• Korean Journal of Applied Biomechanics
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• v.23 no.1
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• pp.25-35
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• 2013

This study examined 24 right-handed amateur baseball players. Twelve who had played baseball for more than 6 years were grouped as skilled players, while 12 who had played for 1-3 years were the unskilled player group. The swing motion was divided into four event phases: stance, backswing, impact, and follow-through. The mean and maximum plantar pressure, center of pressure, and ground reaction force were measured during each event phase. The mean and standard deviations for each variables were calculated and differences were validated with the independent sample t-test. A p-value <0.05 was considered statistically significant. The results were as follows. 1)The ideal stance is a stable, balanced position with more than 65% of weight on the right foot. There was significant difference in mean left plantar pressure, while the maximal plantar pressure and mean right plantar pressure did not differ significant. 2)The effective backswing of a skilled player is comprised a rightward shift in weight to build maximum energy. More than 90% of the weight was on the right foot. There was a significant difference in the mean left plantar pressure, while the maximal plantar pressure and mean right plantar pressure did not differ significantly. 3) For an effective impact, a rapid shift in weight to the left foot is essential, so that a power hit is obtained. Significant difference in the mean and maximum plantar pressures of both feet were observed. 4)Follow-through requires wight balance, more on the right than the left, without leaning leftward. There was no significant difference in the mean or maximum plantar pressure. 5)The center of plantar pressure should move from the center of the foot to the toe. 6)The analyses of the ground reaction force suggest that a good swing involves a gradual shift in weight to the right side and a rapid leftward shift at impact. Good balance, with the center of gravity on the right side at follow-through, is also required.

• Journal of Korea Water Resources Association
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• v.48 no.10
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• pp.793-806
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• 2015

The simulation of natural streamflow at ungauged basins is one of the fundamental challenges in hydrology community. The key to runoff simulation in ungauged basins is generally involved with a reliable parameter estimation in a rainfall-runoff model. However, the parameter estimation of the rainfall-runoff model is a complex issue due to an insufficient hydrologic data. This study aims to regionalize the parameters of a continuous rainfall-runoff model in conjunction with a Bayesian statistical technique to consider uncertainty more precisely associated with the parameters. First, this study employed Bayesian Markov Chain Monte Carlo scheme for the estimation of the Sacramento rainfall-runoff model. The Sacramento model is calibrated against observed daily runoff data, and finally, the posterior density function of the parameters is derived. Second, we applied a multiple linear regression model to the set of the parameters with watershed characteristics, to obtain a functional relationship between pairs of variables. The proposed model was also validated with gauged watersheds in accordance with the efficiency criteria such as the Nash-Sutcliffe efficiency, index of agreement and the coefficient of correlation.

• Journal of the Korea institute for structural maintenance and inspection
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• v.11 no.3
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• pp.95-104
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• 2007

This study was focused on the effect of concrete strength and lateral ties of concrete columns subjected to eccentric compressive loads. The twenty-four concrete columns with $200mm{\times}200mm$ square cross-section were tested. The main variables were concrete strength, spacing and configuration of lateral ties, and eccentricity ratios. From the experiment, the followings were investigated ; 1) In all cases, it was observed that the increase of concrete compressive strength led to the decrease of ductility. Also, as the eccentricity ratios increased, the effect of ductility enhancement by lateral ties decreased. 2) As the ties spacing decreased from 100mm to 30mm, the magnitude of axial load acting on the concrete column showed an enhancement of 1.1~1.2 times and the descending curve after a peak moment presented a smooth decline. 3) The high-strength concrete columns required a design of lateral ties to increase the volumetric ratios and density of tie spacing to sustain a proper strength and ductility. Accordingly, regardless of concrete strength, the current AIK design code to specify the maximum tie spacing of concrete columns was proven to lead to the poor strength and ductility for seismic design. Therefore, it is necessary to develop a new seismic design code that connects volumetric ratios and tie spacing of concrete columns with concrete strength.

