• Structural Engineering and Mechanics
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• v.60 no.4
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• pp.633-653
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• 2016

One of the major threats to the stability of classical columns and colonnades are earthquakes. The behavior of columns under high seismic excitation loads is non-linear and complex since rocking, wobbling and sliding failure modes can occur. Therefore, three dimensional simulation approaches are essential to investigate the in-plane and out-of-plane response of such structures during harmonic and seismic loading excitations. Using a software based on the Distinct Element Method (DEM) of analysis, a three dimensional numerical study has been performed to investigate the parameters affecting the seismic behaviour of colonnades' structural systems. A typical section of the two-storey colonnade of the Forum in Pompeii has been modelled and studied parametrically, in order to identify the main factors affecting the stability and to improve our understanding of the earthquake behaviour of such structures. The model is then used to compare the results between 2D and 3D simulations emphasizing the different response for the selected earthquake records. From the results analysis, it was found that the high-frequency motion requires large base acceleration amplitude to lead to the collapse of the colonnade in a shear-slip mode between the drums. However, low-frequency harmonic excitations are more prominent to cause structural collapse of the two-storey colonnade than the high-frequency ones with predominant rocking failure mode. Finally, the 2D analysis found to be unconservative since underestimates the displacement demands of the colonnade system when compared with the 3D analysis.

• Structural Engineering and Mechanics
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• v.64 no.2
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• pp.233-241
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• 2017

Earlier numerous studies have been done on implementation of Tuned Liquid Damper (TLD) for structural vibration control by many researchers. As per current review there is no significant study on a sloped bottom TLD. TLD's are passive devices. A TLD is a tank rigidly attached to the structure and filled partially by liquid. When fundamental linear sloshing frequency is tuned to structure's natural frequency large sloshing amplitude is expected. In this study set of experiments are conducted on flat bottom and sloped bottom TLD at beach slope $20^{\circ}$, $30^{\circ}$ and $45^{\circ}$, for different types of structures, mass ratio, and depth ratio to investigate the overall effectiveness of TLD and specific effect of TLD parameters on structural response. This experimental study shows that a properly designed TLD reduces structural response. It is also observed that effectiveness of TLD increases with increase in mass ratio. In this experimental study an effectiveness of sloped bottom TLD with beach slope $30^{\circ}$ is investigated and compared with that of flat bottom TLD in reducing the structural response. It is observed from this study that efficiency of sloped bottom TLD in reducing the response of structure is more as compared to that of flat bottom TLD. It is shown that there is good agreement between numerical simulation of flat bottom and sloped bottom TLD and its experimental results. Also an attempt has been made to investigate the effectiveness of sloped bottom TLD with beach slope $20^{\circ}$ and $45^{\circ}$.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.10
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• pp.1973-1980
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• 2017

In the case of a small UUV operating an active synthetic aperture sonar, various velocity disturbances may occur on the path due to the influence of external underwater environment, and this causes phase errors in coherent synthetic aperture processing, which has a large influence on the detected image. In this paper, when a periodic sinusoidal velocity disturbance is generated in the traveling direction, the phase generated by the round trip slope range at each position is estimated the cross correlation coefficient for multiple received signals and compensated the position variation in the overlapped DPC by the average value within the maximum allowable width. Through simulations, it has been confirmed that the images degraded by the velocity disturbance amplitude and fluctuating frequency of the UUV are removed from the false targets and the performance of azimuth resolution is improved by the proposed phase compensation method.

