• Computational Structural Engineering
• /
• v.16 no.1
• /
• pp.73-76
• /
• 2003

• Proceedings of the KSEEG Conference
• /
• 2000.04b
• /
• pp.182-183
• /
• 2000

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.32 no.6A
• /
• pp.347-354
• /
• 2012

In this study, the equations of torsional and warping constants of a I-shaped plate girder with sine corrugated web are suggested. Because of geometric characteristics of the section, a I-shaped plate girder with corrugated web shows high out-of-plane stiffness, shear strength, and torsional stiffness. Torsional constant and warping constant definitely affect lateral-torsional buckling loads. Therefore, exact estimation of the sectional properties is quite important. But, it is difficult to estimate these properties by former methods. So, this study was focused on suggestion of the rational equations to calculate torsional and warping constants. In order to investigate the effects of geometric characteristics of sine-corrugated webs on torsional stiffness and warping torsional constant, finite element analyses for pure torsional behavior and warping torsional behavior of I-shaped plate girders were performed. By regression analyses of the analytical results, rational equations of the torsional constant and warping constant were suggested. Suggested equations for the properties were validated based on the analytical results of lateral-torsional buckling of simply supported I-shaped plate girder. By suggested equations, torsional and warping constants of I-shaped plate girders with a sine-corrugated web can be rationally estimated and more exact lateral-torsional buckling load can be simply calculated.

• Fire Science and Engineering
• /
• v.34 no.4
• /
• pp.1-6
• /
• 2020

In this study, the authors measured voltage and current waveforms in real time during a serial arc discharge. The analysis results of the arc discharge radiation patterns exhibited intermittent discharge, arc growth, creation of a heat generating area, occurrence of plume, and formation of a red heat area, which proceeded in that order. When the serial arc discharge was introduced, the current and voltage waveforms exhibited periodicity as sine waves. It was also observed that a restriking transient voltage occurred when the waveform changed from positive (+) to negative (-) and vice versa. When the discharge proceeded, the amount of heat generated for 1 s and 600 s was approximately 0.317 mJ, and 190 mJ, respectively. The duration of the short circuit was approximately 1.66 ms, and in the case of the voltage waveform, it was evident that the electric potential increased to 49.9 V in the same cycle. Furthermore, when the discharge proceeded, the effective value (RMS value) of the current was approximately 1.72 A with a maximum current of approximately 2.53 A, whereas the effective value of the voltage was approximately 42.8 V with a maximum of approximately 208 V.

• Geophysics and Geophysical Exploration
• /
• v.23 no.1
• /
• pp.38-49
• /
• 2020

Full-waveform inversion (FWI) is an optimization process of fitting observed and modeled data to reconstruct high-resolution subsurface physical models. In acoustic FWI (AFWI), pressure data acquired using a marine streamer has mainly been used to reconstruct the subsurface P-wave velocity models. With recent advances in marine seismic-acquisition techniques, acquiring multi-component data in marine environments have become increasingly common. Thus, AFWI strategies must be developed to effectively use marine multi-component data. Herein, we proposed an AFWI strategy using horizontal and vertical particle-acceleration data. By analyzing the modeled acoustic data and conducting sensitivity kernel analysis, we first investigated the characteristics of each data component using AFWI. Common-shot gathers show that direct, diving, and reflection waves appearing in the pressure data are separated in each component of the particle-acceleration data. Sensitivity kernel analyses show that the horizontal particle-acceleration wavefields typically contribute to the recovery of the long-wavelength structures in the shallow part of the model, and the vertical particle-acceleration wavefields are generally required to reconstruct long- and short-wavelength structures in the deep parts and over the whole area of a given model. Finally, we present a sequential-inversion strategy for using the particle-acceleration wavefields. We believe that this approach can be used to reconstruct a reasonable P-wave velocity model, even when the pressure data is not available.

