• Korean Journal of Plant Taxonomy
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• v.51 no.3
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• pp.192-197
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• 2021

In the flora of Korea, Carex L. is one of the most species-rich genera. Among nearly 157 Carex taxa, less than 30 have had chromosome numbers reported. We report the meiotic chromosome numbers of eight Carex taxa from Korean populations, which include the first count for C. accrescens Ohwi (n = 37_II) and the first chromosome investigations of Korea populations for three taxa: C. bostrychostigma Maxim. (n = 22_II), C. lanceolata Boott (n = 36_II), and C. paxii Kuk. (n = 38_II). In most species, chromosome counts observed in the study are included in the variation ranges of previous chromosome numbers. However, C. bostrychostigma Maxim. (n = 22_II) and C. planiculmis Kom. (n = 29_II) are assigned new chromosome numbers. Carex is known to have holocentric chromosomes, lacking visible primary constrictions and exhibiting great variance in its chromosome number. Further investigations of the diversity of Carex chromosomes will provide basic information with which to understand the high species diversity of the genus.

• Journal of Life Science
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• v.25 no.3
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• pp.257-262
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• 2015

The genetic variability of four species of the genus Zoysia collected from South Korea was analyzed using an inter-simple sequence repeat (ISSR) marker system. Polymerase chain reactions (PCR) with eight ISSR primers generated 86 amplicons, 76 (87.1%) of which were polymorphisms. The polymorphism information content (PIC) value of the ISSR marker system was 0.848. The percentage of polymorphic loci (P_p) ranged from 41.2% to 44.7%. Nei’s gene diversity (H) ranged from 0.149 to 0.186, with an average overall value of 0.170. The mean of Shannon’s information index (I) value was 0.250. Total genetic diversity values (H_T) varied between 0.356 (ISSR-1) and 0.418 (ISSR-16), for an average overall polymorphic loci of 0.345. Interlocus variation in within-species genetic diversity (H_S) was low (0.170). On a per-locus basis, the proportion of total genetic variation due to differences among species (G_ST) was 0.601. This indicated that about 60.1% of the total variation was among species. Thus, about 39.9 of genetic variation was within species. The estimate of gene flow, based on G_ST, was very low among species of the genus Zoysia (N_m = 0.332). The phylogenic tree showed three distinct groups: Z. macrostachya and Z. tenuifolia clades and other species were formed the separated clusters. In conclusion, the ISSR assay was useful for detecting genetic variation in the genus Zoysia, and its discriminatory power was comparable to that of other genotyping tools.

• Fisheries and Aquatic Sciences
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• v.26 no.8
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• pp.470-481
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• 2023

Algal overgrowth in shrimp culture ponds can affect the quality of the aquatic environment, thereby adversely affecting the shrimp and causing economic losses. The objective of this study was to evaluate the variation in phytoplankton composition in intensive shrimp ponds in Bac Lieu province, Vietnam. Phytoplankton samples were collected in three black tiger shrimp (Penaeus monodon) ponds and three whiteleg shrimp (Litopenaeus vannamei) ponds. The collected data were analyzed using SPSS and canonical correlation analysis softwares. In total, 75 species of phytoplankton were recorded in black tiger shrimp ponds and 64 species in whiteleg shrimp ponds. Diatoms had the highest species diversity with 29-30 species (39%-47%), followed by green algae with 9-19 species (14%-25%); species numbers of other phyla varied from 5-12 (8%-16%). The total number of phytoplankton species throughout the study varied from 34-50 species. Algal density was relatively high and ranged from 497,091-2,229,500 ind./L and 1,301,134-2,237,758 ind./L in black tiger shrimp and whiteleg shrimp ponds, respectively. The diatom density tended to increase during the final stage of the production cycle in black tiger shrimp ponds. Blue-green algae and dinoflagellates also increased in abundance at the end of the cycle, which can affect shrimp growth. Diatoms were significantly positively correlated with pH, salinity, total ammonia nitrogen, and nitrate (NO₃^-) concentrations (p < 0.05). Blue-green algae and dinoflagellates were positively correlated with salinity, phosphate (PO₄^3-), and NO₃^-. Algal species diversity was lower in the whiteleg shrimp ponds than in the black tiger shrimp ponds. Several dominant algal genera were recorded in the shrimp ponds, including Nannochloropsis, Gyrosigma, Chaetoceros, Alexandrium, and Microcystis. The results of this study provide basic data for further investigations, and they contribute to the management of algae in brackish-water shrimp ponds.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.23 no.3
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• pp.63-79
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• 2020

