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조선용 강재의 $CO_2$레이저 GMA 하이브리드 용접에서 갭 브리징 능력 향상기술 개발
채현병,김철희,김정한,이세헌,Chae, Hyun-Byung,Kim, Cheol-Hee,Kim, Jeong-Han,Rhee, Se-Hun 대한용접접합학회 2006 대한용접·접합학회지 Vol.24 No.5
For laser welding in shipbuilding industry, gap bridging capability is one of the most important characteristics to achieve the high productivity and good weld quality. Recently, laser-GMA hybrid welding process is regarded as a distinctive method to overcome the tight gap tolerance with improving the productivity. In this study, the influence of process parameters on the bead formation was experimentally analyzed and the relationship between the process parameters and geometric imperfections was investigated. It was revealed that undercut, excessive weld metal, excessive penetration and incompletely filled groove were the major geometric imperfections. The optimized wire feeding and arc pressure were necessary to ensure the gap bridging ability. The approach to select the process parameters was conducted for butt welding with up to 2mm joint gap, in which the sound weld beads were generated without changing the welding speed.
재생 WC 분산형 Fe계 하드페이싱 용접재료의 마모저항성에 미치는 Mn과 C 첨가의 영향
강남현,채현병,김준기,최종하,김정한,Kang, Nam-hyun,Chae, Hyun-byung,Kim, Jun-ki,Choi, Jong-ha,Kim, Jeong-han 한국재료학회 2003 한국재료학회지 Vol.13 No.12
The abrasion and impact wear resistance were investigated on the hardfacing weld dispersed with the recycled hard metal(HM). The HM was composed of the tungsten carbide(WC) reinforced metal matrix composite. The cored wire filled with the 25-35wt.% HM and 2-8wt.% of the alloying element, Fe-75Mn- 7C(FeMnC), was used for the gas metal arc(GMA) welding. By using the cored wire of the 25wt.% HM and FeMnC addition, the weld showed mostly constant wear loss for the abrasion as a function of the FeMnC content. This was due to the insufficient amount of the tungsten carbide formed during the GMA welding. The FeMnC addition to the 35wt.% HM did not improve the abrasion wear property since the amount of the tungsten carbide formed was decreased with respect to the FeMnC amount. The 6wt.% FeMnC addition to the 35wt.% HM exhibited the better impact wear resistance than the hardfacing weld by 40wt.% HM.
김철희,채현병,이창우,김정한,이세헌,Kim, Cheol-Hee,Chae, Hyun-Byung,Lee, Chang-Woo,Kim, Jeong-Han,Rhee, Se-Hun 대한용접접합학회 2006 대한용접·접합학회지 Vol.24 No.1
Laser-rotating arc hybrid welding was introduced by combining $CO_2$ laser and rotating gas metal arc welding. While the arc rotation enhances the weld pool motion, it reduces the undercut formation which is one of most critical weld defects in the conventional laser-arc hybrid welding. This research investigated the bead characteristics according to the welding parameters such as frequency of rotation, welding voltage, shielding gas composition and interspacing distance between laser and we. The welding parameters were selected to reduce spatter generation and ensure sound weld beads fur bead welding and butt welding with various joint gaps. Gap bridging ability was improved, such that the sound weld beads were achieved for butt joint with up to 2mm joint sap, with no adjustment of CTWD(Contact tip-to-workpiece distance) and electrode diameter.
재생 초경합금 분말을 활용한 금속기지 복합재료의 Abrasion 마모거동
강남현,채현병,김준기,최종하,김정한,Kang, Nam-Hyun,Chae, Hyun-Byung,Kim, Jun-Ki,Choi, Jong-Ha,Kim, Jeong-Han 한국재료학회 2003 한국재료학회지 Vol.13 No.12
The abrasion wear behavior on the hardfacing weld was investigated by performing abrasion wear, hardness, and microstructural tests. The gas metal arc(GMA) weld was produced by using the cored wire which was filled with the hard metal, i.e., the recycled tungsten carbide (WC) reinforced metal matrix composite. For 30% addition of the hard metal, the abrasion wear resistance was significantly improved comparing with that for 20% addition of the hard metal. Above 30% addition of the hard metal, however, there was no significant improvement of the wear resistance. The improvement of the wear resistance was due to the increased amount of eutectic carbides(W$_{6}$C) which was formed during GMA welding. For the weld in which the hard metal was added to 30-40%, an optimum level of abrasion wear resistance was performed.
