• The Journal of Korean Academy of Prosthodontics
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• v.33 no.2
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• pp.335-353
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• 1995

The purpose of this study was to the determine the optimal torques values to tighten the retaining screw. 3-different implant system tested were as follows : Branemark implant system$(3.75mmD{\times}100mm)$, Steri-Oss implant system$(3.8mmD{\times}10mm)$. One fixtures of each implant system was mounted into the epoxy resin block and abutment/superstructure complex was constructed. Eighty dental college students(male : 40, female : 40) of Chosun University were selected and were asked to tighten the retaining screws. Abutment/superstructure complex of each implant system was tightened to the maximum torque by use of hand-held screw driver, and then torque value was measured with torque value was measured with torque driver(Tohnichi torque driver, model 20 FTD, Tohnichi MFG, Co., LTD., Tokyo, Japan). Abutment/superstructure complex of each implant system was titghtened to each torque of 10 N-cm, 20 N-cm and 30 N-cm, and then the dynamic load(vertical & diagonal load) was applied to the abutment / superstructure complex. The gap between abutment/superstrure in each implant system was measured with 3-dimensional measuring microscope(model No. 850, Germany). The results were as follow : 1. Torque values according to the individual subjects showed wide range. 2. Torque values according to sex showed statistical significant difference. Those are as follows : in case of male, $9.38{\pm}2.93$ N-cm ; incase of female, $7.80{\pm}2.25$ N-cm. 3. Torque values according t implant systems showed statistical significant difference. Those are as follows : in ase of Branemark implant system, $6.54{\pm}1.54$ N-cm : in ase of Steri-Oss implant system, $10.1{\pm}2.88$ N-cm ; in case of IMZ implant system, $9.18{\pm}2.17$ N-cm. 4. The more torque value of tightening screw was increased, the less the gap was after the vertical and diagonal loading. 5. The gap after the diagonal loading was greater than that after the vertical loading. 6. The magnitude of gap between abutment/superstructure in order of IMZ, Steri-Oss, Branemark implant system after the verical and diagonal loading. 7. The gap under the diagonal loading after applying 30 N-cm torque showed no statistical significant difference in cases of the Branemark system and the Steri-Oss implant system but it showed significant different in case of the IMZ implant system.

• Management & Information Systems Review
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• v.31 no.2
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• pp.21-39
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• 2012

To examine how usage of social network services(SNS) can affect users' satisfaction through their involvement to SNS. This study first explored the usage motives on the SNS by reviewing previous studies which are from the perspectives of usage and gratification theory. The structural equation modeling(SEM) approach was used to validate the model and Lisrel was used to analyze 306 data which were collected from college students who have SNS using experiences. The results showed that the motives of information seeking and self-expression have no significant influence on affective involvement to SNS and other hypotheses were all accepted. In order to investigate the relationship of usage motives-involvement-satisfaction between different genders, path analysis in male group and female group were done respectively. The results showed that in the case of male group, the motivation of information seeking, entertainment, and self-expression have positive effect on affective involvement, while only the entertainment motive can increase the cognitive involvement. In the case of female group, socializing motive and entertainment motive have positive effect on both affective involvement and cognitive involvement, but the information seeking motive and self-expression motive can not influence the formulation of emotion in SNS.

• Journal of Digital Convergence
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• v.20 no.3
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• pp.407-413
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• 2022

Existing clothing recommendation systems remain at the level of showing appropriate photos when a user selects a type of clothing he or she likes after entering his or her own body size or body size. When a user purchases clothing using such recommendation systems, there are many cases in which it does not fit or does not fit the user's body size. In this study, to solve these problems of existing clothing recommendation systems, a system was implemented in which the user receives not only size but also skin tone and recommends clothing suitable for the user's body size as well as skin tone. In this system, clothing size information obtained through web crawling was periodically stored in a database for eight male tops to recommend clothing, and the entire pixel of the clothing image was analyzed to extract color text values. In order to confirm the performance of this system, a survey was conducted on 100 male college students, and the satisfaction level was 70%. Most of the reasons for not being satisfied are that the recommended clothing is limited, so it is judged that it is necessary to expand the target clothing in the future.

