• The Journal of Korean Academy of Prosthodontics
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• v.43 no.2
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• pp.158-175
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• 2005

Statement of problem. Every effort has been continually made to obtain objectivity in measuring the longevity of fixed restorations, such as by establishing unified judgement standard for deciding success and adopting statistical method that analyzes the data of successful and failed cases at the same time. In Korea, however desired level of development has not to be made in this field yet. Purpose. This study, adopting California Dental Association (CDA) quality evaluation system, established objective standard for deciding success, and inferred the longevity of fixed restorations and their failure analysis through adopting Kaplan-Meier survival analysis. Material and method. In order to assess the longevity of flxed restorations serviced in Korea and causes of failure, a total of 1109 individuals (aged 15-74, 716 women and 393 men loaded with 2551 unit fixed restorations, and 1934 abutments) who lived in Kyung-In Province were examined and the findings were as follows : Results. 1. Length of service of fixed restorations serviced in Korea was 6.86$\pm$0.15 yr (mean), 5.5 yr (median), and the rate of success was 65.82% in 5 year survival, and 21.15% in 10 year survival. 2. When there was patient's need for replacing old prosthetics, longevity of fixed restorations was 7.51$\pm$0.27 yr (mean), 7 yr (median), and the rate of success was 61.08% in 5 year survival, and 17.57% in 10 year survival. 3. Longevity of fixed restorations was longest in the over-sixty age group(9.21$\pm$0.66) and that of the teen age group(3.39$\pm$0.28) was shortest (p<0.05). 4. Longevity of fixed restorations of women (7.38$\pm$0.18 years) was longer than that of men (6.00$\pm$0.26) (p<0.05). 5. As for the provider factor (such as unlicensed performers, university hospitals, and private clinic), there was no statistically significant difference in longevity of fixed restorations. 6. Defective margin (34.78%). periodontal disease (12.15%), periapical involvement (11.73%), was the most frequent causes of failure and poor esthetics group showed the longest life above all (p<0.05). Actual frequent causes of failure after removing old prosthetics were defective margin, periapical involvement, periodontal disease and uncemented restoration. In 75.67% of the cases, abutment state after removing old prosthetics was good enough for loading another prosthetics. 7. There was found to have statistically significant influence between longevity of single crown (6.35$\pm$0.20 yr) and that of 3 unit fixed restorations (7.60$\pm$0.30 y) (p<0.05). In each case the most frequent cause of failure was defective margin. 8. The number of cantilever pontic, pontic/abutment ratio, oral hygiene status were found to have no statistically significant influence on longevity of fixed restorations in all groups (p>0.05). 9. Longevity of fixed restorations made of non precious metal was longest (9.60$\pm$0.40 yr) semi precious and precious trailing behind(p<0.05). 10. Group function group (37.04%) and partial group function group (44.62%) were predominant in frequency but showed no correlation between them and among different types of occlusal plane and different types of occlusal surface (p>0.05). 11. Longevity of fixed restorations was longest in the centric interference group(9.35$\pm$0.62) (p<0.05) among different types of occlusal interference. Conclusion. We found that longevity of fixed restorations serviced in Korea is affected by age, gender and type of material, and that most frequent cause of failure is defective margin. In order to assess the accurate longevity of axed restorations, unified research design. overcoming inter-observer difference and establishing the objective research items are needed. Furthermore, it is thought that prospective approach through thorough study and regular follow-ups is needed just from the start of research. Nationwide detailed studies on length of service of fixed restorations manufactured in Korea are hoped to be conducted hereafter.

• Journal of the korean academy of Pediatric Dentistry
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• v.39 no.2
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• pp.111-119
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• 2012

The objectives of this study were to evaluate oral health status of children in multicultural families and compare oral health behaviors of multicultural mothers with those of ordinary Korean families. The mothers' social characters, oral health behaviors and oral health status of children were investigated so that the data from this study can be utilized in developing programs for oral health care promotion especially designed for multicultural families. The subjects were 135 pairs of multicultural mothers and their children who participated in the community programs in suburban areas of Ik-san city and 168 pairs of ordinary Korean mothers and their children residing in Ik-san city. The results were as follows : 1. The dft index and dfs index of multicultural subjects were 4.17 and 6.67, respectively, while ordinary Korean subjects were found to have 2.69 and 4.63($p$ <0.05). 2. The frequency of tooth brushing per day of children from multicultural families was lower than that of children from ordinary Korean families($p$ <0.01). 3. The ratio of practice of oral health behaviors of mothers from multicultural families was lower than that of mothers from ordinary Korean families($p$ <0.01). Tooth brushing instructions were the most frequently carried out by multicultural mothers, which was followed by teaching the importance of oral health, restriction of carbohydrates, and dental check-ups. Significant correlations were not detected between mothers'oral health behaviors and children's dental caries experiences($p$ >0.05).

