• The Journal of Korean Academy of Prosthodontics
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• v.42 no.2
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• pp.175-191
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• 2004

Statement of problem: Platelet-rich plasma(PRP) is well known to be very effective method to stimulate and accelerate the healing of bone and soft tissue. However, there are few reports which deal with the mechanisms of the PRP on the activation of the osteoblasts. Purpose: This study was aimed to investigate the effect of growth factors in PRP on the activity of osteoblasts. Material and method: To evaluate the effect on human, human osteoblast cell line was cultured. PRP was extracted from the blood of a healthy volunteer. Using the recombinant growth factors of PDGF, $TGFT-\beta$, IGF-1, bFGF which are mainly found at bone matrix and their neutralizing antibody, the effect of PRP on the attachment and proliferation of osteoblasts was evaluated. To evaluate the autocrine and paracrine effects, conditioned media(CM) of PRP was made and compared with PRP. By the western blot analysis, the expression of growth factors in PRP, CM was examined. Cell morphology was compared by the light microscope. Results : 1) The effects of CM on osteoblast were similar to the effects of PRP. 2) PRP, CM, recombinant $TGF-\beta$, bFGF, IGF-1 showed significantly higher cellular attachment than control(p<0.05) in the cell attachment assay. In the cell proliferation assay, PRP, CM, recombinant $TGF-\beta$, IGF-1, bFGF, PDGF increased significantly cell proliferation(p<0.01). Among the recombinant growth factors, IGF-1 showed the highest cellular attachment and proliferation. 3) In the western blot assay, bFGF, IGF-1, PDGF weve equally expressed in PRP and CM. 4) The attachment of osteoblast cell decreased significantly after the addition of neutralizing antibody against $TGF-\beta$, IGF-1(p<0.05). In the cell proliferation assay, the addition of neutralizing antibody against $TGF-\beta$, bFGF, PDGF, IGF-1 decreased significantly the cellular proliferation(p<0.05). The amount of decreasing in the cell attachment and proliferation is the highest in at-lGF-1. 5) The cells in control group were flattened and elongated with a few cellular processes in the a light microscope. But, the cells appeared as spherical, plump cells with well developed cellular processes in experimental groups. The cells in PRP and CM had more prominent developed features than recombinant growth factor groups. Conclusions : These findings imply that PRP maximize the cellular activity in early healing period using the synergistic effect, autocrine, paracrine effects of growth factors and increase the rate and degree of bone formation.

• Journal of the Korean Operations Research and Management Science Society
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• v.39 no.2
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• pp.111-130
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• 2014

For the key factors determining victory of combat, many works have been focusing on qualitative analyses in the past. As military training paradigm changes along with technology developments, demands for scientific analysis to prepare future military strength increase regarding military training results, and big data analysis has opened such possibility. We analyze the data from KCTC (Korea Combat Training Center) training to investigate the factors affected victory in offensive operations. In this context, we develop a way to measure the victory and the factors related to it from existing studies and military doctrines. We first identify Independent variables that affect offensive operations through variable selection and propose a mathematical model to explain combat victory by performing multiple regression analysis. We also verify our results with battalion-level live training data as well as previous studies on victory factors in the military doctrines.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.17 no.6
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• pp.141-158
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• 2022

This study identifies related factors by analyzing the effects of the psychological characteristics and competency factors of traditional market merchants on business performance, and at the same time verifies the moderating effect of government support policies. The research focus was on verifying the causal relationship. This study was conducted targeting the representative traditional market merchants in the metropolitan area who have experience in traditional market specialization projects or are currently in the process of specialization projects. An empirical study was performed based on the collected data. The analysis results are as follows. First, it was found that self-esteem as a psychological characteristic factor of merchants, customer management competency as merchant competency, and informatization capability had a significant positive (+) effect on financial performance among business performance. Second, as a result of examining the moderating effect of government support policies, it was found that product capability had a significant positive (+) effect on financial performance among business performance. It was found that self-esteem and product competency had a significant positive (+) effect on the will to continue business among business performance. The practical results of this study are the research papers to measure the business performance of traditional market merchants using the government support policy as a moderating variable, using the psychological characteristics and competency factors of traditional market merchants as independent variables. For this purpose, it will be positively evaluated that the psychological characteristics of merchants and merchant competency factors affect business performance, and that meaningful research results are derived by analyzing the moderating effect of government support.

