• Journal of the Korean Society for Marine Environment & Energy
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• v.12 no.4
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• pp.227-234
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• 2009

Using a finite volume ocean circulation model based on an unstructured grid (FVCOM), we studied the structure of a fresh water bulge that influences on the Region Of Freshwater Influence. Fresh water discharged a river forms a coastal boundary current to the righthand side and a cyclonically circulation freshwater bulge that grows with time. In the middle of the bulge, vertical motions bring fresh water to the bottom. When tidal motions are included, the bulge disappears while the boundary currents becomes wider. Through a simple comparison of areas occupied low salinity water we quantified vertical and horizontal mixing due to the tide and showed that the tidal motion enhances the vertical mixing. During the first few tidal cycles right after the onset of the river discharge, due to tidal excursion the horizontal mixing becomes stronger. The vertical mixing by the tide mixes the fresh water After a certain time the water around the river mouth is well mixed and the horizontal excursion of the fresh water near the river mouth does not have much effect on the horizontal mixing. When there is no tidal motion horizontal mixing is mainly by the inertial instability at the surface and the horizontal mixing becomes stronger over time.

• Journal of the Korean earth science society
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• v.36 no.3
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• pp.199-209
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• 2015

The Atlantic meridional overturning circulation (AMOC), driven by high density water sinking around Greenland serves as a global climate regulator, because it transports heat and materials in the climate system. We analyzed the mechanism of AMOC on a decadal time scale simulated with the HadGEM2-AO model. The lead-lag regression analysis with AMOC index shows that the decadal variability of the thermohaline circulation in the Atlantic Ocean can be considered as a self-sustained variability. This means that the long-term change of AMOC is related to the instability which is originated from the phase difference between the meridional temperature gradient and the ocean circulation. When the overturning circulation becomes stronger, the heat moves northward and decreases the horizontal temperature-dominated density gradients. Subsequently, this leads to weakening of the circulation, which in turn generates the anomalous cooling at high latitudes and, thereby strengthening the AMOC. In this mechanism, the density anomalies at high latitudes are controlled by the thermal advection from low latitudes, meaning that the variation of the AMOC is thermally driven and not salinity driven.

• The Korean Journal of Food And Nutrition
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• v.27 no.6
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• pp.1006-1013
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• 2014

This study is aimed at examining the usefulness of mugwort as an alternative of western herb by making widely known tomato sauce with mugwort powder added, the ingredient that has a bio-active substance. The control group showed the highest percentage of water from tomato sauce, 89.24%. The sauce with mugwort added in by 2% showed the lowest pH, 4.55. The brightness L value for chromaticity got lower significantly (p>0.001) as the amount of added mugwort increased, and red a value and yellow b value were high in the control group for 18.06 and 16.84 respectively, and got reduced as the amount of added mugwort increased. The salinity was the highest in the sauce mugwort added in by 2% for 1.02. Sugar content and reducing sugar were the lowest in the sauce mugwort added in by 2% for 9.49 and 56.01. As measuring total count change, no microorganism was found until $10^{th}$ day of storage, and was 0% $1.7{\times}10^3CFU/mL$ on the $15^{th}$ day, and no microorganism was found in the 1.5% and 2% added groups. Lastly for 60 days of storage, the control group without mugwort showed the highest microorganism count for $3.1{\times}10^8CFU/mL$ In a sensory test, color was in the 1% added group was 5.28, higher than the control group which showed 4.78, but there was no significant difference. Taste was rated most highly in the 1.5% added group for 5.65. After taste was also rated most highly in the 1.5% added group for 5.8. Overall preference was the highest in the 1% added group for 5.79. From the results, tomato sauce with mugwort added in showed the high storage capacity and was rated highly in the preference test. The possibility of the alternative of western spice and the potential to use Korean spice for other western spice were observed again.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.27 no.3
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• pp.215-222
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• 1994

