• 한국분말재료학회지
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• 제10권1호
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• pp.15-20
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• 2003

Hybrid $A1_2O_3-TiC$ ceramic particle reinforced 6061 and 5083 Al composite powders were prepared by the combination of twin rolling and stone mill crushing process, followed by consolidating processes of cold compaction, degassing and hot extrusion. The composite bar consists of lamellar structure of ceramic particle rich area and matrix area, in which the hybrid was decomposed into each TiC of about $3-4\mutextrm{m}$ and $AI_2O_3$ particles of about $1-2\mutextrm{m}$ in diameter. It also found that fine $Mg_2Si$ precipitates of about 30 nm were embedded in the matrix, which have grains of about 3 $\mutextrm{m}$. Higher UTS was measured at the 5083 composite bar compared to the conventionally fabricated composite, due to again refinement effect by the rapid solidification. No particle was shown to form in the interface between the matrix and reinforcement, whereas carbon was diffused into the matrix.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1998년도 춘계학술대회논문집
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• pp.144-147
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• 1998

VCR is a back-up roll with a special contour which leads to the length of the contact line between back-up roll and work becones self adjustable in accordance with the width of the strip. The simulation of a finite element model and the on-line test at production mill demonstrate that the VCR roll may keep the crown of the roll gap relatively stable, and at same time, permit the rolling pressure to be adjusted over a wider range, and increase the effect of work roll bending on the roll gap. The VCR rolls have been successfully used at the first stands of two largest cold rolling mills in China, and on-line test has been done at a wide hot strip finishing train. The use of VCR roll has created favorable conditions for subsequent rolling passes and the achievement of better flatness quality.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2004년도 제5회 압연심포지엄 신 시장 개척을 위한 압연기술
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• pp.197-203
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• 2004

A full finite element (FE)-based approach is presented for the precision analysis of the strip profile in flat rolling. Basic FE models for the analysis of the mechanical behavior of the strip and of the rolls are described in detail. Also described is an iterative strategy for a rigorous treatment of the mechanical contact occurring at the roll-strip interface and at the roll-roll interface. Then, presented is an integrated FE process model for the coupled analysis of the mechanical behavior of the strip, work roll, and backup roll in four-high mill. A series of process simulation are conducted and the results are compared with the measurements made in hot and cold rolling experiments.

• 한국재료학회지
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• 제26권3호
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• pp.154-159
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• 2016

A roll-bonding process was applied to fabricate an AA1050/AZ91/AA1050 laminate complex sheet. Two AA1050 and one AZ91 magnesium sheets of 2 mm thickness, 30 mm width and 200 mm length were stacked up after surface treatment that included degreasing and wire brushing; material was then reduced to a thickness of 3 mm by one-pass cold rolling. The laminate sheet bonded by the rolling was further reduced to 2 mm in thickness by conventional rolling. The rolling was performed at 623K without lubricant using a 2-high mill with a roll diameter of 210 mm. The rolling speed was 15.9 m/min. The AA1050/AZ91/AA1050 laminate complex sheet fabricated by roll bonding was then annealed at 373~573K for 0.5h. The microstructure of the complex sheets was revealed by electron back scatter diffraction (EBSD) measurement; the mechanical properties were investigated by tensile testing and hardness testing. The strength of the complex sheet was found to increase by 11 % and the tensile elongation decreased by 7%, compared to those values of the starting material. In addition, the hardness of the AZ91 Mg region was slightly higher than those of the AA1050 regions. Both AA1050 and AZ91 showed a typical deformation structure in which the grains were elongated in the rolling direction; however, the mis-orientation distribution of grain boundaries varied greatly between the two materials.

