• Journal of the Korean Geotechnical Society
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• v.23 no.4
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• pp.79-90
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• 2007

Behaviors of instrumented steel sheet piles which are installed in sand ground by vibratory hammer were investigated. Especially, stresses acting on the pile during vibratory driving, efficiency factor which reflects differences between theoretical driving force and actually delivered acting force, justifiability of rigidity of steel sheet pile, dynamic resistance characteristics of soil and penetration characteristics of sheet pile were analysed. According to the field test results it is justifiable that steel sheet pile behaves as a rigid body during vibratory driving. And it can be seen that maximum stress acting on sheet pile section is far less than tensile strength of the material. Value of the maximum section force at sheet pile head was 72% of that estimated from theoretical equation. Magnitudes of displacement amplitudes computed from displacement-time history curve corresponding to four penetration depths were in the range of 16 $\sim$ 75% of that specified by manufacturer.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.50 no.4
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• pp.388-395
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• 2017

We investigated the toxicity of zinc and aluminum hot-dip galvanized sheet steel to abalone Haliotis discus hannai via changes in the gill and hepatopancreas using histological and transmission electron microscopy analysis. Experimental groups were composed of one control and four exposure conditions (direct or indirect exposure to zinc and aluminum hot-dip galvanized sheet steel). In the control group, aluminum exposure groups (direct and indirect), and indirect zinc exposure group, abalone mortality was not observed until the end of the experiment, and no histopathological changes were observed in the gill and hepatopancreas. However, the direct zinc exposure group exhibited 100% mortality. Ultrastructural analysis of the cytoplasm of ciliated and microvilli-bearing epithelial cells from gill filaments revealed electron-dense vesicles near the cell membrane and disruption of the nuclear membrane. We also observed swollen mitochondria and a loss of mitochondrial cristae. The hepatopancreas showed similar changes, and we detected highly electron-dense particles within the vesicles. These results suggest that abalone exposed directly to zinc hot-dip galvanized sheet steel experience acute toxicity, causing damage to cell organelles in the gill and hepatopancreas and, finally, inducing mortality.

• Journal of Radiation Protection and Research
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• v.31 no.3
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• pp.149-153
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• 2006

An ionization chamber is still widely used in many fields by virtue of its' simple operational characteristics and the possibility of its' various shapes. A parallel type of an ionization chamber for a steel sheet thickness measurement was designed and fabricated. High pure xenon gas, which was pressurized up to 6 atm, was chosen as a filling gas to increase the current response and sensitivity for a radiation. A high pressure gas system was also constructed. The active volume and the incident window size of the fabricated ionization chamber were $30\;cm^3\;and\;12\;cm^2$, respectively. Preliminary tests with a 25 mCi $^{241}Am$ gamma-ray source and evaluation tests in a standard X-ray field were performed. The optimal operation voltage was set from the results of the collection efficiency calculation by using an experimental two-voltage method. Linearity for a variation of the steel sheet thickness, which is the most important factor for an application during a steel sheet thickness measurement, was 0.989 in this study.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.7
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• pp.1167-1174
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• 2008

The measurement of two-dimensional magnetic properties of electrical steel sheet using single sheet tester (SST) requires to control the B-waveform as sinusoidal. The SST electric circuit, in general, has inductance, and this makes the phase lag in electric current. For this reason, the induced voltages of H- or B-coil may have phase difference from the exciting voltage. In this paper, a new algorithm is developed to compensate the phase difference and makes the B-waveform control efficient. The developed algorithm experimentally calculates the phase difference based on the measured waveform of the induced voltage for the magnetic field intensity along transverse direction. By using the proposed algorithm, the two-dimensional magnetic properties of grain-orientated electrical steel sheet (30PG110) is measured up to 2T. By comparing the measured B- and H-waveforms, the effectiveness of the proposed algorithm is proven.

• Proceedings of the Korean Geotechical Society Conference
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• 1994.09a
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• pp.111-118
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• 1994

The use of steel sheet pile walls as barrier walls have the temporary for coffer dam, retaining wall in excavation, etc., but also permanent of semi-permanent for harbor construction, containment systems, vertical barrier systems for waste disposal (landfill) or subway in excavarion. In all these applicaions the resistance of the structure to seepage plays an important role. Also the stability and longevity of the construction, the possibility of permanent control and survey make the steel sheet pile wall a nearly perfect vertical barrier from a technical and economical point of view.

• Proceedings of the KWS Conference
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• 2005.06a
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• pp.247-249
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• 2005

Evaluation and prediction of fatigue crack initiation life in EZNCEN(Galvanized steel sheet) and HS40R(High strength steel sheet) tensile-shear spot weldment were studied by using DCPDM(DC Potential Drop Method)

• Transactions of Materials Processing
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• v.7 no.2
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• pp.150-157
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• 1998

Recently the SPPC technology is being developed in steel rolling industries for the purpose of enhancing mechanical properties of rolled sheets. The technology is to produce steel sheets with finer and more uniformly distributed grains by prediction of recrystallization behaviors and on-line control of rolling parameters during hot rolling process. In this study a finish rolling process was analyzed by a three-dimensional rigid-thermoviscoplastic finite element method and recrystallization behaviors of several locations in the sheet were predicted by Sellars equations. As a result it was found that the initial grain size of 84 ${\mu}m$ became $21-23\;{\mu}m\;20-22{\mu}m\;and\;18-20{\mu}m$ at front middle and end portions of the sheet respectively. It was also found that variations of the grain size became $$0.6{\sim}2{\mu}m\;and\;10{\mu}\mum$$ in thickness and width directions respectively.

• Journal of Welding and Joining
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• v.21 no.4
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• pp.56-62
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• 2003

MIG brazing is used for many parts without melting base metal because of high productivity. Pulsed MIG brazing can be used to further reduce heat input and to improve the process stability. However, a significant amount of zinc in galvanized sheet steel is burned off in the area of brazes. Therefore, the brazing method to reduce the heat input is needed. In the brazing for galvanized sheet steel, variable polarity AC pulse MIG arc brazing can be applied to more decrease the heat input by setting EN-ratio adequately. In this research, we studied for the variable polarity AC pulse MIG arc brazing to decrease the heat input by using ERCuSi-A wire. As the result of increasing EN-ratio, melting ratio of base metal and burning off of zinc were reduced in galvanized sheet steel.

• IE interfaces
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• v.16 no.2
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• pp.248-257
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• 2003

In a heated rolling process of a steel mill where steel plates are pressed to a sheet coil by spreading and expanding, an irregularly-shaped head portion as well as a tail portion of the sheet coil need to be cropped. Any crop which is not clearly cut and separated from the sheet coil may cause critical damages to the facilities of the following processes. As the cropping process is performed very fast, human eyes are not proper for continuous monitoring of the cropping process. To solve this problem, we have developed a machine-vision based crop-drop detection system. The system also measures lengths of major and minor axes for the crops and thereby determines the proper crop size to minimize steel sheet losses.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2005.05a
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• pp.389-392
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• 2005

In the modern days, a galvannealed sheet steel(GA) instead of a cold rolled steel sheet has been widely used as an alternative to extend the life of automotive body. Accordingly, the mechanical properties of GA for automobiles were taken Into account and studied by comparing with the temperature variation on annealing in this study. To clarify the effect of surface features in the mechanical properties of GA, the several tests such as nanoindentation and FE-analysis were executed. For this goal use is made of the method of neural networks. The developed neural networks apply also to obtain reliable mechanical properties of the thin films. Load-displacement curve was computed by the analysis procedure and compared with experimental results.