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연속 주조 공정에서 평균 토크전류 추종에 의한 인발력 분배 제어
천창근,김철우,Chun, Chang-Keun,Kim, Cheul-U 한국조명전기설비학회 2004 조명·전기설비학회논문지 Vol.18 No.3
연속 주조 공정에서 설정한 속도로 주편을 인발하는 스트랜드 구동롤에 인발력이 적절하게 분배가 되지 않으면 주형 레벨의 주기적인 변동을 유발시킴과 동시에 주편의 품질을 저하하게 된다. 따라서 본 논문에서는 주편의 속도를 제어함과 동시에 각 구동롤에 운전자가 원하는 비율로 인발력을 분배할 수 있는 알고리즘을 제안한다. 제안된 방법은 전동기에 작용하는 토크 전류를 상위 제어기로 귀환하여 평균 토크 전류를 산출하고 각 구동롤 전동기의 토크 전류와 비교하여 전동기의 속도 기준값을 미소하게 변경함으로써 각 구동롤 전동기의 토크 전류가 평균 토크 전류에 추종하도록 하여 인발력을 분배한다. 그리고 과도상태 개선을 위하여 안티와인더업(anti-wind up) 제어기를 가진 인발력 제어기를 적용하였으며, 제안된 알고리즘의 확인을 위하여 포스코의 시험연주기에 적용하여 우수성을 입증하였다. If the withdrawal force of strand driven roll which is controlled with predetermined speed isn't distributed regularly in continuous casting process, mold level is changed cyclically and slab quality is not good. In this paper, both casting speed control and load sharing control algorithm of strand driven roll according to ratio which is set up by operator at same time is proposed. The proposed algorithm is to share the withdrawal force by following torque current of each driven roll as average torque current by changing speed reference of each driven roll motor. The load sharing control with anti-wind up for improvement transient state is adopted and the proposed algorithm is implemented in POSCO pilot caster.
천창근,김성욱,김흥주,장웅성,노중석,Chun, Chang-Keun,Kim, Sung-Wook,Kim, Heung-Joo,Chang, Woong-Seong,Noh, Joong-Suk 대한용접접합학회 2013 대한용접·접합학회지 Vol.31 No.2
Titanium and its alloys have been widely using in the various field of industry application due to high corrosion resistant properties and mechanical properties. Titanium is highly reactive in the high temperature state and the formation of titanium oxide and porosities in the nuggets of fusion welding will results in the degradation of the mechanical properties. For this reason the studies of friction stir welding for titanium have been investigated recently. The FSW zones of titanium were classified by the weld nugget (WN), the linear transition boundary (TB) and the heat affected zone (HAZ). The WN along with titanium parent was characterized by the presence of twins and dislocations. The average grain size and hardness of WN has been changed according to heat input. The grain refinement resulted from the FSW increased the hardness in the stir zone. Sound dissimilar joints between SUS 304 and CP-Ti were achieved using an advancing speed of 50 mm/min and rotation speeds in the range of 700-1100 rpm. Aluminum 1060 and titanium alloy Ti-6Al-4V plates were lap joined by friction stir welding, hence the ultimate tensile shear strength of joint reached 100% of Al 1060. Mg alloy and Ti were successfully butt joined by inserting a probe into the Mg alloy plate with slightly offsetting. But Ti-Al intermetallic compound layers formed at the interface of these joints.
천창근,장웅성,노중석,정태휘,조중선,Chun, Chang-Keun,Chang, Woong-Seong,Noh, Joong-Suk,Joung, Tae-Whee,Joh, Joong-Seon 대한용접접합학회 2006 대한용접·접합학회지 Vol.24 No.1
This paper describes the friction surface modification which has been successfully developed with the friction stir welding recently There are several problems including just position control and backlash in conventional friction surface modification system. Therefore it has been developed the friction surface modification system which has been controlled precisely both position and force by driving hydraulic cylinder in this paper. The mechtrode rotation speed(N) and feeding speed(Vz), travel speed(Vx,y) are of critical importance for the width and thickness of the coating in friction surfacing process. But there is no theoretical method of determining interrelations between process parameters affect the coating width and thickness. As a result of DOE(design of experiment) with developed system, the coating thickness and width seemed to decrease according to increase the mechtrode rotation speed(N) and traveling speed(Vx,y), to decrease feeding speed(Vz) apparently. However as the result of regression analysis the main effect was only the mechtrode rotation speed in the coating thickness.
