• 한국표면공학회지
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• 제36권1호
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• pp.69-73
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• 2003

The atmospheric pressure plasma is regarded as an effective method for surface treatments because it can reduce the period of process and doesn't need expensive vacuum apparatus. The performance of non-transferred plasma torches is significantly depended on jet flow characteristics out of the nozzle. In order to produce the high performance of a torch, the maximum discharge velocity near an annular gap in the torch should be maintained. Also, the compulsory swirl is being produced to gain the shape that can concentrate the plasma at the center of gas flow. In this work, the distribution of gas flow that goes out to atmosphere through a plenum chamber and nozzle is analyzed to evaluate the performance of atmospheric pressure plasma torch which can present the optimum design of the torch. Numerical analysis is carried out with various angles of an inlet flow velocity. Especially, three-dimensional model of the torch is investigated to estimate swirl effect. We also investigate the stabilization of plasma distribution. For analyzing the swirl in the plenum chamber and the flow distribution, FVM (finite volume method) and SIMPLE algorithm are used for solving the governing equations. The standard k-model is used for simulating the turbulence.

• 한국재료학회지
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• 제25권11호
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• pp.616-621
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• 2015

Atmospheric pressure plasma is used in the biological and medical fields. Miniaturization and safety are important in the application of apply atmospheric plasma to bio devices. In this study, we made a small, pocket-sized inverter for the discharge of atmospheric plasma. We used pulse power to control the neutral gas temperature at which the, when plasma was discharged. We used direct current of 5 V of bias(voltage). The output voltage is about 1 to 2 kilo volts the frequency is about 80 kilo hertz. We analyzsed the characteristics of the atmospheric plasma using OES(Optical emission spectroscopy) and the Current-Voltage characteristic of pulse power. By calculating of the current voltage characteristics, we were able to determine that, when the duty ratio increased, the power that actually effects the plasma discharge also increased. To apply atmospheric plasma to human organisms, the temperature is the most important factor, we were able to control the temperature by modulating the pulse power duty ratio. This means we can use atmospheric plasma on the human body or in other areas of the medical field.

• 한국재료학회지
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• 제21권10호
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• pp.532-541
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• 2011

The Xe plasma flat lamp, considered to be a new eco-friendly LCD backlight, requires a further improvement of its luminance and luminous efficiency. To improve the performance of this type of lamp, it is necessary to understand the effects of the discharge variables on the luminous characteristics of the lamp. In this study, the luminous characteristics of a coplanartype Xe plasma flat lamp with a teeth-type electrode pattern were analyzed while varying the gas composition, gas pressure and input voltage. The effects of the phosphor layer on the discharge and the luminous characteristics of the lamp were also studied. The luminous efficiency of the coplanar-type Xe plasma flat lamp improved as the Xe input ratio and gas pressure increased. Higher luminous efficiency was also obtained when helium (He) was used as a buffer gas and when a phosphor layer was fabricated on the electrode region. In contrast, the luminous efficiency was reduced with increasing the input voltage. It was found that the infrared emissions from the lamp were affected by the Xe excitation rate in the plasma, the Xe gas density, the collisional quenching of excited Xe species by gas molecules, and the recombination rate between the Xe ions and electrons.

• 한국연소학회지
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• 제10권4호
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• pp.24-32
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• 2005

Various types of plasma source applied in $CH_4$ decomposition process are compared. DBD by pulse and AC power, spark by pulse and AC power, rotating arc and hollow cathode plasma are chosen to be compared. The results show that $CH_4$ conversion per given unit power is relatively high in hollow cathode plasma and rotating arc that induces rather high temperature condition and that is why both thermal dehydration and plasma induced decomposition contribute for the overall process. In case of DBD wherein high temperature electron and low temperature gas molecule coexist, the process shows low conversion rate, for in rather low temperature condition the contribution of thermal dehydration is lowered. Selectivity of $C_2H_6$ and $C_2H_2$ is shown to be a good parameter of the relative contribution of plasma chemistry in the overall process. From the results we concluded that required condition of plasma source for a cost effective and high yield $CH_4$ decomposition is to have characteristics of both thermal plasma and non thermal plasma in which temperature is high above a certain threshold state for thermal dehydration and electron induced collision is maximized in the same breath.

• 한국식품영양학회지
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• 제15권4호
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• pp.350-356
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• 2002

