• The korean journal of orthodontics
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• v.40 no.5
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• pp.294-303
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• 2010

Objective: This study was designed to measure the surface roughness at the slot floor of various ceramic brackets. Methods: One kind of stainless steel bracket ($Succes^{(R)}$), two kinds of monocrystalline brackets (Inspire $Ice^{(R)}$, $Perfect^{(R)}$) and two kinds of polycrystalline brackets (Crystalline $V^{(R)}$, $Invu^{(R)}$) were examined. Atomic force microscopy (AFM) was used to measure the surface roughness of each bracket. Data acquisition and processing were performed using $SPIP^{TM}$. Results: The differences in values of Sa, Sq, and Sz in $Invu^{(R)}$ and Inspire $Ice^{(R)}$ were not statistically different from the control group $Succes^{(R)}$. The values of Sa, Sq, and Sz of $Perfect^{(R)}$ and Crystalline $V^{(R)}$ were greater than those of $Succes^{(R)}$. Differences of all the Sa, Sq, and Sz values between $Perfect^{(R)}$ and Crystalline $V^{(R)}$ were not statistically significant. Conclusions: It is concluded that the slot surfaces of $Succes^{(R)}$, Inspire $Ice^{(R)}$, and $Invu^{(R)}$ were smooth compared to those of Crystalline $V^{(R)}$ and $Perfect^{(R)}$.

• Radiation Oncology Journal
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• v.23 no.1
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• pp.1-8
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• 2005

Purpose : The objective of this study was to determine whether the expressions of the two components of DNA-dependent protein kinase, Ku70 and DNA-PKcs, influence the response to radiotherapy (RT) and outcome of treatment of non-disseminated nasopharyngeal carcinoma (NPC) in patients who received definitive RT. Materials and Methods : Sixty-six patients with NPC who were treated with radiotherapy alone or with concurrent chemotherapy between June 1995 and December 2001 were divided into groups based on the levels of immunoreactivity for Ku70 and DNA-PKcs in pretreatment biopsy specimens. The over-expression of Ku70 or DNA-PKcs groups Included patients whose biopsy specimens showed at least 50% immunopositive tumor cells; patients in which less than 50% of the tumor cells in the biopsy tissues were immunopositive were placed in the low Ku70 and DNA-PKcs groups. The immunoreactivities for Ku70 and DNA-PKcs were retrospectively compared with the sensitivity of the tumor to radiation and the patterns of therapy failure. Univariate analyses were peformed to determine the prognostic factors that influenced locoregional control of NPC. Results : The five-year locoregional control rate was significantly higher in the low Ku70 group (Ku(-)) (85%) than in the high Ku70 group (Ku(+)) (42%) (p=0.0042). However, there were no differences in the metastases-free survival rates between the two groups (Ku70 (+), 82%; Ku70 (-), 78%; p=0.8672). Univariate analysis indicated that the over-expression of Ku70 surpassed other well-known predictive clinocopathologic parameters as an Independent prognostic factor for locoregionai control. Eighteen of 22 patients who had locoregional recurrences of the tumor displayed an over-expression of Ku70. No significant association was found between the level of DNA-PKcs expression and the clinical outcome. Conclusion : Our data suggest that the level of Ku70 expression can be used as a molecular marker to predict the response to RT and the locoregional control after RT and concurrent chemotherapy in patients with non-disseminated NPC.

• Korea journal of population studies
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• v.14 no.1
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• pp.55-69
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• 1991

