• 한국압력기기공학회 논문집
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• 제10권1호
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• pp.31-36
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• 2014

For decreasing an unexpected shutdown of Nuclear Power Plants, Korea Hydro & Nuclear Power co.(KHNP) has developed Single Point Vulnerability(SPV) of NPPs since 2008. SPV is the equipment that cause reactor shutdown & turbine trip or more than 50% power rundown due to its malfunction. New type Nuclear Power Plants need to develop the SPV list, so performed the SPV selection for about 1 year. To develop this, Failure Mode Effect Analysis(FMEA) methods are used. As results of FMEA analysis, about 700 equipment are selected as SPV. Thereafter those are going to be applied to new type Nuclear Power Plants to enhance equipment reliability.

• 전기학회논문지
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• 제61권4호
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• pp.509-512
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• 2012

For decreasing an unexpected shutdown of Nuclear Power Plants, Korea Hydro & Nuclear Power co.(KHNP) has developed Single Point Vulnerability(SPV) of NPPs since 2008. SPV is the equipment that cause reactor shutdown & turbine trip or more than 50% power rundown due to its malfunction. Newly built Nuclear Power Plants need to develop the SPV list, so performed the job which analyse equipment failure effect for SPV selection for 1 year. To develop this, Failure Mode Effect Analysis(FMEA) and Fault Tree Analysis(FTA) methods are used. As results of this analysis, about 900 equipment are selected as SPV. Thereafter those are going to be applied to Nuclear Power Plants to enhance equipment reliability.

• 식물분류학회지
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• 제36권2호
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• pp.91-108
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• 2006

한국산 Geranium(쥐손이풀속) 16분류군과 3개의 군외군을 대상으로 진화와 유연관계를 평가하기 위하여 nuclear ribosomal DNA 중 internal transcribed spacer (ITS) 구간에 대한 계통 분류학적 분석을 수행하였다. 계통 분류학적 연구들은 bootstrapping, jackknifing을 포함한 parsimony 방법과 neighbor-joining 방법을 사용하였다. 그 결과 한국산 쥐손이풀속은 단계통군을 형성하였다. Parsimony tree에서 한라이질풀은 가장 기부에 위치하였으며 Erianthum group은 높은 지지도에 의해 하나의 분계조를 형성하였다(100% bootstrap과 jackknife values). Krameri group인 산쥐손이는 Palustre group인 섬쥐손이와 가까이 위치하였으나 그 지지도는 매우 낮았고(37% bootstrap과 44% jackknife values) strict tree에서는 clade가 붕괴되었다. Wilfordii group에 분류되었던 큰세잎쥐손이는 Koreanum group과 가까이 위치하였고, Sibiricum group인 쥐손이풀은 Krameri group인 삼쥐손이와 가까이 위치하였으며 또한 이 두 종은 역시 Krameri group인 선이질풀과 자매군을 이루었다. Wilfordii group인 좀쥐손이와 세잎쥐손이는 Sibiricum group인 삼이질풀, 이질풀과 가까이 위치하였다. 이와 같은 결과는 많은 학자들에 의해 논란이 된 분류군들의 문제를 해결하는데 유용한 접근방법이라 생각되며, 전체 쥐손이풀속 수준에서의 계통분석에 유용한 도구로 이용될 수 있을 것으로 판단된다.

• 한국수산과학회지
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• 제46권1호
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• pp.53-58
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• 2013

The active antifouling compounds coumarin and its derivatives were isolated from the cinnamon tree Cinnamomum loureiroi. The antifouling activities were determined using representative soft fouling organisms: the seaweed Ulvapertusa and diatom Navicula annexa. The chemical constituents with antifouling activities were identified as coumarin, hydroxylcoumarin, coumaric acid, and cinnamaldehyde by interpreting nuclear magnetic resonance, and high-resolution mass spectroscopy data. These compounds were isolated from 1.09 g of crude Cinnamomum sp. methanol extract, yielding approximately 18.4, 6.3, 9.8, and 14.7 mg of coumarin, hydroxylcoumarin, coumaric acid, and cinnamaldehyde, respectively. The compounds inhibited U. pertusa zoospores with $EC_{50}$ values of $0.13-0.25{\mu}g/mL$, and the diatom N. annexa with $EC_{50}$ of $0.21-0.81{\mu}g/mL$.

