• Journal of Positioning, Navigation, and Timing
• /
• v.12 no.3
• /
• pp.245-255
• /
• 2023

Time comparison techniques are necessary for generating and keeping Coordinated Universal Time (UTC) and distributing standard time clocks. Global Navigation Satellite System (GNSS) Common View, GNSS All-in-View, Two-Way Satellite Time and Frequency Transfer (TWSTFT), Very Long Baseline Interferometry (VLBI), optical fiber, and Network Time Protocol (NTP) based methods have been used for time comparison. In these methods, GNSS based time comparison techniques are widely used for time synchronization in critical national infrastructures and in common areas of application such as finance, military, and wireless communication. However, GNSS-based time comparison techniques are vulnerable to jamming or interference environments and it is difficult to respond to GNSS signal disconnection according to the international situation. In response, in this paper, Code-Division Multiple Access (CDMA) based All-to-All TWSTFT operation method is proposed. A software-based simulation platform also was designed for performance analysis in multi-TWSTFT signal environments. Furthermore, code and carrier measurement jitters were calculated in multi-signal environments using the designed simulation platform. By using the technique proposed in this paper, it is anticipated that the TWSTFT-based time comparison method will be used in various fields and satisfy high-performance requirements such as those of a GNSS master station and power plant network reference station.

• Journal of agricultural medicine and community health
• /
• v.22 no.1
• /
• pp.27-34
• /
• 1997

This study was performed to offer the fundamental data for preventing and controlling the cardiovascular diseases of rural community women. The number of 168 women aged 40 to 50s who live in Kumsan-gun, Chungnam were selected for analysis after medical examination by a Kumsan-gun health center during the period of November to December in 1996. Total cholesterol(TC), triglyceride(TG), high density lipoprotein cholesterol(HDL-C), blood pressure(BP), degree of obesity(BMI) and atherosclerosis index(AI) were measured and relation between these physical measurements to serum lipid levels were studied. The results were as follows; 1. Mean TC level, TG level, BP, BMI and AI were significantly increased with advancing age. 2. Mean TC level, TG level, BMI and AI of borderline BP group and hypertension group were significantly increased than those of normal BP group. 3. Mean TC level, TG level and AI of obesity group were significantly increased than those of normal BMI group. 4. Simple correlation analysis showed that the positive correlation between TC, TG, BP, BMI and AI, but the level of HDL-C was negative correlation with TG and AI. 5. In multiple regression analysis taking HDL-C level as the dependent variable and TG, TC, BP, BMI, Age AI as the independent variable, AI, TG, BMI, TC were significantly related to HDL-C.

• The Journal of Advanced Prosthodontics
• /
• v.7 no.3
• /
• pp.224-232
• /
• 2015

PURPOSE. The purpose of this study was to find out the effect of immediate dentin sealing (IDS) on bond strength of ceramic restoration under various thermocycling periods with DBA (dentin bonding agent system). MATERIALS AND METHODS. Fifty freshly extracted human mandibular third molars were divided into 5 groups (1 control and 4 experimental groups) of 10 teeth. We removed enamel layer of sound teeth and embedded them which will proceed to be IDS, using All Bond II. A thermocycling was applied to experimental groups for 1, 2, 7, 14 days respectively and was not applied to control group. IPS Empress II for ceramic was acid-etched with ceramic etchant (9.5% HF) and silane was applied. Each ceramic disc was bonded to specimens with Duo-link, dual curable resin cement by means of light curing for 100 seconds. After the cementation procedures, shear bond strength measurement and SEM analysis of the fractured surface were done. The data were analyzed with a one-way ANOVA and Tukey multiple comparison test (${\alpha}$=.05). RESULTS. There were no statistically significant differences between 4 experimental groups and control group, however the mean value started to decrease in group 7d, and group 14d showed the lowest mean bond strength in all groups. Also, group 7d and 14d showed distinct exposed dentin and collapsed hybrid layer was observed in SEM analysis. CONCLUSION. In the present study, it can be concluded that ceramic restorations like a laminate veneer restoration should be bonded using resin cement within one week after IDS procedure.

