• Journal of the Korean Society for Nondestructive Testing
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• v.13 no.1
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• pp.40-45
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• 1993

The steam generator tubes of the nuclear power plant should be inspected using eddy current techniques. Recently the crack-like defects become a major concern for the integrity of the steam generator tubes. These defects could be detected by the MRPC(Motorized Rotating Pancake Coil) method, not by the conventional bobbin coil method. In this paper it has been attempted to estimate the length of the cracks at the tube expansion region using of MRPC technique. The lengths of both axial and circumferential cracks show a tendency of overestimation compared to the real lengths. As the depths of the defects decrease from 100% through 50% of the wall thickness, the error of the length estimation is increased.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.5 no.2
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• pp.35-39
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• 1985

The closed form of the stiffness matrix is derived in terms of closed forms of intergrals for analyses of plane frame members containing linerly tapered members with the cross section of thin-walled tube. The series expansion forms of these are also developed to study the errors in the closed form of the stiffness matrix. The useful limits of the closed form of integrals are defined in terms of the relative taper.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.5
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• pp.1280-1290
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• 1995

In order to investigate the compression wave propagating in a high-speed railway tunnel, a numerical calculation was applied to the wave phenomenon occurring in a model tunnel. Unsteady, one-dimensional inviscid or viscous flows were solved by an explicit TVD scheme, and the calculated flows were compared with the results of measurement in real tunnels. Tunnel noises caused by emission of the compression wave were characterized in terms of excess pressure of compression wave, pressure gradient in the wave front and width of the compression wave. Calculated attenuation, pressure gradient and width of compression wave with the propagating distance agreed with the results of measurement in the real tunnels. The results also show that tunnel noises are proportional to the train velocity entering the tunnel.

• Proceedings of the KIEE Conference
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• 2002.07c
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• pp.1494-1496
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• 2002

내열 충격성 및 적외선 투과를 갖는 LAS($Li_2O-Al_2O_3-SiO_2$)계 글라스세라믹스를 제조하였다. 본 연구에서는 LAS계에 $TiO_2$를 핵형성제로, 점도를 감소시키기 위해 $P_2O_5$를 첨가하여 유리를 제조한 후, 글라스세라믹 결정상을 석출시켰다. 석출된 주 결정상은 ${\beta}$-eucryptite(SS)이었으며, 열팽창 계수가 거의 제로에 가까운 값을 얻었다. 또한 선택적인 스펙트럼의 흡수를 위한 color dopants에 대한 기초 자료 등이 조사되었다.

• The Journal of the Korean life insurance medical association
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• v.3 no.1
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• pp.90-102
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• 1986

The gallbladder is a pear-shaped, thin walled sac located on the inferior surface of the liver between the right and quadrate lobe, in a recess called fossa vesicae felleae. It is 7.5cm-12.5 cm in length, 3.5 cm in the largest width, and has a volume of about 45 ml with a remarkable capacity for expansion. There are many kinds of diagnostic methods to evaluate diseases of biliary tract including gallbladder-Plain abdomen, Oral cholecystography. Intravenous cholangiography, Percutaneous transhepatic cholangiography(PTC), Endoscopic retrograde cholangiography(ERCP), Operative or T-tube cholangiography, Ultrasonography, Radioisotope study, Computed tomography, and Angiography. Especially, ultrasonography is the most effective and noninvasive study in these days. Plain abdomen, oral cholecystography, intravenous cholangiography, and ultrasonography have been performed in our clinic. Methods and findings of above mentioned study are discussed with consideration of references.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1994.10a
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• pp.389-394
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• 1994

The lattice filter formed transfer function has the advantage of computer simulation in the analysis of muffler. The transfer function is derived by using z-transformation for perforated elements in through-flow, cross-flow and reverse-flow type. A computer program for the prediction of the performance of automotive mufflers is developed using the transfer functions for uniform tube, open termination, expansion element, perforated elements, etc. The analytical results are verified by comparing with the experimental results for the transmission loss of a muffer. The effect of geometric configuration change of the muffler was invesigated in order to improve the performance of noise attenuation.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.20 no.2
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• pp.169-173
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• 2011

Crash box is introduced to vehicle design to improve the impact performance and reduce the damage of vehicle body at impact speed. The crash box behind bumper can absorb impact energy effectively to improve vehicle safety. Repair cost at collision accident can be cut down by use of this box. The configuration of car body must be designed by considering the characteristic of material due to the deformation of car body happened at impact. Many papers have been published about material of crash box all over the world. The study of crash box with tube expansion type has been going on Korea. This study is done by the simulation analysis about front collisions against 5 kinds of aluminum crash boxes with the basic structure of square section.

• Elastomers and Composites
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• v.51 no.4
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• pp.280-285
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• 2016

The purpose of this study is to get optimum design and operation conditions of the heating rubber roller for laminating process. The cause of performance degradation of heating rubber roller is delamination of rubber on metal tube, rubber aging due to high temperature. We measured the material properties of thermal expansion, thermal conductivity, specific heat and density and analyzed thermal distributions of rubber layer using finite element method. As a result of heat/flow analysis, the density distribution of heating coil must shorten the stabilization time by reducing the temperature deviation on the length direction at the temperature rising section after increasing the density of the area contacting with the laminate film at the center part which is an opposite of the current composition while enabling to maintain the temperature of heater to be consistent while maintaining the temperature deviation to be low when heat loss is created. Finally, we determined optimum heating method of heating rubber roller.

• Proceedings of the KSR Conference
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• 1998.05a
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• pp.377-384
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• 1998

The crushable front part of the conventional TGV is composed of 3 energy absorption zones; retractable coupler, protective headstock and honeycomb structure. This frontal part must absorb about 80% of the energy that should be done in a cra shworthy design. The conventional TGV can absorb 2MJ impact energy by the frontal end, but 5MJ is the design target for energy absorption in the next generation TGV. To accomplish this design goal, a new concept of design is necessary for energy absorbing components. In this paper, the design concept of the tube expansion energy absorber will be proposed and analyzed. The crash analysis of the energy absorber are performed by comparing the value of the theoretical equation wi th the simulation calculated from the commercial nonlinear FE-Code ‘PAM-CRASH’ S/W.

• Journal of the Korean Chemical Society
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• v.6 no.1
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• pp.54-60
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• 1962

The water gas shift conversion catalyst prepared by the American Cyanamide Co. was subjected to fluidization in a 2-in. Pyrex glass tube to obtain the basic fluidization characteristic data. The size of the catalyst charged ranged from 70 to 120 meshes and it was supported on a single layer 300-mesh wire gauze through which the fluidizing medium, the air, was passed. Following are some data and facts found by the authors: (1) The catalyst particles were porous, and their surfaces were trough and irregular. (2) The average effective particle density and the average shape factor of these particles were 152.2 lb/$ft^3$ and 0.865 respectively. (3) As the particle diameter of the catalyst increased, the minimum fluid voidage of the bed decreased slightly. (4) Just before the incipient fluidization, pressure drop suddenly fell and the bed expanded simultaneously. (5) After fluidization set in, the expansion characteristics of the catalyst bed were similar to those of sand and glass beads except intense bubbling in the catalyst bed.