• Journal of the Korean Geotechnical Society
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• v.34 no.1
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• pp.25-35
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• 2018

Geocentrifuge tests are performed to investigate the structure-soil-structure interaction of shallow foundations that have various sizes. The soil specimen is prepared by using the air-pluviation, and the dynamic responses of the foundation are monitored with separation distances between the two foundations and the embedment. During the centrifugal test, the measured ground acceleration shows a tendency to increase with the increase of the input seismic amplitude, and maximum acceleration is measured at the surface due to the ground amplification. As the separation distance between the two foundations decreases, the ratio of the response spectral acceleration (RRS) increases and the period at the peak RRS decreases due to the structure-soil-structure interaction (SSSI). The RRS of the two foundations tends to decrease when the foundations are buried in the ground at the same separation distance.

• International Journal of High-Rise Buildings
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• v.5 no.1
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• pp.51-62
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• 2016

The concept of introducing viscous damping devices between outriggers and perimeter columns in tall buildings to provide supplementary damping and improve performance, reduce structural costs, and increase available usable area was developed and implemented by Smith and Willford (2007). It was recognized that the relative vertical movement that would occur between the ends of outriggers and columns, if they were not connected, could be used to generate damping. The movements, and correspondingly damping, can potentially be significantly increased by amplifying them using simple "mechanisms". The mechanisms also make it possible to increase the number of available dampers and thus further increase supplementary damping. The feasibility of mechanisms to amplify supplementary damping and enhance structural performance of tall, slender buildings is studied with particular focus on its efficacy in improving structural performance in wind loads.

• 한국경영정보학회:학술대회논문집
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• 2008.06a
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• pp.1023-1028
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• 2008

Recently the advent of web 2.0 era is an important trend in the business environmental change. Web 2.0 era means users' active participation, share, and openness, develop 'Internet penetration into everyday life,' and change many aspects of our society. web 2.0 has been making these following changes in the socioeconomic aspects: 1) acceleration of system shift to a small quantity of multi-species production system 2) growing influence of on-line channel/information to consumers 3) various minorities' power increase in the socioeconomic sector. Web 2.0 has been making these following changes in the firms' strategies for information management: 1) increase of external knowledge and information utilization 2) amplification and reproduction of information from customers 3) change of information distribution: pursuit of two-way communication with customers 4) integration of different information/services for business transformation. Firms must squarely look at socioeconomic changes owing to web 2.0, and utilize them for firms' effective information management.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.1427-1428
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• 2015

MEMS(Micro Electro-mechanical System) are getting attention as promising industry in the 21st century. Car air bags, acceleration sensors, and medical, information appliances are being actively applied in MEMS. This paper suggest the electrical electrodes of brain signal applied MEMS model and the prototype design for EEG signal amplification circuit. Also, we suggest an independent BCI(Brain Computer Interface) system with brain electrical signal of electrode models and wireless communication platform.

• Journal of the Korean Society of Safety
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• v.24 no.6
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• pp.86-92
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• 2009

In the safety check of gravity dams at earthquake, there have been two types of analysis conducted simultaneously; one is stability analysis and the other stress analysis. But those are essentially the same calculation other than the former considers the dams rigid, while the latter considers the dams' dynamic characteristics which results in the amplification of response acceleration on the upper part of dam body. In this paper, the identity of those two methods is verified by example calculation in terms of stability check of gravity dam. It can be concluded that if stress analysis were performed, stability check of gravity dam could be accomplished with the results from stress analysis, removing unnecessary present dual calculation practice.

• Journal of the Korean GEO-environmental Society
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• v.20 no.5
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• pp.5-12
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• 2019

On November 15, 2017, a unpredictable liquefaction damage was occurred at the $M_L=5.4$ Pohang earthquake and after, many researches have been conducted in Korea. In Korea, where there were no cases of earthquake damage, it has been extremely neglectable in preparing earthquake risk maps and building earthquake systems that corresponded to prevention and preparation. Since it is almost impossible to observe signs and symptoms of drought, floods, and typhoons in advance, it is very effective to predict the impacts and magnitudes of seismic events. In this study, 14,040 borehole data were collected in the metropolitan area and liquefaction evaluation was performed using the amplification factor. Based on this data, liquefaction hazard maps were prepared for ground accelerations of 0.06 g, 0.14 g, 0.22 g, and 0.30 g, including 200years return period to 4,800years return period. Also, the correlation analysis between the earthquake acceleration and LPI was carried out to draw a real-time predictable liquefaction hazard map. As a result, 707 correlation equations in every cells in GIS map were proposed. Finally, the simulation for liquefaction risk mapping against artificial earthquake was performed in the metropolitan area using the proposed correlation equations.

