• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.4
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• pp.532-542
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• 2018

Because maglev trains have a propulsion and absorption force without contact with the rails, they can drive safely at high-speed with little oscillation. Recently, test model of a maglev propulsion train was produced and operated, and has since been chosen as a national growth industry in South Korea; there have been many studies and considerable investment in these fields. This study examined the dynamic responses due to bridge-maglev train interaction and basic material to design bridges for maglev trains travelling at high-speed. Depending on the major factors affecting the dynamic effects, the scope of this study was restricted to the relationship between dynamic responses. A concrete box girder was chosen as a bridge model and injured train and rail types in domestic production were selected as the moving train load and guideway analysis model, respectively. From the analysis results, the natural frequency of a bridge for a maglev train, which has a deflection limit L/2000, was higher than those of bridges for general trains. The dynamic responses of the girder of the bridge for a maglev train showed a substantial increase in proportion to the velocities of the moving train like other general bridge cases. Maximum dynamic response of the girder is shown at a moving velocity of 240km/h and increased with increasing moving velocity of train. These results can be used to design a bridge for maglev propulsion trains and provide the basic data to confirm the validity and verification of the design code.

• Journal of the Earthquake Engineering Society of Korea
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• v.12 no.4
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• pp.19-33
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• 2008

Dynamic response measurements from natural excitation were carried out for 25- and 42-story buildings to evaluate their inherent properties, such as natural frequencies, mode shapes and damping ratios. Both are reinforced concrete buildings adopting a core wall, or with shear walls as the major lateral force resisting system, but frames are added in the plan or elevation. In particular, shear walls in a 25-story building are converted to frames from the 4th floor level downwards while maintaining a core wall throughout, resulting in a fairly complex structure. Due to this, along with similar stiffness characteristics in the principal directions, significantly coupled and closely spaced modes of motion are expected in this building, making identification rather difficult. By using various state-of-the-art system identification methods, the modal parameters are extracted, and the results are then compared. Three frequency-domain and four time-domain based operational modal identification methods are considered. Overall, all natural frequencies and damping ratios estimated from the different identification methods showed a greater consistency for both buildings, while mode shapes exhibited some degree of discrepancy, varying from method to method. On the other hand, in comparison with analysis results obtained using the initial finite element(FE) models, test results exhibited a significant difference of about doubled frequencies, at least for the three lower modes in both buildings. To improve the correlation between test and analysis, a few manual schemes of FE model updating based on plausible reasons have been applied, and acceptable results are obtained. The advantages and disadvantages of each identification method used are addressed, and some difficulties that might arise from the updating of FE models, including automatic procedures, for such large structures are carefully discussed.

• Journal of Periodontal and Implant Science
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• v.37 no.4
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• pp.839-848
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• 2007

Purpose: Various kinds of biodegradable membranes are currently used in dental clinics. And the frequency and the necessity of their usage are increasing due to their numerous advantages. Therefore it is important to understand the difference of various membranes and histological reaction against implanted membranes. Materials and Methods: Biodegradable membranes of $Biogide^{(R)}$, $Resolute^{(R)}$, and $Tutodent^{(R)}$ were cut into small pieces by $1.0{\times}0.5cm$. The membranes were implanted 1.5cm apart from each other under the epithelium on the skull of 18 Sprague Dawley rats. The animals were sacrificed at 3, 7, and 14 days after surgical procedure. The specimens were examined by histological analysis. Results: 1. Early period after implantation of the membranes showed connective tissues surrounding membranes and there were a few inflammatory cells present. 2. In $Biogide^{(R)}$ and $Tutodent^{(R)}$ specimens, inflammatory cells and surrounding tissues were shown to infiltrate from outside with slight density difference inside. In $Resolute^{(R)}$ specimens, membranes were fragmented. Inflammatory cells and connective tissues were also observed inside. 3. In $Resolute^{(R)}$ specimen, giant cells were present which implicates that foreign body reaction has occurred. 4. $Biogide^{(R)}$ had lower integrity than other membranes and is not enough to be used alone in defect area. However, $Resolute^{(R)}$ had superior firmness than others. $Tutodent^{(R)}$ had middle level of integrity. Conclusion: This experimental model enabled to observe early inflammatory reactions and morphological changes of materials and can be used to develop and evaluate the efficacy of biodegradable membranes. Duplication of standardized human oral environment will be required in future experiments.

