• Journal of Korean society of Dental Hygiene
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• v.17 no.2
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• pp.181-191
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• 2017

Objectives: The objective of the study was to investigate the use of dental hygiene devices in Korean adolescents. Methods: The study subjects were 70,362 adolescents in 800 schools who completed the 2015 Korean Youth Risk Behavior Web-based survey. Dependent variables included usage of dental floss, interdental brushes and mouthwash solutions. Independent variables included demographic characteristics of the subjects, health state and behaviors, and oral health behaviors and experience of oral diseases. Results: The related factors of usage of dental hygiene devices included gender, where females showed higher usage (OR=1.10) compared to males, father and mother's level of education where usage was higher in above university graduates (OR=1.20, OR=1.14) compared to less than high school graduation, economic status where usage was higherin high and middle (OR=1.93, OR=1.26) compared to low, vigorous physical activity where usage was higher in those who responded yes (OR=1.35) compared to no, subjective weight recognition where usage was higher in normal (OR=1.07) compared to under weight, sleep time where usage was higher in enough (OR=1.12) compared to not enough, number of toothbrushing (day) where usage was higher in 2 times or over 3 times (OR=1.35, OR=1.75) compared to below 1, oral health education experience (OR=1.10), sealant experience (OR=1.17) and scaling experience (OR=1.45) where usage was higher in those who responded yes compared to no, school where usage was lower in high school (OR=0.64) compared to middle school, residential type where usage was lower in rural area (OR=0.74) compared to metropolitan area, living form where usage was lower in other (OR=0.77), compared to with family, smoking (OR=0.93), and alcohol drinking (OR=0.90) where usage was lower in those who engage in the activities compared to those who didn't, BMI where usage was lower in normal (OR=0.87) and over weight (OR=0.98) compared to under weight. Conclusions: To expand the use of dental hygiene devices in the adolescents, it is necessary to improve the continuing education program for need and motivation of dental hygiene device usage.

• Journal of Preventive Medicine and Public Health
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• v.26 no.1 s.41
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• pp.147-164
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• 1993

A study has been conducted on developing questionnaires to serve as on site diagnostic tools for the early detection of neuropsychiatric impairment among workers chronically exposed to low-level organic solvents. Two drafts of tentative questionnaires have been developed as follows; several question items were selected from questionnaires which were administered to workers exposed to organic solvents in previous studios and were grouped into each symptom category based on the presence of its association using Guttman scaling method, then these selected items were reviewed by neuropsychiatry specialists. The final draft of the questionnaire (total symptom score=36) was developed by selecting 33 question items which had more than a 0.88 Guttman coefficient of reproducibility in each symptom category from a pilot study in which these tentative questionnaires were administered to workers manufacturing soles. Three plants using organic solvents and one plant never using organic solvents as a control group were selected to test the reliability and validity of the developed questionnaires. The major organic solvent in the workplace environment detected by a personal air sampler and GC/MSD nab toluene. The concentration of toluene in air from the department using organic solvent was statistically different from that of the department never using organic solvent. The concentration of toluene from almost all of the workplace did not exceed the allowable level. There was no statistically significant difference between the concentration of urinary hippuric acid from the workers of the department using organic solvent and that of the department never using it. Total symptom score of the plant never using organic solvents was 9.8 and those of the three plants using organic solvents were 15.6, 14.7, and 13,7 respectively. In order to evaluate the validity of the questionnaires, the workers from two different departments of the plant in which usage of organic solvents are totally dofferemt were compared. The total symptom score was 17.8 for workers of the department using organic solvent and 13.5 for the department never using organic solvent and scores of each symptom group between exposure and non-exposure group also showed statistically significant difference. The finding that total symptom score of the exposure group increased as the duration of employment increased indirectly suggests the usefulness of the developed questionnaire to assess the health effects of chronic exposure to organic solvents. The correlation coefficient, which was calculated to evaluate the test-retest reliability, was 0.581 (p=0.001). The coefficient of Crohnbach which reflects the internal consistency of the questionnaire was 0.91. In conclusion, the reliabilty of the questionnaire was well maintained over the time lapse between the two administrations of the questionnaire and despite the seasonal difference.

