• 한국소음진동공학회논문집
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• 제18권9호
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• pp.937-942
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• 2008

이 논문은 건설이 완료된 700MW급 발전소의 시운전 기간 중 주 급수펌프 임펠러에서 반복적으로 발생된 웨어링 이탈 및 고착, 슈라우드 손상 그리고 축 절단 등의 절손이 부분부하 조건에서 증폭되는 압력맥동과 연관이 있는 것으로 규명되었다.

• 한국컴퓨터산업학회논문지
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• 제2권4호
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• pp.565-572
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• 2001

최근 고체 레이저 출력측에 비선형 광학재료를 설치하여 적외선에서 자외선에 이르기까지 넓은 대역의 파장을 가진 레이저광이 요구된다. 비선형 광학소자는 고조파발생기와 파라메터 발생기와 같은 레이저원을 이용한 주파수 전 영역까지 확장 할 수가 있다. 주파수 변환은 고전력 레이저를 이용한 확장기술에 많이 이용하고있다. 새로운 각 주파수 대역에서 광학 매개체의 비선형 광학의 응답 등을 이용할 수가 있다. 이러한 과정들은 자외선영역에서 적외선까지 고전력 방사발생을 이용할 수가 있다. 광학 파라메터발생기와 증폭기는 저주파수에서 2가지 파장 등을 발생한다. 싱글 주파수원으로부터 발생하여 몇몇의 경우에는 가시광선 영역에서 거의 자외선 영역까지 이용할 수가 있다. 결과적으로 녹색광을 얻기 위해서, 펄스형Nd:YAG 레이저는 다단펄스 포밍회로를 이용하였고 비선형광학(KTP)소자를 채택하여 적용하였다. 따라서 본 연구에서는 펄스 중첩법을 이용하여 기본파로서 직접 설계 제작 후 SHG 장치를 장착하여 녹색광을 얻고 각 중첩 메쉬에 같은 에너지를 인가했을 때의 레이저 출력과 녹색광 출력간의 상관관계와 메쉬 수에 따른 변환효율을 조사하였다.

• 한국콘텐츠학회논문지
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• 제14권5호
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• pp.8-17
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• 2014

슈퍼컴퓨팅 자원들은 주로 MPI와 같은 메시지 교환 인터페이스에 기반한 통신 집적도가 높은 고성능 컴퓨팅(HPC: High Performance Computing) 응용 분야를 지원하는데 활용되어 왔다. 반면에, 대규모 계산처리 컴퓨팅(HTC: High Throughput Computing) 방식의 패러다임은 주로 계산 집적도가 높고(상대적으로 적은 I/O 연산), 독립적인(작업들 간의 통신이 적음) 많은 수의 작업을 처리하는 것을 요구하고 있다. 국내에서도 고에너지 물리, 신약개발, 핵물리와 같은 연구 분야를 중심으로 대규모 컴퓨팅 자원을 요구하는 계산처리에 대한 수요가 증가하고 있다. 본 논문에서는 이러한 HTC 과학 응용들에 대한 효율적인 지원을 국가차원의 슈퍼컴퓨팅 분산 환경에서 제공하기 위해 연구/개발되어진 대규모 계산처리 서비스(HTCaaS: High Throughput Computing as a Service)의 전체 구조 및 구성 요소, 실행 시나리오 및 실제 응용 적용 사례 등에 대해 서술한다.

• 한국강구조학회 논문집
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• 제24권6호
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• pp.647-657
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• 2012

원자력 배관 시스템은 엄격한 설계기준에 따라 제작 되었음에도 불구하고, 장기 사용에 따라 발생하는 감육 및 균열에 의한 파손 사례가 보고되고 있다. 이에 본 연구에서는 스테인리스강 배관 시험체의 단조하중 및 반복하중 재하실험을 실시하여 국부 감육과 균열의 손상유무 및 0%, 35%, 75%의 손상정도가 배관의 파괴거동에 미치는 영향을 실험적으로 검토하였다. 본 실험에서는 실제 원자력 발전소에서 사용되고 있는 직경 3인치 TP316 스테인리스강 엘보우와 직관 배관을 대상으로 하여, 인위적으로 곡관부와 용접부에 0%, 35%, 75%의 국부적인 감육과 균열을 도입하고 20MPa의 내압을 가한 후 재하실험을 실시하였다. 그 결과, 국부 감육 및 균열의 손상정도가 파괴모드, 최대하중, 반복회수 및 에너지흡수율에 미치는 영향을 정량적으로 평가하였다. 그리고 휨 모멘트를 이용하여 ASME의 결함 허용기준을 평가하였다.

