• International Journal of Oral Biology
• /
• v.43 no.2
• /
• pp.83-91
• /
• 2018

Nonthermal atmospheric plasma has been studied for its many biomedical effects, such as tooth bleaching, wound healing, and coagulation. In this study, the effects of dentinal tubules occlusion were investigated using fluoride-carboxymethyl cellulose (F-CMC) gel, nano-sized hydroxyapatite (n-HA), and nonthermal atmospheric plasma. Human dentin specimens were divided to 5 groups (group C, HA, HAF, HAP, and HAFP). Group HA was treated with n-HA, group HAF was treated with n-HA after a F-CMC gel application, group HAP was treated with n-HA after a plasma treatment and group HAFP was treated with n-HA after a plasma and F-CMC gel treatment. The occlusion of dentinal tubules was investigated using scanning electron microscopy (SEM) and energy dispersive x-ray spectroscopy (EDS), which shows Ca/P ratio. In the EDS results, a higher Ca/P ratio was shown in the groups including n-HA than in the control group. The specimens of group HAP and HAFP had a higher Ca/P ratio in retentivity. In the SEM results, there was not a significant difference in the amount of times applied. Therefore, this study suggests F-CMC gel and n-HA treatment using nonthermal atmospheric plasma will be a new treatment method for decreasing hypersensitivity.

• Journal of Technologic Dentistry
• /
• v.39 no.1
• /
• pp.55-65
• /
• 2017

Purpose: The study has been undertaken on several factors that may influence on the orthodontic treatment satisfaction with the subject of male and female university students who have experience in receiving the orthodontic treatment by visiting orthodontic clinic. Methods: This study has implemented questionnaire survey for 350 male and female university students who have experience in receiving the orthodontic treatment by visiting orthodontic clinic due to the mall occlusion, From the 350 questionnaires collected, a total of 291 copies (83.1%) excluding the questionnaires that have inconclusive response or erroneous response is used as the research analysis data Results: The orthodontic treatment satisfaction is significantly higher for students in large cities and mid- to small sized cities than students in rural area, and it was higher for students with mid-economic class that students of upper class and lower class. It is shown for a student that began the orthodontic treatment from the elementary school, a student that had 5 times or more of brushing teeth for each day had significantly higher level of satisfaction that students that are not. In addition, a student that knows well of the oral hygiene management method, a student that had the fluoride application treatment during the orthodontic treatment period and a student that used the toothbrush for orthodontic service had significantly higher level of satisfaction that students that are not. Conclusion: Factors influencing on the orthodontic treatment satisfaction are very diverse and it is considered that it requires effort to improve the quality of medical service and sufficient understanding on several factors to improve the orthodontic treatment satisfaction for patients as well as the encouragement for orthodontic treatment patients of the relevant people in orthodontic clinics that provide the orthodontic clinic service.

• ETRI Journal
• /
• v.38 no.4
• /
• pp.675-684
• /
• 2016

This paper demonstrates the effect of fluoride-based plasma treatment on the performance of $Al_2O_3/AlGaN/GaN$ metal-insulator-semiconductor heterostructure field effect transistors (MISHFETs) with a T-shaped gate length of $0.20{\mu}m$. For the fabrication of the MISHFET, an $Al_2O_3$ layer as a gate dielectric was deposited using atomic layer deposition, which greatly decreases the gate leakage current, followed by the deposition of the silicon nitride layer. The silicon nitride layer on the gate foot region was then selectively removed through a reactive ion etching technique using $CF_4$ plasma. The etching process was continued for a longer period of time even after the complete removal of the silicon nitride layer to expose the $Al_2O_3$ gate dielectric layer to the plasma environment. The thickness of the $Al_2O_3$ gate dielectric layer was slowly reduced during the plasma exposure. Through this plasma treatment, the device exhibited a threshold voltage shift of 3.1 V in the positive direction, an increase of 50 mS/mm in trans conductance, a degraded off-state performance and a larger gate leakage current compared with that of the reference device without a plasma treatment.

