• Journal of Welding and Joining
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• v.27 no.3
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• pp.85-91
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• 2009

A roll projection welding machine is introduced to fabricate metallic sandwich plate consisting of a structured inner sheet with projection-like shape and a pair of skin sheets. To fabricate the metallic sandwich plate of consistent and good quality, two process monitoring methods are introduced; dynamic resistance monitoring and skin sheet temperature monitoring. Dynamic resistance monitoring has no time delay but gives only averaged value over plate width. Skin sheet temperature monitoring has certain amount of time delay but is good for predicting weld quality of specified position. By the two complementary monitoring methods, the characteristics of the new welding process is successfully understood.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.11a
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• pp.853-856
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• 2004

This study presents a prediction method for sound insulation of sandwich plate which consists of orthotropic plates as skin and mineral wool as core. Prediction by classic theory, which considers orthotropic effects, requires considerably complex and cumbersome process and moreover many assumption. However, experimental results of the sandwich plate with orthotropic plates as skin show that the orthotropic effects are disappeared or fade out. Hence, predictions by using sandwich model are conducted by a simple modelling that substitutes an orthotropic plate into an equivalent flat plate. Comparative results show that sandwich model gives a good agreements with theoretical prediction.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2000.11a
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• pp.199-202
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• 2000

Compared with existing construction materials, ACM(Advanced Composites Material) possesses many advantage such as light-weight, high-strength, corrosion resistant properties, etc. In this study, utilizing those advantages of ACM, composite skin and comer plate for protection of concrete port structure are developed. Detailed procedure fur analysis, design and fabrication along with site installation for demonstration project are described. It is also demonstrated that pultrusion process for comer plate and VARTM process for composite skin are promising fabrication methods fer future civil infrastructure application.

• International Journal of Korean Welding Society
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• v.5 no.1
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• pp.29-34
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• 2005

Finite element analysis (FEA) and experimental studies on an elastic bending method have been performed in order to control the angular distortion at the fillet weldment for curved panel. Process parameters for the elastic bending method such as clamping span and release time were analyzed with reference to welding condition and geometric effect of the curved panel, which can minimize or prevent the angular distortion by producing a proper skin stress to the fillet weldment. The amounts of the angular distortion decrease almost in a linear manner with an increase in the skin stress. The skin stress required for non-angular distortion at the fillet weldment is strongly dependent on the plate thickness, not the heat intensity applied. The clamping span for obtaining uniform skin stress was defined as functions of the plate thickness and length of the free edge. Clamp should be removed after the fillet weldment is cooled down to room temperature for non-angular distortion. Effectiveness of the elastic bending method established was verified by its application to an actual curved panel.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.22 no.4
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• pp.217-239
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• 2018

This paper examined the MHD and thermal behavior of unsteady mixed convection flow of a rotating fluid in a porous parallel plate channel in the presence of Hall current and heat source. The exact solutions of the concentration, energy and momentum equations are obtained. The influence of each governing parameter on non dimensional velocity, temperature, concentration, skin friction coefficient, rate of heat transfer and rate of mass transfer at the porous parallel plate channel surfaces is discussed. During the course of numerical computation, it is observed that as Hall current parameter and Soret number at the porous channel surfaces increases, the primary and secondary velocity profiles are increases while the primary and secondary skin friction coefficients are increases at the cold wall and decreases at the heated wall. In particular, it is noticed that a reverse trend in case of heat source parameter.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.14 no.3
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• pp.267-276
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• 2001

On the basis of structural analysis of the radial gate(that is, Tainter gate), this paper focuses on the optimization of the moment distribution according to the location of the arm of the radial gate. In spite of its importance from economical view point, we could hardly find the study on the optimum design of radial gate. Accordingly, the present study identifies the optimum section modulus for a radial arm along with the optimum position for 2 of 3 radial arms with a convex cylindrical skin plate relative to a given radius of the skin plate curvature, pivot point, water depth, ice pressure, etc. These optimum measurements are then compared with previously constructed radial gates. The results indicate that the optimum section modulus vague for a radial arm was appreciably smaller than the previously constructed examples.

