• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.293-293
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• 2012

마그네트론 스퍼터링으로 Al과 Al 합금(Al-3wt%Si, Al-10wt%Si) 박막을 코팅하였다. 기판은 냉연강판과 Si 웨이퍼를 사용하였으며 알코올과 아세톤으로 초음파 세척 후 진공용기에서 플라즈마 청정을 실서히였다. 시편 청정이 끝나면 기판은 0, 30, 45, 60, 90도의 다양한 각도로 고정시켜 Al과 Al 합금 박막을 코팅하였다. 빗각 증착 기술(Oblique Angle Deposition: OAD)은 입사증기가 기판과 수직하지 않게 기울여 코팅하는 방법으로 조직을 다양하게 제어할 수 있다. 빗각으로 코팅한 순수한 Al 박막의 경우, 동일한 두께의 박막보다 반사율 및 표면조도, 내식성이 향상되는 결과를 얻었다. 따라서 본 연구에서는 빗각 및 Si 함유량이 반사율 및 표면조도, 내식성에 미치는 영향을 비교 분석하였다. 기판의 위치에 따른 변화를 관찰하기 위해 시편은 좌, 우, 중간으로 구분하여 분석하였다. 단일층 박막의 경우 타겟과의 거리에 따른 두께 편차가 발생하였으며 이러한 두께 편차를 해결하기 위한 방법으로 동일한 각도를 유지하며 반대 방향으로 회전시켜 다층구조로 박막을 제조하였다. Si 함유량 및 빗각에 따른 반사율 및 표면조도를 분석하였으며 내식성 평가를 위한 염수 분무 테스트도 실시하여 각각의 공정 변수에 따른 결과를 비교 분석하였다.

• Journal of Power System Engineering
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• v.20 no.5
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• pp.20-28
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• 2016

This study has developed an organic/inorganic hybrid solution by addition of $SiO_2$ polysilicate and Melamine to the urethane. The three types of cold rolled steel were evaluated a corrosion resistance properties by using these solutions. The urethane solution(U) and the urethane solution with $SiO_2$ polysilicate($US_7$) were generate a lot of corrosion. The urethane solution with $SiO_2$ polysilicate and melamine($US_7M_3$) was excellent in corrosion resistance, regardless of the steel type. In addition, corrosion resistance has been shown to depend on the tensile strength. The appearance of coating by U and $US_7$ solution is bumpy surface, and were a lot of fine defects. $US_7M_3$ solution is made a sophisticated molecular cross-linking structure inside the coating, it was a slick surface. Other characteristics are exhibited the excellent property for all solutions.

• Journal of Institute of Control, Robotics and Systems
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• v.21 no.8
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• pp.742-747
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• 2015

The quality of steel plate products is determined by the number of defects and the process problems are estimated by shapes of defects. Therefore pinholes defects of cold rolled steel have to be controlled. In order to improve productivity and quality of products, within each production process, the product is inspected by an adequate inspection system individually in the lines of steelworks. Among a number of inspection systems, we focus on the pinholes detection system. In this paper, we propose an embedded system using FPGA which can detect pinholes defects. The proposed system is smaller and more flexible than a traditional system based on expensive frame grabbers and PC. In order to detect consecutive defects, FPGAs acquire two dimensional image and process the image in real time by using correlation of lines. The proposed pinholes detection algorithm decreases arithmetic operations of image processing and also we designed the hardware to shorten the data path between logics due to decreasing propagation delay. The experimental results show that the proposed embedded system detects the reliable number of pinholes in real time.

• Korean Journal of Materials Research
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• v.16 no.6
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• pp.386-393
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• 2006

Increasing environmental concerns require to solve the problem produced due to the use of heavy metals in coating formulations. Therefore, it is necessary to develop new coating strategy employing inherently conducting polymers such as polyaniline. Polyaniline is a conductive polymer that is synthesized by oxidation polymerization, and the electrochemical and chemical polymerization are possible for the oxidation of aniline. Electrochemical oxidation polymerization produces a fine surface and although voltage control is more convenient, it require electrolytic cells, and elaborate thin film can be acquired with the polymerization. Polyaniline films were electro-polymerized on cold rolled sheets using the galvanostat mode in the oxalic acidaniline-sodium molybdate electrolyte. The structure and properties of polyaniline film were studied using Potentiostat/Galvanostat 263A, FE-SEM,, AFM, SST, Colorimetry. A high corrosion resistance of polyaniline film was observed with an increase of corrosion potential by $500{\sim}600$ mV for the substrate covered with polyaniline.

