• 한국산업융합학회 논문집
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• 제22권3호
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• pp.251-257
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• 2019

This paper proposes a new measurement method using virtual power concept to measure the effective value of 3-phase voltage with variable frequency. The conventional effective value measurement method uses a method of integrating data sampled during one or half cycle of the power voltage and averaging it. In this method, since the effective voltage is calculated every cycle, a time delay occurs in the measured effective voltage and it is s a problem to measure the effective value of a device whose frequency varies from time to time, such as a generator. The proposed 3-phase voltage rms measurement method has an advantage that it can measure accurate voltage RMS value regardless of measurement frequency variation. In particular, there is an advantage in that it is possible to measure a 3-phase effective voltage rather than an average value of the effective voltage of each phase in a 3-phase unbalance voltage. In addition, the validity of the proposed method is verified by using the Psim simulation tool and the experimental results are analyzed by applying the proposed measurement algorithm to the actual three phase synchronous generator voltage measurement experiment.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2011년도 전력전자학술대회
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• pp.461-462
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• 2011

In this paper, a static overmodulation method using the effective time to control the overmodulation is proposed. The effective time is derived from actual switching time interval. The proposed method reduces the complex operations such as complicated gating time. The experimental results have been simulated in MATLAB/SIMULINK.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2006년도 6th International Meeting on Information Display
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• pp.241-245
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• 2006

Reset is necessary for effective addressing in AC PDPs, but reset takes considerable time and produces background luminance. A reset method that takes less time but is effective for addressing is presented. Furthermore, this reset method produces almost negligible background luminance.

• Journal of Mechanical Science and Technology
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• 제17권4호
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• pp.545-561
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• 2003

We use the first-passage-time formulation by Torquato, Kim and Cule ［J. Appl. Phys., Vol. 85, pp. 1560∼1571 (1999) ］, which makes use of the first-passage region in association with the diffusion tracer's Brownian movement, and develop a new efficient Brownian motion simulation method to compute the effective conductivity of digitized composite media. By using the new method, one can remarkably enhance the speed of the Brownian walkers sampling the medium and thus reduce the computation time. In the new method, we specifically choose the first-passage regions such that they coincide with two, four, or eight digitizing units according to the dimensionality of the composite medium and the local configurations around the Brownian walkers. We first obtain explicit solutions for the relevant first-passage-time equations in two-and three-dimensions. We then apply the new method to solve the illustrative benchmark problem of estimating the effective conductivities of the checkerboard-shaped composite media. for both periodic and random configurations. Simulation results show that the new method can reduce the computation time about by an order of magnitude.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2005년도 춘계학술대회 논문집
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• pp.117-121
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• 2005

In this paper, an approximate time-effective approach to rigid-plastic finite element method is presented with its solution scheme and a volume compensation method is proposed to simulate rotary forging processes. The applicability is examined by comparing the results obtained by the presented approach with those by the conventional approach. The approach is applied to simulation of a rotary forging process fur a wheel bearing assembly. The analyzed results are compared with the experimental results.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2011년도 추계학술대회
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• pp.71-72
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• 2011

This paper presents a novel and direct dead time compensation method of the 3 phase inverter using space vector pulse width modulation(SVPWM) topology. In the turn on time calculation of the effective voltage, the dead time effect is directly compensated according to the current direction of the midium voltage reference. Since the turn on time of the effective voltage vector is affected by the dead time, the loss time is compensated to turn on time of the effective voltage vector. And the dead time is added to the calculated voltage vector switching times according to the current direction. For the more effective compensation, the direction of the midium phase current is considered by the practical direction and voltage drops in the power devices. The proposed method can compensate the dead time which is considered feedback error or direction of middle phase current without coordinate transform in added controller. The proposed dead time compensation scheme is verified by the computer simulation and experiments of 3 phase R L load.

• Journal of Biosystems Engineering
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• 제18권3호
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• pp.270-274
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• 1993

Many researches have been performed to shorten drying time and cost of red pepper in Korea. Nevertheless, an effective drying method for red pepper is not developed yet. This study was conducted to analyze the effect of opening ratio of red pepper's surface on drying for development of an effective drying method. The drying method with punching treatment is expected to be effectively utilized for shortening drying time and improving quality of red pepper.

