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Influence of Biaxial Loads on Impact Fracture of High-Strength Membrane Materials
Kumazawa, Hisashi,Susuki, Ippei,Hasegawa, Osamu,Kasano, Hideaki The Korean Society for Composite Materials 2009 Advanced composite materials Vol.18 No.4
Impact tests on high-strength membrane materials under biaxial loads were experimentally conducted in order to evaluate influence of biaxial loads on impact fracture of the membrane materials for the inflated applications. Cruciform specimens of the membrane materials were fabricated for applying biaxial loadings during the impact test. A steel ball was shot using a compressed nitrogen gas gun, and struck the membrane specimen. Impact tests on uniaxial strip specimens were also conducted to obtain the effect of specimen configuration and boundary condition on the impact fracture. The results of the measured crack length and the ultra-high speed photographs indicate the impact fracture properties of the membrane fabrics under biaxial loadings. Crack length due to the impact increased with applied tensile load, and the impact damages of the cruciform membrane materials under biaxial loadings were smaller than those of under uniaxial loadings. Impact fracture of the strip specimen was more severe than that of the cruciform specimen due to the difference of boundary conditions.
Hypoxia Tolerance Evaluation of Red Leaf Lettuce by Expression Analysis of LsADH Gene
( Mana Kumazawa ),( Manasikan Thammawong ),( Hushna Ara Naznin ),( Kohei Nakano ) 한국농업기계학회 2018 한국농업기계학회 학술발표논문집 Vol.23 No.1
The aim of this study was to evaluate the hypoxia tolerance of fresh produce by gene expression analysis. An alcohol dehydrogenase-encoding gene (ADH), which is a key factor determining anaerobic metabolism, was analyzed in red leaf lettuce stored at 25 ºC under various O<sub>2</sub> conditions. LsADH expression of samples stored under 15%, 10% and 3.5% O<sub>2</sub> condition was detected about 6 times higher than the control (20.9%), and it was remarkably increased by 12 times when stored under 2% O<sub>2</sub>. On the other hand, the respiratory quotient breakpoint (RQB) was determined as 0.3% because RQ was mostly stable at around 1.1 under the O<sub>2</sub> level ranged from 20.9% to 0.3%, and notably increased at below 0.3%. The fermentation threshold (FT) was found as 1% because ethanol and acetaldehyde were remarkably accumulated at below 1%O<sub>2</sub>. In this study, 2% O<sub>2</sub> at which the relative gene expression level of LsADH increased markedly was considered as the gene expression breakpoint (GEB). From this fact, the ‘low O<sub>2</sub> limit’, estimated based on GEB is relatively higher and more sensitive compared to RQB and FT methods. GEB is thought to be a useful indicator in determining the appropriate O<sub>2</sub> concentration for storing fresh produce.
Hidehiro Kumazawa,Um, Myeong Heon,Lee, Chul Tae 한국공업화학회 1997 Journal of Industrial and Engineering Chemistry Vol.3 No.4
BaTiO₃ fine particles with perovskite structure were synthesized using amorphous TiO₂ at temperatures as low as 300℃ by hydrothermal method. Barium hydroxide and titanium tetraethoxide were used as starting materials. The relationship between the specific dielectric constant of sintered disks and the mean size of synthesized particles has been investigated. The mean size of the BaTiO₃ particles synthesized by hydrothermal reaction for 4 hours was nearly 0.047㎛ while the barium-to-titanium (BT) molar ratio ≥1.2. The specific dielectric constants of sintered BaTiO₃ disks exceeded 6000 with the particle size of 0.10-0.17㎛. It was speculated that the particle size of resulting disks would considerably affect the specific dielectric constant of resulting disks.
Unsteady-State Absorption of CO_2,into w/o Emulsion with Aqueous Alkaline Liquid Droplets
Park, Sang-Wook,Kumazawa, Hidehiro,Sohn, In-Joe 한국화학공학회 2002 Korean Journal of Chemical Engineering Vol.19 No.1
Unsteady-state absorption of CO_2 into w/o emulsion was studied by experimental measurements and prediction from mathematical modeling. Absorption experiments were performed by using a stirred vessel with a flat gasliquid interface under 0.101 MPa and 25℃. Continuous phase was benzene that has larger solubility than water. Dispersed phase was an aqueous solution of NaOH and AMP. The effects of reactant concentration, size of emulsified droplets, volume fraction of continuous phase and stirring speed on the absorption rate of CO_2 were investigated. In the mathematical model, the mechanism of CO_2 absorption into the continuous phase through a gas-liquid interface was described on the basis of the penetration model, while the subsequent absorption/reaction in the dispersed aqueous droplets was modeled by the film model.
GAS ABSORPTION OF CARBON DIOXIDE IN A HOLLOW FIBER CONTAINED LIQUID MEMBRANE ABSORBER
Park, Sang Wook,Kumazawa, Hidehiro,Suh, Dong Soo,Hwang, Kyoung Son 한국화학공학회 1997 Korean Journal of Chemical Engineering Vol.14 No.4
Experiments on the absorption of CO₂ into a hollow fiber contained liquid membrane absorber were performed. The feed gas was a mixture of CO₂ and N₂, absorbent liquid was 2-amino-2-methyl-l-propanol and the hollow fiber was a microporous hydrophobic polytetrafluoroethylene membrane. Outlet concentration of CO₂from the absorber decreased as absorbent concentration increased, gas flow rate increased and were held constant for speed of agitation, but had a maximum value in the range of inlet concentration of CO₂from 5 to 40 mole %. The reaction rate constant obtained for CO₂-amine system was 231 ℓ/㏖·s at 25℃ using a flat stirred vessel, and the membrane-side-mass-transfer coefficient was 1.217 x 10^(-5) ㏖/㎠·s·atm in CO₂/N₂-amine system. A diffusion model based on mass transfer with fast-reaction was proposed to predict the performance of the absorber.