• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.1
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• pp.291-304
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• 2019

This paper proposes a dynamic-tiling-based bandwidth-efficient (DTBE) virtual reality (VR) streaming scheme. We consider 360-degree VR contents with multiple view points such as the front, back, upper, and bottom sides. At a given time, the focus of a client is always bound to a certain view among multiple view points. By utilizing this perspective, under our proposed scheme, tiles with high encoding rates are selectively assigned to the focused view where multiple view points consist of multiple tiles with different encoding rates. The other tiles with low encoding rates are assigned to the remaining view points. Furthermore, for reducing view adaptation delay, we design a novel rapid view adaptation mechanism that selectively delivers an I-frame during view point updates by using frame indexing. We implement the proposed scheme on a commercial VR test bed where we adopt the MPEG media transport (MMT) standard with high-efficiency video coding (HEVC) tile modes. The measurement-based experiments show that the proposed scheme achieves an average data usage reduction of almost 65.2% as well as average view adaptation delay reduction of almost 57.7%.

• Journal of the Korean Society of Physical Medicine
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• v.14 no.1
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• pp.35-41
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• 2019

PURPOSE: This study examined the effects of a vestibular stimulation training program on the walking ability of chronic stroke patients over a six month period. METHODS: Forty stroke patients were enrolled in this study. The patients were divided randomly into a control group (n=20) and experimental group (n=20). A general exercise program was applied to Group I and vestibular stimulation training was applied to Group II(30 min, three times a week for six weeks). The changes in straight walking ability, curved walking ability, and functional walking ability were measured using a 10 m walking test figure-of-eight-walking test, and dynamic gait index, respectively. The measures before and after the program were compared using a paired t-test for a comparison of each group and an independent t-test for a comparison between groups. RESULTS: The changes in each group were examined according to the measurement period. The Experimental group showed significant functional improvement in all three tests after the vestibular stimulation training program, but the control group did not show significant improvement in any of the tests after the general exercise program. A comparison of the changes between groups revealed the experimental group to show significantly higher improvement than the control group in all tests. CONCLUSION: The vestibular stimulation training program helps improve the gait function of stroke patients. Based on the results of this study, it is expected that various vestibular stimulation training programs will be developed and applied in a range of places.

• Physical Therapy Rehabilitation Science
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• v.8 no.3
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• pp.141-145
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• 2019

Objective: The purpose of this study was to compare walking conditions (straight line and curved path) on walking patterns in persons who had experienced hemiplegic stroke and to determine whether if they adapt their walking pattern and performances according to changes in environmental conditions. Design: Cross-sectional study. Methods: Forty-four hemiplegic stroke survivors participated in this study. This study measured walking performance in three different walking conditions, such as straight walking, the more-affected leg in the inner curve walking, and less-affected leg in the inner curve walking conditions, and a 2-dimentional gait analysis system was used as a primary measurement. This study also measured secondary clinical factors including the Timed Up-and-Go Test, the Trunk Impairment Scale, and the Dynamic Gait Index. Results: After analyzing, cadence and step length of the less-affected side, stride length in the more-affected side, and stride length in less-affected side were significantly different among the three different walking conditions in this study (p<0.05), but other temporospatial parameters were not significant. Cadence was the largest in the straight walking condition. Step length in the less-affected side, stride length in the more-affected side, and stride length in less-affected side were also the longest in the straight walking condition. Conclusions: The results of the study suggest that hemiplegic stroke survivors show walking adaptability according to changes in walking demands and conditions, and moreover, cadence and step and stride lengths were significantly different between straight and curved walking conditions.

• KIPS Transactions on Software and Data Engineering
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• v.8 no.4
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• pp.153-162
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• 2019

Recently, it is necessary to develop a technology for quantitatively evaluating railway vibration to prevent civil complaints about orbital structures caused by railway noise and normal operation of ultra-precise equipment of orbital industrial complexes. The existing analytical method requires a very complicated dynamic response model, and it is difficult to secure the reliability of the result due to the inaccuracy of the demand model. Therefore, in this paper, we propose a railway vibration evaluation algorithm and system that deduce the vibration value generated from railway operation by using Linear Regression and Gradient Descent technique based on actual measurement railway vibration database that classifies factors affecting railway vibration. The prediction results obtained by the proposed algorithm show higher efficiency and accuracy than the existing analytical methods.

• Proceedings of the Korea Water Resources Association Conference
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• 2017.05a
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• pp.66-66
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• 2017

Hydraulic jump is typically designed to occur over low-haed dam spillways and weirs in the river. An important engineering application of the hydraulic jump is to dissipate the intense kinetic energy of the flows over such hydraulic structures. Turbulent flow and roller-like vortex riding up the free sureface of the jump cause most of the energy dissipation. We carry out a high resolution three-dimensional numerical simulations of a submerged hydraulic jump in a spillway and compare numerical results with a laboratory measurement obtained by the PIV. The numerical results further show the dynamic behavoirs of the inner and outer layers of the submerged wall-jet and the recirculating roller of the hydraulic jump.

