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모넬(Monel)-Clad 파이프의 오버레이 용접 적층수가 용접성에 미치는 영향에 관한 실험적 연구
최혁(Hyeok Choi),박준홍(Joon-Hong Park) 한국산학기술학회 2016 한국산학기술학회논문지 Vol.17 No.11
오버레이 용접은 희석율에 의해 적층 두께에 따라 화학성분 함량과 용접부의 경도에 영향을 미치며 이는 파이프 제품의 표면성질을 결정한다. 이로 인해 오버레이 용접은 적층의 수를 고려하여야 한다. 본 연구에서는 탄소강 모재에 내부식성 소재인 모넬 소재를 오버레이 용접하여 적층수에 따른 Fe함량, 모재와 모넬 소재와의 용접성, 부위별 경도와 표면 평탄도를 실험적으로 연구하였다. 각각의 평가는 평판의 모재와 파이프 모재에 3개의 층으로 오버레이 용접 후 실시하였다. Fe함량은 각 층별 시료를 채취하여 성분 분석을 통해 평가하였으며, 3Layer에서 만족하는 함량을 나타내었다. 또한 적층별 시편을 밴딩 시험하여 용접성을 평가하였다. 적층별 경도와 비드 평탄도는 Micro Vickers와 3차원 측정을 통해 평가하였다. 경도는 1Layer에서 발생하는 HAZ부에 의해 가장 높은 경도 값을 보였으며, 적층이 증가할수록 경도가 감소하였다. 비드 평탄도의 경우 적층수 증가에 따라 편차가 급격한 차이가 발생하였으며, 이는 경도와 함께 사용 목적의 측면에서 주의 깊게 고려해야 한다. 이러한 실험적 결과는 목적에 따른 용접 파이프 적층수의 결정 방법을 나타내었다. Overlay welding affects the chemical components and weld hardness by dilution of the lamination layer thickness, which determines the surface properties. This study experimentally investigates different numbers of layers for overlay welding monel materials, which are anti-corrosion materials. The Fe content, weldability of the base metal and monel materials, hardness, and surface flatness were examined. Each evaluation was carried out after overlay welding with three layers on the base material and pipe base material of the plate. The Fe content was evaluated by analyzing the constituents of each layer. The Fe content was satisfactory in the three layers. The weldability of the laminate specimens was evaluated by a bending test. The hardness and bead flatness of the laminate specimens were evaluated by micro Vickers and 3D measurements. The hardness was highest in the heat-affected zone with one layer, and it decreased with increasing lamination. In the case of bead flatness, there is a sharp difference in the deviation with increasing numbers of laminations, which should be considered carefully.
Pilot 규모의 정수처리용 정밀여과 시스템에서 PACs 응집제가 투과 플럭스에 미치는 영향
김지훈 ( Ji Hoon Kim ),최혁 ( Hyeok Choi ),김형수 ( Hyung Soo Kim ),염익태 ( Ick Tae Yeom ),한기봉 ( Gee Bong Han ) 한국물환경학회 2003 한국물환경학회지 Vol.19 No.2
This paper assesses the results obtained from a microfiltration(MF) pilot plant operation with surface water during two months. A pilot plant operated in cross flow filtration feed and bleed mode continuously(pore size 0.22㎛, tubular MF membrane). The most important operational parameter achieved during the pilot experiment was permeability. The permeability depends on characteristics of the raw water, membrane surface properties, and operation condition. If the coagulated water is supplied without coagulation process, conventional membrane separation devices have a risk of decreasing permeate flux due to plugging of flow path and fouling of the membrane surface. Consequently, in this experiment, the initial permeate flux decline about almost 50% is due primarily to the silicate deposition of PACs(polyaluminium chloride silicate) coagulant on the membrane surface. Also, the permeate flux is never restored again by irreversible deposition(attachment) of silicate particles on the membrane surface.
김지훈(Ji Hoon Kim),최혁(Hyeok Choi),김관엽(Kwan Yeop Kim),김형수(Hyung Soo Kim),김진모(Jin Mo Kim) 한국물환경학회 2002 한국물환경학회지 Vol.18 No.1
This study was focused on investigating ability to maintain long-term high flux, especially variation of flux according to concentration ratio in actual reservoir water purification system using membrane separation technology. The pilot plant was operated in dead-end-filtration mode. The membranes used were hollow fiber microfilter with nominal pore size 0.1㎛. The permeate flux was maintained 25LMH(ℓ/㎡ hr). Materials causing SS and turbidity were almost completely removed and removal percent of UV_(260) and DOC was 40%. Measured max. concentration of SS and turbidity about concentrated water during any one cycle corresponded with predicted max. concentration through simple mass balance, and each measured max. concentration of UV_(260) and DOC was 84%, 80% of predicted max. concentration.