• Journal of applied mathematics & informatics
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• v.6 no.3
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• pp.697-726
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• 1999

In this paper we develop a now procedure to control stepsize for linear multistep methods applied to semi-explicit index 1 differential-algebraic equations. in contrast to the standard approach the error control mechanism presented here is based on monitoring and contolling both the local and global errors of multistep formulas. As a result such methods with the local-global stepsize control solve differential-algebraic equation with any prescribed accuracy (up to round-off errors). For implicit multistep methods we give the minimum number of both full and modified Newton iterations allowing the iterative approxima-tions to be correctly used in the procedure of the local-global stepsize control. We also discuss validity of simple iterations for high accuracy solving differential-algebraic equations. Numerical tests support the the-oretical results of the paper.

• Korean Journal of Child Studies
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• v.24 no.6
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• pp.1-14
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• 2003

In contrast with Zelazo and Frye (1997) who argued that preschool children lack the conscious representation and executive functioning needed to solve problems based on conflicting rules, Bilaystok (1999) identified analysis(representation) and control(selective attention) as components of language processing and has shown that control develops earlier in bilingual than in monolingual children. This study investigated the effects of bilingualism on children's cognitive ability and language development by comparing Korean- Chinese bilingual with Chinese monolingual children in Yanji. Sixty children 3 to 5 years of age in each of the bilingual and the monolingual groups in Yanji, China participated in ths study. Results showed that bilingual were more advanced than monolingual children in solving problems requiring a high level of control, confirming Bialystok's(1999) results.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.13 no.5
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• pp.422-428
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• 1988

An iterative learning control system is a control system which makes system outputs follow desired outputs by iterating its trials over a finite time interval. In a discrete time system, we proposed one method in which present control inputs can be obtained by a linear combination of the input sequence and time-shifted error sequence at previous trial. In contrast with a continous time learning control system which needs differential opreration of an error signal, the time shift operation of the error sequence is simpler in a computer control system and its effectiveness is shown by a simulation.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.8
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• pp.38-45
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• 1999

The 2-trowel type concrete floor finishing robot can move in any direction by adjusting the posture or trowels without any wheels. Since the quality of the smoothed and polished concrete floor is determined by plastering speed, we need to control the velocity of the robot. However, we cannot use the typical motion control method because it is very difficult to measure the velocity of the robot, in contrast to the mobile robots with wheels. To overcome this difficulty, the following are studied in this paper: we found that the robot dynamics has the disturbance depending on its translational speed, and showed that there exists the saturated velocity of the robot which is set by the posture of the trowels, and obtained the relationship between the saturated velocity and the posture in the translation. The result enables us to control the motion of the robot only by adjusting the posture of trowels without measuring the velocity of the robot. Currently, we built the troweling robot and are experimenting its performance with the proposed motion control method.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.45 no.2
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• pp.175-184
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• 1996

In this paper the newly developed discrete-time adaptive sliding mode control method is proposed and applied to the power system stabilization problem. In contrast to the conventional continuous-time sliding mode controller, the proposed method is developed in the discrete-time domain and based on the input/output measurements instead of the continuous-time and the full-states feedback, respectively. Because the proposed control method has the adaptivity property in addition to the natural robustness property of the sliding mode control, it is possible to design the power system stabilizer which can overcome both the minor variations of the parameters of the power system and the diverse operating conditions and faults of the power system. Mathematical proof and the various computer simulations are done to verify the performance and stability of the proposed method.

• 한국정보디스플레이학회:학술대회논문집
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• 2004.08a
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• pp.799-802
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• 2004

In this paper, the active backlight control technology with data processing algorithm was developed in order to improve image quality for IPS-mode LCD-TV applications. The image blinking problem caused by repeatedly abrupt change of the backlight luminance was solved by algorithms-Fba(Flexible Boundary algorithm) and Cfa(Cumulative Feedback algorithm)-and the optimized number and space of backlight dimming steps based on perception. In the IPS-mode 42" TFT-LCD panel, the dynamic contrast ratio can be more than twice the typical level by means of lower block luminance and higher white luminance. Additionally, Power consumption and LCD temperature was decreased.

• Journal of Biomedical Engineering Research
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• v.28 no.2
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• pp.199-204
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• 2007

In digital radiography, to improve the contrast of digital radiography image, the multi-scale nonlinear amplification algorithm based on unsharp masking is one of the major image enhancement algorithms. In this paper, we used the Laplacian pyramid to decompose a digital radiography(DR) image. In our simulation, the DR image was decomposed into seven layers and the coefficients of the each layer was amplified with nonlinear function. We also imported a noise containment algorithm to limit noise amplification. To enhance the contrast of image, we proposed a new adaptive non-linear gain amplification coefficients. As a result of having applied to some clinical data, a detail visibility was improved significantly without unacceptable noise boosting. Images that acquired with the proposed adaptive non-linear gain coefficients have shown superior quality to those that applied similar gain control method and expected to be accepted in the clinical applications.

• Journal of Korea Multimedia Society
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• v.7 no.8
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• pp.1046-1057
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• 2004

An image enhancement method using both homomorphic transformation and multiscale decomposition is proposed. The original image is first transformed to homomorphic domain by taking the logarithm, is then separated to multiscales. These multiscales are combined with weighting. The combined signal is exponentially transformed back into intensity domain. In homomorphic domain, the magnitude control of low frequency component make change the dynamic range, and the magnitude control of the other frequency components contribute to enhancement of the contrast. The "${\AA}$ trous" algorithm, which has a simple and efficient scheme, is used for multiscale decomposition. The performance of proposed method is verified by simulation.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.1
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• pp.191-193
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• 2014

The aim of this study was to examine the trend of ovary cancer incidence from 1999 to 2010 in China and predict the burden up to 2020. Crude incidence, age specific incidence and age-adjusted incidence rates were calculated. Joinpoint regression was performed to obtain estimated annual percentages and Bayesian age-period-cohort modeling was used to predict the incidence rate until the year 2020. In China, the crude rate of ovary cancer was 7.91/100,000 and the age-adjusted rate was 5.35/100,000 overall during period 1999-2010. The rates in urban regions were higher than in rural regions. A significant rising trend during 1999-2006 was followed by a drop during 2006-2010 in age-adjusted rates for urban females. In contrast, constant rise was observed in rural women. The decrease in ovary cancer of urban areas tended to be restricted to women aged 50 years and younger. In contrast, increases of ovary cancer in rural areas appeared in virtually all age groups. Although the age-adjusted incidence rate for ovary cancer was predicted to be reduced after year 2011, the crude rate was likely to be relative stable up to 2020. The burden of ovary cancer in China will continue to be relative stable due to the aging population.

• Journal of Institute of Control, Robotics and Systems
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• v.10 no.7
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• pp.590-596
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• 2004

A passivity-based dynamic output feedback controller design is considered for a finite collection of non-square linear systems. Design of a single controller for a set of plants i.e. simultaneous stabilization is an important issue in the area of robust control design. We first determine a squaring gain matrix and an additional dynamics that is connected to the systems in a feedforward way, then a static passivating control law is designed. Consequently, the actual feedback controller will be the static control law combined with the feedforward dynamics. A necessary and sufficient condition for the existence of the parallel feedforward compensator is given by the static output feedback formulation. In contrast to the previous result [1], a technical condition for constructing the parallel feedforward compensator is removed by proposing a new type of the parallel compensator.