• Journal of the Earthquake Engineering Society of Korea
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• v.9 no.5 s.45
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• pp.41-52
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• 2005

Using the variable control gain scheme on the basis of fuzzy-based decision-making process, Fuzzy supervisory control (FSC) technique exhibits better control performance than linear control technique with one static control gain. This paper demonstrates the effectiveness of the FSC technique by evaluating the robust performance of the FSC technique under the presence of uncertainties in the models and the excitations. Robust performance of the FSC system is compared with that of optimally designed LQG control system for the benchmark cable-stayed bridge presented by Dyke et al. Parameter studies on the robust performance evaluation are carried out by varying the stiffness of the bridge model as well as the magnitudes of several earthquakes with different frequency contents. From the comparative study of two control systems, FSC system shows the enhanced control performance against various magnitudes of several earthquakes while maintaining lower level of power required for controlling the bridge response. Especially, FSC system clearly guarantees the improved robust performance of the control system with stable reduction effects on the seismic responses and slight increases in total power and stroke for the control system, while LQG control system exhibits poor robust performance.

• The Journal of the Acoustical Society of Korea
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• v.35 no.3
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• pp.175-182
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• 2016

For application to several MHz photoacoustic imaging systems, a needle hydrophone was designed and fabricated by using PMN-PZT piezoelectric single crystal, and its characteristics were evaluated through comparison with a commercial PVDF(Polybinylidene Fluoride) hydrophone of which receiving sensitivity is known. The simulation using the KLM model results show that the peak receiving impulse response for $50{\Omega}$ terminating impedance of the fabricated hydrophone is -261.6 dB re $1V/{\mu}Pa$ and the frequency response is relatively flat over 2 ~ 12 MHz with fluctuation less than 5 dB. The measurement results using tone burst signals also show that it has higher (ave. 10.9 dB) sensitivity than the commercial hydrophone in 2 ~ 8 MHz, and the receiving sensitivity of $-255.8{\pm}2.8$ dB re $1V/{\mu}Pa$ was measured for the fabricated hydrophone. In addition, it is known that the photoacoustic signals and the image of a hair obtained by a mechanical scanned photoacoustic imaging system with the fabricated hydrophone were bigger and better than those obtained with the commercial hydrophone.

• Asian-Australasian Journal of Animal Sciences
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• v.16 no.8
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• pp.1193-1198
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• 2003

An increase in frequency of administration of exogenous growth hormone (GH) or GH-releasing hormone was reported to be a model to increase blood circulating insulin-like growth factor-1 (IGF-1) and to improve growth performance in animals. We have investigated the effect of twice daily administration of GH-releasing peptide-2 (GHRP-2) on growth performance, GH responsiveness and plasma insulin-like growth factor IGF-1 in swine. We administered to eight swine, 3 control and 5 treatment, a twice daily s.c. injections of GHRP-2 ($30{\mu}g/kg\;BW$) for a period of 10 days. Every day blood samples immediately taken before injections of GHRP-2 or saline, at 08:00 h and 16:00 h, were measured for IGF-1 concentrations. Blood samples for GH assay were collected every 20 min on days 1, 6 and 10, from 1 hour before and 3 h after GHRP-2 or saline injections at 08:00 h. GH peak concentrations and GH area under curve (GH AUC) on day 1, 6 and 10 in treatment group of swine were higher than those in control swine (p<0.05). Twice daily administration of GHRP-2 caused a significantly attenuation (p<0.05) of GH peak concentrations ($80.25{\pm}13.87$, $39.73{\pm}5.72$ and $27.57{\pm}6.06ng/ml$ for day 1, 6 and 10, respectively) and GH AUCs ($3,536.15{\pm}738.35$, $1,310.31{\pm}203.55$ and $934.37{\pm}208.99ng/ml$ for day 1, 6 and 10, respectively). However, there was no significant difference in GH peak concentration and GH AUC between day 6 and 10. Plasma IGF-1 concentration levels were higher in treatment than control group of swine (p<0.05) after 3 days of the treatment, and the levels reached a plateau from day 3 to 10 of experiment. Growth performance did not alter by GHRP-2 administration, even though a numerical increase of body weight gain and feed efficiency was observed. These results indicate that twice daily administration of GHRP-2 for 10 days in swine did not significantly influence on growth performance, caused an overall attenuation of GH response, and that elevation of plasma GH concentrations caused by GHRP-2 administration increased plasma IGF-1 concentrations, even though an attenuation of GH response was observed.

• Geophysics and Geophysical Exploration
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• v.4 no.2
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• pp.25-33
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• 2001

Loop-loop electromagnetic (EM) survey in frequency domain has been carried out in order to provide basic solution to geotechnical applications. Source and receiver configuration may be horizontal co-planar (HCP) and/or vertical co-planar (VCP). Three quadrature components of mutual impedance ratio for each configuration are used to construct the subsurface image. For the purpose of obtaining the model response and validating the reasonable performance of the inversion, we obtained each responses of two-layered and three-layered earth models and two-dimensional (2-D) isolated anomalous body. The response of 2-D isolated anomalous body has been calculated using extended Born approximation for the solution of 2.5-D integral equation describing EM scattering problem. As a result of the least-squares inversion with variable Lagrangian multiplier, we could construct more resolvable image from HCP data than VCP data. Furthermore, joint inversion of HCP and VCP data made better stability and resolution of the inversion. Resistivity values, however, did not exactly match the true ones. Loop-loop EM field data was obtained with EM34-3XL system manufactured by Geonics Ltd. (Canada). Electrical resistivity survey was conducted on the same line for the comparison in advance. Since the constructed image from loop-loop EM data by 2-D inversion algorithm showed almost similar resistivity distribution to that from electrical resistivity one, we expect the developed 2.5-D loop-loop EM inversion program can be applied for the reconnaissance site survey.