The present study was to investigate the growth response and nutrient absorption in three willow species (Salix gracilistyla, S. koreensis and S. chaenomeloides) treated with nitrogen source (NH₄⁺:NO₃^- rate; 200:0, 150:50, 100:100, 50:150, 200:0) for a period of 90days. The height, dry weight and chlorophyll contents of three species of willows were found to be highest at 50:150 (NH₄⁺:NO₃^-) treatment. NO₃^--N was more effective than NH₄⁺-N in the early growth of three species of willows. The increase in percentage of NO₃^--N handling, T-N, NO₃^--N in plant tissue increased. The analysis of C, N and mineral content in various parts revealed that the amounts of C, N, K, Ca and Mg were higher in leaves than those in the stems and the roots. However, the amount of NO₃^--N and P were higher in roots than those in the leaves and the stems. Salix koreensis was excellent, followed by S. chaenomeloides and S. gracilistyla in absorption of nitrate nitrogen. Higher percentage of NO₃^--N, the amounts of T-N, NO₃^--N, P₂O₅, K, Na, Ca, and pH in soil were decreased.

• Journal of the Korean Society of Combustion
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• v.19 no.1
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• pp.39-44
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• 2014

A short reaction mechanism for premixed $CH_4/CHF_3/Air$ flames was developed with a reduction method of the combined application of simulation error minimization (SEM) which included connectivity method and principal component analysis. It consisted of 43 species and 403 elementary reactions at the condition of less than 5% of maximum error. The calculation time operated with a short mechanism was over 5 times faster than one with a detailed reaction mechanism. Good agreement was found between the flame speeds calculated by the short reaction mechanism and those by the detailed reaction mechanism for the entire range of $CHF_3/CH_4$ mole ratios and equivalence ratios. In addition excellent agreements were determined for the profiles of temperature, species concentration, and the production rates of the various species. So the short reaction mechanism was able to accurately predict the flame structure for premixed $CH_4/CHF_3/Air$ flames.

• Journal of Species Research
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• v.2 no.1
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• pp.15-54
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• 2013

Surveys on Jeju-do (Quelpart Isl.) unearthed about 40 earthworm species or sub-species. Several considered new to science are described. Only a dozen were previously known and these are taxonomically reviewed. The two most commonly recorded in surveys by S. Kobayashi in the 1930s were Drawida anchingiana Chen, 1933 and Metaphire quelparta (Kobayashi, 1937), neither recently relocated. Morphologically similar taxa, supported with DNA barcodes, for Moniligastridae, are Drawida anchingiana seogwipo, D. anchingiana halla and D. iucn spp. or sub-spp. nov. For Megascolecidae, new taxa and synonyms are: Amynthas arx and A. aucklandis spp. nov. that have seminal grooves rather than the eversible male pores of Metaphire plus Amynthas simplex is another new species. Amynthas sangumburi Hong & Kim, 2002 is recognized as a probable new synonym within the A. corticis (Kinberg, 1867) species-group while Amynthas corticis saeseum sub-sp nov. is described. Amynthas gracilis (Kinberg, 1867) is a new record from Jeju and Korea (with A. bouchei, A. omodeoi and A. edwardsi all by Zhao & Qiu, 2009 possible synonyms of this species group from China) with a Jejuan sub-species, A. gracilis insularum, sub-sp. nov. Presence on Jeju of Amynthas carnosus (Goto & Hatai, 1899) is confirmed (its further new synonyms are Chinese A. fuscus Qiu & Sun, 2012 and A. taiwumontis Shen et al., 2013), as is A. micronarius (Goto & Hatai, 1898) (with new synonym A. montanus Qiu & Sun, 2012 also an invalid secondary homonym). Amynthas phaselus maculosus (Hatai, 1930) is in new combination with A. kamitai (Kobayashi, 1934) and A. minjae Hong, 2001 syns. nov. Two newly described Metaphire quelparta sub-spp are M. q. seogwipo and M. q. valhalla these being supported with DNA barcodes despite the nominal taxon not yet being confirmed.

