• Maxillofacial Plastic and Reconstructive Surgery
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• v.32 no.3
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• pp.218-228
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• 2010

Components of dental resin-based restorative materials are reported to leach from the filling materials even after polymerization. Hydroquinone (HQ) is one of the major monomers used in the dental resin and is known as a carcinogen. Thus, carcinogenic risk of HQ leaching from the dental resin becomes a public health concern. The present study attempted to examine the carcinogenic potentials of HQ on the human epithelial cell, which is the target cell origin of the most of oral cancers. Cytotoxicity of HQ was observed above 50${\mu}M$ as measured by LDH assay, indicating a relatively low toxicity of this substance in human epithelial cells. The parameters of neoplastic cellular transformation such as cell saturation density, soft agar colony formation and cell aggregation were analyzed to examine the carcinogenic potential of HQ. The study showed that 2-week exposure of HQ showed the tendency of increase in the saturation density and the significant enhancement of soft agar colony formation at the highest dose, 50 ${\mu}M$ only. It is suggested that HQ has a weak potential of carcinogenicity. When cells were treated with HQ and TPA, a well-known tumor promoter, the parameters of neoplastic cellular transformation was significantly increased. This result indicates that the potential risk of carcinogenicity from HQ is largely dependent upon the presence of promoter. Exposure of 50 ${\mu}M$ HQ increased the time-dependent apoptosis as measured by the ELISA kit. This concentration coincides with a dose of neoplastic transformation, indicating a possible link between apoptosis and HQ-induced cellular transformation. Hydroquinone generated Reactive Oxygen Species (ROS) which was evidenced by the treatment of antioxidants such as trolox and N-acetyl cysteine and the GSH depleting agent, BSO. Antioxidants blocked the generation of ROS and the GSH depleting agent, BSO dramatically increased the ROS production. Since HQ is known to increase ROS production thru activation of transcriptional factor such as c-Myb and Pim-1, it is speculated that ROS generation by HQ plays a role in the activation of oncogene, which may lead to neoplastic transformation. In addition, ROS is involved in the alteration of signal transduction, which regulates the apoptosis in many cellular systems. Thus, ROS-mediated apoptosis may be involved in the HQ-induced carcinogenic processes. Protein kinase C (PKC) is known to play pivotal roles in neoplastic transformation of cells and its high expression is often found in a variety of types of tumors including oral cancer. PKC translocation of PKC-${\alpha}$ was observed following HQ exposure. Altered signaling system may also play a role in the transformation process. Taken together, HQ leached from the dental resin does not pose a significant threat as a cancer causing agent, but its carcinogenic potential can be significantly elevated in the presence of promoter. The mechanism of HQ-induced carcinogenesis involved ROS generation, apoptosis and altered signaling pathway. The present study will provide a valuable data to estimate the potential risk of HQ as a carcinogen and understand mechanism of HQ-induced carcinogenesis in human epithelial cells.

• Journal of The Korean Association For Science Education
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• v.22 no.4
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• pp.872-881
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• 2002

Student questioning is included in the priority of science literacy, to enable students to solve problems by exploring questions, communicating and constructing knowledge(AAAS, 1989). Also, the essence of student questioning in science lies in its function as a link between thinking and learning. But educators did not pay much attention to students' questioning in Korea. The purpose of this study was to investigate the effects of science question enhancement instruction on students' science questioning level and achievement. Also, this study showed the effects of other variables(logical thinking, science achievement, interest, and gender) on students' science questioning level. The pretest-posttest control group design group design was used. The sample was consisted of 80 second grade middle school students in experimental group(Science question enhancement instruction) and 74 students in control group(Traditional learning). Students in both groups were received identical content instruction on the unit 'Structures and functions of plant'. These groups were treated for 15 hours during 6 weeks. Students' questions were rated using the four levels described by the Middle School Students' Science Question Rating Scale(r= .96,)(Cuccio-Schirripa & Steinner, 2000). Science achievement data were collected using a 17 item multiple choice test(Cronbach ${\alpha}$= .84). To investigate students' logical thinking ability, a abridged GALT(Cronbach ${\alpha}$= .69) was used. Five-way ANOVA, ANCOVA, and multiple regression analysis were used to analyze the results. The results indicated that students who received instruction on researchable questioning outperformed those students who were not instructed on high-order questioning(p< .01). Results of correlations indicated that instruction(r= .640), science achievement(r= .311) and logical thinking ability(r= .212) was significantly and positively related with students' questioning level. But, interest and gender did not show any significant correlation with students' questioning level. Science question enhancement instruction was more effective on science achievement than the traditional instruction(p< .01).