• Asian Pacific Journal of Cancer Prevention
• /
• v.17 no.sup3
• /
• pp.71-75
• /
• 2016

Pancreatic cancer is a leading cause of fatality worldwide. Several population studies have been conducted on genetic diagnosis of pancreatic cancer but the results from epidemiologic studies are very limited. CYP17A gene has a role in disease formation but its influence on pancreatic cancer is unclear. A polymorphism in the 5'UTR promoter region of CYP17A1-34T/C (A1/A2) has been associated with multiple cancers. The aim of the current study was to assess associations of this polymorphism and socio-demographic risk factors with pancreatic cancer. A total of 255 and 320 controls were enrolled in the study, and were genetically analyzed through PCR-RFLP. Statistical analysis was conducted with observed genotype frequencies and odds ratios (ORs) and 95% CIs were estimated using unconditional logistic regression. The impact of socio-demographic factors was accessed through Kaplen-Meir analysis. According to our results, the A2/A2 genotype was significantly associated with pancreatic cancer (OR=2.1, 95%CI = 1.3-3.5). Gender female (OR=2.6, 95%CI=1.8-3.7), age group 80s/80+ years (OR=2.2, 95% CI=1.2-4), smoking both former (OR=4.6, 95% CIs=2.5-8.8) and current (OR=3.6, 95% CI=2-6.7), and family history (OR=7.1; 95%CI = 4.6-11.4) were also found associated with increased risk. Current study suggests that along with established risk factors for pancreatic cancer CYP17A1-34T/C may play a role. However, on the basis of small sample size the argument cannot be fully endorsed and larger scale studies are recommended.

• Korean Journal of Childcare and Education
• /
• v.12 no.6
• /
• pp.79-102
• /
• 2016

The purpose of this study was to identify school adjustment groups by applying a Latent Profile Analysis(LPA) and to investigate the effects of children's emotional problems and study habits on determining the membership of these groups. LPA and multiple logistic regression were conducted using the data of 2,200 third-graders from the Korean Children and Youth Panel Study. The results are listed as follows. First, four school adjustment groups were identified: adjustment, approach to adjustment, maladjustment risk, and maladjustment group. Second, accomplishment value and mastery goal orientation were relatively strong predictors of membership of the school adjustment groups. Time management was also a significant variable that predicted the membership of maladjustment or the maladjustment-risk group. Third, attention problems and depression were the most consistent predictors of membership of maladjustment or the maladjustment-risk group. Physical symptoms and social withdrawal were also significant. Based on the results, implications for intervention to promote early school adjustment were discussed.

• Journal of Korean Society of Occupational and Environmental Hygiene
• /
• v.25 no.3
• /
• pp.418-427
• /
• 2015

Objectives: This study evaluated the association between work related characteristics and hypertension among white collar workers in Korea. Materials and methods: This study was based on the Third Korean Working Conditions Survey(KWCS) conducted in 2011 among workers 15 years of age or older. The total number of individuals included in the analysis was 10,365 white collar workers. Results: The prevalence rate of hypertension was 3.7% among men and 1.0% among women. In multiple logistic analysis the adjusted odds ratio showed statistically effective association to hypertension. For work related characteristics, 1.73 (95% confidence interval, 1.22-2.46) resulted for large-company workers compared with the small-company group, 2.14 (95% CI, 1.22-3.75) for the long working hours group (61 or above) compared with short working hours group(52 or below), 1.78(95% CI, 1.08-2.95) for night shift workers compared with day workers, and 1.54 (95% CI, 1.18-2.01) for high job stress workers compared with low job stress workers. Conclusions: This study showed that it is important for workers to manage their work environment in order to prevent hypertension by modifying their types of work.

• The Journal of Korean Academic Society of Nursing Education
• /
• v.9 no.1
• /
• pp.126-135
• /
• 2003

Purpose: The purposes of this study are as follows: Identifying the types of bullying; describing the relationship among social support, parent-adolescent communication and bullying types; identifying factors influencing the bullying. Method: 374 subjects were 5-6th grade students of two elementary schools in Daejeon. We collected the data from June 10 to October 29, 2002. The data were analyzed by using the frequency, ANOVA, pearson's correlation and stepwise multiple regression in the SPSS. Result: The 7 % of the subjects were found as bullies and another 23.8 % as victims, while 25.9 % were found as bully-victim group. The number of the victims in peer-support got less than in the normal or bully group. In the correlation analysis, the score of bullies, victims and bully-victim group were reversely-correlated with the social support. The score of victims was reversely-correlated with the mother-adolescent communication. In regression analysis, the social support influenced significant effects on both the bullies and victims. Conclusion: Findings indicated that the health professionals need to identify social support and parent-adolescent communication according to bullying types. Therefore, adequate approaches for the three independent groups of bullying are necessary.

