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국정한,성호현,장복수,김남훈 한국기술교육대학교 2003 論文集 Vol.10 No.1
In this study, welding characteristic and mechanical properties of electro slag welding were systematically studied for SM490A and TMCP steel.In the electro slag welding which is widely used SM490A and TMCP steel materials are mainly used in a steel structures and complex building. As SM80G, ZO60 and SM70G are usually used welding wire. In this study, mechanical properties such as tensile strength, elongation and impact energy were measured for each welding conditions to determine the optimum processing conditions. In addition, hardness and microstructural analysis were conducted to characterize the welding properties. There results indicate that TMCP is suitable base material and SM80G, and ZO60 are the good welding electrodes for the electro slag welding.
용접입열량에 따른 CO₂용접부의 기계적 특성에 관한 연구
국정한,성호현 한국기술교육대학교 2001 論文集 Vol.8 No.1
ABSTRACT In this study, we investigate the welding characteristics, mechanical properties, stress intensity, fracture strength, and microstructure in the fusion zone of SS400 steels which were welded at four different heat inputs(10, 15, 20, and 25 KJ/cm) using either the flux cored wire (FCW) or solid wire (SW) in the CO2 welding system. Based on arc's stability, spatter, thinned-slag detachment, and bead apperance results, the mechanical properties of the FCW were much better than those of the SW. They decreased as heat increased. The increase of heat input and notch depth result in a decrease of the impact energy.
안정 크랙 성장에 있어서의 표준 Duplex강의 파괴거동
국정한 한국기술교육대학교 1994 論文集 Vol.1 No.1
In this study, the fracture behavior of standard duplex steel(UR45N) heat-treated at 1050℃ for 60min. and at 850℃ for 30min. was investigated. The fracture behavior of duplex steel using the SENB specimens was determined by J integral and CTOD tests. The results obtained in this study can be summarized as follows. 1. The Stretch Zone Widths(SZW, W=30mm) measured by scanning electron micrographs were 25㎛ (850℃) and 125㎛(1050℃), which were close to Ji values corresponding the crack incremental (da) in the onset of crack propagation. It was also discussed the possibility of the determining variable for the extent of brittle and ductile fracture by fractography. 2. Based on the J integral and CTOD test results, there was little change in the Jo.2 value with changing the specimen width in the onset of crack propagation. In cases where the test specimen heat-treated at 1050℃ for 60min. exhibited a lower width change than that at 850℃ for 30min. Since Ji, Jo.2 and CTOD values were useful fracture parameters in the elastic-plastic fracture, it was found that there was a proportional relationship between Ji and CTOD(di). 3. Specimens heat-treated at 1050℃ for 60min. showed a fibrous fracture surface, whereas specimens heat-treated at 850℃ for 30min. exhibited cleavage and fibrous fracture surface.
국정한(Kook, Jeong-Han),김기선(Kim Key-Sun) 한국산학기술학회 2011 한국산학기술학회논문지 Vol.12 No.11
본 연구는 상부에 설치되는 콘크리트 구조물 없이 설치되어 작동하는 새로운 소형 수문 시스템을 제안하였 다. 주요 메커니즘은 유압시스템, 수문 상하 이송 메커니즘, 수문 잠금 제어장치, 이물질이 감지되면 수문이 파손되 지 않도록 하는 안전장치 등으로 구성하였다. 유압 펌프 및 제어 시스템은 수문 시스템의 위치에서 떨어진 장소에 설치하여 상부 구조물을 제거할 수 있도록 하여 제어 하였다. 수문 인양 장치는 유압 액추에이터가 달린 래크와 피 니언이 측면에 설치되어 작동되며 그 결과 제품의 원가 절감, 작동시 안전성 확보 및 제품의 컴팩트화를 구현하였다. This study proposes the system of new small sluice gate operated without the upper concrete structure. The new mechanism is composed of hydraulic system, driving mechanism to feed the floodgate up and down, hydrological locking device, safety device and etc. The hydraulic pumps and control systems away from the location of the sluice gate systems are installed and controled in place. The feed device with the hydraulic rack, pinion and hydraulic actuator is installed on the side of the sluice gate. The following results take the advantages of cost reduction, operation safety and compact product.