• Journal of Korean society of Dental Hygiene
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• v.15 no.5
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• pp.813-821
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• 2015

Objectives: The purpose of the study was to investigate the relationship between health behavior and oral symptoms in Korean adolescents. Methods: The subjects were 72,060 adolescents who were selected from the web-based survey of the 10th (2014) Korean Youth Risk Behavior of Korean Center for Disease Control. Data were analyzed by PASW statistics 18.0. A web-based self-reported questionnaire was completed by 74,167 middle and high school students. The subjects consisted of 36,470 boy students (52.2%) and 35,590 girl students (47.8%) from 400 middle schools and 400 high schools. Results: Multiple logistic regression analysis revealed that experience of oral symptoms were related with sex, age, academic achievement, economic status, alcohol drinking, moderate physical activity, muscular strength exercises, walking, fruit consumption, milk consumption, fast food consumption, snack consumption, daily tooth brushing frequency, use of fluoride toothpaste, school based oral health education, dental sealant and dental scaling. Conclusions: There were close relationship between heath behavior, oral health behavior, and experience of oral symptoms. To improve the health promotion for the adolescents, oral health program development and primary prevention strategy must be established.

• Bulletin of the Korean Chemical Society
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• v.26 no.11
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• pp.1891-1894
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• 2005

• Proceedings of the Korean Fiber Society Conference
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• 1998.04a
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• pp.54-57
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• 1998

Recently, Manley's group published several papers on the blend of PVDF and poly(1, 4-butylene adipate) (PBA) chosen as a model system of somicrystallineisemicrystalline polymer blend.[1-4]. This blend system has several advantages over the other PVDF/semicrystalline polymer blends.(omitted)

• Biomolecules & Therapeutics
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• v.8 no.2
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• pp.179-183
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• 2000

To determine biosafety of fluorosilicic acid as a source of fluoride, we carried out acute toxicity and general pharmacological studies using mouse. Fluorosilicic acid had little effects on general behavior, pain response, convulsion, skeletal muscle function and intestinal mobility as compared to controls. It had either little adverse effects on alkaline phosphatase and collagen levels in osteoblast cells. This study supports the safety of fluorosilicic acid in animals.

• Proceedings of the Korean Fiber Society Conference
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• 2003.04a
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• pp.319-320
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• 2003

압전성과 초전성을 나타내는 고분자인 poly(vinylidene fluoride)(PVDF)는 poly(methyl methacrylate), poly(vinyl acetate), 및 Poly(vinyl methyl ketone)(PVMK) 등과 블렌딩하면 혼화성(miscibility)이 있다. 이들 블렌드물들을 용융온도 이상으로 승온시키면 낮은 온도에서는 균일상으로 존재하지만, 온도가 계속 증가하면 상분리되어 LCST(lower critical solution temperature)를 나타낸다[1]. 이러한 승온에 의한 상분리 거동에서 외부전장을 가하면 전기활성 고분자인 PVDF에 영향을 주어 상분리 거동이 변화될 것으로 예산된다. (중략)

• Proceedings of the Korean Fiber Society Conference
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• 2003.10b
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• pp.193-194
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• 2003

전기활성 고분자인 poly(vinylidene fluoride)(PVDF)를 전기 비활성 고분자와 블렌드시키는 경우 어떤 블렌드계에서는 용융 온도 이상에서 LCST(lower critical solution temperature) 상분리 거동을 나타내는데[1,2], 이때 외부 전장을 가해주면 이들의 상분리 거동에 영향을 미칠 수 있다[3]. PVDF와 블렌딩시켰을 때 LCST 상분리 거동을 나타내는 고분자로는 poly(methyl methacrylate), poly(ethyl methacrylate), poly(1,4-butylene adipate) (PBA) 등이 있다[l,3]. (중략)

• Journal of Korean society of Dental Hygiene
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• v.16 no.1
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• pp.147-153
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• 2016

