• Proceedings of the Korean Nuclear Society Conference
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• 1996.05a
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• pp.571-576
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• 1996

Currently most nuclear power plants(NPPs) are adopted the mid-loop operation to minimize the overhaul period and save the operating cost. For mid-loop operation it is essential to install nozzle dam between RCS pipe and steam generator(SG). Because SG remains more highly contaminated with radioactive material than any other parts of the NPPs, the repairmen are very reluctant to carry out installing nozzle dam inside the SG. Until now, unfortunately, it appears that no practically applicable device was developed to provide the longstanding demand. Also the accidents have been reported by licenser event report during this operation mode due to loss of residual heat removal(RHR). The purpose of this paper is to conduct remotely blocking and disintegration of nozzle of a SG which has the highest radiation exposure during the maintenance in NPPs. The remote nozzle blocking device of a SG includes three bladders, hubs, air controller provisions to supply and contact air pressure into the bladders. This remote nozzle block device will give the larger operation margin to prevent the loss of RHR and minimize the radiation exposure dose to the repairman and shorten the overhaul periods.

• Nuclear Engineering and Technology
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• v.42 no.4
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• pp.460-467
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• 2010

In this study, the parameters of the feedwater control system (FWCS) of the OPR1000 type nuclear power plant (NPP) are optimized by response surface methodology (RSM) in order to acquire better level control performance from the FWCS. The objective of the optimization is to minimize the steam generator (SG) water level deviation from the reference level during transients. The objective functions for this optimization are relationships between the SG level deviation and the parameters of the FWCS. However, in this case of FWCS parameter optimization, the objective functions are not available in the form of analytic equations and the responses (the SG level at plant transients) to inputs (FWCS parameters) can be evaluated by computer simulations only. Classical optimization methods cannot be used because the objective function value cannot be calculated directely. Therefore, the simulation optimization methodology is used and the RSM is adopted as the simulation optimization algorithm. Objective functions are evaluated with several typical transients in NPPs using a system simulation computer code that has been utilized for the system performance analysis of actual NPPs. The results show that the optimized parameters have better SG level control performance. The degree of the SG level deviation from the reference level during transients is minimized and consequently the control performance of the FWCS is remarkably improved.

• Journal of Microbiology and Biotechnology
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• v.33 no.5
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• pp.582-590
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• 2023

Stress granules (SGs) are cytoplasmic aggregates of RNA-protein complexes that form in response to various cellular stresses and are known to restrict viral access to host translational machinery. However, the underlying molecular mechanisms of SGs during viral infections require further exploration. In this study, we evaluated the effect of SG formation on cellular responses to coxsackievirus B3 (CVB3) infection. Sodium arsenite (AS)-mediated SG formation suppressed cell death induced by tumor necrosis factor-alpha (TNF-a)/cycloheximide (CHX) treatment in HeLa cells, during which G3BP1, an essential SG component, contributed to the modulation of apoptosis pathways. SG formation in response to AS treatment blocked CVB3-mediated cell death, possibly via the reduction of mitochondrial reactive oxygen species. Furthermore, we examined whether AS treatment would affect small extracellular vesicle (sEV) formation and secretion during CVB3 infection and modulate human monocytic cell (THP-1) response. CVB3-enriched sEVs isolated from HeLa cells were able to infect and replicate THP-1 cells without causing cytotoxicity. Interestingly, sEVs from AS-treated HeLa cells inhibited CVB3 replication in THP-1 cells. These findings suggest that SG formation during CVB3 infection modulates cellular response by inhibiting the release of CVB3-enriched sEVs.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.19 no.2
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• pp.61-68
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• 2023

The phenomenon of fretting wear due to the flow-induced vibration in steam generator (SG) tube is a significant degradation mechanism in nuclear power plants. Fretting wear in SG tube is primarily attributed to the friction and impact forces between the SG tube and the tube support structures, experienced during nuclear power plants operation. While the Archard model has generally been used for the prediction of fretting wear in SG tube, it is limited by its linear nature. In this study, we introduced an "Impact Shear Work-rate" (ISW) model, which takes into account the combined effects of impact and sliding. The ISW model was evaluated using existing experimental data on fretting wear in SG tube and was compared against the Archard model. The prediction results using the ISW model were more accurate than those using the Archard model, particularly for impact forces.

