• Earthquakes and Structures
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• v.20 no.3
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• pp.295-307
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• 2021

The gap provided between adjacent structures in the metropolitan cities is mostly narrow due to architectural and financial issues. Consequently, structural pounding occurs between adjacent structures during earthquakes. It causes damages, ranging from minor local to more severe ones, especially in the case of seismically isolated buildings, due to their higher displacements. However, due to the increased flexibility of isolated buildings, the problem could become more detrimental to such structures. The effect of the seismic pounding of moat walls on the response of buildings isolated by Triple Friction Pendulum Bearing (TFPB) is investigated in this paper. To this propose, two symmetric three-dimensional models, including single-story and five-story buildings, are modeled in Opensees. Nonlinear Time History Analyses (NTHA) are performed for seismic evaluation. Also, five different sizes with four different sets of friction coefficients are considered for base isolators to cover a whole range of base isolation systems with various geometry configurations and fundamental period. The results are investigated in terms of base shear, buildings' drift, and roof acceleration. Results indicated a profound effect of poundings against moat walls. In situations of potential pounding, in some cases, the influence of impact on seismic responses of multistory buildings was more remarkable.

• Korean Journal of Pharmacognosy
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• v.29 no.1
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• pp.1-7
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• 1998

Aqueous extract of Morus alba L. blocked the toxic effect of paraquat on E. coli growth. The active components in the extract may be capable of crossing the cell membranes and protect against superoxide toxicity in E. coli, The extract inhibited $FeSO_4/H_2O_2$ induced lipid peroxidation in rat liver homogenate and protected against t-butyl hydroperoxide caused Ac2F cell damage. Moreover, the extract showed inhibitory effect on phospholipase $A_2$ activity in a dose dependent manner. Antiinflammatory effect of the extract was further investigated using the carrageenin-induced oedema model. A single adminstration of the extract (3g/kg body, p.o.) was more effective than indomethacin. These results suggest that the isolation and identification of the active components would have significant therapeutic application to inflammation associated with oxygen radicals.

• Earthquakes and Structures
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• v.19 no.6
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• pp.427-444
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• 2020

The performance of an isolated horizontally curved continuous bridge with High Damping Rubber (HDR) Bearings has been investigated under seismic loading conditions. The effectiveness of response controls of the bridge by HDR bearings for various aspects viz. variation in ground motion characteristics, multi-directional effect, level of earthquake shaking, varying incidence angle, have been determined. Three recorded ground motions, representative of historical earthquakes along with near-field, far-field and forward directivity effects, have been considered in the study. The efficacy of the bearings with bidirectional effect considering interaction behavior of bearing and pier has also been investigated. Modeling and analysis of the bridge have been done by finite element approach. Sensitivity studies of the bridge response with respect to design parameters of the bearings for the considered ground motions have been performed. The importance of the nonlinearity of HDR bearings along with crucial design parameters has been identified. It has been observed that the HDR bearings performed well in different variations of ground motions, especially for controlling torsional moment. However, the deck displacement has been found to be increased significantly in case of Turkey ground motions, considering forward directivity effect, which needs to be paid more attention from designer point of view.

• Korean Journal of Materials Research
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• v.1 no.3
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• pp.132-138
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• 1991

A comparision was made on the influence of BPSG flow temperatures on the electrical properties in submicron CMOS DRAMs containing two BPSG layers. Three different combinations of BPSG flow temperature such as $850^{\circ}C/850^{\circ}C,\;850^{\circ}C/900^{\circ}C,\;and\;900^{\circ}C/900^{\circ}C$ were employed and analyzed in terms of threshold, breakdown and isolation voltage along with sheet resistance and contact resistance. In case of $900^{\circ}C/900^{\circ}C$ flow, the threshold voltage of NMOS was decreased rapidly in channel length less than $0.8\mu\textrm{m}$ with no noticeable change in PMOS and a drastic decrease in breakdown voltages of NMOS and PMOS was observed in channel length less than and equal to $0.7\mu\textrm{m}$ and $0.8\mu\textrm{m}$, respectively. Little changes in threshold and breakdown voltages of NMOS and PMOS, however, were shown down to channel length of $0.6\mu\textrm{m}$ in case of $850^{\circ}C/850^{\circ}C$ flow. The isolation voltage was increased with decreasing BPSG flow temperature. A significant increase in the sheet resistance and contact resistance was noticeable with decreasing BPSG flow temperature from $900^{\circ}C$ to $850^{\circ}C$. All these observations were rationalized in terms of dopant diffusion and activation upon BPSG flow temperature. Some suggestions for improving contact resistance were made.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.35 no.5
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• pp.1025-1037
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• 2015

Flexible base isolation bearings that separate superstructure from ground have been widely used in the construction field because they make a significant contribution to increasing the fundamental period of the structure, thereby decreasing response acceleration transmitted into the superstructure. However, the established bearing devices installed to uphold the whole building give rise to some problems involved with failure and collapse due to lack of the capacity as modern structures are getting more massive and higher. Therefore, this study suggests new isolation bearings assembled with additional restrainers enabled to reinforcing and recentering, and then evaluates their performance to withstand the seismic load. The superelastic shape memory alloy (SMA) bars are installed into the conventional lead-rubber bearing (LRB) devices in order to provide recentering forces. These new systems are modeled as component spring models for the purpose of conducting nonlinear dynamic analyses with near fault ground motion data. The LRB devices with steel bars are also designed and analyzed to compare their responses with those of new systems. After numerical analyses, ultimate strength, maximum displacement, permanent deformation, and recentering ratio are compared to each model with an aim to investigate which base isolation models are superior. It can be shown that LRB models with superelastic SMA bars are superior to other models compared to each other in terms of seismic resistance and recentering effect.

