• Proceedings of the KIPE Conference
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• 1998.07a
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• pp.5-9
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• 1998

In the high speed rail system, the distortion of the voltage and the current waveform of the input power line increases the power loss and make a several electro-magnetic problems such as EMI or the interference of the communication line. In this paper, the control scheme of the PWM converter to make a good power factor and to regulated the output voltage as well as to reduce the harmonic component of the input current is proposed. Also a control schem of the PWM converter in the parallel operation to reduce the harmonics of the input current is proposed

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.20 no.11
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• pp.1097-1102
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• 2010

In this paper, the energy flow analysis(EFA) of the body-in-white door of a real automotive was performed using the energy flow finite element method(EFFEM) to effectively predict the vibrational responses of built-up structures in the medium to high frequency range. To increase the validity of EFA results, the structural hysteresis damping loss factor was measured by the experiment using the concept of statistical energy analysis(SEA). As the excitation frequency increases, the predicted results simulated with EFFEM generally agree with the experimental results.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.05a
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• pp.202-207
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• 2002

This paper deals with a novel shunted actuator, which has a capability to suppress multi-mode vibration amplitudes by using a pair of piezoceramic patches. In order to describe the characteristic behaviors of shunted dampers connected with a series and a parallel resistor-negative capacitive branch circuit, the stiffness ratio and loss factor with respect to the non-dimensional frequency are considered. To obtain a guideline model of a piezo/beam system connected with a series and a parallel resistor-negative capacitor branch circuit, the governing equations of motion is derived through Hamiltons principle and a piezo sensor equation as well as a shunt damping matrix is developed. The theoretical analysis shows that the shunted actuator developed in this study can significantly reduce multiple-mode vibration amplitudes simultaneously over the whole structural frequency range.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.10a
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• pp.994-995
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• 2014

Supporting stiffness of seats is an important component affecting dynamic characteristics cognized by a passenger. To analyze dynamic characteristic of a seat for vehicles operating on various road conditions, the seat vibration from road irregularity should be understood and compared. In this study, the seat is analyzed as distributed supporting system. The dynamic stiffness is measured using masses. The characteristic of the seats is analyzed by measuring distributed dynamic stiffness. The distributed dynamic stiffness of the seat is estimated on various locations and the effects of each component such as spatial distribution, compression level and vibration amplitude are analyzed. The influence of seat cover, elastic support and flexible polyurethane foam on the measured stiffness was analyzed.

• Proceedings of the KIEE Conference
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• 2005.04a
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• pp.172-175
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• 2005

Recently international regulations governing the amount of harmonic currents(e.g IEC 61000-3-2) became mandatory and active Power factor correction (PFC) pre-regulator circuit became inevitable for the AC/DC converters. Among these topologies, the boost topology represents an optimum solution for a PFC pre-regulation in a high power application. This paper propose improved ZVT(Zero Voltage Transition) AC/DC PFC Boost using the average current control employing a soft-switching technique of the auxiliary switch with a minimum number of components. The conventional ZVT PFC Boost Converter has a disadvantage that the auxiliary switch turns off hard, which influences the overall efficiency and the EMI problem. In this paper, an improved ZVT PFC Boost converter using active snubber is proposed to minimize the switching loss of the auxiliary. The prototype of 100kHz, 640W system was implemented to show the improved performance.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2000.11a
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• pp.224-227
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• 2000

Modal damping characteristics of the flexural vibration of a sandwich beam with paaially inserted viscoelastic layer have been quantitatively studied using the finite element analysis in combination with an experiment. Antisymmetric mode shapes of the flexural vibration were visualized by the holographic interferometry and agreed with those calculated by the finite element simulation. Effects of the length and thickness of partial viscoelastic layers on the system loss factor($\mu$) and resonant frequency($\omega$) were considerably latge at both symmetric and antisymmetric modes of the sandwich beam.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.17 no.4
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• pp.126-132
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• 2008

The vibration and disturbances from operating the compact disk layer have an effect on the play ability. As the excitation sources of the compact disk player, there are the vibration of the motors and gears, impact by mechanical parts and the external excitations. So, most of the compact disk player have a anti-vibrational system, which is included some rubber or oil dampers. In this study, the vibration characteristics of rubber damper which is used home compact disk player are investigated. The materials and shape of rubber damper are changed, and the transmissibility is measured. As a conclusion, the natural frequency is moved to higher frequency and the transmissibility is reduced by the increasing rubber stiffness. In comparison to butyl rubber damper, the transmissibility of silicon damper was increased by larger restitution elasticity. The hollow damper was effective to reduced the transmissibility.

• Proceedings of the Korean Society Of Semiconductor Equipment Technology
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• 2004.05a
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• pp.163-168
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• 2004

Linear motor can directly apply to the system needed linear mot ions without rotary mot ions. To control a high-speed and high-resolution, the development of the linear motors is recently required in the high-integrated and speed process industry. This paper presents vibration analyses as well as measurement standards of the newly developed linear motors through analyzing the vibration characteristics and thermal behaviors of the advanced products. Vibration experiments are conducted for identifying the hysteresis and vibration level during operation. They are also included in the modal test to analyze the vibration. Analytic data using Finite Element Method (FEM) are compared with the results of the modal. Loss of temperature generated the linear motor leads to a serious deformation within its parts. The thermal behaviors are very important factor in linear motor. The FEM and experiments make it possible to understand these characteristics.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.15 no.1
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• pp.93-101
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• 2002

In this study, the stator form-winding sample coils based on silicone resin and polyimide were made for fault prediction and reliability estimation on the C-Class(200$\^{C}$ ) insulation system of traction motors. The complex accelerative degradation was periodically performed during 10 cycles, which was composed of thermal stress, fast rising surge voltage, vibration, water immersion and overvoltage applying. After aging of 10 cycles, the condition diagnosis test such as insulation resistance '||'&'||' polarization index, capacitance '||'&'||' dielectric loss and partial discharge properties were investigated in the temperature range of 20 ∼ 160$\^{C}$. Relationship among condition diagnosis tests was analyzed to find a dominative degradation factor and an insulation state at end-life point.

• Journal of Electrical Engineering and Technology
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• v.12 no.3
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• pp.1211-1218
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• 2017

In this paper, performance of rectangular shaped magnetic power pads for inductive power transfer (IPT) system according to ferrite structure is analyzed. In order to evaluate the influences of ferrite structure, six cases of magnetic power pads are proposed. Self-inductance, coupling coefficient, quality factor, and coil to coil efficiency are compared as the displacement increases in the direction of x or y axis. For accurate estimation, finite element method (FEM) simulation is used and loss components of the power pads are numerically calculated and considered. Through the simulation and measured results, effectiveness of protrusive and enveloping ferrite structure is identified.