• Journal of the Korean Society for Precision Engineering
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• v.20 no.8
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• pp.153-157
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• 2003

In the present work, the effect of plasma treatment of aluminum on the fracture toughness of CFRP/aluminum composites was investigated. The surface of the aluminum was treated by a DC plasma. The plasma treatment was carried out at volume ratio of acetylene gas to nitrogen gas of 5:5 and the treatment time used was 30 sec. Cracked lap shear specimens of aluminum/CFRP composites were made using secondary bonding procedure. Fracture toughness of aluminum/CFRP composites was determined using the work factor approach. Then, the fracture toughness of plasma-treated aluminum/CFRP composites was compared with that of untreated aluminum/CFRP composites. The results showed that the fracture toughness of plasma-treated aluminum/CFRP composites was about 50 % higher than that of untreated aluminum/CFRP composites.

• Applied Chemistry for Engineering
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• v.33 no.6
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• pp.624-629
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• 2022

Formaldehyde is an indoor pollutant that is harmful to humans, such as causing respiratory and skin diseases. Nitrogen plasma treatment was performed to introduce nitrogen groups on the surface of the activated carbon fibers (ACFs), and the adsorption characteristics of formaldehyde for the surface-modified ACFs were considered. As the nitrogen gas flow rate increased, the content of nitrogen functional groups introduced to the surface of the ACFs increased by about 7%, and the ratio of nitrogen functional groups to each type present was similar. Ultramicropores increased on the ACFs surface due to the etching effect of plasma treatment. The adsorption efficiency of formaldehyde on the modified ACFs surface was also enhanced. However, under the nitrogen flow rate of 120 sccm or more, the surface of the ACFs was excessively etched, and the specific surface area and the formaldehyde adsorption capacity decreased. Therefore, the content of the nitrogen groups is the main factor in the adsorption of formaldehyde on the nitrogen plasma-treated ACFs, but it can be found that the adsorption efficiency of formaldehyde is improved when the ACFs have a suitable pore structure.

• Journal of the Korean Society of Combustion
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• v.22 no.1
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• pp.23-31
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• 2017

Large-scale fuel tanks emit massive amount of hardly-combustible VOC mixtures which are light hydrocarbon species in dilution with nitrogen and carbon dioxide. We have developed a lab-scale burner to combust those VOC mixtures by use of a turbulent partially-premixed flame as a pilot flame. For a higher HC treatment ratio, the mixture gases were reformed by a rotating arc plasma device. The results showed that the nitrogen mole fraction and the injecting speed of the VOC mixture influence on the performance of the burner. It was also found that the size of the pilot flame and the power supplied to the plasma device determine the overall HC treatment ratio and the concentrations of CO and NOx in the exhaust gas.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.401-404
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• 2003

This paper investigates the effect of plasma treatment of aluminum on the fracture toughness of aluminum/CFRP composites, The surface of the aluminum panel was treated by a DC plasma. The plasma treatment was carried out at volume ratio of acetylene gas to nitrogen gas of 5:5 and the treatment times used was 30 sec. The fracture toughness of plasma-treated aluminum/CFRP' composites was compared with that of untreated aluminum/CFRP composites and The fracture surface of aluminum/CFRP composites was compared with SEM. The results showed that fracture toughness of plasm-treated aluminum/CFRP composites was about 50% higher than that of untreated aluminum/CFRP composites.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.12
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• pp.1332-1336
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• 2004

Amorphous carbon (a-C) films have been deposited on Si(100) substrate using RF magnetron system in order to investigate the electron field emission properties. The a-C films were treated by $N_2$ gas plasma at room temperature. Surface morphologices and structural properties of the a-C films before and after $N_2$ plasma treatment were observed by scanning electron microscopy and Raman spectroscope, respectively. Structural properties and surface morphology of the a-C films were changed by $N_2$ plasma treatment. The emission properties can be improved by the plasma treatment according to the contents of nitrogen on the a-C films which is varied by plasma treatment time. Before the plasma treatment, the a-C films are found to have a threshold field of 14 V/$\mu$m, but the a-C film treated by $N_2$ plasma for 30 min exhibit threshold field as low as 6.5 V/$\mu$m.

• Journal of the Korean institute of surface engineering
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• v.51 no.2
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• pp.133-137
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• 2018

Plasma devices such as jets, pencils, and torches have been developed as new tools that help penetration of target agents and applied to plasma medicine. However, these devices cannot be used in a large area. Therefore, we introduced a flexible plasma device, which can be treated of large area and designed as bendable plasma. In additional, in vitro model based on agarose gel was prepared that can be show effectiveness in the depth of penetration. Plasma treatment conditions such as power, time and distance can be optimized on the agarose gel wound model. The chemical structure of changed polysaccharides was predicted due to reactive excited atoms and molecules, UV photons, charged particles and reactive oxygen and nitrogen species (RONS).

