• International Journal of Highway Engineering
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• v.6 no.3 s.21
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• pp.37-46
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• 2004

This study was performed to establish valid methodology for determining dynamic stability(DS) of deformation-cycle curve which is obtained through wheel tracking(WT) test, the most widely used method for forecast of rutting tendency of asphalt mixture. Existing Korean and Japanese methods for DS are unrealistic and do not really reflect characteristics of rut resistance of asphalt concretes especially when the slope of deformation-cycle curve is stabilized at the end. It was proved that the new DS developed in this study reflected rut resistance characteristics better than existing methods. It is especially effective to distinguish the mixtures with high DR(depth of rut) but stable slope at the end of curve from the mixture with lower DR and continuous slope. The field evaluation must be followed to prove whether the mixture which shows a high DS value this method perform well in the filed.

• International Journal of Highway Engineering
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• v.8 no.1 s.27
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• pp.77-87
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• 2006

Dynamic stability (DS) in the wheel tracking (WT) test is used as a basic index of rut-resistance for asphalt mixtures. In general, the deeper rut depth is obtained from the weaker mixture, resulting in the lower DS value. On the other hand, the shallower rut depth is obtained from the stronger mixture, resulting in the higher DS. However, it is not always the case when the DS is calculated by the existing method because the DS is simply determined based on the slope at the final stage of the rut depth-cycle curve. Specifically, in the case of the depth-cycle curve showing a steeper slope in the early part but flatter slope in last part, the DS is calculated to be higher than the curve showing a ever-increasing slope throughout the test. As long as the last part of slope is flatter, the deeper final rut depth is evaluated to show a higher DS than the little final rut depth. Therefore, a reasonable method for DS evaluation need to be established. Several new methods were suggested by considering the early, middle and final parts of rut depth to determine a reasonable DS. The results have shown that those new methods have demonstrated a significant improvement in distinguishing similarly performing mixtures. The result also showed that $DS_2$ had better correlation with SD than any other methods , representing the rutting resistance of asphalt mixture very well. The new DS calculation method is relatively simple and easy to follow. More validatin study is required for practical application.

• Journal of The Korean Society of Integrative Medicine
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• v.10 no.3
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• pp.63-72
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• 2022

Purpose : Several studies have investigated the effects of dynamic stretching (DS) and self-mobilization (SM), however, studies comparing the two interventions are rare. Therefore, the purpose of this study was to compare the effects of DS and SM on ankle strength, dorsiflexion range of motion (DFROM), and balance to determine which is superior. Methods : Thirty-two healthy young adults participated in this study. Participants were randomly assigned to two groups (SM and DS). DS was performed for the purpose of stretching the medial gastrocnemius muscle. For the SM group, ankle joint SM was performed in three ways. For all participants, the following measurements were performed as pre- and post-tests: isometric strength of dorsiflexor and plantar flexor, weight-bearing lunge test (WBLT) to evaluate DFROM, Tetrax system to evaluate static balance, and y balance test (YBT) to evaluate dynamic balance. Differences before and after the intervention within each group were compared using paired t-test. Also, the variable's variation was compared between groups using an independent t-test. Results : Significant differences were found in ankle dorsiflexor strength, WBLT, YBT, weight distribution index (WDI) (pillow and opened eyes; PO), and stability index (ST) (normal and closed eyes; NC) before and after intervention in the SM group (p<.05). In the DS group, significant differences were found in ankle dorsiflexor and plantar flexor strength, WBLT, YBT anterior, WDI (normal and opened eyes; NO, PO), and ST (NO, NC, PO, pillow and closed eyes) before and after the intervention (p<.05). Ankle plantar flexor strength and WDI (PO) were significantly different between groups. Conclusion : Based on the results of this study, DS or SM can be considered as a possibility for selective use according to variables for improving ankle joint function (DFROM, muscle strength, balance).

• The Journal of Korean Physical Therapy
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• v.33 no.6
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• pp.286-291
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• 2021

Purpose: This study aims to measure the improvement of balanced ability and rapid response of 30 healthy adults by performing dynamic stretching, static stretching, and sargent jump. Methods: The sample 30 peoples without any musculoskeletal disease who volunteered to be the subject of the study. We measured all subjects on following metrics to evaluate the function and stability under the normal condition, with dynamic stretching (DS) group, static stretching (SS) group: vertical jump height and reaching distance Anterior, Posteromedial, Posterolateral and NO (Normal eye open), NC (Normal eye close), PO (Pillow with eye open), and PC (Pillow with close eye) were evaluated. All measures were analyzed using independent t-test and One-way repeated Anova. Results: There was a significant increase in SJH (Sargent jump) in both groups (p<0.05). In Y-balance test, there was a significant increase in both groups except for the ANT (Anterior) direction, and there was a significant increase only in the SS group in the ANT (Anterior) direction (p<0.05). There was no significant difference between the DS group and the SS group (p>0.05). There was no significant improvement in ST (Stability Index) and WDI (Weight Distribution Index) in both groups (p>0.05). Conclusion: Both DS and SS showed significant improvement in SJH and Y-balance tests, which are dynamic functions, but had no significant effect on static balance ability.

