• Journal of the Korean Society for Advanced Composite Structures
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• v.6 no.2
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• pp.52-62
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• 2015

This study aims at developing a new seismic resistant method by using precast concrete wall panels for existing low-rise, reinforced concrete beam-column buildings such as school buildings. Three quasi-static hysteresis loading tests were performed on one unreinforced beam-column specimen and two reinforced specimens with U-type precast wall panels. Top shear connection of the PC panel was required to show the composite strength of RC column and PC wall panel. However, the strength of the connection did not influence directly on the ultimate loading capacities of the specimens in the positive loading because the loaded RC column push the side of PC wall panel and it moved horizontally before the shear connector receive the concentrated shear force in the positive loading process. Under the positive loading sequence(push loading), the reinforced concrete column and PC panel showed flexural strength which is larger than 97% of the composite section because of the rigid binding at the top of precast panel. Similar load-deformation relationship and ultimated horizontal load capacities were shown in the test of PR1-LA and PR1-LP specimens because they have same section dimension and detail at the flexural critical section. An average of 4.7 times increase in the positive maximum loading(average 967kN) and 2.7 times increase in the negative maximum loading(average 592.5kN) had resulted from the test of seismic resistant specimens with anchored and welded steel plate connections than that of unreinforced beam-column specimen. The maximum drift ratios were also shown between 1.0% and 1.4%.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2011.06a
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• pp.1221-1222
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• 2011

• 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.

• Proceedings of the Korea Concrete Institute Conference
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• 2010.05a
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• pp.95-96
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• 2010

This paper presents the crack control of reinforcement concrete composite slabs which were produced with the extruded ECC panel. Cracking control performance was evaluated based on the flexural tests on real scale one-way slabs manufactured with or without ECC panel.

• Steel and Composite Structures
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• v.19 no.6
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• pp.1333-1354
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• 2015

A higher order analytical solution for static analysis of a truncated conical composite sandwich panel subjected to different loading conditions was presented in this paper which was based on a new improved higher order sandwich panel theory. Bending analysis of sandwich structures with flexible cores subjected to concentrated load, uniform distributed load on a patch, harmonic and uniform distributed loads on the top and/or bottom face sheet of the sandwich structure was also investigated. For the first time, bending analysis of truncated conical composite sandwich panels with flexible cores was performed. The governing equations were derived by principle of minimum potential energy. The first order shear deformation theory was used for the composite face sheets and for the core while assuming a polynomial description of the displacement fields. Also, the in-plane hoop stresses of the core were considered. In order to assure accuracy of the present formulations, convergence of the results was examined. Effects of types of boundary conditions, types of applied loads, conical angles and fiber angles on bending analysis of truncated conical composite sandwich panels were studied. As, there is no research on higher order bending analysis of conical sandwich panels with flexible cores, the results were validated by ABAQUS FE code. The present approach can be linked with the standard optimization programs and it can be used in the iteration process of the structural optimization. The proposed approach facilitates investigation of the effect of physical and geometrical parameters on the bending response of sandwich composite structures.

• Composites Research
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• v.14 no.6
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• pp.1-8
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• 2001

In this paper, the sandwich panel composites consisting of core material and face sheet were studied to evaluate the mechanical properties, noise level and fire resistance including flammability, smoke, and toxicity. Four types of sandwich panel were prepared using various kinds of panel and honeycomb materials. It was observed that Al honeycomb/Al skin composite materials had the excellent flatwise tensile strength and edgewise compressive strength compared with other types of composites. The flatwise compressive strength and flexural strength of Nomex honeycomb/Al skin composite were higher than those of other composites. PMI form/Al skin composite showed the higher core shear strength and facing bending strength. From the experimental results of flame resistance tests, it can be said that the phenol based skin composite has the excellent flame retardation properties, which are similar to those of the commercial skin composites.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.22 no.3
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• pp.414-420
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• 2013

Research on decreasing the weight of composite sandwich panels is in progress. This paper reports the experimental results for the mechanical behavior of a composite sandwich panel. The skins of sandwich panels were made of glass fiber sheets and plywood matrix composites. Their interior layers consisted of glass fiber pultrusion pipes and gold foam. Experimental tests were performed to obtain the mechanical properties and complex mechanical behavior. Before fatigue tests, tensile tests and 3-point bending tests were carried out to obtain the optimal design and determine their strength and failure mechanisms in the flat-wise position. After the static test, a fatigue test were conducted at a load frequency of 5 Hz, stress ratio (R) of 0.1, and endurance limit for the S-N curve. It showed that the failure modes were related to both the core design and skin failure.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.4
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• pp.958-966
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• 1994

The postbuckling compressive strengths of $[0/90/\pm\theta]_s$ composite laminated cylindrical panels with various fiber angles and width-to-length ratios are characterized by the nonlinear finite element method. For the iteration and load-increment along the postbuckling equilibrium path a modified arc-length method in which the effect of failure can be considered is introduced. In the progressive failure analysis the maximum stress criterion and complete unloading model are used. Present finite element results show good agreement with experiments for $[0_3/90]_s$ cylindrical panel and $[0/\pm45/90/]_s$ plate. The postbuckling compressive strength of $[0/90/\pm\theta]_s$ composite laminated cylindrical panel is independent of the initial buckling stress but high in the panel with large value of the bending stiffness in axial direction. In the several cylindrical panels, it is observed that the prebuckling compressive failures occur and result into the collapse before the buckling.

• Journal of the Korean Institute of Educational Facilities
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• v.13 no.1
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• pp.17-25
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• 2006

Elementary school classroom designs have been developed toward open education system to provide students diverse and improved educational environments since the early of 1990 in Korea. Unfortunately, the quality of music room has not still shown dramatic improvements due to the lack of the acoustical knowledges of architects. This report aims to investigate typical acoustic quality of previous or current music room of elementary schools and show new acoustic treatment technologies to improve the room acoustic of music room by adapting composite perforated panel system and diffusion technology. The music room at Daihyun Elementary school in Yongin was chosen as a case study of this report. The music room was measured to be analyzed using field measurements and the acoustical specifications of composite perforated panel systems and kinds of diffusors were set. Acoustic measurements were performed after the renovation to show the differences between previous room acoustic and after the acoustic renovations. As the result, the case study has shown that the new composite perforated panel systems and diffusion surfaces lowered reverberation time at proper level along with improving the clarity of music, RASTI, and spatial impressions. Also, acoustic interferences such as comb filtering and flutter echoes have been controlled dramatically by diffusive surfaces. The study shows music rooms in elementary schools, middle and high schools can be improved by adapting composite perforated panel systems and diffusors.