• Journal of Environmental Impact Assessment
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• v.26 no.6
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• pp.418-430
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• 2017

The quality of surface water is a very important issue to use various demands like as drinking water, industrial, agricultural and recreational usages. There has been an increasing demand for monitoring water quality of many rivers by regular measurements of various water quality variables. However precise and effective monitoring is not enough, if the acquired dataset is not analyzed thoroughly. Therefore, the aim of this study was to estimate differences of seasonal and regional water quality using multivariate data analysis for each investing tributaries in Han River. Statistical analysis was applied to the data concerning 11 mainly parameters (flow, water temperature, pH, EC, DO, BOD, COD, SS, TN, TP and TOC) for the time period 2012~2016 from 12 sampling sites. The seasonal water quality variations showed that each of BOD, TN, TP and TOC average concentration in spring and winter was higher than that of summer and fall, respectively. In summer each flow rate and average concentration of SS was higher than any other seasons, respectively. The correlation analysis were explained that EC had a strong relationship with BOD (r=0.857), COD (r=0.854), TN (r=0.899) and TOC (r=0.910). According to principal component analysis, five principal components (Eigenvalue > 1) are controlled 98.0% of variations in water quality. The first component included TP, DO, pH. The second component included EC, TN. The third component included SS. The fourth component included flow. The last component included Temp. Cluster analysis classified that spring is similar to fall and winter with water quality parameters. AnyA, WangsA, JungrA and TancA were identified as affected by organic pollution. Cluster analysis derived seasonal differences with investigating sites and better explained the principal component analysis results.

• Korean Journal of Ecology and Environment
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• v.44 no.1
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• pp.75-84
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• 2011

We examined the effect of the turbid water on the periphytic diatom community in an artificial stream system. The artificial stream was constructed with transparent acryl and composed of four channels. Each channel ($20\;cm{\times}200\;cm{\times}40\;cm$) was supplied continuously with eutrophic lake water. In order to the freely colonize and grow diatoms, artificial substrate was installed with commercial slide glass soaked in 1% agar. Prior to introducing turbid water, the artificial stream was operated with lake water for 6 days to permit the propagation of diatom community on the substrates. The turbid water prepared with sediment sieved with ${\varphi}$ $64\;{\mu}m$ at $2\;g\;L^{-1}$ (final concentration, 300 NTU) was provided daily for 50 minute duration. The experiment was conducted for 7 days with manipulated experimental condition of light ($50{\sim}80\;{\mu}mol\;m^{-2}s^{-1}$, light:dark=24:0), temperature ($10{\pm}1^{\circ}C$), and flow rate ($0.31\;cm\;s^{-1}$). Sampling and analysis were conducted daily for water quality and diatom. Turbidity of the water varied 162.2~173.2 NTU during the experiment. After introduction of turbid water, DO, pH and TN were decreased, while SS and TP increased significantly. A total of 14 genera and 47 species of diatoms was observed on the artificial substrates during the experimental period. Of these, Navicula appeared to be a most dominant genus with 10 species, followed by Cymbella (6 species), Fragilaria (6 species) and Gomphonema (5 species). Achnanthes minutissima was the most dominant species (>70% of total frequency) in both control and treatment experiments. Increase in diatom abundance lasted for three days since turbid water introduction, after that they gradually decreased by the termination of the experiment. These results suggest that frequent supply of highly-concentrated turbid water significantly decreases the periphytic diatom community, and retard the recovery of the stable food-web within the stream.

• Korean Journal of Ecology and Environment
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• v.41 no.2
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• pp.237-246
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• 2008