• Journal of Microbiology and Biotechnology
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• v.31 no.8
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• pp.1154-1162
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• 2021

The transcriptional capacities of target genes are strongly influenced by promoters, whereas few studies have focused on the development of robust, high-performance and cross-species promoters for wide application in different bacteria. In this work, four novel promoters (P_k.rtufB, P_k.r1, P_k.r2, and P_k.r3) were predicted from Ketogulonicigenium robustum and their inconsistency in the -10 and -35 region nucleotide sequences indicated they were different promoters. Their activities were evaluated by using green fluorescent protein (gfp) as a reporter in different species of bacteria, including K. vulgare SPU B805, Pseudomonas putida KT2440, Paracoccus denitrificans PD1222, Bacillus licheniformis and Raoultella ornithinolytica, due to their importance in metabolic engineering. Our results showed that the four promoters had different activities, with P_k.r1 showing the strongest activity in almost all of the experimental bacteria. By comparison with the commonly used promoters of E. coli (tufB, lac, lacUV5), K. vulgare (Psdh, Psndh) and P. putida KT2440 (JE111411), the four promoters showed significant differences due to only 12.62% nucleotide similarities, and relatively higher ability in regulating target gene expression. Further validation experiments confirmed their ability in initiating the target minCD cassette because of the shape changes under the promoter regulation. The overexpression of sorbose dehydrogenase and cytochrome c551 by P_k.r1 and P_k.r2 resulted in a 22.75% enhancement of 2-KGA yield, indicating their potential for practical application in metabolic engineering. This study demonstrates an example of applying bioinformatics to find new biological components for gene operation and provides four novel promoters with broad suitability, which enriches the usable range of promoters to realize accurate regulation in different genetic backgrounds.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.20 no.1
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• pp.43-63
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• 2022

The aim of this review is to communicate some essential knowledge of the underlying mechanism of the corrosion of structural containment alloys during molten salt reactor operation in the context of prospective online monitoring in future MSR installations. The formation of metal halide species and the progression of their concentration in the molten salt do reflect containment corrosion, tracing the depletion of alloying metals at the alloy salt interface will assure safe conditions during reactor operation. Even though the progress of alloying metal halides concentrations in the molten salt do strongly understate actual corrosion rates, their prospective 1^st order kinetics followed by near-linearly increase is attributed to homogeneous matrix corrosion. The service life of the structural containment alloy is derived from homogeneous matrix corrosion and near-surface void formation but less so from intergranular cracking (IGC) and pitting corrosion. Online monitoring of corrosion species is of particular interest for molten chloride systems since besides the expected formation of chromium chloride species CrCl₂ and CrCl₃, other metal chloride species such as FeCl₂, FeCl₃, MoCl₂, MnCl₂ and NiCl₂ will form, depending on the selected structural alloy. The metal chloride concentrations should follow, after an incubation period of about 10,000 hours, a linear projection with a positive slope and a steady increase of < 1 ppm per day. During the incubation period, metal concentration show 1^st order kinetics and increasing linearly with time^1/2. Ideally, a linear increase reflects homogeneous matrix corrosion, while a sharp increase in the metal chloride concentration could set a warning flag for potential material failure within the projected service life, e.g. as result of intergranular cracking or pitting corrosion. Continuous monitoring of metal chloride concentrations can therefore provide direct information about the mechanism of the ongoing corrosion scenario and offer valuable information for a timely warning of prospective material failure.

• Journal of Korean Society for Atmospheric Environment
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• v.20 no.1
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• pp.119-128
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• 2004

The nitrate concentrations in PM$_{2.5}$ and TSP measured at Gosan, Jeju Island, Korea, between March 1998 and February 2002, are discussed. Especially, the characteristics of high nitrate concentration days were analyzed. High nitrate concentration cases in PM$_{2.5}$ were highly correlated with anthropogenic species such as NH$_4$$^{[-10]}$ , and high nitrate concentration cases in TSP were highly correlated with crustal species such as nss-Ca$^{2+}$ and nss -Mg$^{2+}$ Backward trajectory analysis results show the cases of high correlation between nitrate and anthropogenic species occurred when the air parcels moved from China, and the cases of high correlation between nitrate and crustal species occurred when the air parcels moved from Mongolia. Also, high nitrate concentration cases occurred most often in spring (65%) when the air parcels moved from Mongolia and China.ina.

• Journal of Korean Society for Atmospheric Environment
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• v.18 no.4
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• pp.317-325
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• 2002

An air pollution monitoring station has been operated at Tokchok Island since April 1999 to characterize the background atmosphere in the vicinity of the Yellow Sea. In this study, eight chemical species in PM$_{2.5}$ and three gaseous species were analyzed. A total of 53 samples were collected for the analysis of PM$_{2.5}$ and gaseous species from April, 1999 to April, 2001. The overall mean mass concentration of PM$_{2.5}$ was 20.8 $\mu\textrm{g}$/㎥ and the eight soluble ionic species accounted for about 46.8% of PM$_{2.5}$ mass. Approximately 80% of samples appeared to experience the chloride loss effect. Air pollutant sources of PM$_{2.5}$ measured at Tokchok Island were qualitatively identified by the principal component analysis. It was found that five principal components are secondary aerosol, soil, incineration, phase change of nitrate, and ocean.and ocean.