• KOREAN JOURNAL OF CROP SCIENCE
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• v.52 no.3
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• pp.303-310
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• 2007

Sweetpotato shoot tops (leaves, tips and petioles) are known to be very useful parts as vegetables because of their high nutritive values and great biomass yield. In this study, the phenolic compound contents, antibacterial activity, mutagenic activity, and antimutagenic activity were investigated in sweetpotato tips that were 10-15cm of shoot top including stems, petioles and tender leaves after sprout of storage roots. The study was done by extracting sweetpotato tips with 80% ethanol and the ethanol fraction was re-extracted with hexane, chloroform, ethyl acetate, butanol and water. In ethyl acetate and butanol fractions, total phenolic compounds contained 95. 6mg/g extract and 69.3 mg/g extract, respectively, The antibacterial activity was measured using the paper disk method with concentrations of 1, 2, 5 and 10 mg/disk of butanol and ethyl acetate fractions against L. monocytogenes and S. Typhimurium strains. Higher doses of solvent extracts showed the higher antibacterial activities. In addition, 5, 10 and 20 mg/mL of the extracts were tested to determine the antibacterial activity in liquid culture. The sweetpotato leaf extract by ethyl acetate showed 1 log reduction compared to control after 24 hrs on Listeria monocytogenes, but 20 mg/ml of butanol extract completely inhibited the growth of the pathogen after 12 hrs. The extracts from ethyl acetate or butanol on Salmonella Typhimurium did less than 1 log reduction during cultivation compared to control. The numbers of S. Typhimirium TA98 and TA100 revertant colonies were 29-33 and 159-188 CFU/plate, respectively, indicating that solvent extracts were no mutagenic activity. The antimutagenic test was performed by adding direct mutagen 2-NF and MMS, and butanol and ethyl acetate showed antimutagenic effect. Thus, this study showed that sweetpotato tips had high phenolic contents and both antimicrobiol and antimutagenic properties. Sweetpotato tips would be good nutritive source because of their high nutrient content without any toxicity in consuming.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.55 no.1
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• pp.24-30
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• 2010

Comprehensive studies on seedling production and transplanting cultivation of waxy corn are necessary to fulfill the comsumer's preference for the high quality whole ear waxy corn and its year-round supply for higher price, and to escape marketing in a short period at harvest season. Two waxy corn hybrids (cv. Chalok# 1 and Chalok# 4) were used to study the effects of seeding date, nursery days and plug cell size on growth and yield of waxy corn, and to clarify the reliable transplanting date at the Experimental Field of the National Institute of Crop Science in 2007. The number of days from seeding to silking was increased as nursery days were extended, but the number of days from transplanting to silking was shortened comparing to the direct seeding. Number of days from seeding to silking was shorter by 9~12 days for Chalok# 1 than for Chalok# 4, while the number of days from seeding to silking was shorter by 12~15 days in the second cropping than in the first cropping. Culm length of transplanted waxy corns was decreased as the nursery days were extended. Culm length of seeded Chaok# 1 and Chaok# 4 were decreased by 17% and 24%, respectively, in the second cropping compared to those in the first cropping. Ear length was somewhat decreased as the nursery days were extended. Chalok# 1 in the second cropping the degree of decrease was much higher in second cropping than in first cropping of Chalok# 1. Comparing to the first cropping, number of marketable ears per 10a of Chalok# 1 decreased as high as 64%, while that of seeded Chalok# 4 decreased mere 12% in the second cropping.

• Korean Journal of Ecology and Environment
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• v.50 no.1
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• pp.79-95
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• 2017

