• Journal of Korea Water Resources Association
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• v.48 no.1
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• pp.45-55
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• 2015

In this study, when seawall or harbor gate is installed for coastal disaster prevention, a two-dimensional water analysis in the bay is carried out to consider the flood amount of river inflow and effect of harbor gate. The Yeongsan river and the port Mokpo area are selcected for the study region. Then, by analyzing the hydraulic characteristics of flood flow of the Yeongsan river, we analysed the compatibility of the results in the two-dimensional hydrodynamic model. A tw-odimensional water analysis were conducted for the four cases considering whether a harbor gate is installed or not, and whether the inland water boundary condition is considered or not, also with open sea boundary condition. The results of the two-dimensional water analysis shows that water level change near the port Mokpo area is mainly caused by the discharge of the estuary barrage of the Yeongsan river because the harbor gate was installed. In addition, it is revealed that the volume of reservoir created by the harbor gate and the estuary barrage is too much small compared to the volume of the discharge from the Yeongsan river. Therefore, when the harbor gate is installed in the open sea, we concluded that a flexible management between the harbor gate and the estuary barrage of the Yeongsan river is required. A initial water level of the bay and outflow from the harbor gate are proposed for disaster prevention in the coastal area of port Mokpo.

• Journal of the Korean Wood Science and Technology
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• v.16 no.4
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• pp.48-53
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• 1988

This study was carried out to investigate the effects of pressing time and spreading amount, moisture content, gap-distance with butt to butt joint and adhesives on bonding strength in manufacturing the laminated wood with Pitch pine (Pinus rigida). The results obtained were as follows: 1) The pressing time of 12 hours, 10 kilogram per square centimeter of pressure and 200 gram per square meter of spreading amount were required to reach over 50 kilogram per square centimeter (block shear strength) in manufacturing the laminated wood by aqueous vinyl urethane adhesive. 2) The bonding strength decreased with the increase of moisture content of wood. The block shear strength, however, showed over 100 kilogram per square centimeter when the strength test was carried out after air-drying the laminated wood in high moisture content (30-70%). 3) Regardless of direction of load, every flexural property decreased with the increase of gap-distance with butt to butt joint. However, little of every flexural property was changed at 0.5 millimeter of joint-gap distance. The flexural property of vertically laminated wood (perpendicular to glue line to load direction: 1) showed more than that of horizontally laminated wood (parallel to glue line to load direction: //). 4) Among five adhesives used at this experiment, the bonding strength of aqueous vinyl urethane adhesive was the highest in dry bond and wet tests.

• Korean Journal of Ichthyology
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• v.30 no.2
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• pp.84-91
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• 2018

The study about maturity and spawning of Korean Mandarin fish, Siniperca scherzeri collected using the set net and gill net in Soyangho Lake from April to November 2014 was conducted. The number of individuals was 401 (female: 204, male: 197). The total length of females ranged from 113 mm to 365 mm and that of males was from 140 mm to 342 mm. The water temperature in May which is the start of spawning season indicated about $15^{\circ}C$ and gradually increased to July ($26^{\circ}C$). Gonadosomatic index (GSI) of females indicated 2.3%, 4.6% and 3.1%, respectively, in May to July. Males' value showed the similar pattern recording 8.0%, 6.6% and 4.5% in the same time. According to histological observations of gonadal tissue, the most of female in May had the gonadal tissue of maturing and mature stage. And the ovary of June was mostly in the stage of ripe and spawning and a number of individuals in July was recovery stage. In the case of male, a number of males in May showed in the stage of mature. The testis of June showed that mature sperm was releasing. And the testis of July was mostly in recovery stage. The total length at 50% group maturity was estimated 245.16 mm. As shown in the above, the main spawning period of S. scherzeri was May to June.

