• Nuclear Engineering and Technology
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• v.49 no.4
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• pp.710-720
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• 2017

In Korea, many nuclear power plants operate at a single site based on geographical characteristics, but the population density near the sites is higher than that in other countries. Thus, multiunit accidents are a more important consideration than in other countries and should be addressed appropriately. Currently, there are many issues related to a multiunit probabilistic safety assessment (PSA). One of them is the quantification of a multiunit PSA model. A traditional PSA uses a Boolean manipulation of the fault tree in terms of the minimal cut set. However, such methods have some limitations when rare event approximations cannot be used effectively or a very small truncation limit should be applied to identify accident sequence combinations for a multiunit site. In particular, it is well known that seismic risk in terms of core damage frequency can be overestimated because there are many events that have a high failure probability. In this study, we propose a quantification method based on a Monte Carlo approach for a multiunit PSA model. This method can consider all possible accident sequence combinations in a multiunit site and calculate a more exact value for events that have a high failure probability. An example model for six identical units at a site was also developed and quantified to confirm the applicability of the proposed method.

• Molecules and Cells
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• v.39 no.6
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• pp.495-500
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• 2016

We have solved the crystal structure of a predicted fructose-specific enzyme $IIB^{fruc}$ from Escherichia coli ($EcEIIB^{fruc}$) involved in the phosphoenolpyruvate-carbohydrate phosphotransferase system transferring carbohydrates across the cytoplasmic membrane. $EcEIIB^{fruc}$ belongs to a sequence family with more than 5,000 sequence homologues with 25-99% amino-acid sequence identity. It reveals a conventional Rossmann-like ${\alpha}-{\beta}-{\alpha}$ sandwich fold with a unique ${\beta}$-sheet topology. Its C-terminus is longer than its closest relatives and forms an additional ${\beta}$-strand whereas the shorter C-terminus is random coil in the relatives. Interestingly, its core structure is similar to that of enzyme $IIB^{cellobiose}$ from E. coli ($EcIIB^{cel}$) transferring a phosphate moiety. In the active site of the closest $EcEIIB^{fruc}$ homologues, a unique motif CXXGXAHT comprising a P-loop like architecture including a histidine residue is found. The conserved cysteine on this loop may be deprotonated to act as a nucleophile similar to that of $EcIIB^{cel}$. The conserved histidine residue is presumed to bind the negatively charged phosphate. Therefore, we propose that the catalytic mechanism of $EcEIIB^{fruc}$ is similar to that of $EcIIB^{cel}$ transferring phosphoryl moiety to a specific carbohydrate.

• Molecules and Cells
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• v.37 no.5
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• pp.372-382
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• 2014

In this study, the chloroplast (cp) genome sequences from three early diverged leptosporangiate ferns were completed and analyzed in order to understand the evolution of the genome of the fern lineages. The complete cp genome sequence of Osmunda cinnamomea (Osmundales) was 142,812 base pairs (bp). The cp genome structure was similar to that of eusporangiate ferns. The gene/intron losses that frequently occurred in the cp genome of leptosporangiate ferns were not found in the cp genome of O. cinnamomea. In addition, putative RNA editing sites in the cp genome were rare in O. cinnamomea, even though the sites were frequently predicted to be present in leptosporangiate ferns. The complete cp genome sequence of Diplopterygium glaucum (Gleicheniales) was 151,007 bp and has a 9.7 kb inversion between the trnL-CAA and trnV-GCA genes when compared to O. cinnamomea. Several repeated sequences were detected around the inversion break points. The complete cp genome sequence of Lygodium japonicum (Schizaeales) was 157,142 bp and a deletion of the rpoC1 intron was detected. This intron loss was shared by all of the studied species of the genus Lygodium. The GC contents and the effective numbers of codons (ENCs) in ferns varied significantly when compared to seed plants. The ENC values of the early diverged leptosporangiate ferns showed intermediate levels between eusporangiate and core leptosporangiate ferns. However, our phylogenetic tree based on all of the cp gene sequences clearly indicated that the cp genome similarity between O. cinnamomea (Osmundales) and eusporangiate ferns are symplesiomorphies, rather than synapomorphies. Therefore, our data is in agreement with the view that Osmundales is a distinct early diverged lineage in the leptosporangiate ferns.

• Korean Journal of Plant Resources
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• v.33 no.5
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• pp.536-549
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• 2020

Soybean (Glycine max (L.) Merrill) is one of the most important crops of the world. With the completion of the soybean genome sequence, the Korean soybean core collection consisted of 430 accessions with genetic and phenotypic diversity was constructed in recent year. The availability of genome sequences and core collection will result in the crop improvement by molecular breeding using the various accessions and genome editing approaches. Efficient tissue culture techniques, such as haploid production, protoplast culture and plant regeneration from various organs are essential for the successful molecular biological approach and crop improvement. However, soybean is still considered to be recalcitrant in tissue culture because of the low frequency of regeneration and limitation of available responsive cultivars. In this study, we discuss the recent studies of tissue culture technology and methodology for efficient tissue culture to genetic improvement and application of molecular biotechnology in soybean.

• Journal of the Korean Chemical Society
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• v.43 no.4
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• pp.393-400
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• 1999

Dendritic carbosilanes based on hyperbranched polycarbosilanes as core molecule have been prepared The core molecules were obtained by the use of hydrosilation of $HSiMe_{3-n}$$(CH_2CH=CH_2)_n$(n=2; $AB_2$,3;$AB_3$type). The hyperbranched core $AB_2\;and\; AB_3$ type polymers were generated to higher molecular dendritic carbosilanes Gn+1 by the use of hydrosilation and alkenylation sequence. The Gn+2P generations were not obtained as unified molecules by the use of hydrosilation with $HSiMeCl_2$. Gn and Gn+1 type polymers were produced to polysilol by the reaction of 9-BBN and alkali medium oxidation of hydroborated compounds. The degree for reaction has been controlled by the NMR spectroscopy.

