• Structural Engineering and Mechanics
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• 제16권4호
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• pp.423-440
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• 2003

Arbitrary Lagrangian Eulerian finite element methods gain interest for the capability to control mesh geometry independently from material geometry, the ALE methods are used to create a new undistorted mesh for the fluid domain. In this paper we use the ALE technique to solve fuel slosh problem. Fuel slosh is an important design consideration not only for the fuel tank, but also for the structure supporting the fuel tank. "Fuel slosh" can be generated by many ways: abrupt changes in acceleration (braking), as well as abrupt changes in direction (highway exit-ramp). Repetitive motion can also be involved if a "sloshing resonance" is generated. These sloshing events can in turn affect the overall performance of the parent structure. A finite element analysis method has been developed to analyze this complex event. A new ALE formulation for the fluid mesh has been developed to keep the fluid mesh integrity during the motion of the tank. This paper explains the analysis capabilities on a technical level. Following the explanation, the analysis capabilities are validated against theoretical using potential flow for calculating fuel slosh frequency.

• 한국정보통신학회논문지
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• 제3권3호
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• pp.533-540
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• 1999

본 논문에서는 구형 패치를 이용하여 GPS용 마이크로스트립 안테나를 설계하였으며 안테나의 특성을 확인하기 위하여 시뮬레이션을 통해 단일 구형 마이크로스트립 패치 안테나의 폭과 급전선을 변화 시켰다. 그리고 축비를 이용하여 우선회 원형편파 특성을 확인하였고, 결과를 통해 유한차분 시간영역법은 마이크로스트립 안테나를 설계하기 위한 효과적인 방법임을 확인하였다. 시뮬레이션을 통한 GPS위성으로부터 수신된 주파수의 공진점을 확인하였고, 측정치와 비교적 잘 일치하였다.

• 대한전기학회논문지
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• 제43권6호
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• pp.1027-1035
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• 1994

This paper aims to make an artificial arm control strategy. For this, we propose a new feature extraction method and design artificial neural network for the functional classification of myoelectric signal(MES). We first transform the two channel myoelectric signals (MES) for biceps and triceps into frequency domain using fast Fourier transform (FFT). And features were obtained by comparing the magnitudes of ensemble spectrum data and used as inputs to the three-layer neural network for the learning. By changing the number of units in hidden layer of neural network we observed the improvement of classification performance. To observe the effeciency of the proposed scheme we performed experiments for classification of six arm functions to the three subjects. And we obtained on average 94[%] the ratio of classification.

• Journal of international Conference on Electrical Machines and Systems
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• 제1권3호
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• pp.391-396
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• 2012

The Voltage Bus Conditioner(VBC) is a bidirectional DC-DC converter for damping the instability and any transients of the bus voltage in a DC Distributed Power System(DPS). In this paper, a PI controller for the VBC has been designed for the frequency domain. The proposed PI controller not only dampens the bus transients, but also keeps the storage voltage level. Simulation by Matlab/Simulink and experimental results are presented for the validity of the proposed control technique.

• 대한전자공학회논문지TC
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• 제44권1호
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• pp.123-131
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• 2007

본 논문에서는 채널 파라미터 추정을 위해 TD-SCDMA 기지국에 의해 방송되는 파일럿 신호를 이용하기 위한 FIR-Rake 수신기를 개발한다. FIR-Rake 수신기는 이동국에 대한 다중경로 간섭을 완화할 수 있다. 주파수 영역과 이산 영역에서의 해석, 그리고 컴퓨터 시뮬레이션은 제안 FIR-Rake 수신기가 전형적인 다중경로 페이딩 전파 환경에서 더 우수한 성능을 나타내는 것을 확인하였다.

