• Title/Summary/Keyword: 섬유 개수

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Flexural Strengthening Effects of RC Beam Reinforced with Pre-stressing Plate (긴장을 가한 보강 플레이트로 보강된 RC 보의 휨보강 효과)

  • Ha, Sang-Su
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.23 no.1
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    • pp.171-178
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    • 2019
  • Fiber-reinforced polymer (FRP) composites have proved to be reliable as strengthening materials. Most of existing studies used single types of FRP composites. Therefore, in this experimental study, carbon FRP sheet, aramid FRP sheet, and hybrid FRP plate including glass fibers were fabricated, and the effect of pre-stressed FRP composites on flexural strengthening of reinforced concrete (RC) beams was investigated. In total, eight RC beam specimens were fabricated, including one control beam (specimen N) without FRP composites and seven FRP-strengthened beams. The main parameters were type of FRP composite, the number of anchors used for pre-stressing, and thickness of FRP plates. As a result, the beam strengthened with pre-stressed FRP plate showed superior performance to the non-strengthened one in terms of initial strength, strength and stiffness at yielding, and ultimate strength. As the number of anchors and thickness of FRP plate (i.e., amount of FRP plates) increased, the strengthening effect increased as well. When hybrid FRP plates were pre-stressed, the strengthening effect was higher in comparison with pre-stressed single type FRP plate.

A study on Phantom image of Mammography in some area (일부지역 유방촬영술의 팬톰영상에 관한 연구)

  • Kang, Se-Sik
    • Journal of radiological science and technology
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    • v.28 no.4
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    • pp.301-306
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    • 2005
  • Purpose : The goal of this study was to survey the quality control of mammographic phantom images in some area. Methods : Between May and June, 2005, I have got a total of 47 mammographic phantom images collected from 49 hospitals and were analized about phantom score of fibrous, speck, tumor with enlargement scope. By critic level of experimental mammographic phantom case images, classified through the pass case that fibrous score 4, speck score 3, tumor score 3 over. Result : It passed 33case (70.3%), failed 14 case (29.7%) about 47 case. Passing case images showed tube voltage $23{\sim}30\;kVp$, tube current $20{\sim}60\;mAs$, photographic density $0.48{\sim}1.77$ Conclusion : It passed case about 70.3% of mammographic phantom image in some area. Optimum range of tube voltage, tube current, photographic density have to use to get fine quality of mammographic images.

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Analysis of RTM Process to Manufacture Composite Bogie Frame Considering Fiber Orientation (섬유방향성을 고려한 복합소재 대차 프레임의 RTM 성형 특성 해석)

  • Kim, Moo Sun;Kim, Jung-Seok;Kim, Seung Mo
    • Journal of the Korean Society for Railway
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    • v.18 no.4
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    • pp.301-308
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    • 2015
  • To reduce the weight of a railroad vehicle, a bogie frame skin is considered for manufacture using an RTM process and composite material. Compared to other processes, RTM has merits in that it demands only simple manufacturing facilities and can produce a large and complex structure in a short cycle time. On the other hand, it is important to determine the proper number and locations of gates and vents to prevent void formation inside a structure. In this study, we numerically predicted the flow pattern in a bogie frame skin during the RTM process by distinguishing the permeability of a fiber mat as isotropic or anisotropic. Using the results, we analyzed the RTM process conditions of the bogie frame to predict skin void formation, mold filling time, and optimum location of vents depending on the permeability conditions.

Static Performance Test for New Wave Dissipating Block Reinforced with FRP (FRP로 보강된 신형 소파블록의 정적 성능 실험)

  • Paik, In-Yeol;Oh, Young-Min
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.23 no.4
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    • pp.285-291
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    • 2011
  • In this study the mechanical performance of the new wave dissipating block is evaluated through experiment and numerical analysis. Also, by selecting adequate reinforcement, the improvement of the structural performance is examined. The reinforcement is designed by predicting the amount of tensile force and the location where the tensile stress develops in the new wave dissipating block through numerical analysis. The new wave dissipating block is reinforced with the ordinary steel bars and the fiber reinforced plastic(FRP) bars which have advantages in ocean environment in terms of corrosion and fatigue. The test result shows that the fracture resistance of the un-reinforced concrete block is 350 kN which is about 6.2 times that of the weight of the block. All the test blocks which are reinforced by either steel of FRP bars show strength capacity of over 900 kN which is the maximum load of the test equipment. Although the single reinforcement with larger-diameter bars has advantage in terms of construction convenience, it is recommended to use multiple number of smaller-diameter bars in order to reduce the crack width.

Image-Based Computational Modeling of Porous Matrix Composites and Calculation of Poroelastic Coefficients (다공성 기지를 갖는 복합재의 이미지 기반 전산 모형화 및 기공 탄성 계수 산출)

  • Kim, Sung Jun;Shin, Eui Sup
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.38 no.5
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    • pp.527-534
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    • 2014
  • Poroelastic analyses of fiber-reinforced composites were performed using image-based computational models. The section image of a porous matrix was analyzed in order to investigate the porosity, number of pores, and distribution of pores. The resolution, location, and size of the section image were considered to quantify the effective elastic modulus, poroelastic parameter, and strain energy density using the image-based computational models. The poroelastic parameter was calculated from the effective elastic modulus and pore pressure-induced strain. In addition, the results of the poroelastic analyses were verified through representative volume elements by simplifying various pore configurations and arrangements.

