• Journal of Korean society of Dental Hygiene
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• v.13 no.3
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• pp.387-393
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• 2013

Objectives : This study was carried out to investigate stepwise regression analysis on cervical abrasion & general characteristics, subjective oral health perception, habit related to oral health, and oral symptom. Methods : The study subjects were 2,158 workers in 23 industrial work places located in Gumi-si, Gyeongsangbuk-do Province from June 1 to July 1, 2012. As a result, the following conclusions were obtained. Results : 1. The cervical abrasion rate was high in men and older age group. 2. The cervical abrasion rate was high in a case of having not received scaling for the past one year. 3. The cervical abrasion rate was high in frequent tooth brushing. 4. The cervical abrasion rate was high in group having no bleeding in tooth and the gum. 5. The cervical abrasion rate was high in group having the cold symptom in teeth. 6. Excluding gum pain and bleeding, factors affecting tooth abrasion were gender, age, scaling over the past year, frequency of brushing a day and tooth sensitivity when cold food was ingested. 7. Gender and tooth sensitivity turned out to have negative(-) effect. age, scaling over the past year and frequency of brushing a day turned out to have positive(+) effect. Conclusions : Through this study, the best prevention method of cervical abrason is effective tooth brushing education and regular dental check up.

• Proceedings of the KIEE Conference
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• 1992.07b
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• pp.1123-1125
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• 1992

In this paper, a current fed type Push-Pull high frequency inverter which have used in the past, proposed self tunning circuit. Also, theoretical analysis introduced which use normalization, and a several characteristics or circuit is estimated. Further, a purposed control circuit based on self tunning system is confirmed to be performance by experiment.

• Journal of Aerospace System Engineering
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• v.6 no.2
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• pp.23-27
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• 2012

The evaluation of simulation models against ADS-33 quantitative rotorcraft handling qualities metrics has, in the past, been a time consuming effort, involving many individual analyses in both the time and frequency domains. Manual tuning of control system parameters to meet handling qualities and performance specifications has been cumbersome and complicated. Performing rigorous trade-off studies for numerous variations in the control system is too time consuming to be practicable. With the complex interaction of time- and frequency based specifications for the closed- and broken-loop responses, it is difficult to know if the design makes the most effective use of the available control power. The Control Designer's Unified Interface (CONDUIT) software makes possible rapid optimization and trade-offs of design configurations against handling qualities specifications.

• Journal of the Korean Home Economics Association
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• v.40 no.12
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• pp.85-108
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• 2002

The objectives of this study were to investigate the trend of the attitude and the behavior about consumer's internet premium advertisement and its application and the factors which influence on the attitude and the behavior about consumer's premium advertisement and its application; the demographic variables, internet communication-environment variables and variables in relation to consumer's premium advertisement application. For these purpose, the data collected two way: internet survey and questionnaire survey. The data used in this study included people who have looked an internet Premium Advertisement more than once during internet use. Major findings were as following: (1) The attitude of internet premium advertisement and its application could be described as the mean 34.16 md 24.61 separately(3.11 and 2.73 point on 5.00 points scale). The behavior of application about internet premium advertisement was measured as a behavior of application whether or not; application 18.7% and unapplication 81.3%. (2) The attitude of application about internet premium advertisement was significantly different according to age, joining frequency on internet, past experience of winning a premium, purchasing information search, interesting connection on the internet, the risk about the money loss and negative evaluation of other persons, the economical values of premiums, winning possibility, and preferable premiums. The behavior of application about internet premium advertisement, the behavior of application whether or not was significantly different according to sex, age, school career, a circuit speed, a period of using, joining frequency and a using place, past experience of winning a premium, purchasing information search, interesting connection on the internet, the risk about the negative evaluation of other persons, the economical values of premiums, winning possibility, and preferable premiums. (3) When looking at the influence of variables about the attitude of application about internet premium advertisement, the most influence variables was the past experience of winning a premium, and next was winning possibility, sex, the interest about the premiums which made the consumer want to apply, the economical values of premiums, the purpose of purchase information search and the using time. The explanation of those variables were 22.6%. As the result of the Logistic analysis, it was found that the frequency of the internet connection, the past experience of winning premiums, the risk about the outflow of credit information, interesting premiums, and premium advertisement were the most important variables to affect the possibility of the behavior of application about internet premium advertisement critically.

