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      • KCI등재

        Thermal Stress Measurement in Steel Plate Strengthened by CFRP and Aluminum Alloy Plates

        T. Ishikawa,H. Kawano,T. Nagao,A. Kobayashi 한국강구조학회 2016 International Journal of Steel Structures Vol.16 No.4

        In steel members strengthened by carbon-fiber reinforced polymer (CFRP) plates, the thermal stresses are introduced in the steel members, the CFRP plates and the adhesive layers when temperature changes because the linear thermal expansion coefficients of steel and CFRP are mismatched. As so far, the authors proposed a technique to reduce the thermal stress in steel members strengthened by CFRP plates, which involves bonding aluminum alloy plates with CFRP plates. In the proposed method, the thermal stress in steel member can be reduced so that there are negligible levels of stress in steel member when the cross sectional areas of CFRP and aluminum plates are designed to correspond to the coefficient of thermal expansion of steel, even though the thermal stresses are introduced in the CFRP and aluminum plates. In this study, to confirm the maintaining the thermal stress reduction in steel member by proposed method, thermal stress measurement in steel plate strengthened by CFRP and aluminum plates was carried out about 21 months. In this research, the thermal stress introduced in the steel plate strengthened by CFRP plates was also measured. Furthermore, to assume the thermal shear and normal (peel) stresses in adhesive layers, FE analysis with plane stress element was employed. As the result, it was shown the thermal stresses in steel plate with CFRP plate were able to calculate by using composite theory and measured temperature. Furthermore, in steel plate strengthened by CFRP and aluminum plates, the thermal stress introduced in steel plate was negligible-small through the all-season. It was found the thermal stresses in steel plate with CFRP plates as well as CFRP and aluminum plates were also estimated by using composite theory and measured temperature. In the steel plate strengthened by CFRP and aluminum plates, the thermal shear and normal stresses in adhesive layer glued to steel plate become smaller than that in the conventional CFRP bonded specimen. However, the shear stress in adhesive layers between CFRP and aluminum plates in proposed method was higher than the thermal stress in adhesive layers between CFRP plates in conventional method.

      • Major elements and noble gases of the Jinju (H5) meteorite, an observed fall on March 9, 2014, in South Korea

        Nagao, K.,Haba, M. K.,Lee, J. I.,Kim, T.,Lee, M. J.,Park, C.,Jwa, Y. J.,Choi, B.-G. THE GEOCHEMICAL SOCIETY OF JAPAN 2016 Geochemical journal Vol.50 No.4

        <P>The Jinju (H5) meteorite fell as four fragments in the Jinju area, Gyeonsangnam-do, South Korea, on March 9, 2014. The major element concentrations and noble gas isotopic compositions were determined for Jinju-1 and Jinju-2, stones of the first and second discoveries, respectively, by using X-ray fluorescence (XRF) analysis and noble gas mass spectrometry combined with total melting and stepwise heating noble gas extraction. The major element composition agrees well with that of equilibrated H chondrites. Very low contamination from terrestrial atmospheric noble gases was detected, which may be attributed to the rapid recovery of the stones within two days after the fall of the Jinju meteorite. A short cosmic ray exposure age of 2.4 My was obtained. The (U, Th)-He, and K-Ar ages are concordant at ca. 4.0 Gy, which suggests that no severe heating event occurred to cause a loss of He after the resetting at 4.0 Gy. Overabundances of trapped Ar and Kr, which were released at 800 degrees C, were found in addition to 'normal' Q gas of Ar, Kr and Xe at >= 1400 degrees C. The low-temperature component could be explained by Ar and Kr supplied by an adjacent impact region that were trapped when the minerals of the Jinju meteorite were formed during cooling. The heavy shock event that occurred at 4.0 Gy might have produced the observed numerous vugs and vapor growth crystals in this meteorite (Choi et al., 2015) and could have supplied the Ar and Kr to thermally weak minerals.</P>

      • SCIESCOPUSKCI등재

        Dietary Fatty Acid Supplementation during Transitional Period Increases Milk Production in Dairy Cows

