• 대한치과보철학회지
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• 제35권2호
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• pp.401-412
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• 1997

There has been many researches aimed at reinforcing the strength of resin, and these have led to the development and use of numerous materials in recent years. A case in point, is the recent development of plasma-treated polyethylene fiber which has been used mainly in fixed provisional restoration to reduce the incidence of fractures. This study aims at assessing whether plasma-treated polyethylene fiber as applied to composite resin is effective in increasing the flexural strength and how applied portions affect this. Twenty-four applied and eight unapplied composite resin bars were fabricated. Twenty-four applied specimens were divided into three groups. Plasma treated polyethylene fiber was applied to the groups each with different portions of composite resin. In the first group, plasma-treated polyethylene fiber was not applied. In the second group, fiber was applied to the compression side of composite resin. Fiber was applied to the tension side in the third group, while fiber was embedded in the tension side of the composite resin in the fourth group. Each specimen was tested by use of a three-point bending strength test with an instron testing machine, and the flexural strength was calculated. The following results were obtained. : 1. Under the conditions of this study, the third and fourth groups demonstrated a statistically greater flexural strength compared to the first and second groups. 2. But there was no statistically significant difference, not only between the first group and the second group, but also between the third group and the fourth group. Taken together, it can be concluded that plasma-treated polyethylene fiber applied to composite resin is an effective method in increasing flexural strength, and the best way of increasing the flexural strength is by application of plasma-treated polyethylene fiber to the tension side, or the embedding of same in composite resin. It must be mentioned however that this test used a static single-load test method. This method determined the maximum stresses that could be tolerated, but this might not be valid where the prediction of clinical failure is concerned. In order therefore to clinically utilize plasma-treated polyethylene fiber to reinforce the composite resin, it is suggested that a further study which considers the various loads be undertaken.

• 한국염색가공학회지
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• 제27권1호
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• pp.18-26
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• 2015

para-aramid fibers were treated by atmosphere air plasma to improve the interfacial adhesion. The wettability of plasma-treated aramid fiber was observed by means of dynamic contact angle surface free energy measurement. Surface roughness were investigated with the help of scanning electron microscopy and atomic force microscopy. The tensile test of aramid fiber roving was carried out to determine the effect of plasma surface treatments on the mechanical properties of the fibers. A pull-out force test was carried out to observe the interfacial adhesion effect with matrix material. It was found that surface modification and a chemical component ratio of the aramid fibers improved wettability and adhesion characterization. After oxygen plasma, it was indicated that modified the surface roughness of aramid fiber increased mechanical interlocking between the fiber surface and vinylester resin. Consequently the oxygen plasma treatment is able to improve fiber-matrix adhesion through excited functional group and etching effect on fiber surface.

• Journal of Nutrition and Health
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• 제39권3호
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• pp.244-251
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• 2006

The purpose of this study was to observe the effects of cellulose and pectin on glucose and plasma lipid concentrations in healthy women. Eight female collage students were participated voluntarily. All subjects received a fiber-free control diet (CD), cellulose diet (CED), pectin diet (PTD) with each diet for a period of three days with a 4 day interval. The food intake of subjects were monitored every day and plasma level of glucose, triglyceride, total cholesterol were determined at last day. Blood glucose, plasma triglyceride, total cholesterol were measured at fasting state and 30, 60, 90, 120, and 180 minute after consuming each diet. Plasma glucose concentrations (AUC: Area Under the Curve) of pectin diet was $122.7{\pm}4.0mg/dl$ and that of cellulose diet was $147.6{\pm}8.4mg/d$, but they were significantly lower than in comparison with those of control diet ($197.1{\pm}11.6mg/dl$) (p<0.05) Plasma triglyceride concentrations of the CED ($-83.9{\pm}22.2mg/dl$) PTD ($-9.7{\pm}26.1mg/dl$) showed gradual decrease after each test diet feeding but not significantly different in each dietary fiber added diet (p<0.05). Plasma cholesterol concentrations of the CD was not significantly different in PTD, but PTD was significantly lower than the CED until 3 hours after consuming each test meal (p<0.05). In conclusion, in spite of total cholesterol was reduced only by pectin, glucose and triglyceride were lower than control diet in dietary fiber intake. But there were no significant differences each dietary fiber.

• Transactions on Electrical and Electronic Materials
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• 제14권3호
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• pp.133-138
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• 2013

