• Structural Engineering and Mechanics
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• v.56 no.6
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• pp.917-938
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• 2015

The nonlinear numerical analysis of the impact response of reinforced concrete/mortar beam incorporated with the updated Lagrangian method, namely the Smoothed Particle Hydrodynamics (SPH) is carried out in this study. The analysis includes the simulation of the effects of high mass low velocity impact load falling on beam structures. Three material models to describe the localized failure of structural elements are: (1) linear pressure-sensitive yield criteria (Drucker-Prager type) in the pre-peak regime for the concrete/mortar meanwhile, the shear strain energy criterion (Von Mises) is applied for the steel reinforcement (2) nonlinear hardening law by means of modified linear Drucker-Prager envelope by employing the plane cap surface to simulate the irreversible plastic behavior of concrete/mortar (3) implementation of linear and nonlinear softening in tension and compression regions, respectively, to express the complex behavior of concrete material during short time loading condition. Validation upon existing experimental test results is conducted, from which the impact behavior of concrete beams are best described using the SPH model adopting an average velocity and erosion algorithm, where instability in terms of numerical fragmentation is reduced considerably.

• Journal of the Earthquake Engineering Society of Korea
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• v.21 no.5
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• pp.205-213
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• 2017

The WUF-W moment connection is a pre-qualified connection that can be used for special moment frames specified in current seismic design specifications. Since the stress distribution near the connection varies according to access hole configuration, the cyclic performance of WUF-W connections is strongly affected by the access hole configurations. To evaluate the connection performance according to various access hole configurations, it is expensive to conduct experiments with many connection specimens. Instead, finite element analyses (FEA) can be performed. Throughout the FEA, stress and strain distribution in the connection can be monitored at each loading step. The purpose of this study is to construct nonlinear 3-dimensional FE models for accurately predicting the cyclic behavior of WUF-W connections. For predicting connection fracture using FEA, an appropriate response index detecting the incidence of connection rupture is proposed.

• Journal of Applied Biological Chemistry
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• v.57 no.2
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• pp.183-188
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• 2014

In order to increase the nutritional quality of soybean meal (SBM) as an animal feed, Bacillus subtilis TP6, a previously isolated strain from an Indonesian traditional fermented soybean food, Tempeh, was used as a starter organism for solid-state fermentation. In the pre-treated SBM with water content of 60% (v/w), B. subtilis TP6 was grown to a maximum viable cell number of $3.5{\times}10^9CFU/g$. Compared to control, crude protein in Bacillus fermented SBM was increased by 16%, while raffinose, stachyose, and trypsin inhibitors were reduced by 31, 37, and 90%, respectively. The Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis showed that proteins in the fermented SBM were remarkably hydrolyzed into smaller molecular masses, resulting in a decrease in large sized proteins. Our data suggested that B. subtilis fermentation could increase the nutritive value of SBM through reduction of anti-nutritive factors and improvement of protein quality by hydrolysis of soy protein. In addition, B. subtilis TP6 produced a functional ingredient, poly-${\gamma}$-glutamic acid which has various health benefits.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.10a
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• pp.244-247
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• 2005

Although several artificial disc designs have been developed for the treatment of discogenic low back pain and used clinically, biomechanical change with its implantation seldom studied. To evaluate the effect of artificial disc implantation on the biomechanics of lumbar spinal unit, nonlinear three-dimensional finite element model of L1-L5, S1 was developed and strain and stress of vertebral body and surrounding spinal ligaments were predicted. Intact osteoligamentous L1-L5, S1 model was created with 1-mm CT scan of a volunteer and known material property of each element were applied. This model also includes the effect of local muscles which was modeled with pre-strained spring elements. The intact model was validated with reported biomechanical data. Two models implanted with artificial discs, SB Charite or Prodisc, at L4/5 via anterior approach were also developed. The implanted model predictions were compared with that of intact model. Angular motion of vertebral body, force on spinal ligaments, facet joint contact force with $2\sim12$ Nm flexion-extension moment.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.16 no.6 s.111
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• pp.602-608
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• 2006

In order to evaluate performance of anti-vibration gloves, it is necessary to measure the transmitted vibration to the hand and the applied forces at the same time while gripping the vibrating handle. In the study a system was developed to measure both the vibration and the forces. The system consists of a measurement handle with eight strain gauges and two accelerometers and a PC-based system with a software for signal processing and evaluation of the hand-transmitted vibration and for control of applied forces in the pre-determined range. The handle was installed on the vibration shaker which is strong enough so as not to be affected by dynamic coupling with the hand-arm system. Whole procedure of ISO 10819 to determine the vibration transmissibility of anti-vibration gloves was programmed into the system. As an example of the application, three subjects joined the test to get vibration transmissibilities of anti-vibration gloves where each glove was tested twice a subject. Average and standard deviation of vibration transmissibility were also calculated.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.11a
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• pp.689-694
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• 2004

To increase accurateness and reliability of the evaluation of power tool vibration transmitted to an operator, it is necessary to measure grip and feed forces during the measurement of hand-transmitted vibration. In the study a system was invented to measure the vibration and the grip and/or feed force, which consists of a measurement handle and a PC with data acquisition system and the software. Strain gauges and an accelerometer were mounted on the handle for the simultaneous measurement of the forces and the vibration. The program in the system makes it possible to monitor the grip and feed force during the tool operation so that the operator keeps the applying forces within the pre-determined range. Investigating the vibration total values, frequency-weighted root mean square accelerations at the handle, obtained at various conditions with control of the grip and feed force showed more consistency than those measured without force control. By using the system the experimenter can reduce uncertainty of the measured vibration.