• Journal of the Korean Wood Science and Technology
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• v.38 no.4
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• pp.282-291
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• 2010

As compared with existing center-boring timber, skin timber which be hollowed out of its considerable inner parts has some merits as like short drying time, less developed checks during drying, a advantage of lower MC (8~%), more easy injection of chemicals, a possibility of using as a lighter structural heavy timber including Hanok and heavy timber construction, a possibility for the various living necessaries and furniture materials. However, development of hybrid skin timber is required for using as a value-added materials and giving a confidence for the structural safety of skin timber to general user. Thus, improved pine skin timber (IPST) and improved larch skin timber (ILST) were manufactured using the lighter steel plate possible. And compressive capacity of improved skin timber was analyzed. From the results of this study, the following conclusions have been made: 1. Both of IPST and ILST can give a uniformity of material capacity compared with non-treated skin timber. 2. Both IPST and ILST, there was not statistical significancy among the thickness of steel plate. Therefore, it concluded that it was not necessary to use thicker steel plate. 3. There was also not statistical significancy between IPSR and ILST, so it need not to be selective about the species of improved skin timber. 4. IPST showed various failure types, but most failure types of ILST is a splitting type.

• Korean Journal of Veterinary Service
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• v.22 no.4
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• pp.411-418
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• 1999

In this studies, the ability of chlorine and lactic acid to reduce bacterial population of the pathogenic microorganisms were examined on artificially inoculated chicken skin. About 10$^{5}$ cells of staphylococcus aureus, salmonella enteritidis, listeria monocytogenes and escherichia coli O157:H7 were inoculated in chicken skin. The contaminated samples were washed for 1 min with sodium hypochlorite solutions that contained 2, 5, 10, 20 and 50mg/$\ell$ available chlorine and counted number of the agents. Viable population were no significantly difference (p$\geq$0.05) between concentration of chlorine and strains of the pathogens. In the samples inoculated with pathogens were washed in 20mg/$\ell$ chlorine and then stored at $^5{\circ}C$ for up to 10 days, the initial counts of psychrotrophs and aerobic plate counts were 4.02 to 4.36 log cfu/$\textrm{cm}^2$ and increased slightly in course of time. But 10 days after, the pathogens were a little reduced from 3.66~4.91 log cfu/$\textrm{cm}^2$ to 2.54~4.66 log cfu/$\textrm{cm}^2$. In the case of washed skin with solution of 20mg/$\ell$ chlorine and 0.5% lactic acid then store at $^5{\circ}C$ for up to 10 days, population of psychrotrophs and aerobic plate counts on chicken skin were markedly reduced immediately after treatment, but the numbers of contaminants were slightly increased after 6 and 8 days. Specifically, numbers of St aureus, S enteritidis, L monocytogenes and E coli O157:H7 were reduced to 0.5, 0.4, 0.3 and 1.15 log cfu/$\textrm{cm}^2$ after 10 days of storage, respectively, on aerobic plate counts.

• Steel and Composite Structures
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• v.26 no.3
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• pp.329-345
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• 2018

This paper systematically investigated the mechanical performance of the weak-axis cover-plate connection, including a beam end monotonic loading test and a column top cyclic loading test, and a series of parametric studies for exterior and interior joints under cyclic loading using a nonlinear finite element analysis program ABAQUS, focusing on the influences of the shape of top cover-plate, the length and thickness of the cover-plate, the thickness of the skin plate, and the steel material grade. Results showed that the strains at both edges of the beam flange were greater than the middle's, thus it is necessary to take some technical methods to ensure the construction quality of the beam flange groove weld. The plastic rotation of the exterior joint can satisfy the requirement of FEMA-267 (1995) of 0.03 rad, while only one side connection of interior joint satisfied ANSI/AISC 341-10 under the column top cyclic loading. Changing the shape or the thickness or the length of the cover-plate did not significantly affect the mechanical behaviors of frame joints no matter in exterior joints or interior joints. The length and thickness of the cover-plate recommended by FEMA 267 (1995) is also suitable to the weak-axis cover-plate joint. The minimum skin plate thickness and a design procedure for the weak-axis cover-plate connections were proposed finally.

• Steel and Composite Structures
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• v.26 no.1
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• pp.31-44
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• 2018

This paper reports a novel steel beam-to-column connection suitable for use in the weak axis of I-section column. Monotonic and cyclic loading experimental investigations and numerical analysis of the proposed weak-axis connection were conducted, and the calculation procedure of the beam-column relative rotation angle and plastic rotation angle was developed and described in details. A comparative analysis of mechanical property and steel consumption were employed for the proposed I-section column weak-axis connection and box-section column bending connection. The result showed that no signs of fracturing were observed and the plastic hinge formed reliably in the beam section away from the skin plate under the beam end monotonic loading, and the plastic hinge formed much closer to the skin plate under the beam end cyclic loading. The fracture of welds between diaphragm and skin plate would cause an unstable hysteretic response under the column top horizontal cyclic loading. The proposed weak-axis connection system could not only simplify the design calculation progress when I-section column is adopted in frame structural design but also effectively satisfy the requirements of 'strong joint and weak member', as well as lower steel consumption.