• Journal of the korean Society of Automotive Engineers
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• v.14 no.1
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• pp.25-37
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• 1992

Interior noise in a car is known to have an important influence on product acceptability. This noise is closely correlated with structural-acoustic vibration. When considering noise problem, the structural-acoustic relation of a vehicle cabin model needs to be identified. However, it is very difficult to get the modal parameters of this kind of cabin structure composed of thin plates: because it not only can be excited by the acoustic vibration of cavity, but also tends to have decoupling effects of one plate from another. In order to obtain modal parameters more precisely, various excitation techniques, i.e. impact, pure random, burst random, and swept sine testing are applied for the first step. In the case of the cabin model, impact and swept sine testing show good results. Next, the determination of the excitation point by trial- and-error and the accurate measurements of FRF's are performed with these methods. The modal parameter extraction is carried out for the final step. This paper proposes a new approach to find the modal parameters more reliably in the case of high decoupling effects. That is, the convergence of MIF and MCF in each panel, which provide some criteria for the validity of the obtained modal parameters, is observed. And from those results, the pretty accurate modal parameters can be determined. A comparative assessment between the modal testing and the FEM is also performed.

• Journal of Korea Foundry Society
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• v.14 no.1
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• pp.45-51
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• 1994

The possibility of using bulk talc as molding material was reviewed and tested with the measurement of thermal properties and computer simulations. The measured thermal conductivity and heat diffusivity($k{\rho}c$) of talc were $2.4W/m^{\circ}C$ and $6.6{\times}10^6J^2/m^4^{\circ}C^2s$, respectively. Thermal properties of talc could be ranked between those of sand mold and iron mold. Talc transforms into cristobalite and enstatite at $910^{\circ}C$, During the transformation volume and structure change, cracks appear on the surface and distortion occurs. Therefore talc can be used for molding material below $910^{\circ}C$ if carefully treated. Computer simulation was carried out to test whether talc insert could promote directional solidification in sand mold and iron mold. In sand mold, it was possible to achieve directional solidification of thin plate casting with the length to thickness ratio of 15, if both iron insert and talc insert were used. In iron mold, it was possible to achieve directional solidification only with talc insert.

• Journal of Sensor Science and Technology
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• v.10 no.1
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• pp.80-85
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• 2001

$Hg_{1-x}Cd_xTe$(MCT) thin films were grown onto ITO glass and titanium plate by stationary cathodic electrodeposition in aqueous solution contained $CdSO_4$, $TeO_2$, and $HgCl_2$. During deposition two main fabrication parameters were taken into account deposition potential and growth temperature. MCT films deposited by varying two parameters were studied by X-ray diffraction, electron probe micro analyser(EPMA) and scanning electron microscope measurements. It was shown by XRD and EPMA measurements that the structure of MCT films was zinc blonde and the composition of MCT films can be controlled with the deposition potential.

• Journal of the Korean Society of Clothing and Textiles
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• v.15 no.4 s.40
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• pp.373-380
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• 1991

In the previous paper, we already discussed about the factor effected upon the initial maximum value of heat flux ($q_{max}$). Thermal conductivity, thermal transmittance and surface air cavity of wool fabrics were examind and their correlation to the $q_{max}$ was also studied In this study, the other factor was examined which had on effect upon the qmaf of an objective measure of warm/cool feeling. It was studied that the qmax correlated to the surface sturucture parameters (compression, friction, smoothness, roughness, thickness and weight). It was concerned to the degree of warm/cool feeling when we touched hand on fabrics. We selected twenty sorts of pure wool woven fabrics for men's fall-winter cloth (all Wool). The conclusions are as follow; 1. There was a good correlation between the $q_{max}$ and the compression property. 2. The surface structure parameters, smoothness and roughness, made various effects on the $q_{max}$, when the samples touched on a thin copper plate. So, there was not a certain correla-tion to the $q_{max}$.

• Proceedings of the SAREK Conference
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• 2008.11a
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• pp.170-174
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• 2008

Recently, a problem related to the thermal management in portable electronic and telecommunication devices is becoming issued. That is due to the trend of slimness of the devices, so it is not easy to find the optimal thermal management technology for the devices. From now on, a pressed circular type cooling device has been mainly used, however the cooling device with thin thickness is becoming needed by the inner space constraint. In the present study, the silicon and metal flat plate type cooling device with the separated vapor and liquid flow path was designed and fabricated. Through the experimental study, the normal isothermal characteristic by vapor-liquid phase change was confirmed and the cooling device with 70mm of total length showed 6.8W of the heat transfer rate within the range of $4{\sim}5^{\circ}C$/W of thermal resistance. In the meantime, the metal cooling device was developed for commercialization. The device was designed to have all structures of evaporator, vapor flow path, liquid flow path and condenser in one plate. And an envelope of that could be completed by combining the two plates of same structure and size. And the simplicity of fabrication process and reduction of manufacturing cost could be accomplished by using the stamping technology for fabricating large flow paths relatively. In the future, it will be possible to develop the commercialized cooling device by revising the fabrication process and enhancing the thermal performance of that.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.8
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• pp.1035-1041
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• 2013

