• Structural Engineering and Mechanics
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• 제3권4호
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• pp.391-410
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• 1995

The application of adaptive finite element method to dynamic problems is investigated. Both the kinetic and strain energy errors induced by space and time discretization were estimated in a consistent manner and controlled by the simultaneous use of the adaptive mesh generation and the automatic time stepping. Also an optimal ratio of spatial discretization error to temporal discretization error was discussed. In this study it was found that the best performance can be obtained when the specified spatial and temporal discretization errors have the same value. Numerical examples are carried out to verify the performance of the procedure.

• 대한물리치료과학회지
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• 제8권2호
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• pp.977-987
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• 2001

The purpose of this study was to examine the effects of sensory integration therapy (SIT) on sensory' motor development and adaptive behavior of cerebral palsy children. The design of this study was quasi experiments with a non-equivalent pre- and post-test control design. Subjects of the study were arbitrarily chosen based on predetermined selection criteria among the cerebral palsy children who were treated as out-patients at two rehabilitation hospitals one in Seoul, and the other in Kyunggi-do. The study was conducted between early April and late July in 2000. Fifteen children were in the experimental group and eleven in the control group. The allocation was done based on ease of experimental treatment. A five-step SIT program was devised from a combination of SIT programs suggested by Ayres(1985) and Finks(1989), and an author-designed SIT program for cerebral palsy children. The experimental group was subjected to 20 to 30 minutes of SIT per session. two sessions a week for ten -week period. The effects of SIT were measured with respect to 9 sub-areas that can be administered to cerebral palsy children out of a total of 17 sub-areas in the Southern California Sensory Integration Test (SCSIT) developed by Ayres (1980). In addition. the scale developed by Russell (1993) for Gross Motor Function Measure (GMFM). and Perception Motor Development Test developed by 中司利一 et al.(1987) were also applied. Adaptive behavior was analyzed using guidelines in two unpublished documents - School-Age Checklist for Occupational Therapy by the Wakefield Occupational Therapy Associates, and the OTA-Watertown Clinical Assessment by the Watertown Occupational Therapy Associates-, and an author-developed Adaptive Behavior Checklist. Collected data were statistically analyzed by SPSS PC for chi square test, Mann-Whitney test, Wilcoxon signed rank test, and paired t-test. The results were as follows: 1. In sensory development, the experimental group exhibited a score increase compared to the control group, but the difference was not statistically significant, Although the experimental group showed improvements in all. 9 sub-areas compared to the control group, only right-left discrimination exhibited statistically significant change. 2. In gross motor development, the experimental group showed improvements in score compared to the control group, but it was not statistically significant. In fine motor development, the experimental group exhibited statistically significant improvements compared to the control group. In sub-area analysis, figure synthesis showed positive change. 3. In adaptive behavior development, post-experimental adaptive behavior scores were higher compared to pre-experimental scores with statistical significance. Furthermore, sub-areas emotional behavior, perception behavior, gross-fine motor function, oral-respiration function, motor behavior, motor planning, and adaptive response exhibited higher scores after SIT. In conclusion SIT was found to be partially effective in sensory and fine motor development, effective in all adaptive behavior areas, and not effective in gross motor development. Thus, this study has shown that SIT is an effective intervention for sensory development, fine motor development, and adaptive behavior for cerebral palsy children. But, for the effectiveness of SIT on gross motor development, further studies employing longer-time experiments are recommended.

• 대한교통학회지
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• 제14권2호
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• pp.89-118
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• 1996

The development and implementation of a real-time, traffic adaptive control scheme based on fuzzy logic through Video Image Detector systems (VIDs) is presented. Through VIDs based image processing, fuzzy logic can be used for a real-time traffic adaptive signal control scheme. Fuzzy control logic allows linguistic and inexact traffic data to be manipulated as a useful tool in designing signal timing plans. The fuzzy logic has the ability to comprehend linguistic instructions and to generate control strategy based on a priori verbal communication. The implementation of fuzzy logic controller for a traffic network is introduced. Comparisons are made between implementations of the fuzzy logic controller and the actuated controller in an isolated intersection. The results obtained from the application of the fuzzy logic controller are also compared with those corresponding to a pretimed controller for the coordinated intersections. Simulation results from the comparisons indicate the performance of the system is between under the fuzzy logic controller. Integration of the aforementioned schemes into and ATMS framework will lead to real-time adjustment of the traffic control signals, resulting in significant reduction in traffic congestion.

