• Title/Summary/Keyword: 강화재

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Analysis of Thermal Conductivities of Carbon/Phenolic and Silica/Phenolic Ablative Composites by Laser Pulse Method (레이저 섬광법을 이용한 Carbon/Phenolic 및 Silica/Phenolic 내열복합재료의 열전도도 분석)

  • Kim, H.Y.;Kim, P.W.;Hong, S.H.;Kim, Y.C.;Yeh, B.H.;Jung, B
    • Composites Research
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    • v.12 no.3
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    • pp.75-83
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    • 1999
  • The thermal properties of carbon/phenolic and silica/phenolic ablative composites were investigated by measuring the heat capacity, thermal diffusivity and thermal conductivity. The heat capacities of carbon/ phenolic and silica/phenolic composites were calculated from differential scanning calorimeter curve. The thermal diffusivities of carbon/phenolic and silica/phenolic composites were measured by the laser flash method with varying laminated direction, i.e., with laminar direction and across laminar direction. The thermal diffusivities decreased with increasing temperature. The thermal conductivities of carbon/phenolic and silica/phenolic composites were calculated using the heat capacity, density and thermal diffusivity. The thermal conductivities increased with increasing temperature. The thermal conductivity of with laminar direction is two times higher than that of across-laminar direction in carbon/phenolic composite due to the directionality of thermal conductivity of carbon fiber. The thermal conductivities of two dimensional fiber reinforced composites were analyzed using the conductivities of constituents and volume fraction of each constituent. The thermal conductivities of carbon fiber and silica fiber were calculated from thermal conductivities of carbon/phenolic and silica/phenolic composites. The thermal conductivities of carbon/phenolic and silica/phenolic composites at RT were predicted from thermal conductivities of fiber and resin with varying the volume fraction of fiber.

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Experimental Study on the Strengthening Method of RC Beam Using Ceramic Metal (세라믹메탈재를 적용한 RC보의 보강공법에 관한 실험적 연구)

  • Shim, Nak-Hoon;Park, Young-Suk
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.8 no.4
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    • pp.115-122
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    • 2004
  • The objective of the present study is to understand the strengthening effects of reinforced concrete beam applied the reinforced plates, expended metal and carbon fiber grid with the ceramic metal. In the present study, the bending tests are performed to understand the increasing effects of stiffness and ductility for the strengthening RC beam. Also, the important purpose of the structural tests is to understand the adhesion performance of the ceramic metal. It is expected the present experimental observations as a valuable source in suggestion improved the strengthening method more than this method by analysis of the failure mode for the specimens.

Redesigning Archival Appraisal Policies for Improving Accountability of Public Bodies (공공기관의 책임성 강화를 위한 기록평가제도의 재설계)

  • Seol, Moon-won
    • The Korean Journal of Archival Studies
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    • no.55
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    • pp.5-38
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    • 2018
  • Trust in government agencies is closely related to accountability. The key strategy to increase public accountability is to document the processes and outcomes of their key tasks and policies adequately. The purpose of this study is to suggest a redesign of the records appraisal policy to enhance the accountability of government agencies. Applying the newly introduced concept of appraisal in ISO 15489-1: 2016, the relationship between accountability and appraisal is articulated and the problems of records appraisal systems in terms of accountability are analyzed. Based on this analysis, it suggests the principles for reforming the appraisal policies well as the redesign of the current disposition authorities as a key tool for appraisal, and the introduction of records disposal freeze system.

Comparison of Machining Defects by Cutting Condition in Hybird FRP Drilling (유리탄소섬유 하이브리드 복합재의 절삭 조건에 따른 가공 결함 비교)

  • Baek, Jong-Hyun;Kim, Su-Jin
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.21 no.9
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    • pp.12-20
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    • 2022
  • Delamination and burr defects are important problems in drilling fiber reinforced plastics. A method for measuring FRP drilling defects has been studied. Delamination and burr factors were defined as the relative length or area. Using these factors, the effects of tool shape and drilling conditions on delamination and burr were studied. In this study, the defects that occur when drilling a glass-carbon fiber hybrid composite were compared in terms of three factors. In the glass-carbon fiber hybrid composite, the effects of the feed rate and tool point angle on the delamination and burr factors were similar to those in previous studies. The diameter of the tool did not affect the defect factor. A circular burr was generated in a drill tool with a point angle of 184°, and a relatively small deburring factor was observed compared with a tool with a point angle of 140°.

