• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2001.04a
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• pp.98-103
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• 2001

In order to understand the characteristics of leachate at the Seokdae municipal waste landfill in the Pusan city, the correlation between leachate pollution loading and volume of gas production. concentration of gas and subsidence of ground, the characteristical methos, geochemical analyses and laboratory column tests using samples of gases, leachate and surface soil of Seokdae waste landfill area. Through the analysis of water balance, leachate flow rate and pollution loading were estimated. Geistatistical analysis of four gas components ( $O_2$, C $H_4$, $H_2$S and CO) shows the possibility of ground subsidence around the group of a site with high concentration of gas. From geochemical analyses of leachate, EC and Total-Alkalinity of ground subsidence around the group of a site with high concentration of gas. From geochemical analysis of leachate, Ec and Total-Alkalinity were increased, and Cl, Cr, Mn, Cu, Zn, Cd and Pb were decreassed comparing to the part, and the type of water quality was Na-HC $O_3$ in trilinear diagram. It shows that biodecomposition of municipal wastes continues actively. From the analysis of water balance, the total leachate flow rate is about 465.11㎥/day and pure pollution loading of Cl, Mn and Fe are estimated to 223.8kg/day, 0.2kg/day, 0.3kg/day, respectively. The laboratory column test of residual soil and landfill soil shows 0.206cm and 0.019cm for linear velocity(equation omitted), 0.234 $\textrm{cm}^2$/min and 0.018$\textrm{cm}^2$/min for diffusion coefficient ( $D_{ι}$), and 1.136cm and 0.095cm longitudinal dispersion index ($\alpha$$_{ι}$), respective]y. It demonstrates that the delay time of contamination for residual soil is shorter than that of landfill soil.

• Korean Journal of Poultry Science
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• v.33 no.1
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• pp.57-63
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• 2006

This study was conducted to investigate the effect of ventilating system of environmental controlled broiler house on broiler production. Three hundred eighty four broiler chicks (Hubbard, mean live weight of $44.5{\pm}2.0g/bird$) were reared for 2 wk. The results of the present study were summarized as follows : 1. Ammonia gas production was lower in the second and the third floors of cages compared with first floor of cages 13.5 and 13.5 vs 14.6 ppm, respectively). The observations of ammonia production in the morning and afternoon were similar. The production of carbon dioxide was not different between morning and afternoon, but it was tended to decrease in the forth floor of cages due to a fresh air 2. A wind velocity in the enclosed house was similar across lower, middle and upper section (0.57m/sec, 0.22m/sec and 0.04msec, respectively). In order to maintain an optimal air flow velocity in the cages, the duct entrance was punched, and then the air flow was full-round in the overall space in the cage. 3. Daily liveweight gain, feed intakes, and feed efficiency were not significant differences among treatments during whole experimental period (P>0.05). Therefore, the present results showed that temperature, moisture and atmosphere controlling were desirable, and air flew evenly in the cage.

• Journal of Korean Society of Forest Science
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• v.94 no.6
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• pp.496-503
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• 2005

This study was conducted to investigate the influences of sapflow flux on soil water tensions and soil moisture content at the Abies holophylla plots in Gwangneung, Gyeonggido, from September to October 2004. The Abies holophylla had been planted in 1976 and thinning and pruning were carried out in 1996 and 2004. Sapflow flux was measured by the heat pulse method, and soil water tension was measured by tensiometer at hillslope and streamside. Time domain reflectometry probes (TDR) were positioned horizontally at the depth of 10, 30 and 50 cm to measure soil moisture content. All of data were recorded every 30 minutes with the dataloggers. The sapflow flux responded sensitively to rainfall, so little sapflow was detected in rainy days. The average daily sapflow flux of sample trees was 10.16l, a maximum was 15.09l, and a minimum was 0.0l. The sapflow flux's diurnal changes showed that sapflow flux increased from 9 am and up to 0.74 l/30 min. The highest sapflow flux maintained by 3 pm and decreased almost 0.0 l/30 mm after 7 pm. The average soil water tensions were low ($-141.3cmH_2O$, $-52.9cmH_2O$ and $-134.2cmH_2O$) at hillslope and high ($-6.1cmH_2O$, $-18.0cmH_2O$ and $-3.7cmH_2O$) at streamside. When the soil moisture content decreased after rainfall, the soil water tension at hillslope responded sensitively to the sapflow flux. The soil water tension decreased as the sapflow flux increased during the day time, whereas increased during the night time when the sapflow flux was not detected. On the other hand, there was no significant relationship between soil water tension and sapflow flux at streamside. Soil moisture content at hillslope decreased continuously after rain, and showed a negative correlation to sapflow flux like a soil water tension at hillslope. As considered results above, it was confirmed that the response of soil moisture tension to sapflow flux at hillslope and streamside were different.

