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고영봉,최준웅,박경채,Ko, Young-Bong,Choi, Jun-Woong,Park, Kyeung-Chae 대한용접접합학회 2010 대한용접·접합학회지 Vol.28 No.1
In Friction Stir Lap Welding(FSLW), the movement of material within the weld was more important than the microstructure, due to the interface present between the sheets. Thus, The soundness of free defect, Effective Sheet Thickness(EST) and width of joint were most important factor of mechanical properties. Specimens by lap joint types that were 'A-type' and 'R-type' were made in this study. A-type tensile specimen was loaded at advancing side and R-type tensile specimen was loaded at retreating side. Macro-, micro-structural observation and mechanical properties of FSLW A5052-H112 alloy ware investigated under varying rotating and welding speed. The results were as follows: Material hook formed decreasing after sharply increasing was appeared at the end interface of joint area in advanced side, and material hook formed decreasing after smoothly increasing was observed at that in retreated side. Tensile load had no relation with defects. As rotating speed was higher, tensile strength was increasing and EST was decreasing regardless of joint types. joint efficiency was over 70%. In a result of fractography, fracture in A-type was partially occurred by dimple in SZ, and fracture in R-type was generally occurred by dimple in HAZ.
A5052-H112 합금의 겹치기 마찰교반접합 조직 특성
고영봉,이중헌,박경채,Ko, Young-Bong,Lee, Joong-Hun,Park, Kyeung-Chae 대한용접접합학회 2009 대한용접·접합학회지 Vol.27 No.6
The Friction Stir Welding(FSW) has mainly been used for making butt joints in Al alloys. Development of Friction Stir Lap Welding(FSLW) would expand the number of applications. Microstructure of FSLW in A5052-H112 alloy was investigated under varying rotation and welding speed. As the rotation speed was increased and the welding speed was decreased, a amount of heat was increased. As a result, bead interval was narrower, bead width are larger, and experimental bead interval was almost similar to theoretical bead interval. Typical microstructures of FSLW A5052-H112 alloy consist of three zones, including Stir Zone(SZ), Thermo-Mechanically Affected Zone(TMAZ) and Heat Affected Zone(HAZ). As a amount of heat was increased, average grain size was larger in three zones. Nevertheless, the aspect ratio was almost fixed for FSLW conditions. The misorientation of SZ, HAZ and TMAZ was examined. A large number of low angle grain boundaries, which were formed by severe plastic deformation, were showed in TMAZ as comparison with SZ and HAZ. Microhardness distribution was high in order of BM, SZ, TMAZ, and HAZ. The Micro-hardness distribution in HAZ, TMAZ of upper plate were lager than lower plate. Relationship between average grain size and microhardness was almost corresponded to Hall-Petch equation.
프루브 길이에 따른 A5052 겹치기 마찰교반접합 특성
고영봉(Young-Bong Ko),강채원(Chae-Won Kang),최준웅(Jun-Woong Choi),박경채(Kyeung-Chae Park) 한국표면공학회 2009 한국표면공학회지 Vol.42 No.6
The Friction Stir Welding (FSW) has mainly been used for making butt joints in Al alloys. The development of Friction Stir Lap Welding (FSLW) would expand the number of applications. In this study, for effective application on thin aluminum alloy lap joint, non-heat treatment A5052 alloys were joined by FSLW with the length of probe 2.3 ㎜ and 3.0 ㎜. Investigating the characteristics of joint area showed the results were as below ; When the length of probe was 2.3 ㎜, good joint area was formed at all welding condition except for 600 rpm-700 ㎜/min. In the case of 3.0 ㎜ probe length, there was formed good joint area without defects at 1500 rpm-100 ㎜/min. The width of joint area, position and size of defects were very important factors for FSLW, due to heat input and stirring intensity.
5052 알루미늄 합금에서 접합변수에 따른 겹치기 마찰교반접합부의 특성
고영봉(Young-Bong Ko),박경채(Kyeung-Chae Park) 한국표면공학회 2012 한국표면공학회지 Vol.45 No.5
The Friction Stir Welding (FSW) has mainly been used for making butt joints in Al alloys. The development of Friction Stir Lap Welding (FSLW) would expand the number of applications. In this study, microstructures and mechanical properties of FSLW in A5052 alloy were investigated under varying rotating speed and probe length. Investigating the characteristics as FSLWed conditions were as below ; Failure Maximum load by shear fracture was increased proportional to the width of joint area, which was increased by input heat, stirring intensity in the case of 2.3 mm probe length. Tensile fracture occurred, and maximum load was determined due to side worm hole of joint area and softening of microstructure in the case of 3.0 mm probe length. In the case of 3.7 mm probe length, material hook and bottom worm hole were appeared at the end interface of joint area. The most sound FSLW condition with no defects was 3.0 mm probe length and 1500 rpm-100 mm/min. No defects were showed in 1500 rpm-100 mm/min and 1800 rpm-100 mm/min, but Vickers microhardness distribution in TMAZ/HAZ which was fracture zone was lower in 1800 rpm-100 mm/min than in 1500 rpm-100 mm/min. In this condition highest tensile strength, 215 MPa (allowable rate 78% of joint efficient) was obtained.
고영봉 ( Young Bong Ko ),정형석 ( Hyoung Seok Jung ),백지훈 ( Ji Hoon Baek ),이한준 ( Han Jun Lee ),하용찬 ( Yong Chan Ha ) 대한고관절학회 2013 Hip and Pelvis Vol.25 No.2
소아에서 급성 화농성 고관절염의 치료는 반복적인 관절천자, 개방성 관절 절개술, 관절경적 배액술 등이 소개되고 있다. 그러나, 소아에서 발생한 화농성 고관절염의 관절경을 이용한 치료에 대한 보고는 드물다. 저자들은 3세 소아에서 고관절 급성 화농성 관절염에 대하여 견인장치 없이 도수견인 통해 30°, 2.7-mm 족근관절용 관절경을 이용하여 치료하였으며, 수술 후 2주에 완전한 고관절 운동범위을 회복하였고, 수술 후 2년 추시 상 재발 소견은 관찰되지 않았다. Recommended treatment options for acute septic arthritis in children include repeated aspiration, open arthrotomy, and arthroscopic drainage. However, reports of arthroscopic treatment of septic arthritis of the hip in a child are rare. We experienced a case of arthroscopic management of acute septic arthritis of the right hip joint in a three-year-old child using a 30°, 2.7 mm arthroscope for the ankle joint through manual traction without use of a traction table. The patient had complete range of motion in the right hip joint two weeks after surgery and recurrent infection was not observed at the final follow-up two years postoperatively.
C1020/Al6063 이종 합금의 맞대기 마찰교반접합의 접합특성
고영봉(Young-Bong Ko),최준웅(Jun-Woong Choi),조제형(Je-Hyoung Cho),김헌우(Hyen-Woo Kim),박경채(Park Kyeung Chae) 한국표면공학회 2009 한국표면공학회지 Vol.42 No.5
The Friction Stir Welding (FSW) has mainly been used for making butt joints in Al alloys. Development of FSW would expand the number of applications. The FSW is a relatively solid-state joining process. This study possibility of a welding between C1020 and Al6063 by means of FSW has fundamentally clarified. The primary process parameters, such as a rotating speed, rotating direction of tool and off-set of pin periphery from materials interface were optimize, respectively.