• Korean Journal of Fisheries and Aquatic Sciences
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• v.31 no.6
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• pp.791-798
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• 1998

To develop natural flavoring substances. optimal hydrolysis conditions for two stage enzyme hydrolysates (TSEH) using low-utilized shellfishes such as purplish clam and frozen oyster stored at $-20^{\circ}C$ for 60 days. The optimal conditions for TSEH method were revealed in temperature at $50^{\circ}C$ 3 hours digestion with alcalase (Aroase AP-10, $0.3%$ w/v, pH 8.0) at the 1st stage and $45^{\circ}C$ 2 hours digestion with neutrase (Pandidase NP-2, $0.3\%$ w/v, pH 6.0) at the 2nd stage. Among water extracts, autolytic extracts and 4 kinds of enzyme hydrolysates tests, TSEH method was superior to other methods on the aspect of yields, nitrogen contents, taste such as umami and control of off-flayer formation, and transparency of extracts. From the results of chemical experiments and sensory evaluation, we may conclude that TSEH from low-utilized marine products is more flavorable compared the conventional enzyme hydrolysates, it could be commercialized as the seasoning substances.

• Journal of Korean Society of Environmental Engineers
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• v.29 no.4
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• pp.425-437
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• 2007

Flow distribution of water and sedimentation rate were investigated to understand the hydrodynamics and settling characteristics of particulate materials in a constructed wetland for treatment of non-point sources pollutants, the Sihwa constructed wetland, Korea. The Sihwa constructed wetland is divided into three sub-wetlands(the Banwol, the Donghwa and the Samhwa wetlands) to treat the polluted water from three streams, the Banwol stream, the Donghwa stream and the Samhwa stream. From the results of water flow experiment using dye(Rhodamine 50WT Red), it was found that the water flow in the wetland was prevailing at the waterway and open water. Dye was spread slowly in the closed water area planted by plants. The mean hydraulic retention time(HRT) at the upper area of high wetland and lower wetland of Banwol, was found to be 34.1 hr at the upper area and 74.6 hr at the lower area respectively, totaling approximately 108.7 hr(4.5 days). The sedimentation rate was higher at lower area(sites of B, C and D) of the wetland than upper area(site of A which is settling zone). Based on the forecast for 20 years as to the amount of sediment that can be deposited in the open water in the future, the sediment depth of each area would be like this: A: 6.3 cm, B: 8.3 cm, C: 7.0 cm, D: 9.5 cm. The contents of organic materials in the sediment deposited within the sediment trap were found to be higher overly in the first investigation period which had much rainfall, and B, C and D areas were found to have an increased COD accumulation than A area. Also, nitrogen and phosphorus were found to increase in the down-stream of the wetland. The results of this study suggest that a sustainable research and management for the characteristics of water flow pattern and sedimentation changeable as time passes is needs to maintain or improve the efficiency of water treatment in the constructed wetland.

• Korean Journal of Environmental Agriculture
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• v.21 no.3
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• pp.178-188
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• 2002

Constructed wetlands typically cost less to build and operate, and require less energy than standard mechanical treatment technology but they have similar performance to centralized wastewater treatment plants. Therefore, they were constructed especially many in rural areas, where are small villages but not industries. Plantless column tests were performed to investigate the possibility on using zeolite as a filter medium of constructed wetland for the wastewater treatment. Removal efficiency was $COD_{Cr}$ 94.63% T-P 41.41% and $NH_4^+-N$ 99.75% at hydraulic load 314 $L/m^2{\cdot}d$ and filtering height 100 cm filled with a zeolite mixture. This zeolite mixture consisted of 1 : 1 by volume of zeolites in the diameter range of 0.5 to 1 mm and 1 to 3 mm. Accordingly, hydraulic load 314 $L/m^2{\cdot}d$ was considered as optimal. Three zeolite mixtures were used to determine the optimal mixing ratio by volume of a zeolite (A) in the diameter range of 0.5 to 1 mm to a zeolite (B) in the diameter range of 1 to 3 mm 1 : 3, 1 : 1 and only B in A to B by volume were tested at hydraulic load 314 $L/m^2{\cdot}d$ and filtering height 100 cm $COD_{Cr}$ removal efficiency was more than 89% at mixing ratios of 1 : 3 and 1 : 1 in A to B. That of T-P ranged 56.42 to 58.72% and, that of T-N and $NH_4^+-N$ was 87% and 99% regardless of mixing ratios of two zeolites. Removal efficiency was lower at the column filled with only B. Removal efficiency was better at Inter medium filled with mixing ratio 1 : 1 in A to B than with the other mixing ratios. Thus, it was found that the mixture of mixing ratio 1 : 1 in A to B was appropriate far Inter medium of constructed wetland Removal efficiency was higher in down-flow than in up-flow, and all contaminants were removed most in 20 cm filter height near feeding area.

