• 동력기계공학회지
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• 제2권2호
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• pp.60-66
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• 1998

Positioning performance with a normal pneumatic positioning system, is mainly affected by friction force on the actuator and nonlinear characteristics of the control valve. We proposed a positioning system which is composed of a pneumatic actuator and high speed control valve. for accurate and speedy positioning. Driving piston on the actuator is mounted with externally pressurized air bearings to clear the friction force. This paper studies a method in order that improves positioning ability of the pneumatic positioning system considering the nonlinear characteristics of the control valve and the actuator.

• 동력기계공학회지
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• 제7권2호
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• pp.11-16
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• 2003

Because of the advancement of digital computers and software technologies, simulation methods have been used to reduce time and costs. A lot of simulation methods have been developed for the improvement of charging efficiency on the intake and exhaust system of engines. In this study, as a basic step for the development of the gas flow simulation program for the intake and exhaust system, the gas flow in a pipe-orifice system was calculated with three algorithms(Method of Characteristics, MacCormack Method for conservation, and MacCoramck Method for nonconservation). The calculated results using three numerical algorithms were compared with measured result to verify the calculation accuracy.

• 전기학회논문지
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• 제57권10호
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• pp.1703-1707
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• 2008

Low frequency oscillation of inter-area system is important problem in power system areas because the operation conditions of power system depend on it. Generally, the analysis of the problem is used by small signal stability. Especially, the analysis results are affected by decision of load models. In this paper, the effect of the analysis results was studied according to load component characteristics. ZIP model, popular in large-scaled power system analysis, was used as the load model. Many cases were studied according to the combination of ZIP model in inter-area system.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제49권6호
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• pp.431-440
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• 2000

This paper analyses the dynamic performance of HVDC System connected to a weak AC system for various exciter characteristics of synchronous machines connected at the converter bus. Conventionally capacitors are used to supply reactive power requirement at a strong converter bus. But the installation of synchronous machine is essential in a isolated weak network to re-start after a shutdown of HVDC and to increase system strength. The dynamic performance of a synchronous machine depends on the characteristics depends of its exciter. In this paper, several exciter types are used to investigate their effect on the dynamic performance of the HVDC system and modifications to standard exciter topologies are suggested to mitigate observed problems.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.1101-1104
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• 2003

In this paper, we performed the study on the operation characteristics of tele-grasping using the developed experimental system. The experimental system consists of master and slave gripper. and signal processing system. For the stable grasping of an object, this system feedback the normal force obtained from the straingage of the slave gripper to magnetic particle brake of the master gripper through the signal processing system. This experimental system can control the grasping force in remote using the force feedback device. Some experimental results of the-tele-grasping are presented and discussed

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2003년도 추계학술대회논문집
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• pp.1089-1094
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• 2003

A main vibration source in HDD is arisen from high rotating disk/spindle, and vibration suppression of the disk-spindle system becomes a critical issue and a major concern for high performance of the drive. In this paper, we study the feasibility of suppressing unwanted vibration of disk-spindle system of the HDD by external shock and excitation utilizing piezoelectric shunt damping methodology. By considering dynamic characteristics of the disk-spindle system through modal analysis, a target vibration mode is determined and then the piezoelectric material is carefully integrated to the modified drive. In order to maximize improvement of vibration characteristics of the proposed system, shunt circuit is optimally designed via tuning processes. Finally, the vibration characteristics of the high rotating disk-spindle system of the proposed drive is experimentally evaluated in frequency domain.

• 소음진동
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• 제3권3호
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• pp.231-243
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• 1993

The dynamic characteristics of two types of mathematical models for a rigid body suspension system are analyzed and compared in this paper. One is a linearized model which is commonly used in the engine mount system analysis, the other is a nonlinear model which usually applied to the pendulum type system. The typical 3 d.o.f's mathematical model, for convenience, is chosen as a simulation model, because it has fundamental dynamic characteristics of suspension system. Time responses and unbalance responses of the rigid body, transmitted forces and torques are simulated by using the mathematical model. From the results of computer simulation, it is approved that he nonlinear model is valid and the linearized model gives erroneous results in the case of the pendulum type suspension system. In addition, in this study the effects of design change on the dynamic characteristics of the suspension system are investigated. Mount locations, mount angles, lengths, stiffness and damping coefficients of suspension bars are chosen as design parameters.

• 전기학회논문지
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• 제56권11호
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• pp.1955-1961
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• 2007

In this paper, we propose the mathematical model for the vehicle system including running characteristics. The well defined model for a system is necessary to study and to enhance system performance. To model the dynamic properties of vehicle system, we have considered two fundamental parts. The first part is the motion equations for vehicle based on Newton's second law. The second part is the torque dynamics of the traction motor. These parts are affected by outer conditions such as adhesive coefficient, running resistance and gradient resistance. The each parts are presented by the numerical formula. To test the driving characteristics of the developed model, we performed the simulations by dynamic system simulation software, "SIMULINK" and the results are given for several conditions.

• 항공우주시스템공학회지
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• 제15권4호
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• pp.7-10
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• 2021

Including 425 Program, which is Korean military surveillance and reconnaissance satellite, there were mostly civil-driven space programs in Korea. However, there are increasing numbers of military demand-driven space program in nowadays. Furthermore, it is positive effects on launch vehicle development in Korea that the termination of Korea-U.S. missile guideline. In this paper, it emphasizes the needs of system engineering(SE) management method which meets both defense system's characteristics and space's characteristics. These characteristics are such as non-fixable after the launch, the security issue in defense system. And it also introduces SE tool, methodology and its philosophy. There are several functions that data management, issue management, risk management, and technical requirement management. Also describing its implications and direction of improvement.

• Journal of Electrical Engineering and Technology
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• 제10권3호
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• pp.1370-1376
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• 2015

Generally, an autotransformer(AT) feeding system consists of double tracks, up and down, with the trolley wire and feeder wire of the up and down tracks connected in the sectioning post(SP). Consequently, load current or fault current flows on two tracks based on catenary impedance characteristics, making it difficult to estimate catenary impedance accurately. This paper presents a technique for the estimation of catenary impedance using boosting current compensation based on the current division characteristics of an AT feeding system to improve the operation performance of impedance relay. To verify the technique, we model an AT feeding system through a power analysis program (PSCAD/EMTDC) and simulate various operation and fault conditions. Through the simulation, we confirmed that the proposed technique has estimated catenary impedance with a similar degree of accuracy to the actual catenary impedance