• Journal of Korea Society of Digital Industry and Information Management
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• v.7 no.1
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• pp.111-125
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• 2011

Smartphone is becoming as a core device of mobile environment. The purpose of this study is to investigate the factors affecting customer's buying decision on smartphone. Based on prior studies and cases, this study identifies network effect, switching cost, function, design, brand, after service, price as affecting factors of customer's buying decision on smartphone. It also aims to investigate the relationship between network effect/switching cost and re-purchasing. Result shows that network effect brand, after service are significantly related to customer's buying decision on smartphone by device types, but switching cost, function, design, price are not. Network effect also was found to be significantly related to the re-purchasing. The result of this study may provide a guideline of supply strategy with smartphone suppliers.

• International journal of advanced smart convergence
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• v.10 no.2
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• pp.31-36
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• 2021

This study aims to provide basic data on establishing online learning by identifying the effects of self-efficacy as a medium on factors affecting self-control according to self-determination motivation through contactless online learning due to Covid-19. The research method used SPSS 25 and Sobel test to examine the causal relationship between the spokesmen and 196 middle and high school students in W-city, Gangwon-do. Self-determination motivation has had a significant effect on self-efficacy and self-control, and self-efficacy has been shown to have a significant effect on self-control. Also, Self-efficacy had a partial mediating effect on self-determination motivation affecting self-control. Based on this, fundamental and continuous development of online education programs to promote self-control of online learners is required, and efforts should be made to support learners' capabilities through psychological counseling.

• Magazine of the Korean Society of Agricultural Engineers
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• v.15 no.2
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• pp.2980-3001
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• 1973

Nozzle is a part of sprayer and is consists of several elements; swirl plate, vortexchamber, cap and body. The travelling distance of sprayed particles is important in the wide reach nozzle. The factors to influence the travelling distance of the sprayed particles may be the helical angle of swirl plate, the distance of vortex hamber, the slope and the size of cap hole. The study was conducted to examine the effects of these factors on the travelling distance. The results of this study are summarized as follows; 1) There was higher positive correlation(+0.96) between the maximum travelling distance for which amount of sprayed particles was 5cc/cm min. and centro-position of the travelling distance. 2) There was a higher positive correlation(+0.85) between total discharge of sprayed particles and the centro-position of the travelling distance. 3) Main effects and interaction effects of helical angle, pressure, vortex chamber distance and cap slope were significantly affected the travelling distance of sprayed particles. 4) Main effects of helical angle, pressure and cap slope were especially highly significant to influence the travelling disance. 5) Helical angle, pressure, vortex chamber distance and cap slope influenced spraying forward velocity of dise hole, among which cap slope and pressure of nozzle was the most important factors. 6) Effect of change of helical angle on the travelling distance of sprayed particles, was generally a quadratic, the least value of the distance being showed about $45^{\circ}$ and the largest at about $15^{\circ}\;and\;55^{\circ}$, the decreasing rate of the change between $15^{\circ};and\;25^{\circ}$ was very small. 7) Effect of change of pressure on the travelling distance sprayed particles was generally a linear, the increasing rate of the charge was about 1.68, which was the most effective compared to the change of the other factors. 8) Effect of change of vortex chamber distance on the spraying distance was also generally a linear, the increasing rate being about 0.16, which was the least effective. 9) Effect of change of cap slope on the travelling distance was also generally a linear, the increasing rate was about 0.61 and its effect was about medium.

