• Journal of applied mathematics & informatics
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• v.29 no.3_4
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• pp.891-900
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• 2011

In this paper, we study the impulsive dynamic systems on time scales with initial time difference. By employing cone-valued Lyapunov functions, some comparison theorems and several practical ${\phi}_0$-stability criteria for impulsive system on time scales with initial time difference are obtained.

• Journal of the Korean Academy of Clinical Electrophysiology
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• v.10 no.2
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• pp.31-35
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• 2012

Purpose : The purpose of this study was to investigate the effect of kinematic variables by analysis of a gait in older. Methods : This study selected nine in older adults with osteoarthritis. The Kinematic variables during walk were compared analyzed using motion analysis. Results : The findings of this study are as follows. Stance time showed significant difference within-subject groups and interaction within-subjects and time. The swing and stride time showed a no significant interaction within-subjects and time. Swing time showed a no significant difference according to time and within-subjects. Stride time showed a significant difference according to time. But, stride time showed a no significant difference according to within-subjects. Conclusion : These findings of this study indicate that when the patients with total knee arthroplasty decreased stability. Therefore, stance and stride time showed increase when walking, because to decrease the weight bearing that is delivered to knee. And swing time showed decrease.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2003.05a
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• pp.95-98
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• 2003

This paper presents the results of field experiment to apply the difference of setting tine method using super retarding agent for reducing hydration heat of mass concrete of foundation. According to the results, as the properties of fresh concrete, base concrete satisfies aimed slump and air content, and there is no difference of slump and air content with mixture of super retarding agent. The mixing ratio of super retarding agent is determined for setting time to be retarded by 12 hours in comparison with base concrete, but because the temperature of the air and concrete is low, the difference of setting time is retarded to 24 hours. In man concrete of foundation to which the difference of setting time method is applied, crack by hydration heat is not seen because the lower concrete of super retarding agent generates heat after generation of hydration heat of the upper concrete.

• Journal of Advanced Navigation Technology
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• v.24 no.3
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• pp.218-223
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• 2020

There are communication methods that guarantees real-time and method of performing the simultaneous acquisition through the synchronized multi-channels to improve the reliability of the telemetry system. Such synchronized systems need to be verified to confirm the simultaneous measurement performance of channels. In this paper, we propose a method to measure the time difference between synchronized channels in a telemetry system through simultaneous acquisition performance test. The simulation signal is applied for measurement and the difference between the sampling period and the simulation signal period is defined as the concept of time resolution. The principle of checking the measurement time difference between channels through time resolution was explained. In addition, the proposed principle was verified through simulation in the situation when measurement time difference may occur. And a procedure for identifying a measurement time difference in an actual telemetry system is described.

• Journal of the Korean Society of Physical Medicine
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• v.5 no.4
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• pp.577-585
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• 2010

Purpose : This study was to evaluate gait velocity and stance time on 5 conditions in elderly women and elderly women with LBP. The subjects were 70's generation. Methods : The subjects are 20 divided into 2 groups. They measured gait velocity, stance-time. The 5 conditions were normal gait, 10cm obstacle gait, 25cm obstacle gait, dual 10cm obstacle gait, dual 25cm obstacle gait. The experimental period was between 2008/12 and 2009/2. Statistical analysis was used Repeated measurement for difference between conditions, independent t-test for difference in two groups. Subjects were countdown from 50 during dual task gait. Results : The results were as follow: there were significantly difference 10cm obstacle velocity, dual 10cm obstacle velocity in two group. The others were not significantly differences. Velocity and stance-time were significantly difference in control group. In dual 25cm obstacle gait, velocity was difference of normal gait. Stance-time was difference in 25cm obstacle gait, and dual 25cm obstacle gait. In Experimental group, velocity and stance-time were not significantly difference. But measured value of velocity was gradually decreased and stance time was increased. Conclusion : These results indicate that elderly people with LBP women are reduced gait ability in dual task, and obstacle condition. So they need to prevent falling in dual task, and obstacle gait and to train obstacle/dual tak gait.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.4
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• pp.1895-1899
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• 2012

Formulation of finite difference method for analyzing consolidation were carried out. It can be seen that the differences in settlement with time obtained by FDM and Terzaghi method are diminished by fine discretization of time increment. Excess pore pressures predicted by the derived finite difference equation were same as those calculated by Olson's method. Predicted time-settlement behavior from the derived finite difference method were almost same as those calculated by Terzaghi's method and Olson's method. Analysis results obtained from the assumed multi-step time dependent loading are thought to be reasonable.

