• The Journal of Korean Institute of Communications and Information Sciences
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• v.39B no.6
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• pp.414-423
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• 2014

The number and size of resource constituting the web page has been increasing steadily, and this circumstance leads to rapidly falling quality of web service in mobile network that offer relatively higher delay. Moreover, Improving the quality of a web services protocol is difficult to provide network function because the current network architecture has closed structure. In this paper, we suggest schemes to enhance web performance in mobile network, which are Check Coded DOM scheme and Functional JavaScript Transmission scheme, and then try to seek idea which can be provided suggested schemes as a network function using NFV(Network Function Virtualization). For the performance evaluation and analysis about the suggested schemes, we perform network simulation using SMPL library. We confirm that suggested schemes offer better performance in term of page loading time, the number of message and the amount of traffic in the network than HTTP Protocol.

• Journal of The Korean Society of Integrative Medicine
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• v.8 no.2
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• pp.89-95
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• 2020

Purpose : This study aims to evaluate the correlation of cognitive function, activities of daily living (ADL), and driving performance in stroke hemiplegic patients residing in Korea. Methods : Subjects of the study were 18 stroke hemiplegic patients admitted to hospitals situated in Seoul. A clock drawing test (CDT), a modified Barthel index (MBI), and a virtual reality driving simulator (Eca faros-driving simulator) were used to examine their cognitive function, their ADL ability, and their driving skills, respectively. Results : Driving skills of stroke hemiplegic patients were shown to be associated with the CDT evaluation tool (r=-.777) (p<.001), but they were found to have any correlation with MBI (r=-.022) (p>.05). Additionally, an individual's CDT showed that the driving simulator evaluation result (pass/fail) could be discriminated with a sensitivity of 100.0 %, a specificity of 40.0 %, and an accuracy of 66.7 %. The result confirmed that the CDT is a useful evaluation tool for screening driving ability in people with stroke. But the MBI did not show any significant results (sensitivity of 62.5 %, specificity of 40.0 %, and predicted the results of the simulator with 50.0 % of accuracy) (p>.05). Conclusion : This study shows that cognitive function influences the driving performance in people with stroke. Driving skills of stroke hemiplegic patients are seen to be highly related to CDT. In the field of driving rehabilitation, these findings could be useful for evaluating driving skills relating to CDT. Furthermore, the study results will set a guideline for domestic occupational therapists to use the evaluation tool for assessing driving abilities in people with stroke.

• Journal of the Korean Society of Hazard Mitigation
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• v.9 no.5
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• pp.93-102
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• 2009

A prediction of streamflow based on multi-objective function is presented to check the performance of Probability Distributed Model(PDM) in Miho stream basin, Chungcheongbuk-do, Korea. PDM is a lumped conceptual rainfall runoff model which has been widely used for flood prevention activities in UK Environmental Agency. The Monte Carlo Analysis Toolkit(MCAT) is a numerical analysis tools based on population sampling, which allows evaluation of performance, identifiability, regional sensitivity and etc. PDM is calibrated for five model parameters by using MCAT. The results show that the performance of model parameters(cmax and k(q)) indicates high identifiability and the others obtain equifinality. In addition, the multi-objective function is applied to PDM for seeking suitable model parameters. The solution of the multi-objective function consists of the Pareto solution accounting to various trade-offs between the different objective functions considering properties of hydrograph. The result indicated the performance of model and simulated hydrograph are acceptable in terms on Nash Sutcliffe Effciency*(=0.035), FSB(=0.161), and FDBH(=0.809) to calibration periods, validation periods as well.