• Journal of the Korean association of regional geographers
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• v.15 no.6
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• pp.720-735
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• 2009

This paper studies the characteristics of the restructuring of chemical industrial complex in JiLin city since 1978 focusing on enterprise organization, the process of production, labor, and consumer market. The number of chemical industrial enterprises and their partnership with subcontractors have increased since 2001. As for the type of cooperation group, research institutes and local government are accounted for the greatest portion. The chemical industrial enterprise in JiLin which has adopted Fordism production method still has the highest percentage in 2007. And in the shift process of production system after China's entry into WTO(in 2001), chemical industrial enterprise in JiLin city takes allowing more investment in production technologies as core strategy, while taking improvement in equipment and development of new products as core strategy in the shift process of production technology. The degree of labor re-education was highest in 2007, and as for the relationship between labor and management, enterprises which evaluate the ability of performance of duty are increasing. The characteristics of restructuring of chemical industrial complex on consumer market, domestic market accounted for the greatest portion, on the other side the export is feeble. As for strategy of market restructuring, industrial enterprise in JiLin city should use Quality improvement and high-value added as core strategies to cope with alteration of market.

• Journal of fish pathology
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• v.26 no.3
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• pp.303-310
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• 2013

Since March in 2013, Inland Aquaculture Research Center, NFRDI has cultivated 1,000 wild swamp eel(Monopterus albus) for species conservation research. While cultivating, 100 fishes showed clinical sign that darkness color, mucus hypersecretion and anus rubor. Even some of them were died. Result of anatomical test, all 100 fishes were infected with intestinal parasite, acanthocephalan. So we were going to determine the case of acanthocephalans infection in swamp eel(Monopterus albus) as histopathologically. Acanthocephalan was founded in alimentary canal only. Parasite were confirmed 19 unit in individual fish, averagely. Heavy infected fishes were confirmed enterocleisis by acanthocephalans. Worms were attachment in submucosa layer of alimentary canal by invading proboscis. Characteristic symptoms were observed in stomach and intestine, including hyperemia in mucous epithelium, infiltration of eosinophills in submucosa layer, inflammation, parasitic granuloma. Some fishes showed vacuolization of gastricgland epithelium, necrosis of intestinal mucosa. Other organs, excluding alimentary canal, were not found lesion. The results of this study, the effect of the acanthocephalan infection on swamp eel(Monopterus albus) could find and it seems to be a big help in the future swamp eel(Monopterus albus) cultivation.

• Journal of Wetlands Research
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• v.20 no.4
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• pp.322-329
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• 2018

In this study the community characteristics of benthic macroinvertebrates distributed in stream of Gaya Mountain were figured out and the correlation with the physicochemical water quality factors were calculated. During the study period, total 4 phyla, 6 classes, 13 orders, 36 families, 100 species of benthic macroinvertebrates were recorded. Ephemeroptera were the most dominant followed by Trichoptera, Plecoptera, Diptera, Non-insecta, Hemiptera, and Odonata. The overall dominant species was Cincticostella levanidovae by dominance rate in 17.72%, subdominant species was Hydatophylax nigrovittatus by dominance rate in 6.15%. The biotic indices showed the diversity index 5.17, richness index 12.44, dominant index 0.24 and evenness index 0.78, there is no absolutely dominant benthic macroinvertebrates in the stream of Gaya Mountain. We identified the correlation between the species number and individuals of main taxa and the physicochemical water quality factors. Ephemeroptera and Plecoptera showed a negative correlation with water temperature, but they represented a positive correlation with the dissolved oxygen. This results suggest that water temperature and dissolved oxygen are important physicochemical water quality factors affects the distribution of Ephemeroptera and Plecoptera, the indicators of clean water stream.

• Journal of Marine Life Science
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• v.7 no.2
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• pp.171-179
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• 2022

The present study investigated the survival rate, respiration rate, plasma stress index, and histological changes according to exposure time of cultured red seabream (Pagrus major) and olive flounder (Paralichthys olivaceus) exposed to Cochlodinium polykrikoides red tide. Fish cultured in natural seawater were used as the control group. Cochlodinium polykrikoides density was set to 5,500±200 cells·ml^-1 in the experimental groups. All red seabreams died within 1 hour of exposure to red tide, whereas all olive flounders died within 5 hours of exposure. Analysis of physiological response revealed that in red seabream, plasma glutamic oxaloacetic transaminase (GOT), glutamic pyruvic transaminase (GPT), catalase (CAT), and glutathione peroxidase (GPx) concentrations were increased; plasma glucose and superoxide dismutase (SOD) concentration were decreased. Meanwhile, in olive flounders, plasma cortisol, GOT, and GPT concentrations were increased; plasma glucose concentrations were increased during the first hour of exposure, followed by decrease after 5 hours; and plasma SOD, CAT, and GPx concentrations decreased during the first hour of exposure. Histological analysis revealed structural damage to the gills of both red seabream and olive flounder. In conclusion, the exposure of red seabream and olive flounder to Cochlodinium polykrikoides red tide at the density of 5,500 cells·ml^-1 induces oxidative stress, which activates antioxidant defense mechanisms, ultimately leading to liver and gill damage.

