• 대한전기학회:학술대회논문집
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• 대한전기학회 1995년도 하계학술대회 논문집 A
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• pp.413-415
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• 1995

This paper presents a new approach in the design of multiple power output electronic ballasts for compact fluorescent lamps which power output range of 11W, 15W, 20W by using equivalent resistance and RLC equivalent circuit concept and frequency control. A multiple power output electronic ballast which adopts half-bridge inverter topology is set up to compare the results of PSpice simulation with experimental ones. Starting characteristics of lamp voltage, lamp current and light output are better than the existing electronic ballasts, and therefore is verified the validity of the proposed method.

• Journal of Power Electronics
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• 제4권2호
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• pp.102-111
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• 2004

This paper is concerned with a deadbeat current control implementation of shunt-type three-phase active power filter (APF). Although the one-dimensional deadbeat control method can attain time-optimal response of APF compensating current, one sampling period is actually required fur its settling time. This delay is a serious drawback for this control technique. To cancel such a delay and one more delay caused by DSP execution time, the desired APF compensating current has to be predicted two sampling periods ahead. Therefore an adaptive predictor is adopted for the purpose of both predicting the control error of two sampling periods ahead and bringing the robustness to the deadbeat current control system. By adding the adaptive predictor output as an adjustment term to the reference value of half a source voltage period before, settling time is made short in a transient state. On the other hand, in a steady state, THD (total harmonic distortion) of the utility grid side AC source current can be reduced as much as possible, compared to the case that ideal identification of controlled system could be made.

• 한국멀티미디어학회논문지
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• 제3권4호
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• pp.424-432
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• 2000

본 논문에서는 LCD 시스템에서 호스트와 LCD 컨트롤러사이의 인터페이스를 위한 새로운 데이터 코딩기법과 회로를 제안한다. 제안한 회로는 기존의 국제 표준으로 사용되고 있는 LVDS(Low Power Differential Signaling)를 수정한 회로와 데이터 천이 최소화를 위한 추가적인 직렬 데이터 코딩 기법으로 한 클럭에 2비트의 신호를 동시에 전송할 수 있다. 이에 따라 동작 주파수를 절반으로 줄일 수 있으며 differential signaling으로 전자파 장애와 전력소비 문제를 동시에 해결할 수 있다. 제안한 회로의 성능평가를 위하여 기존의 signaling기법과 전력 소비와 데이터 전송 속도 측면에서 비교 분석하였으며, 컴퓨터 시뮬레이션 결과를 통해 향상된 데이터 천이 감소율을 보임을 확인하였다.

• Journal of Electrical Engineering and Technology
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• 제13권4호
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• pp.1528-1538
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• 2018

In this paper, configuration of $1-{\phi}$ seven-level boost DC-link cascade based reversing voltage multilevel inverter (BDCLCRV MLI) is proposed for uninterrupted power supply (UPS) applications. It consists of three level boost converter, level generation unit and full bridge circuit for polarity generation. When compared with conventional boost cascaded H-bridge MLI configurations, the proposed system results in reduction of DC sources, reduced power switches and gate drive requirements. Inverter switching is accomplished by providing appropriate switching angles that is generated by any optimization switching angle techniques. Here, round modulation control (RMC) method is taken as the optimization method and switching angles are derived and the same is compared with various switching angles methods i.e., equal-phase (EP) method, and half-equal-phase (HEP) method which results in improved quality of obtained AC power with lowest total harmonic distortion (THD). Reduction in DC sources and switch count makes the system more cost effective. A simulation and prototype model of $1-{\phi}$ seven-level BDCLCRV MLI system is developed and its performance is analyzed for various operating conditions.

• 핵의학기술
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• 제12권3호
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• pp.192-198
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• 2008

Purpose: The scan time reduction helps to yield more accurate results and induce the minimization of patient's motion. Also we can expect that satisfaction of examination will increase. Nowdays medical equipment companies have developed various programs to reduce scan time. We used Onco. Flash (Pixon method, SIEMENS) that is an image processing technique gated cardiac blood pool scan and going to evaluate its clinical usefullness. Materials and Method: We analyzed the 50 patients who were examined by gated blood pool scan in nuclear medicine department of Asan Mediacal Center from June $20^{th}$ 2008 to August $14^{th}$ 2008. We acquired the Full-time (6000 Kcounts) and Half-time (3000 Kcounts) LAO image in same position. And we acquired LVEF values ten times from Full-time, Half-time images acquired by the image processing technique and analyzed its mean and standard deviation values. To estimate LVEF in same conditions, we set automatic location of the LV ROI and background ROI based on same X and Y-axis. Also we performed blinding tests to physician. Results: After making a quantitative analysis of the 50 patients EF values, each mean${\pm}$standard deviation is shown at Full-time image $68.12{\pm}7.84%$, Half- time (acquired by imaging processing technique) $68.49{\pm}8.73%$. In the 95% confidence limit, there was no statistically significant difference (p>0.05). After blinding test with a physician for making a qualitative analysis, there was no difference between Full-time image and Half-time image acquired by the image processing technique for observing LV myocardial wall motion. Conclusion: Gated cardiac blood pool scan has been reported its relatively exact EF measured results than ultrasound or CT. But gated cardiac blood pool scan takes relatively longer time than other exams and now it needs to improve time competitive power. If we adapt Half-time technique to gated cardiac blood pool scintigraphy based on this study, we expect to reduce possible artifacts and improve accessibility as well as flexibility to exam. Also we expect patient's satisfaction.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 추계학술대회 논문집 전기설비전문위원
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• pp.140-143
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• 2008

