• Journal of Ecology and Environment
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• v.40 no.1
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• pp.24-33
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• 2016

Background: Previous numerous studies on watershed scale demonstrated that the constructions of upper dams may influence the below dams due to modifications of flow regime and nutrient inputs. Little is known about how the dam constructions influence the downstream lakes or reservoirs in the regional scale. This study demonstrates how the construction of upper dam (i.e., Yongdam Dam) influences nutrient regime, trophic relations, and empirical models in Daechung Reservoir (DR). Yongdam Dam was constructed at the upstream region of DR in year 2000. Results: The analysis of hydrological variables showed that inflow and discharge in the DR were largely reduced after the year 2000. The construction of upper dam construction also resulted in increases of water temperature, pH and conductivity (as an indicator of ionic content) in the DR. Empirical models of TP-CHL and N:P ratio-CHL suggested that stronger responses of CHL to the phosphorus were evident after the upper dam construction, indicating that algal production at a unit phosphorus increased after the upper dam construction. Mann-Kendall tests on the relations of N:P ratios to TN showed weak or no relations ($t_{au}=-0.143$, z = -0.371, p = 0.7105) before the dam construction, while the relation of N:P ratios to TP showed strong in the periods of before- ($t_{au}=-0714$, z = -2.351, p = 0.0187) and after the construction ($t_{au}=-0.868$, z = -4.270, p = 0.0000). This outcome indicates that TP is key determinant on N:P ratios in the reservoir. Scatter Plots on Trophic State Index Deviations (TSIDs) of "TSI(SD) - TSI(CHL)" against "TSI(TP) - TSI(CHL)" showed that the dominance of clay turbidity or light limitation was evident before the upper dam construction [TSI(TP) - TSI(CHL) > 0 and TSI(SD) - TSI(CHL) > 0] and phosphorus limitation became stronger after the dam construction [(TSI(TP) - TSI(CHL) < 0 and TSI(SD) - TSI(CHL) > 0]. Conclusions: Overall, our analysis suggests that the upper dam construction modified the response of trophic components (phytoplankton) to the nutrients or nutrient ratios through the alteration of flow regime, resulting in modifications of ecological functions and trophic relations in the low trophic levels.

• The Korean Journal of Pesticide Science
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• v.18 no.4
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• pp.376-382
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• 2014

The soluble loess-sulfur mixture allowed standing to remove insoluble component materials for five weeks after manufacturing. We decreased the pH level of soluble loess-sulfur mixture at pH 1.0 modified with decreasing 25% sodium hydroxide than original content. The pH ranges of soluble loess-sulfur mixture solutions were adjusted to pH 5.0-pH 11.0 (pH 1 unit) with brown rice vinegar (pH 2.8). The pH of original loess-sulfur mixture was about pH 13 and damaged the foliar parts and young leaves of tomato after twice application. These stock solutions can be diluted 500:1 with tap water to make a 0.05% working solution and were sprayed two times with 7 days interval to the leaf and stem of tomato, which were spontaneously infected with E. cichoracearum. Control efficacy of powdery mildew ranged from 85% to 90% at 7 days after first application. After second application, each loess-sulfur mixture solutions adjusted pH level significantly suppressed the powdery mildew disease in tomato. Consequently, loess-sulfur complex adjusted pH level with brown rice vinegar was suggested to be low in acute toxicity at all different pH values and suggested to use an agent for control of tomato powdery mildew in organic farming.

• Journal of the Korea Organic Resources Recycling Association
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• v.11 no.3
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• pp.35-41
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• 2003

The on-site sewage sludge vermicomposting equipment was designed and evaluated on the batch and continuous tests. The vermicomposting equipment was designed to consider the mechanization as well as automation. Especially, the automatic controls of water content and temperature and the mechanization of the sludge feeding and cast separating were the important factors. In terms of changes in chemical characteristics when the equipments for experiments are operated continuously, the ORP, EC, $NH_3-N$ and $NO_3-N$ were found to be higher before and after treatment. In addition, it was found that changes in properties were low. Furthermore, the $NO_3-N$ concentration of the humus produced after treatment was found to be higher than the $NH_3-N$ concentration showing that it was appropriate based on the recycling criteria.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.24-24
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• 2017

