• Title/Summary/Keyword: Energy Elasticity

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Study on the Tensile Strength of Oxidative Permanent Dyed Hair (산화형 영구 염모제로 처리한 모발의 인장강도 특성에 관한 연구)

  • Lee, Gui-Young;Chang, Byung-Soo
    • Applied Microscopy
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    • v.38 no.4
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    • pp.339-345
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    • 2008
  • In this study, we compared the stress and tensile strength of the hair treated with oxidative permanent dye with those of virgin hair. We investigated the fine structure of the hair section after the tensile test using scanning electron microscopy. The tensile strength of the virgin hair was measured as $14.66\;g/cm^2$, tensile energy was $108\;erg/cm^2$, and the maximum stress was 146.64g. Those of the dyed hair were $13.69\;g/cm^2$, $89.62\;erg/cm^2$ and 136.90 g, respectively. The differences in the tensile strength, the tensile energy and the maximum stress were $-0.97\;g/cm^2$, $-18.38\;erg/cm^2$, -9.74 g, respectively, which showed that the dyed hair had less elasticity and strength than the virgin hair. In the scanning electron microscopy investigation of the damaged hair after the tensile test, lift-off of the cuticle outer layer were shown in both virgin hair and dyed hair, which was more severe in the dyed hair than the virgin hair. Adjacent cuticular cells of the cuticle layer were separated by the destruction of intercellular membrane complex. The macrofibrils were exposed and separated from the cortex torn by tensile strength.

An Accurate and Efficient Analysis of Composite Plates Based on Enhanced First-order Shear Deformation Theory (개선된 일차전단변형이론을 이용한 복합재료 적층평판의 고정밀 해석)

  • Kim, Jun-Sik;Cho, Maeng-Hyo
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.19 no.4 s.74
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    • pp.407-418
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    • 2006
  • In this paper, an efficient yet accurate stress analysis based on the first-order shear deformation theory (FSDT) is presented. The transverse shear strain energy is modified via the mixed variational theorem, so that the shear correction factors are automatically involved in the formulation. In the mixed variational formulation, the transverse stresses are taken to be functions subject to variations. The transverse shear stresses based on an efficient higher order plate theory (EHOPT, Cho and Parmerter, 1993) are utilized and modified, while the transverse normal stress is assumed to be the third-order polynomial of thickness coordinates, which satisfies both zero transverse shear stresses and prescribed surface fractions in top and bottom surfaces. On the other hand, the displacements are assumed to be those of the FSDT Resulting strain energy expressions are referred to as an EFSDTM3D that stands for an enhanced first-order shear deformation theory based on the mixed formulation for three dimensional elasticity, The developed EFSDTM3D preserves the computational advantage of the classical FSDT while allowing for important local through-the-thickness variations of displacements and stresses through the recovery procedure that is based on the least square minimization of in-plane stresses. Comparisons of displacements and stresses of both laminated and sandwich plates using the present theory are made with the classical FSDT, three-dimensional exact solutions, and available data in the literature.

On the Effective Shear Rigidity in Ship Vibration Analysis (선체진동해석(船體振動解析)에 있어서의 유효전단강성도(有效剪斷剛性度))

  • K.C.,Kim;S.H.,Choi
    • Bulletin of the Society of Naval Architects of Korea
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    • v.22 no.1
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    • pp.45-53
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    • 1985
  • For the analysis of vertical vibrations of a ship's hull, the Timoshenko beam analogy is accepted up to seven or eight-node modes provided that the system parameters are properly calculated. As to the shear coefficient, it has been a common practice to apply the strain energy method or the projected area method. The theoretical objection to the former is that it ignores lateral contraction due to Poisson's ratio, and the latter is of extreme simplifications. Recently, Cowper's and Stephen's shear coefficient formulas have drawn ship vibration analysts' attentions because these formulas, derivation of which are based on an integrations of the equations of three-dimensional elasticity, take Poisson's ratio into account. Providing computer programs for calculation of the shear coefficient of ship sections modeled as thin-walked multicell sections by each of the forementioned methods, the authors calculated natural vibration characteristics of a bulk carrier and of a container ship by the transfer matrix method using shear coefficients obtained by each of the methods, and discussed the results in comparision. The major conclusions resulted from this investigation are as follows: (1) The shear coefficients taking account of the effects of Poisson's ratio, Cowper's $K_c$ and Stephen's $K_s$, result in higher values of about 10% in maximum as compared with the shear coefficient $K_o$ based on the conventional strain energy methods; (a) $K_c/K_o{\cong}1.05\;and\;K_s/K_o{\cong}1.10$ for ships having single skin side-shell such as a bulk carrier. (b) $K_c/K_o{\cong}1.02\;and\;K_s/K_o{\cong}1.05$ for ships having longitudinally through bulkheads and/or double side-shells in the portion of the cargo hod such as a container carrier. (2) The distributions of the effective shear area along the ship's hull based on each of $K_o,\;K_c\;and\;K_s$ are similar each another except the both end portions. (3) Natural frequencies and mode shapes of the hull based on each of $K_c\;and\;K_s$ are of small differences as compared each other. (4) In cases of using $K_c\;or\;K_s$ in ship vibration analysis, it is also desirable to have the bending rigidity be corrected according to the effective breadth concept. And then, natural frequencies and mode shapes calculated with the bending rigidity corrected in the above and with each of $K_o,\;K_c\;and\;K_s$ result in small differences as compared each another. (5) Referring to those mentioned in the above (3) and (4) and to the full-scale experimental results reported by Asmussen et al.[17], and considering laboursome to prepare the computer input data, the following suggestions can safely be made; (a) Use of $K_o$ in ship vibration analysis is appropriate in practical senses. (b) Use of $K_c$ is appropriate even for detailed vibration analysis of a ship's hull. (6) The effective shear area based on the projected area method is acceptable for the two-node mode.