• Journal of Mushroom
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• v.18 no.1
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• pp.120-124
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• 2020

This study was conducted to provide basic data for setting a standard medium for winter mushroom cultivation. Investigation of medium composition in winter mushroom farms in Korea revealed that the types of medium used for each farm were slightly different and that the mixing ratio of the medium also varied. All farmers used corncob, rice bran, and beet pulp as the main media, and calcium carbonate and ground oyster shells were used at 1.0~3.8% to adjust the pH of the medium. Analysis of the physicochemical properties of the mixed media showed nitrogen content of 1.28~1.52%, carbon content of 45.7~48.5%, and C/N ratio of 30.7~37.9. The content of inorganic components was significantly different in each farm, depending on the type and amount of minerals in the mixed medium. Mycelial growth was the fastest at Farm 2, reaching 6.5 cm within 34 days of culture, followed by Farm 4 at 5.7 cm, whereas Farm 1, 3, and 5 showed similar growth. Mycelial density was high without any significant difference between farms. Survey of yield according to medium composition in each farm showed the highest yield in Farm 2 at 173.4 g/bottle, followed by Farm 1 at 168.4 g/bottle, whereas Farm 3 and 4 showed similar yield. However, Farm 4 had the lowest yield at 145.4 g/bottle. Therefore, mushroom yield was different depending on the medium composition in the farm, and thus selection of a medium that can be used universally in multiple mushroom farms was considered possible.

• Korean Journal of Food Science and Technology
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• v.42 no.4
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• pp.481-487
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• 2010

The nutritional components, antioxidant, and neuroprotective effects of water and a 50% methanol extract from litchi fruit pericarp were investigated. The most abundant mineral, amino acid, and fatty acid were K, proline, and palmitic acid, respectively. In addition, the total water phenolics and 50% methanol extracts were 8.02 and 12.28 mg/g, respectively. The DPPH, ABTS radical scavenging activities and ferric reducing antioxidant power of the water and 50% methanol extracts showed dose-dependent antioxidant activity. In a cell viability assay using MTT, almost all extracts showed a protective effect against $H_2O_2$-induced neurotoxicity, and lactate dehydrogenase leakage was also inhibited by the pericarp extracts. In particular, the 50% methanol extract showed a higher cell membrane protective effect than the water extract at the highest concentration. Consequently, these data suggest that litchi fruit pericarp can be utilized as an effective and safe functional food substances for natural antioxidants and may reduce the risk of neurodegenerative disorders.

