• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2010년도 추계학술대회 논문집
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• pp.543-543
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• 2010

The objective of this research is estimating the location of interested sound source by using the similarity between a beamformer output in time domain and the candidate signal. The waveform of beamformer output at the location of sound source is similar with the waveform emitted by that source. To estimate the location of sound source by using this feature, we define quantified similarity between candidate signal and beamformer output. The candidate signal describes the signal which is generated by interested source. In this paper, similarity is defined by four methods. The two methods use time vector comparison, and the other two methods use time-frequency map or linear prediction coefficients. To figure out the results and performance of localization by using similarities, we demonstrate two conditions. The one is when two pure tone sources exist and the other condition is when several bird sounds exist. As a consequence, inner product with two time-vectors and structural similarity with spectrograms can estimate the locations of interest sound source.

• 대한지구과학교육학회지
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• 제1권1호
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• pp.111-118
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• 2008

This study is aimed at analyzing earth conception the nine pre service teachers who are majoring in earth science education and classifying a special feature from the ontological categories. Open ended questionnaires and semi structured interviews which meant to contribute to identifying ontological categories of concepts involving study area were designed. Pre service teachers' ontological category about earth conception most showed to dynamic and proto process. In the results show that many pre service teachers recognize simply the conception to a material, a condition and a conversion of the state changing. Most of the pre service teachers show their intermediate understanding level about the earth inner construction according to the analyzed results of the drawing tasks and interviews. The main alternative conceptions show them through a definition of the plate, a wording definition between lithosphere and asthenosphere, a feature of the plate boundary, a heat convection in the earth inner, the earth inner heat source, the earth inner structure, a physical feature of the mantle.

• 대한전기학회논문지
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• 제39권6호
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• pp.545-556
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• 1990

A design method of a current source using 12-pulse phase-controlled rectifier (PCR) is presented. The critical inductance of the 12-pulse PCR is derived and it is shown that the critical inductance can be reduced using a current source. The control circuit of the 12-pulse PCR with an inner fast dynamic loop is proposed to give the frequency synchronism and to reduce the subharmonics due to the unbalance of the transformer of the power line. This circuit is analyzed and its dynamic loop is optimized. The optimal constant PIMF (proportional, integral and measurable variable feedback, and feedforware) controller is also designed using the time-weighted quadratic performance index. It is shown via experimental results that the proposed design method gives high dynamic and static performance of the current source using the 12-pulse PCR.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 하계학술대회 논문집 A
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• pp.467-469
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• 2001

This paper presents an efficient location estimation methodology for a partial discharge(PD) source in the power transformer. The methodology previously proposed is not suitable for locating a PD source because the ultrasonic signal with medium attenuated through the inner structure. In general, the propagation characteristic of ultrasonic signal with medium is different. Therefore, using this propagation characteristic, we can detect the location of PD source. In this paper, the proposal algorithm finds the PD source using three sensors attached to one side of the transformer without attenuation of the ultrasonic signal and applying the neural network based geometrical method. The proposed methodology demonstrates the effectiveness and validity on an experimental transformer.

• E2M - 전기 전자와 첨단 소재
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• 제8권5호
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• pp.626-632
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• 1995

In this paper, The effect of the impedances in SNOSFET's memory devices has been developed. The effect of source and drain impedances measured by means of two bias resistances - field effect bias resistance by inner region, external bias resistance. The effect of the impedances by source and drain resistance shows the dependence of the function of voltages applied to the gate. It shows the differences of change in source drain voltage by means of low conductance state and high conductance state. It shows the delay of threshold voltages. The delay time of low conductance state and high conductance state by the impedances effect shows 3[.mu.sec] and 1[.mu.sec] respectively.

• 제어로봇시스템학회논문지
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• 제14권6호
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• pp.515-518
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• 2008

Organic light emitting diode(OLED) is one of the most promising type of future flat panel display. A linear source is used to deposite organic vapor to a large size OLED substrate. An electric heater which is attached on the side of linear source heats the organic powder for the sublimation. The nozzle of heater, which is attached at the top of the linear source has an optimal temperature. An numerical analysis has been performed to find optimal heater position for the optimal nozzle temperature. A commercial CFD program, FLUENT, is used on the analysis. Two-dimensional and three-dimensional analysis have been performed. The analysis showed that the heater should be attached at the outer side of crucible wall rather than inner side of housing, which was original design. Eighteen milimeter from the top of the linear source was suggested as the optimal position of heater. Improving thermal performance of linear source not only helps the uniformity of organic vapor deposition on the substrate but also increase productibity of vapor deposition process.