• The Journal of the Convergence on Culture Technology
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• v.7 no.3
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• pp.591-598
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• 2021

It's possible to get the word-vector by the statistical SVD or deep-learning CBOW and LSTM methods and theses ones learn the contexts of forward/backward words or the sequence of following words. It's used to analyze the poems by Ki Hyung-do with similar words recommended by the word-vector showing the core images of the poetry. It seems at first sight that the words don't go well with the images but they express the similar style described by the reference words once you look close the contexts of the specific poems. The word-vector can analogize the words having the same relations with the ones between the representative words for the core images of the poems. Therefore you can analyze the poems in depth and in variety with the similarity and analogy operations by the word-vector estimated with the statistical SVD or deep-learning CBOW and LSTM methods.

• The Journal of Engineering Geology
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• v.24 no.1
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• pp.9-21
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• 2014

We examined high-resolution seismic data, side scan sonar data, surface sediments, and vibrocore samples from a sand ridge off the western part of Dukjuk-Do in Gyeonggi Bay, with the aim of interpretation of seismic stratigraphy and sedimentary environment. Based on the seismic data, the deposited sands are divided into three sedimentary units. 14C age data indicate that the top sequence (sequence I) formed at 5000-6000 yr BP, when a transgression resulted in strong shifting tides. Analyses of the vibrocore samples indicate that sequence II is a paleo-mudflat layer of intertidal sediments dominated by mud. Sequence III consists of terrestrial sediments that are presumed to have been deposited at the end of the Pleistocene, unconformably overlying the acoustic bedrock and Mesozoic granite. The side scan sonar data indicate that sand waves were formed on the seabed on top of the sand ridge. Generally, this is the direction of $N20^{\circ}E$, which coincides with the direction of tidal flow. Sand ripples occur away from the top of the sand ridge and are distributed homogeneously across a sandy slope. Vibrocore analyses indicate that the surface sediments and core sediments (samples VC-1, -2, and -3) are homogeneous, without any internal structures, and are characterized by a mixture of medium and fine sand (1-$2{\phi}$), respectively.

• Journal of Pharmaceutical Investigation
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• v.37 no.3
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• pp.197-203
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• 2007

A bioequivalence study of $Dilast^{TM}$ Capsule (Chong Kun Dang Pharma. Co., Ltd.) to $Ketas^{(R)}$ Capsule (Han Dok Pharma. Co., Ltd.) was conducted according to the guidelines of Korea Food and Drug Administration (KFDA). Twenty eight healthy male Korean volunteers received each medicine at the ibudilast dose of 20 mg in a $2{\times}2$ crossover study. There was one week wash-out period between the doses. Plasma concentrations of ibudilast were monitored by a liquid chromatography-tandem mass spectrometry (LC-MS/MS) for over a period of 36 hours after drug administration. $AUC_t$ (the area under the plasma concentration-time curve from time zero to 36 hr) was calculated by the linear trapezoidal rule method. $C_{max}$ (maximum plasma drug concentration) and $T_{max}$ (time to reach $C_{max}$) were compiled from the plasma concentration-time data. Analysis of variance was carried out using logarithmically transformed $AUC_t\;and\;C_{max}$. No significant sequence effect was found for all of the bioavailability parameters indicating that the crossover design was properly performed. The 90% confidence intervals of the $AUC_t$ ratio and the $C_{max}$ ratio for $Dilast^{TM}$ $Capsule/Ketas^{(R)}$ Capsule were $log0.93{\sim}log1.06$ and $log0.93{\sim}log1.11$, respectively. These values were within the acceptable bioequivalence intervals of $log0.80{\sim}log1.25$. Thus, our study demonstrated the bioequivalence of $Dilast^{TM}$ Capsule and $Ketas^{(R)}$ Capsule with respect to the rate and extent of absorption.

• Journal of applied mathematics & informatics
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• v.25 no.1_2
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• pp.455-470
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• 2007

In phylogenetic tree construction the neighbor-joining algorithm is the most well known method which constructs a trivalent tree from a pairwise distance data measured by DNA sequences. The core part of the algorithm is its cherry picking criterion based on the tree structure of each quartet. We give a generalized version of the criterion based on the exact box model of quartets, known as the tight span of a metric. We also show by experiment why neighbor-joining and the quartet consistency count method give similar performance.

• Nuclear Engineering and Technology
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• v.44 no.3
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• pp.311-322
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• 2012

Since the crisis at the Fukushima plants, severe accident progression during a station blackout accident in nuclear power plants is recognized as a very important area for accident management and emergency planning. The purpose of this study is to investigate the comparative characteristics of anticipated severe accident progression among the three typical types of nuclear reactors. A station blackout scenario, where all off-site power is lost and the diesel generators fail, is simulated as an initiating event of a severe accident sequence. In this study a comparative analysis was performed for typical pressurized water reactor (PWR), boiling water reactor (BWR), and pressurized heavy water reactor (PHWR). The study includes the summarization of design differences that would impact severe accident progressions, thermal hydraulic/severe accident phenomenological analysis during a station blackout initiated-severe accident; and an investigation of the core damage process, both within the reactor vessel before it fails and in the containment afterwards, and the resultant impact on the containment.