• Korean Journal of Environment and Ecology
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• v.34 no.4
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• pp.282-293
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• 2020

This study investigated a long-term variation trend of water quality, fish compositions, and ecological health conditions in the Gwanpyeong stream located in the nearby Daejeon metropolitan city to understand the impact of urban development projects on the aquatic ecosystem. The sampling was made in four surveys (2009, 2010, 2016, 2019) before and after urbanization. The urban development was conducted in 2008, resulting in the stream's ecological disturbance, and the stream restoration was conducted in 2012. Thus, stream monitoring was conducted to analyze the ecological trends before and after the restoration. The multi-metric models for Fish Assessment Index(FAI) and necropsy-based Health Assessment Index(HAI) were applied in the fish community and organ-level, respectively, to assess the ecological health of the stream. Minimum turbidity and chlorophyll-a(Chl-a) occurred in the mid-stream(St. 2), and this was probably due to rapid current velocity in the riffle zone. We collected 18 fish species, and the dominant species was Zacco platypus (40.6%). In 2016 immediately after the stream restoration, the relative proportions of sensitive species and insectivore species were the highest along with highest values in the species diversity and species richness index, resulting in the best condition in the ecological health, based on FAI model values. However, the ecological health, based on the FAI, became worse in the latest survey conducted in 2019. The analysis of the HAI model based on the organ-level approach showed skin erosion in the fish of upper stream, kidney defects in downstream, and the liver and gill defects observed in all sites, indicating that the anatomical health was also affected.

• Journal of Dairy Science and Biotechnology
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• v.35 no.1
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• pp.39-45
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• 2017

The market for lactose-hydrolyzed milk is growing due to an increased awareness of lactose intolerance, and increased market interest for modified milk with health claims. The aim of this study was to compare the quality characteristics of 2% lactose-hydrolyzed milk with its lactose hydrolysis rate, with the goal of applying the method to dairy product monitoring in the future. We observed that the freezing point of milk significantly decreased with increasing lactose hydrolysis rate. A linear relationship was found between lactose concentration and freezing point, following the equation (y=-50.416x + 767.91). However, no significant changes were observed in other physicochemical properties of the milk (pH, titratable acidity, total solids and color) (p<0.05). In conclusion, we could predict the residual lactose content quickly and easily in 2% low fat milk by measuring its freezing point. This could represent an easy means for assessing the lactose hydrolysis rate of dairy products.

• Journal of Korean Society of Forest Science
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• v.97 no.6
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• pp.589-596
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• 2008

This study was carried out in order to estimate site indices in un-stocked land by the physico-chemical properties of forest soil and to investigate the distribution of the physico-chemical properties by soil horizons. In Larix leptolepis Gordon stand, 80 sites were selected respectively to A and B horizon in soil. About the analysis method of data there was used stepwise regression analysis. Soil pH and T.N. of the physico-chemical properties turned out to be positively related to the site index. However, O.M. and Avail. $P_2O_5$ in soil were found out negatively related. In the degree of contribution of the variables to site index by each one of the stands, the highly effective variables were Base Sat., C.E.C., Sand, Exch. $Ca^{{+}{+}}$, and Exch. $Mg^{{+}{+}}$ in A horizon, Exch. $Ca^{{+}{+}}$, Base Sat., T.N., Avail. $P_2O_5$, and Clay in B horizon, and Exch. $Ca^{{+}{+}}$ and Base Sat. in both of A and B horizon. In conclusion, these results will provide not only the important criteria for establishment of management forest plan in un-stocked land but also the useful guidance for selecting the suitable sites and trees.

• Korean Journal of Food Science and Technology
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• v.34 no.2
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• pp.225-231
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• 2002

The physicochemical characteristics of pine nuts gruel were investigated to find the effects of processing condition during the processing. Three-dimensional response surface methodology was applied to investigate effects of ratio of water volume and pine nuts weight to rice weight and heating time on dependent variables of the physicochemical characteristics. The dependent variables in physicochemical characteristics were viscosity (cP), spreadability (cm), pH, soluble solid content (%), color, total sugar (%) and amylose content (%). The F-value of ratio of water volume and pine nuts weight to rice weight and heating time to viscosity were 8.91, 4.54 and 5.02 respectively and they are significantly different at 5% level. The F-value to spreadability were 5.44, 7.88 and 8.04 respectively and they are significantly different at 5% level. These results suggest that water volume, pine nuts weight and heating time greatly affect the viscosity and spreadability of pine nuts gruel. The processing condition also affect the soluble solid content. The changes of the processing condition did not affect the pH of pine nuts gruel. We found that the L, a, b value were affected more by ratio of water volume and pine nuts weight to rice weight than by heating time. The water volume affected more the total sugar and amylose content of pine nuts gruel than pine nuts weight and heating time.