• Information Systems Review
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• v.18 no.2
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• pp.79-106
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• 2016

Service innovation is one means of gaining an advantage in a highly competitive environment. Although numerous studies have stressed the importance of service innovation, traditional good-dominant logic is still used in service innovation literature. Furthermore, few studies have been conducted on the link between service innovation and its antecedents in terms of service-oriented approach. To fill the gap, this article theoretically and empirically examines service innovation and its antecedents and consequences. Based on service-dominant logic and resource advantage theory, the current study aims to understand the effect of antecedents on service innovation as well as to identify the effect of service innovation on firm performance (i.e., non-financial and financial performance). Three service innovation activities, namely service creation-focused innovation, service delivery-focused innovation, and customer interaction-focused innovation, and four antecedents of service innovation, including human resource management capability, collaboration capability, marketing capability, and information technology capability, are identified based on Den Hertog (2000)'s service innovation framework. By using the empirical data collected from 189 service firms in Korea, this study explores the causal relationship among antecedents, service innovation and firm performance. Findings indicate that human resource management and marketing capabilities influence the three types of service innovation, whereas collaboration and information technology capabilities have a significant effect on both service creation-focused innovation and service delivery-focused innovation. In particular, human resource management capability is strongly related to customer interaction-focused innovation. The three types of service innovation have a positive influence on non-financial performance, whereas service delivery-focused innovation and customer interaction-focused innovation positively influence financial performance. These results support the crucial effects of antecedents, such as human resource management, collaboration, marketing and information technology capabilities, on service innovation.

• KDI Journal of Economic Policy
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• v.31 no.1
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• pp.239-276
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• 2009

The paper investigates the possible relationship between earnings prediction by security analysts and special ownership ties that link security companies those analysts belong to and firms under analysis. "Security analysts" are known best for their role as information producers in stock markets where imperfect information is prevalent and transaction costs are high. In such a market, changes in the fundamental value of a company are not spontaneously reflected in the stock price, and the security analysts actively produce and distribute the relevant information crucial for the price mechanism to operate efficiently. Therefore, securing the fairness and accuracy of information they provide is very important for efficiencyof resource allocation as well as protection of investors who are excluded from the special relationship. Evidence of systematic distortion of information by the special tie naturally calls for regulatory intervention, if found. However, one cannot presuppose the existence of distorted information based on the common ownership between the appraiser and the appraisee. Reputation effect is especially cherished by security firms and among analysts as indispensable intangible asset in the industry, and the incentive to maintain good reputation by providing accurate earnings prediction may overweigh the incentive to offer favorable rating or stock recommendation for the firms that are affiliated by common ownership. This study shares the theme of existing literature concerning the effect of conflict of interests on the accuracy of analyst's predictions. This study, however, focuses on the potential conflict of interest situation that may originate from the Korea-specific ownership structure of large conglomerates. Utilizing an extensive database of analysts' reports provided by WiseFn(R) in Korea, we perform empirical analysis of potential relationship between earnings prediction and common ownership. We first analyzed the prediction bias index which tells how optimistic or friendly the analyst's prediction is compared to the realized earnings. It is shown that there exists no statistically significant relationship between the prediction bias and common ownership. This is a rather surprising result since it is observed that the frequency of positive prediction bias is higher with such ownership tie. Next, we analyzed the prediction accuracy index which shows how accurate the analyst's prediction is compared to the realized earnings regardless of its sign. It is also concluded that there is no significant association between the accuracy ofearnings prediction and special relationship. We interpret the results implying that market discipline based on reputation effect is working in Korean stock market in the sense that security companies do not seem to be influenced by an incentive to offer distorted information on affiliated firms. While many of the existing studies confirm the relationship between the ability of the analystand the accuracy of the analyst's prediction, these factors cannot be controlled in the above analysis due to the lack of relevant data. As an indirect way to examine the possibility that such relationship might have distorted the result, we perform an additional but identical analysis based on a sub-sample consisting only of reports by best analysts. The result also confirms the earlier conclusion that the common ownership structure does not affect the accuracy and bias of earnings prediction by the analyst.

