• Proceedings of the Korean Vacuum Society Conference
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• 1999.07a
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• pp.161-161
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• 1999

In the field of material science, the interests and efforts to modify the surface of materials in agreement with the need of usage have been extensively increasing. he modification to improve the wettability of surface is very important is terms of adhesion, printing, etc. It is very difficult to modify metal surface into hydrophilic one. therefore, surfactant coating has been generally used in many cases. However, surfactant has disadvantages such as environmental problem, soluble in water. in this study, hydrophilic polymer films as alternative of surfactant were deposited on metal substrate by DC plasma polymerization. Hydrophilic polymer films deposited by DC plasma show many merits such as good wettability, stone adhesion to substrate, high resistance to most chemicals. Monomer gas and reactive gas were used as source plasma polymerization. Plasma polymerized films were fabricated with process parameters of deposition time, ratio of gas mixture, current, pressure, etc. Effects of these variables on wettability of plasma polymer films will be discussed. With XPS and FT-IR analyses of plasma polymeric films, the relation between wettability and chemical state of polymer films by DC plasma was investigated.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.23 no.6
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• pp.309-313
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• 2013

Silicon carbide (SiC) has recently drawn an enormous industrial interest because of its useful mechanical properties such as thermal resistance, abrasion resistance and thermal conductivity at high temperature. Especially, high purity SiC is applicable to the fields of power semiconductor and lighting emitting diode (LED). In this work, high purity carbon powders as raw material for high purity SiC were prepared by a RF induction thermal plasma. Dodecane ($C_{12}H_{26}$) as hydrocarbon liquid precursor has been utilized for synthesis of high purity carbon powders. It is found that the filtercollected carbon powders showed smaller particle size (10~20 nm) and low crystallinity compared to the reactor-collected carbon powders. The purities of reactor-collected and filter-collected carbon powders were 99.9997 % (5N7) and 99.9993 % (5N3), respectively. In addition, the impurities of carbon powders synthesized by RF induction thermal plasma were mainly originated from the surrounding environment.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• v.21 no.1
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• pp.59-67
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• 2018

Purpose: to compare cut off points corrected for age and gender (COOP) with fixed cut off points (FCOP) for fasting plasma insulin and Homeostatic model assessment-insulin resistance (HOMA-IR) for the diagnosis of IR in obese children and adolescents and their correlation with dyslipidemia. Methods: A multicenter, cross-sectional study including 383 subjects aged 7 to 18 years, evaluating fasting blood glucose, plasma insulin, and lipid profile. Subjects with high insulin levels and/or HOMA-IR were considered as having IR, based on two defining criteria: FCOP or CCOP. The frequency of metabolic abnormalities, the presence of IR, and the presence of dyslipidemia in relation to FCOP or CCOP were analyzed using Fisher and Mann-Whitney exact tests. Results: Using HOMA-IR, IR was diagnosed in 155 (40.5%) and 215 (56.1%) patients and, using fasting insulin, 150 (39.2%) and 221 (57.7%), respectively applying FCOP and CCOP. The use of CCOP resulted in lower insulin and HOMA-IR values than FCOP. Dyslipidemia was not related to FCOP or CCOP. Blood glucose remained within normal limits in all patients with IR. There was no difference in the frequency of IR identified by plasma insulin or HOMA-IR, both for FCOP and CCOP. Conclusion: The CCOP of plasma insulin or of HOMA-IR detected more cases of IR as compared to the FCOP, but were not associated with the frequency of dyslipidemia. As blood glucose has almost no fluctuation in this age group, even in the presence of IR, fasting plasma insulin detected the same cases of IR that would be detected by HOMA-IR.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.312-312
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• 2013