아연도금 강판의 $CO_2$ 레이저-TIG 하이브리드 용접에 관한 연구 Part 2 : 공정변수와 용접성과의 관계
김철희,최웅용,채현병,김정한,이세헌,Kim, Cheol-Hee,Choi, Woong-Yong,Chae, Hyun-Byung,Kim, Jeong-Han,Rhee, Se-Hun 대한용접접합학회 2006 대한용접·접합학회지 Vol.24 No.4
Optimization of process parameters for laser-arc hybrid welding process is intrinsically sophisticated because the process has three kinds of parameters-arc, laser and hybrid welding parameters. In this paper, the relationship between weldability and several process parameters such as laser beam-arc distance, electrode height, welding current and welding speed, were investigated by the full factorial experimental design. Weld quality was evaluated by using weight of spatters which is related with the pore area. It was found that the weld quality was increased with the increases in laser beam-arc distance and welding current, and decreased with the increases in electrode height and welding speed.
아연도금 강판의 $CO_2$ 레이저-TIG 하이브리드 용접에 관한 연구 Part 1 : 용접현상분석
김철희,최웅용,채현병,김정한,이세헌,Kim, Cheol-Hee,Choi, Woong-Yong,Chae, Hyun-Byung,Kim, Jeong-Han,Rhee, Se-Hun 대한용접접합학회 2006 대한용접·접합학회지 Vol.24 No.4
In lap welding of zinc-coated steel, porosity formation is one of most significant weld defects, which is caused by zinc vapor generated between the steel sheets. Various solutions have been proposed in the past years but development of more effective method is a worthwhile subject to be investigated. In this study, autogenous laser welding and laser-TIG hybrid welding was applied to the lap welding of zinc-coated steel without gap, and weld pool behaviors were observed by using high speed camera and the porosity generation mechanism was analyzed. The weld defects were successfully eliminated by laser-TIG hybrid welding. This is because the leading TIG arc partially melted the upper sheet and vaporized/oxidized the coated zinc on the lapped surfaces prior to the trailing laser illuminating the specimen.
반도체 폐수처리 공정의 외부탄소원을 아세트산으로 대체 적용하기 위한 GPS-X 모의 연구
오승은 ( Seung-eun Oh ),채현병 ( Hyun-byung Chae ),추태호 ( Tai-ho Choo ),채수권 ( Soo-kwon Chae ) 한국환경기술학회 2016 한국환경기술학회지 Vol.17 No.3
고농도 질소가 함유된 반도체 폐수처리 공정에서 탈질 외부탄소원으로써 메탄올이 과량으로 사용되고 있다. 따라서, 메탄올은 화재 및 폭발 등과 같은 안전문제가 발생될 확률이 높아서 안전한 외부탄소원으로써 아세트산을 사용하기 위해서 반도체 폐수처리 공정을 GPS-X로 적용성 및 최적 운전조건을 모의하였다. 메탄올과 아세트산의 회분식 탈질실험으로 탈질속도를 비교한 결과, 탈질반응 1시간 후 탈질속도는 아세트산을 400 mg/L 주입한 경우 0.0027 mgNO<sub>3</sub>-N/hr/MLSS로 메탄올 400 mg/L를 주입한 경우보다 약 2배 빨랐다. 대체 외부탄소원으로써 아세트산을 사용한 GPS-X로 후탈질조의 C/N비, 체류시간, 내부반송률 및 슬러지반송률 변화에 따라 최적운전을 모의하였다. 모의한 결과, 후탈질조의 C/N비, 체류시간, 내부반송률, 슬러지반송률은 각각 4, 5hr, 300%, 50%이었다. 