• International Journal of Precision Engineering and Manufacturing
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• v.1 no.1
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• pp.91-97
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• 2000

Anisotropic work hardening of cold rolled low carbon steel sheets is studied. The experiments consist of two stage tensile prestraining and tensile tests. At the first prestraining, steel sheets are streteched along the rolling direction by 3% and 6% tensile strains. The second prestrains are at 0${\cric}$, 30${\cric}$, 60${\cric}$to the rolling directions by varying degrees. Tensile tests are performed on the specimens cut from the sheets after the two stage prestraining. A theoretical framework on anisotropic hardening is proposed which includes Hill's quadratic yield function, ziegler's kinematic hardening rule, and Kim and Yin's assumption on the rotation of orthotropy axes. The predicted variations of R-values with second stage tensile strain are compared with the experimental data.

• Journal of Microbiology and Biotechnology
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• v.9 no.2
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• pp.219-222
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• 1999

A simple sequence of membrane concentration and DEAE-Cellulose chromatography has been optimized to give a purified dextransucrase from Leuconostoc mesenteroides B-512FMCM with the highest specific activity (248.8 IU/mg protein) ever reported in high yield (overall 88.7%) for dextransucrase. When there was no sucrose in the dextransucrase and the dextran reaction digest, the dextransucrase hydrolyzed glucose from dextran. The glucose was transferred to the other glucoses from dextran and formed isomaltose and isomaltodextrin. The transglycosylation efficiency of glucose from dextran was much higher with acceptors. The dextransucrase can be used for the production of various kinds (or structures) of oligosaccharides using dextran and various acceptors with almost 100% theoretical yield.

• Tribology and Lubricants
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• v.19 no.6
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• pp.349-356
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• 2003

A damper floating ring seal with round hole pattern surfaces is suggested for better leakage control. The flat plate test of the round hole pattern surfaces has been performed to yield an empirical friction factor model. The exact predictions of the lock­up position of the damper floating ring, the leakage performance, and the rotordynamic coefficients of the seal are necessary to evaluate the rotordynamic performance of the turbo pump unit. The governing equations including the empirical friction factor model for round hole pattern surfaces are solved by the Fast Fourier Transform method. The lock­up position, leakage flow rate, and rotordynamic coefficients are evaluated according to the geometric parameters of the damper floating ring seal. Theoretical results show that the damper floating ring seals yield less leakage and better rotordynamic stability than the floating ring seal with a smooth surface.

• 한국생물공학회:학술대회논문집
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• 2000.11a
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• pp.665-668
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• 2000

Recombinant Escherichia coli NZN111 ($F-{\Delta}pfl::Cam$ ldhA::Kan) harboring pTrcML, a plasmid containing the E. coli malic enzyme gene, produced considerable amount of malic acid along with the desired product succinic acid. This seemed to be due to the unmatched redox states between glucose and succinic acid. Therefore, a more reduced carbon substrate sorbitol was examined for the possibility of matching the potential during succinic acid production. When NZN111 (pTrcML) was cultured in LB medium containing 20 g/L sorbitol under $CO_2$ atmosphere, 10 g/L of succinic acid was produced. The apparent yield of succinic acid was 1.1 g succinic acid per g sorbitol, which is 85% of the maximum theoretical yield.

• Proceedings of the KSME Conference
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• 2001.11a
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• pp.746-752
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• 2001

Design sensitivity analysis for nonlinear structural problems has been emerged in the last decade as a glowing area of engineering research. As a result, theoretical formulations and computational algorithms have already developed for design sensitivity of nonlinear structural problems. There is not enough research for practical nonlinear problems using multi-element, due to difficulties of implementation into FEA. Therefore, nonlinear response analysis for stiffened shell which consists of Mindlin plate and Timoshenko beam, was considered. Specially, it presents the backward-Euler method which is adopted to describe an exact yield state in the stress computation procedure. Then, design sensitivity analysis of nonlinear structures, particularly elasto-perfectly-plastic structure, is developed using direct differentiation method. The accuracy of the developed sensitivity analysis was compared with the central finite difference method. Finally, on the basis of above results, design improvement for stiffened shell is suggested.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2000.04a
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• pp.17-20
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• 2000

