• Korean Journal of Health Education and Promotion
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• v.27 no.1
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• pp.61-69
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• 2010

Objectives: The aim of this study was to examine socioeconomic inequalities in oral health and to investigate the extent to which socioeconomic disparities in oral health are attenuated by oral health related consciousness and behaviors. Methods: We used data from the third 2006 Korea National Oral Health Survey(KNOHS) and a total of 3,457 subjects aged over 18 years were analyzed. The dependent variable was periodontal conditions which is devided into dichotomy, that is, health and ill-health, using the Community Periodontal Index(CPI) in KNOHS. Socioeconomic status(SES) were measured by educational attainment, income and residential area. Age, gender, oral health consciousness(self-assessed oral health status, concern about oral health and self-perceived dental treatment needs and behaviors(brushing, use of dental floss and dental visits) were adjusted in binary logistic regression analysis. Results and Conclusion: The results show that oral health consciousness and behaviors do not mediate the relationship between SES and periodontal health and there might be limitations to attenuate socioeconomic disparities in oral health only by changing of either oral health consciousness or(and) behaviors. Our findings suggest that more definite oral health policies and dental health education among adults with lower education will need in order to improve oral health.

• The Journal of Korean Medicine
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• v.28 no.2 s.70
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• pp.13-21
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• 2007

Objective : Halitosis, or bad breath, is a common concern for many people. The aim of this study was to investigate clinical characteristics of halitosis patients and correlation with their various associated elements. Methods: We surveyed 169 halitosis patients by reviewing questionnaires from the Halitosis Clinic in the Hospital of Oriental Medicine, Kyunghee University from January 2004 to March 2006. The questionnaires contained various items including sex, age, history of smoking and alcohol intake, duration of symptoms in a week, time and condition of severe halitosis, suggestive origin of halitosis, taste abnormality, oral hygiene, self-assessed halitosis severity, dry mouth, postnasal drip, tonsillolith, globus pharyngeus, reflux sensation, too much gas and Winkel tongue coating index. Volatile sulfur compounds were measured with a $Halimeter^{\circledR}$. Results : The halitosis patients actively carried out management methods such as non-smoking, moderation in drink, teeth brushing and tongue scraping in order to decrease their oral malodor. Tongue coating significantly affected the $Halimeter^{\circledR}$ reading score, and tongue coating and dry mouth significantly affected self-assessed halitosis severity. Conclusions: Our results suggest that tongue coating and dry mouth should be treated to improve satisfaction in halitosis patients.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.1798-1803
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• 2003

Surface and edge finishing processes are important technological operations of in parts machining. Quality of the finished parts directly affect the performance of the whole product. Especially, edge quality, which depends on burr control, is extremely important. Burrs are undesirable projections of the material beyond the edge of the workpiece. A number of deburring processes have been developed such as barreling, brushing, chemical methods etc. But, there are only few publications in the area of applying ultrasonics to deburring. When ultrasonic vibration propagates in the liquid medium, a large number of bubbles are formed. These bubbles generate an extremely strong force, which can be used to remove burrs. Cavitation is used as a term to describe the erosion of parts caused by the action of cavities in liquid. The object of this study is to analyze the effects of ultrasonic cavitation in the deburring process. For this purpose, we introduce a new ultrasonic cavitation method, which efficiently removes the burrs. Experimental parameters to verify the deburring effects of ultrasonic cavitations are ultrasonic power, amplitude, distant of the transducer from the workpiece, deburring time and abrasive. It has been shown that deburring with ultrasonic cavitation in water is effective to burrs.

• Korean Journal of Materials Research
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• v.17 no.11
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• pp.580-586
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• 2007

To enhance the reliability of a newly designed reciprocating compressor applied in a domestic compressor, accelerated life tests were developed using new definitions of the sample size and the $B_1$ life index. In $1^{st}$ accelerated life testing, the compressor was locked due to the fracture of the suction reed valve. The failure modes and mechanisms of the suction reed valve in the accelerated tests were found to be similar to that of the failed product in the field. The root cause of the failure was the overlap between the suction reed valve and the valve plate in the suction port. The missing parameters in the design phase were modified by expanding the trespan size, introducing tumbling process, changing the material and thickness for the valve, introducing a ball peening and brushing process for the valve plate. In $2^{nd}$ accelerated life testing, the compressor was locked due to the interference between the crank shaft and thrust washer. The corrective plan was to heat treat the crank shaft. The $B_1$ life of the compressor improved from 1.5 to 12.9 years.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.2
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• pp.233-239
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• 2016

This study compared and analyzed the tooth brushing time per day and dental caries in 1-13-year-old children in the stage of the completion of their permanent teeth based on the 6th primitive at data of objective National Health Nutrition Survey. The results show a meaningful difference between the DMFT and dental caries experience. In particular, the group with a lower toothbrushing rate after lunch generally have a higher incidence of dental caries.