• Korean Journal of Agricultural Science
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• v.6 no.2
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• pp.166-184
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• 1979

In order to prevent the water loss in the irrigation canal constructed on the sandy gravel layer or on the other highly permeable ground layer, lining has been practiced. Many studies have been done so far on the lining method to prevent the water loss in the irrigation canal and recently studies on the lining with plastic film or polyethylene film were also reported. However, the plastic film or polyethylene film has low strength and is liable to break, and water loss from pin hole caused by contacting with sand or gravel is highly predicted. This study was then conducted to find proper lining and buring method in canal construction of polypropylene mat after coated with vinyl, as one way to overcome the shortcoming frequently observed when plastic or usual polyehtylene film were used. Eventhough rather longer periods of experiments are needed to attain reliable and accurate results on the variation of durability, the durability of asphalt coated area, or on the damage due to freeze after burial or exposure of polypropylene mat, the experiemental results obtained during one year of period are summarized as follows: 1. The curvature at the area between canal bottom and side slope had increased stability and saved consruction cost. The relationship among the variation of curvature, the reduction of polypropylene mat and the reduced amount of soil cutting at each side slope was presented in Fig. 7 through 9. 2. The depth of covering material to protect polypropylene mat was desired to be over 30cm, considering the water depth, side slope, canal cleaning practices, traffic, or back pressure of irrigation period. 3. In order to increase the canal stability and to prevent slope erosion, sandy soil was required, to be placed under ground, and coarse gravel should cover the surface area of canal. 4. The studies on the stability of side slope in the canal should consider the passive area on the bottom and the slope should be about 1 to 2, considering the slope stability, allowable velocity and tractive force. 5. When compared with earth lining, the lining with polypropylene mat coated with vinyl was responsible to save 28% and 37% of canal lining cost, when the soil carrying distances were 500 and 700m. respectively. 6. The water interception was almost completely attained when the polypropylene mat coated with vinyl was used for lining. But further studies were assumed to be necessary for the use of asphalt since the strength of polypropylene mat connected with asphalt will vary with duration.

• Journal of Advanced Marine Engineering and Technology
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• v.40 no.3
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• pp.157-164
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• 2016

In this study, researchers performed preliminary design and numerical analysis for a pilot-scale helium heating system intended to support full-scale construction for a sulfur-iodine (SI) cycle. The helium heat exchanger used a liquefied petroleum gas (LPG) combustor. Exhaust gas velocity at the heat exchanger outlet was approximately 40 m/s based on computational thermal and flow analysis. The maximum gas temperature was reached with six baffles in the design; lower gas temperatures were observed with four baffles. The amount of heat transfer was also higher with six baffles. Installation of additional baffles may reduce fuel costs because of the reduced LPG exhausted to the heat exchanger. However, additional baffles may also increase the pressure difference between the exchanger's inlet and outlet. Therefore, it is important to find the optimum number of baffles. Structural analysis, followed by thermal and flow analysis, indicated a 3.86 mm thermal expansion at the middle of the shell and tube type heat exchanger when both ends were supported. Structural analysis conditions included a helium flow rate of 3.729 mol/s and a helium outlet temperature of $910^{\circ}C$. An exhaust gas temperature of $1300^{\circ}C$ and an exhaust gas rate of 52 g/s were confirmed to achieve the helium outlet temperature of $910^{\circ}C$ with an exchanger inlet temperature of $135^{\circ}C$ in an LPG-fueled helium heating system.