• 식물분류학회지
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• 제44권1호
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• pp.39-50
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• 2014

엽록체 matK 유전자와 핵 ITS 염기서열을 이용하여 나도풍란속 및 풍란속의 계통학적 위치를 정립하였다. 또한, 이들 마커를 이용하여 종 및 원산지 추적에 활용가능성을 평가하였다. 풍란속과 나도풍란속은 두 마커 모두에서 뚜렷한 단계통군을 형성하였다. 풍란속의 자매군은 Vanda임이 두 마커 모두에서 입증되었으나,본 연구 결과는 풍란속을 Vanda에 포함시키는 처리에는 동의하지 않았다. 나도풍란속은 (Dimorphorchis (Pteroceras (Saccolabiun+Phalaeonopsis))) 계통군과 자매군을 형성하였고, 이중 Dimorphorchis와 자매속일 가능성이 가장 높았다. 형태적 유사성으로 나도풍란속이 Aerides와 자매속이라는 주장의 가능성은 희박하였다. 두 마커를 분석한 결과 풍란속의 경우 종 및 종 내의 산지별 구별이 가능한 것으로 평가되었다. 따라서 풍란의 재배 개체들의 기원을 규명하는데도 유용한 것으로 평가되었다. 그러나, 공공 염기서열 DB에 있는 서열들은 의유전자로 추정되는 서열들을 다수 포함하고 있었다. 또한, 재배 난과식물에는 속간 및 종간 잡종이 많으며 잡종에 의한 수평적 유전자 이동문제 등이 결부되어 있으므로, 계통학적으로 염기서열 자료를 이용하는데 주의하여야 한다. 계통분석을 위하여는 한 종 내의 여러 개체로부터 염기서열을 확보하는 것이 이러한 위험성을 줄이는 방법 중에 하나이다.

• Nuclear Engineering and Technology
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• 제44권7호
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• pp.755-766
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• 2012

A Binary Decision Diagram (BDD) is a graph-based data structure that calculates an exact top event probability (TEP). It has been a very difficult task to develop an efficient BDD algorithm that can solve a large problem since its memory consumption is very high. Recently, in order to solve a large reliability problem within limited computational resources, Jung presented an efficient method to maintain a small BDD size by a BDD truncation during a BDD calculation. In this paper, it is first identified that Jung's BDD truncation algorithm can be improved for a more practical use. Then, a more efficient truncation algorithm is proposed in this paper, which can generate truncated BDD with smaller size and approximate TEP with smaller truncation error. Empirical results showed this new algorithm uses slightly less running time and slightly more storage usage than Jung's algorithm. It was also found, that designing a truncation algorithm with ideal features for every possible fault tree is very difficult, if not impossible. The so-called ideal features of this paper would be that with the decrease of truncation limits, the size of truncated BDD converges to the size of exact BDD, but should never be larger than exact BDD.

• Genomics & Informatics
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• 제10권1호
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• pp.9-15
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• 2012

Horizontal gene transfer (HGT) is the movement of genetic material between kingdoms and is considered to play a positive role in adaptation. $Cryptosporidium$ $parvum$ is a parasitic protozoan that causes an infectious disease. Its genome sequencing reported 14 bacteria-like proteins in the nuclear genome. Among them, cgd2_1810, which has been annotated as CysQ, a sulfite synthesis pathway protein, is listed as one of the candidates of genes horizontally transferred from bacterial origin. In this report, we examined this issue using phylogenetic analysis. Our BLAST search showed that $C.$ $parvum$ CysQ protein had the highest similarity with that of proteobacteria. Analysis with NCBI's Conserved Domain Tree showed phylogenetic incongruence, in that $C.$ $parvum$ CysQ protein was located within a branch of proteobacteria in the cd01638 domain, a bacterial member of the inositol monophosphatase family. According to Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway, the sulfate assimilation pathway, where CysQ plays an important role, is well conserved in most eukaryotes as well as prokaryotes. However, the Apicomplexa, including $C.$ $parvum$, largely lack orthologous genes of the pathway, suggesting its loss in those protozoan lineages. Therefore, we conclude that $C.$ $parvum$ regained cysQ from proteobacteria by HGT, although its functional role is elusive.

