• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.8 no.1
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• pp.44-57
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• 2003

Seasonal variations of bacterial abundance and production, heterotrophic nanoflagellate (HNF) abundance and HNF ingestion rates on bacteria using FLB together with environmental variables were investigated at intervals of a month in Kyeonggi Bay from December 1991 to November 1998. Bacterial abundance and production ranged from 0.38$\times$10$^{9}$ ~ 3.25$\times$10$^{9}$ cells 1$^{-1}$ (average 1.19$\pm$0.69$\times$10$^{9}$ cells 1$^{-1}$ ) and from 1.51 to 20.4 cells 1$^{-1}$ h$^{-1}$ (average 6.04$\pm$ 1.88$\times$10$^{6}$ cells 1$^{-1}$ h$^{-1}$ ), respectively. Bacterial abundance and production showed no differences at the high tide and low tide, and bacterial abundances were not different with depth, but bacterial production decreased with depth. Seasonal variation of bacterial abundance showed almost similar fluctuation pattern to those of DOC (dissolved organic carbon). HNF abundances ranged from 388 to 4,374 cells ml$^{-1}$ (average 1,344$\pm$130 cells ml$^{-1}$ ), were high in March, April, July and August. HNF abundance showed no difference between the high tide and low tide, and was not different with depth. The ingestion rates of HNF on bacteria were 1.0 to 6.3$\pm$10$^{6}$ bacteria 1$^{-1}$ h$^{-1}$ (average 3.12$\pm$0.55$\times$10$^{6}$ bacteria 1$^{-1}$ h$^{-1}$ ), resulting ingestion rates of HNF removed 19.4 to 141.4 %(average 62.3$\pm$12.0%) of bacterial production. Ingestion rates and grazing pressure of HNF on bacteria showed high correlation with HNF abundance. Although we cannot exactly discussion about seasonal variation of bacteria community in this study area where physical and chemical parameters were very complex, the results indicate that bacterial abundance and production were mainly controlled by resources supply as dissolved organic carbon and chlorophyll-a(bottom-up) except March which bacterial abundance and production uncoupled chlorophyll-a because of low dissolved organic carbon and low temperature, and were controlled by HNF grazing pressure(top-down) in the warm seasons except the winter.

• Journal of Mushroom
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• v.10 no.4
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• pp.216-223
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• 2012

Oyster mushroom is one of the popular mushrooms for Korean people and it is thus one of the mushrooms that were mostly cultivated in Korea in addition to winter and king oyster mushrooms. To promote the consumption in terms of its nutritional value and determine the absorption mechanism in its physiological and metabolic aspects, we investigated the sugar composition of its fruit bodies according to the amount of sugar component in the medium. As a result from the treatment of 4 different sugar components to the sawdust medium of oyster mushroom varieties (i.g., Suhan 1 ho, Yeorum, Chunchu 2 ho), we detected fructose, glucose, ribose, xylose as a monosaccharide with ${\alpha}$-lactose and trehalose as a disaccharide. The sugar alcohols were also detected including glycerol, mannitol, myo-inositol, and sorbitol. The sugar components that were detected in all treatments were trehalose, mannitol, ${\alpha}$-lactose, fructose, glucose, ribose, and myo-inositol and the rest of the components were found in some treatments with their different quantity included in the fruit bodies. The amount of monosaccharides included in fruit bodies is comparatively low and Suhan 1 ho contained them more than other varieties. There was no remarkable difference in the amount of sugar components in fruit bodies depending on treated sugars and their amounts in the treatment. With the increase of lactose treatment, the sugar components were markedly increased and the amount of trehalose in the fruit bodies was different according to the varieties. Therefore, it is not possible to detect the trend of sugar components according to the medium used in the cultivation. The sugar alcohols in the fruit bodies were comparatively contained more in Suhan 1 ho and Chunchu 1 ho. The amount of mannitol in the fruit bodies was not possible to be detected in terms of its trend according to the treatment. For myo-inositol, its quantity is gradually increasing in Suhan 1 ho and Chunchu 1 ho and it is not possible to detent the trend in Yeorum. In conclusion, we only detected ${\alpha}$-lactose as a sugar component that showed a correlation between the amount of treatment and the amount of the fruit bodies. Therefore, the sugar components detected in the fruit bodies were transformed rather than direct absorption into fruit bodies and further studies are needed to address this question.