GaN based light emitting diodes (LEDs) are important devices that are being used extensively in our daily life. For example, these devices are used in traffic light lamps, outdoor full-color displays and backlight of liquid crystal display panels. To realize high-brightness GaN based LEDs for solid-state lighting applications, the development of p-type ohmic electrodes that have low contact resistivity, high optical transmittance and high refractive index is essential. To this effect, indiumtin oxide (ITO) have been investigated for LEDs. Among the transparent electrodes for LEDs, ITO has been one of the promising electrodes on p-GaN layers owing to its excellent properties in optical, electrical conductivity, substrate adhesion, hardness, and chemical inertness. Sputtering and e-beam evaporation techniques are the most commonly used deposition methods. Commonly, ITO films on p-GaN by sputtering have better transmittance and resistivity than ITO films on p-GaN by e-bam evaporation. However, ITO films on p-GaN by sputtering have higher specific contact resistance, it has been demonstrated that this is due to possible plasma damage on the p-GaN in the sputtering process. In this paper, we have investigated the advanced sputtering using plasma damage-free p-electrode. Prepared the ITO films on the GaN based LEDs by e-beam evaporation, normal sputtering and advanced sputtering. The ITO films on GaN based LEDs by sputtering showed better transmittance and sheets resistance than ITO films on the GaN based LEDs by e-beam evaporation. Finally, fabricated of GaN based LEDs by using advanced sputtering. And compared the electrical properties (measurement by using C-TLM) and structural properties (HR-TEM and FE-SEM) of ITO films on GaN based LEDs produced by e-beam evaporation, normal sputtering and advanced sputtering. As a result, It is expected to form plasma damage free-electrode, and better light output power and break down voltage than LEDs by e-beam evaporation and normal sputter.

• Journal of the Korean Society for Heat Treatment
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• v.17 no.2
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• pp.94-100
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• 2004

In order to improve the wear resistance of Ti-6Al-4V alloy, plasma carburization treatment was newly carried out without consumption of its good specific strength and fatigue life over the temperature. Effect of the plasma carburization was analyzed and compared with the non-treated alloy by microstructural observation, structure characterization and mechanical test. The plasma treated alloy formed a carburized layer of about $150{\mu}m$ in depth from the surface, where a fine and hard particles of TiC and $V_4C_3$ were homogeneously dispersed through the layer. The steady-static creep behaviors of Ti-6Al-4V alloy, using the constant stress creep tester, were investigated over the temperature range of $510{\sim}550^{\circ}C$(0.42~0.44Tm) and the stress range of 200~275 MPa. Stress exponent(n) was decreased from 9.32 of non-treatment specimen to 8.95 of carburized, however, the activation energy(Q) increased from 238 to 250 kJ/mol with the same condition as indicated above. From the above results, it can be concluded that the static creep deformation for Ti-6Al-4V alloy was controlled by the dislocation climb over the ranges of the experimental conditions.

• The Korean Journal of Physiology and Pharmacology
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• v.20 no.6
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• pp.581-593
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• 2016

The advantages of monounsaturated fatty acids (MUFAs) on insulin resistance and type 2 diabetes mellitus (T2DM) have been well established. However, the molecular mechanisms of the anti-diabetic action of MUFAs remain unclear. This study examined the anti-hyperglycemic effect and explored the molecular mechanisms involved in the actions of fish oil- rich in MUFAs that had been acquired from hybrid catfish (Pangasius larnaudii${\times}$Pangasianodon hypophthalmus) among experimental type 2 diabetic rats. Diabetic rats that were fed with fish oil (500 and 1,000 mg/kg BW) for 12 weeks significantly reduced the fasting plasma glucose levels without increasing the plasma insulin levels. The diminishing levels of plasma lipids and the muscle triglyceride accumulation as well as the plasma leptin levels were identified in T2DM rats, which had been administrated with fish oil. Notably, the plasma adiponectin levels increased among these rats. The fish oil supplementation also improved glucose tolerance, insulin sensitivity and pancreatic histological changes. Moreover, the supplementation of fish oil improved insulin signaling ($p-Akt^{Ser473}$ and p-PKC-${\zeta}/{\lambda}^{Thr410/403}$), $p-AMPK^{Thr172}$ and membrane GLUT4 protein expressions, whereas the protein expressions of pro-inflammatory cytokines (TNF-${\alpha}$ and nuclear NF-${\kappa}B$) as well as p-PKC-${\theta}^{Thr538}$ were down regulated in the skeletal muscle. These data indicate that the effects of fish oil-rich in MUFAs in these T2DM rats were partly due to the attenuation of insulin resistance and an improvement in the adipokine imbalance. The mechanisms of the anti-hyperglycemic effect are involved in the improvement of insulin signaling, AMPK activation, GLUT4 translocation and suppression of pro-inflammatory cytokine protein expressions.

