• Journal of Korean Society of Water and Wastewater
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• v.19 no.6
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• pp.827-837
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• 2005

In this study, we derived a new non-dimensional variable including bubble size and air diffusing area by Buckingham's theorem for making a practical correlation with experimental results. Firstly, we drew a relationship between a non-dimensional variable, $NH/u_s$, which has a form of Froude number and destratification efficiency with a simple theoretical consideration. Then we derived two non-dimensional variables by Buckingham's ${\pi}$-theorem and equating them with a form of $Fr_N$ for making single parameter to correlate overall destratification efficiency. As the result, the single parameter Be number shows a correlations with destratification efficiencies obtained from laboratory and pilot experiments. Also, for the practical applications, we conducted multiple regression analysis using Be and tank area to make predictive equations about destratification efficiency. The result also shows a successful correlations with destratification efficiency ($R^2$>0.9, p<0.001). Using this equation, we proposed a new design methodology with respect to bubble diffusing area.

• Journal of computational fluids engineering
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• v.17 no.3
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• pp.39-44
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• 2012

In this study, a longitudinal pitch effect on in-line tube bank heat transfer has been analyzed numerically. To verify the accuracy of the solver model and boundary conditions, global Nusselt number(Nu) and pressure drop across the 2 row tube bank are compared with the existing experimental correlations under 500 ~ 2,000 Reynolds number(Re) range. By changing transverse pitch($S_T$) or longitudinal pitch($S_L$) separately in tube bank, we're trying to identify the each effect on heat transfer. We found that the effect of transverse pitch can be accounted for Reynolds number evaluated with maximum velocity($V_{max}$) at the smallest flow area similar to most existing correlations. Variation of the longitudinal pitch($S_L$) has a greater impact on the heat transfer compared to the transverse pitch($S_T$). Overall Nusselt number increases with larger longitudinal pitch($S_L$), however individual Nusselt number of the tube row has significant difference after the first row.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2003.04a
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• pp.225-228
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• 2003

For the purpose of finding out the distributions of groundwater uses, the effect of facilities on the parameter and the correlations among measurements, various statistical analysis were carried out with the data of groundwater quality measurements from January to December in 2002. 1. The rates of groundwater for drinking water were 10.5% in Yangcheon-Gu, 10.2% in Kangdong-Gu, and 9.9% in Eunpyung-Gu. The rates of other uses of groundwater were shown to be 58.1%(786 wells) for civil defense emergency, 22.1%(299 wells) for contamination-concerning, 9.8%(133 wells) for water quality monitoring, consisting of 90% of all groundwater. 2. The 52.6% of groundwater for drinking were demonstrated to be appropriate while 91.9% for tither uses-domestic, industrial, agricultural uses- were shown to be proper. 3. For drinking water, the average values of colar, turbidity, NH3-N, F, and Fe were 11.216 degree, 2.138 NTU, 2.458mg/l, 0.212mg/1 and 0.507mg/1 respectively. 4. In cases of drinking water wells for emergency, the results of statistical analysis showed that building year of the wells, depth and pumping rate didn't affect on whether it was proper for that use or not. It were shown that there were linear correlations between depth and NO$_3$-N(-0.171) and F￣(0.332) while the correlation coefficients were 0.381 and -0.169 between the building year of well and depth and pumping rate respectively.

• The Korean Journal of Health Service Management
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• v.10 no.4
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• pp.97-107
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• 2016

Objectives : This study aims to : (i) characterize and differentiate between two different periods of baby boomers, (ii) study the utilization of their health care services, and (iii) establish effective ways of providing better health service utilization and preventive policy strategies for upcoming and older generations. Methods : A multiple regression analysis using descriptive statistics, frequency analysis, and dummy variables was utilized to access the presence of correlations between socio-demographic factors and health care service utilization. Results : Medical insurance type, marital status, and chronic disease were factors that influenced health care service utilization. Furthermore, the factors that influenced individual medical expenses were cohabitation, inpatient days, and chronic disease. Conclusions : Primary findings and exploratory statistics revealed that there were strong correlations and interaction among some of the predictor variables. Because of the chronologically limited nature of the sample data set gathered in 2012, it would be helpful to continue to develop or research related constructs that may capture relationships more effectively among extended populations.

• Journal of Korea Game Society
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• v.17 no.6
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• pp.199-208
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• 2017

Since the study by Turkle(1995), the concept of identity play in MMORPGs has been employed primarily to explain the reflection of users' identity in the avatar creation process in online games. This study attempts to conceptualize the identity play of the design process in which the user uses the avatar customizing system to create an avatar in the virtual world. This research verified the model of identity play through players' avatars, a model of the components of identity play constructed. The aims of this study pursued through an analysis of correlations of users' attitudes toward avatars. This study performed structural equation modeling to verify hypotheses about the variables that affect online identity play.