• Journal of the Korean Ceramic Society
• /
• v.39 no.3
• /
• pp.315-320
• /
• 2002

Treatment effects of dilute hydrofluoric acid (6 wt% HF) on the surface properties of $Al(OH)_3$ were investigated at the molar ratio of F/Al(fluoride/aluminum)=0.15. Temperature and pH variations in the reaction system were recorded to analyze reaction mechanism between $Al(OH)_3$ and aqueous Hf. The reaction of HF to the surface of $Al(OH)_3$ accompanied with a quantity of heat evolution, resulting in increasing temperature of a reactionsystem. And also the reaction was proceeded as transitional state which metastable ${\alpha}-form\;AlF_3{\cdot}3H_2O$ was transferred to insoluble ${\beta}$-form. The resulting ${\beta}-form\;AlF_3{\cdot}3H_2O$ formed by a surface treatment was identified by FT-IR and X-ray diffractormetry. The formation of ${\beta}$-form aluminum fluoride hydrates with diameter less than $1{\mu}m$ on the surface of $Al(OH)_3$ could be visulaized by SEM imgae, making up a coating layer as precipitate-like. The surface whiteness of $Al(OH)_3$ treated with aqueous HF was furthermore increased approximately 6.6% due to the formation of surface hydrates.

• Membrane and Water Treatment
• /
• v.9 no.1
• /
• pp.53-62
• /
• 2018

In this study, vacuum membrane distillation (VMD) was used to treat high-salinity wastewater (concentration about 17%) discharged by chlor-alkali plant after resin regeneration. The feasibility of VMD for the treatment of real saline wastewater by using Polyvinylidene fluoride (PVDF) microporous plate membrane with a pore diameter of $0.2{\mu}m$ was investigated. The effects of critical operating parameters such as feed temperature, velocity, vacuum degree and concentration on the permeate water flux were analyzed. Numerical simulation was used to predict the flux and the obtained results were in good agreement with the experimental data. The results showed that an increase in the operating conditions could greatly promote the permeate water flux which in turn decreased with an increase in the concentration. When the concentration varied from 17 to 25%, the permeate water flux dropped marginally with time indicating that the concentration was not sensitive to the decrease in permeate water flux. The permeate water flux decreased sharply until zero due to the membrane fouling resistance as the concentration varied from 25 to 26%. However, the conductivity of the produced water was well maintained and the average value was measured to be $4.98{\mu}s/cm$. Furthermore, a salt rejection of more than 99.99% was achieved. Overall, the outcome of this investigation clearly indicates that VMD has the potential for treating high-salinity wastewater.

• Membrane and Water Treatment
• /
• v.8 no.3
• /
• pp.211-223
• /
• 2017

In this work, an attempt was made to compare the effects of UV irradiation on the intrinsic and separation properties of membranes made of two different polymeric materials, i.e., polyvinylidene fluoride (PVDF) and polyetherimide (PEI). The changes on membrane structural morphologies and chemical characteristics upon UV-A exposure (up to 60 h) were studied by FESEM and FTIR, respectively. It was found that cracks and fractures were detected on the PVDF-based membrane surface when the membrane was exposed directly to UV light for up to 60 h. Furthermore, the mechanical strength and thermal stability of irradiated PVDF-based membrane was reported to decrease with increasing UV exposure time. The PEI membrane surface meanwhile remained almost intact throughout the entire UV irradiation process. Filtration experiments showed that the permeate flux of UV-irradiated PVDF membrane was significantly increased from approximately 11 to $16L/m^2.h$ with increasing UV exposure time from zero to 60 h. Oil rejection meanwhile was decreased from 98 to 85%. For the PEI-based membrane, oil rejection of >97% was recorded and its overall structural integrity was marginally affected throughout the entire UV irradiation process. The findings of this work showed that the PEI-based membrane should be considered as the host for photocatalyts incorporation if the membrane was to be used for UV-assisted wastewater treatment process.