• The Journal of Asian Finance, Economics and Business
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• v.8 no.1
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• pp.479-486
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• 2021

This study aims to explore the relationships between strategic planning, strategic maneuverability, and firm performance in the current dynamic business environment. It employs a quantitative research method and reports on a survey, using a questionnaire, of service companies in Indonesia's oil and gas industry. Of the 337 companies selected by simple random sampling from a vendor database, responses were received from 70 companies. The analysis was performed using Partial Least Square Structural Equation Modeling and SmartPLS software. The analysis consisted of descriptive statistics, evaluation of the measurement model, evaluation of the structural model, and hypotheses testing. The results show that both strategic planning and strategic maneuverability have a positive relationship with firm performance. In addition, there is a positive relationship between strategic planning and firm performance through the mediating role of strategic maneuverability. The findings suggest that the organizational agility, organizational flexibility, and organizational responsiveness that constitute strategic maneuverability have a positive direct and indirect effect on firm performance, namely financial performance, customer performance, internal process performance, and learning and growth. This study contributes to the strategic management literature and the theory of maneuvers by providing empirical evidence on the relationship between strategic planning, strategic maneuverability, and firm performance.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.19 no.12
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• pp.34-41
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• 2020

Ready-mixed concrete is unconsolidated concrete typically transported to construction sites by using mixer trucks. A proper rotation of concrete is necessary to prevent its solidification in mixer trucks during transport: in accordance with the manufacturing method and quality inspection prescribed in KSF4009, this movement is maintained after the manufacturing of concrete in professional production plants and the addition of water, solid materials, and admixtures. Unfortunately, mixer truck parts wear out over long periods of time. In order to improve the wear resistance of the main part of mixer trucks, we used a steel plate with good wear resistance or partially added a reinforcement plate. In this study, we first tested the properties of concrete (as required for the DEM), and then carried out mixing and discharge simulations to define the actual operating conditions of mixer trucks. For each condition, we calculated the amount and location of wear. The reliability of our results was finally verified by comparing them with the measurement values. Overall, this study provided basic data for an optimal design of mixer trucks: one that would reduce the vehicles' weight and production costs.

• The Journal of Asian Finance, Economics and Business
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• v.8 no.7
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• pp.603-611
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• 2021

This study aims to analyze the mediating influences of resonance-based self-attitude and brand credibility in a relationship between celebrity endorser credibility and celebrity endorser congruity toward brand purchase intention in the current dynamic business environment. It employs a quantitative research method and reports on a survey, using a questionnaire, including the population of consumers of various instant coffee brands in several cities in Indonesia. The number of respondents in this study was 432 people. The analysis was performed using Partial Least Square Structural Equation Modeling and SmartPLS software. The analysis consisted of descriptive statistics, evaluation of the measurement model, evaluation of the structural model, and hypothesis testing. The results partially support the model developed. The findings suggest that the instant coffee product advertising in Indonesia needs to create brand messages focusing on the formation of resonance-based self-attitude from consumers to increase the influence of celebrity endorser credibility and celebrity endorser congruity, as well as the brand credibility towards the brand purchase intention. This study contributes to the marketing literature and the theory of planned behavior by providing empirical evidence on the relationship between celebrity endorser credibility, celebrity endorser congruity, resonance-based self-attitude, brand credibility, and brand purchase intention.

• PNF and Movement
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• v.10 no.2
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• pp.1-8
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• 2012

Purpose : The purpose of study was aimed to identify whether the painless dynamic PNF techniques makes any differences in reducing lymphedema by applying this technique to lymphedema patients, and to provide the basic reference data for the purpose of applying to lymphedema patients. Methods : A total of 40 women participated in this study, and they did PNF techniques before applying lymph compression bandages. Group 1 of 20 subjects performed PNF techniques three times a week with 30 minutes each time. Group 2 of 20 subjects only practiced edema reducing massaging for 30 minutes. Results : In addition, the interaction between treatment method and treatment time was significant (p<.0001), which indicates that the changes in edema rates by measurement times appear differently according to treatment methods. In this study, it means that the 'PNF techniques' group has a steeper slope of decline than the 'message' group. Conclusion : In conclusion, both massaging and PNF techniques helped to lower edema rates. Four weeks after the beginning of treatment, PNF techniques was exhibited as generating a large degree of decline in edema rates than massaging.

• Mass Spectrometry Letters
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• v.12 no.2
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• pp.47-52
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• 2021

Evaluating the impurity concentrations in semiconductor thin films using time of flight secondary ion mass spectrometry (ToF-SIMS) is an effective technique. The mass interference between isotopes and matrix element in data interpretation makes the process complex. In this study, we have investigated the doping concentration of phosphorus in, phosphorus doped silicon thin film on glass using ToF-SIMS in the dynamic mode of operation. To overcome the mass interference between phosphorus and silicon isotopes, the quantitative analysis of counts to concentration conversion was done following two routes, standard relative sensitivity factor (RSF) and SIMetric software estimation. Phosphorus doped silicon thin film of 180 nm was grown on glass substrate using hot wire chemical vapor deposition technique for possible applications in optoelectronic devices. Using ToF-SIMS, the phosphorus-31 isotopes were detected in the range of 10¹~10⁴ counts. The silicon isotopes matrix element was measured from p-type silicon wafer from a separate measurement to avoid mass interference. For the both procedures, the phosphorus concentration versus depth profiles were plotted which agree with a percent difference of about 3% at 100 nm depth. The concentration of phosphorus in silicon was determined in the range of 10¹⁹~10²¹ atoms/cm³. The technique will be useful for estimating distributions of various dopants in the silicon thin film grown on glass using ToF-SIMS overcoming the mass interference between isotopes.