• Journal of Advanced Marine Engineering and Technology
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• v.24 no.3
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• pp.20-28
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• 2000

Air wiping technique is widely used because of easy and efficient coating control in present CGL The coating weight is controlled by nozzle header pressure. strip line speed, and the distance between strip and nozzle. Coating defects are resulted from the unbalance of these control factors and the inaccuracy of coating equipments. We investigates the main cause of coating defects, such as edge overcoating and coating deviation through various experiments. It is found that the edge overcoating is mainly come from nozzle lip type, and the coating deviation is caused by the unbalance of dynamic pressure.

• Journal of Advanced Marine Engineering and Technology
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• v.26 no.2
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• pp.192-199
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• 2002

In continuous galvanizing process, the mass of zinc deposited and its distribution are controlled by the air pressure, effective distance from the air knife nozzle to the steel strip surface and line speed. Coating defects are resulted from the unbalance of these control factors and the inaccuracy of coating equipments. This paper investigates the main cause of coating deviation and a new air knife system for control of coating thickness was developed. We investigate dynamic pressure variation by air knife types. It is found that the coating deviation is caused by the unbalance of dynamic pressure, the irregularity of strip position, and the strip vibration. Formulating a useful coating model by using present working condition, an optimal working condition is suggested. The productivity and coating quality are improved by applying the result of this research at the shop floor.

• Journal of the Korean Society for Precision Engineering
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• v.10 no.3
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• pp.57-68
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• 1993

Air Wiping technique is widely used because of easy and efficient coating control in present CGL. Coaring weight is decided by nozzle header pressure, strip line speed and distance between strip and nozzle. Coating defects are results from unbalance of these factors and coating equipment calibration inaccuracy. Therefore, this study is mainly dealing with the cause of coating defects such as edge overcoating and coating deviation. The coptimum working condition is suggested by formulated coating model using collected working data. We developed two demension analysis program for air flow in nozzle and calculated dynamic pressure and air velocity with this program. The productivity and coating guality are improved by applying the result of this reserach.

• Proceedings of the KWS Conference
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• 2009.11a
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• pp.118-118
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• 2009

자동차의 경량화, 안전성 그리고 내식성 향상을 위하여 고강도 강판 및 도금 강판의 적용이 증가하면서 자동차 산업의 많은 부분에서 적용되는 저항 점용접에서도 고강도 강판과 도금강판의 적용이 증가하는 추세이다. 이에 따라 고강도 강판과 도금 강판의 낮은 용접성을 개선하기 위하여 기존의 단상 AC 용접기에서 전류 파형의 형태를 개선한 인버터 DC 용접기가 차체 조립라인에서 많이 사용되고 있다. 본 연구에서는 고강도 강판의 저항 점용접의 연속타점 시 단상 AC용접기와 인버터 DC용접기의 전극의 연속타점 수명의 차이를 비교하고 분석하기 위해 590MPa 급 전기아연도금강판을 이용하여 AWS 규격에 연속타점실험을 기준으로 단상 AC 와 인버터 DC 용접기의 연속타점 실험을 실시하였다. 연속타점실험 중에 전극의 형상관찰을 위해 100타점 간격으로 carbon paper를 이용해 전극 직경 변화를 관찰 하였으며, 100 타점간격으로 동저항을 측정하고 인장 전단 시편과 Peel test 시편을 제작하여 연속타점 시 단상 AC와 인버터 DC 용접기의 저항 점용접 연속타점 수명을 비교 분석하였다. 그리고 연속타점 실험 후 사용된 전극의 표면과 단면 형상을 각각 OM, SEM, EDX로 분석하여 전극 표면의 Zn과 합금화 된 전극의 합금층을 분석하였다. 그 결과 590MPa급 전기아연도금강판의 저항 점용점 연속타점 수명평가에서 인버터 DC 용접기가 단상 AC 용접기보다 200타점 더 우수한 연속타점 수명을 보유하였다. 특히 인장강도 기준 측면에서는 인버터 DC 용접기의 전극 연속타점수명은 매우 우수하다.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.11b
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• pp.1010-1014
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• 2001

