• Nuclear Engineering and Technology
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• v.51 no.4
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• pp.1017-1023
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• 2019

The increase of the alternate current frequency results in increased rotational speed of the electrical motors and connected pumps. The consequence for the reactor coolant pumps is increased flow in primary coolant system. Increase of the current frequency can be initiated by the subsynchronous resonance phenomenon (SSR). This paper analyses the implications of the SSR and consequential increase of the frequency on the nuclear power plant safety. The Simulink $MATLAB^{(R)}$ model of the steam turbine and governor system and RELAP5 computer code of the pressurized water reactor are used in the analysis. The SSR results in fast increase of reactor coolant pumps speed and flow in the primary coolant system. The turbine trip value is reached in short time following SSR. The increase of flow of reactor coolant pumps results in increase of heat removal from reactor core. This results in positive reactivity insertion with reactor power increase of 0.5% before reactor trip is initiated by the turbine trip. The main parameters of the plant did not exceed the values of reactor trip set points. The pressure drop over reactor core is small discarding the possibility of core barrel lift.

• Journal of Ecology and Environment
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• v.37 no.1
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• pp.21-29
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• 2014

Robinia pseudoacacia has become invasively naturalized in Japan. We investigated the role of sexual reproduction in the development of R. pseudoacacia riparian forests along the Chikumagawa River in Japan, by using five chloroplast (cpSSR) and seven nuclear (nSSR) markers. We identified eight chloroplast haplotypes and 147 nuclear genotypes from 619 R. pseudoacacia trees sampled in three plots (Plots A, B, and C) and along two line transects (Lines D and E). CpSSR analyses showed that multiple maternal lines were distributed along the river, and that some haplotypes from different populations overlapped. In addition, while Plots A and B were separated by a short distance, only these two plots exhibited genetic differentiation in the haplotypes. In the nSSR analysis, all pairwise $F_{ST}$ values among the three plots were significantly different from zero. Kinship analysis based on nSSR markers revealed that kinship connected many individuals to another individual from the same plot. These results indicate that seed dispersal near to mother trees contributes to the fine-scale genetic structure of R. pseudoacacia riparian forests. Our results indicate that sexual reproduction, in addition to asexual reproduction, is a major contributor to the fine-scale formation of R. pseudoacacia forests.

• Journal of Korean Society of Forest Science
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• v.104 no.4
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• pp.578-587
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• 2015

Nuclear SSR (nSSR) and chloroplast SSR (cpSSR) markers were analyzed to assess the parameters of mating system in seed orchard, such as outcrossing rates, the number of potential pollen contributors, paternal contribution rates, degree of pollen contamination, and biparental inbreeding ($t_m-t_s$). In 2006, 2007, seeds were collected from the seed orchard of Pinus densiflora, established in 1977 at Anmyeon island. Estimates of outcrossing rates ranged from 94.9 to 100% (mean 98.9%) in 2006 and from 91.2 to 100% (mean 97.7%) in 2007 on the basis of the analysis of cpSSR haplotypes and from 90.3 to 100% (mean 95.9%) in 2006 and from 81.6 to 100% (mean 95.3%) in 2007 on the basis of the analysis of nSSR genotypes. By cross checking of both DNA markers, mean cumulative outcrossing rates of 100% and 98.9% were estimated in each year. Mean contamination rates were estimated as 48.9% and 42.4%, respectively. On the basis of cpSSR haplotype observed in each seed, paternal contribution rates (the number of pollen contributors) were estimated as 0.458 (mean 16.2) in 2006 and 0.512 (mean 14.8) in 2007. In conclusion, considering pretty high level of outcrossing rates observed in a seed orchard, there might be little to be influenced by inbreeding depression for genetic potential of the seeds induced by selfing. Estimates of the mating system parameters obtained from the two reproductive years were not statistically different, which revealed stable genetic quality of seeds produced in different years. Observed results from this study may provide useful information for the management and establishment of the seed orchard of the progressive generation.

