• Title/Summary/Keyword: tensile breaking

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Finite Element Analysis for Breaking of Glass Using Laser (레이저를 이용한 유리절단의 유한요소해석)

  • Cho, Hae-Yong;Kim, Kwan-Woo;Nam, Gi-Jeong;Lee, Jae-Hoon;Suh, Jeong
    • Laser Solutions
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    • v.9 no.1
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    • pp.9-16
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    • 2006
  • Glass is one of brittle materials. Generally, brittle material is weak for tensile stress but strong for compression stress. Laser breaking of glass used this brittle characteristics. Laser breaking of glass was simulated to optimize breaking condition by using commercial FEM code MARC which is applicable to thermo-mechanical coupling analysis. Various shapes of heat sources were applied to the analysis and the distance between heating and cooling source were varied for each simulation. The shapes of heat sources were circle, single and double ellipse and the distance was varied from 0mm to 30mm. Moving heat sources were designed on the basis of experimental condition. As a result, double elliptic shape of heat source was the most suitable among them in laser breaking of glass. And it should be useful to determine optimal condition of laser breaking for glass.

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Study on the Novel Materials Containing Nanoparticles and Isocyanate Group for Strength Improvement of Hydrogel Ophthalmic Lens

  • Lee, Min-Jae;Sung, A-Young
    • Journal of Integrative Natural Science
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    • v.11 no.2
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    • pp.113-120
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    • 2018
  • This study was planned to prepare the high strength hydrogel ophthalmic lens containing isocyanate group and nanoparticles. HDI with carbon nanoparticles were used as additives for the basic combination of HEMA, MA and MMA, and the materials were copolymerized with EGDMA as the cross-linking agent and AIBN as the initiator. The mixture was heated at $100^{\circ}C$ for an hour to produce the high performance hydrogel ophthalmic lens by cast mold method. Measurement of the physical characteristics of the produced material showed that the refractive index was in the range of 1.4027~1.4600, water content 25.21~44.01%, contact angle $54.18{\sim}72.94^{\circ}$, visible light transmittance 53.03~92.09%, and tensile strength 0.1024~0.2359 kgf and breaking strength was 0.0872~0.2825 kgf. The results showed an increase of refractive index while the decrease in water content. And also, the breaking strength was highest when the addition ratio of HDI was 5%(wt). As a result of the absorbance measurement, no significant difference was observed in all the samples, so it can be judged that the stabilization of nanoparticles in the polymer was maintained.

Properties of WPC Prepared with Various Size and Amount of Wood Particle (목편의 크기와 함량이 복합재료의 물성에 미치는 영향)

  • Kim, Chul-Hyun;Kim, Kang-Jae;Eom, Tae-Jin
    • Journal of Korea Technical Association of The Pulp and Paper Industry
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    • v.40 no.3
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    • pp.59-64
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    • 2008
  • The mechanical properties of WPC(wood plastic composite) should effected with the size of wood particle size and also characteristics of wood particles. In this paper, WPC were prepared with various size of wood particles and coupling agent and the mechanical properties were evaluated. The smaller size of wood particle were used for WPC, the higher properties of WPC in tensile strength and breaking elongation were obtained. The smaller amount of wood particle were used for WPC, the higher properties of WPC in tensile strength and breaking elongation were obtained.

Seam Strength Depending on the Change of Stitch Density of Fine Cotton Fabrics (세번수 면직물의 땀수 변화에 따른 봉합강도)

  • Uh, Mi-Kyung
    • Journal of the Korea Fashion and Costume Design Association
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    • v.15 no.2
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    • pp.57-64
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    • 2013
  • As the clothing materials have been more functional and advanced, the cotton fabrics for dress shirts or blouses have been more qualified and the sewability for high degree of completion has been required. This study aims to identify the seam strength depending on the change of stitch density of fine cotton fabrics by fabric and thread and so the general seam performance of fine cotton fabrics by analyzing the seam efficiency and breaking mode of seams. For an experiment, 3 kinds of fine cotton fabrics and 2 kinds of threads were selected and the sample was made by changing the stitch density by four steps. Then, the seam strength was measured. Next, the seam efficiency and breaking mode of seams were analyzed on the basis of the results of seam strength measurement. The results are as follows: All fabrics showed the similar tendency in seam strength. The seam strength is related to the tensile strength and thread strength, it increased only to a certain stitch density. When the stitch density exceeded a certain level, fabrics were destroyed or threads were cut. Then, the seam strength didn't increase. Furthermore, the more the seam strength increased, the more the seam efficiency increased. For increasing the maximum stitch density, it was required to use the fabrics and threads which had similar properties, in other words, the high thread strength for the high tensile strength and the low thread strength for the high tensile strength.