마찰교반용접에서 툴의 형상이 접합부 강도에 미치는 영향에 관한 연구
천창근(Chang-Keun Chun),김흥주(Hyeng-Ju Kim),박인규(In-Gyu Park),전시현,장웅성(Woong-Seong Chang),Kyung-Su Umm 한국철도학회 2009 한국철도학회 학술발표대회논문집 Vol.2009 No.5월
As demand regarding a recent energy-saving rises, the using ratio of the aluminum plate in manufacturing of a railroad vehicle has been increasing. The aluminum structure to be applied to a railroad vehicle is divided to single skin and double skin, and the main aluminum product is mainly Al 6005 extrude and Al 5083 rolled in domestic market. The Al 6005 alloy is applied heat treatment in order to improve the strength of material. Therefore there is the disadvantage that the strength of welding zone decreases compare with base material's if you apply to fusion welding like MIG(metal inert gas) welding. In this paper we tried to apply friction stir welding to solve these problems. In this study we investigated how tensile strength and fatigue strength were changed in case of changing the shoulder diameter of thread tool.
연속주조기에서 Driven Roll Motor의 Load Sharing 제어
천창근(Chun Chang Keun),신건(Shin Geon),김철우(Kim Cheul U) 전력전자학회 2002 전력전자학술대회 논문집 Vol.- No.-
As the modern technology of continuous casting plant is focused on Improvement of slab quality, the control system of strand driven roll which has positive effect is investigated in this paper<br/> An irregular distribution of withdrawal force gives rise to horizontal crack in high and middle grade carbon steel. Based on the basic understanding on design concept of high technology company, monitoring the withdrawal force distribution of strand driven roll and analysis of the control system was performed at continuous casters of POSCO The control algorithm of withdrawal force distribution for AC motor vector control, which was derived from above study and had been applied for POSCO Kwangyang 1-4 continuous casting plant, is presented,
레이저 적층제조로 제작한 Ti-6Al-4V 합금의 열처리 전후 조직 및 기계적 특성에 관한 연구
천창근(Chang-keun Chun),김성욱(Sung-wook Kim) 대한용접·접합학회 2018 대한용접·접합학회지 Vol.36 No.5
RThe present work investigates the microstructure and mechanical properties of Ti-6Al-4V fabricated using directed energy deposition(DED) additive manufacturing process. Specially, the mechanical properties and microstructures of the Ti-6Al-4V plate with post-process heat treatment were studied. Rectangular parts were built in the Argon gas shielding box with condition laser power 280W, 310W, 340W. The as-built plates were heated to 954℃ below b-transus and then furnace cooled after holing for 2hours. The yield and ultimate tensile strength values for the building layer as-built plate in laser power 280W of 1,105±21 and 1,224 ± 10MPa respectively are different from values obtained from the building layer with post-process heat treatment of 789 ± 5 and 886 ± 9 MPa. There is also a significant difference in the elongation between as-built plate and post-process heat treatment plate with an engineering strain to failure of 3.5± 0.7% and 12.1± 1.1% in the plate. The microstructure in post-process heat treatment plate consists mostly of widmanstätten structure, whereas the as-built plate consists of martensitic structure in the columnar prior-β grain.
알루미늄 압출재의 접합부 강도에 영향을 미치는 마찰교반 점용접 툴 형상에 관한 연구
천창근(Chang-Keun Chun),박인규(In-Gyu Park),엄경수(Kyung-Su Umm),장웅성(Woong-Seong Chang) 한국철도학회 2009 한국철도학회 세미나자료 Vol.2009 No.5
Aluminum extrude is increasing to vehicle body manufacture of a recent railroad vehicle. Conventional welding of this aluminum extrude has been used MIG welding or resistance spot welding mainly. But the advanced manufactures like Japan's tried to apply the friction stir welding and friction spot joining at railroad vehicle body manufacture process. Therefore in this paper we tried to study to apply friction stir welding to AL 6005-T6 extrude which has been manufactured the railroad vehicle mainly. In this study we investigated first the mechanisms to affect the welding strength in friction stir welding. After we made the 3 tools of different shape, we observed how the welding strength changed while changing the welding time and the rotation speed, the plunging depth.