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Hydraulic-Thermal-Mechanical Properties and Radionuclide Release-Retarding Capacity of Kyungju Bentonite (경주 벤토나이트의 수리-열-역학적 특성 및 핵종 유출 저지능)

  • Jae-Owan Lee;Won-Jin Cho;Pil-Soo Hahn
    • Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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    • v.2 no.2
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    • pp.87-96
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    • 2004
  • Studies were conducted to select the candidate buffer material for a high-level waste (HLW) repository in Korea. This paper presents the hydraulic properties, the swelling properties, the thermal properties, and the mechanical properties as well as the radionuclide release-retarding capacity of Kyungju bentonite as part of those studies. Experimental results showed that the hydraulic conductivities of the compacted bentonite were very low and less than $10^{-11}$m/s. The values decreased with increasing the dry density of the compacted bentonite. The swelling pressures were in the range of 0.66 MPa to 14.4 ㎫ and they increased with increasing the dry density. The thermal conductivities were in the range of 0.80 ㎉/m $h^{\circ}C$ to 1.52 ㎉/m $h^{\circ}C$. The unconfined compressive strength, Young's modulus and Poison's ratio showed the range of 0.55 ㎫ to 8.83 ㎫, 59 ㎫ to 1275 ㎫, and 0.05 to 0.20, respectively, when the dry densities of the compacted bentonite were 1.4 Ms/㎥ to 1.8 Mg/㎥. The diffusion coefficients in the compacted bentonite were measured under an oxidizing condition. The values were $1.7{\times}10^{-10}$m^2$/s to 3.4{\times}10^{-10}$m^2$/s for electrically neutral tritium (H-3), 8.6{\times}10^{-14}$m^2$/s to 1.3{\times}10^{-12}$m^2$/s for cations (Cs, Sr, Ni), 1.2{\times}10^{-11}$m^2$/s to 9.5{\times}10^{-11}$m^2$/s for anions (I, Tc), and 3.0{\times}10^{-14} $m^2$/s to 1.8{\times}10^{-13}$m^2$/s $for actinides (U, Am), when tile dry densities were in the range of 1.2 Mg/㎥ to 1.8 Mg/㎥. The obtained results will be used in assessing the barrier properties of Kyungju bentonite as a buffer material of a repository in Korea.n Korea.

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The Effect of $Sa-Am$ Lung Sedating Acupuncture on Wrist Pulse in Healthy Human Subjects (폐승격(肺勝格) 자침이 촌관척(寸關尺) 맥파변화에 미치는 영향)