• Magazine of the Korean Society of Agricultural Engineers
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• v.14 no.3
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• pp.2703-2715
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• 1972

1. Title of Research Research on the Loss of Irrigation Water Flowing in Earth Channel. 2. Purpose and Importance of Research The purpose of this research is to obtain the accurate loss rated of irrigation water flowing in earth channels so as to give a criterion of designing rational and effective suplpy project of irrigations water. It is the present status that the loss rates of 10 to 20% are obscurely applied without any scientific proof. Therefore, the importance of this research lies in securing loss rates, which are experimentally proves to be suitable for specific local conditions. 3. Content and Scope of Research The selected test reach of the main channel is 1,000m long. Discharges were measured at up and downstream enps by using current meter. The test reach of the lateral channel is 500m long, and parshall flumes were set at both ends to measure inflow and outflow. Finally, for the supply ditch, the test section is 200m long, and sharp-edged rectangular weirs were provided at both ends to measure inflow and outflow. In addition, various factors influence on the loss of irrigation water in channel wer examined. 4. Results of Research and Proposition Results: 1. In the main channel, which is 1,000 M long, and has a slope of 1/3,000 and was constructed by cutting earth, its loss rate is 9.64%. 2. In the lateral, which has a slope of 1/1,500, and is 500m long, and was constructed by cutting, its loss rate is 15.55%. Its average seepage rate is 2.08cm/day. 3. In the supply ditch, which has a slope of 1/300, and is 200m long, and was constructed by filling earth, its loss rate is 12.34%, its average seepage rate being 3.37cm/day. Proposition: As could be seen in the results above-mentioned, it is contradictory to apply a loss rate of 20% for every main channels and 15% for every laterals without variation, as done so for in planning irrigation project. The fact, however, is that loss rates must be different according to localities and characteristics. Due to the fact that this experiment is small in its scope and is nothing but a preliminary one, it is hardly possible to draw decisive conclusions with the results obtained in this research. Loss rates, that are secured through more extensive research, should be used, in order to establish precise irrigation project. Moreover, such researches should be carried out for a number of loclities throughout the nation.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.6
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• pp.590-598
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• 2005

An adequate method to identify chromium separation, Cr(III) and Cr(VI), in water samples were studied by using High Performance Liquid Chromatography(HPLC) coupled with Inductively Coupled Plasma Mass Spectometer(ICP-MS) equipped with Dynamic Reaction Cell(DRC). The characteristic distribution of Cr(III) and Cr(VI) in the raw water taken at the six water intake stations in Seoul, was analyzed by the method developed by the authors. The chromium species separated by HPLC was isocratically conducted by using tetrabutylammonium phosphate monobasic(1.0 mM TBAP), ethylenediaminetetraacetic acid(0.6 mM EDTA) and 2% v/v methanol as the mobile phase. 5% v/v methanol was used as flushing solvent. A reactive ammonia($NH_3$) gas was used to eliminate the potential interference of $ArC^+$. Several Parameters such as solvent ratio, pH, flow rate and sample injection volume were optimized for the successful separation and reproducibility. Although it has been reported thai the separation sensitivity of Cr(III) is superior to that of Cr(VI), the authors observed Cr(VI) was more sensitive than Cr(III) when ammonia($NH_3$) gas was used as the reaction gas. It took less than 3 minutes to analyze chromium species with this method and the estimated detection limits were $0.061\;{\mu}g/L$ for Cr(III) and $0.052\;{\mu}g/L$, for Cr(VI). According to the results from the analysis on chromium species in the raw water of the six intake stations, the concentrations of Cr(III) ranged from 0.048 to $0.064\;{\mu}g/L$(ave. $0.054\;{\mu}g/L$) while that of Cr(VI) ranged from 0.014 to $0.023\;{\mu}g/L$(ave. $0.019\;{\mu}g/L$). Recovery ratio was very high($90.1{\sim}94.1%$). There were two or three times more Cr(III) than Cr(VI) in the raw water.

• Journal of the Korean Society of Food Science and Nutrition
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• v.46 no.2
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• pp.210-219
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• 2017

This study aimed to establish an optimal extraction process and high-performance liquid chromatography (HPLC)-photodiode array (PDA) analytical method for determination of marker compounds, dihydrokaempferol (DHK) and 3-O-methylquercetin (3-MeQ), as a part of materials standardization for the development of health functional foods from stems of Opuntia ficus-indica var. saboten (OFS). The quantitative determination method of marker compounds was optimized by HPLC analysis, and the correlation coefficient for the calibration curve showed very good linearity. The HPLC-PDA method was applied successfully to quantification of marker compounds in OFS after validation of the method in terms of linearity, accuracy, and precision. Ethanolic extracts from stems of O. ficus-indica var. saboten (OFSEs) were evaluated by reflux extraction at 70 and $80^{\circ}C$ with 50, 70, and 80% ethanol for 3, 4, 5, and 6 h. Among OFSEs, OFS70E at $80^{\circ}C$ showed the highest contents of DHK and 3-MeQ of $26.42{\pm}0.65$ and $3.88{\pm}0.29mg/OFS100g$, respectively. Furthermore, OFSEs were determined for their antioxidant activities by measuring 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging and lipid peroxidation (LPO) inhibitory activities in rat liver homogenate. OFS70E at $70^{\circ}C$ showed the most potent antioxidant activities with $IC_{50}$ values of $1.19{\pm}0.11$ and $0.89{\pm}0.09mg/mL$ in the DPPH radical scavenging and LPO inhibitory assays, respectively. To identify active components of OFS, various chromatographic separation of OFS70E led to isolation of 11 flavonoids: dihydrokaempferol, dihydroquercetin, 3-O-methylquercetin, quercetin, isorhamnetin 3-O-glucoside, isorhamnetin 3-O-galactoside, narcissin, kaempferol 7-O-glucoside, quercetin 3-O-galactoside, isorhamnetin, and kaempferol 3-O-rutinoside. The results suggest that standardization of DHK in OFSEs using HPLC-PDA analysis would be an acceptable method for the development of health functional foods.