• Journal of the Korean Institute of Telematics and Electronics
• /
• v.15 no.1
• /
• pp.1-4
• /
• 1978

This paper described the establishment of the basic data for the design of the transducer for the detection of plethysmogram, the structure of pulsimeter utilizing the designed transducer and the clinical usefulness of detected waveform of the optical detection method can be utilized as an information of cardiovascular system as physiological theoretical waveform of aorta, and derivative of plethysmogram by piezo electric elements clearly shows the information of incisura which does not appear at the old age and this makes the measuring of ejection time to be easy. The ejection time of average for 42 persons shows 0.324 $\pm$ 0.027 sec. and this value is in good agreement with the theoretical value, and the possibility of measuring the velocity of pulse conduction has been studied.

• Proceedings of the IEEK Conference
• /
• 2000.06b
• /
• pp.48-51
• /
• 2000

We proposed the new driving waveform which has changed the waveform of sustain division to improve luminous efficiency in plasma display panel. This sustain waveform is to add the ramp to the rectangular waveform, resulting in self-erasing discharge in the falling edge region. The proposed waveform has improved the luminous efficiency of 30％ even in low driving frequency(25kHz), whereas the conventional driving waveform using the self-erasing discharge can improve the luminous efficiency only in high driving frequency( >150kHz). Front the results of this paper, we hope that the variety study on frequency and duty ratio, ramp waveform will increase the luminous efficiency.

• Journal of Ocean Engineering and Technology
• /
• v.6 no.1
• /
• pp.122-130
• /
• 1992

The effect of loading waveform on elevated temperature low-cycle fatigue crack growth behavior in a SUS 304 stainless steel have been investigated under symmetrical trangular (fast-fast), trapezoidal and asymmetrical(fast-slow, slow-fast) waveforms at 650.deg. C. It was found that the crack growth rate in fast-slow loading waveform appeared to be higher a little and the crack growth rate in slow-fast loading waveform much higer than that in fast-fast loading waveform, and difference in crack growth rate between fast-show and slow-fast waveforms nearly didn't appear in the region of da/dN>10/sup -2/ The crack growth rate in the trapezoidal loading waveform with t/sub h/=500sec appeared to be faster than that in slow(500sec)-fast(1sec). In addition, parameter modified J-integral could be considered as useful parameter for fatigue crack growth rate in all waveforms. The result obtained are as follow. da/dN=4.91*10/sup -3/ (.DELTA. J/sub c/)/sup 0.565/.

• Journal of Korean Society of Steel Construction
• /
• v.15 no.1
• /
• pp.33-40
• /
• 2003

There are two basic concepts about concerning the buckling analysis of a buried pipe. One concept considers the soil around the pipe asn elastic continuum mediaum. The other concept holds that the pipe is sup ported by an elastic spring, which replaces the effects of the surrounding soil (the Winkler model). Theise buckling analysis is based on plane analysis, without considering the corrugation effect and the length effect. This paper thus presents a parametric study using the Finite Element Method (FEM) for the Winker model and proposes a buckling strength formula after examining a 3D analysis considering the corrugation effect and the length effect, thatwhichhelp in estimating the critical buckling strength of such CSP

• Journal of the Korean Society of Hazard Mitigation
• /
• v.3 no.1 s.8
• /
• pp.123-131
• /
• 2003

An experiment was carried out to investigate the mechanical behaviour of the circular hollow section reinforced concrete member with internal corrugated steel tube. A specimen, 50cm in diameter and 340cm in length, was made and tested by 3 points bending. The test load was increased slowly (quasi static) to the failure or unacceptable deformation. During the test, lateral displacement at mid point and longitudinal displacement of extreme fiber on compressive and tensile side of the specimen were measured. The measured data were analysed and compared with calculated results for the equivalent member without inserted corrugated steel tube. The comparison shows that the flexural strength and ductility of hollow section reinforced concrete members can be improved by inserting corrugated steel tubes inside.