• Korean Journal of Metals and Materials
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• v.47 no.10
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• pp.629-634
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• 2009

The effects of processing parameters on the surface properties of the hardened layers processed by the low temperature plasma nitrocarburizing and the low temperature two-step plama treatment (carburizing+nitriding) were investigated. The nitrogen-enriched expanded austenite structure (${\gamma}_N$) or S phase was formed on all of the treated surface. The surface hardness reached up to 1200 $HV_{0.025}$, which is about 5 times higher than that of untreated sample (250 $HV_{0.1}$). The thickness of hardened layer of the low temperature plasma nitrocarburized layer treated at $400^{\circ}C$ for 40 hour was only $15{\mu}m$, while the layer thicknesss in the two-step plama treatment for the 30 hour treatment increased up to about $30{\mu}m$. The surface thickness and hardness increased with increasing treatment temperature and time. In addition, the corrosion resistance was enhanced than untreated samples due to a high concentration of N on the surface. However, higher treatment temperature and longer treatment time resulted in the formation of $Cr_2N$ precipitates, which causes the degradation of corrosion resistance.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07a
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• pp.147-150
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• 2002

The electron field emission properties of amorphous carbon (a-C) films deposited using a RF magnetron sputtering system have been improved by introducing a simple method of argon plasma treatment at room temperature. Surface morphologies and structural properties of the a-C films were investigated by scanning electron microscopy and Raman spectroscope, respectively. Structural properties and surface morphologies of the a-C films were changed by argon plasma treatment. The emission properties improved with the plasma treatment.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.11 no.3
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• pp.203-207
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• 1998

After etching Al-Cu alloy films using $SiCl_4/Cl_2/He/CHF_3$ plasma, a corrosion phenomenon on the metal surface has been studied with XPS (X-ray photoelectron spectroscopy) and SEM (Scanning electron microscopy). In Al-Cu alloy system, the corrosion occurs rapidly on the etched surface by residual chlorine atoms. To prevent the corrosion, the $SF_6$ plasma treatment subsequent to the etch has been carried out. A passivation layer is formed by fluorine-related compounds on etched Al-Cu alloy surface after $SF_6$ treatment, and the layer suppresses effectively the corrosion on the surface as the RF power of $SF_6$ treatment increases. The corrosion could be suppressed successfully with $SF_6$ treatment in the RF power of 150watts.

• Journal of the Korean Society for Heat Treatment
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• v.17 no.4
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• pp.236-240
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• 2004

Effect of plasma power on PECVD process were investigated in this study. TiN and TiCN films were deposited on nitrided STD11 steel with 600W, 1,200W and 1,600W plasma power. As the plasma power was increased, the preferred orientation was reinforced from (200) to (111) and the hardness of films was improved. The low plasma power was, however, effective for improving of adhesion force of films. Regarding above properties, TiN and TiCN films were deposited by gradient plasma power. It was possible to get high hardness as well as adhesion force through gradient plasma power.

• Food Engineering Progress
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• v.22 no.4
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• pp.386-391
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• 2018

Effects of a commercial scale intervention system combining ultraviolet (UV)-C and plasma treatments on the microbial decontamination of black pepper powder were investigated. The process parameters include treatment time, time for plasma accumulation before treatment, and water activity of black pepper powder. A significant reduction in the number of indigenous aerobic mesophilic bacteria in black pepper powder was observed after treatments lasted for ${\geq}20min$ (p<0.05) and the reduction was differed by powder manufacturer. The microbial reduction rates obtained by individual UV-C treatment, individual plasma treatment, and UV-C/plasma-combined treatment were 0.2, 0.5, and 1.0 log CFU/g, respectively, suggesting that the efficacy of the microbial inactivation was enhanced by treatment combination. Nonetheless, neither plasma accumulation time nor powder water activity affected the microbial inactivation efficacy of the combined treatment. The UV-C/plasma-combined treatment, however, decreased lightness of black pepper powder, and the decrease generally increased as operation time increased. The plasma accumulation time of 20 min resulted in significant reduction in both lightness and brown color. The results indicate that the commercial-scale intervention system combining treatments of UV-C and plasma has the potential to be applied in the food industry for decontaminating black pepper powder.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.253.1-253.1
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• 2014