The objective of the study is to figure out the status of reproductive health and general characteristics related to maternal health for Korean-Americans living in Los Angeles. We collected data from the married women who wanted no more additional child birth and were attending the Family Planning Clinic of Koryo Health Foundation in Los Angeles during 1988. There were 494 women met the eligibility requirement for this study. The results are summarized below. 1. In the age distribution of the women who desired no more additional child birth, women 30-34 age group constituted the largest proportion at 36.6 percent ; the mean age of women was 35.1915.55. The mean number of child birth was 1.77, and the proportion of the women by number of child birth were 35.2 percent for one children, 50.1 percent for two children 10.5 percent for three children, and 2.6 percent for four children. All of the women experienced pregnancy at least once, and mean number of pregnancy was 3.42. The mean number of total experience of induced abortion was 1.56. and 76.7 percent of these women had experience with induced abortions. To prevent further pregnancies, 90.1 percent of the women were utilizing the contraceptive methods, and the highest proportion by the contraceptive methods was condoms(53.7%), 9.3 percent in spermicides, 8.7 percent in IUDs, 8.7 percent in rhythm method, and 6.9 percent in oral pills. 2. The mean age of women at each stage of reproductive life cycle were 14.74 years at time of menarche, 24.55 years at time of marriage, 26.60 years at time of the first child birth, and 28.75 years at time of the last child birth. In age distribution of the women by birth cohort (Group I : birth cohort 1940-1954, Group H : birth cohort 1955-1970), the mean menar-cheal age of the women was 14.96 years in group I , and 14.53 years in group H . Mean age at time of marriage was 25.01 years in group I and 24.08 years in group H . Mean child birth age of the women by birth cohort was 27.19 years In group I and 26.01 years in Group II for the first child birth and 30.07 years in group I and 27.45 years in group II for the last child birth. The total length of reproductive life cycle from menarche to menopause (presumed to be at 49 of age years) was 34.26 years. The len-gth of phase I (from menarche to marriage) was 9.81 years, while phase H (marriage to first birth) was 2.05 years, and phase Ill (first birth to last birth) was 2. 15 years, and the last phase of reproductive life cycle, phase IV (last birth to menopause) was 20.25 years. The proportion of each phase 10 total length of reproductive life cycle was 28.6 percent, 6.0 percent 6.3 percent, and 59.t percent respectively. In the tendency of each phase in reproductive life cycle by birth cohort (group I , U ), the length of phase I, II , III of birth cohort group II was diminished in comparison with those of birth cohort group I , but the length of phase IV was extended by 2.38 years. 3. Among the women, the mean number of total pregnancy by birth cohort group was 2.01 in group I and 1.10 in Group II, and mean number of child birth was 1.97 in group I and 1.58 in group II. In terms of pregnancy was-tage rate by birth cohort group, among the total pregnancy of birth cohort group I , 51.8 percent of the cases resulted in induced abortions or spontaneous abortions whils 48.2 percent resulted in live births, and 42.2 percent or total pregnancy in group II resulted in pregnancy wastage and 57.8 percent of the cases resulted in live births.

• Journal of dental hygiene science
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• v.17 no.6
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• pp.501-507
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• 2017

The shortage of dental hygienists has been a long-standing problem in Korea. Small-scaled dental clinics suffer from a lack of dental hygienists, who seem to prefer working at large-scaled dental clinics. The purpose of this study was to confirm the differences in the working conditions according to the scales of dental clinics. We collected the working information registered via job advertisements through the web-sites of Korean Dental Hygienists Association, Dental Jobs, and Nurse Jobs from July to August 2016. The results were as follows: 96.7% of the advertisements wanted regular workers, while the proportion of part-time workers was the highest (34.8%) in the group with less than 3 employees. The average workdays per week was $5.32{\pm}0.55$ days, and the group with less than 3 employees had significantly longer workdays than the other groups. The daily working time was $8.99{\pm}0.44$ hours, and there was no difference among the groups. Night overtime hours were needed by 54.4%, 45.0%, and 31.3% of the groups with of the groups with 4~7 employees, more than 8 employees, and less than 3 employees, respectively. Information regarding annual leave (60.5%), monthly leave (63.9%), half a day off (32.4%) and vacations (43.1%) were presented in the job advertisements, and these proportions were significantly higher by the group with more than 8 employees. Information on overtime pay (14.4%), night-work pay (13.4%), incentives (34.1%), lunches (60.2%), vacation bonuses (33.8%), and self-development (20.4%) were presented in job advertisements. The group with 4~7 employees had significantly higher proportions in severance pay, vacation bonuses, self-development, and major national insurance. It is necessary to consider the improvement of working conditions, diversity of working styles, and welfare of dental hygienists, and it is suggested that small dental clinics provide more precise working conditions.

• Journal of dental hygiene science
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• v.17 no.6
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• pp.487-494
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• 2017

