• Proceedings of the Korean Institute of Surface Engineering Conference
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• 1999.05a
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• pp.41-42
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• 1999

• 한국전자현미경학회:학술대회논문집
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• 2003.11a
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• pp.41-42
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• 2003

• Proceedings of the Materials Research Society of Korea Conference
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• 1995.11a
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• pp.131-132
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• 1995

• Journal of Microbiology and Biotechnology
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• v.14 no.2
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• pp.363-366
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• 2004

In order to obtain an industrial strain with higher L(+)-lactic acid yield, the wild type strain Rhizopus oryzae PW352 was mutated by means of Nitrogen ions implantation (l5 Kev, $7.8 \times 10^{14} - 2.08 \times 10^{15} ions/Cm^2$ and two mutants RE3303 and RF9052 were isolated. After 36 h shake-flask cultivation, the concentration of L(+)-lactic acid reached 131-136 g/l, the conversion rate of glucose was as high as 86%-90% and the productivity was 3.61 g/l.h. It was almost a 75% increase in lactic acid production compared with the wild type strain. Maximum fermentation temperature of RF9052 was increased to $45^{\circ}C$ from original $36^{\circ}C$. At the same time, the preferred range of fermentation temperature of RF9052 was broadened compared with PW352.

• Korean Journal of Medicinal Crop Science
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• v.7 no.1
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• pp.1-6
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• 1999

Basic informations for direct somatic embryo formation in Rehmannja glutinosa Lib. were obtained in 500ml erlenmyer flask. The ratio of ammonium to nitrate nitrogen of 825(mg/l) : 1900(mg/l) was proper condition for somatic embryo formation from stem and petiole explants and 3% sucrose was the most effective carbon source. Full strength MS medium with 2mg/l BA was better than LS medium for somatic embryogenesis. The initial pH 5.7 of medium(full strength MS with 2.0mg/l BA and 0.1mg/l NAA) was good for embryo production. Potassium ion was taken up rapidly within 2 weeks. while $Ca^{++}$ and $Mg^{++}$ ion contents were almost constant during culture period. Sucrose hydrolysis occurred throughout the culture, while glucose and fructose were absorbed simultaneously from the third week of culture.

• 한국신재생에너지학회:학술대회논문집
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• 2010.11a
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• pp.163.2-163.2
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• 2010

We developed a simple method to synthesis a nitrogen doped graphene, nitrogen plasma treated graphene (NPG) sheets thought nitrogen plasma etching of graphene oxide (GO). X-ray photo electron spectroscopy (XPS) study of NPG sheets treated at various plasma conditions reveal that N-doping is classified to 3 kinds of binding configurations. The nitrogen doping concentration is at least 1.5 at % and up to 3 at% with changing of ratio of nitrogen configuration in NPG. Our group demonstrate ultracapacitor with high capacity and extremely durable using a NPG sheets that are comparable to pristine graphene supercapacitor, and pseudocapacitor using polymer and metal oxide with redox reaction, capacitance that are three-times higher, and a cycle life that are extremely stable. We also realized flexible capacitor by using the paper electrode that are coated by NPG sheets. NPG paper capacitor presented almost same performance compare with NPG on a metal substrate, and durability is much more enhanced than that. To additionally explain that how different kind of atoms in graphene layers can act as the ion absorption sites, we simulated the binding energy between nitrogen in graphene layer and ions in electrolyte. Increasing the energy density and long cycle life of ultracapacitor will enable them to compete with batteries and conventional capacitors in number of applications.

• Journal of Surface Science and Engineering
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• v.30 no.6
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• pp.391-399
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• 1997