• The Korean Journal of Physiology
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• v.25 no.1
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• pp.17-26
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• 1991

Single smooth muscle cells of the rabbit pulmonary artery were isolated by treatment with collagenase and elastase. Using the patch clamp technique, potassium channel activity was recorded from the inside-out membrane patch. The channel had a sin히e channel conductance of about 360 pS in symmetrical concentration of K on both sides of the patch, 150 mM, and had a linear current-voltage relationship. During the application of 10 mM tetraethylammonium (TEA) to the intracellular membrane surface, the amplitude of single channel current was reduced and very rapid flickering appeared. The open probability $(P_0)$ of this channel was increased by increasing positivity of the potential across the patch membrane, with e-fold increase by 20 mV depolarization, and by increasing the internal $Ca^{2+}$ concentration. These findings are consistent with those of large conductance Ca-activated K channels reported in other tissues. But the shortening of the mean open time by increasing $[Ca^{2+}]_i$, was an unexpected result and one additional closed state which might be arisen from a block of the open channel by Ca binding was suggested. The $P_0-membrane$ potential relationship was modulated by internal pH. Decreasing pH reduced $P_0$. Increasing pH not only increased $P_0$ but also weakened the voltage dependency of the channel opening. The modulation of Ca-activated K channel by pH was thought to be related to the mechanism of regulation of vascular tone by the pH change.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.18 no.6
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• pp.497-505
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• 1985

We studied the annual and interannual fluctuations of sea surface temperature (SST) for 30 years ($1941{\sim}1970$) at 9 coastal stations in the Tsushima Current and the Kuroshio regions by means of harmonic analysis, correlation analysis, and spectral analysis. The fluctuations of annual mean and amplitude are 0.3 to $0.7^{\circ}C$, and those of annual phase are 3 to 4 days. The SST anomalies are about $1^{\circ}C$, and they are relatively large in summer and winter than in spring and fall. The SST anomalies in the Tsushima Current and the Kuroshio regions are related with each other. The predominant periods of SST anomalies differ slightly from station to station. The quasi-biennial (26 months) and pole tide (14 months) oscillations are found in the spectra of SST anomalies.

• Journal of Astronomy and Space Sciences
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• v.29 no.4
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• pp.329-336
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• 2012

Korea Astronomy and Space Science Institute researchers have installed and operated magnetometers at Bohyunsan Observatory to measure the Earth's magnetic field variations in South Korea. In 2007, we installed a fluxgate magnetometer (RFP-523C) to measure H, D, and Z components of the geomagnetic field. In addition, in 2009, we installed a Overhauser proton sensor to measure the absolute total magnetic field F and a three-axis magneto-impedance sensor for spectrum analysis. Currently three types of magnetometer data have been accumulated. In this paper, we use the H, D, Z components of fluxgate magnetometer data to investigate the characteristics of mid-latitude geomagnetic field variation. To remove the temporary changes in Earth's geomagnetic filed by space weather, we use the international quiet days' data only. In other words, we performed a superposed epoch analysis using five days per each month during 2008-2011. We find that daily variations of H, D, and Z shows similar tendency compared to previous results using all days. That is, H, D, Z all three components' quiet intervals terminate near the sunrise and shows maximum 2-3 hours after the culmination and the quiet interval start from near the sunset. Seasonal variations show similar dependences to the Sun. As it becomes hot season, the geomagnetic field variation's amplitude becomes large and the quiet interval becomes shortened. It is well-known that these variations are effects of Sq current system in the Earth's atmosphere. We confirm that the typical mid-latitude geomagnetic field variations due to the Sq current system by excluding all possible association with the space weather.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
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• 1998.11a
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• pp.143-147
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• 1998