• Sleep Medicine and Psychophysiology
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• v.12 no.1
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• pp.32-38
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• 2005

Objectives: Obstructive sleep apnea syndrome (OSAS) has drawn increasing attention as medical community has become to be aware of its co-morbidities and complications, especially cardiovascular complications and excessive daytime sleepiness with accident proneness. As of now, polysomnography is the standard tool to diagnose sleep apnea and estimate the treatment validity. However, its being rather expensive and inconvenient, alternate diagnostic tools have been proposed including wrist actigraphy. So far, actigraphies have been adopted usefully to field-survey sleep apnea prevalence. In this study, we attempted in a sleep laboratory setting to assess the supplemental value of actigraphy in diagnosing OSAS. Methods: This study was done at the Division of Sleep Studies, the Seoul National University Hospital. Thirty-seven clinically suspected cases of OSAS underwent the one-night polysomnography, simultaneously wearing an actigraphy on non-dominant wrist. We analyzed the data of 27 polysomnographically-proven OSAS patients (male：female 20： 7；age $47.6{\pm}12.9$ years old；age range 23 to 72 years) with no other sleep disorders. We calculated RDI (respiratory disturbance index) from the polysomnography data and FI (fragmentation index) from the actigraphy data. Pearson correlation was calculated in order to compare FI with RDI and to evaluate the supplemental diagnostic value of the actigraphy. Results: Mean total sleep time on polysomnography was $401.4{\pm}57.8\;min$ (range of 274.0 to 514.1 min). Mean RDI was $21.7{\pm}20.4/hour$. Mean FI was $21.9{\pm}13.0/hour$. RDI and FI showed significant correlation (r=0.55, p<0.01). Conclusions: Wrist actigraphy in OSAS patients generates a comparable outcome to polysomnography, in measuring the nocturnal sleep fragmentation. The actigraphy could be used supplementally in inpatients, outpatients, and field survey subjects, if polysomnography is unavailable or impossible. In follow-ups related with nasal CPAP (continuous positive airway pressure), upper airway surgery, and oral appliance in OSAS patients, the actigraphy might play a more dominant role in the future.

• Journal of Oral Medicine and Pain
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• v.31 no.3
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• pp.211-221
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• 2006

Purpose The aims of this study were to evaluate micro-tensile bond strength of composite resin bonded to dentin following high-speed rotary handpiece preparation or Er:YAG laser preparation with two different adhesive systems and to assess the influence of different Er:YAG laser energies on the micro-tensile bond strength. Materials and Methods In this study, 40 third morlars were used. Flat dentin specimans were obtained and randomly assigned to eight groups. Dentin surfaces were prepared with one of four cutting types: carbide bur, Er:YAG laser (2 W, 3 W and 4 W) and conditioned with two bonding systems, Scotchbond Multipurpose Plus (SM), Clearfil SE bond (SE) and composite resin-build ups were created. After storage for 24 hours, each specimen was serially sectioned perpendicular to the bonded surface to produce more than thirty slabs in each group. Micro-tensile bond strength test was performed at a crosshead speed of 1.0 mm/min. Micro-tensile bond strengths (${\mu}TBS$) were expressed as means$\pm$SD. Data were submitted to statistical analysis using two-way ANOVA, one-way ANOVA, Student-Newman-Keuls' multiple comparison test and t-test. Results and Conclusion 1. Regardless of bonding systems, the ${\mu}TBS$ according to cutting types were from highest to lowest : 3 W, 2 W, Bur, and 4 W. In addition, there was no significant difference between Bur and 4 W (p<0.001). 2. Regardless of cutting types, SM showed significantly higher ${\mu}TBS$ than SE (p<0.001). 3. Bonding to dentin conditioned with SM resulted in higher ${\mu}TBS$ for 3 W compared to Bur, 2 W, and 4 W. There was no significant difference between 2 W and Bur (p<0.001). 4. Bonding to dentin conditioned with SE resulted in higher ${\mu}TBS$ for 3 W compared to 2 W, 4 W, and Bur. Bur exhibited significant lower ${\mu}TBS$ than all other cutting types. There were no significant differences between 3 W, 2 W and between 4 W and Bur (p<0.001). 5. The ${\mu}TBS$ of laser cutting groups were shown in order from highest to lowest: 3 W, 2 W and 4 W in two bonding systems. There was no significant difference between 2 W and 3 W in SE (p<0.001). : The ${\mu}TBS$ of composite resin bonded dentin was significantly affected by interaction between the cutting type and bonding system. In the range of 2 W-3 W, cavity preparation of the Er:YAG laser seems to supply good adhesion of composite resin restoration no less than bur preparation. In particular, if you want to use the self-etching system, including Clearfil SE bond for the purpose of a simplification of the bonding procedures and prevention of adverse effects by excessive etching, an Er:YAG laser may offer better adhesion than a bur.

