• 한국전산유체공학회지
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• 제11권2호
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• pp.56-61
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• 2006

As the size and dimension of target problems in the field of computational engineering including CFD gets bigger and higher, it is needed to have more efficient and flexible data visualization environment in terms of software and hardware. Even though it is still manageable to use a mouse in controlling 3-dimensional data visualization, it would be beneficial to use 3-D input device for 3-D visualization. 'Data Glove' is one of the best 3-D input devices, because human hands are best tools for understanding 3-D space and manipulating 3-D objects. Signals coming from 'Data Glove' are analog and very sensitive to finger motions, therefore signal filtering using a digital filter is applied. This paper describes our experience and benefits of using data gloves in controlling 3-dimensional postprocessing softwares.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 추계학술대회 논문집 학회본부
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• pp.515-517
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• 1997

In the industrial motor drive system, a shaft torsional vibration is 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, two-degree-of-freedom(TDOF) control of the two-mass resonant system using the $H_{\infty}$ filter is proposed. TDOF control method satisfies the command following property and the internal stability at the same. The $H_{\infty}$ filter is robust in noise and disturbance. Simulation results show the validity of the proposed control method.

• 대한전기학회논문지:시스템및제어부문D
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• 제54권5호
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• pp.324-326
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• 2005

An adaptive Chunk algorithm is newly devised and a collaborative streaming is designed for high quality multimedia streaming service under time varying traffic conditions. An LMS based prediction filter is used to compensate the effect of time varying background traffic of the WAN. The underflow is generated for the $20\~28\%$ of the data stored in the central server by applying the FARIMA(Fractional Autoregressive Integrated Moving Average) traffic modeling method. The proposed algorithm is tested with the MPEG-2 video files and compensates $71\~85\%$ of central stream underflow.

• International Journal of Fuzzy Logic and Intelligent Systems
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• 제8권2호
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• pp.100-104
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• 2008

In this paper, intelligent filtering methodology for masterarm translation signal is proposed. Fidelity and stability are contradicting factors in teleoperation. Human hand trembling filtering is one of the problems in telemanipulation field. During every operation the hand has a certain vibration that can affect the quality of teleoperation, especially in carrying FPD (Flat Panel for Display), nanomanipuation and other precise tasks. It is very important to study the kinesthetic perception of the human and to optimize the teleoperation system accordingly. To cancel out the influence of human's hand vibration the signal from the masterarm should be filtered. One of the feasible solutions is to use an intelligent filter based on fuzzy logic, which is a very flexible instrument. Applying intelligent filtering methodology, we can use some heuristic methods to solve the filtering problem.

• Structural Engineering and Mechanics
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• 제57권1호
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• pp.21-43
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• 2016

A conditional probability based approach known as Particle Filter Method (PFM) is a powerful tool for system parameter identification. In this paper, PFM has been applied to identify the vehicle parameters based on response statistics of the bridge. The flexibility of vehicle model has been considered in the formulation of bridge-vehicle interaction dynamics. The random unevenness of bridge has been idealized as non homogeneous random process in space. The simulated response has been contaminated with artificial noise to reflect the field condition. The performance of the identification system has been examined for various measurement location, vehicle velocity, bridge surface roughness factor, noise level and assumption of prior probability density. Identified vehicle parameters are found reasonably accurate and reconstructed interactive force time history with identified parameters closely matches with the simulated results. The study also reveals that crude assumption of prior probability density function does not end up with an incorrect estimate of parameters except requiring longer time for the iterative process to converge.

• Journal of Electrical Engineering and Technology
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• 제11권3호
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• pp.618-628
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• 2016

Active power filter (APF) has been proved as a flexible solution for compensating the harmonic distortion caused by nonlinear loads in power distribution power systems. Digital repetitive control can achieve zero steady-state error tracking of any periodic signal while the sampling points within one repetitive cycle must be a known integer. However, the compensation performance of the APF would be degradation when the grid frequency varies. In this paper, an improved repetitive control scheme with frequency adaptive capability is presented to track any periodic signal with variable grid frequency, where the variable delay items caused by time-varying grid frequency are approximated with Pade approximants. Additionally, the stability criterion of proposed repetitive control scheme is given. A three-phase shunt APF experimental platform with proposed repetitive control scheme is built in our laboratory. Simulation and experimental results demonstrate the effectiveness of the proposed repetitive control scheme.

• Journal of Power Electronics
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• 제18권6호
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• pp.1889-1900
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• 2018

Harmonic current mitigation is vital in power distribution networks owing to the inflow of nonlinear loads, distributed generation, and renewable energy sources. The active power filter (APF) is the current electrical equipment that can dynamically compensate for harmonic distortion and eliminate asymmetrical loads. The compensation performance of an APF largely depends on the control strategy applied to the voltage source inverter (VSI). Model predictive control (MPC) has been demonstrated to be one of the effective control approaches to providing fast dynamic responses. This approach covers different types of power converters due to its several advantages, such as flexible control scheme and simple inclusion of nonlinearities and constraints within the controller design. In this study, a finite control set-MPC technique is proposed for the control of VSIs. Unlike conventional control methods, the proposed technique uses a discrete time model of the shunt APF to predict the future behavior of harmonic currents and determine the cost function so as to optimize current errors through the selection of appropriate switching states. The viability of this strategy in terms of harmonic mitigation is verified in MATLAB/Simulink. Experimental results show that MPC performs well in terms of reduced total harmonic distortion and is effective in APFs.

