• Journal of the Korean Ceramic Society
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• v.38 no.7
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• pp.602-607
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• 2001

Zirconia powder containing 3 mol% yttria (3Y-PSZ) was casted on the cast iron substrate by plasma spraying method. Coated specimens were then heat treated at 500$\^{C}$ in nitrogen plasma. Wear tests were performed on nitrogen heat treated and non heat treated samples at temperatures from 25$\^{C}$ to 600$\^{C}$. Wear results showed that the friction coefficient and the wear loss of both the treated and the non-treated samples showed maximum value at 400$\^{C}$. These results were explained by low temperature thermal degradation due to the monoclinic transformation. Nitrogen plasma treatment significantly improved the tribological performance. The effect of nitrogen heat treatment on tribological behavior was explained by the increased micro-hardness and decreased monoclinic faction.

• Medical Lasers
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• v.8 no.2
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• pp.74-79
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• 2019

Periorbital melasma is often refractory to treatment and highly associated with rebound hyperpigmentation or mottled hypopigmentation after laser treatment in Asian patients. In this report, we describe 2 patients with cluster-1 periorbital melasma and 1 patient with cluster-2 periorbital melasma who experienced remarkable clinical improvements after microwave-generated, atmospheric-pressure, non-thermal nitrogen plasma treatments. All patients exhibited limited clinical responses after combination treatments with topical bleaching agents, systemic oral tranexamic acid, and low-fluenced Q-switched neodymium (Nd):yttrium-aluminum-garnet (YAG) lasers. Low-energy nitrogen plasma treatment at 0.75 J elicited remarkable clinical improvement in the periorbital melasma lesions without post-laser therapy rebound hyperpigmentation and mottled hypopigmentation. We deemed that a single pass of nitrogen plasma treatment at 0.75 J induces mild microscopic thermal tissue coagulation and modification within the epidermis while preserving the integrity of the basement membrane in patients with periorbital melasma. Accordingly, nitrogen plasma-induced dermal tissue regeneration could play a role in the treatment of melasma lesions.

• Medical Lasers
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• v.8 no.1
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• pp.28-31
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• 2019

Superficial fungal infections with dermatophytes, nondermatophyte molds, or yeasts are treated primarily with topical and/or systemic antifungal agents. Additional or alternative treatment modalities, particularly energy-delivering modalities, however, are used widely to induce fungicidal effects via selective photothermal reactions. In addition to light- or laser-based devices, plasma therapy also has antifungal properties. This report describes a Korean male patient with mycologically confirmed tinea pedis that was treated effectively with two sessions of nitrogen plasma treatment at one-week intervals using a plasma delivering system. Nitrogen plasma was prepared by loading a 0.28-ml inert nitrogen gas/pulse that was activated by a microwave generator. The other treatment settings were a nozzle diameter of 5 mm, pulse energy of 0.75 J, pulse duration of 7 msec, and two passes. One week after the first session of nitrogen plasma treatment, the patient exhibited marked reductions in scale and inflammation. One month after the final treatment, no clinical features of recurrence were found, and successive potassium hydroxide testing revealed negative results.

• Journal of the Korean institute of surface engineering
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• v.48 no.4
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• pp.163-168
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• 2015

Graphene has attracted much attention due to its remarkable physical properties and potential applications in many fields. In special, the electronic properties of graphene are influenced by the number of layer, stacking sequence, edge state, and doping of foreign elements. Recently, many efforts have been dedicated to alter the electronic properties by doping of various species, such as hydrogen, oxygen, nitrogen, ammonia and etc. Here, we report our recent results of plasma doping on graphene. We prepared mechanically exfoliated graphene, and performed the plasma treatment using ammonia gas for nitrogen doping. The direct-current plasma system was used for plasma ignition. The doping level was estimated from the number of peak shift of G-band in Raman spectra. The upshift of G-band was observed after ammonia plasma treatment, which implies electron doping to graphene.

• Journal of the Korean Society for Heat Treatment
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• v.23 no.3
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• pp.150-155
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• 2010

Generally, plasma nitriding process has composed with a nitriding layer within glow discharge region occurred by energy exchange. The dissociations of nitrogen molecules are very difficult to make neutral atoms or ionic nitrogen species via glow discharge area. However, the captured electrons in which a double-folded screen with same potential cathode can stimulate and come out some single atoms or activated ionic species. It was showed an important thing that is called "hat is a dominant component in this nitriding process?" in plasma nitriding process and it can take an effective species for without compound layer. During a plasma nitriding process, it was able to estimate with analyzing and identification by optical emission spectroscopy (OES) study. And then we can make comparative studies on the nitrogen transfer with plasma nitriding and ATONA process using plasma diagnosis and metallurgical observation. From these observations, we can understand role of active species of nitrogen, like N, $N^+$, ${N_2}^+$, ${N_2}^*$ and $NH_x$-radical, in bulk plasma of each process. And the same time, during DC plasma nitriding and other processes, the species of FeN atom or any ionic nitride species were not detected by OES analyzing.