• Journal of Korean society of Dental Hygiene
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• v.14 no.1
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• pp.17-24
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• 2014

Objectives : The purpose of this study was to investigate cognition on oral health education and dental caries preventive effect in kindergartens and child care facilities. Methods : A self-reported questionnaire was completed by 260 teachers in kindergartens and nursery facility in Daejeon from January to February, 2013. Except incomplete answers, 248 questionnaires were analyzed by using the statistical package SPSS WIN 18.0. Results : High intention to participate in oral health education was shown in the teachers who experienced the oral health education. Dental caries preventive effect included correct tooth brushing, fluoride dentifrice, fluoride mouth rinse, and use of xylitol. The teachers agreed that the fluoride mouth rinses would help good oral health in the children. Conclusions : Teachers in kindergartens and nursery facility are the most important persons in childhood oral health care. So it is necessary to provide the continuing standardized education for the teachers systematically.

• Journal of Korean Society of Steel Construction
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• v.12 no.2 s.45
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• pp.167-175
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• 2000

An experimental research to evaluate the slip coefficient of high-strength slip-critical-type bolt connection of weathering steel plate has been performed in this paper. Experiments were performed with several surface conditions such as clean mill scale with hand or power brush cleaning, shot blast cleaned, inorganic zinc primer coated, and weather coated surfaces. Also, the relaxation of bolt clamping force was estimated during 500 hours. It was ascertained from the experiments that slip coefficients are greater than 0.40 in all faying surface conditions except mill scale surface with power brushing. The quantify of relaxation depended on the surface conditions and was $3{\sim}8%$, i.e., less than 10%.

• Fire Science and Engineering
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• v.22 no.5
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• pp.61-66
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• 2008

In this research, gel compounds containing thermochromic ingredients were manufactured and evaluated to prevent the transition hazards of fire and explosion, which they are one of the methods for detecting abnormal conditions caused by overheating of special materials early. And also, compounds of viscoelastic and brushing types were manufactured as the kind and content of raw materials, and manufacturing process to enlarge the application for overheat-detecting targets. Test methods were conducted as chromism test, viscosity profile, starting time of thermochromism, and FT-IR analysis. Thermochromic gel materials exhibit chromism properties that can detect abnormal conditions effectively, and then they are possible to various applications.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.10a
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• pp.250-253
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• 2002

The operation of surface and edge finishing is the last and essential process of parts machining, because a product is completed as an assembly. Therefore, the quality of the finished parts has a direct effect upon the performance of the product. Especially, the edge quality depending on the burr control process is very important. A number of deburring processes have been developed for macro burrs such as barreling, brushing, chemical methods, etc. However, micro burr removal when piercing a very thin plate is very difficult, because this badly deteriorates the surface quality of the processed part. When ultrasonic wave is propagated in liquids, it forms an infinitude of micro bubbles. These bubbles generate extremely strong force, which removes micro burrs. In ultrasonic micro deburring, the problem is that burrs are not removed completely, because only components of the explosive force directly act on the burrs, which is not enough. An attempt was made to remove the burrs using ultrasonic vibration in water with SiC as an abrasive agent. Because of the abrasive, smoother edges have been achieved. There are many control parameters in ultrasonic deburring such as abrasive size, ultrasonic frequency and amplitude, distance between tool and workpiece, tilt angle of workpiece etc. This study focuses on how distance and tilt angle influence deburring effect. A number of experiments for these parameters have been carried out, and then the effect of each parameter analyzed.

• Journal of Korean society of Dental Hygiene
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• v.5 no.1
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• pp.53-62
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• 2005

To prepare basic data for oral health promotion of high school students through the survey of the recognition of oral health care, a questionnaire survey was conducted for 268 students. Statistical analysis was conducted using the SPSS 11.5 with ${\chi}^2$-test, fisher's exact test, t-test and logistic regression. The obtained results were as follows 1. The average of the high school student's oral health knowledge was $13.12{\pm}2.06$. Statistically school girls were higher(pE0.05) than school boy's oral health knowledge(male: 12.91, female: 13.35), tooth brushing frequency(male: 4times or more-15.4%, female: 4times or more-29.8%), and preventive dental visit(male: 8.1%, female: 17.5%). 2. More than 70% of high school students was concerned about oral health. According to the self-judgement of oral health, more than 50% of them was answered that they wasn't sure of oral health. 3. Only 13% of high school students received oral health education and 80% of them recognized oral health manpower's education needs. 4. The logistic regression analysis illustrated that high school student's preventive dental visit was independently associated with the self-judgement of oral health. The odds ratio was 3.0 and statistically significant.