• Sleep Medicine and Psychophysiology
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• v.14 no.1
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• pp.5-12
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• 2007

Sleep changes substantially with age. There is a phase advance in the circadian sleep cycle and increased waking after sleep onset. The elderly people wake more frequently during the night and experience fragmented sleep and excessive daytime sleepiness. The prevalence of sleep disorders increases with age, and the composition of sleep disorders in the elderly differs from that in the young. The most frequently encountered sleep disorders are psychophysiologic insomnia, sleep disturbance due to dementia, sleeprelated respiratory disorder, restless legs syndrome and periodic limb movement disorder, and REM sleep behavior disorder. To treat the elderly sleep problem appropriately, it is important to know how sleep pattern changes as we age and to understand the cause of sleep-related symptoms. This article will review the sleep physiology and common sleep disorders in the elderly.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2003.10a
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• pp.293-298
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• 2003

The rockfall protection fences are installed to reduce rockfall damage in roads side slopes. The energy absorbing capacity of widely used rockfall protection fences is about 50kJ, But in many cases, rockfall protection fences are easily damaged even by a low level of rockfall energy. The objective of this paper is to verify the energy absorbing capacity of rockfall protection fences and investigate the behavior of them by rockfall. The LS-DYNA3D, a finite elements analysis program for dynamic movement of three dimensional objects, is used to perform the numerical simulations. In the result it is shown that rockfall protection fences absorb half of standard absorbing energy or less than it. It is inadquate for the rockfall protection fences to perform the principal function. To improve the performance of the fences, new rockfall proctection fence is proposed and numerical simulation is performed.

• Proceedings of the KSR Conference
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• 2006.11b
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• pp.322-327
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• 2006

Banwol bridge with steel plate girder and Pyongtaek bridge with PSC bos girder have been operated maintenance measuring system by the Seoul-Chonan of Kyongbu express railway. By analyzing the theoretical and experimental values of design load for these two bridge, the establishment of reference maintenance for measuring items was deduced from research. Two materials, steel and concrete plates, were considered as the upper structure. Actual measurement data for the behavior under speed, structural analysis results, and the presented references were analyzed and used to set up the reference establishment. The measuring items are stress(strain), displacement, dynamic acceleration, expansion movement, and dynamic frequency. The maintenance reference was established by comparing analytical and measuring values of the five items with respect to structural state class.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2009.05b
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• pp.21-24
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• 2009

This study deals with the application of USN wireless inclinometer sensor for earth retaining structure safety measurement, The application of wireless inclinometer sensor has great advantage about real-time monitoring of earth retaining structure, It allows a construction manager to monitor movement data from anywhere connected through internet during the process of excavation for substructures of buildings, To validate the applicability of the wireless inclinometer sensor. laboratory and field tests have been performed, The results have shown that the measured values of wireless inclinometer sensor represent the behavior of H-pile well, Both convenience of sensor installation and real-time monitoring of earth retaining structure are confirmed, The proposed wireless measurement system provides a good basis for exact measurement of temporary substructures, More measurements and application are expected for the other excavation sites with various conditions.

• Journal of the Korean GEO-environmental Society
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• v.14 no.10
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• pp.17-27
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• 2013

This paper explores stress release induced by unloading in dry sand. A series of model tests were carried out to measure stresses developed in testing sand during loading and those released during unloading for different boundary conditions. It was found that stress in the sand increased linearly with applied load. At the onset of unloading, almost no stress release was observed. Significant stress release took place when the shear stress in the sand induced by unloading exceeded the frictional resistance and caused movement of sand particles. The initiation and the magnitude of stress release depend on the stress condition prior to unloading, the decrease of external load, and also the frictional resistance in sand. A new conceptual stress-release model was next developed based on the model test results by considering the fundamental frictional behavior of granular materials.

• Proceedings of the Korean Institute of Interior Design Conference
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• 2005.05a
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• pp.168-171
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• 2005

A movement of visitor is a practical means that provides a spatial arrangement of exhibits and validity to that principle. Thus, an exhibition of a museum cannot be completed by an intrinsic value of exhibition itself. Rather, the meaning and value of exhibition can be genuinely evaluated by a visitor's experience and reactions. Therefore, focusing on an correlation between exhibits' spatial configuration and a behavior in a museum, this thesis will establish effective indicators of analysis and their validity in predicting a frequency of visitor's visit depending on the structural form of exhibition space.

• Journal of Information Processing Systems
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• v.6 no.4
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• pp.521-536
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• 2010

Spatio-temporal patterns extracted from historical trajectories of moving objects reveal important knowledge about movement behavior for high quality LBS services. Existing approaches transform trajectories into sequences of location symbols and derive frequent subsequences by applying conventional sequential pattern mining algorithms. However, spatio-temporal correlations may be lost due to the inappropriate approximations of spatial and temporal properties. In this paper, we address the problem of mining spatio-temporal patterns from trajectory data. The inefficient description of temporal information decreases the mining efficiency and the interpretability of the patterns. We provide a formal statement of efficient representation of spatio-temporal movements and propose a new approach to discover spatio-temporal patterns in trajectory data. The proposed method first finds meaningful spatio-temporal regions and extracts frequent spatio-temporal patterns based on a prefix-projection approach from the sequences of these regions. We experimentally analyze that the proposed method improves mining performance and derives more intuitive patterns.

• Proceedings of the KIEE Conference
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• 1996.11a
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• pp.267-269
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• 1996

In this work, the influence of wire type conducting particles on the insulation reliability of GIS has been systematically investigated when outer electrode was dielectric coated by epoxy resin. For this purpose, coaxial cylinder-type electrode was adopted in 362 kV chamber and various size of Cu conducting particle was used and different gas pressure was applied. To prove the coating effect on the gas insulation, different thickness of epoxy coated outer electrode have been considered and the lift-off voltage and flashover voltage have been analyzed. The results show that the dielectric coated electrode has an remarkable influence on the reducing particle behavior in GIS system and enhancing the GIS insulation reliability.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2010.05a
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• pp.725-727
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• 2010

For simulation of Boat motion, pitch, motion element of roll and yaw direction could simulated. The combination of the marine use various multi sensor surveillance system technology with the development of servo motion control algorithm and gyro sensor in six freedom motion is implemented to analyze the movement response. The stabilization of the motion control is developed and Nano driving Precision Pan-Tilt/Gimbal system is obtained from the security positioning cameras with ultra high speed device is used to carry out the exact behavior of the device.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1998.06a
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• pp.95-101
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• 1998

The steel door inner was manufactured via a new route, tailored blanking process, to remove hinge reinforcement parts, using thicker panels laser welded, instead. It is very important, first of all, in this process, to design optimum configuration of tailored blanks and determine the optimum process control for the stamping. Generally, it was found that the severe deformation reduction behavior during stamping in the thinner panel around weld line caused cracks and the other troubles in formability. It is our purpose of this investigation to introduce how the process control parameters, such as tailored blank configuration, size, location in the die, the position of weld line, BHF, bead configuration, work on the formability. In addition, causes of cracks and movement of weld line after forming were analyzed and compared with computer simulation work.