A severe strip vibration in continuous galvanizing line facilities of the steel companies has sometimes occurred due to the exceeding wearing of the roll bush and bearing. This vibration brings on the lack of uniform coating thickness in steel plate. As a result, the total maintenance and product costs in this factory are increased by the shortage of operation time for the replacement of bush, bearings and these components. In this study, the vibration characteristics of this strip are investigated by the FEM using ANSYS. Also the vibration measurement of strip and its structure performed by the laser Doppler vibrometer(LDV) and accelerometers are compared to theoretical analysis results.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1999.08a
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• pp.111-118
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• 1999

This article describes the basic engineering concepts to be considered in the application of an induction heating furnace in the hot-dip galvanizing line. Experience in the Dongkuk project in Pohang, has shown that this arrangement has many advantages over the conventional method of using a combustion-gas heated furnace. Investment and operating costs are lower, the line length is much shorter, line operation is more convenient, air pollution is reduced, and the coated strip at of top-quality. As these benefits become well known, it is anticipated that the concept of induction heating will be more widely used in both new and revamped process lines. Induction heating is suitable for the production of Commercial Quality hot galvanized coils. More research is required to extend the present concept to the production of higher forming grades such as Drawing, Deep Drawing and Extra Deep Drawing Quality steels. A combination of induction heating and combustion-gas heating may lead to the way to the processing of these qualities of strip.

• Journal of Hydrogen and New Energy
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• v.31 no.1
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• pp.23-32
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• 2020

The intermittent characteristics of renewable energy complicates the process of balancing supply with demand. Electrolysis technology can provide flexibility to grid management by converting electricity to hydrogen. Alkaline electrolysis has been recognized as established technology and utilized in industry for over 100 years. However, high overpotential of oxygen evolution reaction in alkaline water electrolysis reduces the overall efficiency and therefore requires the development of anode catalyst. In this study, Raney Ni-Zn-Fe electrode was prepared by electroplating and the electrode characteristics was studied by varying electroplating parameters like electrodeposition time, current density and substrate. The prepared Raney Ni-Zn-Fe electrode was electrochemically evaluated using linear sweep voltammetry. Physical and chemical analysis were conducted by scanning electron microscope, energy dispersive spectrometer, and X-ray diffraction. The plating time did not changed the morphology and composition of the electrode surface and showed a little effect on overpotential reduction. As the plating current density increased, Fe content on the surface increased and cauliflower-like structure appeared on the electrode surface. In particular, the overpotential of the electrode, which was prepared at the plating current density of 320 mA/㎠, has showed the lowest value of 268 mV at 50 mA/㎠. There was no distinguishable overpotential difference between the type of substrate for the electrodes prepared at 80 mA/㎠.

• Journal of Institute of Control, Robotics and Systems
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• v.21 no.8
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• pp.718-722
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• 2015

This paper proposes a fractional-order PID (Proportional-Integral-Derivative) control used electromagnetic strip stabilization controller in a continuous galvanizing line. Compared to a conventional PID controller, a fractional-order PID controller has integration-fractional-order and derivation-fractional-order as additional control parameters. Thanks to increased control parameters, more precise controller adjustment is available. In addition, accurate transfer function of a real system generally has a fractional-order form. Therefore, it is more adequate to use a fractional-order PID controller than a conventional PID controller for a real world system. Finite element models of a $1200{\times}2000{\times}0.8mm$ strip, which were extracted using a commercial software ANSYS were used as simulation plants, and Gaussian mixture models were used to find optimized control parameters that can reduce the strip vibrations to the lowest amplitude. Simulation results show that a fractional-order PID controller significantly reduces strip vibration and transient response time than a conventional PID controller.

• Journal of Hydrogen and New Energy
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• v.29 no.6
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• pp.549-558
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• 2018

The overall efficiency depend on the overpotential of the oxygen evolution reaction in alkaline water electrolysis. Therefore, it is necessary to research to reduce the oxygen evolution overpotential of electrodes. In this study, Ni-Zn-Fe electrodes were prepared by electroplating and the surface area was increased by Zn leaching process. Electroplating variables were studied to optimize the plating parameters(electroplating current density, pH value of electroplating solution, Ni/Fe content ratio). Ni-Zn-Fe electrode, which is electroplated in a modified Watts bath, showed 0.294 V of overpotential at $0.1A/cm^2$. That result is better than that of Ni and Ni-Zn plated electrodes. As the electroplating current density of the Ni-Zn-Fe electrode increased, the particle size tended to increase and the overpotential of oxygen evolution reaction decreased. As reducing pH of electroplating solution from 4 to 2, Fe content in electrode and activity of oxygen evolution reaction decreased.