Euiam and Paldang Reservoirs have often been facing water quality problems, such as eutrophication, algal blooms and off-flavors by treated wastewater effluent (TWE) in the North-Han and the Han River basins, but little is examined on the direct biological effect of TWE. This study tested algal growth potential (AGP) of four TWEs discharged into Euiam and Paldang Reservoirs to evaluate water fertility in September 2014 and March and September 2015. Test alga was used Anabaena circinalis isolated from Paldang Reservoir. Mean concentration of T-N and T-P in TWEs was $3,956.7{\mu}g\;N\;L^{-1}$ and $50.8{\mu}g\;P\;L^{-1}$, and the proportion of $NO_3-N$ and $PO_4-P$ to the total fraction was 72.1% and 40.8%, respectively. Both N and P were high in TWEs, but much higher N than P concentration indicates strong P-limitation. As a consequence, the maximum AGP was determined by $PO_4-P$ concentration (r=0.998, p<0.01). Mean AGP value was $15.4mg\;dw\;L^{-1}$ among four effluents indicating its eutrophic condition. Due to the establishment of tertiary (advanced T-P) treatment method in the studied plants recently, P concentration was significantly decreased in TWEs compared to the years prior to 2012. However, P concentration seems to be still high enough to cause eutrophication and algal blooms. Therefore, wastewater treatment to P-free level needs to be considered if effluents are directly discharged into the drinking water resources.

• Journal of Biomedical Engineering Research
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• v.23 no.1
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• pp.9-16
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• 2002

Localized muscle fatigue can be identified by a downward shift of the EMG frequency typically represented by a fall in the median frequency The Present experimental study was Performed to investigate the time change of the median frequency and the muscle torque during maximal isometric back extension exercises at different exercise angles (0$^{\circ}$, 12$^{\circ}$, 36$^{\circ}$and 72$^{\circ}$) Twenty heath subjects (mean age : 24.35 $\pm$ 2.70) were Participated in this study Median frequency was extracted from EMG signals by employing the fast Fourier transform. Initial median frequency and the slope of median frequency was not significantly correlated with the muscle torque. Pearson's Product moment correlation was used to quantify the relationship between slopes of median frequency and torque. The results may suggest that the exorcise angle during maximal isometric back extension exercises does not affect the slopes of the median frequency and torque, and y-intercept of the median frequency among exercise angles There was no significant correlation between slopes of median frequency and torque. But there was a moderate correlation between median frequency and torque at each exercise angle. In conclusion, the exercise angle during maximal isometric back extension exercise is not a direct effect on slopes of median frequency and torque. But results showed that the shift of median frequency and torque shift were highly correlated in all subjects.

• Korean Journal of Food Science and Technology
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• v.3 no.3
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• pp.178-184
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• 1971

Samples of refined soybean oil were irradiated with lights from a 20-watt incandescent tungsten lamp, a 20-watt fluorescent daylight type lamp, a 20-watt low-pressure mercury vapor germicidal lamp, and direct sunlight for an experimental period of 147 days. Some samples were stored in a dark room throughout the period as a control. The peroxide values of all samples were measured every week. The induction period of the samples was arbitrarily taken as the time required for the samples to reach a peroxide value of 15. The induction period of the control was estimated at 198 days. Those of the samples irradiated with the incandescent light, the fluorescent light, the ultraviolet light, and the sunlight were estimated at 196, 119, 52 and 6 days, respectively. The sunlight showed by far the strongest prooxidant activity whereas the incandescent light showed the weakest but distinct prooxidant activity. The small temperature differences observed among the various samples throughout the experimental period did not seem to affect the oxidation rates of the irradiated samples in any significant way.

• Tuberculosis and Respiratory Diseases
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• v.39 no.4
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• pp.334-342
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• 1992

Background: The activated T lymphocyte by inhalaed mycobacterial antigen may evoke cell-mediated immunity in patients with active pulmonary tuberculosis. These activated lymphocyte may influence the response of tuberculin-purified protein derivative (PPD) in skin test. But occasionally, anergy to PPD appear in patients with pulmonary tuberculosis in spite of active stage. Thus we evaluated the effect of change of subtypes of lymphocyte in bronchoalveolar lavage fluid (BAL) and peripheral blood on anergy to PPD in patients with active pulmonary tuberculosis. Method: We performed tuberculin skin test and flow-cytometry analysis of lymphocytes obtained from BAL fluid and peripheral blood in 11 healthy normal volunteers and 20 patients with active pulmonary tuberculosis. Results: 1) The composition of lymphocyte significantly increased in patients with active pulmonary tuberculosis when compared with that in healthy control ($25.2{\pm}4.8$ vs $6.5{\pm}1.3%$, p<0.01), but composition of monocyte significantly decreased ($69.6{\pm}5.7$ vs $89.2{\pm}1.4%$, p<0.05) in analysis of BAL fluid. 2) There were no differences in compositions of cells in BAL fluid between responders and no-responders to PPD. 3) The compositions of CD3 (+), CD4 (+), CD3 (+) IL-2R (+), CD3 (+) HLA-DR (+) significantly increased in BAL fluid when compared with those in peripheral blood in patients with active pulmonary tuberculosis. But the composition of CDS (+), CD4/CDS were not different between BAL fluid and peripheral blood. 4) There were no correlations between response to PPD and compositions of cells and lymphocyte subtypes in BAL fluid and peripheral blood in all patients with tuberculosis, responders, and no-responders, respectively. Conclusion: From these results, we suggest no direct relationship between compositions of inflammatory cells in bronchoalveolar lavage fluid and we could not rule out the possibility of compartmentalization of activated lymphocyte involving in anergy to PPD in skin test in patients with active pulmonary tuberculosis.