• Magazine of the Korean Society of Agricultural Engineers
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• v.19 no.1
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• pp.4279-4295
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• 1977

Two types of model were established in order to product the soil moisture content by which information on irrigation could be obtained. Model-I was to represent the soil moisture depletion and was established based on the concept of water balance in a given soil profile. Model-II was a mathematical model derived from the analysis of soil moisture variation curves which were drawn from the observed data. In establishing the Model-I, the method and procedure to estimate parameters for the determination of the variables such as evapotranspirations, effective rainfalls, and drainage amounts were discussed. Empirical equations representing soil moisture variation curves were derived from the observed data as the Model-II. The procedure for forecasting timing and amounts of irrigation under the given soil moisture content was discussed. The established models were checked by comparing the observed data with those predicted by the model. Obtained results are summarized as follows: 1. As a water balance model of a given soil profile, the soil moisture depletion D, could be represented as the equation(2). 2. Among the various empirical formulae for potential evapotranspiration (Etp), Penman's formula was best fit to the data observed with the evaporation pans and tanks in Suweon area. High degree of positive correlation between Penman's predicted data and observed data with a large evaporation pan was confirmed. and the regression enquation was Y=0.7436X+17.2918, where Y represents evaporation rate from large evaporation pan, in mm/10days, and X represents potential evapotranspiration rate estimated by use of Penman's formula. 3. Evapotranspiration, Et, could be estimated from the potential evapotranspiration, Etp, by introducing the consumptive use coefficient, Kc, which was repre sensed by the following relationship: Kc=Kco$.$Ka＋Ks‥‥‥(Eq. 6) where Kco : crop coefficient Ka : coefficient depending on the soil moisture content Ks : correction coefficient a. Crop coefficient. Kco. Crop coefficients of barley, bean, and wheat for each growth stage were found to be dependent on the crop. b. Coefficient depending on the soil moisture content, Ka. The values of Ka for clay loam, sandy loam, and loamy sand revealed a similar tendency to those of Pierce type. c. Correction coefficent, Ks. Following relationships were established to estimate Ks values: Ks=Kc-Kco$.$Ka, where Ks=0 if Kc,=Kco$.$K0$\geq$1.0, otherwise Ks=1-Kco$.$Ka 4. Effective rainfall, Re, was estimated by using following relationships : Re=D, if R-D$\geq$0, otherwise, Re=R 5. The difference between rainfall, R, and the soil moisture depletion D, was taken as drainage amount, Wd. {{{{D= SUM from { {i }=1} to n (Et-Re-I+Wd)}}}} if Wd=0, otherwise, {{{{D= SUM from { {i }=tf} to n (Et-Re-I+Wd)}}}} where tf=2∼3 days. 6. The curves and their corresponding empirical equations for the variation of soil moisture depending on the soil types, soil depths are shown on Fig. 8 (a,b.c,d). The general mathematical model on soil moisture variation depending on seasons, weather, and soil types were as follow: {{{{SMC= SUM ( { C}_{i }Exp( { - lambda }_{i } { t}_{i } )+ { Re}_{i } - { Excess}_{i } )}}}} where SMC : soil moisture content C : constant depending on an initial soil moisture content $\lambda$ : constant depending on season t : time Re : effective rainfall Excess : drainage and excess soil moisture other than drainage. The values of $\lambda$ are shown on Table 1. 7. The timing and amount of irrigation could be predicted by the equation (9-a) and (9-b,c), respectively. 8. Under the given conditions, the model for scheduling irrigation was completed. Fig. 9 show computer flow charts of the model. a. To estimate a potential evapotranspiration, Penman's equation was used if a complete observed meteorological data were available, and Jensen-Haise's equation was used if a forecasted meteorological data were available, However none of the observed or forecasted data were available, the equation (15) was used. b. As an input time data, a crop carlender was used, which was made based on the time when the growth stage of the crop shows it's maximum effective leaf coverage. 9. For the purpose of validation of the models, observed data of soil moiture content under various conditions from May, 1975 to July, 1975 were compared to the data predicted by Model-I and Model-II. Model-I shows the relative error of 4.6 to 14.3 percent which is an acceptable range of error in view of engineering purpose. Model-II shows 3 to 16.7 percent of relative error which is a little larger than the one from the Model-I. 10. Comparing two models, the followings are concluded: Model-I established on the theoretical background can predict with a satisfiable reliability far practical use provided that forecasted meteorological data are available. On the other hand, Model-II was superior to Model-I in it's simplicity, but it needs long period and wide scope of observed data to predict acceptable soil moisture content. Further studies are needed on the Model-II to make it acceptable in practical use.