• Management & Information Systems Review
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• v.35 no.4
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• pp.251-268
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• 2016

The present study has the purpose of analyzing the relationship between entrepreneurial characteristics and success factors of small-scale start-up founders as well as the relationship between success factors and performances of start-up businesses. It is also aimed in this study to determine the structural effects of start-up founders' characteristic upon their performances and by thus, to provide those who prepare for and/or have been operating start-up business with suggestions for stable and successful start-up as well operation. The study resulted in the following outcomes: First, the analysis of the relationship between characteristics and success factors of start-up business found that the empirical characteristics of small-scale start-up business founders might influence every factor for their success including the financial conditions as well as management of shops, products and service. Their psychological characteristics, however, turned out to have influence upon the management of products and service only, but not upon the financial conditions and management of shops, a result implying that the higher desire and creativity small-scale start-up business founders have, the more probable the start-up businesses become successful. Second it was learned from the analysis of the relationship between success factors and performances of start-up businesses that such success factors of start-ups as financial conditions as well as management of shops, products and service could exercise impact upon their performances, signifying that the exact decision making of small-scale start-up founders might affect the performances of small-scale start-up businesses. Third, the analysis of the relationship between entrepreneurial characteristics and performances of start-up founders revealed that both empirical and psychological characteristics of start-up founders might have influence upon the performances of start-up businesses, leading to the conclusion that small-scale start-up founders could achieve higher performances in their start-up when they are highly aware of empirical and psychological characteristics for start-up as part of entrepreneurial characteristics.

• The Korean Journal of Emergency Medical Services
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• v.12 no.3
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• pp.87-98
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• 2008

Purpose : This study was designed to figure out the necessity of continuing basic CPR education for the higher grade students of elementary school. The assessment contents were knowledge, practice ability, precision level of CPR skills and continuation of the educational efficiency. Methods : Twenty two students of 4th and 5th grade of elementary school in K city in Chungcheongnam-do were recruited for this study. The study method was a control group of non-synchronized design. A preliminary study was done on October 27 in 2006. The main study was performed from February 14 to May 11 in 2007. The researcher adopted the method of Kyung-hui, Kang (1998) such as awareness, attitude and knowledge in control group, emergency medical technician test protocol, Anne/SkillReporter$^{(R)}$ in case of the basic CPR knowledge. Four times of measures were done in shortly after practicing CPR, 4 weeks after the education, 8 weeks after the education, and 12 weeks after the education. By using SPSS/PC+ (version 12.0), the researcher analyzed the collected data based on frequency, percentage, repeated measurement, ANOVA (analysis of variance), and sidak (multiple comparison - sidak). Results : 1) The confidence of people in the control group in terms of practicing CPR showed a statistically meaningful difference (t = 10.230, p = .000) before/after CPR education. Therefore, hypothesis No.1-1 was accepted. 2) The educational necessity of people in the control group showed no statistically meaningful difference (t = -1.695, p = 0.105) before/after CPR education. Therefore, hypothesis No.1-2 was rejected. 3) The knowledge points of people in the control group showed a statistically meaningful difference (t = -7.731, p = .000) before/after CPR education. Therefore, hypothesis No.2 was accepted. 4) The confidence of people in the control group in terms of practicing CRP showed no meaningful difference (F = 2.789, p = 0.072) as time passed. Therefore, hypothesis No.3 was rejected. 5) The knowledge of people in the control group showed a meaningful difference (F = 9.090, p = .000) as time passed. Therefore, hypothesis No.4 was accepted. 6) The capability of people in the control group in terms of practicing CPR showed a statistically meaningful difference (F = 42.795, p = .000) as time passed. Therefore, hypothesis No.5 was accepted. 7) The precision level of CPR skill of people in the control group showed a statistically meaningful difference (F = 25.198, p = .000) as time passed. Therefore, hypothesis No.6-1 was accepted. 8) The precision level of chest compression skill of people in the control group showed a statistically meaningful difference (F = 5.188, p = .003). Therefore, hypothesis No.6-2 was accepted. Conclusion : In a nutshell, CPR education for the 4th and 5th graders of elementary schools had an influence on their confidence in practicing CPR and on their knowledge. This study showed that as time passed. the educational effect declined in terms of knowledge point, capability of practicing CPR, and the precision level of CRP skill. The results of the study could be postulated into the fact that re-education within 8 weeks after the first education was essential to retaining the educational effect. Therefore, we need to vitalize the CPR education for elementary school students repeatedly on a regular basis in order to continue the educational effect after they were grown-ups and to make them play their roles as a first aider.

