• Journal of Marine Bioscience and Biotechnology
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• v.1 no.2
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• pp.105-118
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• 2006

Isolation and Identification of fatty acid and volatile compounds in tuna fish oil were successfully carried out using supercritical carbon dioxide. Samples of the oil were extracted in a 56 ml semi-batch stainless steel vessel under conditions which ranged from 80 to 200 bar and 40 to $60^{\circ}C$ with carbon dioxide flows from 10 ml/min. Volatiles in the oil extracted from the samples with supercritical carbon dioxide were analyzed by gas chromatography, mass detector with canister system. The extracts were contained with various fatty acids, 57.0% of unsaturated fatty acids such as docosahexaenoic acid(DHA) and eicosapentaenoic acid(EPA), and 43.0% of saturated fatty acids. The aroma compounds in the oil showed over 129 peaks, of which 100 compounds were identified. Volatile components included 2,4-hepatadienal(fishy), dimethyldisulfide (unpleasant), dimethyltrisulfide (unpleasant) and 2-nonenal(fatty). The isolation efficiency of the volatile compounds from the samples was 99.4% at $50^{\circ}C$ and 200 bar.

• Journal of Life Science
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• v.22 no.3
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• pp.366-372
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• 2012

This study was conducted to estimate the extent of linkage disequilibrium (LD) and effective population size using whole genomic single nucleotide polymorphisms (SNP) genotyped by DNA chip in Hanwoo. Using the blood samples of 35 young bulls born from 2005 to 2008 and their progenies (N=253) in a Hanwoo nucleus population collected from Hanwoo Improvement Center, 51,582 SNPs were genotyped using Bovine SNP50 chips. A total of 40,851 SNPs were used in this study after elimination of SNPs with a missing genotyping rate of over 10 percent and monomorphic SNPs (10,730 SNPs). The total autosomal genome length, measured as the sum of the longest syntenic pairs of SNPs by chromosome, was 2,541.6 Mb (Mega base pairs). The average distances of all adjacent pairs by each BTA ranged from 0.55 to 0.74 cM. Decay of LD showed an exponential trend with physical distance. The means of LD ($r^2$) among syntenic SNP pairs were 0.136 at a range of 0-0.1 Mb in physical distance and 0.06 at a range of 0.1-0.2 Mb. When these results were used for Luo's formula, about 2,000 phenotypic records were found to be required to achieve power > 0.9 to detect 5% QTL in the population of Hanwoo. As a result of estimating effective population size by generation in Hanwoo, the estimated effective population size for the current status was 84 heads and the estimate of effective population size for 50 generations of ancestors was 1,150 heads. The average decreasing rates of effective population size by generation were 9.0% at about five generations and 17.3% at the current generation. The main cause of the rapid decrease in effective population size was considered to be the intensive use of a few prominent sires since the application of artificial insemination technology in Korea. To increase and/or sustain the effective population size, the selection of various proven bulls and mating systems that consider genetic diversity are needed.

• Journal of Life Science
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• v.21 no.2
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• pp.292-299
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• 2011

This study compared volatile flavor profiles of 4 commercial vinegar beverages (Italian vinegar beverage (IVB), Japanese vinegar beverage (JVB), Japanese Yuzu-Ponz (JYP), and Korean white wine vinegar beverage (KWVB)). Flavor components of vinegar beverages (VBs) were determined using SPME/GC/MSD. The profiles of VBs were as follows; IVB (11 acids, 17 esters, 10 alcohols, 8 aldehydes, 3 terpenes, 4 aromatic hydrocarbons, 9 ketones), JVB (7 acids, 8 esters, 9 alcohols, 7 aldehydes, 13 terpenes, 7 aromatic hydrocarbons, 1 ketones, 3 miscellaneous compounds), JYP (3 acids, 12 esters, 8 alcohols, 7 aldehydes, 63 terpenes, 6 aromatic hydrocarbons, 2 ketones, 5 miscellaneous compounds), KWVB (10 acids, 10 esters, 9 alcohols, 8 aldehydes, 2 terpenes, 5 aromatic hydrocarbons, 4 ketones, 2 miscellaneous compounds). IVB and JVB showed similar flavor compositions (acids, ketones and esters in particular), whereas major components in JYP and KWVB were terpenes (79.6%) and acids (81.0%), respectively. Five compounds including 2-phenylethyl acetate (floral, fruity, sweet odor), 2-phenylethanol (floral, rose odor), vitispirane (fruity odor), geranylacetone (fragrant odor) and acetic acid were identified as major components in balsamic vinegar beverages.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.8 no.2
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• pp.78-93
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• 2003

