• Proceedings of the KSR Conference
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• 2011.10a
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• pp.2672-2678
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• 2011

Carbody of rolling stock has been gradually changed as whole wood, steel frame with wood car body, whole steel car body with rivet and whole monocoque carbody with welding. And also mild steel has been used widely to material of structure, but usage of stainless and aluminium which have lightweight and high corrosion resistance is being increased lately. Structure is being commercialized to AED(All Extrusion Design),whole double skin with hollow excluded shape such as aluminium structure from SSD(Sheet Stringer Design), single skin consists of traditional frame and outside plat. Traditional aluminium carbody had many problems from reduced strength in welding combination section because car body is consist of small extruded material affected heat by welding. On this study, we proposed the plan to improve the body strength and quality with large-scale aluminium extruded material by minimizing welding concentration in combination section.

• Proceedings of the Korean Society of Laser Processing Conference
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• 2002.05a
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• pp.65-70
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• 2002

• Proceedings of the KWS Conference
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• 2002.05a
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• pp.232-235
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• 2002

• Proceedings of the Korean Nuclear Society Conference
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• 2003.10a
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• pp.418-418
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• 2003

• Transactions of the Korean Society of Mechanical Engineers
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• v.2 no.3
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• pp.53-61
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• 1978

This study has been concentrated on the relations between the crack growth rate and the stress intensity factor, the fatigue limit and finally on the condition of the crack propagation along the laminated cross section of the laminated steel under the repeated plane bending through tests. The following results are obtained. 1. The fatigue limit of the laminated steel is higher than the single steel 2. The realtion between the fatigue crack growth rate, dL/dN and Stress intensity factor are ; dL/dN = 2.14 * 10$^{-11}$ $K^{2.95}$ for SUP 9 dL/dN = 1.70 * 10$^{-11}$ $K^{2.95}$ for SMS dL/dN = 9.77 * 10$^{-11}$ $K^{2.95}$ for SPMS dL/dN = 3.57 * 10$^{-8}$ $K^{1.53}$ for SPMM dL/dN = 5.5O * 10$^{-8}$ $K^{1.53}$ for MLD 3. The crack propagation of the laminated steel also tends to be completed through 3 steps; The first step proceeds swiftly, in a second slowly for a long time and last very rapidly for a short moments.

• Journal of the Korean institute of surface engineering
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• v.54 no.6
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• pp.371-379
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• 2021

The use of anti-corrosive oil (AC) is inevitable for production of industrial steels to prevent corrosion. The AC is degreased before application of steels, which crucially effects on final products, such as automobile, electricity etc. However, qualitative/quantitative evaluation of degreasing performance are steal insufficient. In this study, degreasing performance of anti-corrosive oil on steel have been studied through X-ray photon spectroscopy (XPS) and electrochemical impedance spectroscopy (EIS). Commercial automotive steels (AMS) are coated with 4 different anti-corrosive oils (namely AC1-AC4). In XPS, intensity of C1s peak remained after degreasing indirectly indicates incomplete degreasing. Thus, higher C1s peak intensity means less effective degreasing by degreasing agent. peak intensity of C1s peak shows opposite tendency of peak intensity of O1s. We found that EIS analysis is not applicable to mild steel (such as AMS1) due to corrosion during measurement. However, alloy steel can be fully analyzed by EIS and XPS depth profile.

• Journal of the Korean Society of Marine Environment & Safety
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• v.27 no.3
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• pp.447-456
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• 2021

Methods for predicting the ultimate/buckling strength of ship structures have been extensively improved in terms of design formulas and analytical solutions. In recent years, the design strategy of ships and offshore structures has tended to emphasize lighter builds and improve operational safety. Therefore, the corresponding geometrical changes in design necessitate the use of high-tensile steel and thin plates. However, the existing design formulas were mainly developed for thick plates and mild steels. Therefore, the calculation methods require appropriate modification for new designs beased on high-tensile steel and thin plates. In this study, a modified formula was developed to predict the ultimate strength of thin steel plates subjected to compressive and shear loads. Based on the numerical results, the effects of the yield stress, slenderness ratio, and loading condition on the buckling/ultimate strength of steel plates were examined, and a newly modified double-beta parameter formula was developed. The results were used to derive and modify existing closed-form expressions and empirical formulas to predict the ultimate strength of thin-walled steel structures.

