• International Journal of Highway Engineering
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• v.18 no.6
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• pp.153-160
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• 2016

OBJECTIVES : The objective of this study is to develop a traffic accident model of a roundabout based on the type of land use. METHODS : The traffic accident data from 2010 to 2014 were collected from the "traffic accident analysis system (TAAS)" data set of the Road Traffic Authority. A multiple linear regression model was utilized in this study to analyze the accidents based on the type of land use. Variables such as geometry and traffic volume were used to develop the accident models based on the type of land use. RESULTS : The main results are as follows. First, the null hypothesis that the type of land use does not affect the number of accidents is rejected. Second, four accident models based on the type of land use have been developed, which are statistically significant (high $R^2$ values). Finally, the total entering and circulating volumes, area of the central island, number of speed breakers, mean number of entry lanes, diameter of the inscribed circle, mean width of the entry lane, area of the roundabout, bus stops, and number of circulatory roadways are analyzed to see how they affect the accident for each type of land use. CONCLUSIONS : The development of the accident models based on the type of land use has revealed that the accident factors at a roundabout are different for each case. Thus, more speed breakers in commercial areas and an inscribed circle of proper diameter in commercial and residential areas are determined to be important for reducing the number of accidents. Additionally, expanding the width of the entry lanes, decreasing the area of the roundabouts in residential areas, and reducing the conflict factors such as bus stops in green spaces are determined to be important.

• The Journal of the Korea Contents Association
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• v.20 no.4
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• pp.686-701
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• 2020

The purpose of this study is to find out how employee's gratitude disposition affects Organizational Citizenship Behavior(OCB) and empirically validating multiple mediation effect of perceived organizational support(POS) and job satisfaction. For this study, an online survey has been conducted on office workers to analyze 380 sets of answers, reviewed reliability and validity through CFA and used SPSS 25.0, AMOS 25.0, Macro Process 3.0, a bootstrap method to test hypothesis. As a result, it is verified that an employee's gratitude disposition positively affects OCB, POS and job satisfaction and that there exists a multiple mediation effect of POS and job satisfaction. In this study, it is validated that an employee's gratitude disposition has a positive influence on OCB and an employee's gratitude disposition, an individual trait, is a related antecedent variable of POS. The result of this study is meaningful that it suggests boosting gratitude disposition, a positive psychological factor, in an organization can positively affect employees' job attitude and organization effectiveness.

• Journal of Korean Library and Information Science Society
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• v.47 no.3
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• pp.365-382
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• 2016

In this paper, impact of science and technology information service quality satisfaction and perceived importance on the user loyalty was studied to find the way of improvement of information service quality. To analyze the impact among service quality variables, the research questions and hypothesis are set and statistical analysis on 641 survey answers was conducted. The correlation between satisfaction and perceived importance regarding each service quality item was high. Relationship between satisfaction of every item of the service quality and overall satisfaction was verified by multiple regression analysis. As a result, the five out of seven independent variables are statistically significant influence to the dependent variable. Relationship between the perceived importance and loyalty for each item was verified by multiple regression analysis was confirmed that the four out of seven independent variables are statistically significant influence to the dependent variable. The overall satisfaction is having an effect on loyalty verified through simple regression analysis.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.42 no.4
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• pp.194-202
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• 2019

Reliability analysis of the components frequently starts with the data that manufacturer provides. If enough failure data are collected from the field operations, the reliability should be recomputed and updated on the basis of the field failure data. However, when the failure time record for a component contains only a few observations, all statistical methodologies are limited. In this case, where the failure records for multiple number of identical components are available, a valid alternative is combining all the data from each component into one data set with enough sample size and utilizing the useful information in the censored data. The ROK Navy has been operating multiple Patrol Killer Guided missiles (PKGs) for several years. The Korea Multi-Function Control Console (KMFCC) is one of key components in PKG combat system. The maintenance record for the KMFCC contains less than ten failure observations and a censored datum. This paper proposes a Bayesian approach with a Dirichlet mixture model to estimate failure time density for KMFCC. Trends test for each component record indicated that null hypothesis, that failure occurrence is renewal process, is not rejected. Since the KMFCCs have been functioning under different operating environment, the failure time distribution may be a composition of a number of unknown distributions, i.e. a mixture distribution, rather than a single distribution. The Dirichlet mixture model was coded as probabilistic programming in Python using PyMC3. Then Markov Chain Monte Carlo (MCMC) sampling technique employed in PyMC3 probabilistically estimated the parameters' posterior distribution through the Dirichlet mixture model. The simulation results revealed that the mixture models provide superior fits to the combined data set over single models.

