• Korean Journal of Fisheries and Aquatic Sciences
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• v.17 no.5
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• pp.383-390
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• 1984

The present paper was carried out to elucidate the effect of salt-treatment and the addition of some food additives on the histamine formation and histidine decarboxylase activity in mackerel muscle during storage under different conditions. The histamine formation was inhibited by salting and histamine was hardly formed regardless of the brine concentraction during storage at $5^{\circ}C$. While, during storage at $25^{\circ}C$, the inhibitory effect upon the histamine formation and histidine decarboxylase activity was in proportion to the increase of the brine concentration. The addition of accidulants such as citric acid, malic acid and succinic acid inhibited the histamine formation and histidine decarboxylase activity. Especially, the histamine contents in the muscle added $10\%$ of citric acid and malic acid was below the critical concentration of poisoning for histamine during storage at $25^{\circ}C$ for 10 days. The histamine formation and histidine decarboxylase activity were inhibited by the $10\%$ addition of D-sorbitol, while there was no significant effect in the case of $5\%$ addition. Generally, the histamine content was increased with histidine decarboxylase activity, but didn't reveal the quantitative correlation ship with the enzyme activity.

• Journal of the Korean Society of Food Science and Nutrition
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• v.34 no.7
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• pp.1041-1051
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• 2005

In order to assure the safety of the seaweeds, we measured the contents of the trace metals in the seaweeds harvested from Korean coastal area. We collected 620 marine algal samples from fourteen areas, and then analyzed the trace metals such as Hg, Cd, Cr, Cu, Mn, Ni, Pb and Zn. The contents of Hg, Cd, Ni and Mn were higher in the seaweeds collected from Chungnam Taean area. The contents of Cr and Cu were higher in the seaweeds collected from Yeongdeok and Tongyeong area, respectively. And Pb and Zn were highly detected from the seaweeds of Ulsan area. The mean levels of trace metals were high in the order of Zn $(48.02\pm41.20{\mu}g/g)\;>\;Mn (34.63\pm38.95{\mu}g/g)\;>\;Cu(6.29\pm6.52{\mu}g/g)\;>\;Ni(2.17\pm4.00{\mu}g/g)\; >\;Cr(1.61\pm2.35{\mu}g/g)\;>\;Pb(1.28\pm2.37{\mu}g/g)\;>\; Cd(0.67\pm0.75{\mu}g/g)\;>\;Hg(0.02\pm0.02{\mu}g/g)$. Zn was consistently most abundant metal in all samples, followed by Mn and Cu, which are very important for human health. There were higher contents of Hg and Cd in brown algae, the contents of Cr, Cu, Mn, Ni and Pb in green algae, the content of Zn in red algae among them. Additionally, significant linear correlations were observed between a total 28 different pairs of metals, of them, the correlation factor between Cr and Ni showed the highest (r=0.374, p<0.001). The trace metal contents of seaweeds varied with habitats and kinds of samples, nevertheless they showed very safe level in edible seaweeds tested. Scytosiphon lomentaria, which has been known as a little use of food, have shown a clear selectivity for Cr and Pb. Among non-edible seaweeds, Sargassum thunbergii for both Cd and Mn, Lomentaria hakodatensis for Ni and Grateloupia prolongata for Zn have shown a clear selectivity, respectively. Therefore, these seaweeds could be useful as bioindicator for each trace metal pollution.