• Journal of Service Research and Studies
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• v.10 no.1
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• pp.33-53
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• 2020

The purpose of this study is to empirically examine the causal relationship of CSR activities, customer trust and CCID, customer behavior intention(B.I) in the relationship between CSR activities and customer behavior intention(B.I) in the insurance industry, thereby enable top management of insurance company to take it in their consideration that CSR activity help link to customer behavioral intention by customer trust in them and CCID. To achieve the purpose of the study, the hypothesis was established based on preceding research and theoretical background regarding CSR, trust, CCID, behavioral intention(B.I). And this study conducted AMOS statistical analysis based on effective 526 survey data collected from insurance customers across country through online research company. The result of this empirical study is as follows. First, insurance company's CSR activity has a positive impact on customer's trust and CCID, but it did not have a direct significant effect on the customer's behavioral intention(B.I). Second, both customer's trust and CCID have a positive and significant effect on customer's behavioral intention. Third, we have also found that both Trust and CCID played a mediating role between CSR activity and B,I. Fourth, it was found that authenticity did not moderate the enfluence relationship between CSR activity and Trust, CCID. The result of this study shows that insurance company's active CSR activity increase customer trust, thereby create a sense of unity between the customer and the company, In addition, it shows that when CSR activities are mediated by customer trust and CCID, it could lead to customer behavioral intention(B.I) such as repurchasing and positive word-of-mouth activities. to others. The result of this study will contribute to the future research on CSR literature and the marketing strategy of insurance companies.

• Korea journal of population studies
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• v.29 no.1
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• pp.185-207
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• 2006

Predominant explanations of the persistence of sex segregation ill occupations link job choices to profoundly gendered responses to childbearing and other family demands, arguing that women are more likely to seek jobs which are in some sense compatible with motherhood, either because they are family friendly (flexible, low intensity work) or because they are easy to exit and re-enter. In this paper, I examine the effect of occupational sex segregation on job exits into the labor market among women, with a special attention to the role of childbearing and child rearing. I use data from detailed employment histories gathered from the National Longitudinal Survey of Youth (NLSY) in continuous time event history models. My results indicate that women in female dominated jobs are less likely to exit their jobs than women in other types of occupations. Further this relationship is not shaped by motherhood. While mothers or pregnant women are more likely to leave work, mothers in female-dominated occupations are slightly less likely to leave employment than mothers in other occupations. These results are not consistent with the ideas that women's choice of female-dominated occupations expresses a gendered identity and women strategically seek jobs which accommodate maternal roles. Taken together, my findings do not provide support to the idea that women choose female-dominated occupations because they are easier to integrate with motherhood (except for the pregnancy period).

• Journal of Intelligence and Information Systems
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• v.20 no.2
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• pp.123-136
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• 2014

Recently, online shopping has further developed as the use of the Internet and a variety of smart mobile devices becomes more prevalent. The increase in the scale of such shopping has led to the creation of many Internet shopping malls. Consequently, there is a tendency for increasingly fierce competition among online retailers, and as a result, many Internet shopping malls are making significant attempts to attract online users to their sites. One such attempt is keyword marketing, whereby a retail site pays a fee to expose its link to potential customers when they insert a specific keyword on an Internet portal site. The price related to each keyword is generally estimated by the keyword's frequency of appearance. However, it is widely accepted that the price of keywords cannot be based solely on their frequency because many keywords may appear frequently but have little relationship to shopping. This implies that it is unreasonable for an online shopping mall to spend a great deal on some keywords simply because people frequently use them. Therefore, from the perspective of shopping malls, a specialized process is required to extract meaningful keywords. Further, the demand for automating this extraction process is increasing because of the drive to improve online sales performance. In this study, we propose a methodology that can automatically extract only shopping-related keywords from the entire set of search keywords used on portal sites. We define a shopping-related keyword as a keyword that is used directly before shopping behaviors. In other words, only search keywords that direct the search results page to shopping-related pages are extracted from among the entire set of search keywords. A comparison is then made between the extracted keywords' rankings and the rankings of the entire set of search keywords. Two types of data are used in our study's experiment: web browsing history from July 1, 2012 to June 30, 2013, and site information. The experimental dataset was from a web site ranking site, and the biggest portal site in Korea. The original sample dataset contains 150 million transaction logs. First, portal sites are selected, and search keywords in those sites are extracted. Search keywords can be easily extracted by simple parsing. The extracted keywords are ranked according to their frequency. The experiment uses approximately 3.9 million search results from Korea's largest search portal site. As a result, a total of 344,822 search keywords were extracted. Next, by using web browsing history and site information, the shopping-related keywords were taken from the entire set of search keywords. As a result, we obtained 4,709 shopping-related keywords. For performance evaluation, we compared the hit ratios of all the search keywords with the shopping-related keywords. To achieve this, we extracted 80,298 search keywords from several Internet shopping malls and then chose the top 1,000 keywords as a set of true shopping keywords. We measured precision, recall, and F-scores of the entire amount of keywords and the shopping-related keywords. The F-Score was formulated by calculating the harmonic mean of precision and recall. The precision, recall, and F-score of shopping-related keywords derived by the proposed methodology were revealed to be higher than those of the entire number of keywords. This study proposes a scheme that is able to obtain shopping-related keywords in a relatively simple manner. We could easily extract shopping-related keywords simply by examining transactions whose next visit is a shopping mall. The resultant shopping-related keyword set is expected to be a useful asset for many shopping malls that participate in keyword marketing. Moreover, the proposed methodology can be easily applied to the construction of special area-related keywords as well as shopping-related ones.