To investigate seasonal variation and structure of the microbial community in Kyeonggi Bay, abundance and carbon biomass of nano-and micrzooplankton were evaluated in relation to size fractionated chlorophyll-a concentration, through the monthly interval sampling from December 1997 to November 1998. Communities of nano-and microzooplankton were classified into 4 groups such as heterotrophic nanoflagellate(HNF), ciliates, heterotrophic dinoflagellates(HDF) and zooplankton nauplii. Abundance and carbon biomass of HNF ranged from 380 to 4,370 cells ml-1(average 1,340$\pm$130 cells ml-1) and from 0.63 to 12.4 $\mu\textrm{g}$C 1-1(average 4.35$\pm$0.58 $\mu\textrm{g}$C 1-1), respectively. Abundance and carbon biomass of ciliates ranged from 331 to 44,571 cells ml-1(average 3,526$\pm$544 cells ml-1) and from 1.3 to 119.7 $\mu\textrm{g}$C 1-1(average 13.7$\pm$3.0 $\mu\textrm{g}$C 1-1), respectively. Abundance and carbon biomass of HDF ranged from 88 to 48,461 cells 1-1(average 9,034$\pm$2,347 cells 1-1) and from 0.05 to 54.05 $\mu\textrm{g}$C 1-1(average 6.9$\pm$2.4 $\mu\textrm{g}$C 1-1), respectively. Abundance and carbon biomass of zooplankton nauplii ranged from 5 to 546 indiv. 1-1(average 83$\pm$15 indiv. 1-1) and from 0.17 to 43.2 $\mu\textrm{g}$C 1-1(average 6.3$\pm$1.2 $\mu\textrm{g}$C 1-1), respectively. Eash component of microbial biomass was not different from tidal cycle except tintinnids group. Depth integrated nano-and microzooplankton biomass ranged from 124 to 1,635 mgC m-2(average 585$\pm$110 mgC m-2) and was highest in March and May. The relative contribution of each component to the nano-and microzooplankton showed difference according to seasons. Community structure of nano-and microzooplankton was dominated by planktonic ciliate group. During the study period, carbon biomass of nano-and microzooplankton was strongly positively correlated with size fractionated chlorophylla-a. It implied that prey-predator relationship between microzooplankton and phytoplankton was important in the pelagic ecosystem of Kyeonggi Bay.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.23 no.1
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• pp.1-19
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• 2018

In order to compare significant wave height (SWH) data from multi-satellites (GFO, Jason-1, Envisat, Jason-2, Cryosat-2, SARAL) and SWH measurements from Ieodo Ocean Research Station (IORS), we constructed a 12 year matchup database between satellite and IORS measurements from December 2004 to May 2016. The satellite SWH showed a root mean square error (RMSE) of about 0.34 m and a positive bias of 0.17 m with respect to the IORS wave height. The satellite data and IORS wave height data did not show any specific seasonal variations or interannual variability, which confirmed the consistency of satellite data. The effect of the wind field on the difference of the SWH data between satellite and IORS was investigated. As a result, a similar result was observed in which a positive biases of about 0.17 m occurred on all satellites. In order to understand the effects of topography and the influence of the construction structures of IORS on the SWH differences, we investigated the directional dependency of differences of wave height, however, no statistically significant characteristics of the differences were revealed. As a result of analyzing the characteristics of the error as a function of the distance between the satellite and the IORS, the biases are almost constant about 0.14 m regardless of the distance. By contrast, the amplitude of the SWH differences, the maximum value minus the minimum value at a given distance range, was found to increase linearly as the distance was increased. On the other hand, as a result of the accuracy evaluation of the satellite SWH from the Donghae marine meteorological buoy of Korea Meteorological Administration, the satellite SWH presented a relatively small RMSE of about 0.27 m and no specific characteristics of bias such as the validation results at IORS. In this paper, we propose a conversion formula to correct the significant wave data of IORS with the satellite SWH data. In addition, this study emphasizes that the reliability of data should be prioritized to be extensively utilized and presents specific methods and strategies in order to upgrade the IORS as an international world-wide marine observation site.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.23 no.2
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• pp.76-90
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• 2018

