• Korean Journal of Fisheries and Aquatic Sciences
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• v.18 no.5
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• pp.464-470
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• 1985

Some eels Anguilla japonica, ranging from 16 to 23 g in their weight(average: 20 g), were sampled at the private eel farming company equipped with water recycling system, located at Kimhae city, Kyungnam Province, Korea. Three kinds of vaccine were prepared with Vibrio anguillarum (EPM-8406) isolated at National Fisheries University in Korea for the immune response experiment against eels; those vaccines were made by inactivating the strain with $0.3\%$ formalin for 24 hrs at $25^{\circ}C$, heating for 3 mins or for 15 mins at $121^{\circ}C$, respectively. The various optimal vaccination conditions for the control of vibriosis in the fish were investigated based on the cultivation temperature, vaccination concentration and booster effect. The maximum titer rapidly increased with higher temperature up to $23^{\circ}C$, but there were little differences between $23^{\circ}C\;and\;28^{\circ}C$. The formalin-killed vaccine showed good efficacy at the injection concentration of above $10^8$ cells per fish and little effect at the below $10^7$ cells. The booster effect on the vaccination showed good efficacy above twice-injections with little difference between the numbers of injection.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.19 no.1
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• pp.10-19
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• 1986

A study on the rapid fermentation of fish sauce has been carried out for effective utilization of sardine. The frozen sardine was thawed at room temperature, chopped, homogenized with equal amount of water and then hydrolyzed by addition of commercial proteolytic enzymes such as bromelain, papaya protease, ficin and a enzyme mixture under different conditions of hydrolysis. The effect of wheat gluten for masking fishy odor and color development during thermal treatment were also tested. The reaction mixture was heated for 30 minutes at $100^{\circ}C$ for enzyme inactivation, pasteurization and color development and then centrifuged for 20 minutes at 4,000 rpm. Finally, table salt and benzoic acid were added for bacteriostatic effect. The results were summarized as follows ; 1. The hydrolyzing temperature, time, pH and the concentration of enzymes based on the weight of whole sardine for optimal hydrolysis were as follows: autolysis, $52.5^{\circ}C$, 4 hours, pH 8.0: with $0.25\%$ bromelain, $52.5^{\circ}C$, 4 hours, pH 6.6 :with $0.25\%$ ficin, $52.5^{\circ}C$, 4 hours, pH 6.8: with $0.3\%$ papaya protease, $52.5^{\circ}C$, 4 hours, pH 6.6: with $6\%$ enzyme mixture, $52.5^{\circ}C$, 4 hours, pH 6.9, respectively. But pH control was not much beneficial in increasing yield. 2. The hydrolytic reaction of chopped sardine with proteolytic enzymes could be interpreted as a first order reaction that devided into 2 periods with different reaction rate constsnts. $Q_{10}$ values of the first period prior to 4 hours were 1.23 to 1.31, and those of post 4 hours were 1.25 to 1.55. The corresponding activation energies were $1.81{\times}10^4\;to\;2.34{\times}10^4\;kJ/kmol$ and $1.92{\times}10^4\;to\;3.77{\times}10^4\;kJ/kmol$, respectively. 3. The reasonable amount of $75\%$ vital wheat gluten for addition was $9\%$ of chopped sardine. 4. The dark brown color was mainly developed during the thermal treatment for 30 minutes at $100^{\circ}C$ and not changed during storage.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.43 no.6
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• pp.648-653
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• 2010

This study was performed to investigate the inhibitory activity of Sargassum thunbergii (ST) against ${\alpha}$-amylase and elucidate the availability of ST extract as a functional food agent. To test the inhibitory activity of ST against ${\alpha}$-amylase, porcine pancreatic ${\alpha}$-amylase and potato starch were used as substrates. It was revealed that ST crude ethanol extracts have high ${\alpha}$-amylase inhibitory activity. Subsequently, ST crude ethanol extract was separated into five partition layers by solvent extraction: n-hexane, chloroform, ethyl acetate, butanol, and water. Chloroform and n-hexane fractions showed higher inhibitory activities than did acarbose (positive control). To confirm the changes in enzyme inhibitory activity by physical treatments, ST crude ethanol extract was subjected to heat, pH, and ${\gamma}$-irradiation treatments. In all heat treatments with the exception of one ($121^{\circ}C$, 15 min), the inhibitory activity was increased compared with the untreated group. With regard to pH stability, ST extract showed no significant changes at pH 4.6, but somewhat decreased inhibitory activity was revealed at pH 2, 8, and 10. On the other hand, ST ethanol extract was stable under ${\gamma}$-irradiation under all conditions (3.20 kGy). In summary, ST ethanol extract can be used in the food industry as a natural ${\alpha}$-amylase inhibitor.