• Journal of Welding and Joining
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• v.14 no.5
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• pp.59-68
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• 1996

This study was aimed to characterize the laser cutting process for the cold rolled stainless steel sheet. The principal process parameters of the cutting process were applied to both the continuous wave form and the pulsed wave form for the laser output mode. The laser-oxygen cutting process and the laser-nitrogen cutting process were also considered to characterize the quality and efficiency of the cutting process. The laser-oxygen cutting process revealed the better productivity than the laser-nitrogen cutting process, since the laser energy and the exothermic oxidation energy exerted on the laser-oxygen cutting process simultaneously during the entire cutting process. However, the straightness of the cutting section, which was considered as the most important factors, was inferior to that of the laser-nitrogen cutting process due to the formation of chromum oxide on the cutting surface. Frequency and duration of the pulsed wave form act as the main factors for the better quality, When the frequency increased from 100 Hz to 200 Hz and the duty increased from 20% to 40%, the quality factors such as the height of dross and the surface roughness were improved remarkably. The increase in the frequency from 200 Hz to 300 Hz, on the other hand, revealed the less effective in the cutting quality.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1993.10a
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• pp.512-517
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• 1993

The cold rolled strip meets continuously rising demands on the less deviation of thickness at the width direction of their rolled products. Especially, the special interest has been to find the methods to reduce the edge drop which influences seriously on the yield losses and the quality of the rolled products. In this study, the influence of hot coils on the thickness profile of cold rolled strip was analyzed. For obtainint the tapered work roll shig\ft conditions, the thermal crown and the flattening between the work roll and the strip were calculated, and the main parameters which have mostly effects on the edge drop were simulated. Also the obtained conditions from the simulation were applied to Tandem Cold Rolling Mill to investigate the change of the edge drop and the crown ratio depending on the amount of work roll taper and the length of contact of taper. The results of the application led to better thickness profile than conventional one.

• Journal of Welding and Joining
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• v.10 no.1
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• pp.52-59
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• 1992

Resistance spot weldability of cold rolled 80kg/mm$^{2}$ and 45kg/mm$^{2}$ grade high strength steel sheets for automobile structure was investigated focussing on the influences of welding parameters such as welding current and welding time on the weld strength and the nugget formation. The results of this study showed that the optimum ranges of welding current for the grade 80 and grade 45 were 5.0 cycle(250 m sec.) It was also shown that the tensile shear strength of the resistance spot weld was strongly influenced by both current and time applied in welding procedure, however, the tensile shear strength was mainly affected by welding time for the higher strength steel.

• Proceedings of the IEEK Conference
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• 2008.06a
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• pp.1047-1048
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• 2008

The objective of this paper is to build a decision method of the shape quality for the stainless steel and ensure reducibility of working-load for next rolling process. The criterion of the shape quality is derived from the customer needs, and Automatic Shape Decision System is implemented in SPM (Skin Pass Mill). The methods of shape decision are based on curve fitting and frequency analysis and so on. The Field Test with concerned customers is successful. The performance of right decision is 99% and the claims from the customer have been largely reduced.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.1499-1502
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• 2003

This paper describes the result of carbody and vibration test for freight car. The purpose of the test is to evaluate an safety which carbody structure shall be considered fully sufficient rigidity so as to load a freight car under maximum load and operating condition on line track. The test carbody is constructed by RS korea co., LTD. in accordance with KNR specfication. The test cases of the carbody is tested the vertical load and compressive load to verify the strength and stillness. The vibration test is tested for analysis and evaluation of vibration, to allow for the fact that mechanical vibration in railway vehicles have specific characteristics.

• Transactions of Materials Processing
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• v.19 no.4
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• pp.236-241
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• 2010

The frictional behavior of bare steel sheet highly depends on surface roughness. It was investigated that the change of surface roughness of bare steel sheet due to deformation for each forming mode. The flat type friction test was done to check the effect of surface roughness change on frictional characteristics of bare steel sheet. As increasing the deformation, the Ra value was increased at stretching forming mode and drawing forming mode, however the change of Pc showed different trends. The Pc was decreased as increasing stretch deformation but increased at compression deformation. At drawing forming mode, the friction coefficient was increased as deformation was increased after initial big drop with drawing oil. As deformation was increased, the friction coefficient was decreased with drawing oil at stretching forming mode. The results show that the deformation changes the surface roughness and frictional characteristics of steel sheet but the effect depends on the forming mode.