• Korean Journal of Agricultural Science
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• v.13 no.2
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• pp.219-226
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• 1986

A study was conducted to provide direct comparisons of the effect of variations in herbage use, grazing and social behaviour upon the flat, slope and forest grassland with a total 30 Korean Native Cattle and 5 Korean Native Goats under 4-year old grassland established by intensive sowing method in Daecheon. The results obtained are summarized as follows; 1. Relative intake index, dry matter intake per animal and dry matter digestibility by Korean Native Goats in flat, slope and forest grassland were 35.2%-462g-63.7%, 35.0%-459g-63.0% and 29.8%-391g-62.1%, respectively. 2. Grazing time by Korean Native Cattle was not different among the grassland types, but ruminating time was increased in slope grassland, whereas in forest grassland was decreased. Resting time was increased in forest grassland, whereas in slope grassland was decreased. Walking time was increased in flat grassland, but loafing time was increased in forest grassland. The number of rumination, chews per bolus and defecation number were decreased in forest grassland. The number of drinks, total drinking water and walking distance were increased in slope grassland. 3. Animal distance, occupied area per animal and sub group formation by Korean Native Cattle in flat, slope and forest grassland were $3.4m-11.9m^2-3.6head$, $3.56m-11.0m^2-3.7head$ and $3.70m-14.6m^2-3.4head$, respectively. The order of grazing movement was similar to the pear-shaped grazing formation, but the relations of dominance between first grazer and last grazer upon different grassland types was not clear.

• Korean Journal of Weed Science
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• v.17 no.4
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• pp.439-444
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• 1997

The causes of late establishment of barnyardgrass and their density effect on rice yield loss were examined in 1996 and 1977. Herbicide application on 5 to 15DAT(Days after transplanting) increased from 6% to 52.5%, 1988 to 1992, and their ingredient amount for barnyardgrass control decreased to 41.7-87.5% in Korea. Most late establishment of barnyardgrass in machine transplanted rice field were not late germinated but revived ones. The number of late established barnyardgrass were 0.5, 2.0 and 13.3/$m^2$, on direct seeded at May 10, and machine transplanted May 23 and June 9, individually. Relation on rice yield and the number of barnyardgrass at machine transplanted field showed highly significant equation, as y=543.3 4.7x, r=0.9039 in 1996 and y=515.8 10.4x+0.066$x^2$, $R^2$=0.9532 in 1997. Theoritical yield loss by regress equation showed 2% per one plant of barnyardgrass per $m^2$ and 5, 10, 20, 50, and 80 plants of barnyardgrass decreased rice to 10, 19, 35, 69 and 79%, individually.

• Hwankyungkyoyuk
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• v.6 no.1
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• pp.63-99
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• 1994