• The Korean Journal of Soil Zoology
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• v.6 no.1_2
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• pp.25-31
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• 2001

Oribatid mite communities in the process of litter decomposition were analyzed In Korean pine (Pinus koraiensis) forests of Namsan and Kwangreung, which were supposed to be under different environmental selective pressures. Oribatid mites were collected bimonthly from the litter bags (mesh size 0.4 mm, 1.7 mm) which was set up in the forest floor of study sites. This study had been carried out from Jan., 1997 to Sept., 1998. Species abundance of Kwangreung (mesh size 1.7 mm) was significantly higher than that of Namsan (mesh size 1.7 mm), but total no. of species did not exceed 30 species in all study sites. Concerning body length, medium sized oribatid mites (0.3-0.7mm) were more abundant than small ( < 0.3 mm) and large ( > 0.7 mm) sized mites. In Kwangreung, species whose body lengths were 0.2 mm to 0.5 mm were major group. However, a little larger species than Kwangreung's major group were dominant in Namsan. Sorenson similarity index and cluster analysis suggested that there were qualitative and quantitative differences in species composition in Namsan and Kwangreung. More species were collected in May through September than the other sampling times, but the pattern was rather different between first year and second year. Newly immigrant species were high in May in the first year and many of them regained on next year. Diversity indices suggested that species diversity of Kwangreung was higher than that of Namsan. Nearly 70% of total individual abundance was occupied by several dominant species in Namsan and Kwangreung . In the litter bags of mesh size 1.7 mm, the most dominant species was Trichogalumna nipponica in Namsan and Kwangreung, but in the litter bags of mesh size 0.4 mm in Kwangreung it was Ramusella sengbuschi which is smaller than T. nipponica. And important species related to litter decomposition were selected as follows; T. nipponica, Epidamaeus coreanus, Scheloribates latipes, Ceratozetes japonicus, Ramusella sengbuschi, Eohypochthonius crassisetiger, and Cultroribula lata.

• Journal of Korea Water Resources Association
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• v.35 no.1
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• pp.97-108
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• 2002

The use of land at the time of investigation of groundwater quality in the rapidly urbanized Bu-chon city is classified into 5 categories based on the change process of land use. The difference in groundwater quality according to the land use and its usage period is tested by non-parametric statistical procedures. The seven constituents of water quality with the highly frequent detection in the area for this study are used for the statistical test. The shallow groundwater quality within the areas of the same land use at the time of investigation varies significantly according to the period of land usage. The concentration of KMnO$_4$consumed and hardness is significantly higher in the old residential area (of more than 20 years old) than in the younger one (of less than 10 years old). The quality of the shallow groundwater is also significantly different among the three categories with the similar period of land usage (of more than 15 years old). The concentration of No$_3$-N, hardness and total solid is significantly higher in the residential area than in the agricultural one (namely, the area used as paddy fields 2 to 5 years ago). The median concentration of these constituents is 2.2 to 3.8 times higher in the residential area than in the agricultural one. The concentration of NO$_3$-N, KMnO$_4$, consumed and Cl is significantly higher in the industrial area than in the agricultural one. The median concentration of these constituents is 5.5 to 18 times higher in the industrial area than in the agricultural one. The concentration of KMnO$_4$consumed is significantly higher in the industrial area than in the residential area. The median concentration of these constituents is 12 times higher in the industrial area than in the residential one. The spatial distribution of shallow groundwater quality in the rapidly urbanized area is closely related to the period of land usage as well as the land use, which is presumed to be attributed to the difference in the concentration and leakage rate of the contaminants leaking from damaged sewer into shallow groundwater.

• Journal of Korea Water Resources Association
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• v.40 no.11
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• pp.887-898
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• 2007

A physically based semi-distributed model, SWAT was applied to the Chungju Dam upstream watershed in order to investigate the spatial and temporal characteristics of watershed sediment yields. For this, general features of the SWAT and sediment simulation algorithm within the model were described briefly, and watershed sediment modeling system was constructed after calibration and validation of parameters related to the runoff and sediment. With this modeling system, temporal and spatial variation of soil loss and sediment yields according to watershed scales, land uses, and reaches was analyzed. Sediment yield rates with drainage areas resulted in $0.5{\sim}0.6ton/ha/yr$ excluding some upstream sub-watersheds and showed around 0.51 ton/ha/yr above the areas of $1,000km^2$. Annual average soil loss according to land use represented the higher values in upland areas, but relatively lower in paddy and forest areas which were similar to the previous results from other researchers. Among the upstream reaches, Pyeongchanggang and Jucheongang showed higher sediment yields which was thought to be caused by larger area and higher fraction of upland than other upstream sub-areas. Monthly sediment yields at the main outlet showed same trend with seasonal rainfall distribution, that is, approximately 62% of annual yield was generated during July to August and the amount was about 208 ton/yr. From the results, we could obtain the uniform value of sediment yield rate and could roughly evaluate the effect of soil loss with land uses, and also could analyze the temporal and spatial characteristics of sediment yields from each reach and monthly variation for the Chungju Dam upstream watershed.