• 전산구조공학
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• 제8권3호
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• pp.5-10
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• 1995

공학분야에서 흔히 접하게 되는 접촉충격 문제들의 해석을 위해 접촉충격의 지배방정식과 효율적인 해석방법인 pinball contact-impact 알고리즘에 대해 기술하였다. 예제로 보여준 충돌하는 두 구조계의 접촉충격 해석과 자동차의 crashworthiness 해석결과들은 전술한 알고리즘이 매우 효율적임을 입증하고 있다. 자동차의 crashworthiness 해석과 같이 해석대상 모델이 크고 복잡한 경우에는 짧은 경과시간 동안의 거동변화를 파악하고자 하더라도 엄청난 계산시간이 소요된다. 따라서 효율적인 crashworthiness 해석을 위해서는 전술한 접촉충격 알고리즘 외에도, 논외의 대상이라 본문에서 소개하지는 않았으나, 강력한 요소(one-point integration element), 효과적인 비선형 동적해석 알고리즘, 해의 정확도를 높일 수 있는 adaptive method, 효율적인 시간적분을 위한 mixed time integration method(subcycling)와 explicit method 등을 복합적으로 혼합하여 사용하여야 한다.

• 한국전산유체공학회지
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• 제13권3호
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• pp.69-78
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• 2008

The high-order numerical method based on the adaptive mesh refinement(AMR) on the quadrilateral unstructured grids has been developed in this paper. This adaptive-grid method, originally developed with MUSCL-TVD scheme, is now extended to the WENO (weighted essentially no-oscillatory) scheme with the Runge-Kutta time integration of fifth order in spatial and temporal accuracy. The multidimensional interpolation was studied in the preliminary research, which allows us to maintain the same order of accuracy for the computation of numerical flux between two adjacent cells of different levels. Some standard benchmark tests are done to validate this method for checking the overall capacity and efficiency of the present adaptive-grid technique.

• Journal of Communications and Networks
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• 제17권4호
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• pp.428-439
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• 2015

In this study, we present an approach for reducing the information inaccuracy of existing star aggregation based on bypass links when there are multi-constraint QoS parameters in asymmetric networks. In our approach, bypass links with low similarity are selected. Links that are not chosen as bypass links are included in each group depending on the star's link characteristics. Moreover, each link group is aggregated differently according to the similarity of the links that make up the group. The selection of a bypass link by using link similarity reduces the existing time complexity of O($N^3$) to O(N) by virtue of the simplification of the selection process. In addition, the adaptive integration according to the characteristics of the links in each group is designed to reduce the information inaccuracy caused by static aggregation. Simulation results show that the proposed method maintains low information distortion; specifically, it is 3.8 times lower than that of the existing method, even when the number of nodes in a network increases.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• 제17권4호
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• pp.279-294
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• 2013

We are interested in an adaptive grid method for hyperbolic equations. A multiresolution analysis, based on a biorthogonal family of interpolating scaling functions and lifted interpolating wavelets, is used to dynamically adapt grid points according to the physical field profile in each time step. Traditional finite-difference schemes with fixed stencils produce high oscillations around sharp discontinuities. In this paper, we hybridize high-resolution schemes, which are suitable for capturing singularities, and apply a finite-difference approach to the scaling functions at non-singular points. We use a total variation diminishing Runge-Kutta method for the time integration. The computational cost is proportional to the number of points present after compression. We provide several numerical examples to verify our approach.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 학술대회 논문집 정보 및 제어부문
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• pp.421-424
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• 2008

The real time modeling of dynamic system on adaptive control system is very important for flying control system(FCS). Using traditional method, it is required much calculation load for integral/differential at control system. Therefore, It is very important theme of study in these days to find algorithms for integration/differential at FCS. These algorithms for integral/differential influence strongly stability/reliability to control flying object. In this paper, we present optimal predictive sampling time for reduce calculation load at FCS and optimal predictive time on general cost function by applying adaptive control method.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제15권4호
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• pp.1193-1215
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• 2021

The measurement of the key product quality index plays an important role in improving the production efficiency and ensuring the safety of the enterprise. Since the actual working conditions and parameters will inevitably change to some extent with time, such as drift of working point, wear of equipment and temperature change, etc., these will lead to the degradation of the quality variable prediction model. To deal with this problem, the selective integrated moving windows based principal component regression (SIMV-PCR) is proposed in this study. In the algorithm of traditional moving window, only the latest local process information is used, and the global process information will not be enough. In order to make full use of the process information contained in the past windows, a set of local models with differences are selected through hypothesis testing theory. The significance levels of both T - test and χ² - test are used to judge whether there is identity between two local models. Then the models are integrated by Bayesian quality estimation to improve the accuracy of quality variable prediction. The effectiveness of the proposed adaptive soft measurement method is verified by a numerical example and a practical industrial process.

• 한국군사과학기술학회지
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• 제1권1호
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• pp.201-210
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• 1998

Inertial Navigation System(INS) can provide the vehicle position and velocity information using inertial sensor outputs without the use of external aids. Unfortunately INS navigation error increases with time due to inertial sensor errors, and therefore it is desirable to combine INS with external aids such as GPS, TACAN, OMEGA, and etc.. In this paper we propose an integration algorithm of commercial GPS/GLONASS and INS where an adaptive filter for signal processing of GPS/GLONASS receiver and the 12th order Kalman filter for aided strapdown INS(SDINS) we employed. Simulation results show that the proposed adaptive filter can effectively remove a randomly occurring abrupt jump due to sudden corruption of the received satellite signal and that the Kalman filter performs satisfactorily.