• Journal of Power Electronics
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• 제16권2호
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• pp.553-563
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• 2016

This paper presents a digital hardware implementation of a real-time simulator for a multiphase drive using a field-programmable gate array (FPGA) device. The simulator was developed with a modular and hierarchical design using very high-speed integrated circuit hardware description language (VHDL). Hence, this simulator is flexible and portable. A state-space representation model suitable for FPGA implementations was proposed for a dual three-phase induction machine (DTPIM). The simulator also models a two-level 12-pulse insulated-gate bipolar transistor (IGBT)-based voltage-source converter (VSC), a pulse-width modulation scheme, and a measurement system. Real-time simulation outputs (stator currents and rotor speed) were validated under steady-state and transient conditions using as reference an experimental test bench based on a DTPIM with 15 kW-rated power. The accuracy of the proposed digital hardware implementation was evaluated according to the simulation and experimental results. Finally, statistical performance parameters were provided to analyze the efficiency of the proposed DTPIM hardware implementation method.

• 실천공학교육논문지
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• 제11권2호
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• pp.143-150
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• 2019

회로 이론은 전기 및 전자 공학 분야에서 가장 기본이 되는 다양한 회로의 해석과 설계를 체계화한 학문으로 회로 이론 교과목은 전기 및 전자 공학도라면 반드시 습득하도록 4년제 대학을 기준으로 학부 2학년에 한 학기 내지는 2 학기에 걸쳐 전공 교과목으로 편성되어 있다. 또한 학생들이 회로 이론에 대한 이해도를 높이고, 실제 회로를 구성한 실험을 통하여 회로 설계에 대한 기술 및 응용력을 습득할 수 있도록 하는 실험 교과목이 이론 교과목을 뒷받침하기 위해 동반 편성되고 있다. 본 논문에서는 회로 이론을 뒷받침하는 실험 교육에 대한 학습 효과를 높이기 위해 전기회로 설계 및 실험 교과목에서 시행하고 있는 수업 방법에 대한 사례 연구에 대해 기술한다. 이를 위해 이론 학습, 시뮬레이션, 실험 및 설계 프로젝트 등이 복합적으로 구성된 15주 수업 모형을 제안한다. 제시된 수업 모형에서는 이론을 보완하기 위한 시뮬레이션과 사전 실험 준비 과정이 강화되고, 공학 엔지니어로서의 실질적인 회로 설계 능력을 배양하기 위한 설계 프로젝트가 도입되어 운영된다. 5년 동안의 운영 결과는 제안된 모형이 효용성이 있음을 보여준다.

• 전기학회논문지
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• 제61권12호
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• pp.1944-1947
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• 2012

In this work, we investigated quench characteristics of matrix-type superconducting fault current limiters (MFCLs) according to the turn number of reactors. The reactors used in MFCLs apply magnetic field to superconducting elements within reactors when fault currents surge into MFCL systems. It makes the fast and simultaneous quenches between superconducting elements. Also reactors decrease the fault power burden of superconducting elements by bypassing the partial fault currents to itself, when quench occurs. These structure proposed in this work can be expected to achieve much more current limiting capacity even though it uses less superconductors compared with other type SFCLs. Three reactors were made by Bakelite. These reactors with the turn number of 190, 380 and 570, had the length of 270 mm and diameter of 80 mm. We reported experimental results, including fault currents, fault voltages and resistance in superconducting elements according to the turn number of reactors. We confirmed that experimental results will be useful in next future plan for the real power grid.

• 마케팅과학연구
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• 제17권2호
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• pp.99-110
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• 2007

The widespread use of self-service concepts in retailing has resulted in increased attention to the design of retail environments and to stimuli operating at the point of sale. One such merchandising technique, the "bundled presentation", i.e., related products are presented in close proximity to each other, is widely used by retailers but has rarely been investigated by academic consumer researchers. This study presents the results of a field experiment into the effects of presenting products in their usage context. Customers' attitudes towards the same product displayed in different ways are compared with each other. The results show that related products, i.e., products that are used together, should be presented in a coordinated display. Furthermore, the bundled presentation enhanced consumers' attitudes of the product when they saw it first in a bundled presentation and then evaluated it in front of a traditional presentation.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2005년도 하계학술대회 논문집 Vol.6
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• pp.215-216
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• 2005

To decrease and remove of much noises that is detected in PD (partial discharge) measuring test. we forced on detection of those. We made W-LC filter for measuring PD. which adapted that to field test. We tested after design laboratory circumstances like field line. and then the phase change properties of detected signal in UHF sensor were measured by Lemke Probe and oscilloscope (TDS-3054. Tektronix). Eventually we checked decrement of noises from experimental result. Also from experimental result at the joint box of 22.9[kV] distribution line. we obtained reasonable data which enable noises to decrease. Hereafter those results will be adapted at ultra-high voltage for trouble prevention and on-line cable watch. diagnosis of those.

