• Structural Engineering and Mechanics
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• v.68 no.6
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• pp.721-733
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• 2018

The modal frequency responses of functionally graded (FG) sandwich doubly curved shell panels are investigated using a higher-order finite element formulation. The system of equations of the panel structure derived using Hamilton's principle for the evaluation of natural frequencies. The present shell panel model is discretised using the isoparametric Lagrangian element (nine nodes and nine degrees of freedom per node). An in-house MATLAB code is prepared using higher-order kinematics in association with the finite element scheme for the calculation of modal values. The stability of the opted numerical vibration frequency solutions for the various shell geometries i.e., single and doubly curved FG sandwich structure are proven via the convergence test. Further, close conformance of the finite element frequency solutions for the FG sandwich structures is found when compared with the published theoretical predictions (numerical, analytical and 3D elasticity solutions). Subsequently, appropriate numerical examples are solved pertaining to various design factors (curvature ratio, core-face thickness ratio, aspect ratio, support conditions, power-law index and sandwich symmetry type) those have the significant influence on the free vibration modal data of the FG sandwich curved structure.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.125-128
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• 2003

In machine tool design, fast traversing cannot be achieved without reducing mass of the moving part. Honeycomb sandwich panel is extremely lightweight, and relatively rigid at the same time. We can reduce much weight when we selectively utilize honeycomb sandwich panels as stiffeners on machine tool structures. Feasibility of reducing weight is studied using a beam structure with both ends fixed.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.951-955
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• 2007

Recently, drywall's demand is increasing by interest about spread of remodeling house and separated wall structure. This research evaluated panel's SRI and found out panel properties using material of small size. Conclusion of this research is as following. First, we confirmed the effectiveness of small-scale material. Measuring results appeared equally about 400 ${\sim}$ 500 Hz that is fc frequency. Second,, it is no big difference in SRI that use CRC or magnesium board that is used for protection of panel surface. Third, it is compared SRI by used junction to make wall that become disjointing assembly. By the result, sealed wall secures resemblant SRI performance almost with normal wall. Therefore, using joint materials and sealing junction became wall that is detached with high SRI.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.05a
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• pp.56-60
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• 2007

Nowadays shear wall structural system is gradually changing to framed structure. For this reason, lightweight panel is increasingly being used as separating walls. One of design methods to obtain high transmission loss is double panel. To predict the acoustic performance of double panel, prediction of transmission loss of single panel must be performed, previously. In this study, the predicted values for four single panels were compared with the measured values. The result shows the arithmetical average deviations(100Hz to 3150Hz) between the predicted and measured transmission loss were in range between 1.1dB and 3.9dB. The predicted values were generally lower than measured values above critical frequency. The single-number quantities, $R_W+C$, were predicted in range between 36dB to 38dB, and the differences of single-number quantities between the predicted and measured value were within 1dB.

• Proceedings of the KSR Conference
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• 2005.05a
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• pp.251-256
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• 2005

This study was performed the heat transportation ratio of three types of the following sandwich panel by KS F 2278(2003) ; Type ${\sharp}1$ : Carbon/epoxy Aluminum Honeycomb and Balsa Core Sandwich Panel(Thickness : 37mm), Type ${\sharp}2$ : Carbon/epoxy Aluminum Honeycomb Core Sandwich Panel(Thickness : 57mm), and Type ${\sharp}3$ : Carbon/epoxy Aluminum Honeycomb Core Sandwich Panel(Thickness : 37mm). Also was performed the heat transportation of next three types of the following sandwich panel by KS F2277(2002) ; Type ${\sharp}4$ and ${\sharp}5$ : 27mm, and 35mm thick-Aluminum Honeycomb Sandwich Panels, and Type ${\sharp}6$ : 27mm thick-Foaming Aluminum Sandwich Panel. It is the larger area between the skin and core, the heat transportation ratio is the higher, and when it is composed of the hybrid composite structure, good insulation property was shown.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.06a
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• pp.972-977
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• 2000

One of the major differences of Korean residential building compared with other countries is a rigid diaphragm of a floor due to the panel heating system. An increment of a gravity floor load might cause vibration problem when the composite floor system is introduced to the panel heating system. Since the noise criteria of a residential building is lower than that of an office building, the development of a noise absorbing system should be preceded. The response evaluation was performed for the finished floor, that is with panel heating and noise absorbing system. The natural frequency was obtained both from an experimental study and an analytical study. An appropriate vibration condition of a floor with panel heating and noise absorbing systems was evaluated from this study.

• 한국정보디스플레이학회:학술대회논문집
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• 2000.01a
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• pp.11-12
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• 2000

An 18.1" Thin Film Transistor Liquid Crystal Display (TFT LCD) monitor adopting high brightness In Plane Switching (IPS) technology was realized. While conventional IPS structure used a Chromium (Cr) and Molybdenum (Mo) for a drain electrode, Indium Tin Oxide (ITO) was proposed and verified in this paper. Black sticky micropeal spacers were introduced for the reduction of light scattering phenomena, which was observed at dark room with the conventional micropeal spacers. With the proposed method, more than 10 % aperture ratio was increased and the excellent image quality was obtained.

• Proceedings of the KSR Conference
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• 2009.05a
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• pp.1088-1091
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• 2009

In a tilting train, aluminium honeycomb composite panel is used for the high speed and light weight. Side wall of the tilting train includes the composite panel of carbon fiber, aluminium honeycomb and epoxy fiber as a main structure. In this study, we measure the transmission loss (TL) of the honeycomb composite panel and analyse the sound insulation performance by using the orthotropic plate model. We investigate experimentally how the air gap, plywood and glass wool improve the sound insulation performance of the composite panel. The purpose of the study is to provide practical information for the improvement of TL of the honeycomb composite panel used for the tilting train.

• Journal of KSNVE
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• v.9 no.2
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• pp.248-257
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• 1999

This paper presents the model updating of an equipment panel by using modal test and sensitivity analysis. The equipment panel is one of the major structures of communication satelite, on which broadcasting and communication equipments are mounted. For high rigidity and light weight, the panel was designed as an aluminum honeycomb sandwich panel. In addition, heat pipes were embedded in the panel for thermal control. It is essential to improve the finite element model of a spacecraft structure by using modal test in order to verify that the satellite is designed and fabricated with adequate margin under launch environment. In this paper, Young's modulus of aluminumfacesheet was selected as a modified parameter in the sensitivity analysis. The effect of boundary conditions on model improvement was also investigated.

• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.17-19
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• 2008

An advanced TFT-LCD structure was proposed to increase aperture ratio (AR). In this structure, metal layers formed below the data lines are used as light-blocking layers, achieving higher AR ratio than that of a conventional structure. Since average misalignment between the metal light-blocking layers and pixel electrodes is smaller than that of black matrixes on color filter glass, substantially less light-blocking areas are needed to achieve misalignment margin. The AR of the LCD panel fabricated by using proposed structure was enhanced by 18.7 % over that of the conventionally structured panel.