• Korean Journal of Food Science and Technology
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• v.22 no.3
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• pp.278-284
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• 1990

A study relating the soluble-solids (S.S.) contents of Chinese cabbages to the final titratable acidities(TA) of kimchis was conducted. The S.S. contents of Spring-sowed Chinese cabbages were in the range from $1.20-3.40^{\circ}$ Brix while those of Autumn-sowed Chinese cabbages were in the range from $3.8-6.6^{\circ}$ Brix. The S.S. contents of Chinese cabbages were varing depending on their varieties and the cultivating seasons. However, seasonal variations were much more significant than the varietal variations. The final TAs of kimchis after complete fermentation were found to be directly proportional to the S.S. contents(x) of Chinese cabbages, showing that TA equals to 0.30x+07779. From the equation, a Chinese cabbage of a S.S. content with up to $0.02^{\circ}$ Brix, which is practically impossible to obtain, will make a kimchi which will not be overacidified during the prolonged storage period without any preservative measures.

• Journal of the Korea Organic Resources Recycling Association
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• v.10 no.2
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• pp.65-70
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• 2002

The previous studies showed that rumen microorganisms had an enhanced waste-degrading capability and controlling the dilution rate was very effective in improving acidification efficiency. Generally the composition of food waste has a small deviation value, but one of the waste components (grains, vegetables or meats) can be increased dramatically depending on a seasonal variation. Thus, it is important to evaluate the efficiency of acidogenic fermentation in this case. Each component was spiked to be 80% of the total waste in R1 (grains), R2(vegetables), and R3 (meats). In Rl, rapid degradation occurred during the initial two days. R2 showed similar performance to that of general food waste. In R3, degradation retarded in the initial stage and then increased after controlling the dilution rate. The acidification efficiencies of the reactors were 88.7 (R1), 73.5 (R2), and 62.1% (R3), respectively. Therefore, the fermentation efficiency was kept over 62% regardless of waste components, indicating that it was stable to acidify food waste by employing rumen microorganisms and controlling the dilution rate.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.589-592
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• 2008

This study was conducted to assess the durability of Chloride-inhibiting Low-Heat Cement while being subjected to freezing-thawing during winter seasons. Although durability varies slightly depending on the conditions of the jobsite, frost damage to concrete resulting from repeated freezing and thawing over the course of seasonal changes is the leading cause behind lowered concrete durability. in addition, concrete that has been subjected to freezing and thawing during the winter season develops a significant amount of expansive force at the core and begins to exhibit signs of damage, such as cracking, peeling, and detachment from the aggregate. Therefore, this study fabricated test specimens using a Chloride-inhibiting Low-Heat Cement(CLC) and the widely used blast furnace slag cement(BFS) and Ordinary Portland Cement(OPC) with water-to-cement ratios of 35%, 40% and 45%, respectively, to assess the durability index of the CLC as per resistance to freezing-thawing. The specimens were then tested using the KS F 2456 method (Testing method for resistance of concrete to rapid freezing and thawing) to measure the dynamic modulus of elasticity. The dynamic modulus of elasticity measurements were then used to derive the durability indices. By comparing the durability indices, it was confirmed that CLC, BFS, and OPC all had superior durability.

• Journal of the Korean Society of Industry Convergence
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• v.21 no.5
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• pp.227-234
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• 2018

The smart irrigation system using ICT technology is crucial for stable production of upland crops. The objective of this study was to develop a smart irrigation system that can control soil water, depending on irrigation methods, in order to improve crop production. In surface irrigation, three irrigation methods (sprinkler irrigation (SI), surface drip irrigation (SDI), and fountain irrigation (FI)) were installed on a crop field. The soil water contents were measured at 10, 20, 30, and 40 cm depth, and an automatic irrigation system controls a valve to maintain the soil water content at 10 cm to be 30%. In subsurface drip irrigation (SSDI), the drip lines were installed at a depth of 20 cm. Controlled drainage system (CDS) was managed with two ground water level (30 cm and 60 cm). The seasonal irrigation amounts were 96.4 ton/10a (SDI), 119.5 ton/10a (FI), and 113 ton/10a (SI), respectively. Since SDI system supplied water near the root zone of plants, the water was saved by 23.9% and 17.3%, compared with FI and SI, respectively. In SSDI, the mean soil water content was 38.8%, which was 10.8% higher than the value at the control treatment. In CDS, the water contents were greatly affected by the ground water level; the water contents at the surface zone with 30 cm ground water level was 9.4% higher than the values with 60 cm ground water level. In conclusion, this smart irrigation system can reduce production costs of upland crops.