Filtration rates and fecal production of freshwater bivalve, Unio douglasiae on two kinds of hibernal diatom communities were measured simultaneously in a laboratory. One community is the Han River (HAN), which dominated by Asterionella Formosa. Stephanodiscus hantzschii (ca. 98% of total phytoplankton). The other community is the Ilgam Lake (IL), which dominated by Synedra ulna, Scenedesmus sp. Microcystis aeruginosa (ca. 82%). The HAN water has higher concentrations of nutrient (TN and TP) and chlorophyll $\alpha$ (Chl-$\alpha$), lower turbidity and conductivity than the IL water. Water sampling for the feeding experiment was conducted in the same day (Jan 15, 2008) and similar time (AM 10:00 for HAN, AM 11:00 for IL). Mussels with the similar size ($0.0{\pm}0.5\;cm$) were collected from the Gunsan and Okgu district (Jeonbuk), and starved in a laboratory for 2 days before the experiment. The experiment comprised CON (no addition of mussel), LOW (addition of mussel at 0.3 indiv. $L^{-1}$), MID (1.0 indiv. $L^{-1}$) and HIGH (2.0 indiv. $L^{-1}$), respectively. With the increment of mussel density and time, the concentration of Chl-$\alpha$ in two diatom communities were clearly decreased; Chl-$\alpha$ of HAN gradually decreased after 1 hour of mussel treatment, while that of IL decreased as soon as mussel introduction. In 7 hours of treatment, the former was removed finally up to about 90% of control, while the later was remained as about 50%. Under the presence of mussel, total phytoplankton density was shifted as the similar patterns to that of Chl-$\alpha$ (r=0.705, P<0.0001), however, there showed the drastic differences following a species. Based on the concentration of Chl-$\alpha$, filtration rate of U. douglasiae averaged 0.266 $L\;g^{-1}\;h^{-1}$ (0.115 to 0.442) on HAN and $0.577\;L\;g^{-1}\;h^{-1}$ (0.146 to 1.428) on IL water, respectively. There were no differences in feces production among the mussel density in the HAH water (ANOVA, P>0.5), while in IL water, including lots of seston, the HIGH mussel produced the higher fecal materials, over one hundred times of LOW. These results suggest that freshwater bivalve Unio douglasiae have the alternative potential, as a filter-feeder of seston in turbid lake, and a biological controller of diatom bloom in cold stream.

• Journal of the korean academy of Pediatric Dentistry
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• v.29 no.2
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• pp.226-236
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• 2002

The purpose of this study was to get descriptive statistics of the contributing factors for early childhood caries and to predict the relationship of dietary, behavior factors and health status factors of the mother and child at pregnancy and after birth. 411 first caregivers of 5-year-old children in 12 kindergartens in Kangnung city were selected by stratified random cluster sampling. They were asked to fill out questionnaires and 364 of them responded. The obtained results were as follow: 1. Over the three-Fourth of children used nursing bottle or had breast feeding habit beyond the age of 1 year. 2. 8.7% of respondents didn't recognize the necessity of the preventive measures immediate after eruption of primary tooth, and only 35.1% replied that they had begun tooth cleaning. 3. Over 90% of children brush the teeth more than once per day. But over half (614%) of them brush their teeth without parents instruction. Sixty percent of children eat between the meals as often as 1-3 time(s) a day and the remainder at any times. 4. The first time of dental visit was for most children (87%) at over 3 years, recommending the earlier dental visit. Notwithstanding the rate of routine dental visit experience was relatively high(40.2%), implicating positive parents' attitude about oral health at Kangnung area. 5. The relationships between oral health state of the parents and the variables such as the timing of the first tooth cleaning, the frequency of brushing, the time of first dental visit, and the reason of first dental visit were not statistically significant. Together, there was no statistically significant difference between rural and urban area, private and public kindergarten, and boy and girl($x^2-test$, p>.05 or Fisher's exact test, p>.05).

• Journal of The Korean Association For Science Education
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• v.36 no.4
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• pp.705-715
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• 2016

The purpose of this research is to analyze elementary students' attention characteristics through attention test and eye tracking on real science classes. The SMI's ETG(eye tracker glasses) mobile eye tracker was used to analyze the attention process of elementary students'. The sampling rate of the ETG is 30Hz. The participants of attention test were elementary 155 6th-grade elementary students and the participants for the eye-tracker were six 6th-grade male students. The eye movements were analyzed using the 'BeGaze Mobile Video Analysis Package' program. The results of this research are as follows. First, the attention test results of elementary students showed high correlation between selective attention and sustained attention (.85) and low correlation between selective attention and self-regulation (.32). Second, the attention types of elementary students were divided into four; attention, inattention, easygoing and hasty. Third, elementary students' attention were divided into top-down, bottom-up, default mode network through analysis of elementary students′ eye-movements during real science classes. Also their attention shift occurred frequently due to various reasons in real class situation. There were three reasons that made elementary students fail to handle knowledge-dependent top-down attention; 1) the cognitive failure of target caused by failing to focus attention, 2) the absence of prior knowledge on target object, 3) the analogical failure of prior knowledge. Finally, elementary students' attention process were schematized based on the analysis of students' eye movements and attention test. This research is expected to be utilized as basic data for developing effective teaching strategies, teaching-learning models and instructional materials.

