• The Journal of the Korea Contents Association
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• v.18 no.11
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• pp.348-352
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• 2018

BioRescue ($RMIng{\acute{e}}nierie$, Marseille, France) is able to assess dynamic and static balance when a test subject stands or sits over the platform. Although previous studies have examined the reliability of other balance measurement methods, little research has been conducted on the reliability of equipment such as BioRescue. This study examined the intra-rater and inter-rater reliability of BioRescue during balance assessment. Thirty-four healthy adults participated as subjects and two physical therapists participated as examiners to determine intra- and inter-rater reliability. BioRescue was used to conduct measurements during footprint (area and pressure), Romberg, and limit of stability tests. The footprint area and limit of stability tests yielded intra- and inter-rater reliability ICC values above 0.60 in all directions. However, the footprint pressure and Romberg tests yielded values below 0.60 in all directions. BioRescue showed good inter-rater and intra-rater reliability in measurements during footprint area and limit of stability tests. However, because the values of limits of stability show the difference between experienced and unskilled, skill is required for the accuracy of the equipment.

• Explosives and Blasting
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• v.37 no.1
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• pp.1-13
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• 2019

The repeated blasting vibration, which is induced commonly in NATM excavation site, can cause a severe damage to the nearby facilities. It is known that the most effective method for reducing blasting vibration includes the use of electronic detonator, deck charge and change of cut method, and so forth. In order to analyze the effect of blasting vibration reduction, in this study, three-dimensional FDM (Finite Difference Method) program FLAC3D has been used for reflecting the blasting hole, delayed time and charging amount. Also the numerical analysis has been performed by applying a dynamic load to each blasting hole. The cut method has been applied with several methods, such as V-cut and Double-drilled parallel cut, which are common in tunnel construction sites. Also, the field test blasting has been carried out in order to compare the measured data with results of numerical analysis. It was shown that the numerical analysis and the field measurement coincide well.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.39 no.1
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• pp.147-154
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• 2019

The finite element model updating can be defined as the problem of finding the parameters of the finite element model which gives the closest response to the actual response of the structure by measurement. In the previous researches, optimization based methods have been developed to minimize the error of the response of the actual structure and the analytical model. In this study, we propose an inverse eigenvalue problem that can directly obtain the parameters of the finite element model from the target mode information. Deep Neural Networks are constructed to solve the inverse eigenvalue problem quickly and accurately. As an application example of the developed method, the dynamic finite element model update of a suspension bridge is presented in which the deep neural network simulating the inverse eigenvalue function is utilized. The analysis results show that the proposed method can find the finite element model parameters corresponding to the target modes with very high accuracy.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.10a
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• pp.527-530
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• 2014

DASH is a well-known streaming technology, which was proposed in 2010 by MPEG and standardized in 2011. Major multimedia contents service providers, including Apple, Microsoft, and Adobe are all using this technology to support their media streaming services. Whenever a new service is requested to the server, the DASH technology helps servicing the multimedia streaming to client by recognizing the capacity of network and by adapting the quality of the multimedia contents. In DASH, the quality of multimedia contents will be automatically lowered to meet the fluctuating network status, when undesirable breaks interrupt the network. In this paper, we classified and analysed the advantages and disadvantages of DASH researches in three aspects: bit-rate measurement method, bandwidth aggregation method; rate adaptation metrics, algorithms and logics; user's experiences and QoE.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.49 no.4
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• pp.311-320
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• 2021

A study is performed for the real time fault diagnosis during operation and health estimation relating to performance deterioration in a turbojet engine used for an unmanned air vehicle. For this study the real time dynamic model is derived from the transient thermodynamic gas path analysis. For real fault conditions which are manipulated for the simulation, the detection techniques are applied such as Kalman filter and probabilistic decision-making approach based on statistical hypothesis test. Thereby the effectiveness is verified by showing good fault detection and isolation performances. For the health estimation with measurement parameters, it shows using an assumed performance degradation that the method by adaptive Kalman filter is feasible in practice for a condition based diagnosis and maintenance.

• PNF and Movement
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• v.19 no.2
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• pp.269-278
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• 2021

Purpose: This study aimed to investigate effective cueing methods for selective muscle activation of the serratus anterior. Methods: Based on the inclusion criteria, 26 healthy adults, both males and females, were recruited for the measurement of muscle activation of the upper trapezius and serratus anterior muscles while performing basic movements in knee push-up plus (KPP) and dynamic hug (DH) positions using five different cueing methods. An electromyogram was used to measure muscle activation, and both muscle activation and muscle ratio (serratus anterior/upper trapezius) were compared during the basic movements and different cueing methods. The cueing methods were trapezius verbal cueing, trapezius verbal cueing + trapezius tactile cueing, emphasis verbal cueing, serratus anterior tactile cueing, and trapezius verbal cueing + trapezius tactile cueing + serratus anterior tactile cueing. Results: The results of the study showed that there was a significant difference in the muscles for the two exercises (p < 0.05). There was also a significant difference between the cueing methods (p < 0.05). The correlative effect between the muscles and cueing methods was also significant (p < 0.05). The muscle ratio in trapezius verbal cueing + trapezius tactile cueing + serratus anterior tactile cueing during KPP and DH was higher than in basic movements and other cueing methods. This confirms that trapezius verbal cueing + trapezius tactile cueing + serratus anterior tactile cueing is an effective cueing method for selective activation of the serratus anterior during KPP and DH. This study also demonstrated that cueing by a therapist may both increase and decrease selective muscle activation. Conclusion: Through this study, an effective cueing method to selectively activate the serratus anterior may be suggested, and the results of this study may provide basic information regarding future studies and clinical practice.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.34 no.4
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• pp.221-230
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• 2021