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Orientation properties of Korean traditional paper-Hanji (전통한지의 종이 방향성)

  • Yoon, Seung-Lak;Ra, Jong-Bum
    • Journal of Korea Technical Association of The Pulp and Paper Industry
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    • v.45 no.3
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    • pp.52-58
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    • 2013
  • To evaluate the anisotropic characteristics of Korean traditional paper-Hanji, the physical and mechanical characteristics of hand-made hanji, and machine-made hanji were investigated in this research. The densities of copying paper and newsprint paper appeared to be two times higher than the densities of hand-made hanji using Ssangbal sheet forming and hanji made of paper mulberry fiber. The breaking length, and tear index of both Hanji using Owangbal sheet forming, and hand-made Hanji using Ssangbal sheet forming appeared to be different according to the directions in paper. The breaking lengths of Hanji using Owangbal sheet forming showed little differences according to the directions. Breaking length of Hanji using Ssangbal sheet were slightly higher than those of Hanji using Owangbla sheet forming. The breaking lengths of machine-made hanji, copying paper, and newsprint paper were two to four times higher than those of hand-made Hanji. The breaking length showed higher differences according to the direction than the tear index. The tensile strength according to the directions in paper showed significant differences (${\alpha}$=0.05) in all papers used in this research.

Varietal Differences of Pod Shedding (땅콩 낙협 정도의 품종간차이)

  • 진일두;김규태
    • KOREAN JOURNAL OF CROP SCIENCE
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    • v.36 no.6
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    • pp.532-539
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    • 1991
  • This study was conducted to screen genetic stock for resistant to pod shedding. Materials used were 7 recommended varieties in Korea and 211 introduced varieties containing 94 Virginia type, 99 Spanish type and 18 Valencia type varieties. the days from seeding to first anthesis. number of mature pods per plant. 100 seeds weight and shedded pod ratio per total mature pod at harvesting were investigated. And the breaking tensile strength required to detach a pod from its gynophore was measured at a proper time for harvesting of each variety. In addition. factors related to pod shedding were discussed. The first anthesis of Spanish and Valencia types were earlier than that of Virginia type, but Korean recommended varieties which were recognized as Virginia type had relatively earlier anthesis. The varieties of Spanish type yielded more pods compared with those of Valencia and Virginia types. but Korean recom-mended varieties yielded slightly more pods than the others. Seeds weight of Korean recommended varieties was larger than not merely those of Spanish and Valencia types which were small seeds but also those of Virginia type which were large seeds. The breaking tensile strengths between pod and gynophore were various among the varieties belonging to same type. The strength was relatively strong in the Spanish type, but weak in both Virginia type and Korean recommended varieties. Therefore, pod shedding in the varieties of Spanish type was low and high in Virginia type and Korean recommended varieties. There were positive or negative correlations at the 0.1 % significan level among the days to first anthesis. number of pods per plant. seed weight, breaking tensile strength and shedding ratio. The pod shedding is considered a compound character that is affected by the factors such as breaking tensile strength between pod and gynophore, number of pods per plant and seed size.

