• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1998.04a
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• pp.198-205
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• 1998

Recently, according as the supply of power steering system has been diffused, for the comfortable driving condition, the problem to reduce the noise and vibration of this system suddenly appeared. This system can be classified two systems of the pipe line and the pump. In this paper, it is described about the noise characteristic with the camring profile of the hydraulic vane pump. As a result, when it excesses tolerance, the noise is increased. Moreover, in the case of the same of cam-ring, the effect of the rotating speed is larger than the discharge pressure.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.4
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• pp.336-342
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• 2003

In this paper, a new differential detector is introduced, in which a solar cell is used to reduce the low frequency interference from environmental optical noise. The solar cell also supplies electrical power to the detector circuit using the optical noise power. The DC voltage from the solar cell is used as a power supply to the detector, and the AC voltage is used to reduce the optical noise in a photodiode with the differential detection method. The signal to noise ratio was improved by about 20 dB.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.11b
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• pp.1306-1312
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• 2001

In this study. the acoustic power balancing method to analysis HVAC system noise is presented. The method can consider not only forward but also backward propagations of noise generated by the operation of air supply units and aerodynamical disturbance at duct elements. This can be done by estimating sound transmission and reflection properties of duct elements. and balancing acoustic powers of total HVAC system. To verify the accuracy of the presented method. numerical analysis for a HVAC system is carried out and the results are compared with those obtained by a traditional empirical method. suggested by National Environmental Balancing Bureau.

• The Transactions of the Korean Institute of Power Electronics
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• v.19 no.3
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• pp.211-219
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• 2014

This paper proposes a low voltage high current LLC resonant converter for Green PC. Green PC is composed of a lot of blade PCs, and it is a centralized system to manage them in computer center. Green PC should require that its power supplies have several characteristics such as low output voltage, high output current, and high power conversion efficiency. Conventional PSFB (Phase Shift Full Bridge) converter is usually used as DC/DC converter for computer power supply because it has high power conversion efficiency thanks to ZVS (Zero Voltage Switching) operation under middle and high load conditions. However, this converter has some problems such as large switching noise and limitation of ZVS operation under light load condition. In order to improve the performance of power supply for Green PC, a new power supply using popular high efficiency LLC resonant converter for low voltage and high current application is proposed in this paper. The proposed power supply has ZVS capability over the entire load range, thus resulting in good efficiency and high switching frequency. Experimental results verify the performance of the proposed power supply for Green PC using 2[kW] (19[V], 105[A]) rated prototype converter.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.1
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• pp.196-200
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• 2015

The switching noise in the power electronics of the power conversion equipment (Power Conditioning System) for large energy storage devices are generated. Since the burst-level transient noise from being generated in the power system at a higher power change process influences the control circuit of the low voltage driver circuit. Noise may cause the malfunction of the control device even if no dielectric breakdown leads to a control circuit. To overcome this, this paper proposes the installation of an additional nano-surge protection device on the power supply DC output circuit of the battery management unit.

• ETRI Journal
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• v.32 no.2
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• pp.265-272
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• 2010

To supply a power distribution network with stable power in a high-speed mixed mode system, simultaneous switching noise caused at the multilayer PCB and package structures needs to be sufficiently suppressed. The uni-planar compact electromagnetic bandgap (UC-EBG) structure is well known as a promising solution to suppress the power noise and isolate noise-sensitive analog/RF circuits from a noisy digital circuit. However, a typical UC-EBG structure has several severe problems, such as a limitation in the stop band's lower cutoff frequency and signal quality degradation. To make up for the defects of a conventional EBG structure, a partially located EBG structure with decoupling capacitors is proposed in this paper as a means of both suppressing the power noise propagation and minimizing the effects of the perforated reference plane on the signal quality. The proposed structure is validated and investigated through simulation and measurement in both frequency and time domains.

• The Transactions of the Korean Institute of Power Electronics
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• v.4 no.6
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• pp.500-506
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• 1999

This paper presents the h밍h performance [GBT type auxiliary jXlWer supply designt.'Cl by new concept. For t the simplification and higher performance, the direct :3 level PWlVl inverter using the high capacity IGBT and t the 32bit DSP are adopted. The cost as well as bulk and weight is appreciably reduced about 40% lower than t those of conventional one. the electrical efficiency above 94~) o and the audible noise level is less than 65dB. In a addition, the TIID(Total lIannonic Distortion) factor is below 5% an이 the voltage fluctuation on a transient s state is below 10%.w 10%.

• Journal of Korea Society of Industrial Information Systems
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• v.20 no.1
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• pp.49-55
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• 2015

This paper proposes a 2.4 GHz RF oscillator with a very low close-in phase noise performance. This is composed of a low frequency crystal oscillator and three frequency multipliers such as two doubler (X2) and one tripler (X3). The proposed oscillator is implemented as a hybrid type circuit design using a discrete silicon bipolar transistor. The measurement results of the proposed oscillator structure show -115 dBc/Hz close-in phase noise at 10 kHz offset frequency, while only dissipating 5 mW from a 1-V supply. Its close-in phase noise level is very close to that of a low frequency crystal oscillator with little degradation of noise performance. The proposed structure which is consisted of a low frequency crystal oscillator and a frequency multiplier provides new method to implement a low power low close-in phase noise RF local oscillator.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.05a
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• pp.827-830
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• 2006

With recent advanced in portable electric devices, wireless sensor, MEMS and bio-Mechanics device, the new typed power supply, not conventional battery but self-powered energy source is needed. Particularly, the system that harvests from their environments are interests for use in self powered devices. For very low powered devices, environmental energy may be enough to use power source. In the generality of cases, these energy harvesting systems are used in the piezoelectric materials as mechanisms to convert mechanical vibration energy into electric energy. Through the piezoelectric materials, the ambient vibration energy could be used to prolong the power supply or in the ideal case provide endless energy f9r the devices. Therefore, the piezoelectric power harvesting cantilever beam is developed. Also, the output voltage and power are predicted in this study. We also discuss the developing system of the piezoelectric energy scavenger. An experimental verification of the model is also performed to ensure its accuracy.

• Proceedings of the KIPE Conference
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• 2005.07a
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• pp.137-139
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• 2005

본 논문에서는 30W급 스위칭형 직류전원장치 (Switching Mode Power Supply : SMPS)에 준공진형 프라이 백 스위칭 레귤레이터(quasi-resonant flyback switching regulator)를 적용하여 방사노이즈(radiation-noise)를 억제한 사례에 대하여 설명하고 있다. 기존의 PI사(社)의 TOP IC 시리즈$^{[1]}$와 같이 보편적으로 사용되고 있는 일명, 하드 스위칭(hard-switching)형 레귤레이터를 사용할 경우, 고속 스위칭시에 스위칭 손실(switching loss)과 스위칭 노이즈(switching noise)가 발생한다. 이로 인하여 SMPS의 발열에 따른 효율저화와 방사 노이즈에 의한 전파방해 등이 문제점이 된다. 본 논문에서는 일본의 Sanken사(社)에서 개발/시판중인 준공진형 스위칭 레귤레이터인 STR-F6000 IC 시리즈$^{[2]}$를 이용하여 프라이백 SMPS를 구성하여 방사노이즈를 저감하였다.