• 방사성폐기물학회지
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• 제15권4호
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• pp.355-367
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• 2017

2017년 6월에 영구정지 된 고리 1호기의 해체는 한국의 상업 원전에 대한 첫 해체 사례가 될 것이다. 해체 과정 중에 발생하는 폐기물에 대한 처분은 전체 해체 비용의 많은 부분을 차지한다. 따라서 방사화 및 오염된 콘크리트 구조물은 적절한 해체전략을 수립하여 경제적이고 안전하게 해체되어야 한다. 본 논문에서는 생물학적 차폐체에 대한 최적화된 해체 및 처분 시나리오를 연구하였다. 해체사례, 폐기물 처분 규정 및 처리 기술을 분석하였다. 그리고 생물학적 차폐체 제거 과정의 폐기물 발생량을 최소화하기 위해서, 최적 해체 시나리오를 제시하였고 폐기물 처분 방안을 도출하였다.

• 한국안전학회지
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• 제33권5호
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• pp.141-149
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• 2018

In a PCB factory, there is a corrosive chemical substance supply system that can causes major leakage accidents. These accidents can give rise to shut down the factory and do residents damage that cause enormous loss of properties. To mitigate these risks, it is necessary to provide a chemical disaster prevention system. Moreover, after considering the situation and environment of the production site, it is of great importance to build an optimal chemical accident prevention system by reflecting risk reduction measures from the point of process design and by assessing quantitative risk based on reliability data. However, because there was no established database of the reliability about facilities and equipment that can be used in the domestic, the business site and consulting organization had being used the reliability data such as USA CCPS(Center for Chemical Process Safety). In these days, Korean institutes are studying on reliability data utilization method of quantitative risk assessment for preventing chemical accidents and domestic utilization algorithms and storage bed of reliability data. This study presents samples of reliability database about the chemical substance supply system that constructed from the history data such as failure, maintenance for 10 years at a PCB factory. Also, this work proposes the safety design criteria for supply facilities of corrosive chemical substance by assessing quantitative risk on the basis of the reliability data.

• 정보처리학회논문지D
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• 제11D권7호
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• pp.1499-1506
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• 2004

본 논문에서는 화상 채팅에 대한 실태 분석, 접속 형태 분석 그리고 이외 음란성을 기술적으로 차단하기 위한 방법론을 제안하고자 한다. 현재 음란사이트를 차단하기 위한 기술적 방법은 있지만 화상 채팅에 있어 음란 행위를 선택적으로 차단하기 위한 기술적 해결 방안은 없는 실정이다. 기존의 음란사이트 차단 방법은 목록 기반과 단어 기방 방법인바 이는 그 내용이 처음부터 끝까지 무조건적으로 차단해야 하는 음란사이트 차단에는 적합한 방법이다. 그러나 화상 채팅사이트는 개설되어 있는 채팅방중에 음란성을 가지는 즉, 문제가 되는 채팅방만 선택적으로 차단을 해야하기 때문에 기존의 방법으로는 차단이 불가능하다. 따라서 본 논문에서는 기존의 음란사이트를 차단하기 위한 방법들 즉, 목록 기반 방법과 단어 기반 방법으로는 화상 채팅 사이트에서 이루어지고 있는 음란 행위를 차단할수 없으므로 이를 내용 기반으로 문제가 되는 채팅방만을 선택적으로 차단하기 위한 방법론을 제시함을 본 연구의 목적으로 한다. 최종적으로 본 연구는 내용 기반으로 화상 채팅방에서 문제가 되는 채팅방에 대한 영상 차단, 음향 신호 차단을 행하여 청소년들을 보호하는 데 기여하고자 한다. 본 연구의 유용성을 입증하기 위해 불건전한 음란 장면과 음향에 대해 실험을 수행하였으며 실험 수행 결과 음란의 장면이 담긴 영상과 음향 신호를 정확히 차단할수 있었으며 이를 통해 화상 채팅방의 건전한 사용 및 이용을 유도할수 있을 것으로 여겨진다.