Acrylonitrile-butadiene-styrene (ABS) plastic is a polymer material extensively used in electrical and electronic applications. Nickel (Ni) thin film was deposited on ABS by electroless plating, after its surface was treated and modified with atmospheric plasma generated by means of dielectric barrier discharges (DBDs) in air. The method in this study was developed as a pre-treatment for electroless plating using DBDs, and is a dry process featuring fewer processing steps and more environmentally friendliness than the chemical method. After ABS surfaces were modified, surface morphologies were observed using a scanning electron microscope (SEM) to check for any physical changes of the surfaces. Cross-sectional SEM images were taken to observe the binding characteristics between metallic films and ABS after metal plating. According to the SEM images, the depths of ABS by plasma are shallow compared to those modified by chemically treatment. The static contact angles were measured with deionized (DI) water droplets on the modified surfaces in order to observe for any changes in chemical activities and wettability. The surfaces modified by plasma showed smaller contact angles, and their modified states lasted longer than those modified by chemical etching. Adhesion strengths were measured using 3M tape (3M 810D standard) and by 90° peel-off tests. The peel-off test revealed the stronger adhesion of the Ni films on the plasma-modified surfaces than on the chemically modified surfaces. Thermal shock test was performed by changing the temperature drastically to see if any detachment of Ni film from ABS would occur due to the differences in thermal expansion coefficients between them. Only for the plasma-treated samples showed no separation of the Ni films from the ABS surfaces in tests. The adhesion strengths of metallic films on the ABS processed by the method developed in this study are better than those of the chemically processed films.

• Journal of Pharmaceutical Investigation
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• 제35권4호
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• pp.287-293
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• 2005

The purpose of the present study was to evaluate the bioequivalence of two glimepiride tablets, Amaryl tablet (Handok & Aventis Korea, reference drug) and Mepiril tablet (Myungmoon Pharm. Co., Ltd., Korea, test drug), according to the guidelines of Korea Food and Drug Administration (KFDA). After adding an internal standard (glibenclamide) to human plasma, plasma samples were extracted using 1mL of methyl tertiary butyl ether. Compounds extracted were analyzed by reverse-phase HPLC with multiple reaction monitoring (MRM) mode analyte detection. This method for determination glimepiride proved accurate and reproducible, with a limit of quantitation of 2 ng/mL in human plasma. Twenty-four healthy male Korean volunteers received each medicine at the glimepiride dose of 2 mg in a $2{\times}2$ crossover study. There was a one-week washout period between the doses. Plasma concentrations of glimepiride were monitored by a LC-MS/MS for over a period of 12 hr after the administration. $AUC_t$ (the area under the plasma concentration-time curve from time zero to 12 hr) was calculated by the linear trapezoidal rule method. $C_{max}$ (maximum plasma drug concentration) and $T_{max}$ (time to reach $C_{max}$) were compiled from the plasma concentration-time data. Analysis of variance was carried out using logarithmically transformed $AUC_t$ and $C_{max}$. No significant sequence effect was found for all of the bioavailability parameters indicating that the crossover design was properly performed. The 90% confidence intervals of the $AUC_t$ ratio and the $C_{max}$ ratio for Amaryl/Mepiril were log 0.9583-log 1.1357 and log 1.0570-log 1.2376, respectively. These values were within the acceptable bioequivalence intervals of log 0.80-log 1.25. Taken together, our study demonstrated the bioequivalence of Amaryl and Mepiril with respect to the rate and extent of absorption.

• 한국추진공학회지
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• 제19권1호
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• pp.25-32
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• 2015

원통 모델에 공기저항저감 효과를 검증하기 위해서 원통형에 적합한 유연성 플라즈마 구동기를 제작하였다. 다양한 풍속에서 플라즈마 유동제어 풍동시험을 수행하였으며, CFD 해석과 유동가시화를 수행하였다. 풍속이 느린 저속 구간에서는 유동박리가 발생하지 않아 플라즈마 유동제어 효과가 없었다. 풍속 14 m/s 에서 14% 정도 항력이 저감되었으며, 풍속이 증가된 17 m/s 의 경우 항력이 27% 저감되었다. CFD 해석과 유동가시화의 비교를 통해 DBD플라즈마 구동기는 원통 주변의 압력차를 감소시켜 와류의 크기가 줄어든 것으로 확인되었다.

• 한국분말재료학회지
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• 제18권3호
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• pp.226-237
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• 2011

W-ZrC and W-HfC composite powders were fabricated by the Plasma Alloying & Spheroidization (PAS) method and the powders were sprayed into hybrid coating layers by using Low Vacuum Plasma Spray (LVPS) process, respectively. Microstructure, mechanical properties, and ablation characteristics of the fabricated coating layers were investigated. The LVPS process led to successful production of W-Carbide hybrid coatings, approximately 400 ${\mu}M$ or above in thickness. As the substrate preheating temperature increased from $870^{\circ}C$ to $917^{\circ}C$, the hardness of the W-ZrC coating layer increased due to decreased porosity. Vickers hardness showed higher value (about 108.4 HV) in W-ZrC hybrid coating material compared to that of W-HfC while adhesive strength was found to be similar in both coating layers. The plasma torch test revealed good ablation resistance of the W-Carbide hybrid coating layers. The relatively high performance W-ZrC coating layer at the elevated temperature is thought to be attributed to both the strengthening effect of ZrC particle remained in the layer and the formation of ZrO2 phase with high temperature stability.