        Nagao, K.,Takahara, Y.,Asai, H.,Hayashi, N.,Kitayama, T.,Yoshimura, Y.,Yokota, H.,Kita, Kazumi Asian Australasian Association of Animal Productio 2005 Animal Bioscience Vol.18 No.8

        The effect of dietary fatty acid supplementation on milk production, milk composition and plasma constituents in dairy cows was examined. Dietary fatty acids including mainly palmitic acid and stearic acid were given to cows from 2 weeks before and 8 weeks after parturition. Weekly gain of daily milk production was increased gradually during early lactation period and reached a plateau at 4 weeks after parturition. Weekly gain of daily milk production in lactating cows received dietary fatty acids was significantly higher than that of cows given a control diet alone. Although milk lactose concentration was slightly decreased by dietary fatty acid supplementation, milk fat and protein were not significantly influenced by dietary fatty acid supplementation. Dietary fatty acids did not affect plasma concentrations of triglyceride, non-esterified fatty acids, total cholesterol, high-density lipoprotein cholesterol and glucose during postpartum. It is suggested that dietary fatty acid supplementation has the potency to enhance energy balance and improve milk yield without any adverse effects on milk composition.

      • KCI등재후보

        초음속 노즐에서 발생하는 비대칭 유동의 제어에 관한 연구

        S. Matsuo,T. Setoguchi,T. Hashimoto,S. Tokuda,J. Nagao,김희동 한국가시화정보학회 2011 한국가시화정보학회지 Vol.9 No.2

        Several previous works on rocket nozzle flows have revealed the existence of the transition from FSS to RSS and the occurrence of asymmetric flow associated with the boundary layer separation, which can cause excessive side-loads of the propulsion system. Thus, it is of practical importance to investigate the asymmetric flow behaviors of the propulsion nozzle and to develop its control method. In the present study, the asymmetric flow control method using a cavity system was applied to supersonic nozzle flow. Time-dependent asymmetric flow was experimentally investigated with the rate of change of the nozzle pressure ratio. The results obtained showed that the cavity system installed on nozzle wall would be helpful in fixing the unsteady motions of the boundary layer separation, consequently reducing the possibility of the occurrence of the asymmetric flow.

      • SCISCIESCOPUS
      • SCIESCOPUSKCI등재

        Effects of Refeeding with a Protein-Free Diets Supplemented with Various Essential Amino Acids on the Plasma Insulin-Like Growth Factor-I Concentration in Fasting Young Chickens

        Kita, K,Shibata, T.,Nagao, K.,Hwangbo, J.,Okumura, J. Asian Australasian Association of Animal Productio 2002 Animal Bioscience Vol.15 No.3

        The effect of refeeding with various single essential amino acids on the recovery of plasma insulin-like growth factor-I (IGF-I) concentration in fasted young chickens was examined. Young chickens (29 days of age) were divided into 15 experimental groups. Chickens in one group were fed on the commercial diet ad libitum for 4 days. The remaining 56 chickens in 14 experimental groups were fasted. After 2 days of fasting, 52 chicks in 13 fasted groups were refed with one of the following experimental diets for 2 days. Eleven experimental diets were protein-free diets supplemented with one of 11 essential amino acids (Arg, Gly, His, Ileu, Leu, Met, Phe, Lys, Thr, Trp, Val). The remaining 2 experimental diets were a protein-free diet containing 11 essential amino acids and a protein-free diet not supplemented with amino acids. Birds in the remaining fasted group continued to be fasted for 2 days. Fasting for 2 days markedly reduced plasma IGF-I concentration. When fasted chickens were refed the protein-free diet containing either Gly alone or all essential amino acids, plasma IGF-I concentration was recovered to the level similar to that of fed chickens. Protein-free diet alone, however, failed to restore the reduced IGF-I concentration in plasma. Body weight loss modulated by feeding with protein-free diets supplemented with various single essential amino acids was associated with changes in plasma IGF-I concentrations. We concluded that body weight loss by feeding with a protein-free diet was lower than that of fasted chickens and that body weight loss associated with the decrease in plasma IGF-I concentration was modulated by feeding with protein-free diets containing various single essential amino acids.