There is little evidence on the effects of environmental tobacco smoke (ETS) on prevalence of periodontal disease. The aims of this study were to explore the trends of prevalence of periodontal disease and types of exposure to smoke, including ETS according to the survey year, identify factors affecting periodontal disease, and compare the effect size of periodontal disease between active smokers and secondhand smokers. Data on 11,643 individuals were obtained from the fourth and fifth Korean National Health and Nutritional Examination Surveys. Information on exposure to ETS at home and work was self-reported. Severity of periodontal disease was evaluated using the community periodontal index. A multivariate logistic regression analysis was performed to model periodontal disease using types of smoking and the survey year. Overall, the prevalence of periodontal disease was 26.0% (n=3,029) and about 9% of the study population were secondhand smokers. The prevalence of periodontal disease among smokers was significantly increased according to smoking types by year. Active smokers showed a statistically significant adjusted odds ratio (aOR) for having periodontal disease except in the year 2007, whereas secondhand smokers had significant associations only in 2010 (aOR, 1.68; 95% confidence interval, 1.05 to 2.70) compared to non-smokers. For secondhand smokers, the statistical relationship of predicting periodontal disease was weaker than that of active smokers. However, ETS should separately be considered as an important risk factor for periodontal disease. This study suggested the need for further investigation of the impact of ETS on prevalence of periodontal disease using in-depth research designs and objective measurements for assessing periodontal disease and ETS.

• Korea journal of population studies
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• v.16 no.2
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• pp.84-110
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• 1993

This study aims at identifying the recent change in marriage behaviors in Korea. The data used here is the vital statistics compiled from the vital registration system of which registration form is put on one from together with the civil registration form. According to the results of this analysis, since 1970 the number of marriages has steadily increased from about 300, 000 in the former of 1970s to about 400, 000 in the latter of 1980s, appproximately coincided with the change in population size at the marriageable age span. The few exceptions that can be seen in the 1970s seem to result from the impact of social upheavals during 1950s; since the birth cohorts affected by the low fertility during the Korean war and the post-war baby-boom generations chracterized by the high fertility entered the marriage market in the 1970s. However, the marriage rate shows a little increase from around 7 in the former of 1970s to around 9 in the latter of 1980s, indicating that the marriage prevalence has been more or less inconsiderably changed during this period. It is also found that the proportion of remarriage to the total marriages has increased to around 10 per cent in 1989, while decreasing that of first marriage. This fact can be attributable to the higher prevalence of divorces and the collapsing of the Confucianism ethic which contributed to expediting the remarriage of widows. Although this proportion is insignificant compared with that of the of more developed countries, it is not difficult to say that the proportion of remarriages will continue to increase in future. The age first at first marriage(AFM) which directly affects the span exposed to the risks pregnancy has increased to the age about 28 for male and about 25 for female in recent years. However, big difference in AFM between urban and rural areas has narrowed, resultant from the increasing involuntary postponement of marriage of rural young population who have met difficulties in seeking their bride or bridegroom in rural areas characterized by the heavy out-migration of young, particularly female, population. The present study shows the reverse relationship between AFM and educational attainment; i.e, the higher the educational attainment the lower the AFM. The conditions which are taken into considerations were the class and the family in the past time but which are, educational attainment, job and personal characteristics. With regard to the age condition, in recent years the male prefers the female younger than himself on the average by 3 years and vice versa, which is reduced form 4-5 years in beginning of 1970s. The age difference bride and bridegroom tends to decrease with the educational attainment increase. This may be attributable to the fact that the persons with the higher educational attainment prefer the love marriage and hence are more likely to choose their counterparts in the about same age. The education condition is characterized by the bridegroom having the higher educational level than bride. It is also significant to note that the proportion of love marriage has increased, whereas that of traditional arranged marriage has decreased. This is true in the urban areas than the rural areas, indicating that rights as well as responsibilities for marriage have been handed over the young population from their parents. In conclusion, the change in the marriage behaviors in Korea are characterized by increasing tendency for the postponement of first marriage, higher prevalences of divorces and a result remarriages, increase of love marriages, narrowing age difference between bride and bridegroom, etc. which are the main results of rapid industrization, increase in educational and economic activity opportunities and change in the ideals of marriages during the past decades. These phenomena prevailing in Korean society would affect not only the family structure that will become less proliferiated but the population size and structure. The most important is that the changes in marriage behaviors of Koreans and their impact on the society with respect to norms, values, morals, of individual and family in the social aspect, change in population size and structure in the demograpic aspects, and economic development in the economic aspects should be integrated into the plannings towards to the future.

• 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).