• Restorative Dentistry and Endodontics
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• v.31 no.4
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• pp.300-311
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• 2006

The purpose of this study is to evaluate prospectively the effect of different bonding systems and retention grooves on the clinical performance of resin restorations in non-carious cervical lesions (NCCLs). Thirty-nine healthy adults who had at least 2 NCCLs in their premolar areas were included in this study. One hundred and fifty teeth were equally assigned to six groups: (A) Scotchbond Multi-Purpose (SBMP, 3M ESPE, St. Paul, MN, USA, 4th generation bonding system) without retention grooves; (B) SBMP with retention grooves; (C) BC Plus (Vericom Co., Anyang, Gyeonggido, Korea, 5th generation bonding system) without retention grooves; (D) BC Plus with retention grooves; (E) Adper Prompt (3M ESPE, Seefeld, Germany, 6th generation bonding system) without retention grooves; (F) Adper Prompt with retention grooves. All cavities were filled with a hybrid composite resin. Denfil (Vericom Co., Anyang, Gyeonggido, Korea) by one operator. Restorations were evaluated at baseline and at 6-month recall, according to the modified USPHS (United States Public Health Service) criteria. Additionally, clinical photographs were taken and epoxy resin replicas were made for SEM evaluation. At 6-month recall, there were some differences in the number of alpha ratings among the experimental groups. But, despite the differences in the number of alpha ratings, there was no significant difference among the 3 adhesive systems (p < 0.05). There was also no significant difference between the groups with or without mechanical retention (p < 0.05). Follow-ups for longer periods than 6 months are needed to verify the clinical performance of different bonding systems and retention grooves.

• The Korean Journal of Physiology
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• v.2 no.2
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• pp.101-135
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• 1968

As physical fitness measured was muscle strength (hand grips, leg extention, back lift, and arm pull and thrust), skinfold thickness (5 different sites), circulatory function (resting heart rate and blood pressure), speed (kinesiological analysis during 100m sprint, record, maximal and final speed), motor function (50 meter dash, ball throwing, standing broad jump, and pull-ups), maximal aerobic power (maximum oxygen intake by field running method), muscle power (leg and arm by inertia ergometer), and general endurance (maximum endurance running time on the treadmill at the speed of 5 MPH and grade of 15.5%) of 1131 Korean children (boys 572, girls 559) aged of 6 to 17 years, who were randomly sampled from 24 primary, middle and high schools at the two districts of Seoul and KyungKi. The results are summarized as follows: 1) The status (height and weight) of the children was almost same as that of the previously reported Korean and Japanese children of same ages. 2) Muscle strength was a gained linearly with geting age in the boys and girls but there was a little improvement in girls aged of 13 years or more. 3) The mean skin fold thickness was increased linearly with geting ages in both sexes, but the girls from 12 to 17 years of age were increased rapidly, and maximum value was 17mm, while boys was 7.0 mm. 4) In the circulatory function, the resting heart rate was decreased, but the blood pressure was increased with ages in both sexes within the normal limits. 5) The maximum and final speed during 100 meter sprint increases with age in boys but girls who are 12 years old or older, were not improved any mere. The patterns of running were same in both sexes, and maximum speed reached at about 30 meters from starting line. 6) The motor function was increased with age in both sexes, but there was no improvement in 12 years of age or older girls. More over records of all functions except standing broad jump was less than those of Japanese in the same age, respectively. 7) The maximum oxygen intake (MOI) was increased considerably with ages and maximum values were 2.93 L/min (boys) and 2.09 L/min (girls) at the age of 17years. This result was almost same as that of the Japanese and Easter Island population, but the value was lower than that of Europe. The average of the maximum oxygen intake per kg body weight per minute from 9 to 17 years of age were around 53 ml in the boys and 42 ml in the girls. 8) Muscle power was increased linearly with ages in boys while there was relatively a little increment in girls. The maximum values of leg muscle in boys and girls at the 17 years of age were 0.168 and 0.088 horse power, respectively. 9) The maximum endurance running time was increased considerably from the age of 9 in boys, while there was no improvement in girls. The maximum values were 6.0 min and 1.8 min, respectively.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.35 no.6
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• pp.639-643
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• 2002