• Polymer(Korea)
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• v.32 no.5
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• pp.433-439
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• 2008

An atmospheric plasma pre-treatment method was applied to polyurethane foam (density: 0.27) and rubber (butadiene rubber) to improve its contact angle and adhesion using atmospheric plate type reactor. In order to investigate the optimum reaction condition of plasma treatment, type of treatment gas (nitrogen, argon, oxygen, air), rate of gas flow ($30{\sim}100\;mL/min$), and treated time ($0{\sim}30\;s$) were examined in a plate plasma reactor. The result of the surface modification with respect to the treatment procedure was characterized by using SEM and ATR-FTIR. Due to a decrease of the contact angle of various materials, the greatest adhesion strength was achieved at optimum condition such as flow rate of 100 mL/min, reaction time of polyurethane foam 10 s and rubber 3 s for an atmosphere nitrogen gas. Consequently, the atmospheric plasma treatment reduced the wettability of the polyurethane foam and rubber also resulted in the improvement of the adhesion.

• Textile Coloration and Finishing
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• v.11 no.6
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• pp.1-6
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• 1999

The porosities of PET fibers were investigated using a nitrogen porosimeter according to oxygen plasma treatment and dyeing with a disperse dye, and they were discussed in terms of the change of internal micro-structure of the PET fiber. The total pore volume, surface area and average pore size of the plasma treated PET fibers increased expectably compared with the untreated sample. The PET fibers treated with oxygen plasma and then dyed with a disperse dye were increased significantly in the surface area and the total pore volume comparing with those of plasma treated only, but decreased in the average pore size. The increase of the surface area, after dyeing, of the plasma treated PET fibers was due to addition of the surface area of the dye itself to that of the PET fiber. The increase of the total pore volume of the plasma treated PET fibers by dyeing, which is the opposite result to the general idea that the pore volume of fibers would be reduced by occupation of dye molecules in the pores, could be explained by the free-volume model. This is that the amorphous region in the fiber expanded by occupation of dye molecules, and the marginal space surrounding dyes was generated as many smaller pores, and the decrease of the average pore size of the dyed sample also could be explained The decrease of the average pore size was caused by the splitting of a larger pore into smaller pores.

• Journal of Microbiology and Biotechnology
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• v.29 no.9
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• pp.1401-1411
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• 2019

Mycobacterial cell walls comprise thick and diverse lipids and glycolipids that act as a permeability barrier to antibiotics or other chemical agents. The use of OH radicals from a non-thermal plasma jet (NTPJ) for the inactivation of mycobacteria in aqueous solution was adopted as a novel approach. Addition of water vapor in a nitrogen plasma jet generated OH radicals, which converted to hydrogen peroxide ($H_2O_2$) that inactivated non-pathogenic Mycobacterium smegmatis and pathogenic Mycobacterium tuberculosis H37Rv. A stable plasma plume was obtained from a nitrogen plasma jet with 1.91 W of power, killing Escherichia coli and mycobacteria effectively, whereas addition of catalase decreased the effects of the former. Mycobacteria were more resistant than E. coli to NTPJ treatment. Plasma treatment enhanced intracellular ROS production and upregulation of genes related to ROS stress responses (thiolrelated oxidoreductases, such as SseA and DoxX, and ferric uptake regulator furA). Morphological changes of M. smegmatis and M. tuberculosis H37Rv were observed after 5 min treatment with $N_2+H_2O$ plasma, but not of pre-incubated sample with catalase. This finding indicates that the bactericidal efficacy of NTPJ is related to the toxicity of OH and $H_2O_2$ radicals in cells. Therefore, our study suggests that NTPJ treatment may effectively control pulmonary infections caused by M. tuberculosis and nontuberculous mycobacteria (NTM) such as M. avium or M. abscessus in water.

• Journal of Advanced Marine Engineering and Technology
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• v.32 no.2
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• pp.262-267
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• 2008

Plasma immersion ion beam (PIIB) nitriding process is an environmentally benign and cost-effective process, and offers the potential of producing high dose of nitrogen ions in a way of simple, fast and economic technique for the high plasma flux treatment of large surface area with nitrogen ion source gas. In this report PIIB nitriding technique was used for nitriding on austenite stainless steel of AISI304 with plasma treatment at $250{\sim}500^{\circ}C$ for 4 hours, and with the working gas pressure of $2.67{\times}10^{-1}$ Pa in vacuum condition. This PIIB process might prove the advantage of the low energy high flux of ion bombardment and enhance the tribological or mechanical properties of austenite stainless steel by nitriding, Furthermore, PIIB showed a useful surface modification technique for the nitriding an irregularly shaped three dimensional workpiece of austenite stainless steel and for the improvement of surface properties of AISI 304, such as hardness and strength