• International Journal of Reliability and Applications
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• v.6 no.2
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• pp.87-99
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• 2005

Coverage-based software reliability growth models (SRGMs) have been developed and successfully applied in practice. Performance of a coverage-based SRG M depends on the coverage function employed by the SRGM. When the coverage function represents the coverage growth behavior well irrespective of type of the testing profile the corresponding coverage-based SRGM is expected to be widely applicable. This paper first conducts a study of selecting the most representative coverage functions among the available coverage functions. Then their performances are empirically evaluated and compared. The result provides a foundation for developing widely applicable coverage-based SRGMs and monitoring the progress of a testing process.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.54 no.1
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• pp.17-25
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• 2005

This paper provides sufficient conditions for the robustness of Affine linear TFM(Transfer Function Matrix) MIMO (Multi-Input Multi-Output) uncertain systems based on Rosenbrock's DNA (Direct Nyquist Array). The parametric uncertainty is modeled through a Affine TFM MIMO description, and the unstructured uncertainty through a bounded perturbation of Affine polynomials. Gershgorin's theorem and concepts of diagonal dominance and GB(Gershgorin Bands) are extended to include model uncertainty. For this type of parametric robust performance we show robustness of the Affine TFM systems using Nyquist diagram and GB, DNA(Direct Nyquist Array). Multiloop PI/PB controllers can be tuned by using a modified version of the Ziegler-Nickels (ZN) relations. Simulation examples show the performance and efficiency of the proposed multiloop design method.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.6
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• pp.1223-1229
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• 2009

The performance of Radial Basis Function Neural Networks depends on setting up the Radial Basis Functions over the input space which are the important design procedure of Radial Basis Function Neural Networks. The existing method to initialize the location of the radial basis functions over the input space is to use the conditional fuzzy C-means clustering. However, the researchers which are interested in the conditional fuzzy C-means clustering cannot get as good modeling performance as they expect because the conditional fuzzy C-means clustering cannot project the information which is extracted over the output space into the input space. To compensate the above mentioned drawback of the conditional fuzzy C-means clustering, we apply a fuzzy K-nearest neighbors approach to project the auxiliary information defined over the output space into the input space without lose of the information.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.11
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• pp.6810-6814
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• 2014

The concept of IFS (Iterated Function System) was applied to compress and transmit image data efficiently. To compress the image data with IFS, self-similarity was used to search a similar block. To improve the coding performance for the iterated function system with natural images, the image will be formed of properly transformed parts of itself to minimize the coding error. The simulation results using the proposed IFS represent high PSNR performance and improved compression efficiency with the coefficient of a recursive function.

• Structural Engineering and Mechanics
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• v.67 no.4
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• pp.327-336
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• 2018

In this study, an efficient damage index is proposed to identify multiple damage cases in structural systems using the concepts of frequency response function (FRF) matrix and strain energy of a structure. The index is defined based on the change of strain energy of an element due to damage. For obtaining the strain energy stored in elements, the columnar coefficients of the FRF matrix is used. The new indicator is named here as frequency response function strain energy based index (FRFSEBI). In order to assess the performance of the proposed index for structural damage detection, some benchmark structures having a number of damage scenarios are considered. Numerical results demonstrate that the proposed index even with considering noise can accurately identify the actual location and approximate severity of the damage. In order to demonstrate the high efficiency of the proposed damage index, its performance is also compared with that of the flexibility strain energy based index (FSEBI) provided in the literature.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.37 no.2
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• pp.8-15
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• 2000

This study presents an H$_{\infty}$ optimal controller synthesis by the frequency domain analysis of weighting function. The main purpose of our study is to visualize weighting function domains and open loop transfer function domains that satisfy robustness and performance. Also we aim to simplify the iterative algorithm for H$\infty$ optimal controller synthesis. We report that the designed regulator by the proposed method in this paper satisfies the desired specifications and performance in spite of the plant uncertainty variation at any operating point.

• Proceedings of the KIEE Conference
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• 2007.04a
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• pp.119-121
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• 2007

PID control is windely used to control stable processes, however, its application to integrating processes is less common. In this paper, we proposed a simple PID controller tuning method for integrating processes with time delay to meet a sensitive function $M_s$. With the proposed PID tuning method, we can obtain stable integrating processes using PD controller in inner feedback loop and a loop transfer function with desired stable specification. This guarantees both robustness and performance. Simulation examples are given to show the good performance of the proposed tuning method to other methods.