• Electronics and Telecommunications Trends
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• v.35 no.6
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• pp.119-128
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• 2020

ISO/TC 268, IEC Systems Committee on Smart Cities, ISO/IEC JTC 1/WG 11, and ITU-T SG 20 have been developing smart city-related standards since 2013. ISO/TC 268 and ITU-T SG 20 have provided various and lots of smart city standards relatively. In this paper, the status of the standardization activities of ITU-T SG 20, the IEC Systems Committee on Smart Cities, ISO/TC 268, and ISO/IEC JTC 1/WG 11 is reviewed.

• Journal of the korean Society of Automotive Engineers
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• v.13 no.6
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• pp.16-21
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• 1991

자동차용 가솔린 엔진유의 품질은 엔진성능의 향상과 함께 점진적으로 발전되면서 서비스 수준에 의한 분류로 SA급에서부터 SF급까지 발전되어 왔다. 그러나 지난 1980년에 SF급 오일이 설정된 이후 8년이 지나서 새로운 가솔린 엔진 오일의 규격인 SG급이 1988년에 설정되었다. 본 고에서는 왜 SG급이 필요한가, 또 SF에 비해 어떤면이 얼마나 가혹하게 되었는가에 관하여 자세히 보고자 한다.

• Electronics and Telecommunications Trends
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• v.8 no.4
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• pp.68-78
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• 1993

1993 년 3 월 CCITT 가 TSS(Telecommunication Standardization Sector) 로 재구성됨에 따라 UPT(Universal Personal Telecommunication) 의 연구 및 표준화가 더욱 가속화될 예정이다. 이러한 추세에 맞추어 국내 및 소내에서도 UPT 에 대한 관심도가 날로 높아가고 있다. 본 고에서는 재구성된 UPT 관련 TSS 조직, TSS SG 11 및 PMG2 UPT 그룹, UPT 연구내용, UPT 발전방향 등을 중심으로 설명하고자 한다.

• Information and Communications Magazine
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• v.31 no.5
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• pp.34-38
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• 2014

정보보호 분야 국제표준화는 정보통신 관점에서 ITU-T SG17, 원천기술 관점에서 ISO/IEC JTC1/SC27, 인터넷 서비스 보안 관점에서 IETF Security Area에서 국제표준을 개발하고 있다. 또한, 아시아 지역 협력을 위해 ASTAP, RAISE Forum, CJK Security WG 등의 협의체를 구성하여 국제표준화기구에 대한 아시아 공동 대응체계를 구축해서 활동하고 있다. 본고에서는 2014년 1월, ITU-T SG17 국제회의 주요 결과와 향후 추진전망에 대해 알아본다.

• Review of KIISC
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• v.27 no.5
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• pp.33-37
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• 2017

국제전기통신연합(ITU)은 UN 산하에 신설된 국제기구로써, 산하에 전기통신표준화부문(ITU-T), 전기통신개발부문(ITU-D), 그리고 전파통신 부문(ITU-R) 등 3개의 부문으로 구성되어 있다[1],[2]. ITU-T SG17 (Study Group 17) 은 보안을 선도하고 있는 그룹으로 산하에 총 14개의 연구과제(Question)를 구성하여 국제표준을 개발 및 연구하고 있다. 본 논문에서는 ITU-T SG17 내에 저자가 라포처로 활동하고 있는 연구과제 2 (Q2, 보안구조 및 프레임워크) 국제표준화 동향 및 향후 추진방향에 대해 살펴보고자 한다.

• Review of KIISC
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• v.29 no.4
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• pp.25-28
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• 2019

본 논문에서는 국제전기통신연합(ITU)의 정보통신기술 표준을 담당하고 있는 ITU-T에서 보안 분야 표준을 제정하고 있는 SG17에서의 양자암호 표준화 동향을 소개하고자 한다. 양자암호통신은 더 이상 쪼갤 수 없는 물리량의 최소 단위인 양자(Quantum)의 특성을 이용해 도청 불가능한 암호키(Key)를 생성, 송신자와 수신자 양쪽에 나눠주는 기술로 이를 실제 다양한 보안 서비스에 적용하기 위해 필요한 구성 요소와 그 요소들 간의 상호호환성을 보장하기 위한 표준화 활동이 ITU-T SG17에서 진행되고 있어 그 내용을 간략히 살펴보았다.