• Journal of the Korea Society of Computer and Information
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• v.24 no.7
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• pp.161-168
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• 2019

The purpose of this study is to analyze the mediating effects of anger level on the effects of middle school students' school adjustment on smartphone addiction. In order to accomplish the purpose of this study, the following research problems were set up. First, what is the relationship between Chinese smartphone addiction, anger level, and school adjustment of Chinese middle school students? Second, what is the effect of smartphone addiction on middle school students' anger level and school adjustment? Third, what is the mediating effect of the level of anger in the process of affecting the school adjustment to smartphone addiction by Chinese middle school students? The subjects of this study were five city schools and seven municipal schools in J-do, among which 450 students were enrolled from April 23 to May 18, 2018. A total of 439 copies were used for the analysis, except for 11 unexplained questionnaires or unfairly responded to the collected questionnaires. The conclusions based on the results of this study are as follows. First, there are negative correlations between the sub-factors of smartphone addiction and the sub-factors of school adjustment. Among them, tolerance is only positively correlated with the peer relationship. The sub-factors of smartphone addiction have negatively correlated with anger expression, anger control, and anger suppression. Second, the effect of sub-factors of smartphone addiction on the level of anger was 3.6%, and the effect on school adjustment was 4.2%. Third, The anger level of the middle school students affected the school adjustment by the smartphone addiction has a partial mediating effect of 0.8%.

• Journal of the Korea Safety Management & Science
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• v.13 no.4
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• pp.81-89
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• 2011

The purpose of this study is to understand the safety factors of the public transportation and recommend the experimental factors of customer satisfaction. The survey consist of 28 questions of 5 factors about users characteristics on roads, railways, ships, and flights. As a result of multiple regression analysis, we knew that there are three potential factors affecting customer satisfaction. The Factors are named 'expected', 'attitude', 'management', and the variable of factors affect customer satisfaction significantly. Therefore, it is good strategy for effective working to improve customer satisfaction that maintain attitude with safety minds, try to specialized management, and creating expectation for safety considering the difference by the type of public transportation. After considering the meaningful result, for the development of policies for customer satisfaction for safety, we have to consider expected, attitude, and management factors of workers and officials that influence customer safety and try to improve the managerial factors considering the characteristics of their own.

• Journal of Industrial Convergence
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• v.20 no.11
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• pp.75-83
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• 2022

This study analyzes whether investor sentiment and liquidity explain the momentum phenomenon in the Korean stock market and whether it is a risk factor for the asset pricing model. The empirical analysis used the monthly returns of non-financial companies listed on the stock market during the period 2000-2021. As a result of the analysis, first, it was found that there is a momentum effect in Korea. This is the same result as the previous study, and since 2000, the momentum effect has been accepted as a general phenomenon in the Korean stock market. Second, if we look at the portfolio based on investor sentiment, investor sentiment is influencing momentum. In particular, when investor sentiment is negative, the return on the winner portfolio is high. Third, as a result of the analysis based on liquidity, the momentum effect disappears and a reversal effect appears. Fourth, it was found that investor sentiment and liquidity influence the momentum effect. This is a result of the strong momentum effect in the illiquid stock group with negative investor sentiment. Fifth, as a result of analyzing the effect of each factor on stock returns, it was found that both investor psychology and liquidity factors have a significant impact on returns. The estimated results provide evidence that the inclusion of these two factors in the Carhart four-factor model significantly increases the predictive power of the model. Therefore, it can be said that investor sentiment factors and liquidity factors are important factors in determining stock returns.

• Journal of Korea Society of Industrial Information Systems
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• v.23 no.5
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• pp.43-59
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• 2018

The first purpose of this study is to find out whether internal support factors such as evaluation system, education support program, and human resources of universities are factors that influencing the motivation of technology transfer and commercialization among those engaged in technology transfer and commercialization activities. Second, verified the regulation effect of social support from the cause-and-effect relationship between motivation of technology transfer commercialization and the said internal factors. In order to analyze the above research, a questionnaire survey was conducted for the professors and employees engaged in the technology transfer and commercialization organization of 40 universities in Korea. A total of 160 surveys were distributed, of which 145 were collected. The results of analysis using SPSS Statistics 22.0 are as follows. First, all internal factors of university such as evaluation system, education support program, and human resources have significant influence on the motivation for technology transfer and commercialization. Second, as a result of analyzing the regulation effect of the social support in relation to the internal factor of the university and the motivation of technology transfer and commercialization, the quasi regulation effect can be founded in between evaluation system and motivation of technology transfer and commercialization. However, there is no regulation effect of social support between the education support program, human resources and motivation for technology transfer and commercialization. Based on the results of this study, suggestions can be founded for establishing a support policy for those who are engaged in technology transfer and commercialization in universities.