• The Korean Journal of Physiology
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• 제9권2호
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• pp.33-39
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• 1975

Changes of urinary aldosterone excretion, concurrent sodium and potassium excretion following furosemide administration were studied in normotensive young Korean with high sodium intake, moderate sodium restriction and marked sodium depletion. After intravenous injection of furosemd 40mg, plasma and urine samples were collected at every thirty minutes for two hours. Plasma-and urinary aldosterone, electrolyte concentration and urine flow rate were measured by means of radioimmunoassay or flamephotometry. Relations of urinary aldosterone to concurrent sodium or potassium/sodium ratio, and of urinary aldosterone to concurrent plasma aldosterone activity were studied. Following were the results: 1. Furosemide administration resulted in a increased urinary aldosterone concentration and unchanged or somewhat decreased sodium concentration in course of time after the injection. 2. Urinary potassium concentration showed initial decrease and subsequent increase in course of time after furosemide administration and it resulted in a gradual increase in urinary potassium/sodium ratio. 3. Studying the relations between urinary aldosterone excretion and potassium/sodium excretion ratio, or sodium excretion were meaningless because of the urinary flow rate after the injection was decreased with time course. 4. Furosemide administration showed a good relationship of urinary aldosterone concentration to concurrent potassium/sodium ratio rather than concurrent sodium concentration in subjects with sodium restriction, but no meaningful relationship was detected in subjects with high sodium intake because increasing rate of the ratio was not so wide. 5. Furosemide also resulted a reasonable relation of plasma aldosterone concentration to concurrent urinary aldosterone concentration especially during low sodium intake. 6. Above results suggested that relation of urinary aldosterone concentration to K/Na ratio following furosemide administration during sodium restriction is significant and has a benefit to reduce the variation induced by kalemic change showing in the diragram for daily aldosterone to sodium excretion.

• 한국식생활문화학회지
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• 제17권2호
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• pp.141-152
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• 2002

This study provides a national examination on youths' 'understanding' of irradiated food. The 1,200 subjects of the survey were randomly sampled from male and female students throughout the nation, between grades five and eleven. The survey was conducted toward these samples in November 2000. The number of respondents with exposure to irradiated food was so small, amounting to only 4.0 percent of the whole sample. The core concept used in this study is 'impression'. An impression is information about a specific subject, which carries significance to an individual. The results show that the higher the grade was, the more value the contents of impression contained. Furthermore, impressions concerning atomic or nuclear energy, and radioactivity increased greatly among students in middle school and above. Providing information of effects and advantages of irradiated food was focused to increase positive impressions and decrease the negative ones more greatly than providing simple factual information. Youths showed less value-centered impressions of irradiated food and more impressions centered on fragmented facts than adults. Respondents previously exposed irradiated food were shown to acquire the most of their information from the television and newspaper media. Among six information sources presented in the survey, youths pointed out 'science and technology research institutes' as the most credible. International organizations and environmental/ consumer organizations were evaluated as having relatively high credibility. Providing simple factual information of irradiated food did not seem to bring about any difference to the intention of purchasing irradiated food. On the other hand, respondents provided with effects-included information showed an increase in such intention. Our research results of the youth show a notable difference with that of the adults. Thus, programs and strategies to enhance youths' understanding should differ from those concerning adults.