Plasma technology has been widely used for decontamination, differentiation, and disease treatment. Recently, studies show that plasma has effects on increasing seed germination and plant growth. In spite of increasing number of studies about plasma effects, the interaction between plasma and plants has been rarely informed. In this study, we have analyzed the effects of nonthermal atmospheric pressure plasma on seed germination and growth of coriander (Coriandum sativum), a medicinal plant. We used to Ar, air, and N2 plasma on seed as feeding gases. Plasma was discharged at 0.62 kV, 200 mA, 9.2 W. Seed germination was increased over time when treated with N2 based DBD plasma for exposure times of 30 seconds and 1 minute, everyday. After 7 days, about 80~100% of seeds were germinated in the treatment with N2 based DBD plasma, compared to control (about 40%, only gas treated seeds). In order to elucidate the mechanism of increased germination, we have analyzed characteristics of changes in plant hormones and seed surface structure by SEM.

• Proceedings of the Materials Research Society of Korea Conference
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• 2007.05a
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• pp.24.1-24.1
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• 2007

• Journal of the Korean Society for Heat Treatment
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• v.20 no.5
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• pp.259-269
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• 2007

• Elastomers and Composites
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• v.47 no.4
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• pp.310-317
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• 2012

A jute fiber surface was modified with argon gas in a cylinder type RF plasma generator to enhance the interfacial bond strength and to optimize the plasma treatment condition. The plasma power, gas pressure, and treat time were varied to figure out any effect of those parameters on the morphology and mechanical strength of jute fibers, and the interfacial bond strength for a model composite with polypropylene resin. As the severity of plasma treatment was increased, the surface of jute fibers became rougher. Gas pressure was less effective in roughening of the surface compared with those of treat time and plasma power. Approximately 25% drop in tensile strength of jute fibers was observed for the parameters of treat time and plasma power, while little deterioration was found for gas pressure, with increasing the severity. Based on the interfacial shear strength (IFSS), the optimum plasma treatment condition was determined to be treat time of 30 s, plasma power of 40 W, and gas pressure of 30 mTorr.

• Korean Journal of Acupuncture
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• v.18 no.1
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• pp.65-80
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• 2001

Effects of $LR_3$(太衝), $GB_{39}$(懸鍾) and $SP_4$(公孫) acupuncture on lipid composition were investigated in rat fed high fat diet. The results obtained from this study are as follows : 1. In the all treatment groups, the body weight values after feeding the basal diet for 4 weeks were significantly decreased compared to the initial body weight. However the decrement of body weight showed a high in acupuncture groups compared to those of control group. In the acupuncture groups, the decrement of body weight showed a high in the $LR_3$ acupuncture groups. 2. The contents of plasma ${\beta}$-lipoprotein and free fatty acids showed a tendency to decrease in the acupuncture groups compared to those of control group and the values of $LR_3$ acupuncture groups showed a low in the acupuncture groups. 3. The contents of plasma triglyceride showed a low values in the complex treatment group of $LR_3,\;GB_{39}$ and $SP_4$. However among the other treatment groups, this values showed no significantly different. The contents of liver triglyceride showed a tendency to decrease in all acupuncture groups except to the complex treatment group of $GB_{39}$ and $SP_4$ acupuncture and in the acupuncture groups, $LR_3$ acupuncture groups were lower than $GB_{39}$ and $SP_4$ acupuncture groups. 4. The contents of plasma glucose showed a tendency to decrease by the acupuncture treatment and $LR_3$ acupuncture groups showed a lower values than other acupuncture groups. 5. In the values of plasma glutamic oxaloacetate transferase activity, $LR_3$ acupuncture group and the complex treatment group of $LR_3,\;GB_{39}$ and $SP_4$ acupuncture were a lower values than other treatment groups and among the other treatment groups showed no significantly different. The values of plasma glutamic pyruvate transferase activity showed no significantly different among all the treatment groups. 6. Contents of plasma and liver total cholesterol showed a tendency to decrease in $LR_3$ acupuncture groups. However those of the other groups showed no significantly different. 7. In the contents of plasma LDL-cholesterol, $LR_3$ acupuncture groups were a lower values than other groups, however among the other groups showed no significantly different. The contents of plasma HDL-cholesterol showed a tendency to increase in the acupuncture groups, however these values showed no significantly different.