• Korean Journal of Agricultural and Forest Meteorology
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• v.8 no.3
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• pp.183-189
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• 2006

Six japonica and three Tongil type cultivars that were released in different years and planted to a large area during different periods were grown at the experimental farm of Seoul National University in 2001 and compared for traits related to dry matter production and grain yield. The varieties chosen were Jodongji released in 1896, Paldal in 1944, Jinheung in 1962, Nagdong and Tongil (Tonsil type) in 1971, Milyang#23 (Tongil type) in 1976, Hwasung in 1986, Ilpum in 1991, and Dasan (Tonsil type) in 1996. The more recent cultivars tended to have lower canopy light extinction coefficients (K). The K value was 0.601 in the oldest cultivar, Jodongji, and decreased below 0.5 in the cultivars released since 1971. Radiation use efficiency (RUE) was significantly different among cultivars before heading stage, showing no consistent tendency with the year of release and not significantly different after heading. Leaf area duration (LAD) was significantly different among varieties, and LAD values tended to be higher in the more recent cultivars. In particular, this tendency was more obscure in Tongil type cultivars. LAD of whole growth period had a significantly positive correlation with dry matter yield at harvest $(r=0.776^*)$. Dry matters measured at heading and harvest tended to be higher in recently released cultivars, but not significantly. The grain yield of Jodongji was the lowest but there was no significant difference among the other varieties in japonica, while higher yield occurred in the more recent Tongil type. Grain yield was correlated with grain number per square meter, and the more recent Tongil type cultivars had the greater grain number per square meter, In conclusion, not only the dry matter and grain yield but also related traits except K value showed no clear changes when compared with the year of their release in japonica cultivars. However, the increased grain yield in the more recent Tonsil type cultivars might have resulted from the enhanced LAD that lead to the higher dry matter production and in turn to the enlarged sink size.

• Korean Journal of Environmental Agriculture
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• v.36 no.2
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• pp.113-118
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• 2017

BACKGROUND: The carbon (C) isotope ratio (${\delta}^{13}C$) of dissolved organic C (DOC) is an indicator of water pollution source. In this study, the potential use of two pre-treatments for the ${\delta}^{13}C$ analysis, alkaline persulfate oxidation coupled with carbonate precipitation (precipitation) and freeze drying (drying), were compared to suggest a more feasible pre-treatment method. METHODS AND RESULTS: Two reference materials with different ${\delta}^{13}C$ values were used for the experiments; chemical grade glucose ($-12.0{\pm}0.02$‰) and pig manure compost extract ($-23.3{\pm}0.04$‰). In the precipitation method, the measured ${\delta}^{13}C$ values were consistently lower than the theoretically calculated values as dissolved $CO_2$ could not be removed due to the alkaline property of the reagents and the dissolution of air $CO_2$ into the alkaline solution. The drying method also resulted in more negative ${\delta}^{13}C$ than the calculated ${\delta}^{13}C$; however, the difference was systematic ($3.9{\pm}0.3$‰) and there was a strong correlation (${\delta}^{13}C_{calculated}=0.87{\times}{\delta}^{13}C_{measured}-0.624$, $r^2=0.98$) between the calculated and measured ${\delta}^{13}C$. Calibration of ${\delta}^{13}C$ using the relationship between the calculated and the measured ${\delta}^{13}C$ values produced reliable and accurate ${\delta}^{13}C$ values. CONCLUSION: Our results suggest that the drying method is more accurate pre-treatment method to minimize the influence of air $CO_2$ compared to the precipitation method for the determination of ${\delta}^{13}C$ of DOC.

