• Korean Journal of Fisheries and Aquatic Sciences
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• v.18 no.1
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• pp.8-14
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• 1985

A circulation water channel with observational section of $4m{\times}2.4m{\times}1m(length{\times}breadth{\times}depth)$ and the maximum channel flow speed of 2 m/sec was designed for model tests of fishing gears. It consists of 6 sections evenly divided for easy connection. Two observational acryl windows of $1.2m{\times}1.5m$ and 2cm thick are provided. Steel deflection plates, equally spaced in 20-40cm, are fixed at corners of the channel to reduce the loss of water pressure head through the channel. The flow in the channel is controlled by D.C. motor control system with 50 H.P. driving propeller system. A series of model testing capabilities for fishing gear have been examined and the results are as follows. 1) The speed of water flow was in the range from zero to 2.3 m/sec. 2) The difference between the velocity of channel flow along the center line and that along both sides in the channel was less than 0.2 m/sec.

• Journal of the Korean Society for Nondestructive Testing
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• v.22 no.1
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• pp.38-44
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• 2002

MFL method is a qualitative inspection tool and is a reliable, fast and economical NDT method. The application of MFL method to the inspection of storage tank floor plates has been shown to be a viable means. Examination of tank floors previously depended primarily upon ultrasonic test methods that required slow and painstaking application. Therefor most ultrasonic inspection of storage tank has been limited to spot testing only. Our NDE group have developed magnetic flux leakage system to overcome limitation of ultrasonic test. The developed system consists of magnetic yoke, array sensor, crawler and software. It is proved that the system is able to detect artificial flaw like 3.2mm diameter, 1.2mm depth in 6mm thick steel plate.

• Steel and Composite Structures
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• v.31 no.5
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• pp.503-516
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• 2019

This work presents a dynamic investigation of functionally graded (FG) plates resting on elastic foundation using a simple quasi-3D higher shear deformation theory (quasi-3D HSDT) in which the stretching effect is considered. The culmination of this theory is that in addition to taking into account the effect of thickness extension (${\varepsilon}_z{\neq}0$), the kinematic is defined with only 4 unknowns, which is even lower than the first order shear deformation theory (FSDT). The elastic foundation is included in the formulation using the Pasternak mathematical model. The governing equations are deduced through the Hamilton's principle. These equations are then solved via closed-type solutions of the Navier type. The fundamental frequencies are predicted by solving the eigenvalue problem. The degree of accuracy of present solutions can be shown by comparing it to the 3D solution and other closed-form solutions available in the literature.

• Korean Journal of Metals and Materials
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• v.47 no.12
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• pp.811-818
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• 2009

In order to meet increasingly complex and rigorous technical specifications, extensive effort has been devoted to fabricate clad materials with multi-layered metal plates. In this study, novel stainless steel/aluminum/copper (STS/Al/Cu) three-ply clad materials were fabricated by a hot rolling process for cookware applications. The effect of the testing temperature on the mechanical properties of the clad materials and on each component metal was investigated during the tensile tests. The interface properties of the clad materials were also examined by optical microscopy (OM) and an electron probe micro-analyzer (EPMA). The best mechanical and interfacial properties for a warm working process were found in a sample annealed at a temperature of $300^{\circ}C$. For the sample annealed at $400^{\circ}C$, the results of the tensile test indicated that interface delamination occurred only in the region of the Al/Cu interfaces. This was due to the formation of the thick and brittle intermetallic compound of $Al_2Cu$ in the Al/Cu interface. In contrast, no interface delamination was observed in the STS/Al interface, most likely due to its strong bond strength.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.3
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• pp.88-93
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• 2021

SAW (Submerged Arc Welding) is often used for ship construction or welding pressure vessels and involves spraying a flux in a powder form to a welding site to a certain thickness and continuously supplying electrode wires therein. This welding method enables high current welding up to 1,500 to 3,000 A. Arc efficiency is higher than 95% and the technique allows clean work as it creates less welding fume, which is composed of fine metal oxide particles, and the arc beam is not exposed. In this study, SM490C-TMC thick plates were heterogeneously welded by SAW. Mechanical properties of welds were measured, and welds were assessed macroscopically and for adhering magnetic particles. The following conclusions were drawn. Bending tests showed no spots exploded on sample surfaces or any other defect, and plastic deformation testing confirmed sufficient weld toughness. These results showed the 1F welding method has no shortcomings in terms of bending performance.

• Journal of Korean Society of Steel Construction
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• v.21 no.6
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• pp.585-596
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• 2009

In the construction of end-plate connections, the end-plate is welded to the end of the beam in a factory and fastened by bolts in the field. This connection is widely used in advanced countries such as European countries and the U.S. Its design and connection details are prescribed in Eurocode 3, AISC LRFD, and FEMA 350. In Korea, the standards for seismic design in KBC 2005 have been reinforced based on IBC 2000 in the U.S., and it is expected that the connection details in the U.S. will be adopted for the establishment of beam-to-column design standards. In the U.S. thick end-plates are used for the connections to prevent beam rupture. The use of the connections in Korea, however, may lead toover-design. In this experimental study, the design standards for the end-plate connections provided by FEMA-350 were analyzed and structural tests for six specimens were conducted with the variables being the shim plate and the connection shape, to provide the best specifications for connections with plastic deformation in the end-plate for use in Korea.