• Korean Journal of Agricultural Science
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• v.46 no.4
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• pp.999-1006
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• 2019

Recently, the quantitative management of agricultural water supply, which is the main source for water consumption in Korea, has become more important due to the effective water management organization of the Korean government. In this study, the estimation method for irrigation supply based on agricultural reservoir storage data was improved compared to previous research, in which drought year selection was unclear, and the outlier data for the rainfall-irrigation supply were not eliminated in the regression analysis. In this study, the drought year was selected by the ratio of annual precipitation to mean annual precipitation and the storage rate observed before the start of irrigation. The outlier data for the rainfall-irrigation supply were eliminated by the Grubbs & Beck test. The proposed method was applied to nine agricultural reservoirs for validation. As a result, the ratio of annual precipitation to mean annual precipitation is less than 53% and the storage rate observed before the start of irrigation is less than 55% it was judged to be the drought year. In addition, the drought supply factor, K, was found to be 0.70 on average, showing closer results to the observed reservoir rates. This shows that water management at the real is appling drought year practice. It was shown that the performance of the proposed method was satisfactory with NSE (Nash-Sutcliffe model efficiency coefficient) and R² (coefficient of determiniation) except for a few cases.

• Journal of Korea Water Resources Association
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• v.42 no.4
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• pp.297-307
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• 2009

For reliable water quality simulation by semi distributed model, accurate daily runoff simulation should have preceded. In this study, newly developed channel routing method which is nonlinear storage method is combination of Muskingum routing method and variable storage routing method and temporally weighted average curve number method were applied for effect analysis of water quality simulation. Developed modules, which are added in SWAT models and simulation, were conducted for the Chungju dam watershed. The simulation result by each module applied effect. As a result of analysis contribute water quality modeling, nonlinear storage method is more effective than temporally weighted average curve number method. Nutrient loading discharge was affected by development of runoff delaying from improvement of channel routing, because of characteristics of nonpoint source pollution.

• Proceedings of the Korea Water Resources Association Conference
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• 2023.05a
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• pp.167-167
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• 2023

Soil organic carbon (SOC) is a critical component of soil health and is crucial in mitigating climate change by sequestering carbon from the atmosphere. Accurate estimation of SOC storage is essential for understanding SOC dynamics and developing effective soil management strategies. This study aimed to investigate the factors influencing the spatial distribution of SOC storage in South Korea, using bulk density (BD) prediction to estimate SOC stock. The study utilized data from 393 soil series collected from various land uses across South Korea established by Korea Rural Development Administration from 1968-1999. The samples were analyzed for soil properties such as soil texture, pH, and BD, and SOC stock was estimated using a predictive model based on BD. The average SOC stock in South Korea at 30 cm topsoil was 49.1 Mg/ha. The study results revealed that soil texture and land use were the most significant factors influencing the spatial distribution of SOC storage in South Korea. Forested areas had significantly higher SOC storage than other land use types. Climate variables such as temperature and precipitation had a relative influence on SOC storage. The findings of this study provide valuable insights into the factors influencing the spatial distribution of SOC storage in South Korea.

• Food Science and Preservation
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• v.9 no.2
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• pp.154-160
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• 2002

This study was carried out to investigate the efficacy of electrolyzed oxidizing(EO) water, electrolyzed oxidizing water with 0.5% citron juice and 0.1% aluminium potassium sulfate (APS) solution as the storing liquids to maintain quality and extend shelf life of peeled taro. Water content of peeled taro increased from 80.55% to 82.12∼84.24% after 25 days storage due to moisture absorption. However, there were no significant difference between treatments. In case of color value of peeled taro, L value was slowly decreased and a, b value was generally increased. Texture of peeled taro decreased from initial 4,520$\pm$75 g to 4,160$\pm$80 g after 25 days storage in EO water with 0.5% citron juice, which is the least reduction value in all treatments. Treatment of EO water with 0.5％ citron juice maintained 6.99 mg%(57%) of total vitamin C after 25 days storage which showed highest total vitamin C content between treatments. In most treatments, total sugar was decreased in fast rate for 15 days storage and slowly decreased after 15 days storage. Free sugar content was not changed significantly during storage. In case of sucrose content which is the major portion of free sugar, reduction continued until the midst of storage. and after that it increased to 1.5∼2 times of initial contents. However, there were no differences between treatments and storage days in contents of fructose, glucose and maltose. Major amino acids in peeled taro were aspartic acid and glutamic acid with 1,084.8 and 691.8 mg/100g respectively. At 25 days of storage, aspartic acid content in treatment of EO water was increased about 13.9%. Treatment of EO water with 0.5% citron juice was the most effective in respect to the reduction ratio of total amount of essential amino acids.