      • SCIESCOPUSKCI등재

        Response of Muscle Protein Synthesis to the Infusion of Insulin-like Growth Factor-I and Fasting in Young Chickens

        Kita, K.,Shibata, T.,Aman Yaman, M.,Nagao, K.,Okumura, J. Asian Australasian Association of Animal Productio 2002 Animal Bioscience Vol.15 No.12

        In order to elucidate the physiological function of circulating IGF-I on muscle protein synthesis in the chicken under malnutritional conditions, we administrated recombinant chicken IGF-I using a osmotic mini pump to fasted young chickens and measured the rate of muscle protein synthesis and plasma metabolite. The pumps delivered IGF-I at the rate of $22{\mu}g/d\{300{\mu}g{\cdot}(kg\;body\;weight{\cdot}d)^{-1}\}$. Fractional rate of protein synthesis in the muscle was measured using a large dose injection of L-[$2,6-^3H$]phenylalanine. Constant infusion of chicken IGF-I did not affect plasma glucose level. Significant interaction between dietary treatment and IGF-I infusion was observed in plasma NEFA and total cholesterol concentrations. When chicks were fasted, IGF-I infusion decreased plasma NEFA and total cholesterol concentrations. On the other hand, IGF-I administration did not affect plasma levels of both metabolites. Fasting reduced plasma triglyceride concentration significantly. IGF-I infusion also decreased the level of plasma triglyceride. Plasma IGF-I concentration of young chickens was halved by fasting for 1 d. IGF-I infusion using an osmotic minipump for 1 d increased plasma IGF-I concentration in fasted chicks to the level of fed chicks. Fasting decreased body weight and the loss of body weight was significantly ameliorated by IGF-I infusion. There was a significant interaction between dietary treatment and IGF-I infusion in the fractional rate of breast muscle protein synthesis. There was no effect of IGF-I infusion on muscle protein synthesis in fed chicks. Muscle protein synthesis reduced by fasting was ameliorated by IGF-I infusion, but did not reach to the level of fed control. Muscle weight of fasted chicks infused with IGF-I was similar to fasted birds without IGF-I infusion, which suggests that muscle protein degradation would be increased by IGF-I infusion as well as protein synthesis in fasted chicks.

      • SCOPUSKCI등재

        Spin and Pseudo Spins in Theoretical Chemistry. A Unified View for Superposed and Entangled Quantum Systems

        Yamaguchi, Y.,Nakano, M.,Nagao, H.,Okumura, M.,Yamanaka, S.,Kawakami, T.,Yamaki, D.,Nishino, M.,Shigeta, Y.,Kitagawa, Y.,Takano, Y.,Takahata, M.,Takeda, R. Korean Chemical Society 2003 Bulletin of the Korean Chemical Society Vol.24 No.6

        A unified picture for magnetism, superconductivity, quantum optics and other properties of molecule-based materials has been presented on the basis of effective model Hamiltonians, where necessary parameter values have been determined by the first principle calculations of cluster models and/or band models. These properties of the matetials are qualitatively discussed on the basis of the spin and pseudo-spin Hamiltonian models, where several quantum operators are expressed by spin variables under the two level approximation. As an example, ab initio broken-symmetry DFT calculations are performed for cyclic magnetic ring constructed of 34 hydrogen atoms in order to obtain effective exchange integrals in the spin Hamiltonian model. The natural orbital analysis of the DFT solution was performed to obtain symmetry-adapted molecular orbitals and their occupation numbers. Several chemical indices such as information entropy and unpaired electron density were calculated on the basis of the occupation numbers to elucidate the spin and pair correlations, and bonding characteristic (kinetic correlation) of this mesoscopic magnetic ring. Both classical and quantum effects for spin alignments and singlet spin-pair formations are discussed on the basis of the true spin Hamiltonian model in detail. Quantum effects are also discussed in the case of superconductivity, atom optics and quantum optics based on the pseudo spin Hamiltonian models. The coherent and squeezed states of spins, atoms and quantum field are discussed to obtain a unified picture for correlation, coherence and decoherence in future materials. Implications of theoretical results are examined in relation to recent experiments on molecule-based materials and molecular design of future molecular soft materials in the intersection area between molecular and biomolecular materials.

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