• Journal of the Earthquake Engineering Society of Korea
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• v.16 no.3
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• pp.35-42
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• 2012

We propose a probabilistic method to evaluate the uniform hazard spectra (UHS) of the soil of nuclear power plant(NPP) sites corresponding to that of a bedrock site. To do this, amplification factors on the surface of soil sites were estimated through site response analysis while considering the uncertainty in the earthquake ground motion and soil deposit characteristics. The amplification factors were calculated by regression analysis with spectral acceleration because these two factors are mostly correlated. The proposed method was applied to the evaluation of UHS for the KNGR (Korean Next Generation Reactor) and the APR1400 (Advanced Power Reactor 1400) nuclear power plant sites of B1, B4, C1 and C3. The most dominant frequency range with respect to the annual frequency of earthquakes was evaluated from the UHS analysis. It can be expected that the proposed method will improve the results of integrated risk assessments of NPPs rationally. We expect also that the proposed method will be applied to the evaluation of the UHS and of many other kinds of soil sites.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2005.03a
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• pp.3-10
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• 2005

In this study, 1-g shaking table tests on the model of CFR(Concrete-Face Rockfill) type "D" dam in operation and the model of virtual ECRD(Earth Core Rockfill Dam) of which static stability is about the same compared to the model of CFRD were carried out. The purpose of this study is to compare the seismic performance of CFRD and ECRD from the analysis of model test results. Displacement response behavior of the dam was examined through the measurement of vertical and horizontal displacement of model dam crest. Also, amplification characteristics of accelerometers installed with dam height were examined through the measurement of acceleration with dam height. Also, in the case of ECRD, patterns of excess pore pressure generation with dam height were examined. From the test results, it was found that accelerations of dam crest of CFRD and ECRD were amplified about 1.52 times and 2 times compared to the accelerations of dam bottom, respectively. amplification was outstanding at three quarters of dam height from the bottom of dam. This phenomenon was outstanding in case of ECRD. And it was estimated that vertical and horizontal displacement of prototype dam of CFRD were 6.8cm (0.1% of dam height) and 12.3cm (0.2% of dam height), respectively. Also, it was estimated that vertical and horizontal displacement of prototype dam of ECRD were 4.3cm (0.1% of dam height) and 5.5cm (0.11% of dam height), respectively.

• Journal of the Earthquake Engineering Society of Korea
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• v.8 no.3
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• pp.23-32
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• 2004

The local geologic and dynamic site characteristics, which include soil profiles, shear wave velocity profiles and depths to the bed rock were gathered from 148 sites all over the Korean peninsula and those values are compared to those in the western USA. Site response analyses were performed based on equivalent linear scheme using design rock-outcrop acceleration of 0.154g which corresponds to the collapse level of earthquake for seismic category I structure. The results show that the amplification factor based on Korean seismic design guideline underestimates the motion in short-period range and overestimates the motion in mid-period range. It is suggested that the existing Korean seismic guideline based on UBC is required to be modified considering dynamic site characteristics in Korea for the reliable estimation of site amplification.

• Earthquakes and Structures
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• v.20 no.2
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• pp.187-200
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• 2021

The main factor for the amplification of ground motions near the crest or the toe of a slope is the reflection of the incident waves. The effects of the slope topography on the surrounding lands over the crest or at the toe can amplify the seismic responses of buildings. This study investigates the seismic performance of the slope topography and three mid-rise buildings (five, ten, and fifteen-storey) located near the crest and toe of the slope by 3D numerical analysis. The nonlinear model was used to represent the real behavior of building and ground elements. The average results of seven records were used in the investigations. Based on the analysis, the amplification factor of acceleration near the crest and toe of the slope was the most effective at distances of 2.5 and 1.3 times the slope height, respectively. Accordingly, the seismic performance of buildings was studied at a distance equal to the height of the slope from the crest and toe. The seismic response results of buildings showed that the slope topography to have little impact on up to five-storey buildings located near the crest. Taking into account a topography-soil-structure interaction system increases the storey displacement and base shear in the building. Accordingly, in topography-soil-structure interaction analyses, the maximum lateral displacement was increased by 71% and 29% in ten and fifteen-storey buildings, respectively, compare to the soil-structure interaction system. Further, the base shear force was increased by 109% and 78% in these buildings relative to soil-structure interaction analyses.