• Proceedings of the KIEE Conference
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• summer
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• pp.971-973
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• 2004

본 논문에서는, 초고압 GIS(Gas Insulated Switchgear)용 GCB(Gas Circuit Breaker)의 3상 배치구조 설계를 위한 상간, 극간, 대지간의 절연성능을 평가하였다. 뇌임펄스 전압과 상용주파 전압인가 시 상간, 극간, 대지간의 절연설계 기준을 근거로 절연설계 안전율을 고려하여 설계에 적용하였다. 수치적 전계 해석법으로 3차원 전계 해석법과 2차원 축대칭 해석법을 이용하였으며 절연설계 여유율과 현장에서의 절연파괴 시험을 통한 데이타와 비교 분석하였으며, 분석한 결과 절연설계 기준에 적합한 상배치 구조 설계임을 확인하였다.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.40-41
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• 2007

송전선로 선로정수는 전력계통 운영 Data 파일의 중요요소로서 정상분, 영상분, 임피던스 및 어드미턴스가 있다. 이들 선로정수는 계산프로그램을 이용하여 산출 활용하고 있으며 발변전소 준공시험시 정수 실측값은 참고자료로 활용하였다. 기존의 전압을 인가하여 측정한 전압강하법으로는 유도전압의 영향으로 운전중인 변전소에서는 측정이 불가하였으나 신규 도입한 선로정수 측정장비는 전류를 회로의 주입하여 이때 발생하는 전압을 측정하는 방법으로 전류원의 주파수 가변이 가능하여 상용주파수의 유도전압대역을 피해가면서 측정할 수 있는 장점이 있다. 이러한 측정장비들의 발달로 계산값과 실제 측정값과의 차이를 확인, 분석하고자 선로정수를 실측하게 되었다.

• Proceedings of the KIEE Conference
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• 1993.07b
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• pp.1016-1019
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• 1993

A low-pass L-C filter has been adopted for conversion of frequency variable 3 phase PWM waveform to a grid power line and it is used for attenuation of harmonics in the VSI PWM Inverter. A optimum design of the L, C parameters was derived. The result of the study show that the inductor L seems to have a certain air gap for linear I-V characteristics and the resonant frequency of the filter must be set below the 5th harmonics of the grid power line. Further, the voltage drop in L must be within a adequate limit compared to grid power voltage.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.11a
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• pp.667-673
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• 2000

A number of issues related with the vibrational behavior of pretwisted rotating beams featuring anisotropic properties and incorporating adaptive capabilities are considered in this paper. The adaptive capabilities are provided by a system of piezoactuators bonded or embedded into the structure. Based on the converse piezoelectric effect and on the out of phase activation, boundary control moments are pizoelectrically induced at the beam tip. A feedback control law relating the induced bending moments with the kinematical response quantities appropriately selected is used, and its beneficial effects, considered in conjunction with that of the beam anisotropy and structural pretwist upon the eigenvibration characteristics are highlighted

• Proceedings of the Korea Information Processing Society Conference
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• 2023.11a
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• pp.27-29
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• 2023

폰노이만 구조를 따르는 기존의 컴퓨터 시스템은 프로세서와 메모리의 역할이 구분되어 있으며 프로세서는 메모리에 저장된 명령어와 데이터를 불러와 실행한다. 이 과정에서 메모리와 프로세서 간에 발생하는 데이터 이동은 메모리 집약적인 응용을 처리하는데 있어서 심각한 오버헤드를 야기할수 있다. PIM(Processing-In-Memory)은 데이터 이동 병목을 해결하기 위해서 메모리에 프로세서의 능력을 통합하는 기술로서 최근의 메모리 기술의 발전으로 주목받고 있다. 본 논문에서는 UPMEM사의 상용 PIM 제품을 기반으로 몬테카를로 방법을 이용한 원주율 추정을 구현하고 성능 확장성을 분석하였다.

