• Title/Summary/Keyword: Apparent stiffness

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Material property optimization of Pultruded FRP bridge deck section (인발성형 FRP 바닥판의 물성 최적화)

  • 최영민;조효남;이종순;김희성
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 2004.04a
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    • pp.135-142
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    • 2004
  • The apparent advantages of FRP (fiber reinforced plastics) composites over the conventional structural materials may be attributed to their high specific strength and stiffness. Other affordable properties of FRPs including an excellent durability make them particularly attractive for the structures in severe service conditions. Therefore, the material and sectional properties of a FRP structural component should be designed to meet its specific requirements and service conditions. This paper is performed the material property optimization under optimum design of pultruded FRP bridge deck section. In the problem formulation, an objective function is selected to minimize the maximum R(strength ratio). The thickness of layers, volumes of fibers and matrix fiber orientation, and stacking sequence of FRPs are used as the design variables. Strength ratio in the design code, material failure criteria and pultruded manufacture thickness are selected as the design constraints to enhance the material performance of FRP decks. From the results of the numerical investigation, we obtained the optimum deck section profile for conventional using object.

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Effect of HwBKP and HwBCTMP on the Characteristics of Printing Paper (HwBKP 및 HwBCTMP가 인쇄용지(印刷用紙)의 특성에 미치는 영향)

  • Won, Jong Myoung;Nam, Ki Young
    • Journal of Forest and Environmental Science
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    • v.8 no.1
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    • pp.67-76
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    • 1992
  • The effects of HwBCTMP on the characteristics of paper were compared with those of HwBKP. The fiber fraction below 0.1 mm of HwBCTMP was higher than those of HwBKP. HwBCTMP was superior to the HwBKP in the improvement of opacity, apparent density and smoothness, and in the decrease of air permeability. The strength properties and stiffness obtained with the addition of HwBCTMP were better than those of HwBKP. Therefore, HwBCTMP might not only be well substituted for HwBKP but also decrease production cost and improve paper properties.

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Clinical Characteristics of Trauma-Related Chronic Osteomyelitis in 3 Wild Raccoon Dogs (Nyctereutes procyonoides)

  • Ha, Minjong;Ahmed, Sohail;Lee, Do Na;Han, Janghee;Yoon, Junghee;Yeon, Seong-Chan
    • Journal of Veterinary Clinics
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    • v.39 no.3
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    • pp.131-137
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    • 2022
  • Osteomyelitis typically occurs because of the direct inoculation of bacteria or fungi after penetrating trauma or surgical contamination or, by extension, from soft tissue infection. Osteomyelitis is rarely reported in wildlife animals, though severe chronic osteomyelitis cases do exist in wildlife owing to the scarcity of medical support in the wild environment. This report describes three cases of chronic osteomyelitis in wild raccoon dogs related to trauma. The typical symptoms of three reported cases were ataxia, stiffness, muscle atrophy, and lethargy. All three cases were relevant to traumatic or severe external injury, and skin infestation caused by ectoparasites was apparent on an ocular inspection. In the radiographic examination, diffuse sites of osteolytic lesions and remarkable periosteal responses were demonstrated around the injured limb in all three cases. Apparent neutrophilia with a left shift, lymphocytosis, and monocytosis in hematological examinations generally indicated chronic infection as shown in case 1 and 3. Treatment was attempted with broad-spectrum antibiotics and non-steroidal anti-inflammatory drugs, such as amoxicillin/clavulanic acid, enrofloxacin, clindamycin, and meloxicam. These treatment options helped improve the overall prognosis of chronic osteomyelitis, but the outcomes did not meet the treatment goal entirely. Osteomyelitis can be extremely challenging to treat, particularly in wild animals, because of their distinctive traits, such as masking phenomenon and uncontrolled exposure to ectoparasites. Earlier diagnosis with a radiographic examination, hematological examinations, and careful patient monitoring, followed by prolonged antibiotic therapy and restricted exercise, are the key factors leading to a better prognosis.