• Journal of Information Technology Applications and Management
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• v.22 no.3
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• pp.105-114
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• 2015

This paper presents a fast Time Difference of Arrival (TDOA) estimation for sound source localization. TDOA is the time difference between the arrival times of a signal at two sensors. We propose a partial cross correlation method to increase the speed of TDOA estimation for sound source localization. We do this by predicting which part of the cross correlation function contains the required TDOA value with the help of the signal energies, and then we compute the cross correlation function in that direction only. Experiments show approximately 50% reduction in the cross correlation computation time thereby increasing the speed of TDOA computation. This makes it very relevant for real world surveillance.

• Journal of Korean Clinical Health Science
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• v.8 no.1
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• pp.1386-1397
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• 2020

Purpose: To examine the effectiveness of various treatments; bifocal spectacles, orthokeratology, atropine, and time spent in outdoors; in slowing down the myopia progression for Asian adolescents (6-18age). Methods: The research focused on examining the most effective treatment in controlling myopia based on the literature sources that have been published. Through meta-analysis of various research papers that already has been done in this field, a lot of data was collected. For each treatment, the difference in axial length and spherical equivalent over time was measured and recorded. To quantitatively record the difference, both axial length and spherical equivalent was determined by value of control group value of treatment group. The paper compared the effectiveness of each treatment based on the data that was measured. Results: Adolescents who chose to spend time outdoors in order to slow down myopia progression had axial length difference of 0.03 mm and spherical equivalent difference of 0.17 D. Adolescents that used atropine had axial length difference of 0.36 mm and spherical equivalent difference of 0.92 D. Bifocal spectacle resulted in axial length difference of 0.21 mm and spherical equivalent difference of 0.59 D, and for orthokeratology 0.23 mm and 0.04 D, respectively. Axial length wise, myopia was most controlled by the atropine since there was a greatest difference between the group that got the treatment and the group that did not have the treatment. According to the spherical equivalent difference data, myopia was most controlled by atropine. Conclusion: Atropine showed the most effective result in controlling myopia among the four treatment. Again, compared to other three treatment, using atropine appeared to have greatest ability in slowing down myopia progression since adolescents who were treated with atropine had greatest difference from adolescents in the control group that had the same condition but didn't get the treatment. However, every treatment was only used for 2 or 3 years which is quite short time period to measure the long term effect of the four treatments. Also, since atropine is a pharmaceutical method to control myopia, it may harm adolescents' eyes compared to optical or environmental treatment.

• Journal of Positioning, Navigation, and Timing
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• v.9 no.4
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• pp.397-403
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• 2020

In order to synchronize a remote system time to the reference time like Coordinated Universal Time (UTC), it is required to compare the time difference between the two clocks. The time comparison data may have some outliers and the time synchronization performance can be significantly degraded if the outliers are not removed. Therefore, it is required to employ an effective outlier detection algorithm for keeping high accurate system time. In this paper, an outlier detection method is presented for the time difference data of GNSS time transfer receivers. The time difference data between the system time and the GNSS usually have slopes because the remote system clock is under free running until synchronized to the reference clock time. For investigating the outlier detection performance of the proposed algorithm, simulations are performed by using the time difference data of a GNSS time transfer receiver corrected to a free running Cesium clock with intentionally inserted outliers. From the simulation, it is investigated that the proposed algorithm can effectively detect the inserted outliers while conventional methods such as modified Z-score and adjusted boxplot cannot. Furthermore, it is also observed that the synchronization performance can be degraded to more than 15% with 20 outliers compared to that of original data without outliers.

• Journal of the Korea Society for Simulation
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• v.5 no.1
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• pp.81-90
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• 1996

In this paper, we propose a new events ordering mechanism for the optimistic distributed simulation of DEVS models. To simulate DEVS models in a distributed environment, a synchronization protocol is required for correct simulation. Time Warp is the most well-known optimistic synchronization protocol for distributed simulation. However, employing the Time Warp protocol in distributed simulation of DEVS models incurs events ordering problem due to the semantic difference between Time Warp and DEVS, Thus, to resolve such semantic difference, we devise the time-and-priority-stamp and $\varepsilon$ -delay schemes. The proposed schemes can order simultaneous events correctly in Time Warp-based distributed simulation of DEVS models.Time Warp and DEVS, Thus, to resolve such semantic difference, we devise the time-and-priority-stamp and $\varepsilon$ -delay schemes. The proposed schemes can order simultaneous events correctly in Time Warp-based distributed simulation of DEVS models.