• 공업화학
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• 제20권3호
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• pp.301-306
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• 2009

본 연구에서는 냉연도금공장의 각 단위공정에서 발생되는 폐수를 미생물을 이용하여 안정하게 처리하기 위하여 각 폐수의 특성파악과 처리조건을 도출하고자 하였다. 발생되는 폐수 중 알칼리성폐수가 전체폐수의 64%를 차지하였으며, 산중금속함유폐수는 30%를 차지했다. 탈류폐액의 COD는 53890 mg/L로 전체 폐수발생량의 0.03%에 불과함에도 불구하고 COD의 53%를 유발하고 있었으며, COD의 94%는 SCN에 의해 기인하였다. 혼합폐수를 미생물로 처리할 때 혼합폐수 중 SCN농도가 200 mg/L 이하일 때 제거가 용이하였다. 반면 COD 유발물질은 400 mg/L 이하가 되더라도 처리효율이 미흡하였다. 이는 탈류폐액 중에는 난분해성 유기물질이 다량 함유되어 있기 때문이라 판단된다. 혼합폐수를 처리할 때 초기에 pH가 7.33이었지만 8 h 후에는 7.99로 상승하였다. 이는 탈류폐액에 함유된 SCN이 박테리아에 의해 분해될 때 발생되는 암모니아에 의해 기인한 것으로 사료된다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.2230-2234
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• 2003

This paper proposes a distributed simulator for general control system in CEMTool. Systems can be described by SIMTool likes the simulink in Matlab. For distributed simulation, we can seperate any system into several parallel subsystems in SIMTool. The number of parallel subsystem can be determined by the system's property. After seperation, parallel simulator will do initialization, one-step-ahead simulation, block-distribution and ordering and so on. Finally, simulator will create independent C codes and executive files for each subsystem. The whole system is fulfilled by several PCs, and each PC executes one subsystem. There are communications among these subsystem using reflective memory or ethernet. We have made several experiments, and the 5-stand cold rolling mill control system is our main target. The result of parallel simulation has shown effective speedup in comparison with one pc simulation.

• 자원리싸이클링
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• 제11권5호
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• pp.24-29
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• 2002

철강압연공장에서 산세공정중 발생하는 산화철의 색상을 개선하기 위하여 배소로 조업과 색상혼합공정을 연구하였다. 배소로 조업에서는 조업온도, 폐산장입량, 폐산분사 노즐수에 대하여 검토하였으며, 색상혼합공정에서는 산화티탄, 실리카, 괴타이트를 색상혼합재로 검토하였다. 배소로 조업에서는 조업온도를 낮게 할수록 산화철의 명도가 개선되었으며, 색상혼합공정에서는 괴타이트 첨가 경우에 제일 많이 산화철의 적색 및 명도가 개선되었다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1995년도 추계학술대회 논문집
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• pp.350-354
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• 1995

The Tension Leveller of Cold Rolling Mill In POSCO performs levelling the strip in high speed line. But minor variations in operating condition of driving machines such as motor, gear box, and support bearings, a small gap-variation of supporter and strip slip by poor roll revolutions can cause serious problems in the quality of strip. In this study, firstly, A condition monitoring standard for each sensor is made through with the detail analysis of vibration and strip slip. Secondly, An automatic monitoring and diagnosing system was developed to monitor the condition of Tension Leveller, and diagnose the cause of abnormal condition. Finally, A diagnosing algorithm for abnormal condition and man-machine interface (MMI) for easy operation are developed.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2001년도 ICCAS
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• pp.179.6-179
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• 2001

This paper proposes the recognition method of the strip shape using the Least-Square method and the distinction method of the asymmetric shape and the compensation method upon the shape control values for the stainless steel cold rolling mill. This paper proposes the shape recognition method before control and the compensation method to minimize the fluctuation of the shape deviation and to get symmetric shape. This paper shows on line test results to verify the performance of the control method for the process. The experiments have been performed with respect to various material type, thickness, and strip width. The performance of the proposed method is obtained excellent quality and high productivity as results.

• 제어로봇시스템학회논문지
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• 제8권5호
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• pp.373-384
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• 2002

This paper presents a robust PID controller design technique using the concept of model matching method in the frequency domain. To design the robust PID controller satisfying disturbance attenuation and robust tracking property for a reference input, first an H$\infty$ controller satisfying given performance is designed using the H$\infty$ control method. And then, the parameters(proportional, integral, and derivative gains) of the robust PID controller are determined using the model matching at frequency domain. The proposed technique is applied to a position controller design of the web. The simulation results show that the proposed robust PID controller satisfies disturbance attenuation and tracking property.