• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.7
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• pp.192-202
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• 2019

This study was a descriptive study to investigate the factors influencing on self-esteem, ego resilience, impulsivity and life stress on smartphone addiction among college students. The subjects include college students in some areas. Data was collected in November and December, 2018. Total 231 college students were analyzed in the study. Collected data was analyzed in frequency, percentage, and t-test to examine differences in smartphone addiction according to general characteristics. Pearson's correlation was performed to examine correlations between smartphone addiction and main variables, and the factors influencing smartphone addiction were analyzed in multiple regression. The findings show that genera, satisfaction with college life, hours of using a smartphone, hours of using SNS, ego resilience, impulsivity, and life stress had significant effects on smartphone addiction. The study examined relations between general characters and smartphone addiction and found that the level of smartphone addiction was high in female college students, those who were not satisfied with college life, and used a smartphone and SNS for many hours. Ego resilience had negative correlations with smartphone addiction, and impulsivity and life stress had positive correlations with it. Multi-variate regression analysis results show that gender, ego resilience, and life stress were factors that had important influences on the smartphone addiction of college students, having explanatory power of 35.6%. In short, colleges and universities need to develop a school-level program to improve the college life of students and reduce their stress to the minimum and create an environment of encouraging them to grow power of controlling their lives so that they can prevent smartphone addiction.

• The Journal of the Korea institute of electronic communication sciences
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• v.8 no.5
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• pp.779-784
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• 2013

This study aims to look into the relationship between the parents's family history of diabetes and factors of metabolic syndrome focusing on Korean adult males with a family history of diabetes. The data used for the study was collected from the 2010 Korea National Health and Nutrition Examination Survey. The subjects of the study totaled 2,045. For statistical analysis, double sampling general linear regression was used and the statistical significance was p<0.05. As a result of a multi-variate analysis with general characteristics corrected, the following was discovered: when fathers had a family history of diabetes, girth increased by 2.5cm, fasting blood sugar(glu) increased by 9.6mg/dL and neutral fat increased by 41.6mg/dL When the mothers had a family history of diabetes, girth increased by 2.4cm, fasting blood sugar(glu) increased by 15.4mg/dL, and the neutral fat increased by 27.2mg/dL. In conclusion, when the fathers had a family history of diabetes, their children's girth, fasting blood sugar and neutral fat were significantly higher, and when the mothers had a family history of diabetes, their children's girth and fasting blood sugar were significantly higher.

• Journal of Korean society of Dental Hygiene
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• v.12 no.4
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• pp.695-705
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• 2012

Objectives : The purpose of this study is to evaluate the appearance of having relationship between the exposure to lead and cadmium and the dental caries targeting adults in the Republic of Korea. Methods : The study was designed as a cross-sectional study, using the data of the Fourth Korea National Health and Nutrition Examination Survey. The subjects as 1,966 people, who were confirmed the appearance of dental caries among 1,991 people of having been offered the heavy-metal concentration in blood. Statistical analysis was conducted using SPSS 19.0, according to complex sampling design. Results : As a result of multi-variate analysis on factors of dental caries, in Model I without correction, the gender, age, educational level, appearance of lifelong smoking, daily toothbrushing frequency, appearance of using dental floss, and subjective oral health status were recognized as important factors. In Model II with correction of gender and age, the educational level, daily toothbrushing frequency, and subjective oral health status were recognized as statistically significant factors. In Model III with correction of all factors, the gender, age, educational level, appearance of using dental floss, and subjective oral health status were functioning as statistically significant factors. As a result of statistically analyzing relationship between the exposure to lead and cadmium and the dental caries targeting adults, it was analyzed that there is no significant correlation. However, in case of lead, the tendency of being grown the cross ratio of dental caries could be examined in model I, which didn't correct disturbance factor, model II, which corrected gender and age, and model III, which corrected all variables of disturbance factor. Conclusions : The exposure to lead and cadmium was indicated to have no relationship with adults' dental caries. However, a continuous research of relationship was considered to be necessary by using Korea National Health and Nutrition Examination Survey, which is surveyed in the future.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.7
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• pp.244-254
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• 2020

