This study was carried out to investigate the effect of chlorine water and plasma gas treatment on the quality and microbial control of Latuca indica L. baby Leaf during storage. Latuca indica L. baby leaves were harvested from a plant height of 10cm. They were sterilized with 100μL·L-1 chlorine water and plasma-gas (1, 3, and 6hours), and packaged with 1,300cc·m-2·day-1·atm-1 films and then stored at 8±1?and RH 85±5% for 25days. During storage, the fresh weight loss of all treatments were less than 1.0%, and the carbon dioxide and oxygen concentrations in packages were 6-8% and 16-17%, respectively for all treatments in the final storage day. The concentration of ethylene in the packages fluctuated between 1-3μL·L-1 during the storage and the highest concentration of ethylene was observed at 6 hours plasma treatment in the final storage day. The off-odor of all treatments were almost odorless, the treatments of chlorine water and 1 hour plasma maintained the marketable visual quality until the end of storage. Chlorophyll content and Hue angle value measured at the final storage day were similar to those measured before storage in chlorine water and 1 hour of plasma treatments. E. coli was not detected immediately after sterilization in all sterilization treatments. After 6 hours of plasma treatment, the total bacteria fungus counts were lower than the domestic microbial standard for agricultural product in all sterilization treatments. The total aerobic counts in the end storage day increased compared to before storage, whereas E. coli was not detected in all sterilization treatments. The sterilization effect against bacteria and fungi was the best in chlorine water treatment. Plasma treatment showed sterilization effects, but within a prolonged period of time. In addition, the sterilization effect decreased gradually. These results suggest that chlorine water and plasma treatment were effective in maintaining Latuca indica L. baby Leaf commerciality and controlling microorganisms during postharvest storage.

Tin dioxide nanoparticles are prepared using a newly developed synthesis method of plasma-assisted electrolysis. A high voltage is applied to the tin metal plate to apply a high pressure and temperature to the synthesized oxide layer on the metal surface, producing nanoparticles in a low concentration of sulfuric acid. The particle size, morphology, and size distribution is controlled by the concentration of electrolytes and frequency of the power supply. The as-prepared powder of tin dioxide nanoparticles is used to fabricate a gas sensor to investigate the potential application. The particle-based gas sensor exhibits a short response and recovery time. There is sensitivity to the reduction gas for the gas flowing at rates of 50, 250, and 500 ppm of H2S gas.

We fabricate fine (<20 μm) powders of Bi0.5Sb1.5Te3 alloys using a large-scale production method and subsequently consolidate them at temperatures of 573, 623, and 673 K using a spark plasma sintering process. The microstructure, mechanical properties, and thermoelectric properties are investigated for each sintering temperature. The microstructural features of both the powders and bulks are characterized by scanning electron microscopy, and the crystal structures are analyzed by X-ray diffraction analysis. The grain size increases with increasing sintering temperature from 573 to 673 K. In addition, the mechanical properties increase significantly with decreasing sintering temperature owing to an increase in grain boundaries. The results indicate that the electrical conductivity and Seebeck coefficient (217 μV/K) of the sample sintered at 673 K increase simultaneously owing to decreased carrier concentration and increased mobility. As a result, a high ZT value of 0.92 at 300 K is achieved. According to the results, a sintering temperature of 673 K is preferable for consolidation of fine (<20 μm) powders.

Odor compounds and air-born microorganisms are simultaneously emitted from various aeration processes such as aerobic digestion, food-waste compositing, and carcass decomposition facilities that are biologically-treating wastes with high organic contents. The air streams emitted from these processes commonly contain sulfur-containing odorous compounds such as hydrogen sulfide(H2S) and bacterial bioaerosols. In this study, a wet-plasma method was applied to remove these air-born pollutants and to minimize safety issues. In addition, the effects of a gas retention time and a liquid-gas ratio were evaluated on removal efficiencies in the wet-plasma system. At the gas reaction time of 1.8 seconds and the liquid-gas ratio of 0.05 mLaq/Lg, the removal efficiency of bioaerosol was approximately 75 %, while the removal efficiency of H2S was lower than 20 %, indicating that the gaseous compound was not effectively oxidized by the plasma reaction at the low liquid addition. When the liquid-gas ratio was increased to 0.25 mLaq/Lg, the removal efficiencies of both H2S and bioaerosol increased to greater than 99 %. At the higher liquid-gas ratio, more ozone was generated by the wet-plasma reaction. The ozone generation was significantly affected by the input electrical energy, and it needed to be removed before discharged from the process.