To figure out wheher the tribological properties of a hras-coating layer can be imporved by ion implantatio, TiN-coated SKD 11 61 were implanted with nitrogen ion and their wear peoperties were examined systematically. The amount of nitrgen ione implanted on the coating layer was $2 \times 10^{15},\;10^{16},\;10^{17},\;and\;10^{18}\;ions/\textrm{cm}^2$, respectively. X-ray diffraction revealed theintensity of the peaks belong TiN tended to increase as the ion dose increased, which implied that the implantation promoted the formation of TiN in the coated later. Howeverthe hardensity of the specimens increased then decreased again as the ion dose increased, resulting in a obvious drop of the hardness for the ion does of $2 \times 10^{18}\;ions/\textrm{cm}^2$<\TEX>. While the adhesion of the coated layer of SKD 61 was excllent regrdless of the implatation, the adhesion of the later of SKD 11 was apparently improved by the implantation. The overall wear properties of SKD 11 was better than that of SKD 61, and the best result was yielded at the ion dose of $2 \times 10^{15}\;ions/\textrm{cm}^2$<\TEX>.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.4 no.1
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• pp.13-16
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• 2003

We implanted $N^+ion$ into TiO$_2$/Ti substrates with 70 keV by varying dose of 0, 2, 5, and $10{\times}10^{17}/cm$^2$$. In addition, $N^+ion$implanted TiO$_2$ specimens were annealed at $600^{\circ}C$ for 2 hours in Atmosphere. We investigated the color evolution, surface roughness, and hardness of specimens with doses. We report that the color changed from white into dark-yellow as dose increased. ion implanted surfaces became smooth when they were annealed. Moreover, hardness increased up to 10% when we annealed ion implanted TiO$_2$. Our results imply that we may enhanced titanium color and surface hardness.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2009.05a
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• pp.234-234
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• 2009

고밀도 플라즈마 질화를 위해 장비 내에 보조 HCD (Hollow Cathode Discharge) 전극을 설치하여 고밀도의 플라즈마가 발휘되도록 장비를 구축하였다. 기존 bias 플라즈마 질화는 1-10Torr의 공정압력인데 반하여 $10^{-1}-10^{-2}$Torr의 비교적 고 진동에서 고밀도의 플라즈마를 발생시켰다. HCD 질화는 bias plasma 질화 공정의 플라즈마를 비교하면 가스 비의 영향이 매우 큰 것드로 관찰되었으며 기존에 발표된 플라즈마 질화 관련 모델과 비교하여 관찰된 플라즈마 내에서는 ion species가 실제 공정에서도 영향을 미치는 것을 알 수 있었다.

• Journal of Ecology and Environment
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• v.34 no.3
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• pp.279-286
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• 2011

The effect of allelochemicals on growth, root nodule nitrogen fixation activity, and ion patterns of soybeans were investigated. We prepared 50 g/L (T50), 100 g/L (T100), and 200 g/L (T200) extract concentrations by soaking fresh red pine needles in a nutrient solution. Adding needles to the nutrient solution increased the content of total phenolic acids, osmolality, and total ions. The total phenolic content in the T50, T100, and T200 extracts were $206{\pm}12.61$, $335{\pm}24.16$, and $603{\pm}12.30$ mg gallic acid equivalents, respectively. The $K^+$, $Mg^{2+}$, $Ca^{2+}$, and $PO_4^{3-}$ content increased by adding needles to the nutrient solutions, whereas $SO_4^{2-}$ content decreased. The growth inhibition of soybeans was proportional to the needle extract concentrations, and the T100 and T200 concentrations resulted in remarkable growth inhibition. On day 20 after treatment, dry weight and nitrogen fixation activity of the root nodules were reduced by the T100 and T200 treatments, whereas the T50 treatment was not difference from the control. After day 10, total ion content in all treatment groups was not different in comparison with the control. However, total ionic content in all treatment groups decreased significantly compared with that in the control after day 20. The lowest total ion value was found for the T200 concentration. The T200 treatment also resulted in significantly reduced $SO_4^{2-}$ content. The amounts of $Mg^{2+}$, $Ca^{2+}$, and $Mn^{2+}$ were higher than those of the control for the T50 treatment on day 10 and for T100 on day 20 after treatment. A significant increase in osmolality was observed in the T200 treatment on day 10 and in the T100 treatment on day 20. These results suggest that under severe allelochemical stress conditions, a remarkable reduction in nodule formation, nitrogen fixation activity, and ion uptake eventually resulted in a decrease in leaf production. Furthermore, increased $K^+$, $Mg^{2+}$, $Ca^{2+}$, $Mn^{2+}$, and osmolality in soybeans exposed to lower concentrations of allelochemicals than the critical stress level helped overcome the stress.