• 대한치과의사협회지
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• 제12권10호
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• pp.767-770
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• 1974

A 12 years old patient having rampant dental caries on permanent dentition has been treated under operative procedures. In addition to this operative treatment the nutritional survey and the caries activity was checked, and performed the oral hygiene instruction to the patient. As the consequences of above procedures the following results were obtained: 1. The familial history and eating habits checkings were helpful for better dental health guide and caries control. 2. The restriction of mono & disaccharide intake and topical application of 8% stannous fluoride at least two times revealed excellent control effect for recurrent dental caries.

• 대한소아치과학회지
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• 제32권3호
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• pp.427-436
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• 2005

복합레진 표면에 대한 APF gel 도포는 표면을 거칠게 하고 세균 부착을 증가시킨다. 본 연구는 Filtek Z250(FZ), Filtek Supreme Universal(FS)과, 실험적으로 나노충전재를 각각 0%, 3%, 6% 포함시켜 만든 복합레진(E0, E3, E6)으로 제작한 레진 시편을, APF gel을 적용한 군과 적용하지 않은 군으로 나누어 Streptococcus mutans의 부착량과 표면 조도를 측정하고 비교, 평가하여 다음과 같은 결과를 얻었다. 1. APF gel을 적용하지 않은 레진 시편에 대한 S. mutans 부착량은 FS에서 가장 적었고, FZ, E3, E6에 대한 부착량보다는 유의하게 낮았다(p<0.05). 2. 모든 레진군에서 APF gel을 적용한 레진 시편에 대한 S. mutans 부착량은 APF gel을 적용하지 않은 시편에 대한 부착량보다 유의하게 높았다(p<0.05). 3. APF gel을 적용한 레진 시편에 대한 S. mutans 부착량은 레진군간 유의한 차이를 보였으며(p<0.05), FS, FZ, E0, E3, E6의 순서로 높은 값을 보였다. 4. APF gel 적용 전이나 후에, 레진군간 표면조도의 차이는 유의하지 않았다(p>0.05).

• 대한심미치과학회지
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• 제8권1호
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• pp.64-74
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• 1999

The use of fluoride and other preventive methods caused a dramatic decline in dental caries and the need for restorative dentistry. In our modern society that places a high value on appearance, emphasis is now shifting towards esthetic dentistry which has experienced a high popularity with the development of bonding techniques and materials including porcelain and composite. To satisfy patients wanting whiter teeth and a better looking smile, there are many treatment options ranging from full crown coverage to conservative procedures such as bleaching. Whether bleaching should be combined with other esthetic procedures or used alone depends on the type of discoloration and the patient's willingness to accept the various treatment options. Therefore, in order to obtain a successful esthetic outcome, careful diagnosis and treatment planning followed by consultation with the patient is of utmost importance.

• 한국결정성장학회:학술대회논문집
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• 한국결정성장학회 1998년도 PROCEEDINGS OF THE 14TH KACG TECHNICAL MEETING AND THE 5TH KOREA-JAPAN EMGS (ELECTRONIC MATERIALS GROWTH SYMPOSIUM)
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• pp.145-148
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• 1998

Fluoride({{{{ { CaF}_{2 } }}}}) films exhibited a cubic structure with similar lattice constant to that of Si and have sufficient breakdown electric field as gate dielectric material. Therefore, {{{{ { CaF}_{2 } }}}} are expected to replace conventional insulator such {{{{ { SiO}_{ 2},{Ta}_{2}{O}_{ 2} and{Al}_{2}{O}_{5}. However, {CaF}_{2}}}}} films showed hystereisis properties due to mobile charges in the film. To solve this problem we performed thermal treatment and achieves field. C-v results indicate a reduced hystereisis window of {{{{ }}}}ΔV =0.2v, LOW INTERFACE STATE {{{{{D}_{it}=2.0 TIMES {10}^{11}{cm}^{-1}{eV}^{-1}}}}} in midgap, and good WIS diode properties. We observed a preferential crystallization of(200) plane from XRD analysis. RTA treatment effects on various material properties of {{{{{CaF}_{2}}}}} are presented in this paper.

• 한국결정성장학회지
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• 제28권1호
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• pp.1-8
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• 2018

The 23 wt% polyvinylidene fluoride (PVDF)/15 wt% polyurethane (PU) fibers were electrospun using the conjugated nozzle at a flow rate of 1.0 mL/h and an electric field of 1 kV/cm. The formation of ${\beta}$ crystal phase in the PVDF and the PVDF/PU fibers was confirmed by Fourier transform infrared spectroscopy. After electrospinning, the asspun fibers were immersed in a boiling water and then dried at $100^{\circ}C$ in a convection oven to make a crimp phenomenon. The crimps with a diameter of $2.0{\pm}0.08{\mu}m$ were observed for the PVDF/PU fibers after hydrothermal treatment without sacrificing the extent of ${\beta}$ crystal phase. All the PU, PVDF and PVDF/PU fibers exhibited average cell viability of more than 98 %. The cell proliferation results suggested that L-929 cells adhered well to the PU, PVDF and PVDF/PU fibers and proliferated continuously with increasing time, indicating that the PVDF/PU fibers are highly applicable to the biomedical applications.

