• Proceedings of the KSR Conference
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• 2010.06a
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• pp.1444-1451
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• 2010

This paper aims for proposed the deflection limit on vibration serviceability of high-speed railway bridges considering the exposed time duration when a train passes a railway bridge. For this purpose, bridge-train transfer function was derived and bridge-train interaction analysis was performed by using the derived function. The vertical acceleration signals of passenger cars obtained from bridge-train interaction analysis were compared with them from the bridge-train transfer function by moving constant force analysis. Therefore it was estimated possible to induce the comfort deflection limit of railway bridge by using bridge-train transfer function. The deflections by moving force of single span bridge and continuous bridge were assumed as sine and haversine wave. The deflection limit on vibration serviceability of high-speed railway bridges considering the exposed time duration can be expanded using bridge-train transfer function and bridge comfort limit considering serviceability due to bridge vibration. And it was compared to other allowable deflection limits of railway bridge design specifications.

• Proceedings of the Korea Information Processing Society Conference
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• 2002.04b
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• pp.1239-1242
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• 2002

In this paper, the implementation of MAI(multiple access interference)-cancelled SSMA(spread spectrum multiple access) system using orthogonal carriers was presented. Employing the pseudo periodic spreading codes and orthogonal carriers frequency offset, proposed system have the features no MAI during a certain local time-duration. Spreading signals designed by pseudo periodic method and repetition, have zero correlation duration(ZCD) by orthogonal frequency shift method. The SSMA modem has been designed and implemented using surface-acoustic-wave(SAW) device as the matched filter of receiver. The effects of frequency offset on stability have been evaluated using computer simulation.

• Steel and Composite Structures
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• v.17 no.6
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• pp.891-906
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• 2014

This study aims to present a three dimensional finite element model to investigate the wave propagation in a concrete filled steel tubular column (CFSC) due to transient impact load. Both the concrete and steel are regarded as linear elastic material. The impact load is simulated by a semi sinusoidal impulse. Besides the CFSC models, a concrete column (CC) model is established for comparing under the same loading condition. The propagation characteristics of the transient waves in CFSC are analyzed in detail. The results show that at the intial stage of the wave propagation, the velocity waves in CFSC are almost the same as those in CC before they arrive at the steel tube. When the waves reach the column side, the velocity responses of CFSC are different from those of CC and the difference is more and more obvious as the waves travel down along the column shaft. The travel distance of the wave front in CFSC is farther than that in CC at the same time. For different wave speeds in steel and concrete material, the wave front in CFSC presents an arch shape, the apex of which locates at the center of the column. Differently, the wave front in CC presents a plane surface. Three dimensional effects on top of CFSC are obvious, therefore, the peak value and arrival time of incident wave crests have great difference at different locations in the radial direction. High-frequency waves on the waveforms are observed. The time difference between incident and reflected wave peaks decreases significantly with r/R when r/R < 0.6, however, it almost keeps constant when $r/R{\geq}0.6$. The time duration between incident and reflected waves calculated by 3D FEM is approximately equal to that calculated by 1D wave theory when r/R is about 2/3.

• Earthquakes and Structures
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• v.14 no.6
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• pp.577-587
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• 2018

The quantitative assessment of the seismic collapse risk of a structure requires the usage of an optimal intensity measure (IM) which can adequately characterise the severity of the ground motion. Research suggests that the average spectral acceleration ($Sa_{avg}$) may be an efficient and sufficient alternate IM as compared to the more traditional first mode spectral acceleration, $Sa(T_1)$, particularly during seismic collapse risk estimation. This study primarily presents a comparative evaluation of the sufficiency of the average spectral acceleration with respect to ground motion duration, and secondarily assesses the impact of ground motion duration on collapse risk estimation. By assembling a suite of 100 historical ground motions, incremental dynamic analysis of 60 different inelastic single-degree-of-freedom (SDF) oscillators with varying periods and ductility capacities were analysed, and collapse risk estimates obtained. Linear regression models are used to comparatively quantify the sufficiency of $Sa_{avg}$ and $Sa(T_1)$ using four significant duration metrics. Results suggests that an improved sufficiency may exist for $Sa_{avg}$ when the period of the SDF system increases, particularly beyond 0.5, as compare to $Sa(T_1)$. In reference to the ground motion duration measures, results indicated that the sufficiency of $Sa_{avg}$ is more sensitive to significant duration definitions that consider almost the full wave train of an accelerogram ($SD_{a5-95}$ and $SD_{v5-95}$). In order to obtain a reduced variability of the collapse risk estimate, the 5-95% significant duration metric defined using the Arias integral ($SD_{a5-95}$) should be used for seismic collapse risk estimation in conjunction with $Sa_{avg}$.