• Nuclear Engineering and Technology
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• 제50권3호
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• pp.446-452
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• 2018

To improve the accuracy and safety of irradiation tests in High flux Advanced Neutron Application ReactOr (HANARO), the nuclear energy deposition rate, which is called nuclear heating, was estimated for an irradiation capsule with an iridium sample in the irradiation hole in order. The gamma rays emitted from the radioisotopes (RIs) of the structural materials such as flow tubes of fuel assemblies and heavy water reflector tank were considered as radiation source. Using the ORIGEN2.1 code, emission rates of delayed gamma rays were calculated in consideration of the activation procedure for 8 years and 2 months of HANARO operation. Calculated emission rates were used as a source term of delayed gamma rays in the MCNP6 code. By using the MCNP code, the nuclear heating rates of the irradiation capsules in the inner core, outer core, and heavy water reflector tank were estimated. Calculated nuclear heating in the inner core, outer core, and heavy water reflector tank were 200-260 mW, 80-100 mW, and 10 mW, respectively.

• 한국분무공학회지
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• 제29권3호
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• pp.124-133
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• 2024

Heat pumps play a crucial role in achieving the 2050 Net-Zero targets in many countries worldwide. This study addresses this issue by modifying simulation conditions and selecting relevant cases to determine optimal COP conditions using Simulink. By analyzing the efficiency of heat pump heating, utilizing Simulink models provided by MATLAB, and evaluating economic feasibility, we aim to identify the key factors influencing heat pump performance, including the heat source type, refrigerant, heating set temperature, and piping. Our goal is to establish optimal conditions for maximizing the efficiency of these eco-friendly systems while considering economic factors. In this study, it was confirmed that the heat exchanger flow arrangement of the air-source heat pump using R407c was set to cross-flow, and the diameter of the heat exchanger inner tube was set to 0.95 times the existing size, which was found to be optimal for maximizing efficiency. The COP was approximately 4.07 under these conditions.

• 한국전자통신학회논문지
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• 제9권7호
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• pp.753-759
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• 2014

본 논문에서는 전원무결성(Power Source Integrity) 해석을 기반으로 PCB(Printed Circuit Board)내부 전원 선로의 RLC 공진(Resonance)현상을 해석하고 PCB내부 공진현상 감쇄를 위한 설계기법을 제시한다. 제시하는 기법은 PCB의 구조적 특성으로 형성되는 공진주파수를 예측하며, 공진현상 감쇄를 위한 디커플링 캐패시터의 적용위치 및 용량을 결정할 수 있다. 본 논문에서는 산업용 제어기 내부의 메인보드 회로 시뮬레이션 모델을 통해서 PCB 공진현상 감쇄 설계기법에 대한 타당성을 검증하였다. 본 연구결과는 향후, PCB 회로 설계에서 PDN(Power Delivery Network)구조의 안정도 향상에 기여할 것으로 기대된다.

• 대한의용생체공학회:의공학회지
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• 제24권1호
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• pp.23-29
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• 2003

요통환자의 약40%가 추간판 자체에 의한 요통, 연관통 환자로 추정되며, 그에 따라 추간판절제술과 같은 침습적인 시술이 진행되어 왔다. 최근 최소침습적이며 간편하고 경제적인 방법이 선호 받아 추간판 전기열치료(IDET-Intradiscal electrothermal therapy)란 방법을 이용한 시술이 소개되었다. 본 논문은 IDET 시술 시 가장 중요한 요소인 열원의 온도와 열원을 가하는 시간 및 그에 따른 추간판 내의 온도 분포를 연구 하고자 하였다. 그 방법으로 실험과 유한요소해석을 수행하였으며. 또한 임상적으로 알려진 통증을 완화시키는 두 가지 메카니즘에 의한 온도범위를 확인하였다. 그 결과 열원을 1,020초 동안 8$0^{\circ}C$로 유지했을 때 섬유륜 부분에서는 열원으로부터 15.6mm 떨어진 곳까지 45$^{\circ}C$ 이상(메카니즘 1-열에의한 섬유륜의 응고)의 온도분포를 보임을 확인하였고, 수핵 부분에서는 9mm 떨어진 곳까지 6$0^{\circ}C$ 이상(메카니즘 2-열에의한 수핵의 수축)의 온도분포를 보임을 확인하였다.