Long-term Behavior of Deck-plate Concrete Slab Reinforced with Steel Fiber (강섬유 보강 데크플레이트 콘크리트 슬래브의 장기 거동)

  • Hong, Geon-Ho;Hwang, Seung-Koo
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.21 no.4
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    • pp.30-38
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    • 2017
  • Recently, research on the development of a composite slab system for shorting the construction period by simplifying the process by omitting the form work and the reinforcement placing is underway. The purpose of this study is to evaluate the long-term behavior of a simplified slab system that replaces the form work and tensile reinforcement using structural deck-plate and replaces the temperature reinforcement using steel fiber reinforced concrete. In the conventional composite deck-plate slab method, w.w.f is generally used for crack control by drying shrinkage. But previous research results by various researchers were pointed out it is not effective to control the shrinkage and temperature cracking. In this study, the long-term cracking and structural behavior of steel fiber reinforced deck plate slab specimen with two continuous spans constructed under typical load conditions were evaluated. Experimental results showed that the number and width of long-term cracks decreased remarkably in the simplified slab specimen, and the deflection was also decreased compared with conventional RC slab specimen. However, in the continuous end of the slab where the negative moment is applied, it is analyzed that reinforced details are necessary to control the crack width in the service load and to recover deflection at load removal.

Design of Composite Laminates Using Enumeration Method (나열법을 이용한 복합재 적층판 설계)

  • Joung, Chanwoo;Bae, Il-Joon;Park, Young-Bin
    • Composites Research
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    • v.33 no.5
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    • pp.288-295
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    • 2020
  • Fiber-reinforced composite laminates have high specific stiffness and strength and are expected to be useful for weight reduction in weight-sensitive industries, such as automotive and aerospace. However, designing composite laminates is often dependent on designer's experience and intuition because of difficulties in determining the number of plies and stacking sequence, which tends to lead to over-design. In this study, optimal design of composite laminates was performed to minimize weight, while withstanding the given load. Based on the enumeration method, all combinations of stacking sequence satisfying the design guideline for composite laminates were considered. Composite laminates were discretized into panels. Optimal number of plies and stacking sequence for each panel were determined considering local load on each panel and contiguity across adjacent panels. Failure index from Tsai-Wu criteria was optimized for strength and buckling analysis was performed for compressive load. Stacking angles of 0, ±45 and 90° were used.

Study on the Marine Debris on the Seabed in Chinhae Bay, Korea (진해만의 바다밑 쓰레기에 대한 조사연구)

  • Koo Bon-Sam;Kang Hun;Hur Sung-Hoi
    • Journal of the Korean Society for Marine Environment & Energy
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    • v.3 no.4
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    • pp.91-98
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    • 2000
  • The present study is the first attempt involving quantification of the different types of debris found on the seabed of Chinhae Bay in the South Sea of Korea. Eleven cruises were undertaken to collect marine debris samples by bottom trawling from February in 1998 to January in 1999. The tows were conducted over a period of 60-90 min, and eight types of debris were counted: plastic, fishing gear, metallic objects, wood, rubber or leather, glass, textile and the others. Results are obtained based on the number and weight of the objects classified as per eight categories and station for a trawling period. The results of this study are that the number and weight of debris found per unit of swept area (1 hectare) were surveyed as 27.8(1,612 in total) and 3,130 g(193,820 g in total), and plastic and fishing gear have the most composition of marine debris by number, on the other hand, metallic objects and fishing gear have the most composition of marine debris by weight.

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Experiment on Flexural Analysis of RC Beams Strengthened with Composite Material Panel (복합재료 패널로 보강된 철근 콘크리트 보의 휨 실험)

  • Kim, Jin-Man;Jung, Mi-Roo;Lee, Jae-Hong;Yoon, Kwang-Sup
    • Journal of Korean Association for Spatial Structures
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    • v.10 no.2
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    • pp.117-126
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    • 2010
  • Experiment on flexural analysis of RC beams strengthened with composite material panel is presented. Recently, the strengthening of reinforced concrete structures using advanced fiber reinforced plastic (FRP) composites, and in particular the behavior of FRP-reinforced concrete structure is topic that has become very popular because of good corrosion resistance and easy for site handling due to their light weight. In this study, an efficient computational analysis using ABAQUS to predict the ultimate moment capacity of reinforced concrete beams strengthened with FRP is presented. Test parameters in this study are the shape of fiber arrangement (LT, DB, DBT) and the number of carbon fiber sheets (2ply, 3ply). When comparing with results of the analytical model, results of the experiments show similar values. Furthermore, reinforced concrete beam with FRP obtains improved effects for ultimate strength.

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A numerical study on the safety of tunnel face using face bolting method (페이스 볼트 공법을 이용한 터널 막장 안정성에 관한 수치해석적 연구)

  • Ra, Jee-Hyun;Yoon, Ji-Sun
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.9 no.1
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    • pp.83-89
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    • 2007
  • As tunnel excavation generats stress release, a stability security of tunnel face is mainly important in case of tunnel excavation in the weak grounds. Using the steel bar or glass fiber pipe which had regular hardness, a face bolt method to reinforce previously is applied to an excavation object tunnel face aspect among measures methods regarding this. Therefore, used $FLAC^{3D}$ Ver. 2.1 on 5 Case of 0.5D (2EA), 1.0D, 1.5D, 2.0D with the length and 6 Case of 0, 20, 40, 60, 80, 100EA with the number of the bolt that a face bolt method was installed at these papers in the necessary weak grounds in order to review applicability of the tunnel face reinforcement method that used these face bolts, and executed three dimension continuous analysis.

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