• Investigative Magnetic Resonance Imaging
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• 제4권1호
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• pp.42-51
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• 2000

목적: Projection-type Fast Spin Echo (PFSE) 영상 기법은 일반적인 Fast Spin Echo (FSE) 기법과 비교하여 환자의 움직임과 혈류에 강한 장점이 있는 반면. $T_2$ 대조도(contrast)를 조절하기가 어려운 단점이 있다. 본 연구에서는 PFSE의 대조도를 이론적으로 분석하였고 컴퓨터 모의실험을 통하여 다양한 effective echo time (TE) 을 갖는 일반적인 FSE와 비교, 분석하였다. 또한 인체 실험을 통하여 제안한 PFSE 영상기법으로 움직 임과 혈류에 강인한 $T_2$ 강조 영상을 얻을 수 있음을 보였다. 대상 및 방법: 본 연구에서는 1.OT 전신 MRI 시스템에서 새로운 k-space의 배치를 갖는 PFSE 펠스 시권스를 구현하여, PFSE와 FSE 방식의 $T_2$ 대조도를 컴퓨터 모의설험과 인체 실험을 통하여 비교, 분석하였다. 컴퓨터 모의실험에서는 서로 다른 $T_2$ 값을 갖는 팬텀을 구현하여 다양한 effective TE에 대한 FSE 영상과 PFSE 영상을 재구성하여 대조도를 비교하였다. 인체 설험에서는 multi-slice $T_2$ 강조 두부 영상을 PFSE와 FSE로 얻어 영상기법간의 $T_2$ 대조도를 비교하였다. 결과: 이론적인 분석에서 PFSE의 $T_2$ 대조도는 effective TE가 80-l00ms 정도의 FSE 영상과 등가하게 나타나 $T_2$ 강조 영상을 얻을 수 있을 것으로 판단되었다. 컴퓨터 모의실험에서 PFSE 재구성 영상은 effective TE가 96ms인 FSE 영상과 대조도가 비슷하게 나타났다. 인체 실험에 서도 PFSE 영상은 effective TE가 96ms인 FSE 영상과 비슷하게 나타났으며. PFSE 방법이 FSE 방법에 비하여 움직 엄과 혈류와 관련한 artifact에 강인함을 확인 할 수 었었다. 결론: PFSE 기법은 k-space의 극좌표계에서 서로 다른 각도를 갖는 여러 line틀을 다중 스핀 에코 기법으로 측정하는 방식이다. PFSE기법은 FSE와 비교하여 환자의 움직임과 혈류에 강한 장점이 있는 반면, $T_2$ 대조도를 조절하기가 어려운 단점이 있다. 본 연구에서는 PFSE 방식으로 FSE와 대등한 $T_2$ 대조도 ($T_2$ 강조 영상)를 얻을 수 있음을 이론과 컴퓨터 모의실험 밝히고, 인체 실험을 통하여 확인하였다.

• Nuclear Engineering and Technology
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• 제54권3호
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• pp.811-816
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• 2022

This work presents the methodology used to expand the capabilities of the Monte Carlo code OpenMC for the calculation of reactor kinetic parameters: effective delayed neutron fraction β_eff and neutron generation time L. The modified code, OpenMC(Time-Dependent) or OpenMC(TD), was then used to calculate the effective delayed neutron fraction by using the prompt method, while the neutron generation time was estimated using the pulsed method, fitting Λ to the decay of the neutron population. OpenMC(TD) is intended to serve as an alternative for the estimation of kinetic parameters when licensed codes are not available. The results obtained are compared to experimental data and MCNP calculated values for 18 benchmark configurations.

• 한국멀티미디어학회논문지
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• 제23권11호
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• pp.1406-1417
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• 2020

Sounds that have been evaluated to be effective in inducing sleep are helpful to reduce sleep disorders. Generally, several sounds have been verified the effects by brainwave experiments, but it cannot be considered on all users because of individual variation for effects. Moreover, the effectiveness for inducing sleep is not known for all new sounds made by creative activities. Therefore, new classification system is required to collect new effective sounds with considering personal brainwave characteristics. In this paper, we propose a new sound classification method by applying improved MinHash cluster to brain waves. The proposed method will classify them through whether it is effective for sleep care by evaluation his brainwave during listening for each sound. In order to prove effectiveness of the proposed classification method, we conducted accuracy experiment for sleep sound classification using verified sleep induction sound. In addition, we have compared time for existing method and proposed method. The former is scored 85% accuracy in the experiment. We confirmed the latter one that the average processing time was reduced to 70%. It is expected to be one of method for pre-screening whether it is effective when a new sound is introduced as a sound for sleep induction.