• Journal of Marine Life Science
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• v.7 no.1
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• pp.45-51
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• 2022

The profer salinity range for aquaculture of hybrid grouper (Epinephleus bruneus♀ × Epinephleus lanceolatus♂) were evaluated in terms of their survival, growth, feed intake and physiological responses after 30 days of exposure to different salinities (0 psu, 3 psu, 5 psu, 10 psu, 15 psu, 20 psu, 25 psu, 30 psu). Hybrid grouper all died at 0 psu salinity on the 4th day of exposure but all hybrid survived at a salinity of 5 psu or higher during the exposure period. Body length and weight increased above 5 psu salinity and the growth rate was the highest at 30 psu. Hybrid exposed to 3 psu did not eat the feed pellet. Feed intake did not show a significant difference between salinity 20 psu, 25 psu and 30 psu. Plasma osmolality of the juvenile hybrids exposed to different salinities was 341~368 mg Osmol/kg above 5 psu. The oxygen consumption rate was the highest at 30 psu with 163.6±22.3 mg O₂/kg fish/h. SOD, CAT and GSH-PX were significantly higher at 15 psu. Therefore, the critical salinity for survive of the juvenile hybrid was 5 psu, and the proper salinity for optimal culture was analyzed with 20~30 psu.

• Korean Journal of Environmental Biology
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• v.40 no.4
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• pp.641-650
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• 2022

The purpose of this study was to compare the efficiency of air and oxygen injected into the underwater non-thermal dielectric barrier discharge plasma (DBD plasma) device used to remove five types of antibiotics (tetracycline, doxycycline, oxytetracycline, clindamycin, and erythromycin) artificially contained in the fish farm discharge water. The voltage given to generate DBD plasma was 27.8 kV, and the measurement intervals were 0, 0.5, 1, 2, 4, 8, 16 and 32 minutes. Tetracycline antibiotics significantly decreased in 4 minutes when air was injected and were reduced in 30 seconds when oxygen was injected. After the introduction of air and oxygen at 32 minutes, 78.1% and 95.8% of tetracycline were removed, 77.1% and 96.3% of doxycycline were removed, and 77.1% and 95.5% of oxytetracycline were removed, respectively. In air and oxygen, 59.6% and 83.0% of clindamycin and 53.3% and 74.3% of erythromycin were removed, respectively. The two antibiotics showed lower removal efficiency than tetracyclines. In conclusion, fish farm discharge water contains five different types of antibiotics that can be reduced using underwater DBD plasma, and oxygen gas injection outperformed air in terms of removal efficiency.

• Journal of Marine Life Science
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• v.8 no.2
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• pp.128-135
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• 2023

The present study was tried to identify whether the eel's larva was close to a conger (Conger myriaster), a pipe conger (Muraenesox cinereus) or four species of Anguilla. Experimental fishes were collected by set net in the gulf of enggang, Namhae, Korea from May to June. Their morphological characteristics were compared with adult fishes of a conger, a pipe conger and four species of Anguilla. For genetic classification, DNA was isolated and amplified by using 12S rRNA and 16S rRNA primer set. The PCR products were direct sequencing in both directions. The nucleotide sequences were analyzed using softwares. As results of morphological measurement on eel's larva, the percentages of head length and preanal length against total length were similar with a conger. Based on the nucleotide sequences, the phylogenetic tree also revealed a close relationship to a conger. Therefore, eel's larva, caught in Namhae from May to June, was identified into a conger's larva.