• 전기학회논문지
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• 제57권10호
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• pp.1822-1828
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• 2008

This paper presents design parameter calculation methodology and its realization to construction for the 10/350${\mu}s$ lightning impulse current generator(ICG) modelled as double exponential function waveform with characteristic parameters ${\alpha},{\beta}$. Matlab internal function, "fzero" was applied to find ${\lambda}={\alpha}/{\beta}$ which is solution of nonlinear equation linearly related with two wave parameter $T_1$ and $T_2$. The calculation results for 10/350${\mu}s$ lightning impulse current show very good accuracy with error less 0.03%. Two type of 10/350${\mu}s$ ICGs based on the calculated design circuit parameters were fabricated by considering the load variation. One is applicable to the MOV based Surge protective device(SPD) for less 15 kA and the other is to test small resistive devices such as spark gap arrester and bonding device with maximum current capability 30 kA. The tested waveforms show error within 10% in comparison with the designed estimation and the waveform tolerance recommended in the IEC 61643-1 and IEC 60060-1.

• Journal of the Korean Data and Information Science Society
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• 제20권5호
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• pp.857-867
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• 2009

본 연구는 학년 (연령) 진급에 따른 인구증감률에 대하여 전국 학생수를 예측하는 다양한 방법들을 제시하고, 제시된 예측 모형들을 이용하여 출생아들이 고3학생이 되는 18년 후인 2026까지의 학생수를 예측하는 것이다. 이동평균과 시계열모형, 회귀분석 등 다양한 예측모형들이 사용되었고, 적합 척도들을 이용하여 이들의 오차들을 측정하였다. 예측오차를 측정하는 도구들을 기준으로 제시된 예측방법들 중 이동평균에 의한 방법은 쉽고 단순한 장점을 지니면서도 기존에 예측되어진 한국교육개발원의 예측결과 뿐 아니라 회귀분석 및 시계열예측의 고등기법들의 결과들 보다 예측 능력이 우수한 것으로 나타났다.

• Nuclear Engineering and Technology
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• 제38권2호
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• pp.155-162
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• 2006

It is necessary to monitor periodically the operability of safety-related motor-operated valves (MOVs) in nuclear power plants. However, acquiring diagnostic signals for MOVs is very difficult, and doing so requires an excessive amount of time, effort, and expenditure. This paper introduces an accurate and economical method to evaluate the performance of MOVs remotely. The technique to be utilized includes electrical measurements and signal processing to estimate the motor torque and the stem thrust, which have been cited as the two most effective parameters in diagnosing MOVs by the US Nuclear Regulatory Commission. The motor torque is calculated by using electrical signals, which can be measured in the motor control center (MCC). Some advantages of using the motor torque signature over other signatures are examined. The stem thrust is calculated considering the characteristics of the MOV and the estimated motor torque. The basic principle of estimating stem thrust is explained. The developed method is implemented in diagnostic equipment, namely, the Motor Operated Valve Intelligent Diagnostic System (MOVIDS), which is used to obtain the accuracy of and to validate the applicability of the developed method in nuclear power plants. Finally, the accuracy of the developed method is presented and some examples applied to field data are discussed.

• 한국추진공학회지
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• 제21권4호
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• pp.28-35
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• 2017

액체 추진 로켓 엔진에서 연소실로 향하는 산화제 공급은 연소기 산화제 개폐밸브에 의해서 제어된다. 산화제의 안정적인 공급을 위하여 밸브가 열려있을 때의 유량조건을 만족해야 할 뿐만 아니라, 산화제 공급라인의 예냉을 위해 밸브가 닫혀있을 때에도 요구되는 유량조건을 만족해야 한다. 본 연구에서는 연소기 산화제 개폐밸브의 재순환 유량특성을 확인하기 위한 시험을 수행하였고, 밸브 내부에 작용하는 힘평형 관계식을 이용하여 극저온 수명시험 이후 스프링 상수가 변화하는 경향을 확인하였다.

• 전기학회논문지
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• 제57권12호
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• pp.2255-2262
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• 2008

This paper presents a design parameter calculation methodology and its realization to construction for the damped oscillatory impulse current generator(ICG) modelled as damping factor $\alpha$. Matlab internal functions, "fzero" and "polyfit" are applied to find a which are solutions of second order nonlinear equation related with three wave parameters $T_{1},T_{2}$ and $I_{os}$. The calculation results for standard impulse current waveforms such as 4/10${\mu}s$, 8/20${\mu}s$ and 30/80${\mu}s$ show very good accuracy and this results make it possible to extend to generalization in the design of damped oscillatory lCG with any capacitor. 8/20${\mu}s$ ICG based on the calculated design circuit parameters is fabricated in consideration of the nonlinear load(MOV) variation. Comparisons of the tested waveforms with the designed estimation show error within 10% for the waveform tolerance recommended in IEC 60060-1 and IEEE std. C62.45.

• 해양환경안전학회지
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• 제7권3호
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• pp.93-106
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• 2001

Whether a ship is sub-standard or not shall be finally decided by the minimum standards laid down in international conventions or national standards having the same effects. The flag State is primarily responsible for implementing these standards as far as its own ships are concerned. And the port State shall, in the exercise of its rights under international law, take appropriate measures (including detention of ships identified as sub-standard), which are regarded as port State's supplementary role aiming at implementing these standards. The international standards are implemented by the regional co-operation in the form of the MOU(Memorandum of Understanding) on Port State Control in the Asia-Pacific Region on the ground that the PSC enforcement of only one country does not enable the eradication of sub-standard ships. Recently, EQUASIS which is an international database covering the whole world fleet change the regionalism of PSC into the globalization of PSC. However, there are many problems in Tokyo MOV and Korean PSC regime. In order to ensure the implementation of the standards laid down in international conventions and Tokyo MOU, the Korean and other country in Asia-Pacific shall settle the alienation from the actuality of the law, namely the problem of maritime administrative structure of non unifying PSC affairs.