To determine the distribution of mercury (Hg) in the coastal surface sediments around the Korean peninsula, the baseline concentration of Hg was estimated, the extent of contamination was assessed, and the factors controlling the distribution were discussed. The concentrations of Hg in surface sediments were significantly high in Jinhae-Masan Bay in the South Sea, Ulsan-Onsan Bay and Yeongil Bay in the East Sea, but Hg in other sediments showed a similar distribution to Cs and relatively very low concentration between 0.21 and $39.5{\mu}g/kg$ ($13.6{\pm}7.80{\mu}g/kg$). Compared to the sediment quality guidelines in Korea, 8 % of the surface sediments (n=282) analyzed in this study exceeded the values of the threshold effects level (TEL), and six sediments collected around Onsan Port were higher than the value of the probable effects level (PEL). The contamination levels of Hg were assessed by the enrichment factors using the baseline concentration (2.06Cs+1.75) based on the residual analysis from the linear regression line for Cs, and further, factors controlling the distribution of Hg were discussed by the comparison with geochemical substances depending upon the Hg enrichment level. Hg concentrations were correlated well with Cs concentration in the range of less than 1.69 of EF implying grain size control, while in the range of 1.69 and 4.03 Hg concentrations were correlated well with Fe oxyhyroxide and organic carbon contents, which indicates Hg was enriched by superior sorption capability. On the meanwhile, samples with higher EFs (4.03 to 74.9) showed fairly positive correlations with other metals (Cu, Zn, Pb) rather than geochemical substances. For samples in Youngil Bay and Ulsan-Onsan Bay (n=30), Hg concentrations were correlated only with other metals rather than geochemical substances implying simultaneous supply of metal particles from metal refineries. But samples at Gosung, Sokcho and Uljin coast were correlated well with organic carbon even though they had high EFs. In addition, samples in Jinhae-Masan Bay with high contents of S were enriched by relatively high sulfide formation.

• Horticultural Science & Technology
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• v.28 no.3
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• pp.403-408
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• 2010

This study was carried out to investigate the physiological responses of $Rhododendron$ $mucronulatum$ Turcz. and $R.$ $indicum$ (L.) Sweet seedlings with 0%, 35%, 55% and 75% shading of full sunlight in polyethylene film house. The shading treatments were performed during the late growth season for each species (from Sept. 9 to Nov. 5, 2008). The shading treatment was effective in reducing the daily temperature by 0.9 to $1.7^{\circ}C$ during September and by 0.8 to $1.7^{\circ}C$ during October. Before the shading treatments, the water content of $R.$ $mucronulatum$ and $R.$ $indicum$ amounted to 68.5% and 66.3%, respectively. The water contents of two species after 75% shading treatment period decreased to 66.2% (3.4% reduction) and 65.9% (0.6% reduction), respectively. Notably, both species had a similar tendency indicating less reduction rate of water content with 75% shading. $R.$ $indicum$ showed higher photosynthetic capacity with higher level of shading, and its photosynthetic capacity reached the highest level ($9.63{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$). On the other hand, shading-treated $R.$ $indicum$ showed higher intercellular $CO_2$ concentration, stomatal conductance and transpiration rate (55% shading > 35% shading > 75% shading) than non-treated ones. In addition, non-treated seedlings showed higher water use efficiency than treated ones. In particular, it was found that the leaf color of $R.$ $mucronulatum$ turned equivalent to purple under full sunlight, while its leaf color kept equivalent more to green with higher level of shading, as evidenced even in naked eyes. According to comprehensive analysis using Munsell Color Chart on potential leaf color variations of $R.$ $mucronulatum$ depending on the level of shading, it was found that relatively many leaf colors under full sunlight were equivalent to R (red) and Y (yellow) chart, while relatively many leaf colors with higher level of shading were equivalent to G (green) and Y chart, where the latter still showed green color.

