• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.11
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• pp.1972-1977
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• 2007

Micro plasma has been recently studied to investigate the effects on various cells. We study a micro-plasma produced by a plasma needle that is operated with RF power and its effects on G361 melanoma cells. The micro plasma size ranges from sub-mm to several mm at a few watts of RF power. For the bio-medical treatment, low-temperature plasma is obtained and gas temperature is controlled within several tens of degrees $(^{\circ}C)$ in order not to disturb cell activities. Elementary spectroscopic studies to obtain plasma characteristics are presented for Ar and He plasma with different frequencies of RF power. Also the preliminary results of the micro plasma effects on G361 melanoma cells are presented. It was observed that the irradiation of micro plasma induces cell death through the deprivation of tyrosine phosphorylation in the G361 cells.

• Journal of the Microelectronics and Packaging Society
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• v.18 no.4
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• pp.11-18
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• 2011

The quantitative interfacial adhesion energy of the Cu-Cu direct bonding layers was evaluated in terms of the bonding temperature and Ar+$H_2$ plasma treatment on Cu surface by using a 4-point bending test. The interfacial adhesion energy and bonding quality depend on increased bonding temperature and post-annealing temperature. With increasing bonding temperature from $250^{\circ}C$ to $350^{\circ}C$, the interfacial adhesion energy increase from $1.38{\pm}1.06$ $J/m^2$ to $10.36{\pm}1.01$ $J/m^2$. The Ar+$H_2$ plasma treatment on Cu surface drastically increase the interfacial adhesion energy form $1.38{\pm}1.06$ $J/m^2$ to $6.59{\pm}0.03$ $J/m^2$. The plasma pre-treatment successfully reduces processing temperature of Cu to Cu direct bonding.

• Journal of the Korean Vacuum Society
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• v.13 no.4
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• pp.175-181
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• 2004

We investigated the stability of the DLC film coated on 304 stainless steel substrate by Radio frequency assisted chemical vapor deposition method. Fracture and spallation behaviour of the coating was observed during micro-tensile test of the fil $m_strate composite. As the tensile deformation progressed, the cracks of the film were observed in the perpendicular direction to the tensile axis. Further deformation resulted in the plastic deformation with $45^{\circ}$ slip bands on the substrate surface. Spallation of the film occurred with the plastic deformation, which was initiated at the cracks of the film and was aligned along the slip directions. We found that both the cracking and the spallation behaviors are strongly dependent on the pre-treatment condition, such as Ar plasma pre-treatment. The spallation of the film was considerably suppressed in an optimized condition of the substrate cleaning by Ar glow discharge. We observed the improved stability with increasing duration of Ar plasma pre-treatment.nt.

• Proceedings of the KIEE Conference
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• 2007.11a
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• pp.220-221
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• 2007

Micro plasma has been recently studied to investigate the effects on various cells. We study a micro-plasma produced by a plasma needle that is operated with RF power and its effects on G361 melanoma cells. The micro plasma size ranges from sub-mm to several mm at a few watts of RF power. For the bio-medical treatment, low-temperature plasma is obtained and gas temperature is controlled within several tens of degrees $(^{\circ}C)$ in order not to disturb cell activities. Elementary spectroscopic studies to obtain plasma characteristics are presented for Ar and He plasma with different frequencies of RF power. Also the preliminary results of the micro plasma effects on G361 melanoma cells are presented. It was observed that the irradiation of micro plasma induces cell death through the deprivation of tyrosine phosphorylation in the G361 cells.

• Journal of the Korean Vacuum Society
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• v.6 no.4
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• pp.359-363
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• 1997

We have investigated the surface characteristics of n-GaAs (100) treated with Ar plasma (40 W, 5~120 sec) by photoreflectance (PR) measurement. With increasing Ar plasma treatment time, the intensity of $E_0$ peak observed to the minimum at 5 sec. The surface electric field ($E_0$), net carrier concentration ($N_P-N_A$), and surface state density ($Q_{SS}$ are $1.05{\times}10^5V/cm$ and $1.31{\tiems}10^{17}cm^{-3}$ and $1.64{\times}10^{-7}C/m^2$, respectively. These values were about 57.1, 81.4 and 56.9% smaller than those of bulk n-GaAs. On the other hand, the concentration of compensation centers ($N_A$) was maximum with value of $5.75{\times}10^{17}cm^{-3}$ at 5 sec. And penetration depth of defects generated after treated with Ar plasma was about 450 $\AA$ from surface.