• 한국안전학회지
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• 제32권3호
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• pp.90-98
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• 2017

The purpose of this study was to examine the effect of employment type(direct employment, dispatch and service supplier) on risk factor exposure, health and satisfaction. The data of the 4th wave of Korean Working Conditions Survey (KWCS) conducted by Korea Occupational Safety and Health Agency (KOSHA) in South Korea was used. Business support service industry and manufacturing industry were selected as appropriate industries for analysis. In the final analysis, 5,865 in the manufacturing industry and 1,361 in the service support industry were included. Various variables related risk, safety, satisfaction and health such as risk factor exposure, MSDs exposure, work environment satisfaction, injury probability, dangerous work, workload, physical health problem, perceived health, positive emotions, stress, participation for decision making and experience of accident/disease were analyzed and company size and age was controled. An ANCOVA was conducted to identify significant mean differences of risk, safety, satisfaction and health related variables among direct employed workers, dispatch and service supplier workers. The results showed that all the variables except stress showed a significant difference depending on employment type in the service supply industry. In the manufacturing industry, there were significant difference in the risk factor exposure, MSDs exposure, work environment satisfaction, workload, physical health problem, perceived health, and participation depending on employment type. These results indicated that the risks are unloaded to subcontract and outsourcing company workers. Based on these results, the implications of this study and suggestions for future research were discussed.

• 방사성폐기물학회지
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• 제12권4호
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• pp.335-344
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• 2014

우리나라 중 저준위 방사성폐기물의 처분시설개발을 위해 Safety Case 종합프로그램을 구축하였다. Safety Case 종합프로그램은 단계별 처분시설 종합개발을 위한 안전성판단과 계획수립을 목적으로 IAEA 등 국제기준을 참고하여 국내 환경에 적합하도록 구축하였다. 처분시설 종합안전성 확보체계는 최적화전략, 강건성전략, 논증가능성전략 및 심층방어전략에 따라 안전목표와 안전원칙을 만족하도록 구성하였다. 처분시설의 안전성은 평가기반의 품질에 따라 불확실성 저감을 위한 단계별 안전성평가와 안전성 수준의 확인 및 의사결정판단을 위한 다양한 신뢰성증진을 통해서 확보하도록 하였다.

• 한국신뢰성학회지:신뢰성응용연구
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• 제18권3호
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• pp.271-279
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• 2018

Purpose: Probabilistic safety analysis was performed to enhance the safety and reliability of nuclear power plants because traditional deterministic approach has limitations in predicting the risk of failure by crack growth. The study introduces a probabilistic approach to establish a basis for probabilistic safety assessment of passive components. Methods: For probabilistic modeling of fatigue crack growth rate (FCGR), various FCGR tests were performed either under constant load amplitude or constant ${\Delta}K$ conditions by using heat treated X-750 at low temperature with adequate cathodic polarization. Bayesian inference was employed to update uncertainties of the FCGR model using additional information obtained from constant ${\Delta}K$ tests. Results: Four steps of Bayesian parameter updating were performed using constant ${\Delta}K$ test results. The standard deviation of the final posterior distribution was decreased by a factor of 10 comparing with that of the prior distribution. Conclusion: The method for developing a probabilistic crack growth model has been designed and demonstrated, in the paper. Alloy X-750 has been used for corrosion fatigue crack growth experiments and modeling. The uncertainties of parameters in the FCGR model were successfully reduced using the Bayesian inference whenever the updating was performed.

• 한국분말재료학회지
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• 제11권4호
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• pp.308-313
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• 2004

An experimental study on the combustion of superfine aluminum powders (average particle diameter, a$_{s}$: ∼0.1 ${\mu}{\textrm}{m}$) in air is reported. The formation of aluminum nitride during the combustion of aluminum in air and the influence of the combustion scenario on the structures and compositions of the final products are in the focus of this study. The experiments were conducted in an air (pressure: 1 atm). Superfine aluminum powders were produced by the wire electrical explosion method. Such superfine aluminum powder is stable in air but once ignited it can burn in a self-sustaining way due to its low bulk: density (∼0.1 g/㎤) and a low thermal conductivity. During combustion, the temperature and radiation were measured and the actual burning process was recorded by a video camera. Scanning electron microscopy (SEM), X-ray diffraction (XRD) and chemical analysis were performed on the both initial powders and final products. It was found that the powders, ignited by local heating, burned in a two-stage self-propagating regime. The products of the first stage consisted of unreacted aluminum (-70 mass %) and amorphous oxides with traces of AlN. After the second stage the AlN content exceeded 50 mass % and the residual Al content decreased to ∼10 mass %. A qualitative discussion is given on the kinetic limitation for AlN oxidation due to rapid condensation and encapsulation of gaseous AlN.N.