• 대한전자공학회논문지
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• 제17권4호
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• pp.11-17
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• 1980

이 논문은 디지탈 필터를 구성하는 기법과 측정 결과를 고찰한 것이다. 필터는 PL 방식에 따라 구성하였으며 DMA와 μp의 연산제어 프로그램을 이용하였다. 이로써 PL 방식의 단점인 플렉시빌리티 (flexibility)의 문제를 일부 보완할 수 있었고, 일반용 μp에 의한 필터 구성보다 고속연산수행이 가능하였다. 구성결과 15 KHz의 셈플링주파수( )를 리얼타임으로 처리할 수 있었으며 이는 DMA 제어신호 실행시간 58 μsec에 의하여 제한됨을 알았다. 측정결과 fs =14 KHz 일때 버터워스 (Butterworth)인 경우 1665 Hz, 체비세프(Tchebichef)에서는 1455Hz의 저지주파수(fsp)까지 설계조건과 근사한 필터특성을 얻을 수 있었다. 측정값에 대한 오차는 버터워스인 경우 fc = 500Hz에서 +0.2dB, fsp =1000Hz 애서 -1.1 dB 이었으며 체비세프인 경우 fc =500Hz에서 +0.ldB, fsp =750Hz에서 + 0.2dB 이었다.

• 한국산학기술학회논문지
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• 제17권2호
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• pp.299-306
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• 2016

본 논문에서는 센서 네트워크를 이용하여 의사의 동작을 흉내 낼 수 있는 내시경 취급로봇의 형상 예측방법이 제안된다. 3축 지자기계와 3축 가속도 계로 이루어진 단위센서가 CAN버스 통신을 통하여 네트워크를 구성한다. 각각의 센서 유니트는 연성 튜브로 만들어진 로봇의 길이방향 위에 있는 점들의 각들을 검출하는 데 사용된다. 센서 네트워크로부터 수신된 신호들은 Butterworth lowpass filter를 이용하여 필터링 된다. 여기서 우리는 노이즈 제거를 위하여 버터워쓰 필터를 설계하였다. 최종적으로 로패스 필터에 의하여 노이즈가 걸러진 신호들을 처리하여 Euler 각이 추출된다. 이 Euler 각을 이용하여 sensor network 상에 있는 각 센서의 위치가 추정된다. 우리는 로봇 바디가 링크와 관절들로 구성되어 있다고 가정한다. 그러면 각 센서의 위치는 각 링크의 중심에 부착되어 있는 것으로 가정할 수 있다. Euler 각과 kinematics chain model로부터 링크의 위치를 결정할 수 있다. 각 링크를 매끈하게 연결할 수 있도록 하기 위해 각 센서의 위치사이에 보간이 수행되어 최종적으로 작동 중에 있는 내시경의 최종형상이 얻어진다. 실험 결과는 제시된 센서 네트워크에서 추정된 Euler angle과 kinematic chain model을 이용하여 추정된 serial link의 형상으로부터 내시경형상을 가시화 할 수 있음을 보여준다.

• 한국지능시스템학회논문지
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• 제21권6호
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• pp.755-760
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• 2011

본 논문은 파티클 필터(particle filter)를 이용한 레이저 내비게이션(laser navigation)의 위치측정 성능 향상에 관한 연구이다. 레이저 내비게이션은 무선항법장치(wireless navigation system)로써 무인 자율주행 장치(automatic guided vehicle)의 위치측정 및 제어에 주로 사용되며, 이는 기존의 유선유도장치(wired guidance system)들에 비해 유지보수에 유연하면서도 완전한 자율주행이 가능하다. 하지만 무선항법장치인 레이저 내비게이션은 반응속도가 느리며 고속주행 혹은 회전주행 시에 위치 정밀도가 크게 떨어지게 된다. 본 논문에서는 이와 같은 문제점을 해결하기 위해, 비선형(non-linear)/비가우시안(non-gaussian)의 시스템에서도 강인한 특성을 지닌 파티클 필터를 이용하여 위치 정밀도를 향상시키는 방법을 제안한다. 제안한 방법의 성능을 검증하기 위해, 레이저 내비게이션과 엔코더, 자이로가 장착된 지게차 AGV(automatic guided vehicle)를 사용하였으며, 제안된 방법과 상용화된 레이저 내비게이션의 위치측정 결과를 비교하였다. 실험 결과, 제안된 방법이 상용화된 레이저 내비게이션의 위치 정밀도에 비해 약 66.5% 향상됨을 확인하였다.