• 한국환경과학회지
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• 제29권5호
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• pp.575-578
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• 2020

The plasma cortisol of nurserypigs was examined using an outdoor efficacy testwith a digital content-based approach in animal welfare convergence types. Nine nurserypigs,without discriminating between female and male, were classified into 2 groups of 3 pigs each: control and group 1 (effect+nature), control and group 2(effect+nature+music). The control group was the same for group 1 and 2 to compare the effects using a t-test. There was no significant difference in plasma cortisol levels between the control group and group 1 until 4 h after stress induction. However, significant differences were subsequently found between the control group and group 1 from 8 h to 72 h (p<0.05). Further, plasma cortisol was not affected in group 2 at 0 h through 8 h and 72 h. At 12 h through 48 h, group 2 showed a reduction in plasma cortisol level compared to the control group(p<0.05). These results indicated that after stress induction, applying effect plus nature or effect plus nature plus music can effectively decrease plasma cortisol levels in nursery pigs within8 h through 72 h and may serve as a better model for digital content-based approach in animal welfare convergence types.

• The Journal of Advanced Prosthodontics
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• 제10권6호
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• pp.408-414
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• 2018

PURPOSE. This study aimed to assess the effect of non-thermal plasma on the shear bond strength of resin cements to polyetherketoneketone (PEKK) in comparison to other surface treatment methods. MATERIALS AND METHODS. Eighty PEKK discs were subjected to different surface treatments: (1) Untreated (UT); (2) Non-thermal plasma (NTP); (3) Sandblasting with $50{\mu}m$ $Al_2O_3$ particles (SB); and (4) Sandblasting + Non-thermal plasma (SB+NTP). After each surface treatment, the contact angle was measured. Surface conditioning with Visio.Link was applied in all groups after pre-treatment. RelyX Unicem resin cement was bonded onto the PEKK specimens. After fabrication of the specimens, half of each group (n=10) was initially tested, while the other half was subjected to thermocycling ($5^{\circ}C$ to $55^{\circ}C$ at 10,000 cycles). Shear bond strength (SBS) testing was performed using a universal testing machine, and failure modes were assessed using stereomicroscopy. The SBS results were analyzed statistically using one-way ANOVA followed by Tukey's post hoc test. Independent t-test was used to examine the effect of thermocycling (P<.05). RESULTS. The highest SBS values with or without thermocycling were observed with PEKK specimens that were treated with SB+NTP followed by the SB group. The lowest SBS results were observed in the UT groups. CONCLUSION. The shear bond strength between PEKK and resin cements was improved using non-thermal plasma treatment in combination with sandblasting.

• 한국진공학회:학술대회논문집
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• 한국진공학회 1999년도 제17회 학술발표회 논문개요집
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• pp.212-212
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• 1999

Ar-O2 분위기의 Plasma 표면 처리된 OPP 의 polymer 위에 약 400$\AA$ 정도로 sputter 코팅된 Al의 부착력에 관하여 연구를 하였다. 금속과 polymer와 같이 성질이 서로 다른 물질이 서로 결합할 때 접착력은 제품의 성능과 신뢰도를 결정하는데 매우 중요한 인자이다. 최근 고분자재료의 표면을 플라즈마 처리 (plasma surface treatment)에 의해 고분자와 금속도포(coating) 층간의 접착력향상에 따라, 증착필름 및 인쇄용 필름 등의 기능도 향상시킬 수 있다. 저온 plasma를 이용한 표면처리는 plastic 재료가 가지고 있는 기본적인 특성을 저해하지 않고, 그 표면 층만을 개량하는 plasma 또는 sputter etching 갚은 electrical discharge 방법은 진공 증착 방식에서 많이 사용되고 있다. 7$\mu\textrm{m}$의 두께 OPP polymer를 10m/min의 속도로 OPP의 표면을 연속 plasma pretreatment를 하였다. 5$\times$10-2torr에서, PEM(Plasma Emission Monitor)를 이용하여 plasma intensity에 따른 Ar/O2비를 변화시키면서 test를 하였다. AFM과 XPS를 이용하여 OPP의 표면분석을 하였다. 이 plasma처리는 기존의 D.C plasma 처리 방식과는 달리 Midium frequency AC voltage hollow cathod 방식으로 plasma를 발생된 high energy plasma 분위기를 만들 수 있다. 이러한 방식은 -cycle일 때 plasma로부터 발생된 전자가 polymer 표면을 bombard 하게 되고, +cycle 일 때 polymer 표면이 cathod 가 되어 active ion에 의해 sputtering 이 된다. 이때 plasma 처리기의 polymer 기판 후면에 magnet를 설치하여 높은 ionization을 발생시켜 처리 효과를 한층 높여 주었다. 이 plasma 처리는 표면 청정화, 표면 etching 이 동시에 행하는 것과 함께 장시간 처리에 의해 표면에서는 미세한 과, C=C기, -C-O-의 극성기의 도입에 의한 표면 개량이 된다는 것을 관찰할 수 있다. OPP polymer 표면을 Ar 100%로 plasma 처리한 경우 C-O, C=O 등의 carbonyl가 발생됨을 알 수 있었다. C-O, C=O 등의 carbynyl polor group이 도입됨에 따라 sputter된 Al의 접착력이 향상됨을 알 수 있으며, TEM 관찰 결과 grain size도 상당히 작아짐을 알 수 있었다.