표준 마요네즈 제조에 Bovine Plasma를 첨가하거나, 난황의 일부 혹은 전량을 Bovine Plasma으로 대체하여 마요네즈를 제조하고 점도, 색도, 유화 안정성, 관능검사를 통하여 Bovine Plasma의 마요네즈의 제조적성을 검토한 결과는 다음과 같다. 1. 점도는 표준 마요네즈(난황비율 12%) 제조 배합비에 0.01~0.1% Bovine Plasma를 첨가하였을 때 다소 증가하였고, 난황 첨가비를 50% 감소한 시료에서도 l~3% Bovine Plasma를 첨가함에 따라 표준 마요네즈와 근접 한 점도를 나타냈다. 난황을 전혀 첨가하지 않고 Bovine Plasma만으로 제조한 경우도 5% 첨가수준에서 표준 마요네즈에 근접한 점도를 나타냈다. 2. 색도의 측정결과, 난황의 비율(6, 12%)과 Bovine Plasma의 첨가비율에 따라 명도값을 나타내는 L값은 전체 시료간, 저장기간(3$0^{\circ}C$ 21일간)에 따른 큰 차이를 보이지 않았으나, 황색도를 나타내는b값은 난황의 비율에 따라 뚜렷한 차이를 보였고, Bovine Plasma의 첨가비율에 따른 차이는 보이지 않았다. 3. Bovine Plasma의 첨가가 유화 안정성에 미치는 영향(3$0^{\circ}C$ 21일간)을 검토한 결과, 표준 마요네즈에 Bovine Plasma를 첨가함에 따라 안정성이 증가하였고, 난황비율을 표준 마요네즈의 50%로 감소시켜도 1~3% Bovine Plasma를 첨가함에 따라 표준 마요네즈와 근접한 유화 안정성을 보였다. 난황을 전혀 첨가하지 않고 Bovine Plasma만으로 제조한 경우도 5% 첨가수준에서 표준 마요네즈와 근접한 유화 안정성을 나타냈다. 4. 관능검사에서 표준 마요네즈에 0.0l~0..1% Bovine Plasma를 첨가한 시료는 Bovine Plasma의 첨가비율에 따라 항목별로 다소 차이는 있었으나 전반적으로 낮은 기름냄새, 달걀냄새, 식초냄새, 기름맛, 달걀맛, 느끼한 맛, 식초맛을 나타내고, 냄새와 맛의 조화도가 높아 표준 마요네즈보다 선호되는 것으로 평가되었다. 또한, 난황의 첨가비율을 50 %로 감소시키고 l~3% Bovine Plasma를 첨가하여 제조한 마요네즈는 색을 제외하고는 모든 항목에서 표준 마요네즈와 유의적인 차이를 보이지 않았다. 반면에, 난황을 전혀 첨가하지 않고 5%의 Bovine Plasma만으로 제조한 마요네즈는 표준 마요네즈와 비교했을 때 다소 강한 기름냄새와 기름맛, 난황이 첨가되지 않아 색에 대한 기호도의 저하 등 관능적인 면에서 전반적으로 낮은 결과를 보였다.

• 한국염색가공학회지
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• 제16권6호
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• pp.30-34
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• 2004

Polyacrylontrile fiber was modified with argon low temperature plasma by RF glow discharge at 240 mTorr, 40 W to investigate the surface morphological changes and mechanical characteristics such as elongation, tenacity, and modulus. Analysis of the SEM images revealed that the plasma treatment resulted in significant ablation on the surfaces rendering a severe crack formation. The morphological changes were evident with short treatment time of argon plasma although longer treatment time damaged the surface more severely. The mechanical characteristics such as tenacity and elongation were deteriorated due to the plasma treatment. The tenacity of the fiber treated with argon-plasma for 5 min showed a decreased value up to 21.9 % when compared to the untreated fiber. While the corresponding initial modulus(0 - 1 %) increased markedly up to 44.3 %.

• 한국표면공학회지
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• 제36권2호
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• pp.206-213
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• 2003

Effects of plasma nitriding on the surface characteristics of tool steels have been investigated using wear tester, micro-hardness tester and scanning electron microscope (SEM) Commercial SKD 11 and SM45 alloy were used as specimens and were plasma nitrided using a plasma nitriding equipment for 5 hr and 10hr at $500^{\circ}C$. Microstructure and phase analysis were performed using SEM and XRD. It was found that plasma nitriding for lour at $500^{\circ}C$, compared with plasma nitriding for 10hr at $500^{\circ}C$, had a thick nitrided layer and produced a layer with good wear resistance and hardness as nitriding time increased. SKD11 alloy showed that wear resistance and hardness decreased, whereas surface roughness increased, compared with SM45 alloy.

• 반도체디스플레이기술학회지
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• 제17권4호
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• pp.27-31
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• 2018

The effect of $NH_3$ plasma passivation on the chemical and electrical characteristics of ALD HfAlO dielectric on the InGaAs substrate was investigated. The results show that $NH_3$ plasma passivation exhibit better electrical & chemical performance such as much lower leakage current, lower density of interface trap(Dit) level, and low unstable interfacial oxide. $NH_3$ plasma passivation can effectively enhance interfacial characteristics. Therefore $NH_3$ plasma passivation improved the HfAlO dielectric performance on the InGaAs substrate.

• 한국표면공학회지
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• 제57권3호
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• pp.155-164
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• 2024

Physical properties of carbon nanomaterials are dependent on their nanostructures and they are modified by diverse synthesis methods. Among them, thermal plasma method stands out for synthesizing carbon nanomaterials by controlling chemical and physical reactions through various design and operating conditions such as plasma torch type, plasma gas composition, power capacity, raw material injection rate, quenching rate, kinds of precursors, and so on. The method enables the production of carbon nanomaterials with various nanostructures and characteristics. The high-energy integration at high-temperature region thermal plasma to the precursor is possible to completely vaporize precursors, and the vaporized materials are rapidly condensed to the nanomaterials due to the rapid quenching rate by sharp temperature gradient. The synthesized nanomaterials are averagely in several nanometers to 100 nm scale. Especially, the thermal plasma was validated to synthesize low-dimensional carbon nanomaterials, carbon nanotubes and graphene, which hold immense promise for future applications.

• 한국표면공학회지
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• 제37권2호
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• pp.119-127
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• 2004

In order to develop the corrosion and wear resistance of stainless steels, effects of plasma-nitriding on the surface characteristics of stainless steels containing Nb were investigated by utilizing a potentiostat. It was found that plasma nitriding at $350^{\circ}C$, compared with $500^{\circ}C$, produced a good corrosion resistance as nitriding time increased, whereas stainless steel containing low Nb content showed that pitting potential and corrosion potential decreased.