Polymeric foams are excellent energy absorber and have found a wide range of applications especially in the automotive industry. The purpose of the present study is to develop experimental and theoretical methodology to characterize the pressure dependent yield behavior of polymeric foams. For the compression test in a triaxial stress sate a specially designed device was placed in a press machine to produce and control oil pressure. From the experiment results it was observed that the size of Mother circles is changed with mean normal stress in contrast to general metal. Then the Coulomb-Mohr criterion was applied to the data.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.29 no.8 s.239
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• pp.1139-1145
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• 2005

Most failures of ductile materials in metal forming processes occurred due to material damage evolution - void nucleation, growth and coalescence. In this paper, the modified yield function of Liao et al in conjunction with the Hosford's yield criterion is studied to clarify the plastic deformation characteristic of voided anisotropic sheet metals. The void growth of an anisotropic sheet under biaxial tensile loading and damage effect of void growth on forming limits of sheet metals are investigated. Also the characteristic length defining the neck geometry is introduced in M-K model to incorporate the effect of triaxial stress in necked region on forming limits. The forming limits theoretically predicted are compared with experimental data. Satisfactory agreement was obtained between the predictions and experimental data.

• Journal of Applied Biological Chemistry
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• v.63 no.3
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• pp.197-201
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• 2020

In order to enhance the extraction efficiency of flavonoid from Saururus chinensis, carbohydrate-hydrolyzing enzyme Viscozyme L aided extraction techniques have been studied. Then flavonoid composition, as well as quercetin, were also identified using UV/Vis, HPLC/MS, and ¹H-NMR. The results showed that favorable extraction conditions were Viscozyme L concentration of 0.25 mg/g, pH 4.2, reaction at 45 ℃ for 12 h. Under the favorable extraction condition, total flavonoid yield (37.9 mg/g) and quercetin yield (0.86 mg/g) increased by about 2.0 and 9.6 times, respectively, compared to control group. Interestingly, as a significant flavonoid of S. chinensis, flavonoid glycones rutin was hydrolyzed to aglycones quercetin by Viscozyme L. These findings provide scientific and theoretical support for the development quercetin-rich products, which was quickly absorbed by the human body than rutin.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.09a
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• pp.3-26
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• 2009

Superloading yield surface concept is newly introduced together with subloading yield surface conception in order to describe full gradation continuously of the mechanical behavior of soils from typical sand through intermediate soil to typical clay (All Soils). Finite deformation theory has been applied to the soil skeleton-pore water coupled continuum mechanics, which enables us to discuss things in a perpetual stream from stable state to unstable state like from deformation to failure and vice versa like from liquefaction to post liquefaction consolidation of sand (All States). Incremental form of the equation of motion has been employed in the continuum mechanics in order to incorporate a rate type constitutive equation, which is "All Round" enough to predict ground behavior under both static and dynamic conditions. The present paper is the shortened version of the lecture note delivered in 2008 Theoretical and Applied Mechanics Conference, Science Council Japan, but with newly developed application examples.

• KSBB Journal
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• v.9 no.2
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• pp.104-107
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• 1994

A cone-type tower fermentor packed with Sacchromyces uvarum was employed to examine the continuous ethanol fermentation process. The maximum yeast concentration in the cone-type tower fermentor was 37.5-39.5g/$\ell$, the maximum ethanol productivity at the dilution rate of $hr^{-1}$ was 16.3g/$\ell$ . hr and the average ethanol yield was 0.48g EtOH/g glucose, which was 94% of the maximum theoretical yield. It was concluded that a cone-type tower fermentor might offer better perspectives for continuous ethanol fermentation.