• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1998.11a
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• pp.211-214
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• 1998

DC breakdown characteristics and formation of space charge at the interfaces of crosslinked polyethylene (XLPE) /ethylene propylene diene terpolymer (EPDM) laminates were studied. Effects of silicone grease and some chemicals such as crosslinking coagent on the interfacial charge were also studied. Interfacial charge develops at the interface of XLPE/EPDM laminates, which changes depending on heat treatment conditions and types of chemicals coated at the interface. Some chemicals such as maleic anhydride reduce the accumulation of interfacial charge in the XLPE/EPDM laminates. Breakdown strength of EPDM/XLPE laminate through the interface was highest when silicone oil was pasted in the interfaces. Interfacial breakdown strength decreased with the increase of MAH content.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05a
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• pp.258-261
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• 2006

This study investigates the flexural behavior and strengthening performance of RC beams with unbonded prestressing CFRP laminates through static bending tests. The aluminum anchorage system has been developed in tins study and successfully applied to the test specimens. The prestressing level of CFRP laminatehas was 0 %, 20 %, 30% and 50 % of its tensile strength. Experimental results revealed that RC beams with unbonded prestressing CFRP laminates showed increased crack load and yield load according to the level of prestress. It has also been observed that the length of the CFRP laminates does not have significant effect on the maximum load.

• Proceedings of the KIEE Conference
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• 2001.07c
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• pp.1637-1639
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• 2001

Air arc interruption used in low rated voltage breaker, ACB and MCCB, have used the arc chamber composed of metal plates and insulating laminates which supposed these mechanically. and geometry and materials of arc chamber are very different by breaker manufacturer. These breakers have required to be smaller and to interrupt higher current by user. therefore the arc chamber geometry and material in breaker have been small, complex and various. The purpose of this study is to examine the effects of insulating laminates and contact materials on air arc interruption. Contacts were surrounded by a rectangle chamber of insulating laminates. Contact concoctions were composed of AgW, AgCdO that have used in low rated voltage breaker, and insulating laminates were polyester, epoxy. We found strong dependance of arc voltage on insulating material. The ablated vapor on polyester increased arc voltage that was useful in air arc interruption.

• Proceedings of the KIEE Conference
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• 1998.07d
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• pp.1273-1275
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• 1998

The main faults at cable joint are mainly originate from double layered structure, which is composed of different kinds of materials such as XLPE/EPDM laminatest. In this paper, to investigate the effect of interfacial condition and coagents on dielectric strength of XLPE/EPDM, we prepared XLPE/grease/EPDM, XLPE/grease + coagent/EPDM laminates. Dielectric strength of the XLPE/EPDM laminates pasted with the grease compounded crosslinking coagent (TMPTA, TMPTMA) is higher than that of the laminates paseted with the grease without coagent.

• Journal of the Korean Ceramic Society
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• v.29 no.3
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• pp.241-251
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• 1992

The effects of slip composition and processing conditions on the fabrication of ceramic heat exchanger cores by doctor blade process were investigated. Since the effects of those two variables were inter-dependent, the effects of binder system, binder plus plasticizer, were extensively studied for a limited range of processing conditions and a pre-determined ceramic composition. The content of binder system and the ratio of binder to plasticizer were identified as main variables to affect densities and mechanical properties of green sheets, compressive properties and bond strengths of laminates, and shrinkages and their anisotropy of sintered laminates. However, sintered densities and water absorptions of laminates were not influenced by either the content of binder system or the ratio of binder to plasticizer, when the debinded laminates had a relatively high density (relative density of >55% in this study).

• Journal of Ocean Engineering and Technology
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• v.16 no.6
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• pp.55-59
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• 2002

Delamination means that cracking occurs on the interface layer between composite laminates. In this paper, to predict the delamination growth in composite laminates subjected to low-velocity impact, the unit load method was introduced, and an eighteen-node 3-D finite element analysis, based on assumed strain mixed formulation, was conducted. Strain energy release rate, necessary to determine the delamination growth, was calculated by using the virtual crack closure technique. The unit load method saves the computation time more than the re-meshing method. The virtual crack closure technique enables the strain energy release rate to be easily calculated, because information of the singular stress field near the crack tip is not required. Hence, the delamination growth in composite laminates that are subjected to low-velocity impact can be efficiently predicted using the above-mentioned methods.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2003.10a
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• pp.225-230
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• 2003

Domestic small and medium ship companies have lack of leisure boat technologies and especially they have a problem about its low performance because of the overweight of boat hull. So it is necessary to have alternative manufacturing process to improve the mechanical properties of composite material. In this study, a vacuum curing system was developed as an alternative manufacturing process and then changed the fiber volume fractions of GFRP laminates. The properties of GFRP laminates such as void contents, Young's modulus and fracture toughness were determined for various fiber volume fractions.

• Proceedings of the KSME Conference
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• 2001.11a
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• pp.228-233
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• 2001

It is well known that composite laminates are easily damaged by low velocity impact. The damage of composite laminates subjected to impact loading are occurred matrix cracking, delamination, and fiber breakage. The damage of matrix cracking and delamination are reduced suddenly the compressive strength after impact. This study is to evaluate impact characteristics and the relationship between impact force and inside damage of composite laminates by low velocity impact loading. UT C-scan is used to determine impact damage areas by impact loading.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.2
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• pp.354-362
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• 1995

The finite element modeling is used to study the buckling and postbuckling behavior of composite laminates with an embedded delamination. Degenerated shell element and rigid beam element are utilized for the finite element modeling. In the nonlinear finite element formulation, the updated Lagrangian description method based on the second Piola-Kirchhoff stress tensor and the Green strain tensor is used. The buckling and postbuckling behavior of composite laminates with a delamination are investigated for various delamination sizes, stacking sequences, and boundary conditions. It is shown that the buckling load and postbuckling behavior of composite laminates depend on the buckling model which is determined by the delamination size, stacking sequence and boundary condition. Also, results show that introduction of couplings can reduce greatly the buckling load.

• Advanced Composite Materials
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• v.16 no.4
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• pp.349-360
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• 2007

Recently, natural fiber reinforced composite is attracting attention and considered as an environmentally friendly material. Usually cellulosic fibers are used to reinforce the composites, but some protein fibers such as silk and wool serve the same purpose. In this paper, we proposed a method of producing artistic composite from artistic fabric by using silk fiber reinforced biodegradable plastic, which is designated as 'silk composite', for reinforcement. In order to expand applications of the silk composite, we performed the compression molding of decorative laminates with woody material, which was selected as a core material, and examined the properties of molded decorative laminates with various content of the silk composite. Since plywood and medium-density fiberboard (MDF) are widely used for decorative laminates, we selected them as core materials. As a result, flexible decorative laminates with high flexural strength were obtained by compounding the silk composite with wood materials.