Objectives: The purpose of the study is to investigate the relationship between fluorine concentration within finger nails and the level of dentifrice in dental hygiene students and non-health majoring students. Methods: A self-reported questionnaire was completed by seventy female college students living in Daegu and Gyeongbuk that are not supplied with fluoridation from May to June, 2014. Informed consent was approved by institutional review board (IRB). The questionnaire consisted of general characteristics of the subjects (11 items) and oral health behavior including number of toothbrushing, duration of toothbrushing, number of mouth rinsing, and amount of dentifrice. A dentist and a dental hygienist examined directly the subjects by the guideline of World Health Organization (WHO). The oral examination included decayed tooth, healthy tooth, and filled tooth. The nail samples were obtained from seventy female students. Results: Comparing the dental hygiene students and non-health majoring students, 62.5% of dental hygiene students used approximately 1300mg of dentifrice and 55.2% of non-health majoring students used 1800mg or more of dentifrice. The non-health majoring students used more dentifrice (p<0.01). The fluorine concentration within nails was $1.9905{\mu}l/g$ in dental hygiene students and $3.2149{\mu}l/g$ in non-health majoring students. The fluorine concentration within nails in the dental hygiene students was significantly lower(p<0.01). Conclusions: The accumulation of fluoride in human body is not fully caused by dentifrice. However, The accumulation may occur due to toothbrushing so that it is necessary to educate the students about the right use of the dentifrice.

• Journal of Korean society of Dental Hygiene
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• v.9 no.4
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• pp.864-873
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• 2009

Objectives : This study was to collect data about oral health to develop preschool children' oral health program. Methods : This research was from July 20th to August 20th, 2008 with self-administrated questionnaires by post and e-mail. The response rate was 57.6%(144 of 250). Results : 1. Daycare center provided fruit(64.6%), bread(56.9%), milk(82.6%), yoghurt(47.9%). daycare center tend to provide cariogenic snacks and drinks such as bread, yoghurt. 2. 73.6% of teachers said they reward children with sweets for good behavior. 3. Activities related to oral health was done in daycare center were : children brush their teeth with fluoride toothpaste(79.9%), catering staff receive the education about nutrition(79.2%), children participate in the activities and training related to food(78.5%), using sugary food at a birthday party(77.3%), annual dental health check-up by a dentist(65.3%). 4. The percentages of guiding principles based on documentation in the topic of the oral health were : coping with a situation where a child injured his or her teeth(76.4%), annual dental health checkup by a dentist(72.2%), teachers supervise children's tooth brushing using a fluoride toothpaste(70.8%). 5. Documented guide or course for oral health includes the following; training for coping with tooth damage(76.4%), annual dental health check-up(72.2%), and coaching children to brush their teeth with toothpaste that contains fluoride(70.8%). Conclusions : It is believed that for better children's oral healthcare, childcare teacher should be given a range of in-depth oral health program. Furthermore, through detailed analysis on the documented guide of oral health, cooperation from the associated organization will be required to have the guide placed at the childcare center.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.11 no.3
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• pp.221-228
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• 1998

In this study, the $\beta$-Polyvinylidene fluoride(PVDF) thin films were fabricated by physical vapor deposition method. Also, the properties of dielectric relaxation were studied to understand carrier's behavior of PVDF thin films, to be regarded as the excellent piezo and pyroelectricity. In the process of vapor deposition, the $\beta$-PVDF thin films have been fabricated under the condition of the substrate temperature at 3$0^{\circ}C$, the applied electric field at 142.8kV/cm and the pressure at 2.0${\times}10^{-5}$torr. The dielectric properties of PVDF have been studied in the frequency range 10Hz to 1MHz at temperature from 30 to $100^{\circ}C$. The relative dielectric constant of $\alpha$ and $\beta$-PVDF were 6.8 and 9.8, respectively, under a frequency of 1kHz. Such a phenomenon was caused by the decrease in intermolecular forces originated by the phase-transition from the TGTG' molecular conformation to the TT planar zig-zag conformation. And the relative dielectric constant is increased as a measuring temperature increases, because of the reduction of relaxation time caused by the decrease of intermolecular force.

• Membrane Journal
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• v.33 no.2
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• pp.53-60
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• 2023

Mechanical energy can be harvested by triboelectric nanogenerators (TENG) from biological and environmental systems. In wearable electronics, TENG has a lot of significance as biomechanical energy can be harvested from the motion of humans, which is applied in vibrational sensors. Wearable TENG is prone to moisture and polytetrafluoroethylene (PTFE) is an excellent hydrophobic material used in these applications. The presence of highly electronegative fluorine atoms leads to very low surface energy. At the same time, the performance of the device increases due to the efficient capture of the electrons on the microporous membrane surface. This similar behavior occurs with polyvinylidene fluoride (PVDF) due to the presence of fluoride atoms, which is relatively less as compared to PTFE.