• Journal of Society of Preventive Korean Medicine
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• v.19 no.2
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• pp.13-22
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• 2015

Objective : The aim of this study was to review the use of Korean medicine (KM) or Complementary and Alternative Medicine (CAM) therapies among children with cerebral palsy (CP). Method : Literature searches were performed using Pudmed, CNKI, J-STAGE and four Korean databases. We investigated the frequency, types, predictors of the use of KM or CAM therapies used in children with CP. Results : Thirteen survey studies including use of KM or CAM among children with CP were selected - six Korean studies and seven overseas studies. The utilization rate of CAM among children with CP varied 26.8~56.0% according to the studies. CP children used KM or CAM more than other children with chronic disease. Acupuncture and Korean herbal medicine was the major treatment used in Korea, however physical manipulations such as massage, osteopathy and chiropractic were in high demand in western country. Disease severity of CP, use of CAM in the past by the parent or family member and high education of parent are the factors that significantly affect CAM utilization. Conclusion : Further studies on effectiveness and safety of KM therapies combined with conventional rehabilitation treatment would be required to expand the implementation of KM treatment for CP children.

• Journal of Korean Public Health Nursing
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• v.3 no.1
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• pp.5-17
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• 1989

The purpose of this study was to investigate the natural menopause age of middle-aged women in Korea and to analyse various factors affecting them. For the collection of date, 1,140 women aged between 45-54 were selected through stratified sampling technics in Seoul and at a rual area in Kyong KiProvince. They were interviewed from Nov. 1 through Dec. 31,1987 by use of questionnaires made after pilot study had been performed twice. Among them the final subjects for analysis were restricted to only those who had experienced menopause or irregular menstruation during the past one year, the number of which was total 410:206 in urban and 204 in rural area. For the analysis, menopause age was used as dependent variables while fertility variables, socio-economic variables, bio-physical varibles, and insight of life variables were classified as independent variables. Dependent variables such as menopause was tested and analysed by descriptive statistical methods(e.g., frequency, percentage, mean, $X^2-test.$ t-test, ANOVA). The relation between menopause age and independent variables was analysed by use of Pearson's correlation coefficients. For the analysis of various factors affecting menopause age, multiple stepwise regression method was used. The obtained results are summarized as follows: 1. The natural menopause age of Korean women were 47.2 mean age: it was 47.7 and 46.7 mean age in urban and rural area respectively, which revealed that the former was later then the latter by one year. And the recollective error on menopause starting age between the menopause group and the group who had experienced irregular menstruation during the past one year was 0.4-0.7 year. 2. The main factors affecting the menopause age were (1) the duration of marital life, (2) the duration of oral pill use, (3) insight of life and economic status, (4) educational background. (5) menarche, (6) usual menstruation amount, (7) electic charge. and (8) area. These factors. altogether, could explain $18.4\%$ of factors related with menopause, and they took the high percentage in the order mentioned.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.26 no.1
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• pp.1-10
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• 2016

Objectives: The aim of this study is to review the results of exposure to chemicals and to extremely low frequency(ELF) magnetic fields generated in wafer fabrication operations in the semiconductor industry. Methods: Exposure assessment studies of silicon wafer fab operations in the semiconductor industry were collected through an extensive literature review of articles reported until the end of 2015. The key words used in the literature search were "semiconductor industry", "wafer fab", "silicon wafer", and "clean room," both singly and in combination. Literature reporting on airborne chemicals and extremely low frequency(ELF) magnetic fields were collected and reviewed. Results and Conclusions: Major airborne hazardous agents assessed were several organic solvents and ethylene glycol ethers from Photolithography, arsenic from ion implantation and extremely low frequency magnetic fields from the overall fabrication processes. Most exposures to chemicals reported were found to be far below permissible exposure limits(PEL) (10% < PEL). Most of these results were from operators who handled processes in a well-controlled environment. In conclusion, we found a lack of results on exposure to hazardous agents, including chemicals and radiation, which are insufficient for use in the estimation of past exposure. The results we reviewed should be applied with great caution to associate chronic health effects.

