrolytic tank, AC power supply, a movable potentiometer, and test grounding electrodes. The potential rise was measured by grounding simulator, and the touch and step voltages were computed by CDEGS program. As a consequence, the touch voltage and step voltage above the grounding grid were very low, but were significantly increased near the edge of grounding grid.

• Journal of Power Electronics
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• 제12권1호
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• pp.164-171
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• 2012

Variable step size maximum power point trackers (MPPTs) are widely used in photovoltaic (PV) systems to extract the peak array power which depends on solar irradiation and array temperature. One essential factor which judges system dynamics and steady state performances is the scaling factor (N), which is used to update the controlling equation in the tracking algorithm to determine a new duty cycle. This paper proposes a novel stability study of variable step size incremental resistance maximum power point tracking (INR MPPT). The main contribution of this analysis appears when developing the overall small signal model of the PV system. Therefore, by using linear control theory, the boundary value of the scaling factor can be determined. The theoretical analysis and the design principle of the proposed stability analysis have been validated using MATLAB simulations, and experimentally using a fixed point digital signal processor (TMS320F2808).

• 한국정밀공학회지
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• 제28권7호
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• pp.821-826
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• 2011

This paper deals with an analysis of dynamic mechanism for the industrial two-step folding automatic door. A nonlinear equation of motion was derived in terms of folding angle to estimate driving forces. Based on this dynamic behavior, time taken during the door's opening well as their velocities were controlled so that the operating conditions can be obtained for the purpose of design. The stiffness of twisting spring was also investigated when the automatic door closed, because a dangerous accident takes place from the door's free falling. The current research will be a very useful tool in the near future for the dynamic analysis for the multi-step folding automatic door.

• Tribology and Lubricants
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• 제21권1호
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• pp.27-32
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• 2005

This paper shows a performance analysis for step type and conical type sealess cylinders. 2 dimensional Reynolds equation and finite difference numerical techniques are utilized for the performance analysis and the piston design. Centering forces of conical pistons are higher than those of step ones. Also, leakage flows of conical pistons are lower than those of step ones. But, the step type piston is practically suggested to apply for sealess cylinders because it is difficult that conical portion is precisely manufactured.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 춘계학술대회 논문집 반도체 재료 센서 박막재료 전자세라믹스
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• pp.183-186
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• 2004

Unipoled piezoelectric transformers were designed with different input and output area ratios. The voltage step-up ratio increased proportionally with increasing the input area. The piezoelectric transformers operated in each transformer's resonance vibration mode. In this paper, ANSYS(FEM program) was used for analysing piezoelectric transformers. We compared with analysis and experimental results. The voltage step-up ratio showed maximum value in output area of small size. Output characteristics of piezoelectric transformers with various size were simulated. The result of analysis showed 2~7 times higher voltage step-up ratio than a experiment result.

• 한국정밀공학회지
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• 제22권2호
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• pp.89-97
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• 2005

Thin plate correction of forming process that it is nowadays smile change of simple contact surface as it becomes possible that forecast dictionary numerically exactly to analyze comparative big comp displacement real industry spot problems between complicated and abnormal curved line shapes and thin plate and die more reliable and need many efforts yet economical analysis method is required and develops this efficient algorithm. This research analyzes correction of forming and examined possibility and validity of spot application using One-Step Finite Element Method. Its application is being increased especially in the automotive industrial area for the cost reduction, weight saving, and improvement of strength.