An Experimental Study on the Strength of Two Serial Bolt-Fastened Composite Joints under Elevated Temperature and Humid Condition (고온다습 조건($82.2^{\circ}C$)에서 2열 볼트 체결 복합재 조인트의 강도에 관한 실험적 연구)

  • Kim, Hyo-Jin
    • Composites Research
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    • v.22 no.5
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    • pp.30-36
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    • 2009
  • The failure strengths and modes in carbon fiber reinforced polymeric composites, with two serial bolt-fastened composite joints, were investigated to evaluate the typical joint configurations of composite components. The parametric studies were performed experimentally at room temperature dry and elevated temperature wet, $82.2^{\circ}C$ on several different laminate configurations. Based on the experimental data presented, two basic load-displacements curves are observed. Each failure mode has the characteristic curve. It is showed that the bearing failure mode occurs in elevated temperature wet condition. It is analysed that the strength of bearing failure mode is not highly depending on the effective modulus of specimen. The failure strength at elevated temperature wet is decreased by the cause of interfacial deterioration between fiber and matrix with moisture absorption.

Management of complicated crown fracture by tooth fragment reattachment with fiber post: a case report (섬유 강화형 포스트를 이용한 치관 파절된 치아의 재부착: 증례보고)

  • Kim, Yu-Ri;Jung, Kyoung-Hwa;Son, Sung-Ae;Park, Jeong-Kil
    • Journal of Dental Rehabilitation and Applied Science
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    • v.37 no.4
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    • pp.251-258
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    • 2021
  • Dental trauma is very common in children and relatively young people, with the line of treatment depending on the time elapsed, age of the child, and tooth maturity. If the fractured segment is available and there is close approximation of the segment to the remaining tooth, reattachment of the fractured segment is a feasible option. This treatment offers several advantages, including the reestablishment of function, aesthetics, shape, shine and surface texture, in addition to the original contour and alignment of the teeth. The following cases present two different complex crown fracture cases that were treated using tooth fragment reattachment with fiber-reinforced composite post.

Effect of Cold Temperature Dry and Elevated Temperature Wet on Mechanical Properties of CFRP Composites (냉각($-55^{\circ}C$) 및 고온다습 조건($82.2^{\circ}C$)이 탄소섬유강화 복합재의 기계적 특성에 미치는 영향 연구)

  • Kim, Hyo-Jin;Lee, Sih-Joong;Han, Sang-Ho;Kim, Sang-Kuk;Park, Seong-Jun
    • Composites Research
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    • v.22 no.3
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    • pp.60-65
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    • 2009
  • The mechanical behavior of carbon fiber reinforced polymeric (CFRP) composites was investigated. Both strength and modulus were measured at room temperature dry, cold temperature dry, $-55^{\circ}C$, and elevated temperature wet, $82.2^{\circ}C$ on seven different laminate configurations consisting of $[0_6]_T$, $[90_{12}]_T$, $[0_{16}]_T$ and $[90_{16}]_T$ unidirectional laminates, $[{\pm}45]_{5S}$ angle-ply laminate, $[0/90_{12}/0]_T$ cross-ply laminate, a 36-ply laminate $[0/45/-45/45/-45/0]_{3S}$. Based on the experimental data presented, it is shown that the strength at cold temperature dry, $-55^{\circ}C$ is increased with the brittleness of fiber or matrix. Moreover, it is shown that both shear strength and modulus at elevated temperature wet, $82.2^{\circ}C$ are decreased by the cause of interfacial deterioration between fiber and matrix with moisture absorption.