• Analytical Science and Technology
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• v.23 no.6
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• pp.531-536
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• 2010

A quantitative analytical method has been established for the measurement of inosine 5'-monophosphate dehydrogenase (IMPDH) activity in human peripheral blood mononuclear cells (PBMCs) by ion-pair reversed-phase high performance liquid chromatography equipped with ultraviolet detection (HPLC/UV). IMPDH is a ${\beta}$-nicotinamide adenine dinucleotide hydrate (NAD+)-dependent dehydrogenase in which the enzyme converts inosine 5'-monophosphate (IMP) into xanthosine 5'-monophosphate (XMP). Its activity was measured by quantifying a HPLC chromatogram corresponding to XMP produced during the incubation of lysed PBMCs with IMP as a substrate and $NAD^+$ as a coenzyme. XMP produced was detected at a wavelength of 260 nm. The mobile phase was composed of a mixture of 37 mM potassium dihydrogen phosphate containing 7 mM tetra-n-butylammonium hydrogen sulfate adjusted to pH 5.5 and methanol (85:15, v/v) with a flow rate of 1 mL/min. The calibration curve was linear ($r^2$=0.999999) in the range of $0.2-50.0\;{\mu}M$ and the limit of quantification (LOQ) was $0.2\;{\mu}M$. The intra- and inter-day precisions were between 0.88-1.47% and 0.85-5.24%, respectively. The intra- and inter-day accuracies were between 98.74-99.99% and 99.95-101.65%, respectively. IMPDH activity in 11 Korean healthy volunteers ranged from 18.29 to 36.60 nmol/h/mg protein (mean = $27.70{\pm}6.28\;nmol/h/mg$ protein).

• Journal of the Korean Society of Food Science and Nutrition
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• v.45 no.11
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• pp.1610-1616
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• 2016

This study aimed to establish an optimal extraction process and high performance liquid chromatography-ultraviolet (HPLC-UV) analytical method for determination of 3,5-dicaffeoylquinic acid (3,5-DCQA) as a part of materials standardization for the development of a xanthine oxidase inhibitor as a health functional food. The quantitative determination method of 3,5-DCQA as a marker compound was optimized by HPLC analysis using a Luna RP-18 column, and the correlation coefficient for the calibration curve showed good linearity of more than 0.9999 using a gradient eluent of water (1% acetic acid) and methanol as the mobile phase at a flow rate of 1.0 mL/min and a detection wavelength of 320 nm. The HPLC-UV method was applied successfully to quantification of the marker compound (3,5-DCQA) in Aster glehni extracts after validation of the method with linearity, accuracy, and precision. Ethanolic extracts of A. glehni (AGEs) were evaluated by reflux extraction at 70 and $80^{\circ}C$ with 30, 50, 70, and 80% ethanol for 3, 4, 5, and 6 h, respectively. Among AGEs, 70% AGE at $70^{\circ}C$ showed the highest content of 3,5-DCQA of $52.59{\pm}3.45mg/100g$ A. glehni. Furthermore, AGEs were analyzed for their inhibitory activities on uric acid production by the xanthine/xanthine oxidase system. The 70% AGE at $70^{\circ}C$ showed the most potent inhibitory activity with $IC_{50}$ values of $77.01{\pm}3.13{\sim}89.96{\pm}3.08{\mu}g/mL$. The results suggest that standardization of 3,5-DCQA in AGEs using HPLC-UV analysis would be an acceptable method for the development of health functional foods.