• The Korean Journal of Pesticide Science
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• v.15 no.4
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• pp.463-470
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• 2011

This study was carried out to survey the residual characteristic of chlorpyrifos and estimate their residues in squash before harvest. The pesticide was sprayed onto the crop at the recommended and its double rates 10 days before the prearranged harvest and sampling was done at 0, 2, 3, 5, 6, 7 and 10 days after spraying. The amounts of the chlorpyrifos residue in the crop was analyzed by chromatographic method. Limit of detection (LOD) of chlorpyrifos was 0.005 mg/kg and its recovery ranged from 95.21 to 102.69%. The initial concentration of chlorpyrifos sprayed with recommended dose exceeded its MRL of 0.1 mg/kg but its concentration was less than its MRL 10 days after application. However its concentration in case of the double dose was over its MRL both immediately and 10 days after application. Biological half-lives of chlorpyrifos sprayed onto squash was 2.5 and 2.9 days at the recommended and double doses, respectively. Ten days later, the residual concentration of chlorpyrifos in squash was decreased substantially. The concentration of chlorpyrifos was estimated in squash at the given day using its regression equations. The estimated concentration of chlorpyrifos in case of application with recommended dose was below its MRL at 10 days after application but its concentration in case of application with double dose was over its MRL at 10 days of the prearranged harvest. The rate of the estimated daily intake (EDI) of chlorpyrifos to its acceptable daily intake (ADI) was 282% right after application but it decreased to less than 18% at 10 days of the prearranged harvest.

• Korean Journal of Health Education and Promotion
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• v.21 no.2
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• pp.17-32
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• 2004

The purpose of this study was to evaluate the patterns of stresses arising from various life styles and their related sociodemographic factors in urban residents. The subjects were recruited from the population of two ‘Dong’s (administrative blocks) representative of Daejeon city through stratified cluster random sampling during the period ranging from June I st to Aug. 31 st, 2003. Self-administered questionnaires, including items asking about subjects' sociodemographic characteristics, daily life styles, measurement of stresses by General Health Questionnaire (Goldberg, 1978), were delivered to 396 residents and their responses were analyzed with the following results. 1. Based on the discriminant scores of HPI, 46.7％ of the subjects were found to have less than 4 points (poor life style), whereas 53.3％ had points higher than 5 (good life style). Higher than 5 points were scored more frequently in females than in the male, in the age group of 40's - 60's than the 30's, in the group with spouse than without, in the group with both spouse and offsprings than without, and in the group owning a house than not. 2. Based on the degree of stress, 17.7％ of the subjects were determined to be healthy, 74.5％ were potentially under stress, and 7.8％ were at higher risk of stress. The proportion of healthy individuals were significantly higher in the male, advanced aged group(40's and 60's), the group with higher education years( over highschool), with higher monthly income over two million Won, and with spouse, than their respective counterparts. On the other hand the proportion of the individuals potentially under stress and at higher risk of stress was significantly higher in the female, in the age group of 30's and over 60's, in the group with academic career lower than middle school, with monthly income lower than two million Won, and without spouse. 3. Based on the relation of HPI with degree of stresses, subjects with HPI scores lower than 4 had increased rate of falling into the groups under potential stress and at higher risk of stress, while on the other hand those with over 5 points were found to be healthy in light of stress. 4. Based on the specific relation of each item of HPI with degree of stress, the proportion of healthy individuals was higher in the groups who take appropriate hours of sleep(7-8hours), who take breakfasts everyday, who take physical exercises everyday, who don't smoke, who don't drink alcohol, who take snacks everyday, who are overweight and obese, whereas the proportion of the group under potential stress and at higher risk of stress was higher in their comparable counterparts. 5. The relation of mean scores of HPI with stress scores in both male and female subjects showed negative correlation that the higher HPI scores, the lower stress scores. 6. Multivariate regression analysis to reveal the factors influencing the stress of the subjects showed that for men the significant factors were age, education, presence of job or not, exercise, subjective health status, with the explanatory power of 26.3％. For women, they included educational years, presence of spouse or not, job, owning a house or not, sleeping hours, drinking habit, taking snacks, subjective health status, with the explanatory power of 31.8％. The above study results suggests that stresses of urban residents have significant correlation with daily life styles and this correlation is also remarkably distinguished by different age and sex.

