• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1997.03a
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• pp.55-58
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• 1997

In automotive industries, stamping of laser-welded blank gives many merits which brings about dimensional accuracy, strong body assembly and high productivity. However the welding of blanks with different thickness or/and different strength materials introduces many challenging formability problems for process development and tool design. In this paper, the deformation characteristics for deep drawing process of laser-welded blank with different thickness sheets are investigated by experiment and FEM simulation. And also the optimal location of weld line in laser-welded blank with different thickness sheets is calculated to compensate for the movement of weld line on deep drawing process. In addition, the effect of location of weld line is clarified using FEM simulation.

• Transactions of Materials Processing
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• v.7 no.6
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• pp.519-529
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• 1998

In automotive industries the stamping of laser-welded blank gives many merits which bring about dimensional accuracy, strong body assembly and high productivity. However the welding of blanks with different thickness or/and different strength materials introduces many challenging formability problems for process development and tool design. in this paper the deformation characteristics for deep drawing process of laser-welded blank with different thickness sheets are investigated by experiment as well as by FEM simulation. The blank holding force ratio to avoid the movement of weld line was suggested and compared with the experimental result for cylindrical and rectangular cup drawing process. The optimal location of weld line in laser-welded blank with different thickness sheets is calculated to compensate for the movement of weld line on deep drawing process. In addition the effect of location of weld line on formability is clarified using FEM simulation.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.55 no.10
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• pp.492-498
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• 2006

A novel surface plasmon resonance(SPR) multisensing method, which does not require imaging apparatus such as CCD, has been proposed and implemented experimentally. The proposed method is based on the multichannel SPR and the separation of signals by use of additional layers whose thickness is controlled. SPR signals are influenced by the thickness of sensing layer as well as the optical condition of sensing surface. As the SPR signals from different ligands are usually positioned closely, the reflected light from sensing surface does not provide us with the clear differences of resonance signal depending on the kinds of ligands. It was found from our experiments that SPR signals from each ligand that is located on the additional layer with different thickness can be separated clearly enough to identify various signals from different ligands. Proposed method with theoretical design and simulation has been verified experimentally by using $SiO_2$ thin film layer as additional layer.

• Nuclear Engineering and Technology
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• v.32 no.5
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• pp.457-464
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• 2000

In this paper, we describe the results of various calculations performed for a design of the thickness gauges that use the gamma-ray backscattering method. The radiation source is assumed to be the $_{24}$1Am(60keV gamma-ray) and the detector is a single crystal scintillator in a cylindrical form. The source is located at the center of the detector with the collimator of a cylindrical shape. First, when gamma-rays are incident on a material with a constant angle, we compute the variations of the spectrum for the photons scattered into different angular intervals. Next, we compute for an optimal size for the collimator cylinder for a fixed detector size and an optimal distance from the detector to the material. Finally, we compute the number of observed photons for different thickness of two different materials, a plastic film and an Al foil.

• PNF and Movement
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• v.18 no.3
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• pp.415-424
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• 2020

Purpose: This study aimed to compare changes in abdominal muscle thickness in different standing postures with a handheld load between subjects with and without chronic low back pain (CLBP). Methods: Twenty subjects with CLBP and 20 controls participated in this study. Ultrasound imaging was used to assess the changes in the thickness of the transverse abdominis (TrA), internal oblique (IO), and external oblique (EO) muscles. Muscle thickness in three different standing postures (standing at rest, standing with loads, standing with lifting loads) was compared with the muscle thickness at rest in the supine position and was expressed as a percentage of change in the thickness of the muscle. Results: While standing with loads, the change in IO muscle thickness in the CLBP patients increased more significantly than in the pain-free controls (p < 0.05). The standing with lifting loads posture showed a significant increase in the change in thickness of the TrA compared with the standing with loads posture (p < 0.05). In addition, the standing with lifting loads posture showed a significant decrease in the change in the thickness of the EO when compared with the standing with loads posture (p < 0.05). Conclusion: The automatic activity of the IO muscle in subjects with CLBP increased more than that of the pain-free controls in the standing with loads posture. These findings suggest that IO muscle function may be altered in those with CLBP while standing with loads. Additionally, TrA the activation level was found to be associated with increased postural demand caused by an elevated center of mass.