• Solar Energy
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• v.8 no.2
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• pp.46-56
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• 1988

This investigation concerns thermal stratification of the water due to the temperature difference (${\Delta}T=T_{\infty}-T_i$) between the mean temperature of the water in the test tank (1m wide, 1m high, 2.1m long) and the temperature of the inflow water into the tank; flow rate of circulating water and height of the sink diffuser in the test tank. The additional objectives was to observe a stratification phenomena near an interface by measuring the velosities and the temperature difference and investigate an availabilities of the better effective hot water through establishing thermocline near an interface around the bottom of the tank. Following results were obtained through the experiments. 1. When the flow rate was constant and the temperature difference (${\Delta}T=T_{\infty}-T_i$) between the mean temperature of the flow in the test tank and the temperature of the inflow water increased by 5.6, 9.5, 13.5($^{\circ}C$), obtained the better effective advantage of hot water and the stress near an interface increased gradually. 2. When the ${\Delta}T=T_{\infty}-T_i$ was constant and flow rate increased by 4.0, 4.8, 6.4, 8.0 (LPM), obtained the better effective advent age of hot water and the mean stress near an interface increased gradually. 3. When the height of the sink diffuser was 25cm from tank bottom in comparison with 50cm, obtained the better effective advantage of hot water and the mean stress near an interface increased.

• Food Science and Preservation
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• v.12 no.3
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• pp.252-256
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• 2005

For increasing shelf-life, melons with different washing and packaging were evaluated during storage at room temperature. Hardness and weight of melon was decreased during storage period and, after 12 days, severe rotten or decay appeared on melons except melon with ozone-water. Organoleptic test on color, appearance, taste and texture showed maximum values on melons eith ozone-water washing. Particularly, spots have been shown on all packaged melons in the later storage, except melons washed with ozone-water. According to these results, ozone-water washing was effective for keeping the high quality of melons.

• Proceedings of the Korea Water Resources Association Conference
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• 2005.05b
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• pp.1403-1407
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• 2005

In order to analyze the water storage of the Daecheong dam after constructing the Yongdam dam situated in upstream, a daily cascaded simulation model for analyzing water storages in the Yongdam-Daecheong dams was developed. Operation scenarios of the Yongdam dam were selected to 8 cases with the combinations of downstream outflows and water supplies to the Jeonju region. Daily water storages in the Daecheong dam was analyzed daily by simulating from 1983 to 2004. The results are summarized as follows. Firstly, water supplies from the Daecheong dam were analyzed to amount $1,964.2Mm^3$ on a yearly average in case without the Yongdam dam. In case with the Yongdam dam, water supplies from the Daecheong dam were analyzed to amount $1,858.7\~1,927.3Mm^3$ in case with downstream outflow of $5\;m^3$ is, and were analyzed to amount $1,994.9\~2,017.8Mm^3$ in case with downstream outflow of $10\;m^3/s $. These values are compared to $1,649Mm^3$ applied in design. Secondly, reservoir use rate which was defined rate of water supply to effective water storage reached $241.3\% in case without the Yongdam dam. In case with the Yongdam dam, reservoir use rate reached $228.3\~236.8\% In case with downstream outflow of $5\;m^3/s$, and reached $245.1\~247.9\% in case with downstream outflow of $10\;m^3/s$. Thirdly, runoff rate which is defined rate of dam inflow to areal rainfall reached $57.3\% in case without the Yongdam dam. In case with the Yongdam dam, reservoir use rate reached $62.0\~68.4\% in case with downstream outflow of $5\;m^3/s$, and reached $64.1\~68.5\% in case with downstream outflow of $10\;m^3/s$. Fourth, in case with downstream outflow of $10\;m^3/s$ is from the Yongdam dam, appropriate water supply amounts to the Jeonju region were analyzed to only $0.50Mm^3/day$ from the daily simulation of water storages in the Yongdam dam. Comprehensively, water supply capacity of the Daecheong dam was analyzed to affect in small amounts in spite of the construction of the Yonsdam dam. It is effected to achieve the effective water management of the Yongdam dam and the Daecheong dam by using the developed cascaded model.