Water quality, bacterial phase and fish growth rate were analyzed in the process of artificial seed production of flounder (Paralichtys oliraceus) larvae to investigate the water quality in rearing tank using Ultra Filtration System (UES). Sand Filtration System (SFS) and Ultra Filtration System (Ins) were set up in the experimental group. For the analysis of water quality, pH, salinity, DO, SS, COD, $NH_{4}^{+},\;NO_{2}^{-},\;NO^-,\;DIN$ (dissolved inorganic nitrogen) and DU (dissolved inorganic phosphate) were measured. There was no data difference between SFS group and UES group in most analysis items, but the UEs group showed low salinity and low 55 values, such that salinity was $33.5\%_{\circ}$ in SES group and $30.2\%_{\circ}$ in WS group and 55 was 15.5 mL/L in SES group and 7.0 mL/L for UPS group. For changes in bacterial phase and TBC (Total Bacterial Counts), in SES group, 6$\times$10^{5}CFU/mL in seawater decreased to the ratio of about 116, and TBC, Genus Vibrio and bacteria in the Genus Acinetobacter and Genus Micrococcus sharply increased after nine days, while stable bacterial phase was maintained low in UES group during the experiment except for Genus Ajteromonas. In the growth of the larvae, fish length was 17.0 mm (SGR 14.0) in the SES group and 18.8 mm (SGR 14.3) in the UFS group. It is concluded that when water is supplied for artificial seed production with WS, stabilization of water quality condition and inhibition of bacterial multiplication are possible. When production environment becomes stable, stable growth of fish becomes possible by reduction of environmental stress.

• Journal of Preventive Medicine and Public Health
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• v.42 no.6
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• pp.386-391
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• 2009

Objectives : This cross-sectional study was performed to examine if the serum gamma-glutamyltransferase (GGT) level that is within its normal range is associated with the risk of type 2 diabetes and if the association between the waist hip ratio (WHR) and type 2 diabetes is different depending on the serum GGT levels. Methods : The study subjects were 23,436 persons aged 40 years or older and who participated in regular health check-ups at 11 hospitals (males: 5,821, females: 17,615). The gender-specific quintiles of the serum GGT and WHR were used to examine the associations with type 2 diabetes. Results : The serum GGT levels within their normal range were positively associated with type 2 diabetes only in women. The adjusted odds ratios (ORs) were 1.0, 1.0, 1.4, 2.1, and 2.5 according to the quintiles of the serum GGT ($p_{trend}$<0.01). The WHR was more strongly associated with the prevalence of diabetes among the women with a high-normal serum GGT level as compared with those with a low-normal serum GGT level (p for interaction=0.02). For example, the adjusted ORs for women with a low normal serum GGT level were 1.0, 1.2, 1.5, 2.2, and 2.4 according to the quintiles of the WHR, while those figures were 1.0, 2.4, 3.6, 5.0, and 8.3 among the women with a high normal serum GGT level. However, in men, the serum GGT was very weakly associated with type 2 diabetes and the association between the WHR and type 2 diabetes was not different depending on the serum GGT level. Conclusions : Serum GGT within its normal range was positively associated with type 2 diabetes, and central obesity was more strongly associated with the prevalence of type 2 diabetes when the serum GGT level was highnormal. However, these associations were observed only in women, which is different from the previous findings. The stronger relation between central obesity and type 2 diabetes among women with a high-normal serum GGT level can be useful for selecting a group that is at high risk for type 2 diabetes irregardless of whatever the underlying mechanism is.