• Journal of the Korean Society for Nondestructive Testing
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• v.27 no.4
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• pp.345-353
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• 2007

We have obtained a topographical image nondestructively for a Cu thin film in liquid using a near-field scanning microwave microscope (NSMM), its operating frequency was 3.5 to 5.5 GHz. We have kept a distance of 10 nm between tip and sample using a quartz tuning fork shear force feedback system. As an end of tip was attached to one prong of the quartz tuning fork has a length of 2 mm, the only tip of tuning fork was immersed in water tank. A loss cause by evaporation in water tank is regulated with actuator was connected to a supplementary tank. Moreover, using a revise program of LabView, we could increase the accuracy of a measurement in liquid.

• Korean Journal of Food Science and Technology
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• v.34 no.4
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• pp.637-641
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• 2002

The purpose of this study was to provide the basic information on the cookies made with garlic and to investigate quality characteristics of them using chemical and sensory evaluation of cookies. Cookie samples were prepared with shredded garlic at varied levels of 0, 3, 6 and 9%. The pH of the dough significantly decreased by the addition of garlic. Dough density of control showed significantly lower values than those of 3% added sample groups. Spreadability of control had significantly higher values than the other samples. Texture measurement showed that the addition of garlic had no significant effect on cookie texture. Sensory evaluation resulted that the properties of crack, garlic aroma, garlic taste and brittleness of cookies tended to increase as the addition levels of garlic were increased. The cookies with 3% and 6% garlic had similar or significantly higher acceptance scores in all of the properties examined than those of control.

• Korean Journal of Food Science and Technology
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• v.51 no.1
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• pp.18-23
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• 2019

An enzymatically saccharified tapioca and hulled barley (TB) raw mixed solution was used to examine alcohol fermentation characteristics. The TB mixture was liquefied with 0.04% ${\alpha}-amylase$ "Spezyme-Fred" and saccharified using an enzyme mixture (GPB), which consisted of glucoamylase (G), protease (P), and ${\beta}-glucanase$ (B). After the TB mixture (7:3, w/w) saccharified for 150 min at $50^{\circ}C$, its glucose content was 12.9% and viscosity was 26 cp. The use of GPB for the saccharification of TB was appropriate because the addition of ${\beta}-glucanase$ increases the glucose yield and decreases the viscosity of the saccharification liquid. The TB ratio was optimized to 7:3 (w/w) on the basis of the lower viscosity and the higher glucose content after saccharification. After TB mixture with 300% (w/w) water content was better condition than others for alcohol fermentation when it was carried out at $30^{\circ}C$. The alcohol and glucose contents of the TB mixture fermented for 72 h were 9.0 and 0.02%, respectively, and the pH and total acidity were 4.3 and 0.3%, respectively.

• Journal of the Korean Geosynthetics Society
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• v.20 no.1
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• pp.45-55
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• 2021

In this study, the behavioral characteristics of the fill dam were analyzed during water level fluctuations through a numerical analysis model, and the reservoir safety management plan was prepared. The variation in plastic deviatoric strain, horizontal displacement, stress path, pore water pressure, etc., due to elevation of water level in the upper and lower sides of shell and core were analyzed using numerical analysis software, viz. GTS NX and LIQCA. The analysis results manifest that as the water level in the dam body increases rapidly, the pore water pressure and displacement also increase quickly. It was found that the elevation of the water level causes an increase in pore water pressure in the dam body as well as an increase in the saturation of the dam body and decreased effective stress. It is considered that this type of dam behavior can be the cause of the reduction of strength and stiffness of the dam. Also, it is assumed that the accumulated plastic deviatoric strain due to the deformation of the dam body caused by water infiltration causes an increase in displacement. Based on these experimental results and the results of analyses of the existing reservoir safety diagnosis techniques, an improvement plan for dam safety diagnosis and evaluation criteria was proposed, and these results can be used as primary data while revising dam safety diagnosis guidelines.

• Journal of the Korean Geotechnical Society
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• v.37 no.11
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• pp.51-60
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• 2021

River scour erodes the soil around the pier, reducing the lateral bearing capacity of the pier and lowering the stability of the structure. In this study, in order to examine the effect of scouring on the stability of the structure, an experiment was performed to measure the natural frequency of the pier according to the excavation of the surrounding ground. Impact vibration test was conducted on the pier with the caisson foundation of the Mangyeonggang Bridge, which is scheduled to be demolished. Accelerometers were attached to the top, center, and bottom of the pier and the acceleration responses were measured by hitting those three points. The experimental results showed that the top hit showed consistent and reasonable results of the acceleration responses according to the hitting position. The measured accelerations were converted to the frequency domain through Fast Fourier Transform (FFT), and then the natural frequency was determined. In addition, to analyze the scour effect on the natural frequency of the pier, the ground around the pier was excavated and the natural frequency change was analyzed. As a result, the natural frequency showed the decreasing tendency according to the excavation depth, but the decrease was small due to the large stiffness of the caisson foundation.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.35 no.5
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• pp.277-286
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• 2022