• Korean Security Journal
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• no.15
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• pp.29-50
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• 2008

Many countries throughout the world have enacted laws on terrorism in the light of the changes that time has brought to them, geographical features, cultural values, and environmental elements. Especially some advanced European nations prescribe the definition of terrorism, the purpose of terrorism, the behavior of terrorism, and the types of crimes related to terrorism and so on for the following reason that it is more vital for the authorities concerned to investigate and punish terrorists after the rise of terrorism. In this regard, this paper analyzes legislative countermoves against terrorists of advanced countries such as France, Germany, and England and through this sheds light on the need of future anti-terrorism bills. The legislative basic guidelines directly to manipulate future terrors based on theories derived from this study could be summarized as follows. In the first place, providing laws on direct investigative power and harsher punishment to those involved in terrorism is a prerequisite for social security and thus the presidential directive of the state anti-terrorism action guidelines just deals with administrative measures without any effective response to terrorism. Hence it is urgent to make anti-terrorism bill concerning investigation and punishment of terrorists. In the second place, it is associated with the objectives of terror. The expression "all sorts of" stated in Korean law is so quite unclear that it can not fulfill the required conditions for naming it "crime". Comprehending provisoes of the crime that meets the purpose of the terrorists is necessary in order to investigate and inflict punishment on them. Therefore, it is advisable to establish specific and precise principles such as political, social, ideological, and religious purpose of terrorists in the bill. In the third place, to meet the flow of times of technicalization, informatization, such provisoes as destruction of electronic data system, crimes related to nuclear materials, purchases of weapons by terrorists, tax administration for prohibition of sale, and arson should be considered in terror bill. In the fourth place, nonselective attack toward unspecified individuals has become a serious issue in our society. Terrorists leave poisonous foods or beverages to crowded place or dump toxic chemicals into river intentionally. Therefore more strict regulations must be included in terror bill to prevent possible terrorist attacks.

• Korean Security Journal
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• no.53
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• pp.63-79
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• 2017

Defence Security Command is the only military intelligence and investigation agency which is in charge of safeguarding military information and investigating specific crimes such as subversion and disloyalty in military. While the presidential security provided by Defence Security Command, along with Presidential Security Service(PSS) and the police, forms one of three pillars sustaining presidential security, its works and activities have been rarely known to the public due to the military confidentiality. This study looks into some data specialized into the presidential security among works of Defense Security Command by using various resources such as biographies of key people, media reports, and public materials. It reviews the presidential security works in a historical sense that the works have developed and changed in accordance with the historical changes of Defense Security Command, which was rooted in Counter-Intelligence Corps (Teukmubudae in Korean) in 1948 and leads to the present. The study findings are as follows. First, when the Korean War broke out in 1950 and since then the South Korea was under the threat of the North Korean armed forces and left wing forces, Counter-Intelligence Corps(Bangcheopdudae in Korean) took the lead in presidential security more than the police who was in charge of it. Secondly, even after the Presidential Security Office has founded in 1963, the role of the military on presidential security has been extended by changing its titles from Counter-Intelligence Corps to Army Security corps to Armed Forces Security Command. It has developed their provision of presidential security based on the experience at the president Rhee regime when they could successfully guard the president Rhee and the important government members. Third, since the re-establishment into Defence Security Command in 1990, it has added more security services and strengthened its legal basis. With the excellent expertise, it played a pivotal role in the G20 and other state-level events. After the establishment of the Moon Jaeinin government, its function has been reduced or abolished by the National Defense Reform Act. However, the presidential security field has been strengthening by improving security capabilities through reinforcing the organization. This strengthening of the security capacity is not only effective in coping with the current confrontation situation with the hostile North Korean regime, but also is important and necessary in conducting constant monitoring of the military movement and security-threat factors within military during the national security events.

• The Korean Journal of Quaternary Research
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• v.19 no.1
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• pp.1-17
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• 2005

This study aims to study the distribution and formation age of Quaternary deposits in the downstream of Yeongsan Estuarine River, encompassing Muan, Illo and Donggang counties. For this purpose the authors examine several borehole data, and step trench survey for excellent profiles was studied in connection with grain size population and magnetic susceptibility. As a result, it is interpreted that the coastal plain of the Yeongsan River was formed by sea level rise after Last Glacial Maximum(LGM). The fore edge/escarpment of coastal terraces distributed 7-10 m asl is assumed to be formed during the last glacial period, while the coastal terraces distributed above 7-10m asl formed during MIS 5a. In addition, the fore edge/escarpment of coastal terraces distributed above 15 m asl is presumed to be have been formed during the stadial of last interglacial period, while the formation age of coastal terraces distributed above 15m(asl) is assumed to be MIS 5e. This formation age can be estimated by the coastal terrace ages of the southeastern coast of Korean Peninsula. The characteristics of Quaternary deposits linked to paleolithic culture will eventually lead to the reconstruction of ecosystem environment of paleolithic peoples.