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전기화학 임피던스 분석을 통한 자동차용 코일스프링 강의 부식 평가
이규혁 ( Kyu Hyuk Lee ),박중현 ( Jung-hyun Park ),안승호 ( Seung Ho Ahn ),서지원 ( Ji Won Seo ),장희진 ( Heejin Jang ) 한국부식방식학회(구 한국부식학회) 2017 Corrosion Science and Technology Vol.16 No.6
Coil spring steels from the automobile suspension part after field exposure for 10 years and those after anti-corrosion validation test in proving ground of 5,000 ~ 10,000 km were examined for corrosion damages. Partial loss of paint, accumulation of corrosion product, and cracking of paint and superficial material were observed. The surface and subsurface region of spring steels had compressive residual stress and high hardness by shot peening. The surface hardness values of the specimens were 620 ~ 670 Hv. They were 60 ~ 80 Hv higher than those of the samples taken from the middle part of the spring. The maximum compressive stress was -916 ~ -1208 MPa measured at depth of about 100 μm. Electrochemical impedance spectroscopy showed that the resistances of charge transfer and the paint layer of the spring steels ranged from several tens to millions Ωㆍcm<sup>2</sup>. The resistance of the field samples was much higher than that of the proving ground samples used in this study, implying that the proving ground test condition would be more corrosive than the field environment.
주조 방식 및 압연에 따른 연축전지용 납 합금 기판의 부식 특성
오꽃님 ( Kkochnim Oh ),이규혁 ( Kyu Hyuk Lee ),장희진 ( Heejin Jang ) 한국부식방식학회 2021 Corrosion Science and Technology Vol.20 No.5
In this study, we examined corrosion behaviors of two types of Pb alloys for a lead acid battery comparatively. One containing 6.6 wt% Sn, 36 mg/kg Bi, and 612.4 mg/kg Ca was prepared by twin-roll continuous casting. The other containing 5.2 wt% Sn, 30.5 mg/kg Ag, and 557 mg/kg Ca was made by twinbelt continuous casting. Potentiodynamic polarization tests were performed to evaluate corrosion resistance. Cyclic voltammetry was done to examine oxidation and reduction reactions occurring on the surface of each alloy in 4.8 M H<sub>2</sub>SO<sub>4</sub> solution. Electrochemical test results implied that the Pb alloy prepared with the twin-belt casting method was less stable than that cast with the twin-roll method. Such results might be due to precipitations formed during the casting process. Rolling did not appear to affect the corrosion behavior of the twin-roll samples with Ag < 10 mg/kg, while it reduced the anodic reaction of Ag on the surface of the twin-belt sample with 30.5 mg/kg Ag.
배치 및 인동 간격에 따른 아파트 건물의 자연통풍 적용에 관한 연구
조균형,유호천,이규혁 대한건축학회 1999 대한건축학회논문집 Vol.15 No.10
The purpose of this study is to propose the design criteria of apartment houses for the effective natural ventilation. To get the effective natural ventilation, we should consider the direction of the building, site planning patterns, and the distance between buildings Apartment houses are classified by the layout type, and the characteristics of air flow pattern and wind pressure are analyzed into chosen apartment houses To visualize the pattern of air flow, Fluid Mapping Table is used, and Wind Tunnel is used for wind pressure