• Journal of the Korean Institute of Landscape Architecture
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• v.30 no.3
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• pp.64-72
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• 2002

The purpose of this paper is to examine the effects of interior landscape that influence preference at a department store in order to answer the research question; What are the effective factors of interior landscape that affect preference at a department store. After review of the effect of interior landscape, and the interior landscape at a department store, we constructed a literature framework and have formulated the hypothesis of this research. We have analyzed the data which surveyed 108 visitors about the interior landscape in a department store, using factor analysis, Pearson's correlation analysis, and the multiple linear regression method. We found that; 1) eleven variables can be selected for the effects of interior landscape at department store: accessibility, image, stay, distinction, comfort, complexity, cleanness, mystery, purification of atmosphere, noise and harmony. Among the 11 independent variables used to study the effect of interior landscape at a department store, the image and purification of atmosphere highly affect preference. 2) These 11 variables are grouped by factor analysis as effects of amenity, attractiveness and identity. 3) As a result of multiple regression analysis, independent variables influencing preference were proved statistically significant at one percent level. 4) Regarding their relative contribution of interior landscape effect at a department store, the effects of amenity was the most important and it showed a level of importance 1.4 times higher than the effect of identity, and 1.25 times higher than the effect of attractiveness. The research results suggest the need for guidelines for the creation of interior landscape at department stores. The approach and analysis method adopted by this research is highly useful for the evaluation of interior landscape criteria at a department store. It is recommended that more practical study on factors affecting user's preference be performed in the future.

• Journal of Preventive Medicine and Public Health
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• v.34 no.4
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• pp.437-443
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• 2001

Objectives : This study was peformed to assess the association between the social support and blood pressure(BP) in a rural community. Methods : A cross-sectional survey, comprising a health examination including BP, height and weight and a questionnaire-based interview which investigated social support, demographic factors, smoking, drinking, and etc. was peformed between February 10th and March 5th, 1998. The survey included 318 persons who were over than 30-year-old in the rural community of Kwangju, Republic of Korea. We excluded persons who taking antihypertensive medications or who provided incomplete information; we subsequently analyzed the data from 284 persons. In order to test the hypothesis of an association between BP and social support controlling confounders such as age, educational level, working time, body mass index, smoking and drinking, the data was analyzed using multiple linear regression analysis. Results : The subjects were composed of 109(38.4%) males and 175(61.6%) females with mean ages of 62.0 years and 61.1 years, respectively. The hypertension prevalence was 41.3% among males and 45.1% among females. In the correlation analysis, higher total social support scores correlated significantly with lower systolic BP in both males and females. The hypertension prevalence increased significantly with the decreasing of the social support in males. In multiple regression analysis, systolic and diastolic blood pressure showed a negative association with social support in both males and females, although this was not statistically significant. Conclusions : Larger and broader studies are required in the future in order to identify the association between the social support and BP.

• Biomolecules & Therapeutics
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• v.29 no.1
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• pp.83-89
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• 2021

Multiple system atrophy (MSA) is a neurodegenerative disease characterized by presence of α-synuclein-positive inclusions in the cytoplasm of oligodendrocytes. These glial cytoplasmic inclusions (GCIs) are considered an integral part of the pathogenesis of MSA, leading to demyelination and neuronal demise. What is most puzzling in the research fields of GCIs is the origin of α-synuclein aggregates in GCIs, since adult oligodendrocytes do not express high levels of α-synuclein. The most recent leading hypothesis is that GCIs form via transfer and accumulation of α-synuclein from neurons to oligodendrocytes. However, studies regarding this subject are limited due to the absence of proper human cell models, to demonstrate the entry and accumulation of neuronal α-synuclein in human oligodendrocytes. Here, we generated mature human oligodendrocytes that can take up neuronderived α-synuclein and form GCI-like inclusions. Mature human oligodendrocytes are derived from neural stem cells via "oligosphere" formation and then into oligodendrocytes, treating the cells with the proper differentiation factors at each step. In the final cell preparations, oligodendrocytes consist of the majority population, while some astrocytes and unidentified stem cell-like cells were present as well. When these cells were exposed to α-synuclein proteins secreted from neuron-like human neuroblastoma cells, oligodendrocytes developed perinuclear inclusion bodies with α-synuclein immunoreactivity, resembling GCIs, while the stem cell-like cells showed α-synuclein-positive, scattered puncta in the cytoplasm. In conclusion, we have established a human oligodendrocyte model for the study of GCI formation, and the characterization and use of this model might pave the way for understanding the pathogenesis of MSA.