Investigation of microstructure and surface effects on vibrational characteristics of nanobeams based on nonlocal couple stress theory

  • Shariati, Ali;Barati, Mohammad Reza;Ebrahimi, Farzad;Toghroli, Ali
    • Advances in nano research
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    • v.8 no.3
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    • pp.191-202
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    • 2020
  • The article brings the study of nonlocal, surface and the couple stress together to apparent the frequency retaliation of FG nanobeams (Functionally graded). For the examination of frequency retaliation, the article considers the accurate spot of neutral axis. This article aims to enhance the coherence of proposed model to accurately encapsulate the significant effects of the nonlocal stress field, size effects together with material length scale parameters. These considered parameters are assimilated through what are referred to as modified couple stress as well as nonlocal elasticity theories, which encompasses the stiffness-hardening and softening influence on the nanobeams frequency characteristics. Power-law distribution is followed by the functional gradation of the material across the beam width in the considered structure of the article. Following the well-known Hamilton's principle, fundamental basic equations alongside their correlated boundary conditions are solved analytically. Validation of the study is also done with published result. Distinct parameters (such as surface energy, slenderness ratio, as nonlocal material length scale and power-law exponent) influence is depicted graphically following the boundary conditions on non-dimensional FG nanobeams frequency.

Emulsion Graft Copolymerization of Methyl Methacrylate onto Cotton Fiber (면섬유에 대한 Methyl Methacrylate의 유화 그라프트 중합)

  • Bae Hyun-Sook;Ryu Hyo-Seon;Kim Sung-Reon
    • Journal of the Korean Society of Clothing and Textiles
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    • v.15 no.3 s.39
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    • pp.271-280
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    • 1991
  • Emulsion graft copolymerization of MMA onto cotton fiber using Ce(IV) salt as an initiator was carried out. Graft yield and graft efficiency were observed according to the kinds and concentrations of emulsifier and polymerization conditions. The physical properties of MMA grafted cotton fabric were investigated. The results of this study were as follows: 1. The heighest graft yield of emulsion graft polymerization occurred at the concentration below cmc of emulsifier, which was different from emulsion polymerization. Nonionic sur- factant as an emulsifier was more effective than anionic one. 2. The highest graft yield was obtained at the initiator concentration $1{\times}10^{-2}mol/l$. The viscometric molecular weight of PMMA was in the order of 106. 3. As reaction time increased, the graft yield increased but the graft efficiency decreased. 4. Elevation of reaction temperature resulted in increase of graft yield. The apparent activation energy of MMA graft polymerization was 4.72 Kcal/mol. 5. Physical properties of MMA grafted cotton fabric varied with increase of grafting. Thickness and stiffness showed a noticeable increase, whereas tensile strength and elongation was slightly increased. Crease recovery increased as the graft yield increase up to $50\%$ and decreased thereafter.

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Modification of KOCC with Ultrasonic Wave Treatment (초음파처리에 의한 KOCC의 개질)

  • Ming, He;Lee, Yong-Kyu;Won, Jong Myoung
    • Journal of Korea Technical Association of The Pulp and Paper Industry
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    • v.45 no.5
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    • pp.44-48
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    • 2013
  • Ultrasonic treatment of KOCC was tried to explore the possibility for improvement of KOCC quality as a raw material for making industrial packaging paper and paperboard. The effect of pH, stock consistencies and treatment times on the ultrasonic response of KOCC were investigated. WRV, apparent density, tensile index and burst index were improved as pH of KOCC slurry is increased. However highest tear index and stiffness were obtained at pH 8. It was also found that the highest WRV and strength properties could be obtained at 0.5% of KOCC consistency during ultrasonic treatment. WRV and most strength properties were improved with ultrasonic treatment time. It was found that ultrasonic treatment can be used as a useful mean for KOCC modificaton.

The Variation of Mechanical Properties with Directions of PET High Stretch Fabrics (PET 고신축사 직물의 방향에 따른 역학적 특성의 변화)

  • 김영민;박종범;김주애;조현혹
    • Journal of the Korean Society of Clothing and Textiles
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    • v.26 no.1
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    • pp.160-167
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    • 2002
  • Stretch fabrics are wide-spread for high performance clothing use with requirements of fitness and adaptability to human's movement. A newly developed 100% PET high stretch fabric has excellent properties with respect to stretch, softness, bulkiness, and apparent volume compared to PET filament fabrics. The 100% PET high stretch fabric shows advantages of a dimensional stability, dye and agent adaptability in dying and finishing process, a property of stretch recovery after washing and lower production cost than that of spandex fabric. KES-FB was used to measure mechanical properties to various directions of the fabric. This study centered on whether the 100% PET high stretch fabric is suitable to quality and shape retention of fabric by testing several properties including tensile, compression, shear, bending and surface characteristic to various measuring directions. Tensile linearity showed maximum value at $0^{\circ}$ in plain and $90^{\circ}$ in twill. Shear Stiffness of plain and twill showed maximum value equally at $45^{\circ}\;and\;135^{\circ}$. Bending rigidity showed maximum value at $0^{\circ}$ in plain and $45^{\circ}$ twill. Mean deviation of MIU showed maximum value at $0^{\circ}\;and\;90^{\circ}$ in plain and $135^{\circ}$ in twill.