• Journal of Korean society of Dental Hygiene
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• v.12 no.1
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• pp.201-212
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• 2012

Objectives : The purpose of this study was to examine about workers' oral health status and oral health behavior practice. Methods : Questionnaire survey was carried out targeting 331 workers within the industrial complex of Jeonju city in 2011. As a result of surveying and analyzing workers' oral health status, habit related to oral health, activity restriction, which is oral disease phase, and oral health practice level by using SPSSWIN 12.0. Results : 1. Workers' experience of visiting dental hospital(clinic) for the past one year was indicated to be the highest with 64.9% in the working period with 10 years-under 20 years(p<0.001). Experience of scaling was indicated to be averagely 38.8%. 2. The oral health status perceived by workers was the highest with 40.5% in 'having something abnormal'. A problem was the highest with 28.0% in 'dental caries'. A cause was indicated to be 42.6% in 'because of being naturally weak in tooth or the gum.' The biggest reason for having failed to receive the dental treatment at a proper time was indicated to be the highest with 24.8% in 'because of feeling burdensome about dental expense. '3. 58.4% of male workers were smoking. The use of dental hygiene device was the highest with 40.6% in mouth-rinse. 4. Absence caused by oral disease was indicated to be the highest with 13.8% in the household income in more than 3,500,000won, thereby having shown the significant difference(p<0.05). Early leaving was indicated to be the highest 13.9% in more than 50s age, thereby having shown the significant difference(p<0.05). Also, as for factors of absence and early leaving, a pain was the highest with 64.7%. 5. Workers' oral health practice level was the highest with 2.85 points in 'Brushing teeth before going to bed'. Conclusions : Synthesizing these findings, the oral management could be known to be made negligently in the workers with the older age, the lower academic background, and the lower income. The institutional foundation is considered to be necessary for which the oral health education can be efficiently performed in addition to a need of periodic oral examination for these classes.

• Journal of Korean society of Dental Hygiene
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• v.7 no.4
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• pp.569-582
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• 2007

The author aims at first securing basic material required for developing and operating proper oral health care education programs though making an investigation into the undergraduates of S College of Education on the actual status of oral health care and perceptions of oral health care education. The obtained results were as follows 1. In the actual status of oral care based on whether or not they have experiences in taking oral health care education, undergraduates with teeth brushing for more than three minutes a time were found to be 25.9% and 15.7% respectively according to the existence and nonexistence of experiences in the education(pM0.020), and undergraduates with teeth brushing in a circular motion was found to be 64.7% and 51.7% respectively, showing statistically significant differences(pM0.015). 2. In the actual status of preventative oral care according to whether or not they have experiences in taking oral care education, degrees of awareness of the usefulness of dental cleansers among the undergraduates were found to be 37.6% and 21.5% respectively according to the existence and nonexistence of experiences in the education(pM0.001), undergraduates with experiences in scaling were found to be 51.8% and 34.9% respectively(pM0.002) and undergraduates with experiences in having dental sealants were found to be 26.5% and 16.9%(pM0.031), showing statistically significant differences. 3. In the survey on perceptions of oral health care according to the existence and nonexistence of experiences in oral health care education, it was revealed that the case that they indicated 'the necessity of oral health care education' was 87.1% and 64.0% respectively according to the existence and nonexistence of the experience(pM0.000), and undergraduates intended to 'participate in oral care education for students(at mid and high schools and so on) after being teachers' were 77.6% and 65.7% respectively, showing statistically significant differences(pM0.011). 4. In general characteristics according to awareness of the necessity of cultivating oral health professionals, groups with awareness of the necessity consisted of 31.8% of freshmen and juniors(pM0.001), 55.69b of female undergraduates(pM0.001), 80.8% of non-smokers(pM0.012), 38.9% of large city residents(pM0.002) and 32.3% of undergraduates living in their own houses (pM0.028), showing statistically significant differences.

• Korean Journal of Environmental Biology
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• v.34 no.3
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• pp.169-176
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• 2016

Although chemical fertilizers have a quick effect and broad applicability to agricultural fields, they have caused many problems like increasing soil acidity or decreasing soil organic matters. Environmental-friendly agriculture has been attempted in various ways such as organic agriculture, natural farming, low input and sustainable agriculture. The common interest of all environmental-friendly systems is to decrease burden to agricultural environment by low input of agricultural labor and materials. This study was conducted to estimate overwintering capacity and genetic distance among Chinese Milk Vetch (Astragalus sinicus, CMV) collections based on morphological characteristics and AFLP (Amplified fragment length polymorphism) analysis. Furthermore, the effect of CMV as green manure was observed in mix-cultured paddy fields with rice, sesame and sweet-potato. An another objective of this study was also to compare the pattern of weed occurrence in paddy fields with or without CMV and different rice transplanting times. The CMV collected from Paju district in central region of Korea was successively occurring through self-reseeding without artificial management. However, there was no noticeable difference in growth habit between Paju native CMV and introduced CMV from China which is currently used in farm fields. On the basis of multi-dimensional scaling and tree analyses, there are no significant difference of agricultural growth characteristics among Paju and chinese collections only excepting leaf angle and root length. The flowering time of Gurye collection was fast for 1 week as compared to other collections. AFLP that was commonly used for plant classfication, was applied to exam the genetic variation of CMV collections. Total 579 PCR products and 336 polymorphic fragments were generated using 8 primer pairs.