The purpose of this study was to analyze the differences in dating violence perception of dating violence perception of university students. As a research tool, CTS2 was used as a measure of dating violence, a measure developed by Kim(1999) was used, and a measure of dating violence by Jeong(2013) was used. Data analysis was performed using independent sample t-test and multi-variate analyses. The results are summarized as follows. First, female students showed higher differences in total violence against violence and psychological violence than boys, while boys showed higher physical violence than girls. Health majors were significantly higher in total dating violence and psychological violence than students in humanities and social sciences. There was no significant difference in dating violence offenses with or without sexual experience. Only psychological violence showed an interaction effect between gender and sex experience. Second, female students were significantly higher than male students with significant differences in recognition and sub-factors. Health majors were significantly higher in both date violence perception and lower factors than humanities and social sciences. Students without sexual experience perceived overall dating violence more than students with sexual, physical and cyber violence being significantly higher.

• Journal of Korean Ophthalmic Optics Society
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• v.15 no.3
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• pp.293-297
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• 2010

Purpose: The aim of the current study was to compare body mass index (BMI) with waist circumference (WC) as a predictor of elevated intraocular pressure (IOP). Methods: The subjects were consisted of 458 adults, aged 20 year or above, of one community in Kyunggi-do. Mean IOPs were stratified jointly for BMI and WC tertiles. Multi-variate linear regression analysis was also used to compare between BMI and WC. Results: Although any BMI tertiles were not associated with IOP within each tertile of WC, WC tertiles was significantly related to elevation of IOP within the third BMI tertile (${\geq}24.9kg/m^2$). After adjusting for age and sex, only WC showed significant association with IOP. In additional adjustment for lifestyle variables, both BMI and WC were significantly associated with elevation of IOP. However, the results showed the stronger association of IOP with WC than BMI, whether they were adjusted by age and sex or additionally lifestyle variables. Conclusions: These data showed that BMI and WC were positively associated with IOP. However, WC appeared to be a better indicator for higher IOP than BMI.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.16 no.2
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• pp.73-82
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• 2017

In this research, we tried to check the applicability of a Chow test to the linear models which are generated in the process of transportation planning or traffic flow analyses. The Chow test is a very popular statistical method which is being used to see if the coefficients from two separate linear regression models are equal or not. In order to prove the effectiveness of the Chow test, we found the linear relationships between speed and density under the situations such as driving in daytime and in nighttime on a rainy day. Based on the two months of Joong-Bu Expressway traffic data, we proved that the Chow test is useful to testify the similarity between two linear regression models. And this statistical tool seems to be able to have a very important role in traffic flow analysis or in transportation planning process. Finally, we expect the Chow test be implemented even to the non-linear regression models or to the multi-variate models.

• Journal of Korean Society of Forest Science
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• v.86 no.2
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• pp.241-250
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• 1997

The study was conducted to make a map for selecting righteous tree species for each site by digital terrain analysis. We set an algorithmic value for each tree species' characteristics with distribution pattern analysis, and the soil types were digitized from data indicated on soil map. Mean altitude, slope, aspect and micro-topography were estimated from the digital map for each block which had been calculated by regression equations with altitude. The results obtained from the study could be summarized as follows 1. We could develope a method to select righteous tree species for a given site with concern of soil, forest condition and topographic factors on Muju-Gun in Chonbuk province(2,500ha) by the terrain analysis and multi-variate digital map with a personal computer. 2. The brown forest soils were major soil types for the study area, and 29 tree species were occurred with Pinus densiflora as a dominant species. The differences in site condition and soil properties resulted in site quality differences for each tree species. 3. We tried to figure out the accuracy of a basic program(DTM.BAS) enterprised for this study with comparing the mean altitude and aspect calculated from the topographic terrain analysis map and those from surveyed data. The differences between the values were less than 5% which could be accepted as a statistically allowable value for altitude, as well as the values for aspect showed no differences between both the mean altitude and aspect. The result may indicate that the program can be used further in efficiency. 4. From the righteous-site selection map, the 2nd group(R, $B_1$) took the largest area with 46% followed by non-forest area (L) with 23%, the 5th group with 7% and the 4th group with 5%, respectively. The other groups occupied less than 6%. 5. We suggested four types of management tools by silvicultural tree species with considering soil type and topographic conditions.

