• Journal of the Korean Institute of Telematics and Electronics
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• v.9 no.2
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• pp.1-16
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• 1972

In this paper, the characteristics of linearly tapered strip-line filters, where the even-mode and odd-mode characteristic impedances vary linearly with the same degree along the lines, are analyzed. The Impedance parameters of linearly tapered coupled strip-line, which is made by connecting two linearly tapered unsymmetric coupled strip-lines In cascade and the I:no input and output terminals are made equal, are obtained. Using the above parameters, the Image parameters of linearly tapered coupled strip-line filters are derived. The result of analysis shows that the line length can be made shorter and also the stop-band width between the fundamental and second pass-band becomes wider, compared with the coupled strip-line filters which use uniform strip-lines. Furthermore, the difference of impedance levels in the fundsmental and second pass-band becomes larger with the degree of taper of the lines. This property is unique, in comparison with the case of uniform or exponentially tapered strip-line filters.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.12
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• pp.127-132
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• 2004

It is very important to find out causes of strip pinching for the high quality of products and fer the stable operation of rolling system. We have examined the strip pinching from three points of view to find out the causes of strip pinching in rolling system: strip shape, rolling operation conditions, and behavior of strip. Wedge, off center, and difference of rolling force through CMD(Cross machine direction) are found to possibly provide major initial causes of strip pinching. Generally strip pinching occurred in the tail of strip. Thus, computer simulations by using a FEM code were also carried out to find out the initial mechanism of strip pinching depending upon the force and geometric boundary conditions at the time of strip tail rolling. The strong compression force effect due to the sudden release of strip tail from the work roll and non-uniform strip tail shape (ex. Fish tail) across the CMD were found to provide possible major causes of strip pinching.

• Transactions of Materials Processing
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• v.8 no.1
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• pp.78-91
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• 1999

The endless hot rolling has been focused as an innovative process technology for increasing the productivity drastically and reducing the imperfection of quality in hot rolled steel strip. To realize it in actual mill, a lots of new facilities such as bar coiler, movable LASER welder and high speed strip shear should be equipped. And also it is necessary to develop the control technique for changing the roll gap and rolling speed during rolling, which is named as Flying Gap and Speed Change control technology. To prevent a strip rupture caused by excessive tension, it is very important to minimize fluctuations in strip thickness and intension during FGSC control. In this paper, the mathematical model for FGSC control algorithm was suggested and dynamic simulation is performed to accertain the effect of suggested control method on fluctuations in strip thickness and tension. For endless hot rolling simulation, a lots of FGSC control situations, for instance - strip thickness change from strip to strip - strip width change from strip to strip - carbon content change from strip to strip are considered.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1999.08a
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• pp.423-428
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• 1999

A high precision hot strip width control method has been developed in this study by applying interstand looper tension measuring system at finishing mill stands. As with deviation of hot rolled steel strip is closely related to abnormal increase in the interstand strip tension, on-line measuring device of looped tension and data analyzing system was developed in this study. To determine dominant factors that will cause local width shortage, the logged data sets of bar width, bar thickness, looper tension, and strip thickness along the strip length were correlated with the data set of strip width change. With the result of the correlation analysis, existing sequence control logic and parameters for looper actuator were modified for strip width quality and the gains of the looper control were refined for the stable operation during the full passage of rolled strip. The on-line tension measurement and tension feedback control for looper system improved strip travelling stability and reduced strip width deviation in the srip top end region.

• Journal of the Korean Vacuum Society
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• v.17 no.6
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• pp.544-548
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• 2008

At the semiconductor industry, Photoresist(PR) strip progress has high cost and time consuming process. Accordingly, many research group have been focused on the shortening of the PR strip progress. But the replacements of newly developed materials rather than normally used strip have accompanied by cost consumption. Therefore, we suggested the Plasma Liquid-Vapor Activation (PLVA) method of general PR strip solution for saving the PR strip time and the high strip rate of PR residue. The PLVA method was very effective for PR strip progress. Also, the ion damaged PR(high dose implanted photoresist: HDI-PR) was almost impossible to strip. However, it was very difficult to characterize the change of chemical composition of HDI-PR between with and without PLVA method. Thus, physical properties of HDI-PR surface with and without PLVA method were measured by using the nano-indenter system.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1999.08a
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• pp.27-36
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• 1999