• 한국해양공학회지
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• 제18권1호
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• pp.1-6
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• 2004

In this paper, the performance of a wave absorbing system using an inclined punching plate, was investigated. Using the multi-domain boundary element method (BEM), the reflection coefficients of an inclined punching plate were tested with various design parameters, such as inclined angle, porosity, and wave frequencies. To confirm the numerical solutions, the systematic model test was conducted at 2-D tank and square tank. The numerical results were in good agreement with the experimental results within the entire frequency range. It was found that an inclined punching plate had an excellent wave absorbing efficiency, compared to a horizontal one. Also, the optimal range of an inclined angle had an excellent wave absorbing efficiency, compared to a horizontal one the optimal range of the inclined angle is 10°<β<20°. The developed wave absorber was installed at KRISO's square basin, and is working effectively for various model tests.

• 전자공학회논문지C
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• 제34C권12호
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• pp.20-27
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• 1997

In this paper, a multiplying digital-to-analog converter (MDAC) circuit for low-power high-resolution CMOS algorithmic A/D converters (ADC's) is proposed. The proposed MDAC is designed to operte properly at a supply at a supply voltge between 3 V and 5 V and employs an analog0domain power reduction technique based on a bias switching circuit so that the total power consumption can be optimized. As metal-to-metal capacitors are implemented as frequency compensation capacitors, opamps' performance can be varied by imperfect process control. The MDAC minimizes the effects by the circuit performance variations with on-chip tuning circuits. The proposed low-power MDAC is implementd as a sub-block of a 10-bit 200kHz algorithmic ADC using a 0.6 um single-poly double-metal n-well CMOS technology. With the power-reduction technique enabled, the power consumption of the experimental ADC is reduced from 11mW to 7mW at a 3.3V supply voltage and the power reduction ratio of 36% is achieved.

• Structural Engineering and Mechanics
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• 제33권3호
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• pp.339-355
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• 2009

The sealed, tuned liquid column gas damper (TLCGD) with gas-spring effect extends the frequency range of application up to about 5 Hz and efficiently increases the modal structural damping. In this paper the influence of several TLCGDs to reduce coupled translational and rotational vibrations of plan-asymmetric buildings under wind or seismic loads is investigated. The locations of the modal centers of velocity of rigidly assumed floors are crucial to select the design and the optimal position of the liquid absorbers. TLCGD's dynamics can be derived in detail using the extended non-stationary Bernoulli's equation for moving reference systems. Modal tuning of the TLCGD renders the optimal parameters by means of a geometrical transformation and in analogy to the classical tuned mass damper (TMD). Subsequently, fine-tuning is conveniently performed in the state space domain. Numerical simulations illustrate a significant reduction of the vibrations of plan-asymmetric buildings by the proposed TLCGDs.

• 정보와 통신
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• 제24권3호
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• pp.76-86
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• 2007

This paper describes the RF performance issues of UE RF Transceiver for W-CDMA system based on 3GPP specifications. the parameters of transmitter and receiver are derived from the viewpoint of RF performance. In order for UE to achieve high performance, the transceiver performance requirements such as ACIR, EVM, Peak Code Domain Error, spectrum emission mask, frequency error stability and TX power control dynamic range for transmitter and reference sensitivity level, blocking characteristics, noise figure, ACS, linearity, AGC dynamic range for receiver are considered. On the basis of the required parameters, the UE RF transceiver is designed and then implemented. The evaluation of RF performance is accomplished through practical test scenarios.

• 대한전기학회논문지
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• 제45권1호
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• pp.60-66
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• 1996

Brushless DC(BLDC) motor have been increasingly used in machine tools and robotics applications due to the reliability and the efficiency. In control of BLDC motor, it is important to construct the controller which is robust to parameter variations and external disturbances. Variable structure controller(VSC) has been known as a powerful tool in robust control of time varying systems. In practical systems, however, VSC has a high frequency chattering which deteriorates system performances. In this paper, a binary controller(BC) which takes the form of VSC and MRAC combined is presented to solve this problem. BC consists of the primary loop controller and the external loop controller to change the gain of primary loop controller smoothly. So it can generate the continuous control input and is insensitive to parameter variations in the given domain. To confirm the validity, various investigations of control characteristics for various design parameters in a position control system of BLDC motor are carried out. (author). 11 refs., 18 figs., 1 tab.