• Journal of Korean Medicine Rehabilitation
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• v.30 no.2
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• pp.95-103
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• 2020

Objectives This report aimed to review literatures using extracorporeal shock wave with syndrome differentiation theory. Methods By March 3, 2020, five foreign electronic databases (PubMed, Web of Science, Cochrane Library, EMBASE, CAJ) and six Korean medical electronic databases (KMBASE, KISTI, KISS, NDSL, DBpia, RISS) were reviewed with the key word 'extracorporeal shock wave' and 'syndrome differentiation'. We did not impose restrictions on age, gender, treatment methods, duration, results and the design of the paper. Results Twelve papers met the inclusion criteria. Seven papers used extracorporeal shock wave lithotripsy with syndrome differentiation theory and six out of seven papers treated urologic stones using extracorporeal shock wave lithotripsy. The other five papers used extracorporeal shock wave therapy with syndrome differentiation theory and four of them treated musculoskeletal disorders. However, the data of the characteristics of extracorporeal shock wave was insufficient. Conclusions After thorough review, it is considered to be meaningful to treat urologic stones and musculoskeletal disorders using extercorporeal shock wave with syndrome differentiation theory. However, some of the literatures were limited in their feasibility and reliability in terms of research design. In addition, the data regarding the strength of the extracorporeal shock wave applied on each acupoints was insufficient. Therefore, further study on the use of extracorporeal shock wave on acupoints should be conducted.

• Proceedings of the Korean Society of Coastal and Ocean Engineers Conference
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• 2002.08a
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• pp.1-13
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• 2002

For design of maritime structure, it is necessary to evaluate the effect and stability of the structure against wave action. Laboratory model experiments and their empirical formulas are mainly used to estimate those at present, although empirical formulas have a problem of accuracy and hydraulic experiments of cost and duration. In addition, performance-based design, which may be popularized as a new design concept in the near future, requires much more information than that obtained by empirical formulas and laboratory tests. Thus, numerical simulation may become more important hereafter for structure design. (omitted)

• International Journal of Naval Architecture and Ocean Engineering
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• v.6 no.4
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• pp.1148-1159
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• 2014

Different procedures for estimation of the extreme global wave hydroelastic responses in ships are discussed. Firstly, stochastic procedures for application in detailed numerical studies (CFD) are outlined. The use of the First Order Reliability Method (FORM) to generate critical wave episodes of short duration, less than 1 minute, with prescribed probability content is discussed for use in extreme response predictions including hydroelastic behaviour and slamming load events. The possibility of combining FORM results with Monte Carlo simulations is discussed for faster but still very accurate estimation of extreme responses. Secondly, stochastic procedures using measured time series of responses as input are considered. The Peak-over-Threshold procedure and the Weibull fitting are applied and discussed for the extreme value predictions including possible corrections for clustering effects.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2001.05a
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• pp.234-239
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• 2001

The subsidence characteristics of artificial reef in the unsteady flow such as tidal flow were investigated. The scour and subsidence characteristics were confirmed in the steady flow field, wave field and steady flow-wave field. In a main study, the interaction of Flow-Sediment Movement-Structure Behavior and scour.subsidence mechanism were discussed in the unsteady flow field and the unsteady flow-wave field. Most of all, the continuous artificial reef subsidence from the scour was occurred by periodic behavior of artificial reef. This behavior is result from the asymmetric ground, and is influenced by maximum velocity, duration time and direction of flow.

• Journal of Yeungnam Medical Science
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• v.18 no.2
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• pp.267-276
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• 2001

Background: P wave dispersion(PWD) is defined as the difference between the maximum and minimal P wave duration in any of the 12 leads of the surface ECG. The prolongation of atrial conduction time and the inhomogeneous propagation of sinus impulse are known electrophysiologic features in patients with paroxysmal atrial fibrillation(PAF). The purpose of this study was to determine the role of P wave dispersion for the prediction of PAF and to evaluate the effectiveness of prophylactic antiarrhythmic therapy. Materials and Methods: The study population included 20 patients with a history of idiopathic PAF and 20 age and sex matched healthy control subjects. We measured the maximum P wave duration(P maximum) and P wave dispersion from 12 lead ECG. Results: P maximum and P dispersion in idiopathic PAF were significantly higher than normal control group($97.2{\pm}12$, $48.5{\pm}9$ msec vs, $76.5{\pm}11$, $21{\pm}8$ msec, respectively p<0.001, <0.001). After 12-month follow up period P maximum and P dispersion were significantly reduced than those of initial state($77.2{\pm}13$, $26.4{\pm}9$ msec vs. $97.2{\pm}12$, $48.5{\pm}9$ msec, respectively p<0.001,<0.001). Conclusion: P dispersion and P maximum were significantly different between patients with idiopathic PAF and healthy control group. Those are easily accessible, non-invasive simple electrocadiographic markers that could be used for the prediction and prognostic factors of idiopathic PAF.

• Journal of Acupuncture Research
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• v.18 no.4
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• pp.116-124
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• 2001

Background and Objetive : The aim of this study was to investigate the effect of various electroacupuncture stimulation on NADPH-diaphorase in cerebral cortex, brain stem, cerebellum of spontaneously hypertensive rats. Materials and Methods : We evaluated the changes of NADPH-d-positive neurons using a histochemical method. The staining intensity of NADPH-d-positive neurons was assessed in a quantitative fashion using a microdensitometrical method based on optical density by means of an image analyzer. Results and Conculsion : The average optical density of NADPH-d-positive neurons of 100 Hz (bipolar square wave 0.2 ms duration and 100 Hz frequency) electroacupuncture treatment group significantly increased in most cortical areas comparison between the manual acupuncture and 2 Hz (bipolar square wave 0.2 ms duration and 2 Hz frequency) electroacupuncture groups. In the brain stem, the optical density of NADPH-d-positive neuron at only superficial gray layer of the superior colliculus area was same as cerebral cortex. We conclude that the morphological evidence for NADPH-d-positive neurons may be have regional change in cerebral cortex brain stem and cerebellum according to various electroacupuncture stimulations.