The elastic and inelastic responses obtained from the experimental and analytical results of two RC building structures under the service level earthquake (SLE) and maximum considered earthquake (MCE) in Korea were used to weinvestigate the characteristics of the mechanisms resisting shear and torsional behavior in torsionally unbalanced structures. Equations representing the interactive effect of translational drift and torsional deformation on the shear force and torsional moment were proposed. Because there is no correlation in the behavior between elastic and inelastic forces and strains, the incremental shear forces and incremental torsional moments were analyzed in terms of their corresponding incremental drifts and incremental torsional deformations with respect to the yield, unloading, and reloading phases around the maximum edge-frame drift. In the elastic combination of the two dominant modes, the translational drift mainly contributes to the shear force, whereas the torsional deformation contributes significantly to the overall torsional moment. However, this phenomenon is mostly altered in the inelastic response such that the incremental translational drift contributes to both the incremental shear forces and incremental torsional moments. In addition, the given equation is used to account for all phenomena, such as the reduction in torsional eccentricity, degradation of torsional stiffness, and apparent energy generation in an inelastic response.

• Journal of the Korean Society of Radiology
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• v.16 no.7
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• pp.995-1006
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• 2022

The purpose of this study was to investigate the current status of practical course operation in a non-face-to-face online environment, learning effects, and students' experiences and perceptions for radiology major students using a survey. The questionnaire consisted of a total of 34 items in 5 areas: general characteristics of subjects, current learning participation in non-face-to-face environments, learning satisfaction, learning outcomes, improvement and requirements. For the analysis of the questionnaire responses, frequency analysis was performed on the response frequency, ratio, and scale for each item. Based on the general characteristics of the survey respondents, cross-analysis was performed using the chi-square test for participation in non-face-to-face learning, learning performance, and learning satisfaction. implemented. Improvements and requirements were qualitatively analyzed for the repetition frequency of words with the same meaning. Through the results of analyzing the responses of a total of 397 questionnaires, the direction of design and development of practical classes in a non-face-to-face environment in the future and basic information and implications for efficient operation were confirmed. Based on this, it is necessary to continue to think and make efforts for the efficient operation of non-face-to-face practice classes in the post-corona era.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.1A
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• pp.61-73
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• 2009

In this paper, hybrid health monitoring techniques using acceleration-impedance features are newly proposed to detect two damage-type in steel plate-girder bridges, which are girder's stiffness-loss and support perturbation. The hybrid techniques mainly consists of three sequential phases: 1) to alarm the occurrence of damage in global manner, 2) to classify the alarmed damage into subsystems of the structure, and 3) to estimate the classified damage in detail using methods suitable for the subsystems. In the first phase, the global occurrence of damage is alarmed by monitoring changes in acceleration features. In the second phase, the alarmed damage is classified into subsystems by recognizing patterns of impedance features. In the final phase, the location and the extent of damage are estimated by using modal strain energy-based damage index method and root mean square deviation (RMSD) method. The feasibility of the proposed hybrid technique is evaluated on a laboratory-scaled steel plate-girder bridge model for which hybrid acceleration-impedance signatures were measured for several damage scenarios. Also, the effect of temperature on the accuracy of the impedance-based damage monitoring results are experimentally examined from combined scenarios of support damage cases and temperature changes.

• Journal of the Korea institute for structural maintenance and inspection
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• v.27 no.6
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• pp.86-93
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• 2023

As the hysteretic behavior of reinforced concrete members under cyclic loading progresses, the energy dissipation ability decreases due to a decrease in stiffness and strength and pinching effects. However, the guideline "Nonlinear Analysis Model for Performance-Based Seismic Design of Reinforced Concrete Building Structures, 2021" requires calculating a single energy dissipation factor for each member and all histeric step, so the decrease in energy dissipation capacity according to histeric step cannot be considered. It is judged that Therefore, in this study, the energy dissipation factor according to the histeric step was examined by comparing the existing experimental results and the nonlinear time history analysis results for a general beam under cyclic loading. The energy dissipation factor was calculated as the ratio of the energy dissipation amount of the actual specimen to the energy dissipation amount of the idealized elastoplastic behavior obtained as a result of nonlinear time history analysis. In the existing experiment results, the energy dissipation factor was derived by calculating one cycle for each histeric step, and the energy dissipation factor was derived based on the nonlinear modeling process in the guidelines. In the existing experimental study, the energy dissipation factor was calculated by setting each histeric step (Y-L-R), and the energy dissipation factor was found to be 0.36 in the Y-L step and 0.28 in the L-R step, and the energy dissipation factor in the guideline was found to be 0.31. This shows that the energy dissipation factor calculation formula in the guidelines does not indicate a decrease in the energy dissipation capacity of reinforced concrete members.

• Proceedings of the KSR Conference
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• 2007.11a
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• pp.480-493
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• 2007

Many railway-advanced countries are using the various types of track to reduce the track maintenance and repair cost according to the improvement of velocity. It spends on much maintenance and repair cost for ballast track due to abrasion of ballast, track irregularity and unisotropical ballast-support stiffness. The ballast track on railway bridge is accelerating the deterioration of ballast according to interaction of railway bridge and track. As continuing the deterioration, it is caused dynamic loads. Due to these effects, it increases negative loads of track and bridge. However, when designing the railway bridge, the effect of ballast track was applicate only dead load, so elastic behavior effect of ballast track is not influenced. Therefore, this paper presumes the stiffness of ballast track on railway bridge considering dynamic behavior of railway bridge, it was evaluated that effect on dynamic behaviors of railway bridge according to ballast track stiffness.