Researches on the elimination of sulfur and nitrogen oxides with catalysts and absorbents reported many problems related with elimination efficiency and complex devices. In this study, decomposition efficiency of harmful gases was investigated. It was found that the efficiency rate can be increased by moving the harmful gases together with SPCP reactor and the catalysis reactor. Calcium hydroxide(Ca(OH)2), CaO, and TiO2 were used as catalysts. Harmful air polluting gases such as SO2 were measured for the analysis of decomposition efficiency, power consumption, and voltage according to changes to the process variables including frequency, concentration, electrode material, thickness of electrode, number of electrode winding, and additives to obtain optimal process conditions and the highest decomposition efficiency. The standard sample was sulfur oxide(SO2). Harmful gases were eliminated by moving them through the plasma generated in the SPCP reactor and the Ca(OH)2 catalysis reactor. The elimination rate and products were analyzed with the gas analyzer (Ecom-AC,Germany), FT-IR(Nicolet, Magna-IR560), and GC-(Shimazu). The results of the experiment conducted to decompose and eliminate the harmful gas SO2with the Ca(OH)2 catalysis reactor and SPCP reactor show 96% decomposition efficiency at the frequency of 10 kHz. The conductivity of the standard gas increased at the frequencies higher than 20 kHz. There was a partial flow of current along the surface. As a result, the decomposition efficiency decreased. The decomposition efficiency of harmful gas SO2 by the Ca(OH)2 catalysis reactor and SPCP reactor was 96.0% under 300 ppm concentration, 10 kHz frequency, and decomposition power of 20 W. It was 4% higher than the application of the SPCP reactor alone. The highest decomposition efficiency, 98.0% was achieved at the concentration of 100 ppm.

목적: 플라즈마 표면처리가 불화규소 아크릴레이트 재질의 RGP 콘택트렌즈의 물리화학적 특성에 미치는 영향을 분석하였다. 방법: RGP 렌즈 표면의 플라즈마 처리는 공기 중 상온에서 200 W로 수행하였으며, 처리시간은 0∼250초로 다르게 하였다. 습윤성을 평가하기 위해 접촉각을 측정하였다. 표면 성분은 X-선광전자분광분석기(XPS)로 관찰하고, 플라즈마 처리에 의한 실리케이트의 형성을 분석하였다. 표면의 형상과 거칠기는 원자현미경(AFM)으로 관찰하였다. 산소침투성의 변화는 전기분해 분석법으로 얻은 렌즈의 투과 전류값과 중심두께를 측정하여 비교하였다. 결과: 플라즈마로 표면 처리되면 초기에 접촉각이 급격히 감소하였으며, 처리되지 않은 표면에 비해 30%까지 감소하였다. 표면 성분의 탄소와 불소는 70% 이하로 감소했으나, 산소와 실리콘은 150% 이상 증가하였다. 표면에서 탄소가 감소하는 형태는 접촉각의 변화와 직접적으로 관계가 있었다. 플라즈마 표면처리에 의해 표면의 탄소와 불소는 휘발하고, 유리된 실리콘이 산소와 결합하여 표면에 친수성 실리케이트(SiOx, x=1.5∼2.0)가 형성되며, 실리케이트는 50% 이상 크게 증가하였다. 플라즈마 처리된 표면에서 원형이나 직각형의 돌출부가 관찰되고, 거칠기(RMS)는 40% 이상 증가하였다. 결론: RGP 콘택트렌즈를 공기 중에서 플라즈마 처리하면 표면에 친수성인 실리케이트가 형성되어 습윤성은 개선되지만 산소침투성에는 영향을 주지 않았다. 습윤성의 증가는 표면형상의 변화보다는 실리케이트의 형성이 더 큰 영향을 준 것으로 판단되었다. 또한 플라즈마 처리에 의해 표면에 국한되어 형성된 실리케이트가 열린 구조를 갖고 있어 산소침투성에 유의한 변화가 없었던 것으로 생각된다.