• Journal of Korean Academy of Fundamentals of Nursing
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• v.5 no.1
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• pp.125-141
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• 1998

The purpose of this research is to analyze the effects of aerobic exercise on body composition, cardiopulmonary function, serum lipid level and antioxidants of obese and normal college female students. The subject group was made up of 13 normal students (below 30% body fat ratio) and 12 obese students (above 30% body fat ratio). After a pretest, the subjects were given an 8-week aerobic program. Then the subjects were given a posttest and analyzed of body composition, serum lipid level, antioxidants and cardiopulmonary function after the 6th and the 8th week of the program. The program schedule was made up of 4 days per week, 60 minutes per day. Test includes B.W., subscapular and triceps subcutaneous fat thickness, change of respiratory gas, and two blood sampling before treadmill exercise and post all out state, which analyzed serum lipid and antioxidants. The subjects performed treadmill exercise starting with 4km/hr of walking and then gradually increase the speed of 1km/hr per minute until all out state. The obtained data were analyzed using SAS program. The statistical methods employed here were one-way ANOVA with repeated measure, Duncan Multiple range test, paired-t test and t-test. The test results and conclusion of this research were as follows. 1. The effects of aerobic exercise on body composition were as follows ; Percent body fat was significantly reduced 6 weeks after the program and lean body mass was significantly increased 8 weeks after the program in both groups(obese group: F=3.44 P=.044, normal group: F=3.30 P=.048). subscapular skinfold of the obese group showed a remarkable decrease after the 6th week(F=4.33 P=.021) triceps skinfold of the normal group showed a remarkable decrease after the 6th and the 8th week(F=4.55 P=.017) compared with readings before the aerobic program, the aerobic program made a bigger difference concerning body fat, lean body mass, subscapular skinfold in the obese group than in the normal group(t=2.41 P=.024, t=2.40 p=.025, t=2.43 p=.028). 2. The effects of aerobic exercise on cardiopulmonary function were as follows ; Maximal $O_2$ uptake/kg was significantly increased 6 weeks after the program in the obese group(F=3.20 P=.054), but not much difference was observed in the normal group. Maximal pulse rate was significantly reduced in both groups after 6 weeks of the program(obese group: F=2.77 P=.087, normal group: F=7.17 P=.001). 3. The effects of aerobic exercise on serum lipid level were as follows ; In a resting period, total cholesterol, Triglyceride, and LDL-cholesterol were slightly higher in the obese group than in the normal group, but HDL-cholesterol was higher in the normal group. But, with the aerobic program, total-cholesterol, Triglyceride, LDL-cholesterol were reduced gradually and HDL-choleterol got increased in both groups, but not much change was noticed in the normal group. However, in the obese group, serum HDL-cholesterol level got increased significantly(F=5.12 P=.012). 4. The effects of aerobic exercise in serum antioxidants were as follows ; In a resting period, the obese group's serum Free Radical and GSSG content were higher than the normal group's and the normal group's serum GSH content was higher than the obese group's. After 6 weeks of the aerobic program, Free Radical was reduced significantly in both groups(obese group: F=13.87 P=.000, normal group: F=18.60 P=.000) In the obese group, 8 weeks after the program, GSH was increased significantly(F=13.78, P=.000). In the normal group, 6 weeks after the program, GSH was reduced but increased again after 8 weeks(F=6.07 P=.005). Plasma GSSG was significantly increased after 8 weeks of exercise in both groups(obese group: F=19.75 P=.000, normal group: F=22.42 P=.000,) Compared with readings before the aerobic program, the aerobic program made a bigger difference serum GSH in the normal group than in the obese group(t=3.37 p=.003). As this result shows, it is known that the regular aerobic exercise improves cardiopulmonary function, body composition, serum lipid effectively and through the serum Free Radical reduction and antioxidant system activation, oxidant stress was suppressed. This effect was higher in the obese group than in the normal one. At least 6weeks exercise period need for improvement of body composition, cardiopulmonary function and activation of antioxidant system. This result suggest that improvement of serum lipid profile was needed longer than 8weeks exercise period.