• Korean Journal of Materials Research
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• v.14 no.1
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• pp.52-58
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• 2004

The surface property and formation behavior of a boride layer formed on Ni-Cr-Mo steel in a plasma paste boronizing treatment were investigated. The plasma paste boronizing treatment was carried out at 973～1273 K for 1-7 hrs under the gas ratio of Ar:H$_2$ (2:1). The thickness of the boride layer increased with increasing temperature and time in the boronizing treatment. The cross-section of the boride layer was a tooth structure and the hardness was Hv 2000～2500. XRD analysis revealed that the compound was identified as FeB, $Fe_2$B, and mixed phase of FeB/$Fe_2$B in the boride layer formed at 973～1073 K, 1173K, and 1273K, respectively. The Ni-Cr-Mo alloy boronized at 1173-1273 K showed the best excellent wear resistance against the sand. As a results of corrosion test in 1 M $H_2$$SO_4$ solution, $Fe_2$B formed on the matrix alloy exhibited higher corrosion resistance than FeB.

• Korean Journal of Materials Research
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• v.13 no.9
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• pp.587-592
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• 2003

The thin films of 316L stainless steel were made on glass and S45C substrate by Ion beam assisted deposition with reactive atmosphere of argon and nitrogen. The films were deposited at the various conditions of ion beam power and the ratios of Ar/$N_2$gas. Properties of these films were analyzed by glancing x-ray diffraction method(GXRD), AES, potentiodynamic test, and salt spray test. The results of GXRD showed that austenite phase could be appeared by $N_2$ion beam treatment and the amount of austenite phase increased with the amount of nitrogen gas. The films without plasma ion source treatment had the weak diffraction peak of ferrite phase. But under the Ar plasma ion beam treatment, the strong diffraction peaks of ferrite phase were appeared and the grain size was increased from 12 to 16 nm. Potentiodynamic polarization test and salt spray test indicated that the corrosion properties of the STS 316L films with nitrogen ion source treatment were better than bulk STS 316L steel and STS 316L films with Ar ion source treatment.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.4
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• pp.632-637
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• 2003

In this study, the effect of surface treatment of CFRP and aluminum on the fracture toughness of CFRP/aluminum composites was investigated. CFRP was surface-treated by Ar$^{+}$ ion beam under oxygen environment, and the aluminum was surface-treated by DC plasma. CFRP was adhesively bonded to aluminum using the secondary bonding procedure. Cracked lap shear specimens were used to determine fracture toughness. Three cases of cracked lap shear specimens were made depending on the surface treatment. The values of fracture toughness of three cases were compared to each other It was found that the fracture toughness of ion beam-treated CFRP/aluminum composites was almost 72 % higher than that of unrented CFRP/aluminum composites. The fracture toughness of CFRP/plasma-treated aluminum composites was 50 % higher than that of untreated CFRP/aluminum composites.s.

• Journal of the Korean Vacuum Society
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• v.4 no.S2
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• pp.49-57
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• 1995

At present the processes of boronizing have been mostly studied in a plasma from gaseous compounds containing the impregnating element and are in an industrial use. These have been investigated by a variety of works in a glow discharge with different mixture ratios of $B_2H_6$ and $H_2$ as well as $BCl_3$ and $H_2$. The active atomosphere has been diluted by Ar or some other inert gas in order to enhance control of boron potential and to reduce the ignition voltage of the glow discharge. The Control of gaseous atomosphere is essential to a boride layer in plamsa boronizing treatment. The boride formation is required to make the workpiece surface saturated with boron content. The present study considers the efficiency of plasma boronizing reactions and the morphology of boride layer under various plasma conditions

• The Korea Journal of Herbology
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• v.26 no.4
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• pp.187-194
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• 2011

Objective : Astragali Radix (AR) and Cinnamomi Cortex (CC) are used to enhance immune response in Asian traditional medicine. Immuno-potentiation of the combination of AR and CC were evaluated on the cellular and humoral immune response using murine macrophage cell line (RAW 264.7) and OVA-immunized mice. Methods : This study was designed to investigate the immuno-potentiative effects of AR, CC, and AR with CC on nitric oxide synthesis in RAW 264.7 cells and proliferation and production levels of Intereukin-2 (IL-2) in mouse splenocytes. In addition, we evaluated the plasma-specific antibody responses and splenocyte proliferation on ovalbumin (OVA)-immunized mice treated with herbal extracts. Results : Combination treatment with AR and CC increased nitric oxide synthesis in RAW 264.7 cells and IL-2 level in splenocytes (p<0.001). Combination of AR and CC significantly enhanced the Concanavalin A- (Con A ; T cell mitogen) and lipopolysaccharide-(LPS ; B cell mitogen) induced splenocyte proliferation on the OVA-immunized mice. Combination of AR and CC also significantly enhanced plasma levels of OVA-specific IgG (p<0.01), IgG1 (p<0.05) and total IgM (p<0.01) compared with the OVA-immunized control group. Conclusion : These results suggest that combination of AR and CC could be used as therapeutic profile on activation of immune response.