• Journal of The Korean Society of Grassland and Forage Science
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• v.35 no.2
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• pp.112-118
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• 2015

This study was carried out to offer basic information for the promotion of the goat industry and the improvement of mountainous-pasture management by investigating seasonal changes in forage and livestock productivity according to the grazing-pasture type. The forage productivity of rangeland was the highest (p < 0.05) in summer and decreased in autumn; but that of pasture was the largest (p < 0.05) in spring and had relatively stable productivity with minor seasonal differences, although it decreased slightly in autumn. The dry matter content was not seasonally different at pasture, but it was changeable from spring to autumn at rangeland. The crude protein content increased in autumn at pasture (p < 0.05), and decreased in summer and autumn compared with spring at rangeland. The crude fiber content was lower and the ether extract was higher at pasture compared with rangeland. The average daily gain of the goats was different depending on forage productivity and pasture type; consequently, the lowered forage productivity at rangeland compared with pasture means that rangeland needs to be changed or improved to a pasture type that provides a more effective grazing system for goats.

• Korean Journal of Ecology and Environment
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• v.42 no.3
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• pp.382-393
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• 2009

The objectives of this study were to characterize long-term annual and seasonal trophic state of Topjeong Reservoir using conventional variables of Trophic State Index (TSI) and to determine the empirical relations between the trophic parameters. For the analysis, we used water quality dataset of 1995$\sim$2007, which is obtained from the Ministry of Environment, Korea and the number of parameters was 9. Annual ambient mean values of TN and TP were 1.78 mg $L^{-1}$ and 0.03 mg $L^{-1}$, respectively and TN : TP ratios averaged 76, indicating that this system was nitrogen-rich hypertrophic, and was probably phosphorus-limitation for algal growth. Therefore, nitrogen varied little with seasons and years, and total phosphorus (TP) varied depending on season and year. Monsoon dilutions of TP occurred in August and monthly fluctuations of suspended solid (SS) was similar to those of chlorophyll-$\alpha$ (CHL). Annual mean values of BOD and $COD_{Mn}$ were 1.61 mg $L^{-1}$ and 4.23 mg $L^{-1}$, respectively and the interannual values were directly influenced by the intensity of annual rainfall. There were no significant differences in the trophic variables between the two sampling sites. Mean values of Trophic State Index (TSI, Carlson, 1977), based on TN, TP, CHL, and SD (Secchi depth), turned out as eutrophic state, except for the TN (hypertrophic). Regression analyses of log-transformed seasonal CHL against TP and TN showed that variation of the CHL was explained 37% by the variation of TP ($R^2$=0.37, p<0.001, r=0.616), but not by TN ($R^2$=0.03, p>0.05). Regression coefficient of $Log_{10}$CHL vs $Log_{10}SD$ was 0.330 (p<0.003, r=0.580), indicating that transparency is regulated by the organic matter in the system. Results, data suggest that one of the ways controlling the eutrophication would be a reduction of phosphorus from the watershed.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.18 no.4
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• pp.214-226
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• 2013

To understand the changing patterns in phytoplankton communities, we conducted 12 surveys along the Nakdong River, its estuary, and adjacent coastal areas between January 2011 and October 2012 (during the period of barrage construction and sediment dredging). Monthly precipitation ranged from 0 to 502 mm during the survey period, and salinity ranged between 0.1 psu and 0.3 psu in the Nakdong River, regardless of the depth, indicating no seawater influence, while salinity showed large seasonal fluctuations in the estuarine and coastal station, ranging from 0.1 psu to 34.8 psu. A total of 402 phytoplankton species were identified, 178 species from the river and 331 species from the estuary and coastal areas. Phytoplankton standing crop increased in 2012 compared to that in 2011, and was found to be highest in the river, followed by the estuary and coastal areas. Among the top 20 species in frequency of occurrence and dominance, Stephanodiscus spp., Aulacoseira granulata, and Aulacoseira granulata var. angustissima and Pseudo-nitzschia spp. were important species along the river-estuary-coastal areas. Diatoms were the major taxonomic group inhabiting the Nakdong river-estuary-coastal areas. A comparison of seasonal dominant phytoplankton species revealed a slight decrease over the years, from 13 species in 2011 to 10 species in 2012. However, no significant difference was found in the diversity of phytoplankton species between the two survey years, although lightly greater diversity was observed in the coastal areas than in the river and estuary. Cluster analysis with community composition data revealed that the community structure varied significantly in 2011 depending on the time of survey, while in 2012, it hardly showed any variation and was simpler. An increase in the phytoplankton standing crop, fewer dominant species, and simpler community structure in 2012 compared to those in 2011 are probably due to the rapid environmental changes along the Nakdong River. To investigate these ecological relationships, it is necessary to conduct further studies focusing on integrated analyses of biocenosis, including phytoplankton with respect to the changes in nutrient distribution, variation of freshwater discharge, and effect area of freshwater in the Nakdong estuary and adjacent coastal areas.