• Journal of Environmental Science International
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• v.8 no.1
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• pp.7-18
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• 1999

Fauna and biological water quality using benthic macroinvertebrates were analysed and estimated macroinvertebrates. Samples were collected 5 times from the 7 sites in the river between April and December 1997, and the results are summarized as follows. The taxa of benthic macroinvertebrates was totally composed 81 species, 45 genus, 37 families, 15 orders, 8 classes in 3 phyla. Among them, aquatic insects were mostly abundant as 65 species, and also, there were a species of oligochaetes, 2 species of hirundinida, 6 species of gastropods, 5 species of polecypoda, and 2 species of crustaceans. Average individual numbers in the whole sampling sites was 815 per square meter, and insects were abundant (Approx. 80%). Among the insects, the major taxa were respectively ephemeroptera (Approx. 70%) and trichoptera (Approx. 18%). According to the average individual numbers in each site, Chung-do stream (site 1) showed the highest appearance rate as 262 individual/ $m^3$ (32.2%), and the lowest value was at the end of Miryang River (site 7) as 38 individual / $m^3$(4.7%). The dominant species among the whole samples was Ecdyomurus levis Navas, and dominance indices was 0.3. In each site, Ecdyomurus levis Navas was dominant species from site 1 to site 5, and dominant species at site 6 and 7 was respectively Hirudinidae sp. 1. Species diversity index in total average of samples was 2.66. Average of species diversity index according to each study site was the highest value at site 4 (H'=3.47), and site 2, 1, 3, 5, 6, and 7 in that order. According to the water quality as biotic indices, GPI value was 1.49 in total average of Miryang river, and the pollution indices evaluated secondary water quality criteria as $\beta$-mesosaprobics. In each site, the best water quality was at site 3, and it revealed the first water quality criteria as Oligosaprobic. It was then site 1, 2, 4 and 5 in the order of water quality, and was evaluated secondary water quality criteria as $\beta$-mesosaprobics, respectively. Site 6 was also revealed the third water quality criteria as $\beta$-mesosaprobics. The worst water quality was at site 7, which revealed the third water quality criteria as a-mesosaprobics.

• Journal of Ecology and Environment
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• v.29 no.6
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• pp.585-591
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• 2006

We measured the litterfall quantity and investigated the nutrient dynamics in decomposing litter for three years at the LTER sites installed in a deciduous broadleaf natural forest in Mt. Gyebangsan, South Korea. Litterfall production was significantly different among the sampling dates, whereas it was not significantly different among the years. The total annual mean litterfall production for three years was 6,593 kg $ha^{-1}$ $yr^{-1}$ and leaf litter accounted for 82.6% of the litterfall. The leaf litter quantity was highest in Quercus mongolia, followed by leaf of other species, Betula schmidtii, Kaplopanax pictus, Acer pseudo-sieboldianum, etc., which are dominant tree species in the site. The mass loss from the decomposition of leaf litter was fastest in Cortinus controversa (100%), followed by A. preudo-sieboldianum, K. pictus, and B. schmidtii. 100% of litter for C. controversa, 96.1% for A. pseudo-sieboldianum, 92.8% for K. pictus decomposed, while 66.2% of litter for Q. mongolia decayed for 1,003 days. The lower rate of the mass loss in the litter of Q. mongolia may be attributed to the difference in substrate quality, such as lower nutrient concentrations compared with those of other tree species. The concentrations of N, P, and Ca for five litter types increased over time, while the concentrations of K and Mg decreased over time. Compared with the nutrients in the litter of Q. mongolia, the nutrients (N, P, K, Ca, Mg) in the litter of other species, C. controversa, A. pseudo-sieboldianum, and K. pictus, were released more rapidly. The results showed that the mass loss and the nutrient dynamics in the litter are variable depending on the tree species even in the same site conditions.