  • Kim, Seok-Joo;Lee, Hyun
    • Journal of Acupuncture Research
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    • v.29 no.2
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    • pp.43-57
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    • 2012
  • Objectives : The purpose of this study is to observe the effects of $Sa-Am$ lung sedating acupuncture (LS) on wrist pulse changes in healthy participants. Method : Forty healthy subjects participated in this study, and were divided into an acupuncture group and controlled group. Using a three-dimensional pulse imaging system (DMP-3000), wrist pulse was measured before, immediately after, 30 minutes after and 60 minutes after acupuncture in the acupuncture group, with the rest in controlled group. Sixteen parameters between the acupuncture group and the controlled group were analyzed at Cun, Guan and Chi in each time. Result : After LS acupuncture, wrist pulse sixteen parameters were changed significantly according to the time at each measuring region. 1. Heart rate significantly decreased in immediately after, 30 minutes after and 60 minutes after, Pulse period significantly increased in 30 minutes after and 60 minutes after. 2. T4 didn't significantly changed, T-T4 significantly increased in immediately after, 30 minutes after and 60 minutes after. T4/T, T4/(T-T4), T1/T, T5/T significantly decreased in immediately after, 30 minutes after and 60 minutes after. (T-T4)/T significantly decreased in immediately after, 30 minutes after and 60 minutes after. T5 significantly increased in 30 minutes after and 60 minutes after. 3. Modulus of elasticity significantly decreased in left Cun 60 minutes after, significantly increased in left Chi 30 minutes after. 4. Variance of Amplitude significantly increased in right Guan 60 minutes after. 5. Area of pulse significantly increased in left Cun 60 minutes after, left Chi 30 minutes after and right Cun 60 minutes after. Systolic pulse area significantly decreased left Chi 30 minutes after, right Cun immediately after, 30 minutes after and 60 minutes after, right Guan in immediately after. 6. Energy/min significantly decreased in left Chi 60 minutes after and right Cun immediately after. EIx significantly decreased in right Cun immediately after. 7. In both sides Cun, Guan, Chi wrist pulse, a lot of significant changes in right Cun and left Chi appeared, and then followed by the left Cun, right Guan. Conclusion : This study analyzed that the correlation between LS acupuncture and radial pulse(cun, guan, chi) is considered to be meaningful, hereafter clinical studies on this are needed.

The Fractural-Mechanical Properties and Durability of Lightweight Concrete Using the Synthetic Lightweight Aggregate (합성경량골재(SLA)를 사용한 경량콘크리트의 파괴, 역학적 특성 및 내구성)

  • Jo Byung-Wan;Park Seung-Kook;Park Jong-Bin;Daniel C. Jansen
    • Journal of the Korea Concrete Institute
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    • v.17 no.1 s.85
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    • pp.19-25
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    • 2005
  • Recycling of waste materials in the construction Industry is a useful method that can cope with an environment restriction of every country. In this study, synthetic lightweight aggregates are manufactured with recycled plastic and fly ash with 12 percent carbon. Nominal maximum-size aggregates of 9.5 mm were produced with fly ash contents of 0, 35, and $80\%$ by the total mass of the aggregate. An expanded clay lightweight aggregate and a normal-weight aggregate were used as comparison. Gradation, density, and absorption capacity are reported for the aggregates. Five batches of concrete were made with the different coarse aggregate types. Mechanical properties of the concrete were determined including density, compressive strength, elastic modulus, splitting tensile strength, fracture toughness, and fracture energy. Salt-scaling resistance, a concrete durability property, was also examined. Compressive and tensile strengths were lower for the synthetic aggregates; however, comparable fracture properties were obtained. Relatively low compressive modulus of elasticity was found for concretes with the synthetic lightweight aggregate, although high ductility was also obtained. As nv ash content of the synthetic lightweight aggregate increased, all properties of the concrete were improved. Excellent salt-scaling resistance was obtained with the synthetic lightweight aggregate containing 80 percent fly ash.

Radiation Damage Mechanism of the Small Intestine's Absorptive Epithelium and Radioprotection Effect after Propolis Abdominal Cavity Injection (프로폴리스 복강 주사 후 소장 흡수상피조직의 방사선 손상 기전과 방어효과)

  • Ji, Tae-Jeong;Lee, Sang-Hun
    • The Journal of the Korea Contents Association
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    • v.10 no.7
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    • pp.297-304
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    • 2010
  • As Small Intestine Absorptive Epithelium Cells are surrounded by mucus polysaccharide and lymphocytes and mitochondria, they are sensitive to radiation energy. Damaged cells lead to a deficiency of nutrients and the imbalance of electrolyte metabolism, which in turn can becomes a major cause of an intestine tract death. This research observed ultra structures after injecting propolis into the abdominal cavity in order to reveal the radiation damage mechanism and radioprotection effect of intestine absorptive epithelium cells. The result of this research's observation found that stenosis occurred in the small intestine in some tissues 20 days after 5Gy irradiation, their surface turned black, and their elasticity dropped. Through observation with an optical microscope, it was found that the size of the goblet cells decreased, while the paneth granulate cells atrophied and were vacuolated. Observation with an transmission electron microscope(TEM) revealed that while microvill and lysosome were normally observed in jejunum tissues, mitochondria membrane was damaged and uneven surfaces were formed on lymphocytes. The membrane of absorptive epithelium cells hypertrophied in tissues of the ileum, and vacuole was observed. However, the observation after injecting propolis into the abdominal cavity found that mitochondria damage dropped dramatically, and radioprotection effects were to some extent confirmed, considering that glycocalyx of villi was clear, and M cells could be observed.

