• 전력전자학회:학술대회논문집
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• 전력전자학회 1997년도 전력전자학술대회 논문집
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• pp.332-335
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• 1997

In the industrial motor drive system, a shift torsional vibration si often generated when a motor and a load are connected with a flexible shaft. This paper treats the vibration suppression control of such a system. In this paper, the state feedback controller of the two-mass resonant system using the H$\infty$ filter is proposed. The H$\infty$ filter is robust in noise and disturbance. Simulation results show the validity proposed controller.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 추계학술대회논문집
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• pp.722-726
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• 2007

In this paper we deal with a design of the integral sliding mode controller to suppress the disturbance force acting on the suspension system of the magnetically levitated train system. One of the important factors that cause the disturbance force acting on the suspension system comes from the low propulsion speed of linear induction motor. In this paper integral sliding mode controller is employed to reject the disturbance force produced by the propulsion system of the linear induction motor. In order to show the effectiveness of the designed controller a dynamic simulation is utilized and the sliding mode controller without integral compensator is compared with the proposed integral sliding mode controller to suppress the disturbance force.

• 한국통신학회논문지
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• 제30권12C호
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• pp.1248-1255
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• 2005

본 논문은 4세대 무선 통신방식의 하나인 OFDM 기반의 60GHz 무선 랜에서의 위상잡음의 영향에 관하여 논한다. 60 GHz 주파수 대역은 광대역 전송이 가능할 뿐만 아니라 산소에 의한 전파의 흡수감쇄가 크다는 특성 때문에 주파수 재활용에 대한 실내 무선환경에서의 무선 링크를 밀집시킬 수 있다는 장점이 있다. 그러나 낮은 주파수의 국부 발진기를 체배하거나 높은 주파수의 국부 발진기를 사용하는 경우, 발진기의 비이상적인 특성으로 인해 발생하는 위상잡음은 다중 반송파 시스템에서 공통위상 회전과 부반송파간 간섭의 원인이 된다. 이는 위상 변화에 민감한 OFDM 기반의 무선전송 시스템에 심각한 성능 저하를 발생시키는 원인이 되므로 반드시 해결해야 하는 문제이다. 본 논문에서는 시스템 구현이 용이한 위상잡음 억제 알고리듬을 OFDM 기반의 60 GHz 무선 랜 시스템에 적용하고 이에 따른 성능을 SER 측면에서 분석하였다. 60GHz 대역에서 발생하는 위상잡음 환경에서 위상잡음 억제 알고리듬을 적용한 경우, 그렇지 않은 경우에 비해 16-QAM, 64-QAM에서 각각 6dB, 7.5dB 정도의 SER 성능 향상을 보였다.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2004년도 제22회 춘계학술대회논문집
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• pp.460-465
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• 2004

ESPR project started in 1999 with METI and NEDO support as five-years program in order to develop necessary technologies for the next-generation SST engine. In ESPR program, jet noise reduction technologies are focused as environmentally compatible technologies, which are critical to realize next-generation SST. In designing a lobed mixer nozzle which is a jet noise suppression system, there are many difficulties to understand the detailed flow phenomena occurred in the system because of its complexity. Large Eddy Simulation (LES) was applied to the lobed mixer nozzle flow analysis in ESPR project. The results demonstrated that LES approach was capable of predicting mixing characteristics of a complicated flow.

• 한국산학기술학회논문지
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• 제14권10호
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• pp.4962-4969
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• 2013

본 실험의 목적은 TSE-SPIR 지방소거기법과 GE-PROSET 지방소거기법을 비교하여 복부자기공명영상에서 최적의 T2 강조 지방소거기법을 평가하고자 한다. 자기공명영상 검사는 16채널 다중채널을 사용하여 1.5 T(Philips, Medical System, Achieva)기기로 수행하였다. 모든 영상은 TSE-SPIR과 GE-PROSET을 이용하여 축면상(axial plane)을 얻었다. TSE-SPIR과 GE-PROSET에 대한 후복막 지방의 평균 SNRs는 31.50, 4.15 이었으며, 장간막 지방에 대한 SNRs는 32.39, 7.03이었다. TSE-SPIR과 GE-PROSET에서 장과 후복막 지방, 장간막 지방의 CNRs는 152.69, 74.54 와 26.12, 68.78이었다. 장벽에 대한 묘출도는 TSE-SPIR(2.4), GE-PROSET(1.8)로 TSE-SPIR가 높게 나타났으며, 췌장벽(pancreas wall)에 대한 묘출도는 TSE-SPIR(1.90), GE-PROSET(2.80)로 GE-PROSET가 높게 나타났다. 결론적으로, T2 강조 지방소거 복부자기공명영상에서 GE-PROSET 지방소거기법 보다 TSE-SPIR 지방소거기법이 우위성 있은 평가를 얻었다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2008년도 춘계학술대회논문집
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• pp.255-259
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• 2008

A soft-recoil system, which is a new technology, can dramatically reduce a recoil force. Due to the inaccurate explosion, various fault modes may happen. These fault modes can cause the serious damage of the recoil system and must be suppressed to avoid them. In the present study, the fault mode control method of the soft-recoil system is investigated. A hydraulic damper is working under normal mode and a MR damper is additionally working when the fault modes happen. In the design of the fault mode controller, the detection method of the fault mode is important as well as its suppression. The results of the simulation show that the soft-recoil system performs when the fault modes happen.

• ETRI Journal
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• 제32권2호
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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.

• 한국정보통신설비학회:학술대회논문집
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• 한국정보통신설비학회 2009년도 정보통신설비 학술대회
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• pp.293-297
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• 2009

In this thesis, design of a VCO(Voltage controlled Oscillator) with a novel tuning mechanism is presented for the Radar system. This circuit, the 9.5 GHz oscillator is designed and implemented by restructuring microstrip resonator to raise Q value and to require a wide frequency tuning range. This product is fabricated on 2.6 Teflon substrate and device is NE722S01. In this paper, The new microstrip resonator VCO is proposed to achieve the characteristic of a wide frequency tuning range. This microstrip resonator VCO shows the phase noise characteristic of -108.3 dBc/Hz at 1 MHz offset from the fundamental frequency, the output power of 5.7 dBm and the second harmonic suppression of -38 dBc for the VCO are obtained. The manufacture VCO shows a frequency tuning range of 193.8 MHz. The proposed micro trip resonator VCO can be used for X-band Radar System with required tuning range.

• 한국소음진동공학회논문집
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• 제12권2호
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• pp.124-131
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• 2002

This paper presents the design of an active vibration suppression controller for an air-spring type vibration isolation table. Firstly, isolation system model is constructed considering the isolation table, attached equipment and voice-coil actuator. An active control system is designed based on frequency-shaped sliding mode control theory rewarding high frequency uncertainties with respect to attached equipments on the isolation table. Finally. the performance of the active isolation system is evaluated by simulation under some disturbance conditions which are transmitted from base structure of the isolation system.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 추계학술대회논문집
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• pp.522-524
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• 2005

In this paper, we address an actuator system, which suppresses the micro-vibration engaged by environment. The actuator system consists of two modules with a permanent and an electromagnet. In vertical mode, one module is upper the other is lower. For optimal control of alternating vibration, the rate of the attraction force and the repulsion force is exactly one. Generally, the repulsive force is smaller than the attractive force. For linear control of engaged vibration, the ratio of repulsive force and attractive force is designed to equal. The actuator system will be applied to an active vibration control system for precise vibration suppression. In this paper, the actuator structure and its important sizes are calculated by RMS and FEM analysis.