• Korean Journal of Ecology and Environment
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• v.48 no.2
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• pp.95-107
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• 2015

In order to identify long-term trends of water quality parameters in Lake Kyeongpo, Mann-Kendall test, Sen's slope estimator and linear regression were applied on data, with 15 parameters from three different sites and rainfall, monitored once in every two months from March to November during 1998~2013. Seasonal variation analysis only used Mann-Kendall test and Sen's slope estimator. Analysis result showed that salinity, transparency and nutrient variables (total phosphorus, dissolved inorganic phosphorus, total nitrogen, nitrate nitrogen, ammonia nitrogen) were only parameters having statistically significant trend. In linear regression analysis, salinity (surface and bottom layer of all sites) and transparency (only at site 1), were figured out with statistically significant increasing trend, while in non-parametric statistical method, salinity and transparency in all sites (surface, middle, deep) were figured out with statistically significant increasing trend. Water quality parameters showing statistically significant decreasing trends were dissolved oxygen (surface layer of site 1 and bottom layer of sites 2 and 3), total phosphorus (sites 1 and 2), dissolved inorganic phosphorus, total nitrogen, nitrate nitrogen and ammonia nitrogen in the linear regression analysis and, dissolved oxygen (bottom layer of all sites), total phosphorus, dissolved inorganic phosphorus, total nitrogen, nitrate nitrogen and ammonia nitrogen in the non-parametric method. Seasonal trend analysis result showed that salinity, turbidity, transparency and suspended solids in spring, salinity, transparency, nitrate nitrogen and suspended solids in summer and temperature, salinity, transparency and suspended solids in fall were the variables depending on the season with increasing trends. In general, rainfall during the research period showed decreasing trend. The significant reduction trends of nutrients in Lake Kyeongpo were believed to be related to lagoon restoration and water management project run by Gangneung city and under-water wear removal, but further detailed studies are needed to know the exact causes.

• Journal of Korean Society of Forest Science
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• v.94 no.6
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• pp.488-495
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• 2005

This study was conducted to understand the influences of forest structure on throughfall, stemflow and interception loss. The study plots included the natural old-growth deciduous, Pinus koraiensis and Abies holophylla forests in Gwangneung and the rehabilitated young mixed forest in Yangju, Gyeonggido. The Pinus koraiensis and Abies hotophylla had been planted in 1976. The rehabilitated young mixed forest had been established to control erosion in 1974. Total and net rainfall were monitored from March, 2003 to October, 2004. Tipping bucket rain gauge recorded total rainfall. Throughfall and stemflow were measured by custom-made tipping bucket and CR10X data logger at each $10m{\times}10m$ plots at intervals of 30 minutes. Interception loss in the Pinus koraiensis plot were most as 37.2% of total rainfall and least as 22.6% in the rehabilitated young mixed forest. Stemflow in the rehabilitated young mixed forest was 10.7% of total rainfall and stemflow in the Pinus koraiensis plot was 2.4%. The average throughfall ratio ranged from 66% to 77% depending on the canopy coverage. The relationship of stemflow and total rainfall represented in a linear regression equation though the variation of data was large. The ratio of stemflow-conversion was 2% of total rainfall in the Pinus koraiensis plot and 12% in the rehabilitated young mixed forest, respectively. The stem storage of the natural old-growth deciduous was the largest of 0.21 mm whereas that of the Pinus koraiensis plot was the least of 0.003 mm. A deciduous forest produced stemflow more than a coniferous forest due to a smooth bark and steeply angled branches. Interception loss of all study plots increased linearly as total rainfall increased. The distribution of interception loss data related in total rainfall became wider in a deciduous forest than a coniferous. It resulted from seasonality of leaf area index in a deciduous forest. As considered above results, it was confirmed that there were great differences of throughfall, stemflow and interception loss depending on forest stand structures. The simulation model for predicting interception loss must have parameters such as forest stand characteristics and LAI in order to describe the influence of forest structure on interception loss.

• Korean Journal of Environmental Biology
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• v.33 no.2
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• pp.240-247
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• 2015

This study was carried out to provide the preliminary data for study of zooplankton community structures and coastal pelagic ecosystem by understanding the seasonal change of zooplankton community depending on environmental factors at Dangdong bay in Tongyeong city. In this study, the environmental factors and the change of zooplankton community were analyzed for 2008 to 2011. In the results, a total of 80 species of zooplankton was sampled with a mean density of $1,599inds.m^{-3}$. The dominant species changed seasonally, and the most dominant species was Acartia steueri in winter and spring, Penilia avirostris in summer, and Evadne nordmanni in autumn. The Canonical Correspondence Analysis was conducted between the major dominant species and environmental factors. And for the environmental factors that effect the zooplankton community, the high correlation was observed with the water temperature, COD, DO and T-N, though there was slight difference among species. Therefore, more various research and environmental study are necessary to understand of planktonic ecosystem because the zooplankton community is affected by the interaction of both physical and biological factors.