Bacterial Pattern Formation in Response to the Stiffness of Substrates (접촉 표면의 강성 변화에 따른 박테리아의 군집 패턴)

  • Kim, J.K.;Park, E.J.;Kim, S.R.;Cho, M.Y.;Han, H.
    • 한국가시화정보학회:학술대회논문집
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    • 2007.11a
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    • pp.88-91
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    • 2007
  • Animal cells show different behaviors in response to the mechanical properties of the substrates. We hypothesize that the rigidity of the substrates also affects the bacterial motility and controls the colony dynamics. It is found that the colony size of Escherichia colis and Bacillus subtilis grown on the agar plates is correlated with agarose gel concentrations and thus with the substrate rigidity. High- resolution microscopic imaging reveals that bacteria in single colonies form different aggregation patterns on the agar plates with varying gel concentration. We measured the apparent diffusion coefficients in the agarose gel plates made with different gel concentrations. Mathematical modeling and quantitative imaging of dye dispersion in the agar plates suggest that there is a close connection between the diffusion rate and the colony size. Nanoscale pore structures and kinetic constraints in the porous media may have an effect on bacterial colony dynamics.

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A Study on Mechanical Characteristics of Interface of Ceramic/Metal Composites (세라믹/금속 이종재료 계면의 기계적 특성에 관한 연구)

  • Seo, Do-Won;Kim, Hak-Kun;Song, Jun-Hee;Lim, Jae-Kyoo;Park, Chan-Gyung
    • Proceedings of the KSME Conference
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    • 2000.04a
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    • pp.121-126
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    • 2000
  • Metal/Ceramic structures have many attractive properties, with great potential for applications that demand high stiffness, as well as chemical and biological stability, thermal and electrical insulation. They are currently in use for mechanical and thermal protection in cutting tool and engine parts. With all their great advantage, ceramics suffer from one major problem they are brittle, and are especially susceptible to cracking from surface contacts. Delamination at the interfaces with adjacent layers is a particularly disturbing problem, and can cause premature failure of a composite system. so determination of adhesive properties of coating is one of the most important problems for the extension of the use of coated materials. In this work, mechanical characteristics of Interface of ceramic/Metal composites are evaluated by means of hardness test, indentation test apparent interfacial toughness and bonding strength test. The interface indentation test provides a relation between the applied load(P) and the length of the crack(a) created at the interface between the coating and the substrate.

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Development of Resistivity Seismic Flat Dilatometer Testing System for Characterizing Soft Soil Site (연약지반조사를 위한 전기비저항 탄성파 Flat DMT 장비의 개발 및 적용)

  • Bang, Eun-Seok;Sung, Nak-Hoon;Kim, Yeong-Sang;Park, Sam-Kyu;Kim, Jung-Ho;Kim, Dong-Soo
    • 한국지구물리탐사학회:학술대회논문집
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    • 2007.06a
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    • pp.251-256
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    • 2007
  • The aim of this paper is development of resistivity seismic dilatometer (RSDMT) system. The resistivity module for obtaining apparent resistivity depth plot and seismic module for obtaining shear wave velocity (Vs) depth plot are attached to the conventional flat dilatometer testing equipment. From shear wave velocity profile, the stiffness at low strains of a site can be evaluated in undisturbed condition. And the resistivity value contains some information about water content and mineral characteristics of clayey soil. Specially manufactured resistivity and seismic modules were connected between commercialized DMT blade and drilling rod. To enhance reliability and repeatability of RSDMT test, automatic testing system including notebook based data acquisition system and automatic surface source system were developed. RSDMT system can be performed rapidly and can obtaine more reliable data at the same point compared with the separated testing system. The verification studies for the developed RSDMT system are going to be performed. From these studies, the effectiveness of integrated hybrid testing system will be checked in light of proper evaluation of geotechnical design parameters of clayey soils.

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