• The Journal of the Korea Contents Association
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• v.12 no.11
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• pp.258-266
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• 2012

This study was conducted to investigate the differences between smokers and non-smokers' oral hygiene and college students' smoking awareness. The survey was carried out based on the 260 college students enrolled in four-year universities located in Kyungbuk, Daegu, Gangwon-do. Collected date used the SPSS 17.0 to perform the frequency and cross-analysis. 1. The daily smoking amounts of less than half pack and the smoking duration of more than 1 year and less than 3 years were to be the highest. The initiation of smoking was triggered by the curiosity and the proximal social environment. The reason of smoking was to relieve stress and habitual smoking respectively. 2. There was a significant difference between smokers and non-smokers' tooth brushing time, regular dentist visit, recent dental admission, the purpose of dental visits, scaling and oral health education. 3. There was a significant difference between smokers and non-smokers' awareness of oral hygiene in the subjective oral hygiene status. 4. There was a significant difference between smokers and non-smokers' awareness towards the impact of second-hand, after meal and one or two cigarette smoking. Based on the above results, smokers lack the awareness of smoking and oral hygiene compared to non-smokers. Therefore, the activation and the development of programs for the smoking and oral hygiene education targeting college students are considered to be necessary.

• Ocean and Polar Research
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• v.38 no.2
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• pp.115-128
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• 2016

This study examined the relationship between macrobenthic distribution patterns and environmental factors in salt marsh vegetation in Donggeomdo, Ganghwa on the west coast of Korea. Nine stations were fixed on a transect across the salt marsh vegetation, and field sampling was carried out monthly from July 1997 to June 1998. A total of 38 species of macrobenthos were recorded: each of faunal groups, 13 (34.2%) Arthropoda, 12 (31.6%) Polychaeta, 8 (21.1%) Mollusca, and 5 (13.2%) others. The mean density was $2,659individuals/m^2$, with a mean biomass of $178.6gWWt/m^2$. Mollusca dominated in terms of abundance and biomass, with a mean density of $2,172individuals/m^2$ (81.7%) and a mean biomass of $131.9gWWt/m^2$ (73.9%). The number of species decreased in winter (January-February), while mean density increased in the spring (May-June). The biomass was relatively in Summer and Fall (July-November), than any other season. The number of species was high in pure stands of Suaeda japonica in the lower salt marsh vegetation, and the mean density and biomass were high in mixed halophyte communities in the middle salt marsh vegetation. Two Mollusca, the bivalve Glauconome chinensis and gastropod Assiminea lutea, were dominant. The densities of these two species were high in mixed halophyte communities in the middle salt marsh vegetation. Non-metric multi-dimensional scaling (nMDS) showed that the study area could be divided into four groups corresponding to the vertical distribution of tidal levels and halophytes. Spearman's rank correlation revealed that the distribution patterns and community structure of macrobenthos were related to environment variables such as salinity of the substrates, exposure time, and grain size compositions of the sediment in the salt marsh vegetation. Particularly, the distribution and density of some dominant species showed differences along the vertical distributions of halophytes.

• Journal of the Microelectronics and Packaging Society
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• v.12 no.2 s.35
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• pp.167-174
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• 2005

Smaller size and higher integration of electronic components make smaller gap between metal conducting layers in electronic package. Under harsh environmental conditions (high temperature/humidity), electronic component respond to applied voltages by electrochemically ionization of metal and metal filament formation, which lead to short failure and this phenomenon is termed electrochemical migration(ECM). In this work, printed circuit board(PCB) is used for determination of ECM characteristics. Copper leads of PCB are soldered by eutectic solder alloys. Insulation breakdown time is measured at $85^{\circ}C,\;85{\%}RH$. CAF is the main mechanism of ECM at PCB. Pb is more susceptible to CAF rather than Sn, which corresponds well to the corrosion resistance of solder materials in aqueous environment. Polarization tests in chloride or chloride-free solutions fur pure metal and eutectic solder alloys are performed to understand ECM characteristics. Lifetime results show well defined log-normal distribution which resulted in biased voltage factor(n=2) by voltage scaling. Details on migration mechanism and lifetime statistics will be presented and discussed.