• Nuclear Engineering and Technology
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• v.55 no.4
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• pp.1476-1484
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• 2023

Laboratory experiments and point monitoring of reservoir sediments have proven that stable sulfate reduction (SSR) can lower the concentrations of toxic metals and sulfate in acidic groundwater for a long time. Here, we hypothesize that SSR occurred during in situ leaching after uranium mining, which can impact the fate of acid groundwater in an entire region. To test this, we applied a sulfur isotope fractionation method to analyze the mechanism for natural attenuation of contaminated groundwater produced by acid in situ leaching of uranium (Xinjiang, China). The results showed that δ³⁴S increased over time after the cessation of uranium mining, and natural attenuation caused considerable, area-scale immobilization of sulfur corresponding to retention levels of 5.3%-48.3% while simultaneously decreasing the concentration of uranium. Isotopic evidence for SSR in the area, together with evidence for changes of pollutant concentrations, suggest that area-scale SSR is most likely also important at other acid mining sites for uranium, where retention of acid groundwater may be strengthened through natural attenuation. To recapitulate, the sulfur isotope fractionation method constitutes a relatively accurate tool for quantification of spatiotemporal trends for groundwater during migration and transformation resulting from acid in situ leaching of uranium in northern China.

• Horticultural Science & Technology
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• v.33 no.3
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• pp.390-395
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• 2015

The synthesis of chimeras is a breeding approach for horticultural crops. In our breeding program, a new diploid citrus chimera, named 'Hongrou Taoye' (Citrus sinensis [L.] Osbeck + Citrus unshiu Marc.), was found arising at the junction where a 'Taoye' sweet orange (C. sinensis) scion was grafted onto Satsuma mandarin (C. unshiu). As an artificial chimera, its fruit traits derived from the L1 cell layer, with juice color and carotenoid complement, in which ${\beta}$-cryptoxanthin accumulated predominantly, similar to those of Satsuma mandarin. By contrast, traits originating from the L2/L3 cell layer, including pollen, seed, and rind aroma characteristics, were the same as those of 'Taoye' sweet orange (the scion). SSR and cpSSR analyses showed that both nuclear and chloroplast genomes of the chimera were a combination of both donor parents. 'Hongrou Taoye' thus combined the valuable traits of both donor plants, and therefore has good potential in citrus fresh market.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.38 no.1
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• pp.14-19
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• 2012

Introduction: This study was conducted to evaluate ssrA expression resulting from adaptation of Escherichia coli (E. coli) to oral pathogens through signal exchange. Materials and Methods: Human cell lines Hep2 and HT29, wild-type E. coli (WT K-12), ssrA knock-out E. coli (${\Delta}K$-12), and Scleropages aureus (S. aureus) were used. A single culture consisting of Hep2, HT29, WT K-12, and ${\Delta}K$-12, and mixed cultures consisting of Hep2 and WT K-12, Hep2 and ${\Delta}K$-12, WT K-12 and S. aureus, ${\Delta}K$-12 and S. aureus, and Hep2, WT K-12, and S. aureus were prepared. For HT29, a mixed culture was prepared with WT K-12 and with WT K-12 and S. aureus. Total RNA was extracted from each culture with the resulting expression of ssrA, nuclear factor kappa-light-chain-enhancer of activated B cells (NF-${\kappa}B$), and p53 was evaluated by Reverse transcription polymerase chain reaction (RT-PCR). Results: The expression of ssrA in a single culture of WT K-12 was lower than that observed in the mixed culture of WT K-12 with S. aureus. Greater ssrA expression was observed in the mixed culture of WT K-12 with Hep2 than in the single culture of WT K-12. The expression of NF-${\kappa}B$ was higher in the mixed culture of Hep2 with ${\Delta}K$-12 than that in the mixed culture of Hep2 with WT K-12, and was lowest in the single culture of Hep2. The expression of ssrA was higher in the mixed culture of WT K-12 with Hep2 and S. aureus than in the mixed culture of WT K-12 with Hep2. Conclusion: These results suggest that ssrA plays an important role in the mechanism of E. coli adaptation to a new environment.

• Horticulture, Environment, and Biotechnology : HEB
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• v.59 no.6
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• pp.889-897
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• 2018

Currently, there is a lack of genetic markers capable of effectively detecting polymorphisms in Clematis. Therefore, we developed new markers to investigate inter- and intraspecific diversity in Clematis. Based on the complete chloroplast genome of Clematis terniflora, simple sequence repeats were explored and primer pairs were designed for all ten adequate repeat regions (cpSSRs), which were tested in 43 individuals of 11 Clematis species. In addition, the nuclear ITS region was sequenced in 11 Clematis species. Seven cpSSR loci were found to be polymorphic in the genus and serve as markers that can distinguish different species and be used in different genetic analyses, including cultivar identification to assist the breeding of new ornamental cultivars.