An Analytical Study on the Buckling of Orthotropic Plates and Local Buckling of Compression Members (직교이방성 판의 좌굴 및 압축재의 국부좌굴에 대한 해석적 연구)

  • Choi, Jin-Woo;Lee, Kang-Yeon;Park, Jung-Hwan;Yoon, Soon-Jong
    • Journal of the Korean Society for Advanced Composite Structures
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    • v.3 no.1
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    • pp.21-28
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    • 2012
  • In this paper, we present the analytical study results pertaining to the buckling of the orthotropic plates and local buckling of structural compression members composed of orthotropic plate components. Fiber reinforced polymeric plastic (FRP) materials, have many advantages over conventional structural materials such as steel and concrete. The advantages of the FRP materials are high specific strength and stiffness, high corrosion resistance, right weight, etc. Among the various manufacturing methods, pultrusion process is one of the best choices for the mass production of structural plastic members. Since the major reinforcing fibers are placed along the axial direction of the member, this material is usually considered as an orthotropic (tranversely isotropic, more specifically) material. However, pultruded fiber reinforced plastic structural members have low modulus of elasticity and are composed of orthotropic thin plate components the members are prone to buckle. Therefore, stability is an important issue in the design of the pultruded FRP structural members. In this paper, the buckling of orthotropic plates and the local buckling of pultruded FRP structural members are investigated by following the previous research results and the local buckling strength of the member produced in the domestic manufacturer is found.

Mechanical Characteristics of Recycled PET Polymer Concrete with Demolished Concrete Aggregates (PET와 재생골재를 이용한 폴리머콘크리트의 역학적 특성)

  • Jo Byung-Wan;Lee Du-Wha;Park Seung-Kook
    • Journal of the Korea Concrete Institute
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    • v.17 no.3 s.87
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    • pp.335-342
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    • 2005
  • In this paper, fundamental properties of Polymer Concrete(PC), made from unsaturated polyester resin based on recycled PET and recycled aggregate were investigated. Mechanical properties include strength, modulus of elasticity, and chemical resistance. Resins based on recycled PET and recycled aggregate offer the possibility of low source cost for forming useful products, and would also help alleviate an environmental problem and save energy. The results of test for resin contents and recycled aggregate ratio we, first, the strength of Polymer Concrete made with resin based on recycled PET and recycled aggregate increases with resin contents relatively, however beyond a certain resin contents the strength does not change appreciably, Second, the relationship between the compressive strength and recycled aggregate ratio at resin $9\%$ has a close correlation linearly whereas there is no correlation between the compressive strength and the flexural strength of RPC with recycled aggregate ratio. Third, the effect of acid resistance at resin $9\%$ was found to be nearly unaffected by HCI, whereas the PC with $100\%$ recycled aggregate showed poor acid resistance. Unlike acid, alkali nearly does not seem to attack the RPC as is evident from the weight change and compressive strength. And last, In case of stress-strain curve of polymer concrete with $100\%$ of natural aggregate and $100\%$ recycled aggregate it is observed the exceptional behavior resulting in different failure mechanisms of the material under compression.

Is Compact Urban Spatial Structure Effective for Public Transportation Mode? (컴팩트형 공간구조가 대중교통수단의 이용활성화에 보다 효과적인가?)

  • Lee, Jae-Yeong;Kim, Hyung-Chul
    • Journal of Korean Society of Transportation
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    • v.22 no.3 s.74
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    • pp.7-16
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    • 2004
  • The purpose of this study was to find the characteristics of travel behavior and accessibility in terms of spatial structure. We analyzed travel behaviors and accessibility using a mode choice model and the Complementary Accessibility Index(CAI). The urban spatial structures that were compared were a compact city (CC) versus a sprawled city (SC), and high residential density districts (HD) versus low residential density districts (LD). First, CC and HDs residents had a shorter commuting distance than the CC and LDs residents. Second, behavior models showed that the use of Private cars for commuting in SCs was found to be greater than private car use in CCs, and that public transportation modes would be encouraged in CCs. Third, changes associated with the time and cost of commuting by private car generally affect the demand for public transportation modes in the CC. Also, analysis of cross elasticity suggests that changes of subway travel time affect the demand for buses very elastically. Fourth, the CAI of SC and LD were superior to the CC and HD even though the SC inefficient urban forms in terms of spatial structure. So, the spatial distribution of population density was also found to be an important factor affecting accessibility and energy savings.