• Journal of The Korean Society of Grassland and Forage Science
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• v.9 no.1
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• pp.7-14
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• 1989

This experiment was carried out to determine the seasonal herbage production and utilization during the growing season of pasture on the forest (shading 30%). Plant height, leaf area index(LAl), dry matter(DM) production and distribution, chemical composition, in vitro dry matter digestibility(IVDMD), herbage utilization percentage and chewing efficiency were investigated using the Corridale sheep. Experimental field was treated by one plot design(3 rep.) and performed from 1987 to 1988 at Chungnam National University, Daejon. The results obtained are summarized as follows: 1. The highest plant height and LA1 were observed in May(35.0 cm, 4.89), followed by April(28.0 cm, 4.23), while the plant height and LA1 in October (13.0 cm, 0.49) showed very low. 2. During the growing season, about 58.3 % of annual DM production (7240 kg/ha) was produced during the spring (April, May and June) and the highest DM production was obtained in May (2040 kg/ha), which was more than 28.2 % of total DM production. However, DM production in July and August was about 24.2 % and those in September and October (17.5 %) was very low, but the difference of DM production from June to September was small. 3. The maximum DM production per day (65.8 kg/ha) was observed in May, followed by June (28.7 kglha), while DM production per day in October (16.5 kg/ha) showed very low (p <0.01). 4. Crude protein content and IVDMD of herbage samples during the spring (April, May and June) were higher, while crude fiber, ADF, and NDF content were lower in an summer growth herbage samples (July and August), but autumn growth herbage samples was intermediate. Crude ash content and IVDMD of collected herbage samples were slightly more, while crude fiber, ADF and NDF content were slightly less than offered and residued herbage samples during the growing season. 5. The maximum DM intake per metabolic body size was observed in May(68.9 g), followed by October (66.7 g), while very low in August (52.5 g). Significant positive correlation (p <0.05) was found between DM intake and IVDMD. 6. Herbage utilization percentage was very high in April (83.4 %), while very low in August (64.0 %). The percentage of annual herbage utilization was about 75.5 %. 7. The maximum ruminating and chewing efficiency of herbage samples were observed in May, followed by October, while very low in August.

• Korean Journal of Food Science and Technology
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• v.42 no.1
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• pp.33-38
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• 2010

This study was conducted to compare the physicochemical properties of powdered green teas produced in Korea and Japan including particle size, color, chlorophyll, caffeine and theanine. The average particle size of Korean powered green tea ($14.63-25.39\;{\mu}m$) was similar to that of Japanese powdered green tea ($15.46-21.02\;{\mu}m$). The surface color of shade-cultivated Haenam Green Tea (HN-1) had the highest negative 'a' value, which represents 'green' color. When the TCD (total color difference value) was measured in the samples, HN-1 was most similar to the premium powdered green tea of Japan (JA-1). Domestic shade-cultivated powdered green teas had 1.5-2 times greater chlorophyll content than powdered green teas produced from plants that were not cultivated in the shade. The presence of chlorophyll a resulted in a higher intensity of green color than the presence of chlorophyll b. A significant negative correlation was also observed between the color and the chlorophyll a, chlorophyll b and total chlorophyll contents. Specifically, chlorophyll a had the greatest impact on the green color of powdered green tea. The content of catechins, caffeine and theanine in Korean powdered green teas ranged from 14.679-20.128, 1.496-3.237 and 0.926-1.977 g/100 g, respectively. The caffeine and theanine contents were high in shade-cultivated powdered green teas. Based on the above results, domestic powdered green teas cultivated under shaded conditions had a quality similar to that of medium-quality green teas produced in Japan, and the overall quality of Korean powdered green tea was poorer than that of Japanese powdered green tea.

• Journal of The Korean Society of Grassland and Forage Science
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• v.19 no.3
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• pp.211-220
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• 1999