• Korean Journal of Acupuncture
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• v.38 no.3
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• pp.151-161
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• 2021

Objectives : The effects of a combined stimulation of 658 nm, 830 nm, 904 nm, and 1064 nm laser acupuncture treatment (LAT) and electroacupuncture treatment (EAT) on GB39 and GB34 on neuropathic pain in rats induced by tibial and sural nerve transection were studied in this paper. Methods : To express a neuropathic pain model, surgery was performed to transection rats' tibial and sural nerves. The rats were divided into normal group, control group, and experimental groups. In addition, the experimental groups were divided into 658 nm laser and electroacupuncture (LAT658+EAT), 830 nm laser and electroacupuncture (LAT830+EAT), 904 nm laser and electroacupuncture (LAT904+EAT), and 1064 nm laser and electroacupuncture (LAT830+EAT). For the treatment of the experimental groups, electroacupuncture and different laser wavelengths were alternately applied to GB34 and GB39 twice a week for 3 weeks for 1 minute 30 seconds. The withdrawal response of neuropathic rats' legs by acetone stimulation was observed, as well as the c-Fos in the central gray region in the midbrain of neuropathic rats together with Bax, Bcl2, and mGluR5 expressions associated with apoptosis. Results : Compared with the control group, a significant decrease in the frequency of paw withdrawal in response to acetone allodynia was observed in LAT658+EAT and LAT830+EAT groups in 6th times, LAT904+EAT group in 2^nd, 3^rd, and 6^th times, and LAT1064+EAT group in 2^nd and 6^th times, respectively. For c-fos positive cells in the central gray region, a significant decrease was observed in LAT830+EAT, LAT904+EAT, and LAT1064+EAT groups in comparison with the control group. In Bax expression, LAT1064+EAT group showed a significant decrease compared to the control group. In Bcl-2 expression, the LAT658+EAT,the LAT904+EAT, and the LAT1064+EAT groups increased significantly compared to the control group. LAT830+EAT, LAT904+EAT, and LAT1064+EAT groups showed significantly increased mGlu5 expression compared to the control group. Conclusions : The combination of laser for each wavelength and electroacupuncture alternately performed in this study is thought to be effective in improving neuropathic pain and apoptosis.

• Journal of the Korean Regional Science Association
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• v.34 no.4
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• pp.35-48
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• 2018

The purpose of this study is to empirically investigate the experiences and subjective opinions of urban agriculture in order to explore ways to vitalize urban agriculture. More specifically, we divides environmental value into three categories of ecology, landscape, and participation, and defines a function of urban agriculture to improve environmental values related to the three categories mentioned above. The main results of the empirical analysis using the survey data are summarized as follows. First, the probability of gathering information about urban agriculture is higher in metropolitan cities than small cities, and the larger the residence size, the higher the probability of actual urban agriculture participation. Second, the positive response rate was high for the three categories of urban agriculture, while the negative response rate was high for the surrounding environment. The implications derived from the analysis are as follows. First, the opposite results of experiences of urban agriculture suggests that local governments should further promote urban agriculture-based investment policies. In addition, these policies need to be preceded by analysis of the characteristics of population groups in the region Also, it is necessary to improve the environment through urban agriculture.

• Journal of the Korean Association of Geographic Information Studies
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• v.21 no.4
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• pp.191-201
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• 2018

Recently, the frequency of heavy rainfall is increasing due to the effects of climate change, and heavy rainfall in urban areas has an unexpected and local characteristic. Floods caused by localized heavy rains in urban areas occur rapidly and frequently, so that life and property damage is also increasing. It is crucial how fast and precise observations can be made on successful flood management in urban areas. Local heavy rainfall is predominant in low-level storms, and the present large-scale radars are vulnerable to low-level rainfall detection and observations. Therefore, it is necessary to introduce a new urban flood forecasting system to minimize urban flood damage by upgrading the urban flood response system and improving observation and forecasting accuracy by quickly observing and predicting the local storm in urban areas. Currently, the WHAP (Water Hazard Information Platform) Project is promoting the goal of securing new concept water disaster response technology by linking high resolution hydrological information with rainfall prediction and urban flood model. In the WHAP Project, local rainfall detection and prediction, urban flood prediction and operation technology are being developed based on high-resolution small radar for observing the local rainfall. This study is expected to provide more accurate and detailed urban flood warning system by enabling high-resolution observation of urban areas.