To have high flatness quality of hot rolled strip in the hot strip finishing mill train, a new inter-stand tension profile measuring device of segmented looper roll type(coined as Flatness Sensing Inter-stand Looper, FlatSIL) and a new flatness control system have been developed in this study. The device measures the strip tension profile across the strip width and informs the strip wave pattern to new flatness control system where work roll bending mode to relieve the strip wave is determined. The existing automatic shape control system which uses laser type shape-meter installed at the outlet of the last finishing mill stand strip tension between down coiler and last finishig mill since the latent wave concealed by the strip tension between down coiler and last finishing mill stand cannot be measured by the laser distance-meter. Thus the existing shape control system is not able to control the flatness through the full strip length. The new flatness control system, however, works for full strip length during strip rolling as far as the tension profile measuring device and work roll bender are on. With the new flatness control system, work roll bender is automatically controller to minimize the latent wave of the running strip and the flatness quality as well as strip travelling stability has been noticeably improved from strip head through body to tail.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.169-169
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• 2000

The modeling for the looper of a hot strip finishing mill to control the tension of the strip is presented. The looper is an arm pushing against the strip between stands in a tandem mill to keep the strip tension constant and to isolate the interactions of the adjacent stands. Tension is influenced by the difference in mass flow through the up stream and down-stream rolling stands. Tension is critical to strip quality, influencing width, gauge, and shape. This paper presents how looper angle and strip tension are controlled for a hot strip finishing mill.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.1091-1096
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• 2003

It is very important to find out causes of strip pinching for the high quality of products and for the stable operation of hot roiling system. We have examined the strip pinching from three points of view to find out the causes of strip pinching in hot rolling system: strip shape, rolling operation conditions, and behavior of strip. Wedge, off center, and difference of rolling force through CMD are found to possibly provide major initial causes of strip pinching. Generally strip pinching occurred in the tail of strip. Thus, computer simulations by using a FEM code were also carried out to find out the initial mechanism of strip pinching depending upon the force and geometric boundary conditions at the time of strip tail rolling. The strong compression force effect due to the sudden release of strip tail from the work roll and non-uniform strip tail shape (ex. Tongue tail) across the CMD were found to provide possible major causes of strip pinching.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.05a
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• pp.322-325
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• 2002

We describe the looper controller design for a hot strip mill. The looper is to control the strip tension which influences on the width of the strip. It is very important to control the looper control of the hot strip mill, but difficult to control the looper, because there exists on mutual interaction among strip gauge, looper angle, and strip tension. In this paper, we present the modeling for the hot strip finishing mill to control the tension of the strip and suggest a cross control method. The cross control is a very simple method that allows non-interacting control.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.242-242
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• 2008

반도체 공정에서 일정한 패턴을 만들기 위하여 Photoresist (PR)를 이용한 식각 공정을 사용하게 된다. 이러한 식각 공정은 반도체 직접도가 증가되면서 더욱 많은 단계의 공정을 요구하게 되었다. 그러나 식각 공정의 증가는 반도체 소자 생산을 위한 더 많은 시간과 비용을 요구하게 된다. 이를 해결하기 위하여 Photoresist를 사용하지 않은 공정으로 공정 단계를 간소화하기 위한 연구를 진행하고 있지만 아직 명확한 대한은 없다. 본 연구에서 는 PR의 strip 시간을 최대한 단축시키고 PR strip 잔여물의 빠른 제거를 위하여 기존 공정에서 사용 중인 strip 약 액을 플라즈마에 의하여 활성화하는 방법으로 PR strip 시간을 최대한 줄이는 방법에 대한 연구를 진행하였으며, 활성화된 strip용액이 더욱 빠른 strip율을 나타내는 것을 확인하였다. 또한 약액 활성화 방법으로 활성화된 strip 용액으로 PR을 일부 제거한 후 PR 표면의 물리적 특성 변화를 분석하여 약액 활성화된 strip 용액으로 인한 PR의 특성을 물리적 방법으로 접근하여 연구를 진행하였다.