Kang-Nung sik-hae is a traditional Korean fermented fish product which has remained in existence in Kang-Nung district. In order to preserve the traditional culture of Kang-Nung sik-hae and develop it as a commercial product, the property changes of sik-hae were investigated at different fermentation temperatures and periods. The chemical changes during the fermentation of squid(Todarodes pacificus) sik-hae were studied at different fermentation temperatures and periods. The amounts of proximate compositions and salinity did not change significantly at all fermentation temperatures and periods. The value of pH decreased with increasing storage period at all fermentation temperatures except at $5^{\circ}C$, whereas that of lactic acid at all fermentation temperatures increased. The amount of total arginine increased slightly up to 10-day of storage and decreased after that. The amount of $NH_2-N$ increased rapidly up to 15-day of storage at all temperatures and increased slightly after that. The amount of TMAO decreased significantly at $15^{\circ}C\;and\;20^{\circ}C$ and slightly at $5^{\circ}C\;and\;10^{\circ}C$, whereas that of TMA increased significantly at $20^{\circ}C$ up to 5-day of storage and decreased slightly after that. At all experimental temperatures except $5^{\circ}C$, the amount of TMA increased or fluctuated in proportion to the increase in fermentation periods. Inosine and hypoxanthine were the main components of nucleotides and their related compounds during the fermentation of sik-hae. Summarizing the above results, the optimum fermentation period of sik-hae was concluded to be 15-days at all experimental temperatures except $5^{\circ}C$.

• The Korean Journal of Food And Nutrition
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• v.9 no.4
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• pp.385-391
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• 1996

To produce low salt fermented anchovy by an accelerated method with Asp. oryzae and Bacillus sp. koji and change of physicochemical properties in the fermentation during 60 days were examined. The contents of moisture, crude protein, ash and salinity of salted anchovy changed little during the fermentation with 62.5~63.8%, 12.0~14.1%, 12.8~13.8%, and 12.8~13.8%, respectively. but crude lipid decreased from 15.5~15.8% initially to 13.1~13.9% finally. The p during the fermentation decreased slowly until day 50 and increased afterwards. Acidity increased remarkably on day 10 and changed little afterwards. This increase in acidity was particularly observed in the use of Asp. oryzae koji. Amino nitrogen contents sharply increased until day 20 wit 686.0~756.0mg% and then increased slowly. Ammonia nitrogen contents in the use of koji increased until day 40 or 50 and decreased after that ; while those without koji steadily increased until day 60. The TBA values for all the samples reached the highest point on day from 20 to 30 and decreased afterwards. The TBA values and ammonia nitrogen contents were higher in Bacillus sp. koji than in Asp. oryzae koji. The alcohol contents of anchovy paste a little decreased during 10 days, increased slowly after that until day 50, and then decreased. The content of alcohol was higher in the use of koji than in the non koji.

• Korean Journal of Environmental Biology
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• v.24 no.2 s.62
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• pp.201-211
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• 2006

55 zooplankton taxa including 35 copepoda were observed in the Uldolmok waterway during the sampling period from August 2003 to April 2004. Neritic species showed the seasonal species fluctuation, and oceanic warm-water species occurred throughout the year. The number of taxa tended to increase at the flood tide from low tide to high tide, and to decrease at the ebb tide from high tide to low tide. Therefore, species composition of zooplankton in the Uldolmok waterway seemed to be affected by the inflow of oceanic waters with oceanic species all the year round. Total abundance of zooplankton ranged from 104 (February 2004) to 2,717 indiv. $m^{-3}$ (August 2003). According to the tidal cycle, the change of total abundance was more irregular and variable in November 2003 and February 2004 than August 2003 and April 2004. In August 2003 and April 2004, total abundance was low at the strong tide, and was high at low and high tide when tidal current was weak. Average abundances of dominant species such as Paracalanus indicus, Cirripedia nauplii and Acartia hongi were on the order of twice higher at ebb tide than flood tide. However, their abundances were also subject to wide fluctuation within flood tide and ebb tide. The changes of environmental parameters such as water temperature, salinity and chlorophyll-a concentration were negligible along the tidal periods in the Uldolmok waterway. Therefore, the advection, transfer and loss of zooplankton population derived from strong tidal current and eddy formed by the local difference of tidal velocity lead temporal variation of zooplankton community more complex and variable in the Uldolmok waterway.