• Safety and Health at Work
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• 제11권3호
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• pp.275-283
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• 2020

Background: In the absence of a vaccine or treatment, the most pragmatic strategies against an infectious disease pandemic are extensive early detection testing and social distancing. This study aimed to summarize public and workplace responses to Coronavirus Disease-19 (COVID-19) and show how the Korean system has operated during the COVID-19 pandemic. Method: Daily briefings from the Korean Center for Disease Control and the Central Disaster Management Headquarters were assembled from January 20 to May 15, 2020. Results: By May 15, 2020, 11,018 COVID-19 cases were identified, of which 15.7% occurred in workplaces such as health-care facilities, call centers, sports clubs, coin karaoke, and nightlife destinations. When the first confirmed case was diagnosed, the Korean Center for Disease Control and Central Disaster Management Headquarters responded quickly, emphasizing early detection with numerous tests and a social distancing policy. This slowed the spread of infection without intensive containment, shut down, or mitigation interventions. After entering the public health blue alert level, a business continuity plan was distributed. After entering the orange level, the Ministry of Employment and Labor developed workplace guidelines for COVID-19 consisting of social distancing, flexible working schedules, early identification of workers with suspected infections, and disinfection of workplaces. Owing to the intensive workplace social distancing policy, workplaces remained safe with only small sporadic group infections. Conclusion: The workplace social distancing policy with timely implementation of specific guidelines was a key to preventing a large outbreak of COVID-19 in Korean workplaces. However, sporadic incidents of COVID-19 are still ongoing, and risk assessment in vulnerable workplaces should be continued.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2002년도 Proceedings of the International Welding/Joining Conference-Korea
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• pp.675-680
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• 2002

Cracking and bulging in welded and internally lined pressure vessels that work in thermal-mechanical cycling service have been well known problems in the petrochemical, power and nuclear industries. However, published literature and industry surveys show that similar problems have been occurring during the last 50 years. A better understanding of the causes of cracking and bulging causes is needed to improve the reliability of these pressure vessels. This study attempts to add information required for increasing the knowledge and fundamental understanding required. Typical examples of this problem are the coke drums in the delayed coking units refinery process. This case was selected for experimental work, field study and results comparison. Delayed coking units are among the refinery units that have higher economical yields. To shut down these units represents a high negative economical impact in refinery operations. Also, the maintenance costs associated with repairs are commonly very high. Cracking and bulging occurrences in the coke drums, most often at the weld areas, characterize the history of the operation of delayed coking units. To design and operate more robust coke drums with fewer problems, an improved metallurgical understanding of the cracking and bulging mechanisms is required. A methodology that is based field experience revision and metallurgical analyses for the screening of the most important variables, and subsequent finite element analyses to verify hypotheses and to rank the variables according to their impact on the coke drum lives has been developed. This indicated approach provides useful information for increasing coke drum reliability. The results of this work not only order the most important variables according to their impact in the life of the vessels, but also permit estimation of the life spans of coke drums. In conclusion, the current work shows that coke drums may fail as a combination of thermal fatigue and other degradation mechanisms such as: corrosion at high and low temperatures, detrimental metallurgical transformations and plastic deformation. It was also found that FEA is a very valuable tool for understanding cracking and bulging mechanisms in these services and for ranking the design, fabrication, operation and maintenance variables that affect coke drum reliability.

• 한국융합학회논문지
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• 제8권11호
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• pp.393-401
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• 2017

최근 스마트워크를 도입했던 선도 기업들이 스마트워크를 축소하거나 폐지하는 사례가 나타나고 있다. 스마트워크는 직무만족에 긍정적으로 작용하며, 직무만족은 생산성의 향상을 가져올 것이라는 기존 연구들의 예측에 대한 의구심이 제기되고 있다. 따라서 본 논문에서는 스마트워크와 직무만족 및 생산성 간의 관계를 재검토하고자 한다. 이를 위해 한국과학기술정보센터의 NDSL 데이터베이스를 기반으로 스마트워크와 관련된 8건의 문헌을 선정하여 체계적으로 분석하였다. 선행 연구들에서는 스마트워크는 직무만족에, 직무만족은 생산성 향상에 긍정적인 영향을 미치고 있음을 실증하고 있었다. 하지만 기존 연구에서 스마트워크가 직무만족을 가져다준다는 실증이나 직무만족 개념에 대한 정의와 측정 등에서 문제의 가능성이 있음을 발견하였다. 이와 관련하여 본 연구는 스마트워크와 직무만족, 그리고 삶의 만족과 직무만족에 대해 심층적으로 논의하고, 향후 연구 방향을 제시하였다.

• 한국컴퓨터정보학회논문지
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• 제19권12호
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• pp.1-10
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• 2014

본 논문에서는 다중코어 프로세서 상에서 주기적 실시간 작업들의 데드라인을 만족하면서 전력 소모량을 최소화하도록 DVFS 기법과 전원 소등 기법을 모두 사용하는 스케줄링 방법을 제안하였다. 제안된 스케줄링 방법은 프로세싱 코어들이 단일 시점에 같은 속도로 동작하는 연관형 프로세서 모델에 적합하도록 설계되었고, 기존 연구에서 해결하지 못한 프로세싱 코어들의 부하불균등 현상을 병렬 수행을 작업들에 적용하여 해소함으로써 전력 소모량을 줄였다. 또한 작업들의 전체 계산량을 고려하여 일부 프로세싱 코어들만을 활성화하여 사용하고 나머지 코어들의 전원은 소등하여 전력 소모량을 줄였다. 전체 프로세싱 코어들 중에서 활성화될 프로세싱 코어들의 개수는 수학적 분석을 통하여 결정되었다. 성능 평가 실험에서 제안된 방법은 기존 방법보다 전력 소모량을 최대 77%까지 감소시킴을 보였다.