• Journal of Periodontal and Implant Science
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• v.30 no.1
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• pp.145-157
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• 2000

Cytotoxic substances in dental calculus and root cementum of periodontally diseased teeth inhibit new attachment and regeneration. The purpose of scaling and root planing is to remove pathologic structures harboring these cytotoxic substances in order to create a biologically acceptable root surface. However, these procedures inevitably leave a non-biocompatible smear layer. Conventionally, the smear layer has been removed with low pH etching agents such as citric acid, phosphoric acid and tetracycline hydrochloride(TC). Lately, a supersaturated neutral pH etching solution of ethylene diamine tetraacetic acid(EDTA) has been found to be as effective as low pH etchants with respect to smear removal and to be superior in exposing root surfaceassociated collagen. The aim of the present study was to determine the effect of root surface treatment using EDTA on the initial attachment of human gingival fibroblasts. 27 human teeth, extracted due to severe periodontitis, were cut into dentin slices after root planing. The specimens were divided into TC group(treated with $50㎎/m{\ell}$ tetracycline-HCl, pH 1.52), EDTA group(treated with 17% EDTA, pH 7.4), and non-treated control group. After sterilization, 5th subcultured human gingival fibroblasts were seeded in each culture well containing a prepared root slice and incubated for 15 min., 60 min., and 4 hours in 5% $CO_2$ incubator at $37^{\circ}C$. At each incubation time, the number of attached fibroblasts were counted on the microphotographs taken at a magnification of x100. The difference of the number of attached cells between groups was statistically analyzed by the ANOVA followed by Duncan test in SPSS/PC＋programs. The results were as follows : 1. After incubation for 15 min, the attached cells were significantly more in EDTA group and TC group than non-treated control group(p<0.05), but there was no significance in the difference between EDTA group and TC group(p>0.1). 2. After incubation for 60 min and 4 hours, there was no significant difference in the number of attached cells between all groups(p>0.1). 3. In both EDTA group and TC group, there was no significant difference in the number of attached cells between different incubation(p>0.1). But in control group, the number of attached cells was significantly increased after incubation for 60 min, compared with incubation for 15 min(p<0.05). The above results suggest that root surface treatment using EDTA could enhance the initial attachment of gingival fibroblasts to root surface as effective as tetracycline-HCl.

• Journal of Periodontal and Implant Science
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• v.39 no.1
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• pp.59-70
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• 2009

Purpose: The purpose of this study was to investigate the degree of compliance with supportive periodontal therapy(SPT), to determine if any significant differences existed in the characteristics of compliant, erratically compliant and non-compliant patients and to identify reasons for poor compliance. Materials and methods: Four hundred five patients who initially visited between July 2003 and December 2004 and were treated until June 2005 were retrospectively evaluated for their compliance with SPT in terms of attendance for a recommended schedule of visits. Patients' compliance was classified as complete compliance(attended more than 80% of the recommended appointments), erratic compliance(attended less than 80% of the recommended appointments or discontinued) and non-compliance(did not return for SPT). Analysis was made for each group to correlate the degree of compliance with gender, age, smoking, distance between their houses and the hospital, disease severity, type of therapy, implant, plaque control instruction and systemic diseases. Tele research of erratically compliant and non-compliant patients was carried out to identify reasons for their poor compliance. Results: Only 24.7% of the patients were in complete compliance. The highest drop-out rate(32.4%) occurred in the first year. A significantly greater percentage of non-smokers and patients who finished plaque control instruction were in complete compliance. A significantly greater percentage of patients without implant and patients who had been treated by only scaling and root planing were in non-compliance. More males were found to be compliant with SPT, although this was marginally significant. There were no significant differences between compliant, erratically compliant and non-compliant patients with regard to age, distance, disease severity and systemic disease. The survey revealed that the main reasons for poor compliance with SPT were inconvenient location and insufficient time. Conclusion: Patients' compliance with SPT was poor and the highest drop-out rate(32.4%) occurred in the first year. Significant relationships were found between the degree of compliance and smoking, type of therapy, implant, plaque control instruction and gender.