• Journal of the Korean Electrochemical Society
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• v.12 no.2
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• pp.148-154
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• 2009

With respect to the durability of large scale ($150cm^2$) membrane electrode assembly (MEA) of direct methanol fuel cell (DMFC), degradation phenomena at cathode is monitored and analyzed according to the position on the cathode surface. After constant current mode operation of large scale MEA for 500 hr, the MEA is divided into three parts along the cathode channel; (close to) inlet, middle, and (close to) outlet. The performance of each MEA is tested and it is revealed that the MEA from the cathode outlet of large MEA shows the worst performance. This is due to the catalyst degradation and GDL delamination caused by flooding at cathode outlet of large MEA during the 500 hr operation. Particularly on the catalyst degradation, the loss of electrochemically active surface area (ECSA) of catalyst gets worse along the cathode channel from inlet to outlet, of which the reason is believed to be loss of catalysts by dissolution and migration rather than their agglomeration. The extent of loss in the performance and catalyst degradation has strong relation to the cathode flooding and it is required to develop proper water management techniques and separator channel design to control the flooding.

• Journal of Microbiology and Biotechnology
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• v.27 no.11
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• pp.2044-2051
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• 2017

The main pathological hallmark of Alzheimer's disease is the deposition of amyloid-beta ($A{\beta}$) peptides in the brain. $A{\beta}$ has been widely used to mimic several aspects of Alzheimer's disease. However, several characteristics of amyloid-induced Alzheimer's disease pathology are not well established, especially in mice. The present study aimed to develop a new Alzheimer's disease model by investigating how $A{\beta}$ can be effectively aggregated using prokaryotes and eukaryotes. To express the $A{\beta}42$ complex in HEK293 cells, we cloned the $A{\beta}42$ region in a tandem repeat and incorporated the resulting construct into a eukaryotic expression vector. Following transfection into HEK293 cells via lipofection, cell viability assay and western blotting analysis revealed that exogenous $A{\beta}42$ can induce cell death and apoptosis. In addition, recombinant His-tagged $A{\beta}42$ was successfully expressed in Escherichia coli BL21 (DE3) and not only readily formed $A{\beta}$ complexes, but also inhibited the proliferation of SH-SY5Y cells and E. coli. For in vivo testing, recombinant His-tagged $A{\beta}42$ solution ($3{\mu}g/{\mu}l$ in $1{\times}PBS$ containing $1mM\;Ni^{2+}$) was injected stereotaxically into the left and right lateral ventricles of the brains of C57BL/6J mice (n = 8). Control mice were injected with $1{\times}PBS$ containing $1mM\;Ni^{2+}$ following the same procedure. Ten days after the sample injection, the Morris water maze test confirmed that exogenous $A{\beta}$ caused an increase in memory loss. These findings demonstrated that $Ni^{2+}$ is capable of complexing the 50-kDa amyloid and that intracerebroventricular injection of $A{\beta}42$ can lead to cognitive impairment, thereby providing improved Alzheimer's disease models.

• Journal of the Korean Society for Marine Environment & Energy
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• v.14 no.2
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• pp.130-137
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• 2011

To improve sediment quality in eutrophic coastal areas using benthic microalgae, we examined the effects of temperature and salinity on the growth of benthic microalgae Achnanthes sp., Amphora sp., Navicula sp. and Nitzschia sp. isolated from Sujeong Bay, Korea, using batch cultures. The maximum growth rates were obtained under the combined temperature and salinity conditions of $25^{\circ}C$ and 25 psu for Achnanthes sp. (0.60 /day), $15^{\circ}C$ and 25 psu for Amphora sp. (0.56 /day), $20^{\circ}C$ and 30 psu for Navicula sp. (0.53 /day), $20^{\circ}C$ and 25 psu for Nitzschia sp. (0.48 /day). Considering these results of temperature and salinity conditions required for optimum growth (${\geq}$ 70% of maximum specific growth rate), Amphora sp. Navicula sp. and Nitzschia sp. were characterized as eurythermal and euryhaline species, while Achnanthes sp., which exhibited extremely low survival at low temperature. In conclusion, Amphora sp., Navicula sp. and Nitzschia sp. may be useful species for phytoremediation, to control eutrophication and hypoxic water and thus improve environmental conditions of polluted coastal areas.