• 한국정밀공학회지
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• 제25권5호
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• pp.89-95
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• 2008

The Acousto-Optic Tunable Filter (AOTF) is a high-speed full-field monochromator which generates two spectrally filtered light beams with ordinary and extraordinary polarization state. Thus, AOTF is widely used to build full-field spectral imaging system or spectral domain interferometer. However, AOTF has a big problem that the angle of diffracted light changes according to the scanning of wavelength, which makes image shift on CCD plane In this paper, we propose an analytic design of prism system to compensate the image shift. The detailed analysis of light paths in a prism and basic experimental results are presented to verify our proposed compensation method. The experimental results agree with simulation results based on suggested prism model and image shift is minimized at optimal condition. Also, it can be extended to compensate the image shift for ordinary and extraordinary polarized light simultaneously.

• Nuclear Engineering and Technology
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• 제51권5호
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• pp.1279-1288
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• 2019

The vortex-type fluidic diode (FD) is a key safety component for inherent safety in various advanced reactors such as the sodium fast reactor (SFR) and the molten salt reactor (MSR). In this study, topology optimization is conducted to optimize the design of the vortex-type fluidic diode. The optimization domain is simplified to 2-dimensional geometry for a tangential port and chamber. As a result, a design with a circular chamber and a restrictor at the tangential port is obtained. To verify the new design, experimental study and computational fluid dynamics (CFD) analysis were conducted for inlet Reynolds numbers between 2000 and 6000. However, the results show that the performance of the new design is no better than the original reference design. To analyze the cause of this result, detailed analysis is performed on the velocity and pressure field using flow visualization experiments and 3-D CFD analysis. The results show that the discrepancy between the optimization results in 2-D and the experimental results in 3-D originated from exclusion of an important pressure loss contributor in the optimization process. This study also concludes that the junction design of the axial port and chamber offers potential for improvement of fluidic diode performance.

• 한국전기전자재료학회논문지
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• 제25권4호
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• pp.253-260
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• 2012

IGBT (insulated gate bipolar transistor) have received wide attention because of their high current conduction and good switching characteristics. To reduce the power loss of IGBT, the on state voltage drop should be lowered and the switching time should be shorted. However, there is Trade-off between the breakdown voltage and the on state voltage drop. To achieving good electrical characteristics, field stop IGBT (FS IGBT) is proposed. In this paper, 1,200 V planar gate non punch-through IGBT (planar gate NPT IGBT), planar gate FS IGBT and trench gate FS IGBT is designed and optimized. The simulation results are compared with each three structures. In results, we optain optimal design parameters and confirm excellence of trench gate FS IGBT. Experimental result by using medici, shows 40% improvement of on state voltage drop.

• Journal of Power Electronics
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• 제16권2호
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• pp.805-814
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• 2016

Electric-field coupled power transfer (ECPT) systems have been proposed as an alternative wireless power transfer (WPT) technology in recent years. With the use of capacitive plates as a coupling structure, ECPT systems have many advantages such as design flexibility, reduced volume of the coupling structure and metal penetration ability. In addition, wireless communications are effective solutions to improve the safety and controllability of ECPT systems. This paper proposes a power and signal shared channel for electric-field coupled power transfer systems. The shared channel includes two similar electrical circuits with a band pass filter and a signal detection resistor in each. This is designed based on the traditional current-fed push-pull topology. An analysis of the mutual interference between the power and signal transmission, the channel power and signal attenuations, and the dynamic characteristic of the signal channel are conducted to determine the values for the electrical components of the proposed shared channel. Experimental results show that the designed channel can transfer over 100W of output power and data with a data rate from 300bps to 120 kbps.

• 센서학회지
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• 제31권2호
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• pp.120-124
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• 2022

With advancements in underwater stealth technology for naval vessels, new sensor configurations for detecting targets have been attracting increased attention. Latest underwater mines adopt multiple sensor configurations that include electric field sensors to detect targets and to help acquire accurate ignition time. An underwater electric field sensor consists of a pair of electrodes, signal processing unit, and preamplifier. For detecting underwater electric fields, the preamplifier requires low-noise amplification at ultra-low frequency bands. In this paper, the specific requirements for low-noise preamplifiers are discussed along with the experimental results of various setups of matched transistors and chopper stabilized operational amplifiers. The results showed that noise characteristics at ultra-low frequency bands were affected significantly by the voltage noise density of the chopper amplifier and the number of matched transistors used for differential amplification. The fabricated preamplifier was operated within normal design parameters, which was verified by testing its gain, phase, and linearity.