• Journal of Ecology and Environment
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• v.38 no.1
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• pp.47-56
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• 2015

Ailanthus altissima, which is recognized as an invasive tree in the Western world, has been widely observed in Japan. To investigate how A. altissima expanded within-population and to new populations within a region, 446 A. altissima trees were sampled from three separate sites (A, B, and C) including 35 distantly positioned patches, with three chloroplast DNA markers and nine nuclear microsatellite markers. We detected 2, 2, and 3 chloroplast haplotypes in sites A, B, and C, respectively. In addition, 271, 40, and 41 nuclear genotypes were detected in sites A, B, and C, respectively. The clonal richness value was 0.85, 0.78, and 0.53 in sites A, B, and C, respectively. Most trees with the same genotypes were distributed in the same patch, indicating that range expansion by asexual reproduction was limited to a maximum of 45 meters. According to autocorrelation analysis, the extent of nonrandom spatial genetic structure was approximately 0-2 km in sites A and C. KINGROUP analyses showed that 812, 74, and 111 nuclear genotype pairs were detected to have kinship in sites A, B, and C, respectively. Most nuclear genotype pairs were detected within the same patches or sites. These results indicate that the number of A. altissima trees gradually increased from seeds, some of which were produced by trees within sites, meaning that this species could regenerate naturally. This shows the need for the future management of A. altissima as an invasive species in Japan.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2022.09a
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• pp.66-66
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• 2022

속성수로 활용되는 버드나무속 식물들은 생식기관과 영양기관의 성장 시기가 달라 형태적 특성 평가를 위해 수년간의 조사 기간이 요구된다. 따라서 바이오매스 우수 버드나무속 교잡종 육성의 성공 여부를 조기 판별하기 위한 식별 기술이 필요하다. DNA 마커는 식물의 생장단계와 관련 없이 탐색할 수 있으며 환경에 영향을 받지 않는 장점이 있다. 식물의 계통 분류 시 주로 사용되는 엽록체 DNA는 유전자 염기서열의 변이가 비교적 크지 않은 장점이 있으나 대부분의 활엽수에서 모계를 통해 유전되는 특징이 있다. 하지만 종간 교잡종의 식별은 각각의 부모종과 구분할 수 있어야 하므로 본 연구는 엽록체 DNA가 아닌 핵 DNA를 대상으로 분석하였다. 본 연구의 목적은 호랑버들을 암나무로 갯버들을 수나무로 인공교배하여 육성된 종간 교잡종을 식별하는 핵 DNA 마커를 탐색하는 것이다. 이를 위해 버드나무속에서 개발된 총 35개의 nSSR (nuclear Simple Sequence Repeat) 마커를 대상으로 호랑버들과 갯버들, 종간 교잡종의 식별 가능성을 평가하였다. 분석 결과 호랑버들과 갯버들, 종간 교잡종 간 차이를 나타내는 2개의 핵 DNA 마커를 선발하였다. 따라서 선발된 핵 DNA 마커를 활용하여 호랑버들과 갯버들, 종간 교잡종의 조기 식별에 활용이 가능할 것으로 사료된다.

• Journal of Korean Society of Forest Science
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• v.104 no.4
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• pp.543-548
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• 2015

We studied the genetic impact of natural regeneration practices, such as Single seed tree, Group seed tree, Patch clear cutting and Alternate strip clear cutting systems, by comparing the nuclear microsatellite(nSSR) variation of post-practice natural regeneration one-year old seedlings of Pinus densiflora to that of pre-practice mature trees. The levels of genetic diversity of seedlings (A=13.6, $A_e$=4.3, $H_o$=0.571, $H_e$=0.597) were similar to those of mature trees (A=13.4, $A_e$=4.3, $H_o$=0.596, $H_e$=0.598) and the differences in the level of genetic diversity between seedlings and mature trees for each of the practices were not statistically significant. The degree of genetic differentiation between seedlings and mature trees was very low ($F_{ST}$=0.002) and the pairwise $F_{ST}$ values between seedlings and mature trees for all practices were less than 0.01. Overall, the natural regeneration practices appeared to have only minor impacts on the genetic diversity and the genetic composition in the studied P. densiflora stands. For a better understanding of the genetic effects of natural regeneration practices, subsequent studies such as temporal genetic variation of seedlings formed by crossing among post-practice mature trees should be considered.