• Journal of Fashion Business
• /
• v.18 no.6
• /
• pp.208-221
• /
• 2014

The purpose of this study was to investigate the effects of the hair style, and perceiver's generation on the perception of a high schoolgirl's image. A quasi-experimental method by questionnaire was used. The subjects were 253 high schoolgirls and their mothers living in Jinju. The data were analyzed by using frequency, factor analysis, Cronbach's alpha-reliability coefficient, three-way ANOVA, and Duncan's multiple ranges test. The high schoolgirl's image was derived in five dimensions by factor analysis: schoolgirl look, prettiness, individuality, activeness, and cuteness. In the image based on the hair length, it was assessed that the short cut and the bobbed hair styles looked more like school girls. And the short cut and long hair styles were considered as showing individuality. On the other hand, the bobbed hair style was assessed as cuter than styles of other lengths. For the bangs, the short bangs were found to more school-girl look and cuter than the long bangs. The mother group, whose ages were older than that of the other group, evaluated that the stimulative pictures had more school-girl look, individuality, prettiness, activeness and cuteness, compared to how the school girl group evaluated. It was shown that the generation gap produced different opinions about the stimulative pictures. Therefore hair style, bangs style, and difference in generations were found to be the variables affecting perception of high school girl image.

• Korean Journal of Human Ecology
• /
• v.18 no.1
• /
• pp.181-188
• /
• 2009

The purpose of this study is to analyze the brand choice behaviors of male and female college students in their twenties, to examine the differences in their information-searching activity to the type of the behaviors and shopping places for purchasing apparel products. The data were analyzed by Factor analysis, Ouster analysis, one-way ANOVA, Duncan's multiple range test. The results are as follows: 1. With regard to the brand choice behaviors of male and female college students in their twenties, two factors were produced as 'consumers' loyalty to brand' and 'brand switching behavior'. 2. The brand choice behaviors were classified into three groups as 'a brand-switching group', 'a loyalty-to-brand group', and 'an indifferent-to-brand group'. There were significant differences between the groups. 3. The results for demographic differences in terms of the brand choice behaviors showed that there was a significant difference in 'brand switching behaviors' by gender. 4. There were significant differences in the media for information search and the places for shopping apparel products in terms of the brand choice behaviors.

• International Journal of Costume and Fashion
• /
• v.4
• /
• pp.47-61
• /
• 2004

This study analyzed the buying patterns of American and Korean female college students in terms of criteria for clothing selection； store preferences； criteria for store selection； fashion information sources； expressions of customer dissatisfaction； purchasing frequency and motivations for purchasing clothes. The study was implemented through self-administered questionnaires which were back translated for validity. The samples consisted of 730 female college students majoring in the fields related to clothing and textiles： 310 U.S. and 412 Korean students. Likert scales were used for most measures with 1＝never or very unimportant and 5＝always or very important. Data were analyzed by factor analysis, analysis of covariance, Duncans multiple comparison, and t-test. Results are as follows： 1) Design factor was the most important criteria in clothing selection with no differences between country groups. There were, however, significant differences for psychological exhibition factors, practical and economic factors. 2) Both groups preferred specialty and department stores, with department stores more popular in Korea. 3) Merchandise was the most important store selection criterion and fashion magazines and self-experience were rated as the most important information sources for the both groups. 4) Korean group expressed their dissatisfaction with and observable problem with a product before purchase more often than U.S. group, but the U.S. group was more vocal about color loss or shrinkage after care procedures. 5) Some clear differences between the two countries emerged. Marketers targeting American consumers should pay more attention to practicality and service； to Korean consumers more symbolic meaning of products.