In this study, it was studied about the improved road light design for drivers and pedestrians using ray- or reverse ray-tracing method. Many of conventional road lights are not suitable for drivers and pedestrians because it has some serious problems such as glare effect or randomicity of illuminated areas. It was oriented from customary design method which was pointed at simple target such as luminance or electrical power. But it was not truth any more that the high luminance or electrical power consumption mean more bright and good mad light. We studied ray-tracing method for road light reflector design to get the several goals. It means that good road light has easy for drivers and Pedestrians eyes and illuminating objects on the road clearly. So, we set the design targets such as uniformity on the road area per one road light, shading angles and continuous luminance uniformity on the long distance road. We designed ideal road light conditions using ray-tracing method. We set the height of drivers and pedestrians eyes and calculated design guideline to make above design targets. Then we designed road light reflector using reverse ray-tracing method. And we achieved same luminance on the road almost half power consumption because we reduced loss of light. We achieved ideal design guide as 75 degrees of shading angles and 0.5 of luminance uniformity on the road area. Finally, we suggested reflector design for 250 watts power consumption CDM light source.

• 전기학회논문지P
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• 제58권3호
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• pp.347-350
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• 2009

In this study, it was studied about the improved road light design for drivers and pedestrians using forward or reverse ray-tracing method. Many of conventional road lights are not suitable for drivers and pedestrians because it has some serious problems such as glare effect or randomicity of illuminated areas. It was oriented from customary design method which was pointed at simple target such as luminance or electrical power. But it was not truth any more that the high luminance or electrical power consumption mean more bright and good road light. We studied ray-tracing method for road light reflector design to get the several goals. It means that good road light has easy for drivers and pedestrians eyes and illuminating objects on the road clearly. So, we set the design targets such as uniformity on the road area per one road light, shading angles and continuous luminance uniformity on the long distance road. We designed ideal road light conditions using ray-tracing method. We set the height of drivers and pedestrians eyes and calculated design guideline to make above design targets. Then we designed road light reflector using reverse ray-tracing method. And we achieved same luminance on the road almost half power consumption because we reduced loss of light. We achieved ideal design guide as 75 degrees of shading angles and 0.5 of luminance uniformity on the road area. It is superior than conventional road light ability such as 0.35 of luminance uniformity of 400 watts power consumption lamp. Finally, we suggested reflector design for 250 watts power consumption CDM Iight source.

• International Journal of Fuzzy Logic and Intelligent Systems
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• 제2권2호
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• pp.95-99
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• 2002

The Loose Part Monitoring System(LPMS) has been designed to detect. locate and evaluate detached or loosened parts and foreign objects in the reactor coolant system. In this paper, at first, we presents an application of the back propagation neural network. At the preprocessing step, the moving window average filter is adopted to reject the reject the low frequency background noise components. And then, extracting the acoustic signature such as Starting point of impact signal. Rising time. Half period. and Global time, they are used as the inputs to neural network . Secondly, we applied the neural network algorithm to LPMS in order to estimate the mass of loose parts. We trained the impact test data of YGN3 using the backpropagation method. The input parameter for training is Rising clime. Half Period amplitude. The result shored that the neural network would be applied to LPMS. Also, applying the neural network to thin practical false alarm data during startup and impact test signal at nuclear power plant, the false alarms are reduced effectively.

• Journal of Welding and Joining
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• 제33권1호
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• pp.87-93
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• 2015

This study was performed to develop repair technology for J-Groove dissimilar metal weld of pressurizer heater sleeve in nuclear power plants. Pad, J-Groove automatic welding and mechanical machining equipments to develop repair technology using 'Half Nozzle Repair' were designed and manufactured. To obtain the optimum welding process parameters during Pad temperbead overlay welding, several welding experiments using Taguchi method were conducted. Weldability of Pad overlay weld specimens was estimated by PT/RT test, FE-SEM, EDS and Vickers hardness test. Also, J-Groove welding to adjust weld shape conditions requiring in ASME Code was carried out and its integrity of weld specimens was evaluated through PT/RT test and optical microscope. Consequently, it was revealed that Pad and J-Groove overlay welding for dissimilar metal weld of pressurizer heater sleeve could be possible to meet Code standard without weld defect.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.297-300
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• 2001

The SMZ half-bridge converter uses the resonance between the inductance of transformer and the resonant capacitances to transfer the input power to the load. In addition to this kind of characteristic of the converter, there are some features such as the capability of soft switching operation, a lower switching loss, and a higher power density in the converter. However in the low-voltage and high-output current applications of the converter, the extremely increased output ripple voltage prevents the converter from normal operation. In order to overcome the drawback of the converter, adding the output filter inductor to the converter, the converter shows the completely different resonant characteristics. In this paper, We analyzed the resonant characteristics of the SMZ converter with the output filter inductor and investigated what the analyzed results affect the converter operation. The experiment of a I50W prototype SMZ converter with 5V output and 310V input is carried out to verity the validity of the analyzed results.