Heavy metals at toxic levels have the capability to interact with several vital cellular biomolecules such as nuclear proteins and DNA, leading to oxidative stress in plants. The present study was performed to explore the metal tolerance mechanism in Sorghum seedling. Morpho-physiological and metal ions uptake changes were observed prominently in the seedlings when the plants were subjected to different concentrations of $CuSO_4$ and $CdCl_2$. The observed morphological changes revealed that the plants treated with Cu and Cd displayed dramatically altered shoot lengths, fresh weights, and relative water content. In addition, the concentration of Cu and Cd was markedly increased by treatment with Cu and Cd, and the amount of interacting ions taken up by the shoots and roots was significantly and directly correlated with the applied level of Cu and Cd. Using the 2-DE method, a total of 24 and 21 differentially expressed protein spots from sorghum leaves and roots respectively, 33 protein spots from sorghum leaves under Cd stress were analyzed using MALDI-TOF/TOF MS. However, the over-expression of GAPDH plays a significant role in assisting Sorghum bicolor to attenuate the adverse effects of oxidative stress caused by Cu, and the proteins involved in resistance to stress helped the sorghum plants to tolerate high levels of Cu. Significant changes were absorbed in the levels of proteins known to be involved in carbohydrate metabolism, transcriptional regulation, translation and stress responses. In addition, the up-regulation of glutathione S-transferase and cytochrome P450 may play a significant role in Cd-related toxicity and stress responses. The results obtained from the present study may provide insights into the tolerance mechanism of seedling leaves and roots in Sorghum under heavy metal stress.

• The Journal of Engineering Geology
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• v.20 no.1
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• pp.35-45
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• 2010

The soil tests have been performed on the specimens obtained from about 1,150 sites including landslides and non-landslides areas in natural terrains for last 10 years. Based on the results of those tests, the average soil properties are estimated and the simple equations for estimating permeability are proposed according to geologic conditions. The average permeability in Granite and Mudstone sites is higher than other sites and the content of silt and clay in Mudstone and Gneiss sites is higher than other sites. The correlation analysis and the regression analysis were performed to estimate the coefficient of permeability according to geological conditions. As the result of the correlation analysis, the coefficient of permeability is selected as a dependent variable, and the silt and clay contents, the water contents and the dry unit weights are selected as independent variables. As the result of the regression analysis, the silt and clay contents and the void ratio were involved commonly in the linear regression equations according to geological conditions. To verify the proposed the linear regression equations, the measured result of the coefficient of permeability at other sites was compared with the result predicted with the proposed equations. As the result of comparison, there were a little bit different between them for some data. However the difference was relatively small. Therefore, the linear regression equations for estimating the coefficient of permeability according to geological conditions may be applied to Korean soils. However, these equations should be verified and corrected continuously to improve the accuracy.

• Korean journal of food and cookery science
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• v.3 no.1
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• pp.31-36
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• 1987

The purpose of this study is to investigate the physicochemcal Properties of the cowpea crude and refined starch and to present the basic data for physicochemical factor which gives the properties of Mook to cowpea starch gel. Water binding capacity of crude starch was 235. In and that of refined starch was 186.0%. The pattern of change in swelling power and solubility for increasing temperature started to increase at $60^{\circ}C$ and increased rapidly from $70^{\circ}C$, for both of crude and refined starch. The optical transmittance of 0.2% crude and refined starch suspensions were increased from $65^{\circ}C$ and showed rapid increasement during 68~$80^{\circ}C$, and their curves showed two-stage processes. The gelatinization pattern for 6n crude and refined starch suspensions were investigated by the Brabender amylograph. The corves showed the pasting temperature of $72.0^{\circ}C$ and $72.1^{\circ}C$, peak height of 11303.U. ($88.0^{\circ}C$) and 970 B.U. ($83.5^{\circ}C$) for crude and refined starch, respectively, and both showed high viscosities when cooling. Blue values for crude and refined starch were 0.369 and 0.376 respectively. Alkali number of crude and refined starch were 7.77 and 7.34, and reducing values were 3.60 and 2. 10, respectively. Amylose content of cowpea starch was 33.7%. Periodate oxidation of the starch fractions resulted that amylose had the average molecular weight of 23590, degree of polymerization of 146 and amylopectin had the degree of branching of 3.42, glucose unit per segment of 29.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.4
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• pp.596-605
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• 2016

In previous years, practice hand grenades were composed of non-degradable plastics and caused environmental pollution. Therefore, this study applied PLA(Polylactic acid) to practice hand grenades that would biodegradable within a short time. High expectations are being placed on PLA as a substitute for plastics because it can decompose to water and carbon dioxide. The aim of this study was to confirm that the PLA material of a practice hand grenade has biodegradability in a pilot-scale composting unit and estimate the applicability for other items. A composting test was progressed according to ISO 16929(2013). The test process was found to be valid. At the end of the composting test (after 12 weeks), the entire content of the test bin with the test sheet was sieved, sorted and analyzed. A disintegration percentage of 99.2% was obtained after 12 weeks of composting. Therefore, the 90% pass level required by ISO 17088(2013), EN 13432(2000), and ASTM D 6400-12 was easily reached. On the other hand, more research will be needed to determine additional applications of PLA material for consumables.