• Journal of Soil and Groundwater Environment
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• v.11 no.3
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• pp.31-42
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• 2006

Drought indices, such as PDSI (palmer Drought Severity Index), SWSI (Surface Water Supply Index) and SPI (Standardized Precipitation Index), have been developed to assess and forecast an intensity of drought. To find the applicability of groundwater level data to a drought assessment, a correlation analysis between SPI and groundwater levels was conducted for each time series at a drought season in 2001. The comparative results between SPI and groundwater levels of shallow wells of three national groundwater monitoring stations, Chungju Gageum, Yangpyung Gaegun, and Yeongju Munjeong, show that these two factors are highly correlated. In case of SPI with a duration of 1 month, cross-correlation coefficients between two factors are 0.843 at Chungju Gageum, 0.825 at Yangpyung Gaegun, and 0.737 at Yeongju Munjeong. The time lag between peak values of two factors is nearly zero in case of SPI with a duration of 1 month, which means that groundwater level fluctuation is similar to SPI values. Moreover, in case of SPI with a duration of 3 month, it is found that groundwater level can be a leading indicator to predict the SPI values I week later. Some of the national groundwater monitoring stations can be designated as DIW (Drought Index Well) based on the detailed survey of site characteristics and also new DIWs need to be drilled to assess and forecast the drought in this country.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.8 no.4
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• pp.392-400
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• 2003

We used an oxygen microelectrode to measure the vertical profiles of oxygen concentration in sediments located near point sources of organic matter. The measurements were carried out between 13th and 17th May, 2003, in semi-closed bay and coastal sediments in the central part of the South Sea. The measured oxygen penetration depths were extremely shallow and ranged from 1.30 to 3.80 mm. This suggested that the oxidation and reduction reactions in the early diagenesis should be studied at the mm depth scale. In order to estimate the oxygen consumption rate, we applied the one-dimension diffusion-reaction model to vertical profiles of oxygen near the sediment/water interface. Oxygen consumption rates were estimated to be between 10.8 and 27.6 mmol O$_2$ m$\^$-2/ day$\^$-1/(average: 19.1 mmol O$_2$ m$\^$-2/ day$\^$-1/). These rates showed a positive correlation with the organic carbon of the sediments. The corresponding benthic organic carbon oxidation rates calculated using an modified Redfield ratio (170/110) at the sediment/water interface were in the range of 89.5-228.1 mg C m$\^$-2/ day$\^$-1/(average: 158.0 mg C m$\^$-2/ day$\^$-1/). We suggest that these results are maximum values at the presents situation in the bay because the sampling sites were located near point sources of organic materials. This study will need to be carried out at many coastal sites and throughout the seasons to allow an understanding of the mechanisms of eutrophication e.g. the spatial distribution of oxygen consumption within the oxic zone and hypoxic conditions in the coastal sea.