• Nuclear Engineering and Technology
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• 제51권6호
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• pp.1540-1553
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• 2019

A nuclear power plant (NPP) is a highly complex system-of-systems as manifested through its internal systems interdependence. The negative impact of such interdependence was demonstrated through the 2011 Fukushima Daiichi nuclear disaster. As such, there is a critical need for new strategies to overcome the limitations of current risk assessment techniques (e.g. the use of static event and fault tree schemes), particularly through simulation of the nonlinear dynamic feedback mechanisms between the different NPP systems/components. As the first and key step towards developing an integrated NPP dynamic probabilistic risk assessment platform that can account for such feedback mechanisms, the current study adopts a system dynamics simulation approach to model the thermal dynamic processes in: the reactor core; the secondary coolant system; and the pressurized water reactor. The reactor core and secondary coolant system parameters used to develop system dynamics models are based on those of the Palo Verde Nuclear Generating Station. These three system dynamics models are subsequently validated, using results from published work, under different system perturbations including the change in reactivity, the steam valve coefficient, the primary coolant flow, and others. Moving forward, the developed system dynamics models can be integrated with other interacting processes within a NPP to form the basis of a dynamic system-level (systemic) risk assessment tool.

• ALGAE
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• 제28권4호
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• pp.307-330
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• 2013

The genus Cryptomonas is easily recognized by having two flagella, green brownish color, and a swaying behavior. They have relatively simple morphology, and limited diagnostic characters, which present a major difficulty in differentiating between species of the genus. To understand species delineation and phylogenetic relationships among Cryptomonas species, the nuclear-encoded internal transcribed spacer 2 (ITS2), partial large subunit (LSU) and small subunit ribosomal DNA (rDNA), and chloroplast-encoded psbA and LSU rDNA sequences were determined and used for phylogenetic analyses, using Bayesian and maximum likelihood methods. In addition, nuclear-encoded ITS2 sequences were predicted to secondary structures, and were used to determine nine species and four unidentified species from 47 strains. Sequences of helix I, II, and IIIb in ITS2 secondary structure were very useful for the identification of Cryptomonas species. However, the helix IV was the most variable region across species in alignment. The phylogenetic tree showed that fourteen species were monophyletic. However, some strains of C. obovata had chloroplasts with pyrenoid while others were without pyrenoid, which used as a key character in few species. Therefore, classification systems depending solely on morphological characters are inadequate, and require the use of molecular data.

• Nuclear Engineering and Technology
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• 제49권2호
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• pp.411-425
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• 2017

Using a probabilistic safety assessment, a risk evaluation framework for an aircraft crash into an interim spent fuel storage facility is presented. Damage evaluation of a detailed generic cask model in a simplified building structure under an aircraft impact is discussed through a numerical structural analysis and an analytical fragility assessment. Sequences of the impact scenario are shown in a developed event tree, with uncertainties considered in the impact analysis and failure probabilities calculated. To evaluate the influence of parameters relevant to design safety, risks are estimated for three specification levels of cask and storage facility structures. The proposed assessment procedure includes the determination of the loading parameters, reference impact scenario, structural response analyses of facility walls, cask containment, and fuel assemblies, and a radiological consequence analysis with dose-risk estimation. The risk results for the proposed scenario in this study are expected to be small relative to those of design basis accidents for best-estimated conservative values. The importance of this framework is seen in its flexibility to evaluate the capability of the facility to withstand an aircraft impact and in its ability to anticipate potential realistic risks; the framework also provides insight into epistemic uncertainty in the available data and into the sensitivity of the design parameters for future research.