• Korean Journal of Childcare and Education
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• v.1 no.1
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• pp.103-124
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• 2005

This study aims to investigate and analyze how toddlers' characteristics and child care center's environments including facilities and care-givers' characteristics affect toddlers' behavior in child care center using observational methods. Total 40 toddlers in same numbers of boys and girls participated in this study. Average age of tollers were the 31.7 months ranging from 27 months to 35 months. The toddlers were observed with the observation schedule modified from observation categories of Holloway and Reichhart-Erickson(1988). Data were analysed by Pearson's correlation, t-test, one away ANOVA, Duncan Test and stepwise regression using the SPSSWIN Version. The results of the study were as follow: First, the toddlers' behaviors were related to all the toddlers' characteristics. Second, the toddlers' behaviors were related to all the characteristics of the child care facilities such as the types of facilities, the class size and the caregiver-toddler ratio. Third, the toddler' behaviors were related to caregivers' variables such as the total care experience in centers, the experience with toddler care, the martial status, the certificate types except the child rearing experience and the educational level. Fourth, the toddlers' characteristics were more significantly related to the behavior of them than those of child care centers' environment.

• Korean Business Review
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• v.11
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• pp.277-293
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• 1998

The purpose of this study is to analyse the overall relationship between the advertisement expenses and the two major indicies of business performance, that is, the total amount of sales and the discipline have contrasted the expenses for commercial advertisement with the total amount of sales or with the business performance, respectively, utilizing data on a specific product observed through 3 to 5 years. This study attempts to enlarge the scope of observation and the content of analysis. In order to attain the purpose of this study, the rate of increase in the advertisement expenses is taken as the independent variable and the two major indicies of business performance, the total amount of sales and the resultant interest, as the dependent variables. Business companies or firms which have continually been listed on the board of Korea Stock Exchange for 14 years, from 1982 to 1995, were grouped into four major business categories; 1)Food and beverage industries, 2)Fiber, clothings, and leather industries, 3) Medicine, chemistry, oil, coal, and rubber industries, and 4) Assembled mechanics and metallurgy, machinery, and maintenance industries. Utilizing the KIS-DATA, compiled by Korea Credit Evaluation, Ltd., 30 to 40 samples of business companies or firms were randomly selected from each category. Finally 125 samples were selected and put into regression analyses and follow-up tests by appropriate statistical models, in order to verify if there were any noticeable correlations. The final result obtained through the afore-mentioned research method shows that the amount of advertisement expenses has strong correlations with the amount of sales and the resultant interest. Viewed by business category, in the case of fiber, clothings, and leather industries, the relationship turned out to be significant only with the rate of increase in the total amount of sales, while, in the case of food and beverage industries, the rate of increase in the total amount of sales showed a negatively significant correlations.

• Journal of Korea Water Resources Association
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• v.46 no.4
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• pp.425-437
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• 2013

This study performed the bivariate drought frequency analysis for duration and severity of drought, using copula functions which allow considering the correlation structure of joint features of drought. We suggested the confidence intervals of duration-severity-frequency (DSF) curves for the given drought duration using stochastic scheme of monthly rainfall generation for 57 sites in Korea. This study also investigated drought risk via illustrating the largest drought events on record over 50 and 100 consecutive years. It appears that drought risks are much higher in some parts of the Nakdong River basin, southern and east coastal areas. However, such analyses are not always reliable, especially when the frequency analysis is performed based on the data observed over relatively short period of time. To quantify the uncertainty of drought frequency curves, the droughts were filtered by different durations. The 5%, 25%, 50%, 75%, and 95% confidence intervals of the drought severity for a given duration were estimated based on the simulated rainfall time series. Finally, it is shown that the growing uncertainties is revealed in the estimation of the joint probability using the two marginal distributions since the correlation coefficient of two variables is relatively low.

• Journal of the Korean BIBLIA Society for library and Information Science
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• v.29 no.1
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• pp.277-298
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• 2018

This study aims to demonstrate the importance of information literacy instructions by showing effects of information literacy skills on critical thinking dispositions among high school students. We collected 761 survey responses from high school students and conducted multiple regression analysis to examine the relationships between the two variables. The findings show that (1) students' information search skills affect their pursuit of truth, openness, inquiring mind, and objectivity, (2) the information analytic skills influence the levels of pursuit of truth, openness, and objectivity, (3) the information presentation and delivery skills affect the levels of inquiring mind, organization, and self-trust, and, (4) the information evaluation skills influence the levels of pursuit of truth, openness, inquiring mind, organization, objectivity, and self-trust. However, students' synthesis and application skills of students did not affect their critical thinking dispositions. To sum up, we observed the influence of information literacy skills on critical thinking dispositions. The results of this study provide foundations for maintaining and developing information literacy instructions in school libraries.