• Journal of Intelligence and Information Systems
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• v.19 no.4
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• pp.97-121
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• 2013

With the growing importance of knowledge for sustainable competitive advantages and innovation in a volatile environment, many researches on knowledge sharing have been conducted. However, previous researches have mostly relied on the questionnaire survey which has inherent perceptive errors of respondents. The current research has drawn the relationship among primary participant behaviors towards the participation level in knowledge sharing, basically from online user behaviors on Wikipedia, a representative community for online knowledge collaboration. Without users' participation in knowledge sharing, knowledge collaboration for creating knowledge cannot be successful. By the way, the editing patterns of Wikipedia users are diverse, resulting in different revisiting periods for the same number of edits, and thus varying results of shared knowledge. Therefore, we illuminated the participation level of knowledge sharing from two different angles of number of edits and revisiting period. The behavioral dimensions affecting the level of participation in knowledge sharing includes the article talk for public discussion and user talk for private messaging, and community registration, which are observable on Wiki platform. Public discussion is being progressed on article talk pages arranged for exchanging ideas about each article topic. An article talk page is often divided into several sections which mainly address specific type of issues raised during the article development procedure. From the diverse opinions about the relatively trivial things such as what text, link, or images should be added or removed and how they should be restructured to the profound professional insights are shared, negotiated, and improved over the course of discussion. Wikipedia also provides personal user talk pages as a private messaging tool. On these pages, diverse personal messages such as casual greetings, stories about activities on Wikipedia, and ordinary affairs of life are exchanged. If anyone wants to communicate with another person, he or she visits the person's user talk page and leaves a message. Wikipedia articles are assessed according to seven quality grades, of which the featured article level is the highest. The dataset includes participants' behavioral data related with 2,978 articles, which have reached the featured article level, with editing histories of articles, their article talk histories, and user talk histories extracted from user talk pages for each article. The time period for analysis is from the initiation of articles until their promotion to the featured article level. The number of edits represents the total number of participation in the editing of an article, and the revisiting period is the time difference between the first and last edits. At first, the participation levels of each user category classified according to behavioral dimensions have been analyzed and compared. And then, robust regressions have been conducted on the relationships among independent variables reflecting the degree of behavioral characteristics and the dependent variable representing the participation level. Especially, through adopting a motivational theory adequate for online environment in setting up research hypotheses, this work suggests a theoretical framework for the participation level of online knowledge sharing. Consequently, this work reached the following practical behavioral results besides some theoretical implications. First, both public discussion and private messaging positively affect the participation level in knowledge sharing. Second, public discussion exerts greater influence than private messaging on the participation level. Third, a synergy effect of public discussion and private messaging on the number of edits was found, whereas a pretty weak negative interaction effect of them on the revisiting period was observed. Fourth, community registration has a significant impact on the revisiting period, whereas being insignificant on the number of edits. Fifth, when it comes to the relation generated from private messaging, the frequency or depth of relation is shown to be more critical than the scope of relation for the participation level.