• The Journal of Engineering Geology
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• v.14 no.3 s.40
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• pp.301-311
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• 2004

This study is suggested a new dielectric tracer test method to understand geological structure of porous media and groundwater flow to use the dielectric constant which is one of electrical special quality of various geological materials. To measure their parameters, tracer material is made an ethanol mixing liquid(EML) having a same specific gravity of water. Also, soil materials are prepared a dielectric tracer test using the FDR system that could measure dielectric constant for saturated standard sand and river sand layers which have different initial porosity. To compare with their results, we discussed with the concentration variation of saline water having a saline concentration $3\%$ which is general tracer material by using the electro multi-meter system in the laboratory or field test. In two tracer experiment results, EML tracer test could confirm definitely EML concentration variation from each saturated soil layer as standard and river sands. However, tracer test of saline water $3\%$ concentration could not confirm permeating movement of water by degree of salinity change because these are settled at lower part column in a whole column area continuously. These causes are that specific gravity of saline water is heavier than water. That is, it could know that deposition of saline water is composed of lower part of soil column continuously independently of the direction of water into saturated soil material.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.9
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• pp.995-1005
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• 2005

The study with laboratory sandbox model has been carried out to address potential use of reclaimed water, as a countermeasure artificially recharging the coastal aquifer, to effectively prevent from seawater intrusion due to overexploitation. It also investigated plausibility for either preserving or recovering the freshwater interface facing with seawater intrusion. To do this, we assessed hydraulic properties in artificial aquifer seawater/freshwater interface) depending upon the variation of extraction, storage and injection of reclaimed water. The variation of interface between freshwater and seawater were visualized by Surfer 8(Golden Software, USA) according to given experimental conditions. The interface between seawater and freshwater has been sensitively influenced by the change of extraction rate, where seawater zone migrated much faster into freshwater zone even though extraction rate became decreased. However, decreasing recharge rate could slow down moving of saline water zone toward freshwater zone. When the recharge was solely introduced into the sand box model, saline water intrusion was retarded than those of recharge and extraction working together. And also, the level of salinity of saline water was diluted by artificial recharge. It finally revealed that the artificial recharge would hydraulically avoid seawater intrusion while the freshwater sources could be conservatively utilized.

• Journal of Korean Society of Environmental Engineers
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• v.36 no.5
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• pp.303-310
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• 2014

This study investigated the reduction of food waste through the slurry phase decomposition in a source of food waste by microorganisms. The reactor used in the experiment was composed of both woodchip with wood material and sponges with polyurethane material as media of attached microorganisms, and food waste was mixed with a constant cycle consisted of a stirring device. During the experimental period of 100 days, the change in weight over the cumulative total amount of food waste added was reduced by 99%. Approximately, 1% of the residual food waste could be inherently recalcitrant materials (cellulose, hemicellulose, lignin, etc.) and thus was thought to be the result of the accumulation. The initial pH in wastewater generated from food waste was low with 3.3 and after 24 hours treatment this pH was increased to 5.8. The concentrations of COD, BOD, SS, salinity, TN and TP were gradually decreased. Food waste decay was proceeded by the seven species microorganisms identified and confirmed in this study, making a slurry phase and thus reducing residual food wastes. In the initial phase, the microbial population was approximately $3.3{\times}10^4$ cell/mL, and after 15 days this population was a constant with $5.1{\times}10^6$ cell/mL which means a certain stabilization for the reduction of food wastes. From these results, it can be considered that organic matter decomposition as well as the weight loss of food wastes by microorganisms is done at the same time.

• Journal of Korean Society of Environmental Engineers
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• v.39 no.4
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• pp.169-179
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• 2017

This study was conducted to supply information that can be utilized as data for desalination plant construction in the future by estimating unit cost of water production in the potential site of Incheon, Daesan, Yeosu, Busan, Ulsan and Sokcho in Korea. The production costs in Sokcho and Ulsan were similar to those of Busan and Yeosu. Those four sites showed better economic range due to low construction cost for intake facility compared to Incheon and Daesan. Although the salinity measured in the above 6 sites did not show perceptible effect on the production cost, the difference of seasonal seawater temperature needs to be considered due to the change of flux in reverse osmosis (RO) membrane. It turned out that the most critical parameters are the amortization in a year by the analysis of life cycle and the capacity of plant. Incheon and Daesan showed the difference of production cost up to 29% at the condition of amortization in 25 year, and up to 22% depending on plant capacity. However, the production cost in this study did not take into account of other indirect costs, therefore, this should be considered as the minimum cost.