• Journal of Life Science
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• v.25 no.12
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• pp.1408-1414
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• 2015

In this study, to retain a stable bacterial inoculant, Bacillus strains showing antifungal activity were screened. The improved production, antifungal mechanism, and stability of the antifungal metabolite by a selected strain, AF4, a potent antagonist against phytopathogenic Botrytis cinerea, were also investigated. The AF4 strain was isolated from rhizospheric soil of hot pepper and identified as Bacillus subtilis by phenotypic characters and 16S rRNA gene analysis. Strain AF4 did not produce antifungal activity in the absence of a nitrogen source and produced antifungal activity at a broad range of temperatures (25-40℃) and pH (7-10). Optimal carbon and nitrogen sources for the production of antifungal activity were glycerol and casein, respectively. Under improved conditions, the maximum antifungal activity was 140±3 AU/ml, which was higher than in the basal medium. Photomicrographs of strain AF4-treated B. cinerea showed morphological abnormalities of fungal mycelia, demonstrating the role of the antifungal metabolite. The B. subtilis AF4 culture exhibited broad antifungal activity against several phytopathogenic fungi. The antifungal activity was heat-, pH-, solvent-, and protease-stable, indicating its nonproteinous nature. These results suggest that B. subtilis AF4 is a potential candidate for the control of phytopathogenic fungi-derived plant diseases.

• Korean Journal of Food Science and Technology
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• v.36 no.6
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• pp.937-942
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• 2004

Physicochemical properties and mineral composition of seaweed salts prepared by incineration and osmotic dehydration methods were determined. As the incineration temperature increased, yield of seaweed salts, insoluble solids, pH, alkalinity, and oxidation-reduction potential (ORP) decreased. Alkalinity of salt prepared with sea tangle was higher than that of sea mustard. ORP decreased by incineration above $700^{\circ}C$, and was lower in salt with sea tangle. As incineration temperature increased, amounts of K and Ca in seaweed salt increased, whereas that of Mg decreased. Potassium and Ca contents of seaweed salt increased remarkably compared with those of common salt. Potassium content of sea tangle salt was higher than that of sea mustard. As incineration time increased, yield of seaweed salts, insoluble solid content, and pH decreased, whereas ORP of the salt increased. Potassium content of seaweed salt with incineration time, while Ca and Na contents decreased after incineration of 8 and 4 hr, respectively. Yield of seaweed salt by osmotic dehydration increased as immersion time in sea water increased. pH of salt from sea mustard was higher than that of sea tangle. ORP of seaweed salt dried three times was -128.8 mV, significantly lower than that of salt prepared by incineration method. As sea water immersion time increased, Mg content of seaweed salt increased significantly, while Ca content decreased. Potassium content of seaweed salt was higher in sea tangle salt. In case of salt prepared by incineration of residuals, pH increased with immersion time but ORP decreased.

• Korean Journal of Agricultural and Forest Meteorology
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• v.20 no.2
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• pp.149-158
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• 2018

Agriculture is strongly influenced by climate change such as increased temperature and carbon dioxide ($CO_2$). This study describes the effects of climate change elevated $CO_2$, temperature, and relative drought on growth responses and yield in potato (Solanum tuberosum L.). The assessment was conducted for spring seasons in Soil-Plant-Atmosphere Research (SPAR) chamber at National Institute of Crop Science (NICS). Potatoes exhibit a positive response to $CO_2$ enrichment but water stress primarily reduces potato canopy and tuber yield. Elevated $CO_2$ and temperature increased both dry weight and tuber yield. Elevated $CO_2$ and temperature influenced SPAR 2 plants to a larger, and tuber increased yield up to 28% of than in SPAR 1(30-year average temperature at 450 ppm of $CO_2$). Our study findings indicate that tuber yield increase in potato under high $CO_2$ concentration was due to an increase in the size of individual tubers rather than in the number of the tubers per plant. On other hand, SPAR 3(30-year average temperature $+2.8^{\circ}C$ at 700 ppm of $CO_2$ under water stress) was lower than SPAR 2(30-year average temperature $+2.8^{\circ}C$ at 700 ppm of $CO_2$) nearly 56% of tuber yield due to drought. The results confirm potato drought sensitivity in terms of yield response. The experiment also showed that, in the conditions of climate change, climate change scenarios that improve cropping systems with potato.