• Journal of the Korean Regional Science Association
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• v.34 no.1
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• pp.19-30
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• 2018

Social overhead capital(SOC) is an essential element for society to be developed and operated normally. In spite of the increase in the importance of SOC, It is difficult to present the criteria for the appropriate investment of SOC. and The discussion on making SOC investments of local government is insufficient. If the local autonomy has been guaranteed, local government increases investment in regional public goods that residents prefer. Reflection of such residents preferences is the driving force to bring the efficiency of resource allocation in the decentralization theorem. In this study, the authority and autonomy of local governments are measured through local finance. and the decision-making of local governments for SOC investment is examined in point of decentralization theorem. In the empirical analysis, the elasticities of fiscal resources are estimated for facilities(road, water and sewage, irrigation canal and flood control) that local governments are involved in investment. These decisions made by metropolitan cities and provinces were different. The difference was most evident in the effect of per capita local tax on investment. These results show that metropolitan cities and provinces that have different situation made investment decisions differently. It shows that local governments reflect the preferences of the residents in making an investment. The main implication of this study is as follow. In case the role of local government in social overhead capital investment is increased, the increase in efficiency of resource allocation occurs. and The fiscal resources must be raised by local taxes rather than the financial resources from the central government.

• The Korean Journal of Pesticide Science
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• v.15 no.3
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• pp.278-288
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• 2011

This study was conducted to evaluate the safety of ${\beta}$-carotene biofortified rice, a genetically modified organism (GMO) developed by Rural Development Administration. ${\beta}$-carotene biofortified rice were exposed on Sprague-Dawley rats for 13 weeks. All rats survived until the end of the exposure period. There were no biologically significant differences in body weight, feed and water consumption, weight gains and feed efficiency. There were no clinical signs of toxicity attributable to exposure to GM rice. Mild decreases in AST, ALT, TG levels were observed in Group II (25% GM rice (w/w) and Group III (50% GM rice (w/w), both in females and males. Results of histopathological changes treated with the ${\beta}$-carotene biofortified rice had no significant differences between the control and treatment groups. Based on these results, we deemed that genetically modified ${\beta}$-carotene biofortified rice was as safe as conventional rice.

• Tunnel and Underground Space
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• v.25 no.2
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• pp.155-167
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• 2015

The thermal-hydrological-mechanical (T-H-M) behavior of rock mass surrounding a high-temperature cavern thermal energy storage (CTES) operated for a period of 30 years has been investigated by TOUGH2-FLAC3D simulator. As a fundamental study for the development of prediction and control technologies for the environmental change and rock mass behavior associated with CTES, the key concerns were focused on the hydrological-thermal multiphase flow and the consequential mechanical behavior of the surrounding rock mass, where the insulator performance was not taken into account. In the present study, we considered a large-scale cylindrical cavern at shallow depth storing thermal energy of $350^{\circ}C$. The numerical results showed that the dominant heat transfer mechanism was the conduction in rock mass, and the mechanical behavior of rock mass was influenced by thermal factor (heat) more than hydrological factor (pressure). The effective stress redistribution, displacement and surface uplift caused by heating of rock and boiling of ground-water were discussed, and the potential of shear failure was quantitatively examined. Thermal expansion of rock mass led to the ground-surface uplift on the order of a few centimeters and the development of tensile stress above the storage cavern, increasing the potential of shear failure.

• Korean Journal of Environmental Biology
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• v.25 no.3
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• pp.223-227
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• 2007

Crop loss and damage by wildlife are becoming more serious to residents inside and around National Parks of Korea annually. It could be caused by small size of Parks, which is couples of ten $km^2$ only, and more than a third of total parks' areas are belonging to privates. Wild boar (Sus scrofa) is one of the most harmful pests in nationwide. Treading down crop field using as bedding or resting site are major damaged types and foraging behavior is following. Besides of boars, Korean water deer (Hydropotes inermis), racoon dog (Nyctereutes procyonoides), and badger (Meles meles) are another serious pests. Mainly, farm products planted in upland, such as corns, sweet potatoes, cabbages, etc. are harmed easily, a rate reaches up to 76.9% of whole losses. 92.4% (n=187) of interviewees, who are mostly seniors, cultivate small crop fields smaller than 1 ha. Crop damage would be started from June to late November, time differences are happened due to latitude, climate condition, and crop differences of National Parks. Dusting animal repellents are easier and widespread methods to prevent animal foraging to crop fields and installing noisy makers using gun powder and setting up scarecrows are traditional methods for repelling animals. Nevertheless, effects of these self-defence are turned out to be useful soon after labors done only. Since legal compensation for crop damages by wildlife are not prepared systematically so far, crop loss are rarely reported to local government by most farmers. Systematic and objective methods for quantifying of crop loss by wildlife and population managements system should be offered urgently to well-managed animals habitat and residents' living inside National Parks.