• Journal of the Korea institute for structural maintenance and inspection
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• v.25 no.6
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• pp.19-26
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• 2021

The seismic isolation system have been applied in order to protect the collapse of bridge by seismic load and the vertical load transmitted from the superstructure. However, the failure and damages of non-shrinkage mortar, isolator and wedge in total 12 bridge were reported by Pohang Earthquake. In this study, the damage mechanism and behavior characteristics of elastomeric bearing by an earthquake were evaluated to consider the seismic isolation system including non-shrinkage mortar and the seat concrete of pier. To discuss the effect of installed wedge and damage mode of elastomeric bearing, the compressive-shear tests were carried out. Also, the mechanical behaviors and damage mechanism for each component of elastomeric bearing were evaluated by using finite element analysis. From the test results, the cracks were created at boundary between non-shrinkage mortar and seismic isolator and the shear loads were rapidly increased after bump into wedge. The cause for damage mechanism of seismic isolation system was investigated by comparing stress distribution of anchor socket and non-shrinkage mortar depending on wedge during earthquake.

• Journal of the Society of Disaster Information
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• v.14 no.4
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• pp.466-473
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• 2018

Purpose: Nowadays, it is the trend that seismic isolation method and combined method are used for seismic retrofitting, if concrete sphere foundation(CSF) system is applied to mid and low rise RC structure for the seismic isolation, the characteristics of concrete sphere, etc split tensile strength will be need. Method: The various experiments are carried out to know the split strength of high strength concrete sphere(60Mpa) and the ratio of split strength of concrete sphere to standard cylinder specimen, the size effect of concrete sphere with diameter. Results: It was purposed that the split strength of concrete sphere with diameter 150mm will be lower than that of cylinder specimen but, the average value is 4.39 Mpa and the ratio is higher than that of cylinder specimens, each 3.8% and 13.7%, the reason of this result is thought that the internal stress action of spot load and line load are different. Conclusion: There is a standard method for split tensile strength of cylinder type specimen, but there are few studies for the tensile split of concrete sphere. And therefore, in this study, theoretical and experimental details of concrete sphere will be served for the concrete sphere foundation or other sequent studies.

• Journal of Korea Port Economic Association
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• v.30 no.3
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• pp.59-87
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• 2014

The purpose of this study is to examine the effect of two kinds of Master and Chief Engineer's communication style on group conflicts and members' attitude including job satisfaction and organizational commitment, and to analyze the moderating effect of the isolation from home and community on the relation between the both of communication styles and the several behavioral variables in ship organization. This empirical result demonstrates the fact that Master and Chief Engineer's direct communication with crew has lower conflict and higher job satisfaction and organizational commitment than their indirect one through Chief Officer and First Engineer. In addition, it illustrates the isolation from home only effects moderately on the relation between the communication style and group conflict, and also the direct communication style reduces more the conflict in the group to show less isolation from home. To conclude, this study reveals that job satisfaction and organization commitment could be heightened by proper communication style of Master and Chief Engineer and it would utilize the job performance of ship organization in the long-term.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2000.10a
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• pp.167-175
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• 2000

Seismic analyses of structures can`t be performed without considering the effect of soil-structure interaction and seismic responses of a structure taking into account the stiffnesses of a foundation-soil system show a significant difference from those with a rigid base. However, current seismic analyses of apartment building structures were carried out assuming a rigid base and ignoring the characteristics of a foundation and the properties of the underlying soil. In this study, seismic analyses of apartment buildings of a particular wall-slab structural type were carried out comparing seismic response spectra of a flexible base with those of a rigid base and UBC-97. Wall-slab type low-rise or mid-height apartment buildings built on the deep soil layer showed a rigid body motion with the reduced seismic responses due to the base isolation effect, indicating that it is too safe but uneconomical to utilize the design spectra of UBC-97 for the seismic analysis of a wall-slab type apartment buildings due to the too conservative design.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2009.10a
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• pp.267-271
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• 2009

This paper presents the improvement and application effect in fault restoration program based on distribution automation system(DAS) of KEPCO. When a fault occurs, fault restoration program can detect fault section based on FI information of DAS, and calculate the best restoration solution by comparing the load capacity of outage area and the spare load capacity of connected distribution lines, and propose switch operating procedure for fault section isolation and outage restoration. Fault restoration program was applied to real field and it was verified that this program is applicable to diverse field cases. By using this fault restoration program to the field human error can be reduced and fault procedure can be more reliable, accurate, and fast.