• 조명전기설비학회논문지
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• 제24권2호
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• pp.69-76
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• 2010

본 논문은 SPD에 사용되는 배리스터에 대한 성능을 개선하기 위해 저압 배전계통에 사용하는 ZnO 배리스터의 소자 표면에 온도감응 소재를 도포한 것을 내장한 SPD의 신뢰성과 안정성을 개선하였다. '열폭주 방지 기능을 내장한 배리스터'설계를 통해 SPD내에 장착 시 열 보호기능의 단로기의 기능에 대한 trade-off 관계해석(trade-off:단로기에 단일펄스피크전류(ITM), 다중펄스피크전류(ITSM)에 대한 신뢰성과 배리스터 소자의 열화 및 수명한계에 따른 열폭주 현상을 예방하기 위한 단로기의 안정성 확보를 위한 최적의 설계)을 통해 신뢰성과 안정성을 확보하였고 열 보호기능을 배리스터 내부에 적용하여 SPD제작시 소형/경량화가 가능하도륵 하였다.

• 한국압력기기공학회 논문집
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• 제9권1호
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• pp.15-19
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• 2013

The auxiliary feedwater is an important to remove the heat from the reactor core when the main feedwater system is unavailable. In most initiating events in Probabilistic Safety Assessment(PSA), the operaton of this system is required to mitigate the accidents. For one of domestic nuclear power plants, a design change of a turbine-driven auxiliary feedwater pump(TD-AFWP), pipe, and valves in the auxiliary system is implemented due to the aging related deterioration by long time operation. This change includes the replacement of the TD-AFWP, the relocation of some valves for improving the system availability, a new cross-tie line, and the installation of manual valves for maintenance. The design modification affects the PSA because the system is critical to mitigate the accidents. In this paper, the safety effect of the change of the auxiliary feedwater system is assessed with regard to the PSA view point. The results demonstrate that this change can supply the auxiliary feedwater from the TD-AFWP in the accident with the motor-driven auxiliary feedwater pump(MD-AFWP) unavailable due to test or maintenance. In addition, the change of MOV's normal position from "close" to "open" can deliver the water to steam generator in the loss of offsite power(LOOP) event. Therefore, it is confirmed that the design change of the auxiliary feedwater system reduces the total core damage frequency(CDF).

• 한국컴퓨터정보학회논문지
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• 제17권10호
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• pp.11-23
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• 2012

본 논문에서는 OpenRISC 프로세서의 코드 크기를 저감하는 새로운 압축 명령어 집합 구조를 제시한다. 새로운 명령어와 형식은 기존 명령어들의 사용 빈도와 용법에 대한 프로파일 정보에 의해 결정된다. 제시된 기법에서는 기존의 32비트 명령어들과 연속적인 명령어들을 각각 대체하는 새로운 16비트 명령어와 32비트 명령어를 도입한다. 제시된 명령어는 세 유형으로 분류할 수 있다. 첫 번째는 사용 빈도가 높은 기존의 덧셈, 로드, 저장, 분기 명령어 등의 32비트 명령어들을 대체하는 새로운 16비트 명령어들이다. 두 번째 유형은 사용 빈도가 높은 두 개의 연속적인 로드 명령어, 두 개의 연속적인 저장 명령어, 32비트 데이터 이동 명령어를 압축하는 새로운 32비트 명령어들이다. 마지막으로 함수 프롤로그와 에필로그 명령어들을 각각 하나로 압축하는 두 개의 새로운 32비트 명령어가 제시된다. 추가된 명령어들을 디코딩하기 위해서 OpenRISC 하드웨어 디코더 부분이 확장된다. OpenRISC 1200프로세서에서 실험을 수행한 결과, 성능 저하 없이 30.4%의 코드 크기를 절감한다.

• The Plant Pathology Journal
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• 제22권2호
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• pp.155-160
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• 2006

A strain of Pepper mottle virus (PepMov) was isolated from chili pepper plants in Korea. In host range study, this virus, designated PepMoV-SNU1, shared most characteristics with PepMoV isolates reported previously. Thermal inactivation point ($45^{\circ}C\;to\;75^{\circ}C$) and dilution end point ($10^{-1}\;to\;10^{-4}$) of PepMoV-SNU1 showed differences depending on the propagation hosts. Cylindrical and pinwheel-shaped inclusions were always observed in pepper leaf tissues infected with the virus alone. Unexpectedly, a special structure of pinwheel shaped inclusion surrounded with unknown small spots was also observed in the leaf section when co-infected with a strain of pepper mild mottle virus. The partial sequence of coat protein gene and 3' untranslated region of PepMoV-SNU1 showed 98% identity with those of other PepMoV isolates. A primer pair derived from 3' end of the coat protein gene and poly A tail regions were designed. Optimal detection condition of PepMoV-SNU1 by RT-PCR was tested to determine appropriate annealing temperature and additional volumes of oligo-dT (18-mer), dNTP, and Taq polymerase. Under the optimized condition, an expected 500 Up PCR-product was detected in pepper leaves infected with PepMoV-SNU1 but not in healthy plants.