• Korean Journal of Soil Science and Fertilizer
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• v.33 no.6
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• pp.432-445
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• 2000

The objective of this study was to determine the effects of various kinds of composts on the change of nutrition loss in upland soils. Field experiments were conducted in the loam and sandy loam soils, while the clay loam and sandy loam soils were used for laboratory experiments. Various kinds of composts such as poultry manure compost(PMC), cow manure compost(CMC), human excrement sludge(HES), and food industrial sludge compost(FISC) were applied annually at rates of 0, 40, and $80mg\;ha^{-1}$ to soils grown with soybean and maize plants for 4 years during 1994 to 1997. The results of this study were as follows : The loss of nutrients in the form of cation and anion by run-off water increased with the increase of compost application rate. Compared with bare soils, maize cultivation decreased the nutrient loss by run-off from soils by 43% in anionic form and 32% in cationic form. Amount of cation loss were ordered $K^+$ > $Ca^{2+}$ > $Na^+$ > $Mg^{2+}$ > $NH_4{^+} $ and that of anion loss were ordered $SO_4{^{2-}}$ > $NO_3{^-}$ > $Cl^-$ > $PO_4{^{3-}}$. Nutrient loss of sand loam soil in the cation and anion by percolation water increased 1.7 times compared with loam soil. $NO_3{^-}-N$ contents in percolated water were high at the initial stage after compost application, and the amounts were higher in sandy loam soil than loam soil. The maize cultivation also decreased the $NO_3{^-}-N$ contents in percolated water by 82% in loam soil, and 58% in sand loam soil. Soil pH of composts determined by laboratory incubation test increased pH 6.1~6.8 application with poultry and cow manure compost but application with human excrement sludge decreased pH 4.5~4.7. Soil EC were increased initially composts application and decreased up to 2 weeks, thereafter kept a certain level. Nitrogen mineralization rates of composts determined by laboratory incubation test at $25^{\circ}C$ were 39~76% in sandy loam soil, and 16~48% in clay loam soil.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.4 no.1
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• pp.33-39
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• 1999

In order to understand the importance of tidal action and $NH_4{^+}$ -nitrification in the removal of dissolved oxygen (DO) and $NH_4{^+}$, concentrations of DO, $NH_4{^+}$, $NO_2{^-}$ and $NO_3{^-}$ were measured with time for water samples collected at different tidal state in the eutrophic macrotidal Han River estuary. Field measurements indicated that most environmental parameters, except for the water temperature and DO concentration, were tightly controlled by the eutrophic freshwater runoff and large-scale tidal action. Dark incubation of the water sample at $25^{\circ}C$ showed that the removal rates of DO and $NH_4{^+}$ in high tide sample were 2.76 ${\mu}M\;O_2\;d^{-1}$ and 1.76 ${\mu}M\;N\;d^{-1}$ respectively, and increased to 5.66 ${\mu}M\;O_2\;d^{-1}$ and 3.36 ${\mu}M\;N\;d^{-1}$ respectively, in low tide sample. These changes indicated that microbial degradation and uptake of organic matter and inorganic nutrients were more active during low tide. $NH_4{^+}$-nitrification responsible for total DO removal in low tide (23.81%) and $NH_4{^+}$ turnover rates due to $NH_4{^+}$-nitrification in low tide (0.18 $d^{-1}$) were approximately 3.7 times and 3 times, respectively, higher than those in high tide. These results indicated that $NH_4{^+}$ -nitrifying bacteria introduced into the Han River estuary during low tide played a significant role in the removal of DO and $NH_4{^+}$. The decreasing removal rates in DO and $NH_4{^+}$ with the increasing tidal level seemed to be associated with the salinity impact on the halophobic freshwater $NH_4{^+}$-nitrifying bacteria. The results implied that anthropogenic $NH_4{^+}$ sources should be treated prior to the freshwater runoff into the estuary for the effective control of $NH_4{^+}$ in the Han River estuary. These results also suggest that parallel ecological studies on the chemoautotrophic nitrifying bacteria are essential for the elucidation of nitrogen cycles in the eutrophic Han River estuary.