To evaluate the structural integrity and dynamic characteristic of the knuckle part of a KTX anti-roll bar, an experimental and a numerical approach were used in this study. In the experimental approach, the acceleration and strain data for the knuckle parts of the KTX and KTX-SANCHUN anti-roll bar were respectively measured to evaluate and compare its structural dynamic characteristics under the operating environments of the Honam line. In the numerical approach, the evaluation of its structural integrity was conducted using LS-DYNA 3D, and then, the reliability of the finite element model used was ensured by a comparative evaluation with the experiment. The numerical results showed that the stress and velocity field of the knuckle part composed of a layered structure of a thin steel plate and rubber were more moderate than those of the knuckle part made of only a thick steel block owing to the reduction of relative contact between the knuckle and the connecting rod. It was found that the knuckle part made of a thin steel plate and rubber was recommended as the best solution to improve its structural integrity resulting from the elastic behavior of the KTX anti-roll bar being enabled under a repeating external force.

• Journal of Korean Society of Steel Construction
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• v.16 no.5 s.72
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• pp.555-564
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• 2004

Steel materials, which are normally used in bridge structures, are prone to corrosion and have thin plate structures. Steel bridges that have been damaged through increased vehicle load and corrosion are frequently expected to be strengthened. Repair or strengthening methods generally include cutting, bolting, and welding. The basic characteristics of stress and deformation behavior generated by cutting and welding in the course of the repair work, however, are not yet understood. It is difficult to say whether the safety of the structure after welding conforms with existing safety evaluation methods.Therefore, to gain confidence in the material and to guarantee the safety of the structure after welding, the stress generated by heat, through welding and cutting, was generalized. The effect of additional loads with respect to stress generated by heat was also investigated.

• Earthquakes and Structures
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• v.26 no.3
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• pp.203-218
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• 2024

Beam-column joints in the frame structure are at high risk of brittle shear failure which would lead to significant residual deformation and even the collapse of the structure during an earthquake. In order to improve the damage issue and enhance the recoverability of the beam-column joints, a sector lead rubber damper (SLRD) has been developed. The SLRD can increase the bearing capacity and energy dissipation capacity, and also demonstrating recoverability of seismic performance following cyclic loading. In this paper, the hysteretic behavior of SLRD was experimentally investigated in terms of the regular hysteretic behavior, large deformation behavior and fatigue behavior. Furthermore, a parametric analysis was performed to study the influence of the primary design parameters on the hysteretic behavior of SLRD. The results show that SLRD resist the exerted loading through the shear capacity of both rubber parts coupled with the lead cores in the pre-yielding stage of lead cores. In the post-yielding phase, it is only the rubber parts of the SLRD that provide the shear capacity while the lead cores primarily dissipate the energy through shear deformation. The SLRD possesses a robust capacity for large deformation and can sustain hysteretic behavior when subjected to a loading rotation angle of 1/7 (equivalent to 200% shear strain of the rubber component). Furthermore, it demonstrates excellent fatigue resistance, with a degradation of critical behavior indices by no more than 15% in comparison to initial values even after 30 cycles. As for the designing practice of SLRD, it is recommended to adopt the double lead core scheme, along with a rubber material having the lowest possible shear modulus while meeting the desired bearing capacity and a thickness ratio of 0.4 to 0.5 for the thin steel plate.

• Applied Chemistry for Engineering
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• v.18 no.3
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• pp.262-266
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• 2007

The effect of the presence of magnesium ions in the preparation of calcium phosphate (CP) thin films on the physicochemical and biological properties of the films has been investigated in this study. Five different surfaces were used and the culture plate (CTL) and CP film prepared in the absence of magnesium (CaP) were used for the comparison. Three different films were prepared at different magnesium concentrations. CP films prepared at the Mg concentrations of 0.1, 1, and 10 mM were designated as CaPL, CaPM, and CaPH, respectively. The observation of surface morphology of the CP films using scanning electron microscopy (SEM) displayed that the presence of magnesium affected considerably the morphology of the films including a decrease of surface porosity. X-ray diffraction (XRD) analysis for the determination of the crystallinity of the CP films showed that the structure of the films was amorphous. Examination using X-ray photoelectron spectroscopy (XPS) confirmed the prepared films consisted of calcium, phophorus, and magnesium. Cell adhesion assays elucidated that cell adhered less as the magnesium concentration increased. However, cell proliferation assays demonstrated that the cells proliferated more actively on the films prepared at the higher magnesium concentration. These results suggest that the presence of magnesium may promote the biocompatibility of CP films.

• Journal of the Korean Vacuum Society
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• v.22 no.5
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• pp.250-256
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• 2013

It is described that the proton beam induces micro-size defects and electronic deep levels in luminescence Thin Film. Coincidence Doppler Broadening Positron Annihilation Spectroscopy (CDBPAS) and Positron lifetime Spectroscopy were applied to study of characteristics of a poly crystal samples. In this investigation the numerical analysis of the Doppler spectra was employed to the determination of the shape parameter, S-parameter value. The samples were exposed by 3.0 MeV proton beams with the intensities ranging between 0 to ${\sim}10^{14}$ particles. The S-parameter values decreased as increased the proton beam, that indicates the protons trapped in vacancies. Lifetime ${\tau}_1$ shows that positrons are trapped in mono vacancies. Lifetime ${\tau}_2$ is not changed according to proton irradiation that indicate the cluster vacancies of the grain structure.