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The Effect of Administration of Steroid on the Wound Breaking Tensile Strength in Rats (백서에서 스테로이드 투여가 창상 파열장력에 미치는 영향)

  • Kwon, Nam Ho;Kim, Han Koo;Kim, Woo Seob;Bae, Tae Hui
    • Archives of Plastic Surgery
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    • v.36 no.5
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    • pp.538-542
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    • 2009
  • Purpose: The successful wound healing means the scarless wound with adequate strength. It has been shown in vivo and in vitro that steroid retard the collagen synthesis. We studied the effect of steroid on the wound breaking strength in rats. Methods: 40 Sprague - Dawley rats were evenly assigned to two groups. One group was served as control, the other group was experimental. We made dorsal midline incision and closed the wound. In the experimental group, we medicated methylprednisolone (0.15 mg/g/day) for 1 week. Then, we compared the differences of the breaking strength and microscopic histology between control and experimental group at 2, 4, 6 and 8 week. Results: Up to 4 week, the breaking strength of the experimental group was markedly decreased than that of control group, while at 6 week the strength of experimental group attained to that of control group nearly. In histologic findings, control group demonstrated dense organization of collagen to experimental group at 4th week. Conclusion: In this experiment, steroid significantly inhibited the strength gain in wound at early period of the wound healing process. When using steroid after the surgery or the wound formation, it is desirable to administrate carefully and need thorough wound management to prevent delayed wound healing.

The Estimation of Dynamic/Impact Strength Characteristics of High Tensile Steel by Dynamic Lethargy Coefficient (동적무기력계수에 의한 고장력강의 동적.충격강도 특성 평가)

  • 송준혁;박정민;채희창;강희용;양성모
    • Transactions of the Korean Society of Automotive Engineers
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    • v.10 no.2
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    • pp.96-100
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    • 2002
  • The purpose of this paper is presented a rational method of predicting dynamic/impact tensile strength of high tensile steel materials widely used fur structural material of automobiles. It is known that the ultimate strength is related with the loading speed and the Lethargy Coefficient from the tensile test. The Dynamic Lethargy Coefficient is proportional to the disorientation of the molecular structure and indicates the magnitude of defects resulting from the probability of breaking the bonds responsible for its strength. The coefficient is obtained from the simple tensile test such as failure time and stresses at fracture. These factors not only affect the static strength but also have a great influence on the dynamic/impact characteristics of the joist and the adjacent structures. This strength is used to analyze the failure life prediction of mechanical system by virtue of its material fracture. The impact tensile test is performed to evaluate the life parameters due to loading speed with the proposed method. Also the evaluation of the dynamic/impact effect on the material tensile strength characteristics is compared with the result of Campbell-Cooper equation to verify the proposed method.

Longitudinal Force Analysis of CWR on High Speed Rail Bridges (고속철도 교량상의 장대레일 축력 해석)

  • 이지하;양신추;이종득
    • Proceedings of the KSR Conference
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    • 1998.05a
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    • pp.556-563
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    • 1998
  • Railway bridges have a significant effect on the stress and displacement of continuous welded rail(CWR). Longitudinal compression force at high temperature, combined breaking or acceleration forces can introduce track buckling. On the other hand, longitudinal tensile forces, associated with low temperatures, in combination with breaking forces may break rail. Therefore, it is very important to work out thorough counter measures for those problems, specially in high speed rail which high safety is required. The exact evaluation of longitudinal force of rail has the key to the solution. The main aim of the present paper is to examine whether the longitudinal force of CWR's on Kyung-Bu-HSR satisfy the criteria to be fulfilled in the design of railway bridge. The analyses are carried out by using "CWRAP" program which was developed by our research group. The ballast resistance and breaking force effects on the longitudinal force of CWR are investigated.

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Analysis for Stress According to Pin Type of High Voltage Suspension Type Insulator (초고압 현수애자의 Pin 형상에 따른 응력해석)

  • Cho, H.G.;Park, K.H.
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2001.05c
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    • pp.140-142
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    • 2001
  • In this study mechanical for stress according to Pin type of high voltage suspension type insulator. R-shaped metal pin. and a tapered metal pin having a tensile pin having a tensile strength of more than the breaking strength of insulating body are provided in porcelain insulating bodies, and a suspension insulator according to the present invention, a test for determining the tensile strength of the insulating body was made and the results. These insulators are designed and produced by using the computer analysis of mechanical and electrical stresses together with the technical know-how accumulated from long year of study into every respect of insulators.

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