The corn is mostly planted in mid-April in single-cropping silage system if possible, however, in a double-cropping silage system, the corn planting date is delayed until after the mid-May. The objective of this study was to evaluate agronomic characteristics and forage performance of the eight government recommended corn hybrids for silage at two dates of planting. Split-plot design replicated three times was used, that is, main plots were planting dates, sub-plots were eight hybrids at Suweon in 1997. Days from planting to silking of optimum planting was 84 days and that of late was 69 days. The difference in silking day among the hybrids was 6 days at optimum planting and 2 days at late planting. Plant height of optimum planting corn was higher than that of late one, however, ear height and stem diameter of optimum planting were lower than those of late planting corn. Among the corn hybrids tested, plant heights of 'P3156' and 'P3163' were higher than those of the other hybrids. Ear height of 'DK713' was the lowest among the corn hybrids and stem diameter of 'P3394' was thicker than that of the other hybrids. European corn borer(ECB) damage(16.6%) at optimum planting was lower than that(49.9%) of late, however, there were no significant ECB damage differences among the corn hybrids tested. Whole plant dry matter(DM) contents of 'P3525', 'P3394' and 'P3352' hybrids were higher than those of the other corn hybrids at harvest. Ear percentages of the total dry matter(DM) of 'P3394' and 'P3156' were higher than those of the other corn hybrids. Dry matter(DM) and total digestible nutrients(TDN) yields(19,696 and 14,621kg/ha) at optimum planting were higher than those (17,163 and 12,570kg/ha) of late planting, while there were no significant differences in DM and TDN yields among the corn hybrids tested. And those hybrids with greater proportion of grain in the whole plant have higher DM and TDN yields. Correlation coefficients for days from planting to silking with DM and TDN yields were $0.84^{**}$ and $0.87^{**}$, and those for ear percent were $0.86^{**}$ and $0.87^{**}$. Results of this study indicate that optimum planting date(15 April) is better than late planting date(16 May) in agronomic characteristics and forage production of silage corn. Days from planting to silking and ear percent as welI as other characters are important factors screening the corn hybrid for silage.

• Korean Journal of Clinical Laboratory Science
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• v.50 no.2
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• pp.144-154
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• 2018

Metabolic disease is associated with abdominal obesity, high blood pressure, and dyslipidemia. Physical activity has beneficial effects on a variety of diseases. This study examined the relationship between metabolic diseases and physical activity according to age. Among a total of 7,295 subjects, the data from 382 individuals in the normal group and 1,525 persons in the metabolic disease group were analyzed. The data were analyzed statistically by one-way ANOVA, the Pearson's correlation coefficient, and multiple regression analysis. The levels of hemoglobin (HB), hematocrit (HCT), and creatinine (CR), were elevated when a high-intensity physical activity was performed, but they were reduced when a low-intensity physical activity was performed in the normal group aged 10~29 years and the metabolic disease group aged 50~69 years. In the normal group and metabolic disease group aged 30~49 years, the level of high density lipoprotein cholesterol (HDL-C) was elevated when high-intensity physical activity was conducted, whereas it was reduced when low-intensity physical activity was performed. No difference in the level of HDL-C depending on age and exercise intensity was observed in the normal group; the level of HDL-C decreased with age and increased with exercise intensity in the metabolic disease group. Physical activity has different effects in metabolic disease depending on age.

• Journal of the Korean Society of Food Science and Nutrition
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• v.43 no.7
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• pp.1062-1067
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• 2014

In the present study, a new analytical method was devised for the simultaneous determination of soluble carbohydrates in soybean seeds using high performance liquid chromatography/evaporative light scattering detection (HPLC/ELSD). The limit of quantification (LOQ) for soybean soluble carbohydrates ranged from 5.6~7.6 mg/kg using the HPLC/ELSD method and from 16.2~33.9 mg/kg using the high performance liquid chromatography/refractive index detection (HPLC/RID) method. Therefore, the HPLC/ELSD method was more sensitive than HPLC/RID. The precision values for retention time and peak area of the HPLC/ELSD method were evaluated by inter-day (n=5) and intra-day (n=10) assays using a standard solution. All precision values (CV<2.5%) for soybean soluble carbohydrates were acceptable and fulfilled international acceptance criteria. All linear calibration curves were obtained with a correlation coefficient of $R^2$ >0.999. The contents of soluble carbohydrates for the "Shingikong" (yellow soybean) and "Cheongjakong 3" (black soybean) samples were analyzed using the HPLC/RID and HPLC/ELSD methods. The difference in carbohydrate contents between the two detection methods was significant. Carbohydrate contents in the HPLC/ELSD method were higher than those in the HPLC/RID method. Overall, the HPLC/ELSD method showed satisfactory resolution with a favorable LOQ and reproducibility. Therefore, these results indicate that the HPLC/ELSD method may be applied to determine the contents of soluble carbohydrates in soybean seeds and related food stuffs.