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레이저 플라즈마 분광분석법을 이용한 표면처리 된 마그네슘 합금 표면의 경도 분석
강동찬(Dongchan Kang),김주한(Joohan Kim) 한국생산제조학회 2015 한국생산제조학회지 Vol.24 No.6
The hardness of surface treated magnesium alloy was evaluated using laser induced breakdown spectroscopy. The surface of the specimen was hardened mechanically, and the hardness profiles were measured using a traditional measurement technique. A laser beam was irradiated to generate a plasma, and the peaks of the components of the specimen were analyzed. A wavelength of 333.66 nm and 293.65 nm were selected as the atomic and ionic peaks, respectively. The ratios of the ionic peak to the atomic peak were obtained so as to compare the hardness profile. As the depth increased, the ratio decreased. These results are in good agreement with the previous hardness measurement results. It can be considered that this technique could be applied for remote and time-efficient hardness measurement.
레이저 유도 플라즈마 분광분석법을 적용한 금속표면의 부식 특성에 관한 연구
강동찬(Dongchan Kang),김주한(Joohan Kim) 한국기계가공학회 2017 한국기계가공학회지 Vol.16 No.1
The corrosion of metal specimens was analyzed in this study using laser-induced breakdown spectroscopy. The samples used in the study were magnesium alloys and corrosion, and standard specimens were prepared and analyzed using surface and depth analysis. The spectral wavelengths used in the oxide layer analysis were 777.196 nm, 777.421 nm, and 777.543 nm. The spectral line of the surface corrosion was confirmed by experimentation, and surface micro morphology analysis was performed using an optical microscope. Approximately 100 μm corrosion depth was confirmed via laser irradiation in the depth direction. The results of laser-induced breakdown spectroscopy and the SEM-EDS analysis were compared and analyzed.
내식성 향상을 위한 마그네슘합금의 ZrO<sub>2</sub> 적용 레이저 표면 처리
윤상우,강동찬,김주한,Yoon, Sangwoo,Kang, Dongchan,Kim, Joohan 한국기계가공학회 2016 한국기계가공학회지 Vol.15 No.4
The laser surface treatment of magnesium alloy was studied. $ZrO_2$ was used as sintering ceramics, and its corrosion resistance was verified. Appropriate laser parameters were proposed for homogeneous solidification of the sintered layer. The chemical compositions of the sintered layer were analyzed with laser-induced breakdown spectroscopy. $Na_2SO_4$ was used for a corrosion test, and the resistance of the sintered sample was confirmed. The microstructures of the sintered parts were also examined. The solidified grains on the top sintered surface were observed; however, reasonable fusion was obtained at the interface between the baseline and the ceramics. Laser surface treatment using $ZrO_2$ on magnesium alloy showed an improvement in corrosion resistance.
내식성 향상을 위한 마그네슘합금의 ZrO₂ 적용 레이저 표면처리
윤상우(Sangwoo Yoon),강동찬(Dongchan Kang),김주한(Joohan Kim) 한국기계가공학회 2016 한국기계가공학회지 Vol.15 No.4
The laser surface treatment of magnesium alloy was studied. ZrO₂ was used as sintering ceramics, and its corrosion resistance was verified. Appropriate laser parameters were proposed for homogeneous solidification of the sintered layer. The chemical compositions of the sintered layer were analyzed with laser-induced breakdown spectroscopy. Na₂SO₄ was used for a corrosion test, and the resistance of the sintered sample was confirmed. The microstructures of the sintered parts were also examined. The solidified grains on the top sintered surface were observed; however, reasonable fusion was obtained at the interface between the baseline and the ceramics. Laser surface treatment using ZrO₂ on magnesium alloy showed an improvement in corrosion resistance.
TFM Direct 모드 영상을 이용한 결함 기울기 및 깊이 측정 연구
안형근(Houng Kun Ann),강동찬(Dongchan Kang),김성민(Seong Min Kim),박익근(Ik keun Park) 한국비파괴검사학회 2022 한국비파괴검사학회지 Vol.42 No.1
위상배열초음파탐상검사(Phased Array Ultrasonic Testing;PAUT)의 새로운 기법인 FMC(Full Matrix Capture)/TFM(Total Focusing Method)기법은 후처리를 통해 결함에 따라 다양한 모드를 적용해 영상화가 가능하다는 장점을 가지고 있다. 하지만 결함의 기울기와 깊이에 따라 영상화 결과가 상이하여 조건 선정에 어려움이 있으며, 종파와 횡파의 속도 차이로 인해 무관련 지시가 나타나 건전부와 결함을 오인하는 문제가 발생한다. 따라서, 횡파 및 종파 웨지를 사용하여 TFM 다중모드 영상화 결과를 분석하여 결함의 기울기와 위치를 명확하게 검출할 수 있는 모드를 선별하고 무관련 지시의 신호 특성을 파악하는 연구가 필요하다. 본 연구에서는 결함의 기울기와 깊이가 TFM 영상에 미치는 영향을 파악하기 위해 탄소강에 70°부터 110°까지 10°간격의 기울기를 가지는, 1, 3, 5, 7, 9 mm의 다양한 깊이의 인공 결함을 방전 가공하여 제작하였다. 해당 시험편을 대상으로 횡파 및 종파 웨지를 이용한 TFM Direct 모드 적용 결과 실제 실험 결과와 시뮬레이션 결과를 비교 분석하였으며, 결함의 기울기에 따른 깊이 분석에 TFM Direct 모드의 유용성을 검증하였다. The full matrix capture (FMC) technique used in phased array ultrasonic testing (PAUT) collects all the transmitted and received information generated at the phased array transducer elements in the form of A-scan data without using the typical focal law. The total focusing method (TFM) is proposed here as a means to detect defects through a combination of various modes by post-processing and imaging the data acquired via FMC with improved clarity and resolution at the virtual region of interest (ROI), which is equivalent to PAUT. The combination of longitudinal and transverse modes allows the imaging of defects with varying slopes and depths, depending on the mode used. In this study, test samples with different defect slopes and lengths were prepared using longitudinal and transverse wave wedges, and the usability of the proposed method was verified by comparing the TFM direct mode test results and CIVA simulation results.