• Proceedings of the KIEE Conference
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• 1996.07a
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• pp.368-371
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• 1996

The basic function of an excitation system is to provide direct current to the synchronous machine field winding. In addition, the excitation system performs control and protective functions essential to a satisfactory performance of a power system by controlling the field voltage and thereby the field current. This paper describes the characteristics and modeling of different types of excitation systems and discusses dynamic performances. In this paper, we modified IEEE ACIA and STIA excitation system to simple system. The automatic voltage control system which had been developed by KEPRI is used for experiments and simulations.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2000.11c
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• pp.533-542
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• 2000

Instrumentation and technologies are described for determining the vibration response characteristics of the pear with frequency range 5 to 320Hz. The computer program for controlling the vibration exciter and the function generator and for measuring the vibration response characteristics of the pear was developed. Mechanical properties such bioyield deformation, rupture deformation and apparent elastic modulus etc. were compared with the vibration response characteristics of the pear. The resonant frequency of the pear ranged from 53 to 102Hz and the amplitude at resonance was between 1.08 and 2.48g-rms. The resonant frequency and amplitude at resonance decreased with the increase of the sample mass, and they were slightly affected by mechanical properties such as bioyield deformation and rupture deformation. Regression analysis was performed among the relatively high correlated parameters from the results of correlation coefficient analysis.

• Journal of KSNVE
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• v.10 no.2
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• pp.269-279
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• 2000

This paper deals with the development of biomechanical model on a seat with backrest support in the vertical direction. Four kinds of biomechanical models are discussed to depict human motion. One DOF model mainly describes z-axis motion of hip, two and three DOF models describe z-axis of hip and head, and while nine DOF model suggested in this study represents more motion than the otehr model. Three kinds of experiments were executed to validate these models. The first one was to measure the acceleration of the floor and hip surface in z-axis, the back surface in x-axis, and the head in z-axis under exciter. From this measurement, the transmissiblities of each subject were obtained. The second one was the measurement of the joint position by the device having pointer and the measurement of contact position between the human body and the seat by body pressure distribution. The third one was the measurement of the seat and back cushion by dummy. The biomechanical model parameters were obtained by matching the simulated to the experimental transmissiblities at the hip, back, and head.

• Tribology and Lubricants
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• v.11 no.2
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• pp.56-62
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• 1995

The anisotropic pressure distribution of the hydrodynamic bearing may generate the unstable vibration phenomenon over a certain speed. These vibrations, known as whirl, whip or rotor instability, cannot be sustained over a wide range of rotational spees. Besides these vibrations not only perturb the normal operation of a rotating machine, but may also cause serious damage to the machinery system. And, it is really impossible to change one parameter without changing others, or difficult to fabricate the modified non-circular type bearing, with all the other cures used just now, In this study, hybrid bearing with magnetic exciter is designed for stability improvement of hydrodynamic bearing rotor system without changing mechanical parameters. For stability study, eigenvalue study of the bearing-rotor system is executed by finite element method and results of analyses and experiments show the possibilities of the stability improvement of the hydrodynamic bearing system by using the electricmagnetic force.

• Proceedings of the KIEE Conference
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• 1991.07a
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• pp.397-401
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• 1991

Low frequency oscillations have been observed in KEPCO system. This paper represents how to analyze the power system by using the AESOPS program and analyze the various factors affecting the damping characteristics of these oscillations in KEPCO system of 1986. The characteristics of load, the amount of power flow on the transmission line and the gain of exciter have a significant effects on the damping of the system while the governing system has only a minor one. With the Power System Stabilizers, the stability of the power system has been increased.

• The Journal of the Acoustical Society of Korea
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• v.5 no.4
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• pp.5-15
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• 1986

This pater is a study on the measurement of solid-borne sound propagation in buildings. The purpose of this paper is to present the data needed for comfortable building enevironment. Solid-Borne sound in apartment building was measured at the source of sound and at many receiving locations in building. Dispersion of the sound level was analyzed to understand noises level at different locations. Graphic method as well as polynomial regression techniques were employed. For this experiment, we made use of the TAPPING MACHINE according to the standard rules of ISO as a impulse exciter, and the measurement was carried out after the building has been all completed. Noticeable noise reductions were observed as the distance from the source to the receiving location increases.

• Proceedings of the KIPE Conference
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• 2017.11a
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• pp.57-58
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• 2017

This paper proposes a high efficiency hybrid generator which has a winding and PM(Permanent Magent) field together. The PM field can supply the enough flux to generate the no-load output voltage, and the field winding current can supply the flux to compensate the voltage drop from the load. Furthermore, the PM exciter can supply the enough power for the field of the generator. The detailed design and the FEM analysis are presented to verify the proposed hybrid generator. Then the experimental results shows the effectiveness of the proposed system.

• Proceedings of the KIPE Conference
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• 2011.07a
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• pp.46-47
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• 2011

하이브리드 발전시스템에서 전압과 주파수제어는 서로 다른 분산전원의 동기화 및 전력제어에 있어서 매우 중요하다. 본 논문에서는 디젤발전 시스템에서 여자기 제어기에 대한 제어알고리즘에 관한 것이며, 이는 기본 제어기 알고리즘에 여자기전류에 대한 전류 지령치를 첨가함으로서 제어기의 속응성 및 안정도를 개선할 수 있도록 하였다.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.762_763
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• 2009

본 논문에서는 영구자석형 동기전동기와 유도기 특성을 결합한 written-pole motor(WPM)의 운전특성을 다룬다. WPM은 회전자 표면의 자석을 운전 중 착자할 수 있도록 하는 exciter pole을 갖는 독특한 구조로서 유도기와 동기기의 특성을 동시에 나타낸다. WPM의 운전 원리를 설명하고 가전용으로 실제 설계, 제작된 WPM을 대상으로 실험을 통해 특성을 검증하였다.

• Proceedings of the KIEE Conference
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• 2007.04c
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• pp.59-61
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• 2007

This paper presents the characteristic analysis of the 40-kVA high speed synchronous generator considering the field current. The generator consist of the rotor with the short-circuited field coils connected armature coils of exciter and the stator with three-phase winding. To analyze the characteristics of the generator, the direct finite element method is applied.