• Journal of the Korea Convergence Society
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• v.8 no.7
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• pp.323-330
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• 2017

Emotion in early childhood has been observed to make an important effect on behavioral development. The teacher has coached to develop good behavior based on considering emotional response rather than rational response. This study was to determine significance of emotional coaching for behavior development according emotion recognized by non-verbal measurement system developed specially in this study. The participants were 44 people and were asked to study in four experimental situation. The experiment was designed to four situation such as class without coaching, behavioral coaching, emotion coaching, and emotion coaching based on emotional recognition system. The dependent variables were subjective evaluation, behavioral amplitude, and HRC (Heart Rhythm Coherence) of heart response. The results showed the highest positive evaluation, behavioral amplitude, and HRC at emotion coaching based on emotional recognition system. In post-doc analysis, the subjective evaluation showed no difference between emotion coaching and system based emotion coaching. However, the behavioral amplitude and HRC showed a significant response between two coaching situation. In conclusion, quantitative data such as behavioral amplitude and HRC was expected to solve the ambiguity of subjective evaluation. The emotion coaching of teacher using emotional recognition system was can be to improve positive emotion and psychological stability for children.

• Journal of the Korea Concrete Institute
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• v.22 no.2
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• pp.199-208
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• 2010

In order to substitute FRP bar for steel bar in new structures, it is necessary to establish a reliable design code. But relatively little research has been conducted on the material in Korea. So, a total of 22 beam specimens (18 GFRP reinforced concrete and 4 conventional steel reinforced concrete) were constructed and tested. In the first phase of the experiment, it was carried out to observe flexural behavior, and collect deflection and crack data. In order to eliminate of the uncertainty by the shear reinforcements and induce flexural failure mode, any stirrup were not used and only shear span-depth ratio were adjusted. However, almost beams were broken by shear and the ACI 440.1R, CSA S806, which were used to design test beams, showed considerable deviation between prediction and test results of shear strengths. Therefore in the second phase of the study, shear failure modes and behavior were observed. A standard specimen had dimensions of 3,300 mm long ${\times}$ 800 mm wide ${\times}$ 200 mm effective depth. Clear span and shear span were 2,800 mm, 1,200 mm respectively. Control shear span-depth ratio was 6.0. Four-point bending test over simple support was conducted. Variables of the specimens were concrete compressive strength, type and elastic modulus of reinforcement, shear span-depth ratio, effective reinforcement ratio, the effect of bundle placing method and cover thickness.

• Journal of Environmental Science International
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• v.25 no.10
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• pp.1349-1368
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• 2016

Concentrations of fine particulate matter ($PM_{2.5}$) and several of its particle constituents measured outside homes in Houston, Texas, and Los Angeles, California, were characterized using multiple regression analysis with proximity to point and mobile sources and meteorological factors as the independent variables. $PM_{2.5}$ mass and the concentrations of organic carbon (OC), elemental carbon (EC), benzo-[a]-pyrene (BaP), perylene (Per), benzo-[g,h,i]-perylene (BghiP), and coronene (Cor) were examined. Negative associations of wind speed with concentrations demonstrated the effect of dilution by high wind speed. Atmospheric stability increase was associated with concentration increase. Petrochemical source proximity was included in the EC model in Houston. Area source proximity was not selected for any of the $PM_{2.5}$ constituents' regression models. When the median values of the meteorological factors were used and the proximity to sources varied, the air concentrations calculated using the models for the eleven $PM_{2.5}$ constituents outside the homes closest to influential highways were 1.5-15.8 fold higher than those outside homes furthest from the highway emission sources. When the median distance to the sources was used in the models, the concentrations of the $PM_{2.5}$ constituents varied 2 to 82 fold, as the meteorological conditions varied over the observed range. We found different relationships between the two urban areas, illustrating the unique nature of urban sources and suggesting that localized sources need to be evaluated carefully to understand their potential contributions to $PM_{2.5}$ mass and its particle constituents concentrations near residences, which influence baseline indoor air concentrations and personal exposures. The results of this study could assist in the appropriate design of monitoring networks for community-level sampling and help improve the accuracy of exposure models linking emission sources with estimated pollutant concentrations at the residential level.