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백영남,김승조 慶熙大學校 材料科學技術硏究所 1998 材料科學技術硏究論集 Vol.11 No.-
The life of PVD coating bites is affected by the cutting conditions, such as feed rate, cutting depth and cutting velocity. The low carbon steel bars were cutted by a lathe with tool dynamometer. The cutting conditions were feed rates of 0.2∼0.3mm/rev., cutting depths 2∼3mm and cutting velocities between 500-700rpm. Data were analysed using both Taylor's tool life equation and modified Taylor's tool life equation.
백영남,장영권 대한용접접합학회 2000 대한용접·접합학회지 Vol.18 No.2
There are many weld defects such as surface crack, lack of fusion, and incomplete penetration (IP) in the butt joint weld of existing steel bridges. The crack-like defects may significantly reduce the fatigue life of the structure. This paper presents the procedure and the results of the fatigue life assessment of the butt joints with weld defects in the existing steel girder bridge. The butt joint welds with incomplete penetration were instrumented with strain gages to determine the stress histogram under normal traffic. Based on the measured stress histogram the crack propagation analysis were performed for the fatigue life assessment. By using the suggested procedure and methodology, one can decide the time of periodic inspection and the necessity of repair of the butt joint welds with serious weld defects in the existing steel bridge.
음극 아크 이온플레이팅법에 의한 박막상의 Microdroplets에 관한 연구
백영남,정창준 慶熙大學校 材料科學技術硏究所 1998 材料科學技術硏究論集 Vol.11 No.-
To measure the mechanical properties of titanium nitride films, on the silicon wafers, TiN films were coated by cathode arc ion plating(CAIP) method. The silicon wafers were selected for the calculation of the growing structure, microdroplets and roughnesses of titanium nitride films. The experimental variables were the substrate bias voltages, arc currents, distances between the target and substrate, and jig rpm. The morphologies of TiN films that surveyed by SEM. The creation of the microdroplet reduced with respect to the increase of the bias voltages, jig rpm and distances between the target and substrate, but the microdroplets were multiplied when the arc currents increased. The surface roughness of TiN films were under the influence of the droplets, and improved with increasing the bias voltages and distance between the target and substate, but the roughness became rough as the arc currents were increased.
교량의 피로강도를 고려한 맞대기용접부 불안전용입 한계결함 결정에 관한 연구
백영남,장영권 대한용접접합학회 2000 대한용접·접합학회지 Vol.18 No.3
The incomplete penetration(IP) discontinuity in butt joint weld, which is detected during safety analysis of the steel bridge by nondestructive evaluation(NDE) method, is classified as unacceptable defect according to the NDE codes and standards. In fact, there are a little allowance in butt joint weld in the view point of design criterion, and also detected IP discontinuity should be classified and evaluated for the fatigue strength and residual life estimation. In this study, we performed fatigue test to evaluate the fatigue strength of high strength steel(SWS490A) containing IP discontinuities in various size, the results compared and classified according to the bridge construction standard specification which published by korea administration of construction and traffic. Experimental results could be used to evaluate and estimate the IP discontinuities considering different stress range in butt joint bridge weld during periodic safety inspection.