• The korean journal of orthodontics
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• v.25 no.3 s.50
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• pp.311-321
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• 1995

This study was undertaken to investigate the distribution of the chewing side preference and variations in the maximum bite force and facial morphology according to chewing side preference since unilateral chewing may cause morphologic and functional anomalies. 50 dental students who had no signs or symptoms of masticatory system and Angle's Class I relationship in posterior segments were selected, and divided into two groups, that is, 25 in bilateral chewing group(19 male and 6 female) and 25 in unilateral chewing group(10 male and 15 female). Maximum bite force was estimated ana posteroanterior cephalogram were measured ana statistically analyzed. The results were as follows : 1. Their were more students with bilateral chewing side preference($68\%$) and unilateral chewing side group consisted of right side preference($68\%$) and left side preference($32\%$). 2. There was no significant difference in the strength of max. bite force between the right and left side in bilateral chewing group. The bite force of the chewing side nab greater in the unilateral chewing group but less in the non-chewing side compared to those of bilateral chewing group with Bo significant difference. Max. bite force of chewing side was greater than that of non-chewing side in the unilateral chewing group(Female p<0.05). Max. bite force of males was about twice in that of females in both groups(p<0.05). Max. bite force of chewing side of the unilateral chewing group was similar to that of the bilateral chewing group, but that of non-chewing side was less than that of the bilateral chewing group. 3. In comparison of the facial morphology, there was no statistically significant difference in the size between the right and left side of the bilateral chewing group and between chewing and non-chewing side of the unilateral chewing group.

• Korean Journal of Culture and Social Issue
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• v.17 no.1
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• pp.81-113
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• 2011

This study investigates leisure activity, involvement and self-concept in cyberspace of various age groups of adolescents. A total of 1,388 students (elementary school=337, middle school=326, high school=361, university=364, consisting of 696 male and 692 female) participated in the study. The results are as follows. First, although the vast majority of adolescents (96.9%) had a computer at home, majority of adolescents visited Internet cafe. Second, 70.3% of adolescents visited Internet cafe to play Internet games, followed by engaging in information search, chatting, and participated in cyber community. Third, on average adolescents spent 5.43 hours per week playing Internet games, with more males playing Internet games than female adolescents. As for information search, the weekly average was 2.60 hours, with university students spending more time than the other groups. As for chatting, the weekly average was 1.69 hours, with no significant differences among the groups. The weekly average of Internet use was 9.65 hours, with older groups spending more time. The weekly average use of computer was 10.91 hours, with older groups spending more time and more males using more computer than females. Fourth, as for self-concept in cyberspace, elementary and middle school students reported that they had fun, while high school and university students reported that they were the same as in the regular daily life. In addition, adolescents reported that they spent leisure activity in cyberspace and they become a fictional character in cyberspace. Fifth, when they played Internet games, regardless of age and gender, adolescents reported that they had fun, followed by that they were absorbed, that they became aggressive, and that they were the same as in the regular daily life. Sixth, when they chatted on Internet, regardless of age and gender, adolescents reported that they had fun, followed by that they were not interested, that they were the same as in the regular daily life, and that they do not chat on Internet. Seventh, when they interacted with their friends on Internet, regardless of age and gender, majority of adolescents reported that they had fun, followed by that they conversed, that they were the same as in the regular daily life, and that they felt closer. These results indicate that Korean adolescents view Internet as a place to spend their leisure time and that they enjoyed spending time on Internet.

• The Journal of Korean Academy of Prosthodontics
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• v.46 no.2
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• pp.175-184
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• 2008