• Korean Journal of Ecology and Environment
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• v.35 no.3 s.99
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• pp.160-171
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• 2002

The impact of summer monsoon on water quality of the lower Nakdong River was evaluated during the summer (June-August) in 1997. Several limnological variables were measured in the interval of $1{\sim}3$ day using an automatic monitoring system (Hydrolab $Recorder^{TM}$) to detect water quality changes caused by rainfall on onehour basis. During the monsoon period (from late June to mid July), 5 times of major rainfall events of >50 mm were recorded in the river basin. Dynamic changes of water quality were observed during the monsoon, and the first rainfall event (June$25{\sim}27$) had a significant influence on the water quality at the lower part of the river. All Parameters were largely changed due to the first rain event, and the changed level was maintained until the end of monsoon period. Nutrient concentrations and turbidity increased and values of the other parameters were declined as a result of water dilution. This rainfall event, Changma, is a meteorological phenomenon caused by the East-Asian monsoon climate. The magnitude and frequency of the rainfall during the early monsoon play an important role in change of water quality and ecosystem characteristics of large river systems.

• Korean Journal of Ecology and Environment
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• v.48 no.3
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• pp.176-187
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• 2015

In this study, we hypothesized that the size of wintering crane population would change due to the climate factors. We assumed that wintering population size would differ by climate values in January, which is the coldest period in year. Especially, White-naped cranes were able to choose wintering site between Cheorwon and other alternative place where snow coverage had low influence, differing from Red crowned cranes. For this reason, we predicted the population size of White-naped cranes would fluctuate according to the extent of snow coverage in Cheorwon. Therefore we used snow coverage data based on MODIS and climate data from KMA (Korea Meteorological Administration) that are generally used. We analyzed the crane's population size in Cheorwon in January from 2002 to 2014. The temperature in the Cheorwon increased from 2002 to wintering period in 2007~ 2008 and went down, showing the lowest temperature in 2011~ 2012. With this phenomenon, warmth index showed the similar pattern with temperature. Amount of newly accumulated snow (the amount of snow that fallen from 0:01 am to 11:29 pm in a day) was low after 2002, but rapidly increased in 2010~ 2011 and 2011~ 2012. The area of snow coverage rapidly declined from 2002 to 2005~ 2006 but suddenly expanded in wintering period in 2009~ 2010 and 2010~ 2011. Wintering population size of the White-naped cranes decreased as snow coverage area increased in January and the highest correlation was found between them, compared to the other climatic factors. However, the number of individuals of Red crowned cranes had little relationship with general climate factors including snow cover range. Therefore it seems that population size of the Red crowned crane varied by factors related with habitat selection such as secure roosting site and area of foraging place, not by climatic factors. In multiple regression analysis, wintering population of White-naped cranes showed significant relationship with logarithmic value of snow cover range and its period. Therefore, it suggests that the population size of the White-naped crane was affected by snow cover range n wintering period and this was because it was hard for them to find out rice grains which are their main food items, buried in snow cover. The population size variation in White-naped cranes was caused by some individuals which left Cheorwon for Izumi where snow cover had little influence on them. The wintering population in Izumi and Cheorwon had negative correlation, implying they were mutually related.

• Korean Journal of Ecology and Environment
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• v.49 no.4
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• pp.279-288
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• 2016

Stable Isotope Analysis(SIA) of carbon and nitrogen is useful tool for the understanding functional roles of target organisms in biological interactions in the food web. Recently, mixing model based on SIA is frequently used to determine which of the potential food sources predominantly assimilated by consumers, however, application of model is often limited and difficult for non-expert users of software. In the present study, we suggest easy manual of R software and package SIAR with example data regarding selective feeding of crustaceans dominated freshwater zooplankton community. We collected SIA data from the experimental mesocosms set up at the littoral area of eutrophic Chodae Reservoir, and analyzed the dominant crustacean species main food sources among small sized particulate organic matters (POM, <$50{\mu}m$), large sized POM (>$50{\mu}m$), and attached POM using mixing model. From the results obtained by SIAR model, Daphnia galeata and Ostracoda mainly consumed small sized POM while Simocephalus vetulus consumed both small and large sized POM simultaneously. Copepods collected from the reservoir showed no preferences on various food items, but in the mesocosm tanks, main food sources for the copepods was attached POM rather than planktonic preys including rotifers. The results have suggested that their roles as grazers in food web of eutrophicated reservoirs are different, and S. vetulus is more efficient grazer on wide range of food items such as large colony of phytoplankton and cyanobacteria during water bloom period.