• Journal of Advanced Marine Engineering and Technology
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• v.25 no.6
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• pp.1336-1340
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• 2001

Due to increase of air pollution substance, such as $SO_2$,$SO_3$, H2S ,CO, HCI, $Cl_2$ and so on, the operating environment of mechanical equipment and facilities like generating plants, ships, metal structure etc., are acidified and corroded. In these environments, the crevice corrosion of marine facilities frequently occurs at crevice like jointed bolt, gasket or sealant, riveted plates, contact of metal with non-metallic solids etc. Therefore, this paper was studied on the crevice corrosion behavior of mild steel(SS 400) in marine environment. In a variety of NaCl solutions, the aspect of he .crevice corrosion and polarization behavior under the crevice corrosion was investigated. The main results obtained are as follows: 1) Under crevice corrosion, the open circuit potential become less treble as the concentration of NaCl solution increased. 2) The corrosion current density of mild steel was high drained as the concentration of NaCl solution increased by 3.5%, but in the concentration increased over 3.5%, the corrosion current density was low drained. 3) The crevice corrosion is more sensitive to the synergy effect of dissolved oxygen and NaCl.

• 유체기계공업학회:학술대회논문집
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• 2000.12a
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• pp.373-378
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• 2000

The crevice corrosion of local corrosion occur when the gap exist on metal surface. This crevice corrosion happen to region such as flange of pipe, contact part of casing, under gasket and packing, between valve disk and seat of pump etc. Especially The crevice corrosion of mild steel(SS 400) get serious. This paper was studied on the crevice corrosion of SS 400 in fluid environment. In $0\%,\;2\%,\;3.5\%,\;5\% NaCl$ solution, the aspect of the crevice corrosion and polarization behavior under the crevice corrosion was investigated. And Weight loss rate of SS 400 with crevice and non-crevice was measured according to the NaCl concentration. The main results obtained are as follows : 1) Under crevice corrosion, the corrosion potential become less noble as the concentration of NaCl solution increased. 2) The current density under open circuit potential was high drained as concentration of NaCl solution increased by $3.5\%$ but the concentration increased over $3.5\%$, the current density was low drained. 3) The weight loss rate of SS 400 was increased as concentration of NaCl solution Increased by $3.5\%$, but the concentration increased over $3.5\%$, that of SS 400 was decreased. 4) Effect of oxygen for crevice corrosion in the concentration of $3.5\%$ NaCl solution become sensitive than that $0\%$ NaCl solution.

• Smart Structures and Systems
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• v.19 no.3
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• pp.299-307
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• 2017

The magneto-electro-elastic (MEE) material under thermal environment exhibits pyroelectric and pyromagnetic coefficients resulting in pyroelectric and pyromagnetic effects. The pyroelectric and pyromagnetic effects on the behavior of multiphase MEE sensors bonded on top surface of a mild steel beam under thermal environment is presented in this paper. The aim of the study is to find out how samples having different volume fractions of the multiphase MEE composite behave in sensor applications. This is studied at optimal location on the beam, where the maximum electric and magnetic potentials are induced due to pyroelectric and pyromagnetic effects under clamped-free and clamped-clamped boundary conditions. The sensor which is bonded on the top surface of the beam is modeled using 8-node brick element. The MEE sensor bonded on mild steel beam is subjected to uniform temperature rise of 50K. It is assumed that beam and sensor is perfectly bonded to each other. The maximum pyroelectric and pyromagnetic effects on electric and magnetic potentials are observed when volume fraction is ${\nu}_f=0.2$. The boundary conditions significantly influence the pyroelectric and pyromagnetic effects on electric and magnetic potentials.