• Journal of the korean academy of Pediatric Dentistry
• /
• v.23 no.3
• /
• pp.659-666
• /
• 1996

The treatment of complete avulsed teeth due to traumatic injuries is replantation procedure. The major complication of replantation are pulp necrosis, ankylosis, and root resorption. It is important to maintain the vitality of periodontal ligament to minimize the complications. The purpose of this case report is to consider the facts that affect the success rate and the prognosis of complete avulsed teeth after replantation. All of these cases had different conditions and transport media. The following results were observed: 1. The successive treatment of complete ayulsed teeth requires the maintainance of vitality of periodontal ligament. 2. The complication of replantation are inflammatory root resorption and ankylosis and in such case, proper endodontic treatment using calcium hydroxide medications and periodic observations are needed. 3. In case of delayed replantation, the use of fluoride and root planning procedure can help to achieve better result. 4. It is more esthetic and functional to maintain the avulsed tooth in mouth.

• Restorative Dentistry and Endodontics
• /
• v.26 no.1
• /
• pp.1-8
• /
• 2001

Dental Caries which has high prevalence rate, accounts for majority of dental diseases. Many treatment and preventive treatment has been developed, thereby reducing the prevalence rate, but in our country, fluoridization has not spread widely yet, so prevention has not been done satisfactorily. When dental caries progresses, irreversible damage of tooth structure occurs. In initial dental caries, demineralizing tooth structure can be remineralized, so restorative treatment is unnecessary. In this study, 20 teeth restored with composite resin without fluoride release were used and divided into two groups. Incipient dental caries were artificially made and demineralization procedure was done for 1 and 2 weeks, for each group. Changes in mineral contents around the margins were analysed with confocal laser scanning microscope. The results were as follow. 1. Both total fluorescence of the lesion and average fluorescence of the lesion of remineralized samples decreased compared to demineralizing state. (p＜0.01) 2. Confocal laser scanning microscopy can be used in quantitative analysis of mineral change. In result, confocal laser scanning microscopy can be used in quantitative analysis of mineral change and it could be used in many different fields of dentistry in the future.

• Journal of the Korean Society for Heat Treatment
• /
• v.25 no.2
• /
• pp.65-73
• /
• 2012

The Gas Diffusion Layer (GDL) of fuel cell, are required to provide both delivery of reactant gases to the catalyst layer and removal of water in either vapor or liquid form in typical PEMFCs. In this study, the fabrication of GDL containing Micro Porous Layer (MPL) made of the slurry of PVDF mixed with carbon black is investigated in detail. Physical properties of GDL containing MPL, such as electrical resistance, gas permeability and microstructure were examined, and the performance of the cell using developed GDL with MPL was evaluated. The results show that MPL with PVDF binder demonstrated uniformly distributed microstructure without large cracks and pores, which resulted in better electrical conductivity. The fuel cell performance test demonstrates that the developed GDL with MPL has a great potential due to enhanced mass transport property due to its porous structure and small pore size.

• Journal of Korean Clinical Health Science
• /
• v.6 no.2
• /
• pp.1115-1125
• /
• 2018

purpose : The purpose of the study is to investigate opinion on the legalization of the actual work of clinical dental hygienists. Methods : A self-reported questionnaire was completed by 171 dental hygienists in Busan and Gyeongnam from December 1, 2017 to January 31, 2018. Structured questionnaires were uesd for analysis. The collected data was analyzed using IBM SPSS. Statistic 20.0. Results : The first, assist of dental treatment, Second, dental health care education and consulting duties, and third priority preventive duties were found to be the most important duties in the dental office. Currently, it was investigated perform in a lot of workplace. Preventive treatment tasks include scaling, teeth polishing, applying fluoride and assist of dental treatment include preparation for medical care, preparation for implant surgery, preparation for oral surgery, implant surgery assistant and patient care training, and preparation for periodontal surgery. Conclusion : As a result, the dental hygienist performing a lot of dental assist tasks, oral health education counseling and preventive duties. Nonetheless, clinical dental hygienists are outlaws due to the disparity between practical and legal duties. Therefore, it is urgent to legislate actual duties of dental hygienist so that experts can fully exercise the competency of the public in promoting dental health. Relevant governments and related organizations should take reasonable measures to solve this problem.