• Proceedings of the Acoustical Society of Korea Conference
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• spring
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• pp.125-128
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• 1999

근거리음장 측정으로부터 원거리음장을 예측할 수 있는 이론적 모델 및 실험적 연구가 수행되고 있다. 본 논문에서 채택한 방법은 Helmholtz 적분식의 간단한 모델로써 단일주파수 코히어런트 음원의 근거리측정음장으로부터 원거리음장 예측이 가능한 기술이다. 이러한 단일 주파수, 코히어런트 음원의 원거리 수평방향지향성을 예측하기 위한 모델식 및 무향실에서 수행한 검증실험 결과를 소개한다 제안된 방법은 일반 소음원은 물론 잠수함 등의 수평방향 지향성의 예측에 적용가능하다고 판단된다.

• 제어로봇시스템학회:학술대회논문집
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• 1992.10a
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• pp.670-674
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• 1992

This paper presents a velocity regulation scheme for a DC motor subjected to random torque and velocity measurement noises of white noise type as well as unknown constant load torque (bias). The scheme separately estimates an unknown bias in addition to state estimation by the bias-free Kalman Filter, and reflects the effect of the bias estimate to the armature input voltage such that velocity variations be regulated. It is shown via computer simulations that the performance of the present scheme is superior to that of the conventional analog PI regulator.

• 제어로봇시스템학회:학술대회논문집
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• 1992.10b
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• pp.558-563
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• 1992

In this paper an identification of nonlinear continuous systems by using neural network is considered. The nonlinear continuous system is identified by two steps. At first, a linear approximate model of the continuous system with nonlinearity is obtained by IIR filtering approach. Then the modeling error due to the nonlinearity is reduced by a neural network compensator. The teaching signals to train the neural network is gotten by smoothing the measurement data corrupted by noise. An illustrative example is given to demonstrate the effectiveness of the proposed approach.

• 제어로봇시스템학회:학술대회논문집
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• 1995.10a
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• pp.110-114
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• 1995

This paper presents the on-board attitude determination algorithm for LEO (Low Earth Orbit) three-axis stabilized spacecraft. Two advanced star trackers and a three-axis Inertial Reference Unit (IRU) are assumed to be attitude sensors. The gyro in the IRU provides a direct measurement of the attitude rates. However, the attitude estimation error increases with time due to the gyro drift and noise. An update filter with measurements of star trackers and/or sun sensor is designed to update these gyro drift bias and to compensate the attitude error. Kalman Filter is adapted for the on-board update filter algorithm. Simulation results will be presented to investigate the attitude pointing performance.

• 제어로봇시스템학회:학술대회논문집
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• 1999.10a
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• pp.129-132
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• 1999

This paper deals with the optimal filtering problem constrained to input noise signal corrupting the measurement output for linear discrete-time systems. The transfer matrix H$_2$and/or H$_{\infty}$ norms are used as criteria in an estimation error sense. In this paper, the mixed $H_2/H_{\infty}$ filtering Problem in lineal discrete-time systems is solved using the LMI approach, yielding a compromise between the H$_2$and H$_{\infty}$ filter designs. This filter design problems we formulated in a convex optimization framework using linear matrix inequalities. A numerical example is presented.

• Journal of Institute of Control, Robotics and Systems
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• v.13 no.9
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• pp.861-867
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• 2007

A spreader pose control system using dual-electric compasses has been implemented by measuring the skew angle of the spreader with dual-electric compasses. In the conventional spreader pose measurement, CCD cameras, laser sensors or tilt sensors are mostly used. However those sensors are not only sensitive to the weather and disturbances but also expensive to build the system. To overcome the shortcomings, an inexpensive and efficient system to control the spreader pose has been implemented using the dual-magnetic compasses. Since the spreader iron-structures are noise sources to the magnetic compass, it is not considered to use the magnetic compass to measure the orientation of the spreader. An algorithm to eliminate the interferences of metal structures to the dual compasses has been developed in this paper. The 10:1 reduction model of a spreader control system is implemented and the control performance is demonstrated to show the effectiveness of the dual-magnetic compasses proposed in this research.

• Journal of the Society of Naval Architects of Korea
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• v.30 no.4
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• pp.46-60
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• 1993

Accurate measurements of fluctuating pressure in the cavitation tunnel are necessary to predict vibration and noise intensities in full scale ship. In this paper, the results of an experimental study on fluctuating pressure induced by a cavitating propeller are presented and discussed. Extensive measurements at several propeller revolutions are made using the flat plate to understand controversial problems of the effects of propeller revolution in the cavitation tunnel. The analysis of the uncertainties in experimental measurements and results is used to estimate the errors in uniform flow.

• Proceedings of the KSR Conference
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• 2007.05a
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• pp.169-174
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• 2007

Adopting articulated bogie system, the HSR350x and KTX have similar physical mechanical characteristic, but they show different dynamic characteristics due to different position of suspensions and those physical properties. The low level vibration frequency which effects on the ride comfort of passengers and the high level vibration frequency which is related to noise of vehicle have been measured by accelerometers mounted on Wheel sets, Bogies and Car bodies to analysis the dynamic characteristics of the High-Speed Trains. The KTX number 36 is utilized to measure the lateral and vertical acceleration value of car body, and total measurement system of HSR350x have been used to acquire acceleration data. The sampling frequency of data is 500Hz generally, but the Car body at TT2 of HSR350 has 1000Hz exceptionally.

• Proceedings of the KSR Conference
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• 2007.11a
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• pp.401-410
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• 2007

Form the application of long rail system the non-ballast steel plate bridges, fatigue strength increase and rail noise reduction can be expected. This is mainly form the reduction of the rail impact at the rail joint locations which already made to behave together from welds. In the high speed rail, application of long rail system is essential because without long rail system, the required serviceability level can not be achieved. But even with this long rail systems, the thermal expansion from the girder can not be absorbed in the normal bearing systems, and these expansion cause between girder and rail. Also unexpected rail buckling and fracture through rail thermal tension may happen. It was found through numerical analysis and field measurement that these problems can be avoided by semi-fixed bearing system. In this study, the benefits of non-ballast plate bridge through long rail system, especially at the point of girder stability, girder stiffness increase and bearing maintenance will be reviewed.

• Journal of Power System Engineering
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• v.12 no.5
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• pp.65-70
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• 2008

The purpose of this study is to verify availability of the acoustic emission in-situ monitoring method to the internal leak and operating conditions of the turbine major valves relating to safety for turbine operating and prevention of turbine trouble at nuclear power plants. In this study, acoustic emission tests are performed when the pressurized electro-hydraulic control oil flowed through turbine electro-hydraulic controller oil check valve and turbine power/trip fluid solenoid valve in the condition of actual turbine operating. The acoustic emission method was applied to the valves at the site, and the background noise was measured far the abnormal plant condition. To judge for the leak existence ell the object valves, voltage analysis and frequency analysis of acoustic signal emitted from infernal leak in the valve operating condition are performed. It was conformed that acoustic emission method could monitor for valve internal leak to high sensitivity.