• Food Science and Preservation
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• v.14 no.3
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• pp.269-275
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• 2007

This paper was study to develop an extract of Elaeagnus multiflora as a beverage component, and was part of a broader research project for at the development of processed foods using extract of Elaeagnus multiflora. Acceptable mixing properties of the beverage were significantly related to brix values, pH, total acidity, and total phenol contents. When brown rice vinegar was used as a supplement, the vinegar contributed only 1% of total acidity content, and the brix was below 5% of acceptable level. Maximal total acidity of the mixed beverage was attained which added 19.2%(v/v) of Elaeagnus multiflora extract and 7.6%(v/v) of brown rice vinegar. The mixed beverage contributed 0.88% of the total acidity content. The maximum condition of brix(11.5) of the mixed beverage was arrived to 24.7%(v/v) of Elaeagnus multiflora extract and 4.9%(v/v) of brown rice vinegar. The maximum polyphenol contents of beverage(14.47 mg%) was achieved which added 25.0%(v/v) of Elaeagnus multiflora extract and 4.3%(v/v) of brown rice vinegar.

• Journal of agriculture & life science
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• v.44 no.5
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• pp.81-90
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• 2010

This study was conducted to evaluate quality characteristics of citron from Namhae. The physicochemical properties, organic acid, free sugar and aroma components were analyzed and compared with citron harvested in different areas of Namhae (Seolcheon, Changseon and Idong-meyon). Total weight of citron was range of 120.51~176.56 g, total and peel weight of citron cultivated from Changseon were significantly higher than the other citron. The color of peel was not significant in cultivated area. Soluble solids was higher in citron from Changseon and Idong than Seolcheon. Total phenol and flavonoids contents in citron from Idong were higher than the others. Organic acids such as citric acid and malic acid were higher in citron from Changseon. The contents of fructose and glucose in peel and sucrose in pulp were detected higher amount. Major component of aroma profiles in citron from different region of was dl-limonene. It was amount to 57.60% in citron from Idong, 71.02% and 73.04% in citron from Seolcheon and Changseon of all aromatic components. These results were suggested that physicochemical properties and aroma components of citron have some difference by cultivation habit, period, different cultivar and producing areas.

• Korean Journal Plant Pathology
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• v.12 no.3
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• pp.336-344
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• 1996

생강뿌리썩음병은 충남 서산, 태안지역이 전북지역보다 3배나 심하게 발생하여 평균 발병주율이 18.1%에 달하였다. 이 병은 서산, 태안지역에서 7월 초순부터 발생하기 시작하여 한여름철의 기온이 높고 비가 많이 오는 장마가 7,8월에 급격히 증가하였으며 기온이 서늘해지기 시작하는 9월 중순까지 진전하였다. 서산, 태안지역과 완주지역은 토양의 이화학적성상 및 미생물상에 큰 차이를 보였으며 완주지역 토성은 서산, 태안에 비해 모래성분이 많고 pH가 낮으며, 유기물, 인산, 치환성 양이온의 함량도 낮았다. 진균, 세균, Pythium spp., Bacillus spp.의 토양내 밀도는 원주지역에서 낮았으나 B/F치는 서산, 태안지역보다 높았다. 완주지역에서 발병이 낮았던 것은 이 지역의 생강이 주로 답전윤환의 작부형태로 논에서 재배되기 때문으로 생각된다. 뿌리썩음병의 발병정도와 재배토양의 이화학적성상과의 상관은 관찰되지 않았다. 이 밖에도 초년재배, 답전윤환, 비가림 재배, 지하점적관수, 사양토 토양, 배수가 양호한 포장, 산간경사지 포장, 종강소독 등은 뿌리썩음병의 발병을 적게 하는 요인들이었다.

