http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
양영도(Young-Do Yang),김영운(Young-Wun Kim),정근우(Keun-Wo Chung),김성보(Seong-Bo Kim),임대재(Dae-Jae Yim),김영직(Young-Gik Kim) 한국트라이볼로지학회 2007 한국트라이볼로지학회 학술대회 Vol.2007 No.6
New pour point depressants were prepared by making use of the random copolymerization of acrylate monomer. The pour point and cloud point of the synthetic polymers in diesel mixtures containing 5%(BD5) and 20%(BD20) biodiesel were investigated. The characteristics of the synthetic polymers which were random structure of P(St/SMA). P(SMA/St), P(SMA/OMA/St), P(LM/AMA/St), P(LMA/SMA/St) were analyzed by ¹H-NMR and GPC. When the synthetic polymers were added to BD5 and BD20 at the concentration of 5000ppm. The pour point of the terpolymers were -5℃~-10℃ lower than that of the copolymers. In the case of BD5 whose pour point is -12.5℃, the pour point of the existing additives and the P(LMA/SMA/St) polymer additive which showed the lowest pour point among the synthetic polymers were -37.5℃ and -35℃ respectively at the concentration of 5000ppm. The result showed the pour point of the P(LMA/SMA/St) polymer was higher than the existing additives. On the other hand. in the case of BD20 whose pour point is -10℃, the pour points of the existing additives and the P(LMA/OMA/St) polymer was -32.5℃ and -35℃ respectively at the concentration of 5000ppm. It showed that the P(LMA/OMA/St) polymer was lower than the existing additives. In the results of cloud point, the cloud point of the synthetic polymers revealed -3℃ lower than before addition of the polymers and -2℃ lower than the cloud point of existing additives.
자동차 차체용 TRIP강판의 저항 점용접부 Partial Interfacial Fracture 특성에 관한 연구
최철영 ( Chul Young Choi ),김인배 ( In Bae Kim ),김양도 ( Yang Do Kim ),박영도 ( Yeong Do Park ) 대한금속재료학회 ( 구 대한금속학회 ) 2012 대한금속·재료학회지 Vol.50 No.2
Resistance spot welding of TRIP780 steels was investigated to enhance understanding of weld fracture mode after tensile shear testing (TST) and L-shape tensile testing (LTT). The main failure mode for spot welds of TRIP780 steels was partial interfacial fracture (PIF). Although PIF does not satisfy the minimum button diameter (4√t) for acceptable welds, it shows enough load carrying capacity of resistance spot welds for advanced high strength steels. In the analysis of displacement controlled L-shape tensile test results, cracks initiated at the notch of the faying surface and propagated through the interface of weldments, and finally, cracks change path into the sheet thickness direction. Use of the ductility ratio and CE analysis suggested that the occurrence of PIF is closely related to high hardness and brittle welds, which are caused by fast cooling rates and high chemical compositions of TRIP steels. Analysis of the hold time and weld time in a welding schedule demonstrated that careful control of the cooling rate and the size of a weld nugget and the HAZ zone can reduce the occurrence of PIF, which leads to sound welds with button fractures (BFs).
고강도 강판 저항 점용접부 강도 및 파단에 미치는 Paint Baking의 영향
최철영 ( Chul Young Choi ),이동윤 ( Dong Yun Lee ),김인배 ( In Bae Kim ),김양도 ( Yang Do Kim ),박영도 ( Yeong Do Park ) 대한금속재료학회(구 대한금속학회) 2011 대한금속·재료학회지 Vol.49 No.12
Conventional fracture tests of resistance spot welds have been performed without consideration of the paint baking process in the automobile manufacturing line. The aim of this paper is to investigate the effect of the paint baking process on load carrying capacity and fracture mode for resistance spot welded 590 dual phase (DP), 780DP, 980DP, 590 transformation in duced plasticity (TRIP), 780TRIP and 1180 complex phase (CP) steels. With paint baking after resistance spot welding, the l-shape tensile test (LTT) and nano-indentation test were conducted on the as-welded and paint baked samples. Paint baking increased the load-carrying capacity of the resistance spot welded samples and improved the fracture appearance from partial interfacial fracture (PIF) to button fracture (BF). Improvement in fracture appearance after LTT is observed on weldments of 780 MPa grade TRIP steels, especially in the low welding current range with paint baking conditions. The higher carbon contents (or carbon equivalent) are attributed to the low weldability of the resistance spot welding of high strength steels. Improvement of the fracture mode and load carrying ability has been achieved with ferrite hardening and carbide formation during the paint baking process. The average nano-indentation hardness profile for each weld zone shows hardening of the base metal and softening of the heat affected zone (HAZ) and the weld metal, which proves that microstructural changes occur during low temperature heat treatment.
윤정봉 ( Jeong Bong Yoon ),조항식 ( Hang Sik Cho ),박영도 ( Yeong Do Park ),김양도 ( Yang Do Kim ),김영석 ( Young Seok Kim ),오원태 ( Weon Tae Oh ),남대근 대한금속·재료학회 2010 대한금속·재료학회지 Vol.48 No.3
The interfacial adhesion properties of enamel-coated, alloyed steels were in detail characterized by spectroscopic techniques. The surfaces of alloyed steels existed as oxidized states of Fe3O4. Therefore, the oxidized surfaces of the steels significantly interacted with the coated enamels for the adhesion. Ti-alloyed steel showed many micro-boundaries during thermal treatment and these micro-boundaries might cause the decline of the interfacial adhesion between enamel and steel. The depth profiles of enamel-coated, alloyed steels were investigated by GDS (glow discharge spectroscopy) and Ti component was found to be related to the interfacial adhesion between enamel and steel.