• Journal of the Microelectronics and Packaging Society
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• v.21 no.3
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• pp.25-29
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• 2014

Plasma organic thin film for PCB surface finish is a potential replacement of the conventional PCB finishes because of environment-friendly process, high corrosion-resistance and long shelf life over 1 year. In this study, solder joint properties of the plasma organic surface finish were estimated and compared with OSP surface finish. The plasma surface finish was deposited by chemical vapor deposition from fluorine-based precursors. The thickness of the plasma organic coating was 20 nm. Sn-3.0Ag-0.5Cu (SAC305) solder was used as solder joint materials. From a salt spray test, the plasma organic coating had higher corrosion resistance than the OSP surface finish. The spreadability of SAC305 on plasma organic coating was higher than that on OSP surface finish. SEM and TEM micrographs showed that the interfacial microstructure of the plasma surface finish sample were similar to that of the OSP sample. Solder joint strength of the plasma finish sample was also similar to that of the OSP finished sample.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.33 no.4
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• pp.153-157
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• 2023

In order to manufacture a semiconductor circuit, etching, cleaning, and deposition processes are repeated. During these processes, the inside of the processing chamber is exposed to corrosive plasma. Therefore, the coating of the inner wall of the semiconductor equipment with a plasma-resistant material has been attempted to minimize the etching of the coating and particle contaminant generation. In this study, we mixed AlF₃ powder with the solid-state reacted yttrium oxyfluoride (YOF) in order to increase plasma-etching resistance of the plasma spray coated YOF layer. Effects of the mixing ratio of AlF₃ with YOF powder on crystal structure, microstructure and chemical composition were investigated using XRD and FE-SEM. The plasma-etching ratios of the plasma-spray coated layers were calculated and correlation with AlF₃ mixing ratio was analyzed.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.12
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• pp.2276-2280
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• 2011

An indium-tin-oxide (ITO) is normally used as a substrate in organic photovoltaic cells. We examined the effects of an oxygen ($O_2$) plasma treatment on the electrical properties of an organic photovoltaic cell. Experiments with four-point probe method and atomic force microscope revealed the lowest surface resistance of 17.64 ${\Omega}$/sq and the lowest average surface roughness of 1.39 nm at the plasma treatment power of 250 W. A device structure of ITO/CuPc/$C_{60}$/BCP/$Cs_2CO_3$/Al was fabricated by thermal evaporation with and without the plasma treated ITO substrate. It was found that the power conversion efficiency of the cell with the plasma treated ITO is 65 % higher than the one without the plasma treated ITO.

• Journal of the Korean institute of surface engineering
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• v.49 no.1
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• pp.87-91
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• 2016

The development of high performance transparent electrode with flexibility have been required for flexible electronics. Here, we demonstrate the silver nanowire and reduced graphene oxide hybrid transparent electrode for replacing brittle indium-tin-oxide electrode by spray coating technique and plasma reduction. The spray coating system is applied to deposit silver nanowire and over coated graphene oxide films and it has a great potential to scale-up. The resistance of silver nanowire transparent electrode is reduced by 10% and the surface roughness is decreased after graphene oxide coating. The over-coated graphene oxide is successfully reduced by $H_2$ plasma treatment and it is effective in increasing the environmental stability of electrode. The lifetime of silver nanowire and reduced graphene oxide hybrid electrode at $85^{\circ}C$ of Celsius degree of temperature and 85% of relative humidity has much increased.