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광폭 해가림시설의 차광자재에 따른 미기상과 4년생 인삼의 생육특성
안영남,이은섭,소호섭,한정아,조창휘 한국약용작물학회 2018 한국약용작물학술대회 발표집 Vol.2018 No.05
Background : This study researches on the microclimate, photosynthesis and growth characteristics for the development of shading materials proper for the wide and inclined ginseng cultivation facility which can respond to climate change and save labor. Methods and Results : The wide shading facilities were installed on the area of 1,000 ㎡ in 2014 and 4 facilities were installed on the test ginseng cultivation area. On Mar. 29, 2017, 2 blue shading nets [with the sun blocking rate of 85% (200 g/㎡) and 90% (220 g/㎡)] were installed each for 4 facilities. On June 26, 2017, the aluminum screen and black shading net (with the sun blocking rate of 40% each) were installed during the period of high temperature (30℃ or higher) for each facility. The maximum light intensity under the shading facility was high with blue shading net 85% and PE black shading net 40%, or blue shading net 85% and aluminum screen 40%, higher than other treatments. They were higher by 4.8 - 7.3%, 5.3 - 7.8% each in July and August. Among the coating materials for reducing the high temperature, the aluminum screen coating had less water leakage in early July, late July, mid-August and late August when the precipitation was more than 100 ㎜. The death of the aerial part of ginseng occurred less until October. The growth of the aerial part of 4-year ginseng was better in blue shading net 85% and PE black shading net 40%, blue shading net 85% and aluminum screen 40% or blue shading net 90% and PE black shading net 40% than in blue shading net 90% and aluminum screen 40% The photosynthesis rate was the highest in June with 3.67 μmol CO2/㎡/s under the blue shading net 90% and aluminum screen 40% and with 3.55 μmol CO2/㎡/s under blue shading net 85% and PE black shading net 40% for K-1. As for the land races ginseng, it was the highest with 3.55 μmol CO2/㎡/s under the blue shading net 85% and PE black shading net 40%. For the growth of the underground part of the 4-year ginseng, the blue shading net 85% + PE black shading net 40% or the blue shading net 85% + aluminum screen 40% was the best with respect to the growth of the ground part of the ginseng such as the length of root, the length of main root, diameter of root and weight of root than other treatment. Conclusion : Best coating materials for the wide shading facilities are the blue shading net 85% and aluminum screen 40%.
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,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.