Fe based (FeCSiBPCrMoAl) amorphous powder, which is a composition of iron blast cast slag, were produced by a gas atomization process, and sequently mixed with ductile Cu powder by a mechanical ball milling process. The Fe-based amorphous powders and the Fe-Cu composite powders were compacted by a spark plasma sintering (SPS) process. Densification of the Fe amorphous-Cu composited powders by spark plasma sintering of was occurred through a plastic deformation of the each amorphous powder and Cu phase. The SPS samples milled by AGO-2 under 500 rpm had the best homogeneity of Cu phase and showed the smallest Cu pool size. Micro-Vickers hardness of the as-SPSed specimens was changed with the milling processes.

Fe based (FeCSiBPCrMoAl) amorphous powder, which is a composition of iron blast cast slag, were produced by a gas atomization process, and sequently mixed with ductile Cu powder by a mechanical ball milling process. The experiment results show that the as-prepared Fe amorphous powders less than 90 m in size has a fully amorphous phase and its weight fraction was about 73.7%. The as-atomized amorphous Fe powders had a complete spherical shape with very clean surface. Differential scanning calorimetric results of the as-atomized Fe powders less than 90 m showed that the glass transition, T, onset crystallization, T, and super-cooled liquid range T=T-T were 512, 548 and 36, respectively. Fe amorphous powders were mixed and deformed well with 10 wt.% Cu by using AGO-2 high energy ball mill under 500 rpm.

The microstructure, mechanical and electrochemical properties of plasma electrolytic coatings (PEO) coatings on Mg-4.3 wt%Zn-1.0 wt%Y and Mg-1.0 wt%Zn-2.0 wt%Y alloys prepared by gas atomization, followed by compaction at 320 for 10 min under the pressure of 700 MPa and sintering at 380 and 420 respectively for 24 h, were investigated, which was compared with the cast Mg-1.0 wt%Zn alloy. All coatings consisting of MgO and oxides showed porous and coarse surface features with some volcano top-like pores distributed disorderly and cracks between pores. In particular, the surface of coatings on Mg-1.0 wt%Zn-2.0 wt%Y alloy showed smaller area of pores and cracks compared to the Mg-4.3 wt%Zn-1.0 wt%Y and Mg-1.0 wt%Zn alloys. The cross section micro-hardness of coatings on the gas atomized Mg-Zn-Y alloys was higher than that on the cast Mg-1.0 wt%Zn alloy. Additionally, the coated Mg-1.0 wt%Zn-2.0 wt%Y alloy exhibited the best corrosion resistance in 3.5%NaCl solution. It could be concluded that the addition of Y has a beneficial effect on the formation of protective and hard coatings on Mg alloys by plasma electrolytic oxidation treatment.

Using Spark Plasma Sintering process (SPS), consolidation behavior of gas atomized alloys were investigated via examining the microstructure and evaluating the mechanical properties. In the atomized ahoy powders, fine particles were homogeneously distributed in the matrix. The phase distribution was maintained even after SPS at 723 K, although particles were newly precipitated by consolidating at 748 K. The density of the consolidated bulk Mg-Zn-Y alloy was . The ultimate tensile strength (UTS) and elongation were varied with the consolidation temperature.

Ni based() bulk metallic glass(BMG) powders were produced by a gas atomization process, and ductile Cu powders were mixed using a spray drying process. The Ni-based amorphous powder and Cu mixed Ni composite powders were compacted by a spark plasma sintering (SPS) processes into cylindrical shape. The relative density varied with the used SPS mold materials such as graphite, hardened steel and WC-Co hard metal. The relative density increased from 87% to 98% when the sintering temperature increased up to in the WC-Co hard metal mold.

우수한 열적, 화학적, 기계적 성질을 가진 폴리이미드 막의 표면을 Ar, NH3 플라즈마로 처리한 후 혼합기체(CO2/N2=20/80 vol%) 의 투과 실험을 통하여 플라즈마 처리 조건이 기체 투과도와 분리성능에 어떠한 영향을 미치는지를 조사하였다. 투과실험은 30℃, 5atm에서 variable volume method에 의해 행하여졌다. 표면개질된 폴리이미드 막의 투과거동에 대해 처리시간, 출력세기, 가스주입 유량 및 반응기 내의 압력과 같은 플라즈마 처리 조건의 영향을 조사하였다. 플라즈마 처리된 막의 표면은 FTIR-ATR, ESCA, AFM으로 분석하여 처리전후의 변화를 관찰하였다. 또한 플라즈마 처리시간에 따른 etching 효과와 흡수성은 weight loss와 contact angle를 측정하여 조사하였다. 그리고 투과 실험에 있어서 반응 온도의 변화에 따른 영향도 함께 연구되었으며, saturator를 이용한 dry 상태와 wet 상태에서 혼합가스에 대한 폴리이미드 막의 기체투과특성에 대한 실험 역시 수행되었다.