• Korean Journal of Food Science and Technology
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• v.3 no.3
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• pp.172-177
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• 1971

The amount of the milk clotting enzyme which is produced by Dothiorella ribis in wheat bran was 950 Soxhlet units per gram of wheat bran. The milk clotting activity of this enzyme was increased by the elevation of clotting temperature and by the increase of the addition of $CaCl_2$ to milk. It was also increased when the pH of milk was lower than that of the fresh milk. When milk was diluted by distilled water, the milk clotting activity of the enzyme was decreased. And its milk clotting activity was good when milk was pasteurized at low temperature. The enzyme of Dothiorella ribis has larger proteolytic activity per Soxhlet unit than that of the milk clotting enzyme of Mucor pusillus Lindt. This enzyme was rather stable between pH 6 and pH 8 when it was conditioned for ten minutes. The heat stability of enzyme was tested by treating it under the condition for $10{\sim}60$ minutes. And the enzyme was stable under the temperature of $45^{\circ}C$. Also the recovery of protein as a form of curd was 76.2 percent to the total protein content of milk.

• Journal of the Korean GEO-environmental Society
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• v.10 no.6
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• pp.19-25
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• 2009

The current study developed light-weighted mixed soil that can solve problems related with soft soil such as ground subsidence, sliding and lateral displacement of ground. By reducing weight of reclaimed soil through mixing phosphogypsum and recycled EPS beads with the weathered granite soil. A series of geotechnical laboratory tests including physical index test, compaction test, CBR test, and direct shear test were performed and engineering properties were reviewed in order to assess applicability of the light-weighted mixed soil for roads and abutment and various back-filling materials at the reclamation area. Based on the laboratory test results, it was found that the maximum dry unit weight of the light-weighted soil ranges $14.32{\sim}15.79kN/m^3$ and the optimum water content ranges 21.91~24.23%, which means there is 11~19.3% weight decrease effect when comparing with general weathered granite soil. Also it was found that the corrected CBR value ranges 10.4~18.4% satisfying the domestic regulations on road subgrade and back-filling material. In addition, as for shear strength parameter, cohesion ranges 10.79~18.64 kPa and internal frictional angle ranges $35.4{\sim}37.2^{\circ}$, which are similar with those of general construction soil and back-filling material used in Korea. So it can be concluded that light-weighted mixed soil with phosphogypsum can be used effectively for soft reclamation ground as actual filling material and back-filling material. From the current study, it was found that light-weighted mixed soil with phosphogypsum has not only weight reduction effect, but also has no special problems in shear strength and bearing capacity. Therefore, it is expected that phosphogypsum can be recycled in bulk as road subgrade and back-filling material at the reclamation area.

• Korean Journal of Food Science and Technology
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• v.36 no.5
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• pp.754-760
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• 2004

Physicochemical properties and suitability of domestic wheat varieties for production of sugar-snap cookie were examined. Four kinds of commercially available wheat flour and six kinds of other domestic wheat varieties were tested. Domestic wheat varieties had protein contents ranging 7.7 to 11.5%, alkaline water retention capacity (AWRC) of 54.6 to 65.2%, Pelshenke values of 17 to 31 min, and sedimentation values of 19.6 to 30.8 mL. Peak viscosity range of Korean wheat flours measured by Rapid Visco Analyser was from 134.4 to 346.3 unit. Diameter of cookies fer US soft wheat flour was 7.8 cm and domestic wheat flours ranged from 7.2 to 7.9 cm. Cookie spread factors for Alchanmil, Tapdongmil, and Woorimil flours were higher than those of other flours. Protein content had significantly high correlation coefficient of $r=0.892^{**}$ with sedimentation value, and showed negative correlation with cookie diameter, spread factor, and top grain score. AWRC values had significantly high correlation coefficient of $r=-0.736^{**}$ with cookie diameter. Spread factor of cookie showed positive correlation with top grain score.