• Membrane and Water Treatment
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• 제7권5호
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• pp.377-401
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• 2016

To study the effect of titanium dioxide ($TiO_2$) nanoparticles on membrane performance and structure and to explore possible improvement of using mixed solvents in the casting solution, composite polyvinylidene fluoride (PVDF) ultrafiltration membranes were prepared via immersion precipitation method using a mixture of two solvents triethyl phosphate (TEP) and dimethylacetamide (DMAc) and addition of $TiO_2$ nanoparticles. Properties of the neat and composite membranes were characterized using scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDS), Atomic force microscopy (AFM) and contact angle and membrane porosity measurements. The neat and composite membranes were further investigated in terms of BSA rejection and flux decline in cross flow filtration experiments. Following hydrophilicity improvement of the PVDF membrane by addition of 0.25 wt.% $TiO_2$, (from $70.53^{\circ}$ to $60.5^{\circ}$) degree of flux decline due to irreversible fouling resistance of the composite membrane reduced significantly and the flux recovery ratio (FRR) of 96.85% was obtained. The results showed that using mixed solvents (DMAc/TEP) with lower content of $TiO_2$ nanoparticles (0.25 wt.%) affected the sedimentation rate of nanoparticles and consequently the distribution of nanoparticles in the casting solution and membrane formation which influenced the properties of the ultimate composite membranes.

• 대한임상독성학회지
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• 제8권1호
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• pp.43-45
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• 2010

A 22-year-old woman was referred to our emergency department for the treatment of a chemical injury on her arm. She had accidentally spilled 99% trifluoroacetic anhydride (TFAA) over her left forearm during an organic chemistry experiment. She visited a primary care unit, and then she was referred to our hospital for inactivation of the released fluoride ions. Her skin lesions were different from those caused by hydrofluoric acid (HF) injury. The injured area showed painful whitish maculae and patchy areas with accentuated rim. No vesiculation and bulla formation was detected. We intradermally injected a 5% solution of calcium through a 24-gauge needle into the burned skin. After the injection, she complained of more severe pain. Although TFAA contains fluorine, it does not release free fluoride ions on contact with the skin, unlike HF. In fact, application of calcium gluconate for TFAA burns is not recommended. Rather, it should be avoided since it increases pain and local abscess formation.

• 환경위생공학
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• 제21권2호
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• pp.36-46
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• 2006

The purpose if this study was to investigate mother' oral health management behavior to their children. Two hundreds sixty seven mothers with elementary school students were surveyed among the residents living of Iksan city, Korea. A questionnaire was constructed and administered to the samples. The research focused in the following items: the subjects' socio-demographic factors such as education level and employment and so on; their knowledge of plaque; the leading causes of caries, regular dental examinations; dental treatment; their interest in their children's dental health; the frequency of the subjects examining their children's teeth; non-cariogenic food preparation, etc. Being based in collected data, mothers' oral health management behavior to their children were analyzed according to maternal socio-demographic factor and result were following. There was a difference in the subjects knowledge of dental plaque in accordance with their employment or unemployment and family income. There was no difference in mother's oral health management behavior to their children according to parents' education level, the subjects' age and family income. Most of mother answered the main reason of dental caries was that their children did not toothbrush their teeth regularly and there was a difference in the understanding of the subjects in accordance with the education level of fathers and family income. The subjects had a low understanding of the effect of preventing caries with the help of fluoride. They didn't have enough understanding of water fluoridation. So it is necessary that active campaigns should be launched to enlighten people in relation to the ways of preventing dental caries with fluoride.

• Membrane and Water Treatment
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• 제11권5호
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• pp.333-344
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• 2020

Advances in industrial development and waste management over several decades have reduced many of the impacts that previously affected ecosystems, however, there are still processes which discharge hazardous materials into environments. Among industries that produce industrial wastewaters, textile manufacturing processes play a noticeable role. This study was conducted to test a novel continuous combined commercial membrane treatment using polyvinylidene fluoride (PVDF), ultrafiltration (UF), and polyamide (PA) nanofiltration (NF) membranes for textile wastewater treatment. The synthetic textile wastewater used in this study contained sodium silicate, wax, and five various reactive dyes. The results indicate that the removal efficiency for physical particles (wax and resin) was 95% through the UF membrane under optimum conditions. Applying UF and NF hybrid treatment resulted in total effective removal of dye from all synthetic samples. The efficiency of sodium silicate removal was measured to be between 2.5 to 4.5% and 13 to 16% for UF and NF, respectively. The chemical oxygen demand in all samples was reduced by more than 85% after treatment by NF.

• 한국환경과학회지
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• 제19권11호
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• pp.1315-1322
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• 2010

A membrane bioreactor (MBR) was designed using polyvinylidene fluoride(PVDF)-type hollow fiber membrane modules with a treatment capacity of 10 ton/day. A pilot plant was installed in a sewage treatment plant and was operated with an intermittent aeration method which avoids any concentration gradient of suspended solids (SS) in the MBR. For continuous operation, the pilot plant was first tested with influent (mixed liquor suspended solid:MLSS of 1000-2000 mg/L) of aeration tanks in the sewage treatment plant. The MBR was pre-treated with washing water, 10% ethanol solution, 5% NaOCl solution and finally washing water, one after another. To demonstrate the effect of the MBR on sewage treatment, compared with conventional activated sludge processes, we investigated the relationships among permeate amount (LMH), change in operation conditions, influent MLSS level and sludge production. It was found that the optimum aeration rate and suction pressure were $0.3\;m^3$/min and 30~31 cmHg, respectively. Under stable conditions in aeration, suction pressure, influent flow rate and drainage, the SS removal efficiency was more than 99.99% even when the MLSS loading rate changes. Compared with conventional activated sludge processes, the MBR was more effective in cost reduction by 27% based on permeate amount and by 51.5% on sludge production.