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구진(灸津)(Moxi tar)이 뇌신경세포(腦神經細胞)에서 Nitric Oxide의 생성(生成)에 관하여 미치는 영향(影響)
안영남 ( Young Nam Ahn ),안성훈 ( Seong Hun An ),양기중 ( Kee Zung Yang ),김풍식 ( Pung Sik Kim ),김광수 ( Kwang Soo Kim ),김종성 ( Jong Sung Kim ),도진우 ( Jin Woo Do ),김경식 ( Kyeong Sik Kim ),손인철 ( In Chul Sohn ) 대한경락경혈학회 2000 Korean Journal of Acupuncture Vol.17 No.2
This study was produced to examine the effects of moxibustion that had been played role to traditional oriental medical treatment on disease. Before this article, we reported that Moxi tar decreased Nitric Oxide(NO) in activated RAW 264.7 cell by LPS and INF-gamma, which was decreasing Nitric Oxide Synthase(J. Kor. AM-Meridian & Pointology Soc. Vol.17, No.1, pp.33-46, 2000). And this article we used 12-O-Tetradecanoyphorbol-13-aceate(PMA) and LPS in C6-glioma cell line to produce Nitric Oxide(NO). And results was that Moxi-tar decreased NO in activated C6-glioma cell by LPS and PMA significantly. So we proposed that Moxi-tar had anti-inflammation and anti-cytotoxity in C6-glioma cell by decreasing Nitric Oxide.
안영남,김철희,이원범,김정한,Ahn, Young-Nam,Kim, Cheolhee,Lee, Wonbeom,Kim, Jeonhan 대한용접접합학회 2013 대한용접·접합학회지 Vol.31 No.6
Gas nitriding is a surface hardening process where nitrogen is introduced into the surface of a ferrous alloy. During fusion welding of nitrided carbon steel, the nitride inside weld metal is dissolved and generates nitrogen gas, which causes porosities - blow holes and pits. In this study, several laser welding processes such as weaving welding, two-pass welding, dual beam welding and laser-arc hybrid welding were investigated to elongate the weld pool to enhance nitrogen gas evacuation. The surface pits were successfully eliminated with elongated weld pool. However blowholes inside the weld metal were effective reduced but not fully disappeared.
안영남,김철희,Ahn, Young-Nam,Kim, Cheolhee 대한용접접합학회 2013 대한용접·접합학회지 Vol.31 No.4
In this research, laser cladding characteristics were investigated for various filler metal feeding methods such as powder, cold wire, and hot wire feeding. Appropriate parameter window, deposition rate, material efficiency and dilution for each filler feeding method were evaluated with same laser power and cladding speed range. Laser powder cladding has wider process parameter window but higher material efficiency and lower dilution were achieved by laser wire cladding. Among these feeding methods, laser hot-wire cladding showed best efficiency in material usage and deposition rate.
내면 용접부재의 전자세 레이저-아크 하이브리드 용접 연구
안영남,김철희,김정한,Ahn, Young-Nam,Kim, Cheolhee,Kim, Jeonghan 대한용접접합학회 2015 대한용접·접합학회지 Vol.33 No.1
Laser-arc hybrid welding has been considered as an effective pipe girth welding process since early 2000's. Tolerance for fit-up offsets such as gap and edge misalignment is one of most important requirements in pipe girth laser-arc hybrid welding, and several approaches using parameter optimization, a laser beam scanning and an arc oscillation have been tried. However the required offset tolerance has not been fully accomplished up to now and laser-arc hybrid welding has not been widely applied in pipeline construction than expected, despite of its high welding speed and deep penetration. In this study, internal welding was adopted to ensure the offset tolerance and sound back bead. The effect of welding parameters on bead shape was investigated at the flat position. Also tolerances for gap and edge misalignment were verified as 0.5 mm and 2.0 mm, respectively. The position welding trials were conducted at several welding positions from the flat to the overhead position in a downward direction. With the fixed welding speed, arc current for gas metal arc welding current and laser output power, adequate welding voltages for gas metal arc welding were suggested for each position.
안영남(Young-Nam Ahn),김철희(Cheolhee Kim) 대한용접·접합학회 2015 대한용접·접합학회지 Vol.33 No.4
Laser-gas metal arc hybrid welding has been considered as an alternative process of gas metal arc welding for offshore pipe laying. Fiber delivered high power lasers which enable deep penetration welding were recently developed but high power welding characteristics were not fully understood yet. In this study, the influence of shielding gas composition on welding phenomena in high power laser welding was investigated. Bead shapes, melt ejection and dropping were observed after autogenous laser welding with 100% Ar, Ar-20% CO₂, Ar-50% CO₂, and 100% CO₂ shielding gas. Process parameter window was widest with Ar-50% CO₂ shielding gas and the penetration was deepest with 100% CO₂ shielding gas. The melt dropping was not observed when Ar-50% CO₂ or 100% CO₂ shielding gas was supplied.
GTA-GMA 하이브리드공정에 따른 자동차용 아연도금강판의 용접부 기공감소 (II)
안영남(Young-Nam Ahn),김철희(Cheolhee Kim) 대한용접·접합학회 2016 대한용접·접합학회지 Vol.34 No.4
The use of Zn coated steel has increased in the automotive industry due to its excellent corrosion resistance. Conventionally the BIW(body-in-white) structure and the hang-on parts have been made of Zn coated steel and more recently Zn coated steel began to be applied in the chassis parts. During gas metal arc (GMA) welding of the chassis part, lap fillet joint used to be adopted but spatter generation and porosities are most important concerns. In the industrial applications, an intentional joint gap was made to avoid the weld defects but it is not easy to control the size of joint gap. In this research, gas tungsten arc (GTA) is combined with GMA welding where GTA precedes GMA. As pulsed arc was adopted as GMA, GTA was oscillated along the longitudinal direction by pulsing GMA, but the arc oscillation did not disturb the molten droplet transfer of GMA welding. By increasing the distance between GTA and GMA, the length of weld pool increased and porosity could be reduced. Moreover porosity in the welds was fully removed when the distance between two arcs was 15 mm.
아연도금강판 겹치기 용접부에 대한 2패스 레이저용접 적용성 연구
안영남(Young-Nam Ahn),강민정(Minjung Kang),김철희(Cheolhee Kim) 대한용접·접합학회 2016 대한용접·접합학회지 Vol.34 No.4
During laser overlap welding of galvanized steel sheets, explosion of weld pool by the high pressure zinc vapor induces weld defects like porosity and blowhole. In this study, laser 2-pass welding was implemented to prevent the weld defects. Through the 1st pass welding, zinc layers on the faying surfaces were removed when proper heat input was applied. Excessive heat input could result in explosion even during the 1st pass welding and insufficient heat input could not remove enough region of zinc layer for the 2nd pass welding. Coating weights of 45 g/㎡ and 60 g/㎡ were considered and for both cases sound welds without weld defects could be achieved. In spite of 2-pass welding, softening of weld and heat affected zone was not observed and Zn coating was not diluted into the weld metal.