• Journal of Biosystems Engineering
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• v.39 no.1
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• pp.34-38
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• 2014

Purpose: In this study, the performance of cooling system with the water-water heat pump system of 100kW scale made for cooling agricultural facilities, especially for horticultural facilities, was analyzed. It was intended to suggest performance criteria and performance improvement for the effective cooling system. Methods: The measuring instruments consisted of two flow meters, a power meter and thermocouples. An ultrasonic and a magnetic flow meter measured the flow rate of the water, which was equivalent to heat transfer fluid. The power meter measured electric power in kW consumed by the heat pump system. T-type thermocouples measured the temperature of each part of the heat pump system. All of measuring instruments were connected to the recorder to store all the data. Results: When the water temperature supplied into the evaporator of the heat pump system was over $20^{\circ}C$, the cooling Coefficient Of Performance(COP) of the system was higher than 3.0. As the water temperature supplied into the evaporator, gradually, lowered, the cooling COP, also, decreased, linearly. Especially, when the water temperature supplied into the evaporator was lower than $15^{\circ}C$, the cooling COP was lower below 2.5. Conclusions: In order to maintain the cooling COP higher than 3.0, we suggest that the water temperature supplied into evaporator from the thermal storage tank should be maintained above $20^{\circ}C$. Also, stratification in the thermal storage tank should be formed well and the circulating pumps and the pipe lines should be arranged in order for the relative low-temperature water to be stored in the lower part of the thermal storage tank.

• Korean journal of food and cookery science
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• v.24 no.6
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• pp.748-756
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• 2008

This study was conducted to investigate the antioxidant activity of hot water extracts of wa-song (Orostachys japonicus A. Berger) dried using hot air (HWE) and frozen (FWE). Varying levels (0.1, 0.5 and 1.0 g/100 g) of HWE and FWE were added to soybean oil and lard. Chromaticity, anisidine value, acid value, peroxide value (POV) and thiobarbituric acid (TBA) value in oils were measured periodically during their storage for 28 days at $60^{\circ}C$. The chromaticity of edible oils showed a general increas with prolonged storage as well increasing levels of extracts. The anisidine value was not significantly increased during storage for 14 days, but was significantly increased after storage for 21 days in soybean oil and lard. The anisidine value of HWE on soybean oil was $12.60{\pm}0.92{\sim}13.82{\pm}0.68$ after storage for 28 days its value was lower than that of the control and buthylated hydroxy anisol (BHT). The antioxidant activity of HWE was found to be more effective than that of FWE. The acid value of HWE was significantly increased during storage from 14 to 21 days in soybean oil and from 7 to 14 days in lard. The antioxidant activity of FWE was particulary effective at the primary stage of the reaction system of lard storage. POV was highly increased during the storage periods between 7 and 14 days in soybean oil. The antioxidant activity in all the samples tested did not significantly increase after storage for 14 days, except when 0.1 g/ 100 g of FWE added to lard. TBA values of all the samples were lower than that of control and 0.02% BHT during their storage. The antioxidant activities of wa-song within the reaction system of oils were more effective in soybean oil than in lard.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2002.10a
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• pp.13-16
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• 2002

Operation of experimental site on the rural water is necessary to research on the effective development and management of agricultural water. Hydrological data on the watershed runoff, reservoir storage, irrigation and drainage are measured and accumulated. For the monitoring system of the experimental site, four rainfall gauging stations and twenty-six water level gauging stations are established and operated. Analysis of measured data are processed for rainfall amount and intensity, water level and discharge.