• Journal of the East Asian Society of Dietary Life
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• v.17 no.3
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• pp.351-363
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• 2007

Previously, we analyzed for nutrition knowledge and the use of nutrition knowledge in the everyday lives of students in order to develop nutrition education programs that focus on desirable behavior change. From this, we found that female students desired to participate in nutrition education more than male students, and regarding their concerns for nutrition education, 73.2% of the females and 50.0% of the males displayed interest in 'obesity and the regulation of body weight'. Therefore, this study showed female students give more attention to the obesity and the regulation of body weight than male students(p=.000<.001). In addition, female students had higher interests($8.63{\pm}1.67$) than male students ($7.45{\pm}2.03$) in nutrition knowledge(p=.000<.001). By investigating the use of nutrition knowledge in everyday life, our research indicated that the actual use of nutrition knowledge was less. To encourage students to persue dietary lives addressing the concerns confirmed above, the following needed to occur. 1) Provide them nutrition information for the main processed foodstuffs encountered when dining out(breads, cakes, cookies, and carbonated beverage). 2) Teach them to read food nutrition labels. 3) Help them find a lifestyle connection through lasting self-management methods and the generation of social support. Accordingly, this required developing effective and practical nutrition education programs that considered regional characteristics and gender differences. The most important factors considered during nutrition education program development were the need for motivation and ongoing education by stage of change, rather than temporal education through specific problem analysis, in order that those being educated may bring about a change of behavior by themselves. Therefore, from this study, we have suggested the use of multilateral operating strategies for successful nutrition education. In addition the phase model of behavior change should be applied. Our programs were aimed at self owned nutritional management so that students could master their own methods for acquiring skills and enjoying dietary life. The research may be summed up as follows. First, the purpose of education at the recognition stage of change was to attempt motivation for nutrition improvement, by analyzing the problems such as food buying habit and the main purchasing viewpoints when dining out. Second, the purpose of education at the action stage of change was to help students acquire of concrete methods for behavior modification by linking the program to their home as well as to teachers with various activities that suited the situation at school. This was done by analyzing the processes and decisions pertaining to dining out the main processed foodstuffs and principal components, etc. through data and experimental practice. Third, the purpose of education for changing of habits and values, or the maintenance stage, was to investigate the various reasons that undesirable behaviors were induced, and then determine a lasting self-management method as well as how to generate social support. If the nutrition education program developed in this study is utilized on site, someone in the primary role as the nutrition educator and trained specifically in nutrition, can help induce the health promotion in the community as well as lasting dietary management, by executing a link with families in parallel with educating teaching staff and students' parents. In addition, this program can playa role in the government policies related to the health promotion for our youth who are the foundation of our nation and who can enhance our national competitive power.

• Journal of Korean Society of Transportation
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• v.23 no.1
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• pp.93-102
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• 2005

An Origin-Destination (O/D) is considered as one of the important information in route choices and trip assignments. A household interview survey is deemed to be the traditional and the most widely used method in making sample O/D and its conversion to the total O/D. Some researchers have studied to estimate dynamic O/D from the relationship between link volumes and trip assignment model. Nowadays, owing to the recent rapid spread of cellular phones. Location information of the cellular phone through the Base Station(BS) is considered as an alternative to O/D estimation. In this study, the methodology of generating BS-based O/D and the methodology of converting this O/D into an administrative district-based O/D are proposed. The information of GPS positions and cellular BS positions have acquired by establishing GPS equipment and cellular phone on taxies in Cheongju. Three weeks data are collected and used in estimating O/D by matching them on a digital map. Scatter diagram and sample correlation coefficients are used to investigate the similarity of the GPS-based O/D pattern among weeks, among days, and among times in day. The results show that there are few significant differences among weeks. But there is a difference in O/C pattern between weekday and weekend. Furthermore, there is a difference between morning peak and afternoon peak. Two methodologies are proposed to convert BS-based O/D into an administrative district-based O/D. The first one is to use the distribution pattern of GPS coordinates, the other is to use the coverage area of the BSs. To validate such converted O/D, GPS O/D is used as a true value. The statical analyses through scatter diagram, MAE and RMSE shows that there is few significant defference of pattern between the estimated BS-based O/D and GPS O/D. In the case of using only cellular information, the methodology using coverage area of the BSs is recommended for estimating O/D.