• Korean Journal of Community Nutrition
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• v.10 no.3
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• pp.281-289
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• 2005

Hyperlipidemia and related heart disease will be growing public health problems as the population ages. It is therefore of great importance to identify modifiable risk factors. So this research investigated associations among life style, nutrient intake, and blood lipids in middle-aged men with borderline hyperlipidemia. Dietary intakes were assessed by food-frequency questionnaire and convenient method. The subject's histories of alcohol use and smoking were assessed via a questionnaire. Current smokers were classified as smokers, whereas past smokers and subjects who never smoked were classified as nonsmokers. With regard to alcohol intake, the subjects were stratified into drinkers and nondrinkers. In drinkers the frequency were measured. Frequency of alcohol intake and weight were associated with high blood lipids and blood pressure. The highest quartile of calcium intake had lower triglyceride concentration than did those in the lower three quartiles. High calcium intake was associated with low blood triglyceride concentration. These results suggest that healthy weight and high calcium intake and less alcohol intake can contribute to maintenance of healthy blood lipids in men.

• Plant Journal
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• v.4 no.3
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• pp.54-59
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• 2008

The resonance of boiler is caused by exciting force in the gas path and it generates the vibration by the harmony of boiler's dimensional factor. According to trending toward the boiler of increasing capacity and a bigger size, it has a problem of the vibration at back-pass heating surfaces. We can predict such vibrations as comparison between vortex frequency and gas column's natural frequency. We can't rely on the method for the past decades because of changing parameters, such as an allowable error, gas temperature, gas velocity, Strouhal number. We can reduce the vibration to use the seasoning effect and change the operating condition in coal fired boiler but it's not essential solution. When the vibration occurred in the model boiler, we must measures the acoustic pressure and frequency of places for considering the means. So far, we confirmed the problem from field measures and theoretical analysis about the acoustic vibration of boiler. We installed anti-acoustic baffle in a existing boiler to change the acoustic natural frequency at the cavity, which results in reducing the acoustic vibration. The first, we prove that the acoustic resonance is caused by harmonizing vortex shedding frequency of tube heat surface with acoustic natural frequency of cavity in the range of 650~750 MW loads. The second, the acoustic resonance at the back-pass heating surface has the third order of acoustic natural frequency at the second economizer. We install five anti-acoustic baffles at the second economizer to reducing the resonance. We confirm considerably reducing the acoustic vibration of boiler during the commercial boiler.

• Journal of Radiation Protection and Research
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• v.19 no.1
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• pp.51-68
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• 1994

It is good method to use frequency of chromosome aberration in Lymphocytes for a biological dosimetry in cases of accidental exposure to radiation. But in cases of past exposure, biological dosimetry is limited because the frequency of aberration decreases by time after exposure. To provide a basic data for estimation of past radiation exposure, the changing pattern of frequency of unstable chromosome aberration by time interval after exposure was studied. Observation was made on peripheral lymphocytes of 41 blood samples from 20 patients treated for uterine cervical carcinoma and endometrial carcinoma. The patients received 50.4Gy radiation to whole pelvis. Elapsed times after the completion of radiation therapy were 1 day, 3, 6, 9, 12, 24, 52, 104, 156, 208, 260 and 520 weeks. All the blood sample were microcultured. The Ydr, Qdr and Qdra were calculated from frequency of unstable aberration. Ydr did not decrease for 3 weeks after radiation therapy, and thereafter, decreased very rapidly and reached 0.05 at two years after radiation therapy and decreased very slowly until 5 years after radiation therapy. Relationship between unstable chromosome aberration and time interval after radiation therapy was described as $Ydr=0.259{\times}exp(-0.0429T)+0.0560{\times}exp(-0.00106T)$ (time in weeks) Qdr remained constant at 1.51 until 24 weeks after radiation therapy and then decreased to 1.17 at 52 weeks. Therafter, it did not change. Qdra remained constant at 1.10 for 12 weeks after radiation therapy and decreased to 0.81 at 52 weeks. Thereafter, it remained constant. Two superimposed exponential Ydr disappearance rate suggests that it is possible to calculate the past exposure dose. When the elapsed time after exposure is short, Qdr and Qdra are useful papameters for biological dosimetry for past radiation exposure.