Purpose: This study was designed to investigate the fitness of adjustable dental impression trays on the Chinese and the Japanese. Material and methods: Initial design of the adjustable dental trays was developed from the results of the dental arch size of Korean adults. This design was applied to the CAD-CAM process in order to create tray model samples. Simple silicon-base molds were then replicated based on these sample models. Polyurethane injection into the silicon- base molds completed the process of creating a large number of test products. 60 Chinese dental students (male:30, female:30) from the Shanghai Second Medical University and 60 Japanese alumni from the Kumamoto high school (male:30, female:30) were selected for taking irreversible hydrocolloid impression with these trays. The width and length of the impression body were measured on several measuring points by Vernier caliper. The results were analyzed statistically to evaluate the fitness of the trays. Results: 1. Uniform impression material thickness was achieved on the Chinese and Japanese by controlling the width of the tray using stops and beveled guides. The material thickness was generally within the range of 3 mm to 6 mm. 2. In the maxillary tray of the Chinese, average thickness of the impression material of the labial vestibule of the incisal teeth was 6.2 mm, the canine was 5.9 mm and the midpalatal part 10.5 mm and the posterior palatal part 9.7 mm. These were relatively large values. 3. In the mandibular tray of the Chinese, average length of the impression material of the lingual vestibule of first, second premolar contact point was 8.9 mm, the incisal teeth was 7.8 mm and thickness of the labial part of canine was 6.8 mm and premolars 7.0 mm. These were relatively large values. 4. In the maxillary tray of the Japanese, average thickness of the impression material of the labial vestibule of the incisal teeth was 7.4 mm, the canine was 7.7 mm and the midpalatal part 9.1 mm. These were relatively large values. 5. In the mandibular tray of the Japanese, average thickness of the impression material of the labial vestibule of first, second premolar contact point was 8.4 mm, and thickness of the labial part of canine was 7.4 mm. These were relatively large values. Conclusion: This adjustable dental tray shows good accuracy to Korean because it was designed by the analysis of the dental arch size of Korean adult model. With this result, it can be applied to Chinese and Japanese, we can take more easy and accurate dental impressions.

• Journal of Korean society of Dental Hygiene
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• v.3 no.1
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• pp.25-43
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• 2003

In Korea, changes in children's diet patterns accelerate their physical growth and development: frequent snacking has been presumed to be a major cause of increasing dental caries. The present study attempts to clarify the relationship between the physical development of growing children and their tooth decay. For this purpose, 632 six-grade children in 4 elementary school located in Urban(Seoul) and Rural(Po-gok, Yang-In) were classified into three groups based on the Weight Length Index(WLI), known to reflect the nutritional conditions of school-age children, and the relationship was analyzed between each group and the variables considered to be related with dental caries. The result is as follows: The average weight and height of the male is $44.88{\pm}10.89$ kg, $148.49{\pm}7.33$ cm and female is $43.35{\pm}9.60$ kg, $149.23{\pm}6.73$ cm, respectively, which are in the similar level with the Korean Physical Standard. The classification of the children by the WLI reveals a relatively high distribution of over-weighted child ren - 212 persons, 335% of the entire population. The DMFT Index was a little high in the rural area(3.15 teeth in urban and 3.31, in rural). Among the groups of children classified by the WLI, the over-weight group have the highest DMFT index(3.69 teeth). The relationship between the frequency of taking in basic nutrients and the DMFT index is also found: the relationship is not evident in case of the foods containing rich calcium, protein, as well as fruits and vegetables. But, in the protein-rich food, higher frequency of its intake means significantly lower DMFT index in the normal-weight group of the urban children. In case of carbohydrate, higher frequency of its intake means significantly higher DMFT index in all the groups of the rural children. The DMFT index has some correlations with the relevant variables: the index has a positive correlation with the frequency of snacking, and a negative correlation with the economic status. That is, the higher the frequency of snacking is, and the lower the economic status is, the higher the DMFT index may be. In the logistic multiple regression analysis conducted with the presence of DMFT as a dependent variable, only the frequency of tooth brushing is turned to be a variable affecting the presence of either decayed, missing, or filled teeth. Based on the above result, the variables affecting the DMFT index are a time spent on eating, frequency of intake of protein and carbohydrate for a week, frequency of snacking, regular dental check-ups, preventive behaviors for oral health(fluoride gargling, tooth brusing after each meal, proper tooth brushing method). These variables have a relationship with the DMFT index, but the degree is somewhat different between the groups classified either by the region or by the WLI. Therefore, appropriate nutrition management should be conducted according to the individual's nutritional conditions when the services like nutritional education are provided based on the closely-examined characteristics of each target group. And, at the same time, oral health education should be strengthened, and its importance should also be emphasized so that people can pay attention to their own oral health.