• The Journal of the Korea Contents Association
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• v.22 no.10
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• pp.309-319
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• 2022

As a study on the mechanisms by which creativity is improved in an organization, this study tried to verify the serial multiple mediating effects of relational energy and creative process engagement in the effect of leader-member exchange(LMX) on creativity. To test the hypothesis, a survey was conducted on 200 workers in China, and 154 of them were analyzed. The analysis used model 6 of the PROCESS macro. As a result, first, LMX has positive effects on creativity. Second, relational energy mediated the relationship between LMX and creativity. Third, creative process engagement mediated the relationship between LMX and creativity. Forth, relational energy and creative process engagement continuously mediated the relationship between LMX and creativity. Based on these research results, the implications and limitations of this study were presented, and methods to improve creativity in the organization were discussed.

• Journal of Engineering Education Research
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• v.27 no.1
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• pp.3-12
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• 2024

The degree-linked programs for employees, operated by joint training centers in specialized universities that have implemented work-study integrated programs, are educational programs that require an annual government budget of around 80 billion KRW. However, the 70+ universities running these programs face issues such as a decline in academic achievement and an increase in dropout rates among students. In this paper, I conducted multiple regression analysis based on observed and measured information to examine whether the participating students in these programs are achieving an appropriate level of academic performance and to identify the factors that universities need to invest in to achieve that level. To do this, I hypothesized a causal relationship between the university's input factors and students' academic achievement, and used the SPSS program to analyze the statistical data, confirming the validity of the hypothesis. The collected data for the study were obtained through a survey developed using a Likert 4-point scale, which quantified the distribution of grades among students enrolled in IT-related departments offering the degree-linked programs for employees and the emotional contact efforts made by the universities to motivate them for academic success. Particularly, through the results of multiple regression analysis, it was confirmed that these input factors, unlike those for students in general education programs, require more personalized and frequent interactions.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.6
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• pp.2635-2640
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• 2014

Sera of cancer patients may contain antibodies that react with a unique group of autologous cellular antigens called tumor-associated antigens (TAAs). The present study aimed to determine whether a mini-array of multiple TAAs would enhance antibody detection and be a useful approach in esophageal cancer detection and diagnosis. Our mini-array of multiple TAAs consisted of eleven antigens, p53, pl6, Impl, CyclinB1, C-myc, RalA, p62, Survivin, Koc, CyclinD1 and CyclinE full-length recombinant proteins. Enzyme-linked immunosorbent assays (ELISA) were used to detect autoantibodies against eleven selected TAAs in 174 sera from patients with esophageal cancer, as well as 242 sera from normal individuals. In addition, positive results of ELISA were confirmed by Western blotting. In a parallel screening trial, with the successive addition of antigen to a final total of eleven TAAs, there was a stepwise increase in positive antibody reactions. The eleven TAAs were the best parallel combination, and the sensitivity and specificity in diagnosing esophageal cancer was 75.3% and 81.0%, respectively. The positive and negative predictive values were 74.0% and 82.0%, respectively, indicating that the parallel assay of eleven TAAs raised the diagnostic precision significantly. In addition, the levels of antibodies to seven antigens, comprising p53, Impl, C-myc, RalA, p62, Survivin, and CyclinD1, were significantly different in various stages of esophageal cancer, which showed that autoantibodies may be involved in the pathogenesis and progression of esophageal cancer. All in all, this study further supports our previous hypothesis that a combination of antibodies might acquire higher sensitivity for the diagnosis of certain types of cancer. A customized mini-array of multiple carefully-selected TAAs is able to enhance autoantibody detection in the immunodiagnosis of esophageal cancer and autoantibodies to TAAs might be reference indicators of clinical stage.