Composite membranes were prepared by the deposition of pentafluoropyridine(PFP) or pentafluorotoluene(PFT) plasma films onto porous Celgard and nonporous poly(dimethylsiloxane) [PDMS] films. Gas permeation measurements for the composite membranes were made in the temperature range of 35˚C to 75 ˚C and the solubilities in plasma polymers were measured using a Cahn Microbalance. The permeability coefficients of plasma polymers obeyed the Arrhenius relationship fairly wall. Activation energies for permeation in the plasma films increased with the size of penetrant molecules. The activation energy of plasma polymers was much lower than that of commonly used perfluoropolymers. This difference was proved to be attributable to the much lower heat of solutions of the plasma polymers compared to perfluoropolymers. The diffusion activation energies were comparable with each other.

본 연구에서는 고밀도 플라즈마를 형성하는 planar magnetron RF 플라즈마 CVD를 이용하여 DLC(diamond-like carbon) 박막을 합성하였다. 이 방법을 이용하여 DLC 박막을 합성한다면 고밀도 플라즈마 때문에 종래의 플라즈마 CVD(RF-PECVD)법보다 증착속도가 더욱더 향상될 것이라는 것에 착안하였다. 이를 위해 magnetron에 의한 고밀도 플라즈마가 존재할 때도 역시 DLC박막형성에 미치는 RF 전력과 반응가스 압력이 중요한 반응변수인가에 대해 조사하였고, 일정한 자기장의 세기에서 RF전력과 DC self-bias 전압과의 관계를 조사하였다. 또한 RF전력변화에 따른 박막의 증착속도와 밀도를 측정하였다. 본 연구에 의해 얻어진 박막의 증착속도는 magnetron에 의한 이온화율이 매우 높아 기존의 RF-PECVD 법보다 매우 빠르며, DLC박막의 구조와 물질특성을 알아보기 위해 FTIR(fourier transform infrared)및 Raman 분광분석을 행한 결과 전형적인 양질의 고경질 다이아몬드상 탄소박막임을 알 수 있었다.

플라스마 고분자막을 통한 일반기체들(He, H2,CO2,O2,N2,CH4 등)의 투과특성을 조사하였으며 IR 분석을 통하여 플라즈마 고분자의 화학적 구조를 살펴 보았다. 플라즈마 고분자막은 불소를 함유한 방향족 화합물의 플라즈마 중합에 의하여 제조하였으며 이 막을 통한 기체투과실험은 35℃, 1기압에서 행하였다. 이 막들의 투과계수는 투과기체의 분자 크기가 커질수록 감소하는 경향을 나타내었다. 플라즈마 고분자의 O2/N2 선택투과도는 상용고분자보다 약간 낮았으나 CO2/CH4 선택투과도는 상용고분자보다 매우 높은 것으로 나타났다. FT-IR 분석을 통하여 플라즈마 고분자는 방향족과 지방족 구조를 모두 포함한 구조를 이루고 있다는 것을 알 수 있었다.

메탄가스를 반응가스로 하여 플라즈마 화학증착법으로 Diamondlike Carbon(DLC)박막 제작시 박막의 광학적 특성에 미치는 수소가스의 영향을 조사하였다. 수소가스를 보조가스로 사용하는 경우는 불활성가스인 아르곤이나 헬륭의 경우와는 달리 인가전력의 변화에 따라 수소가스의 역할이 다르게 나타났다. Optical band gap의 변화와 FT-IR 분석결과로부터 수소가스에 의한 C-H 결합의 화학적인 에칭과 스퍼터링 및 수소의 박막 내로의 주입 가능성을 예측하고 이를 아르곤과 헬륨을 보조가스로 사용한 경우와 비교하여 그 타당성을 확인하였다.