• Journal of Food Hygiene and Safety
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• v.6 no.3
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• pp.139-145
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• 1991

In order to observe the Na contents, Korean common foods, especially processed foods were analyzed by Atomic Absorption Spectrophotometer. 1. The Na contents of instant noodle (ramen) was 400-900 mg/100 g and Na contents of their soup powder was 10000-16000 mg/100 g. 2. The Na contents of corns and beans was very low but their processed foods, com Dake and soybean milk, had relatively high Na contents. 3. The Na contents of meats was 40-60 mg/100 g but the Na contents of meats products was 700-900 mg/100 g. 4. The Na contents of Davoring salt was 12000-38000 mg/100 g, those of soybean products was 3000-6OOO mg/100 g, and that of seasoning MSG was 8000-17000 mg/100 g. 5. There was no statistical difference between the results of wet ash method and dry ash method in the Na contents of all food groups.

• Proceedings of the Korean Society of Computer Information Conference
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• 2014.07a
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• pp.293-296
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• 2014

본 논문에서는 예측사격과 난전을 통하여 논스톱 액션을 추구하는 게임서버를 구현한다. 게임 서버를 구현하기 위하여 상용 엔진인 ProudNet과 Unity3D를 사용했으며, ProudNet은 강력한 상용 네트워크 엔진이며 Unity3D와 쉽게 데이터 통신을 할 수 있게 해준다. 클래스 다이어그램과 구성도를 통하여 예측 사격과 난전을 통하여 논스톱 액션을 추구하는 게임 서버 개발 방법을 제안한다.

• Korean Chemical Engineering Research
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• v.59 no.3
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• pp.333-338
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• 2021

The durability of the PEMFC stack for large commercial vehicles should be more than 5 times that for passenger vehicles. If the Chemical Accelerated Stress Test (AST) of PEMFC(Proton Exchange Membrane Fuel Cells) membrane for passenger cars is applied as it is for large commercial vehicles, there is a problem that the AST time becomes more than 2,500 hours. In order to shorten the AST time of DOE (Department of Energy), the chemical durability of the polymer membrane was evaluated using oxygen instead of air as a cathode gas. In this study, Nafion XL was used as a polymer membrane to evaluate accelerated durability under OCV, 90?, RH 30%, H₂/(air or oxygen) conditions. Among the DOE membrane durability target criteria, the decrease rate of short resistance was the fastest. By using oxygen instead of air, the degradation rate of the polymer membrane was accelerated while being less affected by electrode deterioration, reducing the polymer membrane durability evaluation time to less than half.

• The Journal of the Acoustical Society of Korea
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• v.41 no.3
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• pp.278-286
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• 2022

In this study, a 33-mode Free-Flooded Ring (FFR) transducer was designed to apply piezoelectric single crystal PIN-PMN-PT, which has high piezoelectric constants and electromechanical coupling coefficient. To ensure low-frequency high transmitting sensitivity characteristics with a small size of FFR transducer, the commercial FFR transducer based on piezoelectric ceramics was compared. To develop the FFR transducer with broadband characteristics, a piezoelectric segmented ring structure inserted with inactive elements was applied. The oil-filled structure was applied to minimize the change of acoustic characteristics of the ring transducer. It was verified that the transmitting voltage response, underwater impedance, and beam pattern matched the finite element numerical simulation results well through an acoustic test. The difference in the transmitting voltage response between the measured and the simulated results is about 1.3 dB in cavity mode and about 0.3 dB in radial mode. The fabricated FFR transducer had a higher transmitting voltage response compared to the commercial transducer, but the diameter was reduced by about 17 %. From this study, it was confirmed that the feasibility of a single crystal-applied FFR transducer with compact size and high-power characteristics. The effectiveness of the performance prediction by simulation was also confirmed.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.40 no.3
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• pp.194-202
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• 2003

To convert printed images into electronic ones automatically, it requires region analysis of document images and character recognition. In these, regional analysis segments document image into detailed regions and classifies thee regions into the types of text, picture, table and so on. But it is difficult to classify the text and the picture exactly, because the size, density and complexity of pixel distribution of some of these are similar. Thu, misclassification in region analysis is the main reason that makes automatic conversion difficult. In this paper, we propose region analysis method that segments document image into text and picture regions. The proposed method solves the referred problems using one dimensional median filter based method in text and picture classification. And the misclassification problems of boldface texts and picture regions like graphs or tables, caused by using median filtering, are solved by using of skin peeling filter and maximal text length. The performance, therefore, is better than previous methods containing commercial softwares.