The international environmental activities and environmental education began in 1970's. Environmental education in Korea was emphasized since the Forth National Curriculum. 'The Environmental Education Curriculum' will be separated as one of the most important parts in the Sixth National Education Curriculum in Korea. The purpose of this study was development. of 'Environmental Science' of high school appropriate to Sixth National Education Curriculum. First step was to state goals of environmental education in detail based on analysis of goals about environmental education in our country and other countries. Second was to analyse seven environments-related texts of Korea, America and England. Third, to measure how much environmental education has achieved in Fifth National Curriculum of Korea. Fourth, to develop a new environmental text of high school level. Fifth, to verify the effect of developed environmental text. The environmental part of 'Science I'(unit V. Life and Environments) and high school environments-related reference text(Survival and Environments) in Korea, American knowledges. American 'Environments' was stressed in many skills but they didn't include various teaching strategies. On the other hand, American 'Science-Technology-Society(S-T-S)' and British 'Science and Technology in Society(SATIS)' were stressed in knowledges and skills, and they included many teaching strategies and student actions. American 'S-T-S' was the only one stressed in values and attitudes. And all seven texts were not interested in behaviors and participations. To measure the achievement of environmental education by questionnaire, 497 high school students in total were selected from five different schools. Actually, most students had a positive thinkings and attitudes in their hearts about environmental problems, about environmental problems, but many of them did not take actions to solve environmental problems and to protect environments. The higher the score students got in 'knowledges and informations', the higher the score in 'skill'. It implies that learning of skills is based on learning of knowledges and informations about environments. On the other hand, much knowledges and information about environments has not always ensured positive thinkings and attitudes or active behaviors and participations to solve environmental problem. In view that ultimate aim of environmental education is forming responsible environmental behaviors and the goals of values and behaviors are as important as knowledges and skills. A new environmental text of high school level was developed and it was based on analysis of seven texts and environmental education in Fifth Korean Curriculum. This text have seven units, 1. Habitates : What're the meanings?, 2. Nuclear Energy : Can't be Avoid?, 3. Acid Rain : What're the Messages?, 4. Ethanol : Is this Future Fuel?, 5. Wastes : A New War!, 6. What're the National and Gloval Environmental education and avoided from the array of knowledges. Therefore included various teaching strategies and independent actions of students. 'Open-ended value learning' and 'free behavior learning' in text were special learning parts for aquisition of values and formation of behaviors. To verify the effects. of new developed environmental text, the direct learning was carried out by 286 students in total. Post test scores of experimental groups per each units were significantly higher than those of control groups from five different schools were as follows. For validity of selecting contents for units, 74% of respondent replied positively. For classification and presentation of four goal-groups, 90% replied positively in validity and 82%, in utility. For validity of various teaching strategies, 88% and for the degree of including student-centered independent actions, 86% replied positively, For importances and expected effects of 'open=ended value learning' and 'free behavior learning', showed positive responses respectively, 88%, 92% Therefore this text is effective to achieve four goals of environmental education equally.

• Journal of Korea Water Resources Association
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• v.46 no.6
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• pp.597-611
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• 2013

This paper presents the methodology for construction of time-area curve via the width function and thereby rational estimation of time of concentration and storage coefficient of Clark model within the framework of method of moments. To this end time-area curve is built by rescaling the grid-based width function under the assumption of pure translation and then the analytical expressions for two parameters of Clark model are proposed in terms of method of moments. The methodology in this study based on the analytical expressions mentioned before is compared with both (1) the traditional optimization method of Clark model provided by HEC-1 in which the symmetric time-area curve is used and the difference between observed and simulated hydrographs is minimized (2) and the same optimization method but replacing time-area curve with rescaled width function in respect of peak discharge and time to peak of simulated direct runoff hydrographs and their efficiency coefficient relative to the observed ones. The following points are worth of emphasizing: (1) The optimization method by HEC-1 with rescaled width function among others results in the parameters well reflecting the observed runoff hydrograph with respect to peak discharge coordinates and coefficient of efficiency; (2) For the better application of Clark model it is recommended to use the time-area curve capable of accounting for irregular drainage structure of a river basin such as rescaled width function instead of symmetric time-area curve by HEC-1; (3) Moment-based methodology with rescaled width function developed in this study also gives rise to satisfactory simulation results in terms of peak discharge coordinates and coefficient of efficiency. Especially the mean velocities estimated from this method, characterizing the translation effect of time-area curve, are well consistent with the field surveying results for the points of interest in this study; (4) It is confirmed that the moment-based methodology could be an effective tool for quantitative assessment of translation and storage effects of natural river basin; (5) The runoff hydrographs simulated by the moment-based methodology tend to be more right skewed relative to the observed ones and have lower peaks. It is inferred that this is due to consideration of only one mean velocity in the parameter estimation. Further research is required to combine the hydrodynamic heterogeneity between hillslope and channel network into the construction of time-area curve.