• Journal of Korean Ophthalmic Optics Society
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• v.6 no.2
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• pp.99-104
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• 2001

This study surveyed common sense of testing eye vision, feeling of own vision and wearing glasses, and method of wearing glasses using questionnaire for 625 primary student(male 322, female 303) live in Iksan city, Jeon buk Province. The question about the selection of testing vision office answered ophthalmic optics only 12.6% by common sense but 38.8% among testing vision students had been checked the visual acuity in ophthalmic optics. 40% student of all answerer have a poor vision by self-evaluation testing and realized when they look far vision is 46.4% among the poor vision answerer, look black board is 26.0%, look monitor is 18.4%, and reading is 9.9%. 46% answerer of the subjective poor vision who tested eye vision by self-evaluation did not correct eye vision. 48.7% answerer among uncorrect eye vision is because of having no chance to test. The question of effect in wearing glasses answered that the 48% of a1l answerer will be worse the visual acuity, the other is getting better and unchanged eye vision by common sense. The question about how looks like glasses wearer answered that the 45.8% answerer is uncomfortable appearance by common sense. 32.3% answerer of the glasses wearer became a failure wearer because glasses was uncomfortable to fit primary student.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.5
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• pp.3139-3147
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• 2015

The aim of this study was to investigate the condition surrounding attempted suicide and related factors among middle and high school students in Korea. Methods : Data from 72,435 participants of 2013 Korea Youth Risk Behavior Web-based Based Survey were analyzed. Statistical analyses were conducted on weighted data using SPSS 21 software to account for the complex sampling designs. Results : Complex samples logistic regression analysis, school level, socioeconomic status, drinking alcohol, drug use, experience of school bullying were associated with an increased proportion of attempted suicide for boys and girls. Particularly, male students was associated with living type. Conclusion : The results of this study highlight the important of developing a program that focuses on enhancing suicidal prevention & respect life program with life skills program, to effectively reduce the likelihood of attempted suicide among adolescents in Korea.

• Toxicological Research
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• v.14 no.4
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• pp.515-523
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• 1998

Oxidative stress by reactive oxygen species (ROS) damages cellular DNA, RNA, proteins, lipids and others causing various diseases such as cancer, arthritis, and heart diseases. 8-Hydroxyguanine (8-OHG) is one of the products formed from DNA or RNA damaged by ROS. Since high amounts of 8-OHG can be excreted in urine, it may serve as a potential biomarker indicating the level of oxidative damage to nucleic acids. Residents in industrial area with severe air pollution are expected to be affected by higher level of oxidative stress from pollutants like polyaromatic hydrocarbons (PAHs), etc. Smokers are also expected to be damaged by higher level of oxidative stress from cigarette smoke components like PAHs than non-smokers. To examine if the determination of the urinary concentration of 8-OHG could be used as exposure biomarker for the oxidative stress caused by air-pollutants, this study was performed to determine and compare the urinary concentrations of 8-OHG in smokers and non-smokers, or non-polluted area residents and polluted area residents. Urine samples were collected and purified by a strong cation exchange and cellulose partition column, then analyzed by HPLC with electrochemical detector at 600 ㎷ potential. Concentrations of urinary 8-OHG in non-smokers and smokers of Seoul area college male students were determined as 15.12$\pm$9.68 (ng/mg creatinine) and 34.72$\pm$11.72 (ng/mg creatinine), respectively, showing significantly higher level of 8-OHG in smokers than in non-smokers. Urine samples of elementary school students were collected from Sokcho area, which is known to be non-polluted, and 3 representative polluted areas; Yocheon industrial area, Ulsan urban and Ulsan industrial area. The concentrations of 8-OHG in these samples were 12.42$\pm$8.27 (ng/ mg creatinine, Sokcho), 22.55$\pm$9.12 (ng/mg creatinine, Yocheon), 17.41$\pm$2.30 (ng/mg creatinine, Ulsan urban), 55.04$\pm$39.73 (ng/mg creatinine, Ulsan industrial). Thus, samples from polluted area tend to have higher level of 8-OHG and the levels of Yocheon and Ulsan industrial area were significantly higher than that of Sokcho area. The results indicate that the residents of polluted industrial area or smokers are more severely exposed to oxidative stress probably caused by air pollutants like PAHs. Thus, the determination of urinary 8-OHG concentration could be used as biomarker for the extent of body exposure to oxidative stress caused by various pollutants.