• Preventive Nutrition and Food Science
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• v.1 no.1
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• pp.121-126
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• 1996

A bacterial strain LC-413, producing extracellular inulin fructotransferase which converts inulin into di-D-fructofuranose dianhydride(DFAIII) and amount of oilgosaccharides, was isolated from soil and pre-sumed as Flavobacteium sp. LC-413. The enzyme production was induced by inulin as carbon source and enhanced by the addition of 0.3% malt extract and 0.2% {TEX}$NaNO_{3}${/TEX} as nitrogen source. The enzyme activity in the culture supernatant reached at the maximum, 78.6units/ml, after 11 hours of cultivation in the medium composition of 1.5% inulin, 0.2% {TEX}$NaNO_{3}${/TEX}, 0.05% {TEX}$K_{2}${/TEX}{TEX}$HPO_{4}${/TEX}, 0.05% {TEX}$MgSO_{4}${/TEX}.7{TEX}$H_{2}${/TEX}O, 0.05% KCI, a trace amount of {TEX}$FeSO_{4}${/TEX}.7{TEX}$H_{2}${/TEX}O, and 0.3% malt ext. at 3$0^{\circ}C$. The oilgosaccharide produced by enzyme reaction from inulin was identified as DFA III by and {TEX}${13}^C${/TEX}-NMR spectrosocpy.

• Korean Journal of Metals and Materials
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• v.48 no.9
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• pp.791-797
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• 2010

The creep crack growth rate (da/dt) of the Cr-Mo steels tested by pre-crack and the voltage (or resistance) variables were related into fracture parameter (Ct), crack growth coefficient (H), and an exponent (q) in the parts of Base, weld and HAZ. The fracture parameter (Ct) has various variables relating to the specimen and crack shape, applied stress, and creep strain curve. The H and q was inferred by OLS regression (ordinary least square method), and the H values were solved in statistics and probability assessment, which were attained fromPDF's distributions (probability density function). The HAZ part has the highest value of q by OLS regression and the widest distribution of H by PDF of WEIBULL, which means that the crack sensitivity of HAZ should be cautioned against the creep crack growth and failure.

• Steel and Composite Structures
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• v.38 no.6
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• pp.691-703
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• 2021

In this study, experiments were conducted to evaluate the flexural performance of prestressed hybrid wide flange (PHWF) beams with hollowed steel webs. A total of four PHWF beams were fabricated, where the width and spacing of the steel webs and the presence of cast-in-place (CIP) concrete were set as the main test parameters, and their flexural behavior and crack patterns, and the longitudinal strain distribution in a section with respect to the width and spacing of the steel webs were analyzed in detail. The experiment results showed that, as the ratio of the width to the spacing of the steel webs decreased, the flexural stiffness and strength of the PHWF beams without CIP concrete decreased. In addition, in the case of composite PHWF beam with CIP concrete, fully composite behavior between the precast concrete and the CIP concrete was achieved through the embedded steel member. Finite element analyses were performed for the PHWF beams considering the bond properties between the hollowed steel webs and concrete, and nonlinear flexural analyses were also conducted reflecting the pre-compressive strains introduced only into the bottom flange. From the comparison of the test and analysis results, it was confirmed that the analysis models proposed in this study well evaluated the flexural behavior of PHWF beams with and without CIP concrete.

• Progress in Superconductivity and Cryogenics
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• v.11 no.3
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• pp.26-30
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• 2009

Korea Superconducting Tokamak Advanced Research(KSTAR) device is composed of 30 superconducting magnets, magnet structure, vacuum vessel, cryostat, current feeder system, and etc. KSTAR device is operated in the cryogenic temperature and high magnetic field. We install about 800 sensors - temperature sensors, stain gages, displacement gages, hall sensors - to monitor the thermal, mechanical, electrical status of KSTAR during operation. As a tremendous numbers of sensors should be installed for monitoring the KSTAR device, the method of effective installation was developed. The sensor test was successfully carried out to check its reliability and its reproduction in the cryogenic temperature. The sensor signal is processed by PXI-based DAQ system and communicated with central control system via machine network and is shown by Operator Interface(OPI) display in the main control room. In order to safely operate the device, any violations of mechanical & superconductive characteristic of the device components were informed to its operation system & operator. If the monitored values exceed the pre-set values, the protective action should be taken against the possible damage. In this paper, the system composition, operation criteria, operation result were presented.