• Korean Journal of Environmental Biology
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• v.28 no.4
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• pp.179-187
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• 2010

The Theory of Island Biogeography describes that the number of species on an island affected by island area and distance from the mainland. This study was performed to compare and analyze the community structure of the macro-invertebrates in three isolated islands, around Korean waters in terms of the Theory of Island Biogeography. Macrobenthic animals were collected using a modified underwater quadrat in August 2009. A total of 104 macrobenthic species were sampled with a mean density of 399 individuals $m^{-2}$ and biomass of 1,506.70 g $m^{-2}$. Based on the abundance and biomass data, there were 10 dominant species accounting for approximately 67.17% of total individuals. The highest densities were found in the amphipoda Amphipoda spp., the bivalvia Modiolus agripetus and Mytilus coruscus, the Sipunculida Phascolosoma scolops and the polychaeta Syllidae unid.. On the contrary, the top ten species made up 95.66% of the total biomass while the three most abundant, the bivalves M. coruscus, Streostria circumpicta and M. agripetus. The conventional multi-variate statistics (cluster analysis and non-metric multi-dimensional scaling) applied to assess spatial variation in macrobenthic assemblages. Cluster analysis and nMDS ordination analysis based on the Bray-Curtis similarity identified 2 station groups. The group 1 was consisted with Gageodo (except for lower station at Transect 2) and Dokdo station and was numerically dominated by the polychaetes Eunice antennata and Syllidae unid., the cirripedia Megabalanus rosa and the bivalvia M. coruscus. However, group 2 was associated with Sohwado station and was characterized by high abundance of the anomura Petrolisthes japonicus, the gastropoda Lirularia pygmaea and the brachiopoda Coptothyris grayi. In conclusion, these results suggested that the species diversity and community structure of macrobenthos in three isolated island seemed slightly related to island area and distance from the mainland.

• Korean Journal of Environmental Agriculture
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• v.26 no.1
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• pp.17-24
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• 2007

This study was carried out to classify the streams at rural watersheds by characteristics of water quality. The water quality data of 319 steams at rural watersheds in Korea were selected. Multivariate analysis was used for this purpose. The cases were divided into 5 types, and then factor analysis and cluster analysis were done. The characteristics of water quality of rural watersheds can be showed more than 40% of total water quality by first factor(organic matters and nutrients). The cluster analysis of extracted factors using factor analysis was carried out. The results showed that the Case 1 and Case 2 were classified 4 communities, Case 3 was classified 5 communities and Case 4 and 5 were classified 3 communities. Among 5 types cases, to classified the steams of rural watersheds, Case 4 - 7 water quality items - was selected as a desirable case. Many kinds of statistical analysis can be used to classify the streams of rural watersheds. Our results showed a good example to evaluate the water quality properties in Korean rural watershed.

• Journal of the Korean Association of Geographic Information Studies
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• v.25 no.1
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• pp.133-149
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• 2022

Existing domestic studies on estimating rice yield were mainly implemented at the level of cities and counties in the entire nation using MODIS satellite images with low spatial resolution. Unlike previous studies, this study tried to estimate rice yield at the level of eup-myon-dong in Gimje-si, Jeollabuk-do using Sentinel-2 satellite images with medium spatial resolution, rainfall and soil data, and then to evaluate its accuracy. Five vegetation indices such as NDVI, LAI, EVI2, MCARI1 and MCARI2 derived from Sentinel-2 images of August 1, 2018 for Gimje-si, Jeollabuk-do, rainfall and paddy soil-type data were aggregated by the level of eup-myon-dong and then rice yield was estimated with gamma generalized linear model, an expanded variant of multi-variate regression analysis to solve the non-normality problem of dependent variable. In the rice yield model finally developed, EVI2, rainfall days in September, and saline soils ratio were used as significant independent variables. The coefficient of determination representing the model fit was 0.68 and the RMSE for showing the model accuracy was 62.29kg/10a. This model estimated the total rice production in Gimje-si in 2018 to be 96,914.6M/T, which was very close to 94,470.3M/T the actual amount specified in the Statistical Yearbook with an error of 0.46%. Also, the rice production per unit area of Gimje-si was amounted to 552kg/10a, which was almost consistent with 550kg/10a of the statistical data. This result is similar to that of the previous studies and it demonstrated that the rice yield can be estimated using Sentinel-2 satellite images at the level of cities and counties or smaller districts in Korea.