• Korean Journal of Environment and Ecology
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• v.32 no.3
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• pp.274-288
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• 2018

This study investigated the environmental factors and fish assemblage in 42 wetlands between spring and autumn of 2017 to evaluate the fish distribution and deduce the management strategy for improving biodiversity in created wetlands located at the Nakdong River basin. The investigation identified a total of 30 fish species and found that the most of wetlands were dominated by exotic fishes such as Micropterus salmoides and Lepomis macrochirus. Fish species such as Rhinogobius brunneus, Opsariichthys uncirostris amurensis, Zacco platypus were less abundant in the area with high density of Micropterus salmoides (static area) because they preferred the environment with active water flow. The pattern analysis of fish distribution in each wetland using the self-organizing map (SOM) showed a total of 24 variables (14 fish species and 10 environmental variables). The comparison of variables indicated that the distribution of fish species varied according to water depth and plant cover rate and was less affected by water temperature, pH, and dissolved oxygen. The plant cover rate was strongly associated with high fish density and species diversity. However, wetlands with low plant biomass had diversity and density of fish species. The results showed that the microhabitat structure, created by macrophytes, was an important factor in determining the diversity and abundance of fish communities because the different species compositions of macrophytes supported diverse fish species in these habitats. Based on the results of this study, we conclude that macrophytes are the key components of lentic freshwater ecosystem heterogeneity, and the inclusion of diverse plant species in wetland construction or restoration schemes will result in ecologically healthy food webs.

• Korean Journal of Ecology and Environment
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• v.35 no.3 s.99
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• pp.181-186
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• 2002

To evaluate the eutrophication status of the Asan Reservoir in Korea, physicochemical parameters were analyzed for samples of 19 sampling stations collected in the period from March to November in 1997. Water temperature was in the range of $8.3{\sim}35.3{\circ}^C$, with thermocline appearing in summer. Dissolved oxygen also showed similar verticle variation to temperature. Secchi depth was very shallow with a range of 0.1~1m. Suspended solids ranged from 11.3 mg/1 to 2143.3 mg/1, and seemed to be affected by the amount of rainfall and the standing stocks of phytoplankton. Nutrient concentrations were higher in tributaries, and decreased with downflow. Nutrients were low in the summer and early autumn when algal blooms occur, and high in the early spring and winter. The Trophic State Index showed that the Asan Reservoir is in a hypertrophic condition．

• Korean Journal of Ecology and Environment
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• v.35 no.3 s.99
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• pp.152-159
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• 2002

The seasonal variations of nitrifying bacterial population sampled from 3 sites in Moon-Chon reservoir were analyzed by in situ hybridization with fluorescently labeled rRNA-targeted oligonucleotide probes from August 2000 until July 2001. In addition, physico-chemical parameters such as temperature, pH, chi-a and DOC were measured to determine correlations between those factors and the size of nitrifying bacterial populations. Total bacterial numbers varied in the range of $0.8{\sim}1.5{\times}10^6\;cells/ml$ independent of sites and had the maximal values in March at all 3 stations. The ratio of eubacteria to total bacteria ranged from 44.9% to 79.5%, and the ratio of each nitrifying bacteria to eubacterial numbers reached only $1.0{\sim}7.4%$. The variations of ammonia-oxidizing bacteria ranged from $1.1{\times}10^4$ to $3.0{\times}10^4\;cells/ml$ without noticeable peak values whereas those of nitrite-oxidizing bacteria varied in $1.3{\sim}5.7{\times}10^4\;cells/ml$ with the increasing tendency in winter regardless of the sites. Moreover it was observed that the numbers of nitrite-oxidizing bacteria were higher than those of ammonia-oxidizing bacteria. Total bacterial numbers correlated with water temperature (r = 0.355, p<0.05) and DOC (r = 0.58G, p<0.01) positively whereas nitrite-oxidizing bacteria correlated with temperature (r = -0.416, p<0.05) and pH (r = -0.568, p = 0.001) negatively. In addition, DOC represented good correlations with eubacterial numbers (r = 0.448, p<0.01). These results indicate that temperature, DOC and pH might be one of the main factors affecting variations of bacterial populations in the aquatic ecosystem. It was also suggested that FISH method is a useful tool for detection of slow growing nitrifying bacteria.