이 운전조건으로 고농도 질소를 함유한 반도체 폐수를 운전 모의한 결과, 후탈질조의 NO<sub>3</sub>-N 제거율과 탈질율은 각각 84.3%, 262 mgN/L/d였으며, 최종 방류수의 TN은 12.1 mg/L로 방류수질 기준을 만족하였다. Methanol is used in poisonous doses as external carbon source on the semiconductor wastewater treatment process that includes high concentration of nitrogen. We simulated application and optimum operation conditions on semiconductor wastewater treatment process to use acetic acid as safe external carbon source, using GPS-X because methanol is big possible that fire and explosion are caused. Batch denitrification experiment result dosing each methanol and acetic acid 400 mg/L was that the denitrification velocity of acetic acid, 0.0027 mgNO<sub>3</sub>-N/hr/MLSS, was nearly twice faster than the denitrification velocity of methanol. We simulated optimum operation conditions using GPS-X depending on C/N ratio and HRT (hr) of the post-denitrification tank, internal recycle rate (%), sludge recycle rate (%). As a result of simulation, optimum operation conditions were that C/N ratio and HRT of the post-denitrification tank, internal recycle rate, and sludge recycle rate were each 4, 5hr, 300%, and 50%. When the semiconductor wastewater treatment process was operated with optimum operation conditions, NO<sub>3</sub>-N removal efficiency and denitrification rate on the post-denitrification tank were each 84.3% and 262 mgN/L/d. Also final effluent TN concentration satisfied water criteria as 12.1 mg/L.
재난을 예방·대응하기 위한 사각 하수암거 원격 탐사 시스템 개발에 관한 연구
이동욱 ( Dong-wook Lee ),채현병 ( Hyun-byung Chae ),채수권 ( Soo-kwon Chae ) 한국환경기술학회 2017 한국환경기술학회지 Vol.18 No.2
오래된 하수관거와 같은 지하매설물들의 손상에 의해 하수가 누수됨으로서 싱크홀 같은 도로함몰사고가 급증하고 있다. 이와 같은 사고에 대응하고 예방하기 위하여 하수관거시설의 누수를 제어하고 감시하는 장치들이 개발될 필요가 있다. 그러므로 본 연구에서는 카메라, 계측기 등이 하수관의 윗부분에 설치된 레일을 따라서 이동함으로써 관거 내부를 전체적으로 조사가 가능하도록 하였다. 그리고 하수관거 상부에 설치된 레일에 의해 전·후진이 가능하고 기존기술보다 빠른 속도로 모니터링이 가능한 시스템을 개발하였다. 이와 같이 개발된 시스템에 의해 지하시설물의 환경 상태를 제어하고 감지할 수 있도록 시리얼 인터페이스를 갖는 내부 네트워크로 상호 연결한 효율적인 모듈 시스템의 설계방법에 대하여 제안하였다. 본 연구에서 제안된 방법은 급변하는 환경 및 재난 시장에서 요구되는 조건과 환경인자들의 사양에 대하여 보다 적응성 있고 유연한 설계 기법을 제공하리라 기대된다. Damage to underground facilities such as old sewer pipes has caused leakage of sewage, and road sink accidents like sinkholes are increasing rapidly. In order to correspond to safety accidents, it is necessary to develop devices for controlling and monitoring the leakage of sewerage facilities. Therefore, in this study, the camera, sensor, etc. are moved along the rail installed on the upper part of the sewer pipe, so that the entire investigation inside the pipe can be done. And it was possible to develop a system that can move forward and backward by rails installed at the upper part of the sewer pipe and monitor at a faster speed than existing technology. In order to control and detect the environmental condition of the underground facility by the developed system, this study proposed an efficient method of designing the module system interconnected with the internal network with the serial interface. It is expected that the proposed method in this paper is able to provide the more adaptable and flexible design technique for the specification of condition and factors needed in the fast-changed environment market.