• Korean Journal of Ecology and Environment
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• v.36 no.2 s.103
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• pp.181-190
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• 2003

An investigation was conducted on the aquatic environment of the Okchon Stream watershed six times from May to September 2002. The results of investigation revealed that variation of environmental factors were quite significant for each stream and reach, showing a significant difference between running water and stagnant water. Aquatic nutrients were relatively low in the upstream, gradually increasing as the influx of treated wastewater into the stream increased. This suggests that the point source definitely affected the nutrient content of the stream. In particular, the variations of SRP and $NH_4$ were very distinct in the watershed compared to other nutrients. Thus, it can be considered as a major factor in evaluating the effect of treated wastewater. Immediately after the influx of treated waste-water, the average content of SRP rose to 919.3 ${\mu}g$ P/l. This was a very effective level in the watershed, suggesting that the percentage of the nutrients in the water was controlled by the content of P. The constant supply of treated wastewater was found to be a critical factor in triggering the increase in chl-a in the embayment of the stream. With the proliferation of the blue-green algae, the content of chl- a ranged 234.5${\sim}$1,692.2 ${\mu}g/l$. The maximum standing crops exceeded $1.0{\times}10^6$ cells/ml in August, which was more than 200 times the level for red tide in the freshwater. This result was well reflected in other environmental factors, with 100% of AFDM/TSS reflecting the severity of water pollution by algae. Therefore, the reduction of P and N con-tents in the treated wastewater is critical in improving the aquatic environment of the stream as well as water quality management for the reservoir.

• Korean Journal of Food Science and Technology
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• v.38 no.1
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• pp.121-127
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• 2006

Microbial and nutritional characteristics of Kwangchun shrimp Jeotgal (salt-fermented shrimp) were assessed. Total mesophilic bacteria, coliforms, and S. aureus counts in Kwangchun shrimp Jeotgal were 3.48-5.42, 2.22-2.95, and 0.58-2.51 $log_{10}CFU/g$, respectively. Yeast and mold were detected only in Ohjeot (1.99 $log_{10}CFU/g$) and Yookjeot (1.47 $log_{10}CFU/g$). B. cereus, L. monocytogenes, Vibrio spp. and E. coli were not detected in Kwangchun shrimp Jeotgal, which contained abundant macrominerals (Ca, Mg, Na, K), with Na showing highest content. Palmitic acid content was higher than those of other saturated fatty acids. Eicosapentaenoic acid and docosahexaenoic acid contents were higher than those of other poly unsaturated fatty acids. Results showed Kwangchun shrimp Jeotgal is safe microbiologically with abundant nutritional components.

• Korean Journal of Remote Sensing
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• v.20 no.2
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• pp.77-89
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• 2004

The spatial and temporal variations of aerosol optical depth (AOD) over Northeast Asia regions have special importance in the aerosol research for estimation of aerosol radiative forcing parameters and climate change. Aerosol optical and physical properties (AOD and ${\AA}$ngstrom parameter) have been investigated by using Moderate Resolution Imaging Spectroradiometer (MODIS) and Total Ozone Mapping Spectrometer (TOMS) Aerosol Index (AI) to estimate aerosol characteristics over the study region during 2001. Additionally, aerosol characteristics over the Korean peninsular during Aerosol Characteristic Experiment in Asia (ACE-Asia) Intensive Observation Period (IOP) have been investigated by using satellite observations. The results showed that the daily-observed aerosol data indicate seasonal variations with relatively higher aerosol loading in the spring and very low during the winter. The typical Asian dust case showed higher AOD (>0.7) with lower Angstrom exponent (<0.5) and higher AI (>0.5) that is mainly due to the composition of coarse particles in the springtime. Mean AOD for 2001 at 4 different places showed 0.65$\pm$0.37 at Beijing, 0.31$\pm$0.19 at Gosan, 0.54$\pm$0.26 at Seoul, and 0.38$\pm$0.19 at Kwangju, respectively. An interesting result was found in the present study that polluted aerosol events with small size dominated-aerosol loading around the Korean peninsular are sometimes observed. The origin of these polluted aerosols was thought to East China. Aerosol distribution from satellite images and trajectory results shows the proof of aerosol transport. Therefore, aerosol monitoring using satellite data is very useful.