• Journal of Mechanical Science and Technology
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• v.19 no.9
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• pp.1753-1760
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• 2005

The pseudo spectral method is applied to the free vibration analysis of double-span Timoshenko beams. The analysis is based on the Chebyshev polynomials. Each section of the double-span beam has its own basis functions, and the continuity conditions at the intermediate support as well as the boundary conditions are treated separately as the constraints of the basis functions. Natural frequencies are provided for different thickness-to-length ratios and for different span ratios, which agree with those of Euler-Bernoulli beams when the thickness-to-length ratio is small but deviate considerably as the thickness-to-length ratio grows larger.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.10b
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• pp.773-778
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• 1998

For imaging of concrete specimens using radar, the principles of radar, microwave, and the electromagnetic properties of concrete are discussed. Experimental data obtained from radar measurement of concrete specimens with no steel bars at three different frequency bandwidths of 2~3.4 GHz, 3.4~5.8 GHz and 8~12 GHz are processed to determine the thickness of the specimens. A signal processing scheme has been implemented to visualize the concrete specimens. The purpose of this study is to determine particular frequency range appropriate for measuring the thickness of concrete specimens using radar.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.15 no.5
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• pp.372-381
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• 2003

This study aims to find out the optimized insulation thickness of refrigerated warehouse with different envelope structures (RC and PC wall) and insulation materials (urethane and icynene). Each of them is compared according to the thickness of insulation (100, 150, 200 mm/50 or 250 mm) and the temperature of cold storage room (0, -6, -15$^{\circ}C$). As results, it is proved to have the best economical efficiency in life cycle cost when PC wall with thickness of 100 mm (0 and -6$^{\circ}C$) and 150 m (-15$^{\circ}C$) urethane, respectively, are applied.

• Journal of the Korea Furniture Society
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• v.17 no.4
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• pp.109-114
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• 2006

An investigation was carried out for the annual ring width, longitudinal tracheid diameter and wall thickness in different tree heights for Pinus koraiensis Sieb. et. Zucc. The annual ring width increased along with the tree height, however the tracheid diameter and wall thickness decreased with the tree height. Tracheid wall thickness was found the thickest at 2.0m from the above ground samples and it increased gradually from pith to bark. Radial tracheid diameter was found to be larger than that of tangential tracheid diameter in earlywood. But, it was found to be the opposite in latewood. In earlywood, the average values of tracheid wall thickness was found the range of $2.1-3.0{\mu}m$, whereas, in latewood, it was $2.4-4.2{\mu}m$.

• The Journal of Engineering Research
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• v.6 no.2
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• pp.33-38
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• 2004

To investigate the reliability of the MTJs on the roughness of insulating tunnel barrier, we prepared two MTJs with the different uniformity of barrier thickness. Namely, the one has uniform insulating barrier thickness; the other has non-uniform insulating barrier thickness as compared to different thing. As to depositing amorphous layer CoZrNb under the pinning layer IrMn, we achieved MTJ with uniform barrier thickness. Toinvestigate the reliability of the MTJs dependent on the bottom electrode, time-dependent dielectric breakdown (TDDB) measurements were carried out under constant voltage stress. The Weibull fit of out data shows clearly that $t_{BD}$ scales with the thickness uniformity of MTJs tunnel barrier. Assuming a linear dependence of log($t_{BD}$) on stress voltages, we obtained the lifetime of $10^4$years at a operating voltage of 0.4 V at MTJs comprising CoNbZr layers. This study shows that the reliabilityof new MTJs structure was improved due to the ultra smooth barrier, because the surface roughness of the bottom electrode influenced the uniformity of tunnel barrier.