• The Korean Journal of Rehabilitation Nursing
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• v.9 no.2
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• pp.145-152
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• 2006

Purpose: The purpose of this study was to investigate the depression, anxiety, stress response and self-care, to analyze the correlation among depression, anxiety, stress response and self-care by gender, and to determine factors associated with self-care in diabetic patients. Method: The subjects of this study were 103 participants with diabetes mellitus. Data were analyzed by chi-square test, t-test, Pearson correlation coefficient and multiple regression analysis by using SAS program. Result: Items for self-care evaluation by gender were significant differences in hospital visit, hypoglycemia preparation, proper hygiene, taking a rest, foot injury check, drinking, and smoking. The female patients are more likely to have higher self-care score than the male patients. However, there were no differences in depression, anxiety and stress response by gender. In male patients, there were positive correlations between the degree of depression and stress response, the degree of anxiety and stress response. In female patients, there were positive correlations between the degree of depression and stress response, the degree of anxiety and stress response. In multiple regression analysis, gender and experienced admission is associated with self-care. Conclusion: We should consider integrated approaches for psychological problems in the management of diabetic patients.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.8 no.3
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• pp.338-350
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• 1996

A numerical analysis is carried out to study the two-dimensional steady state natural convection from vertical wires immersed in cold pure water. The surface of the wire is $0^{\circ}C$ unifrom temperature. Results of the analysis are presented for free stream temperature from $0^{\circ}C$ to $25^{\circ}C$ and the aspect ratio N from $5.26{\times}10^{-3}$ to $1.0{\times}10^{-3}$. The effects of the density extremum and aspect ratio on the flow pattern and the heat transfer characteristics are discussed As the aspect ratio N becomes larger, in the range of $1.0^{\circ}C{\leq}T_{\infty}{\leq}4.4^{\circ}C$ and $6{^{\circ}C}{\leq}T_{\infty}{\leq}17^{\circ}C$, the effect of Pr number on the heat transfer is shown to be more significant than the aspect ratio. Investigating into the effect of the density extremum on the heat transfer from wires, the new heat transfer correlations are suggested with the relation of average Nu mumber vs. modified Ra number. Here, the coefficient values C of correlations are presented as the function of density extremum parameter $R^*$. The effects of the density extremum parameter are also discussed.

• Journal of Periodontal and Implant Science
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• v.38 no.2
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• pp.199-206
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• 2008

Purpose: Variation in the morphology of gingival papilla may be determined by the shape and position of anatomic crown as well as contact area and embrasure form of individual teeth. However, periodontal biotype classification is regarded to be subjective because of the lack of definite criteria. In this study, we defined the objective parameters which constitute the periodontal biotype and measured their relationship. Materials and Methods: 109 of dental casts were prepared using three dimensional scanner and specialized reconstruction software, then acquiredvirtual models were sent to the 20 professional dentists to define the specific periodontal biotypes. Several parameters around periodontal structures were measured from the virtual models; facial surface area of the anterior tooth (AT), anterior papillary area (AP), proportion of the dento-papillary complex, clinical papillary length (PL), and clinical papillary angle (PA). Statistical analysis was performed to confirm the relationship among parameters. Results: Coincidence rate of periodontal biotype within observers was $63.77{\pm}16.05%$. Coincidence rate between observers was $76.15{\pm}16.43%$. Among the parameters measured, PL showed the most positive correlations and PA presented the most negative correlations. The parameter of the AP and PL of six maxillary anterior teeth showed significant correlation coefficient. Conclusion: Anterior papillary area and clinical papillary length would be objective parameters for determining the consistent periodontal biotypes.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.31 no.12
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• pp.994-1001
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• 2007

Numerical analysis has been carried out to investigate air-side convective heat transfer characteristics in a compact heat exchanger with circular tubes and continuous plate fins. Simulation results such as air velocity and temperature distributions are presented, and heat transfer coefficients are compared with previous experimental correlations. Three models of standard and RNG $k-{\varepsilon}$, and Reynolds stress are applied for turbulence model applicability. Predicted heat transfer coefficient from the models of standard and RNG $k-{\varepsilon}$ are very close to those of the heat transfer correlations while there are relatively large difference, more than 17 percentage in the result from the Reynolds stress model. From the calculated results a correlation for Colburn j factor in the compact heat exchanger system is suggested.

• Korean Journal of Community Nutrition
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• v.14 no.1
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• pp.114-122
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• 2009

The purpose of this study was to identify the factors of university residence hall foodservice quality which has correlations with subjective QOL (quality of life) of target customers. A total of 176 questionnaires from students of 4 universities in Daegu, Gyeongbuk area were used for the analysis. The male students using residence hall foodservices were highly satisfied with 'clean appearances of employees' ($4.86{\pm}1.25$) and 'clean facilities' ($4.79{\pm}1.26$), while the degree of satisfaction with 'convenient facilities' ($4.50{\pm}1.20$) showed the highest score with female students. Ranking analysis using Spearman's ${\rho}$ revealed that there were significant correlations between students' satisfactions with the dimensions of 'foods and kindness of employees', 'hygiene', 'nutrition', and 'convenience' and their QOL, even though physical QOL of female students showed no significant correlation with satisfaction towards residence hall foodservices. As a conclusion, there should be efforts to improve the QOL of target customers through foodservice quality management.