Autonomic and EEG responses of 38 college students were studied during 60-sec long presentation of International Affective Picture System (IAPS )slides evoking, according to subjective reports, negative (disgust, sadness, surprise) and positive (happiness, exciting) emotional. states. Observed were significant heart rate (HR) deceleration, large skin conductance responses (SCR), moderate respiration frequency slowing, reduction of frontal (F 3, F 4 ) and occipital (O 1, O 2 ) fast alpha, and increases of theta, delta and beta relative spectral power values during the first 30 sec of exposure of IAPS pictures. Analysis carried out to differentiate emotion categories according to autonomic responses indicated that observed HR deceleration was larger in magnitude in surprise and sadness than in disgust, SCR amplitude higher in sadness than in disgust. EEC showed significant differences in theta (F 3, F 4 ) and delta (O 1) power increase in disgust vs. happiness, fast alpha (F 3, F 4 ) power was lower in surprise than in happiness, and slow beta power higher. in happiness than in disgust (0 1). Despite some differences. observed within discrete emotion conditions, overall responses pattern of monitored parameters exhibited similar profiles with few variations, most. obvious. in disgust state, which suggests that affective visual stimulation elicits stereotypical responses in a given passive viewing paradigm. However, the magnitude of physiological responses may vary to certain extent across discrete emotional states making it possible to differentiate among particular experimentally-induced emotional states, e.g., disgust vs. sadness by ANS responses or disgust vs. happiness by EEG measures.

• Korean Journal of Remote Sensing
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• v.35 no.6_4
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• pp.1417-1424
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• 2019

Recently, disaster accidents have occurred frequently over the world, and disaster have been continuously studied using remote sensing due to large scale and hard-to-reach features. The collapse of Laos Xe pian-Xe namnoy dam in 2018 also caused a lot of human and economic damage. This study's purpose is to change detect water system due to the collapse of Xe pian-Xe namnoy dam in Laos and to derive areas where future flooding is expected. The water system is extracted from each image of KOMPSAT-5 before and after the dam collapse in order to quantitatively change detect in the water system. The result of the water system area increased more than 10 times after the dam collapse. In addition, it is confirmed that the newly created water system is thickly created in areas of low altitude area. This study result can be used in the future to systematize the pre-response to abnormalities and issues in existing operating dams. And then, if combined with other remote sensing data, more diverse and specific results could be obtained.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.9A
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• pp.983-990
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• 2004

In this paper, we calculated the input impedance of the power line communication(PLC) networks using medium voltage power line. First of all, we proposed input and output teoninal model of PLC network, and calculated the input impedance applying the attenuation constants by radiation loss, conductor loss, dielectric loss. From the calculation result, we knew that the attenuation by radiation loss was largest, and the input impedance appears like a standing wave fonn with a fixed cycle because the high reflection at the input terminal for the characteristic impedance of the power line is very large. And also the cycle of input impedance depends on the coaxial cable length, and the amplitude depends on the characteristic impedance of power line and losses. From the measurement result, calculated result was very similar to the measured result.

• Proceedings of the KWS Conference
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• 2009.11a
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• pp.32-32
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• 2009

Electric Resistance Welding (ERW) process is the most efficient process to manufacture the linepipe. To develop the high performance ERW linepipe using the high strength and the high alloy steels, the modulation of input power waveform such as sinusoidal waveform is introduced because the conventional ERW technology is not sufficient enough to produce the high quality linepipe due to its strength and high alloy contents (high Ceq). In this article, the material used for the experiment was API X60 with 8.2mm thickness, and ERW simulator at POSCO was used to develop a waveform control system for the power modulation. The frequency of power modulation was varied from 50Hz to 150Hz with the fixed amplitude of ${\pm}2%$ power. The non-modulated power input and the modulated power input cases are conducted to demonstrate the variation of the narrow gap length and the arcing frequency due to power modulation. From results of the non-modulated power input case, the excessive power causes the longer narrow gap length and the low arcing frequency due to the large heat input and the strong electro magnetic force that increase the weld defect. On the contrary, the small narrow gap length and the high arcing frequency reduce the weld defect. After modulating the power input with 50Hz and 100Hz at the fixed power, the arcing frequency increases, but the narrow gap length does not change much. The high arcing frequency prevents the formation of weld defect because the sweeping frequently cleans the oxides on the narrow gap edges. As a result, the manufacturing window can be expanded by the power modulation that provides the stable ERW process for the quality improvement of the linepipe made from the high strength/high alloy steels.