• Journal of Information Technology Applications and Management
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• 제26권6호
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• pp.103-117
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• 2019

Demand for high power motors is rapidly increasing as the 4th industry and convergence technology has recently emerged. In order to produce high-strength permanent magnets, the magnets used for magnetization have been increased from DC 300V in the 1970s to DC 2.5kV in the 2010s, Up to DC 10kV in the 2030s, It is expected that higher voltage will be used to magnetize. However, in the case of a magnetizer using an existing electric signal control device, it is necessary to use a control device with a high-voltage insulation function in case a high voltage used for magnetization is leaked to the control device. If a short circuit accident occurs, the controller must be shut down and serious problems such as excessive repair costs arise. In this study, a control system adopting optical communication method instead of electric signal control method is proposed to prevent leakage currents in high-voltage magnetizer. We design a transmitter(Tx) and a receiver(Rx) device for the optical communication control device and implemented a prototype connecting the optical cable. In order to demonstrate the utility of high-voltage magnetizer using the optical communication control device, we analyzed the initial cost and the yearly cost for the years to analyze the net present value. As a result, In the case of the low-voltage magnetizer, the electric signal control method cost less, As the operating voltage of the magnetizer becomes higher. It is confirmed that it takes less cost when the optical communication control device is used.

• Journal of Radiation Protection and Research
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• 제45권2호
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• pp.81-87
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• 2020

Background: Kori unit #1 is permanently shut down after a 40-year lifetime. The Nuclear Safety and Security Commission recommends establishing initial decommissioning plans for all nuclear and radwaste treatment facilities. Therefore, the Korea Atomic Energy Research Institute (KAERI) must establish an initial and final decommissioning plan for radwaste-treatment facilities. Radiation safety assessment, which constitutes one chapter of the decommissioning plan, is important for establishing a decommissioning schedule, a strategy, and cost. It is also a critical issue for the government and public to understand. Materials and Methods: This study provides a method for assessing external radiation dose to workers during decommissioning. An external dose is calculated following each exposure scenario, decommissioning strategy, and working schedule. In this study, exposure dose is evaluated using the deterministic method. Physical characterization of the facility is obtained by both direct measurement and analysis of the drawings, and radiological characterization is analyzed using the annual report of KAERI, which measures the ambient dose every month. Results and Discussion: External doses are calculated at each stage of a decommissioning strategy and found to increase with each successive stage. The maximum external dose was evaluated to be 397.06 man-mSv when working in liquid-waste storage. To satisfy the regulations, working period and manpower must be managed. In this study, average and cumulative exposure doses were calculated for three cases, and the average exposure dose was found to be about 17 mSv/yr in all the cases. Conclusion: For the three cases presented, the average exposure dose is well below the annual maximum effective dose restriction imposed by the international and domestic regulations. Working period and manpower greatly affect the cost and entire decommissioning plan; hence, the chosen option must take account of these factors with due consideration of worker safety.

• 한국안전학회지
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• 제24권2호
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• pp.17-22
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• 2009

Thermal stress and elastic creeping stress analysis was conducted by finite element method to simulate start-up process of a boiler header of 500MW standard fossil power plant. Start-up temperature and operating pressure history were simplified from the real field data and they were used for the thermal stress analysis. Two kinds of thermal stress analysis were considered. In the first case only temperature increase was considered and in the second case both of temperature and operating pressure histories were considered. In the first analysis peak stress was occurred during the temperature increase from the room temperature. Hence cracking or fracture may occur at the temperature far below the operating maximum temperature. In the results of the second analysis von Mises stress appeared to be higher after the second temperature increase. This is due to internal pressure increase not due to the thermal stress. When the stress components of radial(r), hoop($\theta$) and longitudinal(z) stress were investigated, compression hoop stress was occurred at inner surface of the stub tube when the temperature increased from room temperature to elevated temperature. Then it was changed to tension hoop stress and increased because of the operating pressure. It was expected that frequent start-up and shut-down operations could cause thermal fatigue damage and cracking at the stub tube hole in the header. Elastic-creeping analysis was also carried out to investigate the stress relaxation due to creep and stabilized stress after considerable elapsed time. The results could be used for assessing the creep damage and the residual life of the boiler header during the long-tenn service.