• International Journal of Highway Engineering
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• v.7 no.4 s.26
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• pp.91-102
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• 2005

This study dealt with correlation analysis of binder stiffness with deformation strength and dynamic creep property of asphalt mixtures for evaluation of applicability of deformation strength $(S_D)$. Two aggregates, with maximum size of 13mm and eight binders were used to produce 16 different mixtures. The stiffness of binder $(G^*/sin\delta)$ was measured using DSR at $64^{\circ}C$. Final deformation(FD) and dynamic stability(DS) were measured by dynamic creep (DC) test, and SD was measured by Kim test for each mixture. Results of correlation analysis between $G^*/sin\delta$, and $S_D$, m and DS showed that correlation with binder stiffness and deformation strength was the highest $(R^2>0.88)$. There was good correlation between DS, FD with $S_D$. The results indicated that rut-resistance property of mixture is better reflected in $S_D$ test than FD or DS of dynamic creep test. Therefore, it is concluded that $S_D$ can be possibly used for evaluation of rut resistance of asphalt concretes with a good reliability if the procedure is standardized.

• Physical Therapy Rehabilitation Science
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• v.6 no.4
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• pp.182-188
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• 2017

Objective: The purpose of this study was to compare ankle function between adults with and without Down syndrome (DS). Design: Cross-sectional study. Methods: Ten adults with DS and 18 without participated in this study and underwent manual muscle test (MMT), range of motion (ROM) assessment, star excursion balance test (SEBT), and functional movement screen (FMS). The tests were demonstrated to increase their accuracy and the actual measurements were assessed after one or two demonstrations. To minimize the standby time and fatigue, the travelled distance and measuring order were adjusted. To remove the influence of shoes on the measurements, the shoes were taken off and only socks were worn. Results: Dorsal and plantar flexion MMTs of both ankles were significantly weaker and plantar flexion ROM of both ankles were significantly lower in adults with DS compared with those without (p<0.05). However, dorsal flexion ROM of both ankles were not significantly different between them. There were significant differences in distances measured in all the directions (anterior, anterolateral, lateral, posterolateral, posterior, posteromedial, medial, and anteromedial directions) of SEBT (p<0.05). Significant differences were also demonstrated in the scores of hurdle step, inline lunge, shoulder mobility, and rotary stability among the seven items of FMS (p<0.05). Conclusions: To enhance the dynamic stability of adults with DS, it is necessary to improve ankle stability by strengthening the ankle dorsal and plantar flexors.

• International Journal of Highway Engineering
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• v.6 no.4 s.22
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• pp.45-53
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• 2004

This study dealt with correlation analysis between deformation strength and rut resistance of asphalt concretes based on binder grade in Superpave specification with changing submerging time. Currently, Mashall mix design is known to have little correlation with rutting related performance. Therefore, some agencies started to use the Superpave method for asphalt mix design. But this method has a weak point in that it can not distinct mechanical property of the asphalt mixtures designed. For solution of these problem, this study used deformation strength, $S_D$, of Kim test which is a new approach under development for finding property which represents rut resistance characteristics of asphalt mixtures under static loading. This study used two aggregates from two regions and five PG asphalt binders. Final rut depth (DR) and dynamic stability (DS) from wheel tracking (WT) test were obtained. and $S_D$ value of the same mixture specimen which was made by gyratory compactor was obtained using loading head [4(1.0)]. Three submerging times 30min, 40min, 50min were used as a test variable at $60^{\circ}C$. Correlation analysis of DR and DS with $S_D$ were performed based on PG grade. It was found out that the $S_D$ has a high correlation with DR and DS of superpave mixtures. The highest $R^2$ was found from the $S_D$ values of 30min. submerged specimen.

• Journal of Electrical Engineering and Technology
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• v.12 no.4
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• pp.1456-1470
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• 2017

This paper presents sensorless vector control of induction motor drives with an improved model reference adaptive system observer for rotor speed estimation and parameters identification from measured stator currents, stator voltages and estimated rotor fluxes. The aim of the proposed sensorless control method is to compensate simultaneously stator resistance and rotor time constant variations which are subject of large changes during operation. PI controllers have been used in the model reference adaptive system adaptation mechanism and in the closed loops of speed and currents regulation. The stability of the proposed observer is proved by the Lyapunov's theorem and its feasibility is verified by experimentation. The experimental results are obtained with an 1 kW induction motor using Matlab/Simulink and a dSPACE system with DS1104 controller board showing the effectiveness of the proposed approach in terms of dynamic performance.

• The Transactions of the Korean Institute of Power Electronics
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• v.6 no.1
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• pp.98-106
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• 2001

This paper presents external load disturbance compensation that used to deadbeat load torque observer and regulation of the compensation gain by parameter estimator. As a result, the response of PMSM follows that of the nominal plant. The load torque compensation method is compose of a dead beat observer that is well-known method. However it has disadvantage such as a noise amplification effect. To reduce of the effect, the post-filter, which is implemented by MA process, is proposed. The parameter compensator with RLSM(recursive least square method) parameter estimator is suggested to increase the performance of the load torque observer and main controller. Although RLSM estimator is one of the most effective methods for online parameter identification, it is difficult to obtain unbiased result in this application. It is caused by disturbed dynamic model with external torque. The proposed RLSM estimator is combined with a high performance torque observer to resolve the problems. As a result, the proposed control system becomes a robust and precise system against the load torque and the parameter variation. A stability and usefulness, through the verified computer simulation and experiment, are shown in this paper.