This paper proposes full waveform inversion (FWI) for estimating the physical properties of a layered half-space. An FWI solution is obtained using a genetic algorithm (GA), which is a well-known global optimization approach. The dynamic responses of a layered half-space subjected to a harmonic vertical disk load are measured and compared with those calculated using the estimated physical properties. The responses are calculated using the thin-layer method, which is accurate and efficient for layered media. Subsequently, a numerical model is constructed for a layered half-space using mid-point integrated finite elements and perfectly matched discrete layers. An objective function of the global optimization problem is defined as the L2-norm of the difference between the observed and estimated responses. A GA is used to minimize the objective function and obtain a solution for the FWI. The accuracy of the proposed approach is applied to various problems involving layered half-spaces. The results verify that the proposed FWI based on a GA is suitable for estimating the material properties of a layered half-space, even when the measured responses include measurement noise.

• Journal of the Korean Society of Physical Medicine
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• v.16 no.4
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• pp.13-21
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• 2021

PURPOSE: This study examined the effects of action observational training with acoustic stimulation (AOTA) on the balance and gait ability in stroke patients. METHODS: Forty-five chronic stroke patients were divided into three groups. The AOTA group (n = 15) received training via a video that showed a normal gait with the sound of footsteps. The action observation training (AOT) group (n = 15) received AOT without acoustic stimulation. The control group (n = 15) received physical training. Each intervention was applied once per day, three times per week for six weeks. The participants in the AOTA and AOT groups had five minutes of AOT. The participants in the all group had 20 minutes of physical training. All participants were measured using the Berg Balance Scale, the Timed Up and Go Test, the Functional Reaching Test, 10 Meter Walk Test, six Minute Walk Test, and Dynamic Gait Index. The collected data were analyzed using SPSS version 20.0 for Windows. The between- and within-group comparisons were analyzed using the one-way analysis of variance (ANOVA) test and a paired t-test, respectively. For all statistical analyses, the significance level was set to .05. RESULTS: The one-way ANOVA test identified significant differences among the measurement results of the three groups (p < .05). Post hoc analyses indicated the AOTA group to undergo more significant balance and gait changes than the control group (p < .05). CONCLUSION: The gait and balance abilities could be improved effectively for patients with stroke when action observation training and acoustic stimulation were applied simultaneously.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.32 no.6
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• pp.1069-1080
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• 2022

Zero trust, which means never trust anything before verifying it, is emerging as a hot issue in security field. After authenticating users, zero trust establishes network boundaries so that only networks in the trusted range can be accessed. This concept is also consistent with the concept of SDP, which performs pre-verification and creates a network boundary with a dynamic firewall so that clients can access only as many as they have permission to connect. Therefore, we recommend the SDP model as an example of how zero trust can be achieved in a zero trust architecture. In this paper, we point out the areas where SDP needs to be modified for zero trust and suggest ways to overcome them. In addition, we propose an onboarding method, which is one of the processes for becoming an SDP entity, and present performance measurement results.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.17 no.2
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• pp.391-411
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• 2023

Aggregates play the skeleton and supporting role in the construction field, high-precision measurement and high-efficiency analysis of aggregates are frequently employed to evaluate the project quality. Aiming at the unbalanced operation time and segmentation accuracy for multi-class segmentation algorithms of aggregate images, a Chaotic Sparrow Search Algorithm (CSSA) is put forward to optimize it. In this algorithm, the chaotic map is combined with the sinusoidal dynamic weight and the elite mutation strategies; and it is firstly proposed to promote the SSA's optimization accuracy and stability without reducing the SSA's speed. The CSSA is utilized to optimize the popular multi-class segmentation algorithm-Multiple Entropy Thresholding (MET). By taking three METs as objective functions, i.e., Kapur Entropy, Minimum-cross Entropy and Renyi Entropy, the CSSA is implemented to quickly and automatically calculate the extreme value of the function and get the corresponding correct thresholds. The image adaptive multi-class segmentation model is called CSSA-MET. In order to comprehensively evaluate it, a new parameter I based on the segmentation accuracy and processing speed is constructed. The results reveal that the CSSA outperforms the other seven methods of optimization performance, as well as the quality evaluation of aggregate images segmented by the CSSA-MET, and the speed and accuracy are balanced. In particular, the highest I value can be obtained when the CSSA is applied to optimize the Renyi Entropy, which indicates that this combination is more suitable for segmenting the aggregate images.