• Journal of the Korean Society for Heat Treatment
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• v.12 no.2
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• pp.117-128
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• 1999

This study was carried out to investigate the surface characteristics of SCM440 steel nitrided with various nitrogen contents for 7 hours at $520^{\circ}C$ by using micro-pulse plasma nitriding apparatus of hot wall type. The effects of oxidation treatment was also investigated on plasma nitrided in 30% nitrogen and post oxidized SCM440 steel at $500^{\circ}C$ in $H_2O$ atmosphere. The ${\gamma}^{\prime}-Fe_4N$ and ${\varepsilon}-Fe_{2-3}N$ phases were detected in compound layer of the nitrided steel. As the content of nitrogen in plasma gas increased with 30, 50, 70% on the micro-pulse plasma nitriding for SCM440 steel, the thickness of compound, diffusion layer and the surface hardness were increased. From the wear test results, the best wear resistance was appeared in the condition of ductile ${\gamma}^{\prime}-Fe_4N$ phase formed specimen at 30% nitrogen, whereas that of the treated with 50% and 70% nitrogen decreased owing to the exfoliation of brittle ${\varepsilon}-Fe_{2-3}N$ phase in the compound layer. On the nitrided and subsequently oxidized SCM440 steel, the surface layer consisted of $Fe_3O_4$, ${\gamma}^{\prime}-Fe_4N$, and ${\varepsilon}-Fe_{2-3}N$ phases. In these treatments, the dissolution of nitrides affect hardness and hardening depth in compound and diffusion layers. For the nitrided in 30% nitrogen and post oxidized specimen at $500^{\circ}C$ for 1 hour, the wear resistance was lower than that of the only nitrided one in 30% nitrogen but higher than those of the nitrided ones in 50 and 70% nitrogen.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.27 no.1
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• pp.39-44
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• 2014

Silicon nitride thin film deposited with Plasma Enhanced Chemical Vapor Deposition was treated by a nitrogen plasma generated by Inductively Coupled Plasma at room temperature. The treatment was investigated by Fourier Transform Infrared Spectroscopy and Atomic Force Microscopy on the surface at various RF source powers at two RF bias powers. The amount of hydrogen was reduced and the surface roughness of the films was decreased remarkably after the plasma treatment. In order to understand the causes, we analyzed the plasma diagnostics by Optical Emission Spectroscopy and Double Langmuir Probe. Based on these analysis results, we show that the nitrogen plasma treatment was effective in the improving of the properties silicon nitride thin film for flexible display.

• Journal of Embryo Transfer
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• v.15 no.2
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• pp.115-120
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• 2000

This study was undertaken to test the hypothesis the hypothesis that treatment with hCG (5,000 IU) at the time of embryo transfer would enhance pregnancy rates in recipients, and the concentration of plasma urea nitrogen(PUN) in recipients was related to the effect of hCG on the reproductive performance. Blood samples were taken according to experimental condition for the assessment of the endogenous plasma progesterone concentration and plasma urea nitrogen. Concentrations of progesterone in plasma were higher in cows treated with hCG on day 7(estrus=day 0) than in those untreated during 7∼43 days after insemination. The pregnancy rates were 65.5 and 54.6% for the hCG treated and untreated groups, respectively. In recipient group categorized with PUN concentration of <12 mg/이, the pregnancy rates were 68.8 and 46.7% for the hCG treated and untreated groups, respectively. The results suggest that hCG treatment at 7 days after insemination could be used to increase the pregnancy rate of embryo transfer, and transfer, and only the recipients with PUN concentration of <12 mg/dl were influenced by treatment with hCG.

• Applied Chemistry for Engineering
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• v.33 no.1
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• pp.71-77
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• 2022

To increase biomass utilization, rice husk-based activated carbon (RHAC) followed by nitrogen plasma surface treatment was prepared and the electric double-layer capacitor performance was investigated. Through nitrogen plasma surface treatment, up to 2.17% of nitrogen was introduced to the surface of RHAC, and in particular the sample reacted for 5 min with nitrogen plasma showed dominant formation of pyrrolic/pyridine N functional groups. In addition, mesopores were formed on the RHAC material by the removal of silica, and the surface roughness of the carbon material increased by nitrogen plasma surface treatment, resulting in the formation of many micropores. As a result of cyclic voltammetry measurement, at a scan rate of 5 mV/s, the specific capacitance of the RHAC treated with nitrogen plasma increased up to 200 F/g, showing an 80.2% improvement compared to that of using untreated RHAC (111 F/g). This is attributed to the synergetic effect of the introduction of pyrrolic/pyridine-based nitrogen functional groups and the increase of the micropore volume on the surface of the carbon material. This study has a positive effect on the environment in terms of recycling waste resources and using plasma surface treatment.

• Applied Chemistry for Engineering
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• v.35 no.1
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• pp.8-15
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• 2024

In this study, nitrogen plasma treatment was performed in 5, 10, and 15 minutes to improve the tetracycline adsorption performance of activated carbon. All nitrogen plasma-treated activated carbons showed improved tetracycline adsorption compared to untreated activated carbons. The nitrogen functional groups in activated carbon lead to chemisorption with tetracycline via π-π interactions and hydrogen bonding. In particular, in the nitrogen plasma treatment at 80 W and 50 kHz, the activated carbon treated for 10 minutes had the best adsorption performance. At this time, the nitrogen content on the surface of the activated carbon was 2.03% and the specific surface area increased to 1,483 m²/g. As a result, nitrogen plasma treatment of activated carbon improved its physical and chemical adsorption capabilities. In addition, since the adsorption experimental results were in good agreement with the Langmuir isotherm and pseudo-second order model, it was determined that the adsorption of tetracycline on the nitrogen plasma-treated activated carbon was dominated by chemical adsorption through a monolayer. As a result, nitrogen plasma-treated activated carbon can be used as an adsorbent to efficiently remove tetracycline from water due to the synergistic effect of physical adsorption and proactive chemical adsorption.