• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.10
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• pp.1508-1512
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• 2012

This paper presents a relaxed stability condition for continuous-time affine fuzzy system using fuzzy Lyapunov function. In the previous studies, stability conditions for the affine fuzzy system based on quadratic Lyapunov function have a conservativeness. The stability condition is considered by using the fuzzy Lyapunov function, which has membership functions in the traditional Lyapunov function. Based on Lyapunov-stability theory, the stability condition for affine fuzzy system is derived and represented to linear matrix inequalities(LMIs). And slack matrix is added to stability condition for the relaxed stability condition. Finally, simulation example is given to illustrate the merits of the proposed method.

• Journal of the Korean Data and Information Science Society
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• v.20 no.5
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• pp.925-931
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• 2009

In this paper we propose a variance function estimation method for replicated data based on averages of squared residuals obtained from estimated mean function by the least squares support vector machine. Newton-Raphson method is used to obtain associated parameter vector for the variance function estimation. Furthermore, the cross validation functions are introduced to select the hyper-parameters which affect the performance of the proposed estimation method. Experimental results are then presented which illustrate the performance of the proposed procedure.

• Clinical and Experimental Pediatrics
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• v.50 no.5
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• pp.422-429
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• 2007

Measurement of lung function is an integral component of respiratory physiology and of clinical assessment of lung diseases in school age children and adults. Pulmonary function test of infants and children under the age of 2 years have now been standardised and are being used both in research and as an adjunct to clinical management. By contrast, until recegntly, children of preschool age, i.e. between 2-6 years represented a major challenge for pulmonary function test assessment, this particular period commonly being referred to as the 'dark ages' of Pediatric Pulmonology. Measurement of lung function in preschool-aged children is now feasible. However, much work remains to be done in standardizing how these tests are performed, and in understanding the most appropriate role for the various tests in the study of growth and development of the respiratory system and in the clinical management of children in this age group. As the field develops and the knowledge of respiratory physiology in this age group expands, investigation of different and more appropriate algorithm use in preschool children, together with development of more appropriate reference data, may result in improved disease discrimination.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.1
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• pp.172-179
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• 1996

For mechanical systems operating at high tempertature, thermal fatigue phenomenon has been recognized as a major cause of mechanical component failures. To evaluate cumulative fatigue damage as a conesquence of thermal fatugue on real time, the stress tranfer function(Green's function) approach is popularly used. The objective of this paper is to investigate the effect of thermophsical properties on the stress tranfer function. For this purpose a modified Green's function approach considering temperature-dependent thermophysical properties is proposed. Two case studies were performed and the proposed approach agrees well with full finite element analysis.

• Communications for Statistical Applications and Methods
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• v.21 no.2
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• pp.183-191
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• 2014

We define a multivariate Cauchy distribution using a probability density function; subsequently, a Ferguson's definition of a multivariate Cauchy distribution can be viewed as a characterization theorem using the characteristic function approach. To clarify this characterization theorem, we construct two dependent Cauchy random variables, but their sum is not Cauchy distributed. In doing so the proofs depend on the characteristic function, but we use the cumulative distribution function to obtain the exact density of their sum. The derivation methods are relatively straightforward and appropriate for graduate level statistics theory courses.

• The Korean Journal of Nuclear Medicine
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• v.39 no.2
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• pp.100-106
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• 2005

Non-invasive evaluation of cardiac function by nuclear medicine technologies are one of the major contribution of nuclear medicine. Gated cardiac blood pool scan was once a novel and robust technique which enabled evaluation of ventricular function. Concept of EKG gating was one of the major breakthrough in nuclear cardiology. According to the evolution of echocardiographic techniques, and as the evaluation of myocardial perfusion by perfusion SPECT became feasible, number of gated blood pool study dong in nuclear medicine laboratory is declining. And recently, evaluation of ventricular function with gated perfusion SPECT further decreased the use of gated blood pool scan. In this article, assessment of ventricular function using gated blood pool scan is discussed including some insight about the role of gated blood pool SPECT.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.17 no.10
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• pp.946-949
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• 2007

This paper discusses the lateral vibration of a beam with boundary condition of one end fixed and the other end free. The uniform beam has a solution by summation of some simple exponential functions. But if its shape is not uniform, its solution could be by Bessel's function or mathematical solution could not exist. Even if the solution of Bessel's function exists, as Bessel function is a series function, we must get the solution by numerical method. Author had proposed the solution of the matrix method by Ritz's method and a new mode shape function, and had earned the good results for a wedge beam. Hereby a vibration analysis for the tapered beam with circle cross section was executed, and so good results were showed.

• Proceedings of the KIEE Conference
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• 2001.07d
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• pp.2108-2110
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• 2001

Used analog control systems have been converted into digital control systems due to performance degradation and difficulty of maintenance. There are few domestic DCS (Distribued Control System)s that have been applied to power plant. To apply a domestic DCS to power plant, the reliability, redundacny, and fault tolerance of DCS is important. Besides those items, the control action of control function block is also important. In this paper, we describe the requirements that PID control function block has to have, and implement a PID control function block that satisfies those requirements. Finally, real control result using an implemented PID function block in thermal power plant shows the validity of an implemented PID control function block.

• Journal of the Korean Institute of Landscape Architecture
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• v.48 no.2
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• pp.34-44
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• 2020

The purpose of this study was to investigate the difference in perceptions between gardens and park functions as recognized by two groups, Group A and Group B, in order to confirm the distinction between concepts and functions and then establish the importance of individual functions. The AHP was used to analyze the importance of each group's perceptions by dividing them into garden and park, Group A and non-Group A, respectively. In Group A, the importance of garden functions were considered in descending order of importance to be cultural function, ecological function, and social function. In the general group, ecological function, cultural function, and social function also appeared, but in a different order of importance. As for the park functions, Group A recognized the importance of functions in a similar order of importance to the gardens: cultural function, ecological function, and social function. Group B thought that social function, ecological function, and cultural function have the same significance. At the major classification level, Group A and Group B emphasized the social function of the parks. Group A recognized the importance of the garden's cultural function as the most important, whereas the general group emphasized the importance of the garden's ecological function. As for the mid-class level, Group A recognized the aesthetic beauty, health, ecological environment protection, and water circulation as important functions of the garden. For Group B, the ecological environment protection, aesthetic beauty, water cycle, and health were important. The concepts and functions of gardens and parks are still largely mixed but are gradually becoming differentiated. As a follow-up study, it is important to systematically manage the functions of gardens by establishing design, construction, and monitoring DB techniques for the garden type and examine the hierarchy of various other gardens.

• Korean Journal of Child Studies
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• v.38 no.3
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• pp.33-48
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• 2017

Objective: This study examined the relationships among sleep problems, executive function and social behavior during the preschool period. In addition, the mediating role of executive function between sleep problems and social behavior was investigated. Methods: A total of 304 preschool children participated in this study. The data were collected through maternal reports. Results: First, preschoolers' sleep problems were found to be significantly related to overt aggression and prosocial behavior. Second, preschoolers with sleep problems displayed lower levels of executive function. Third, preschoolers' executive function was significantly associated with social behavior. Lastly, preschoolers' executive function fully mediated the relationship between sleep problems and overt aggression, and between sleep problems and prosocial behavior. That is, preschoolers' sleep problems had effects on overt aggression and prosocial behavior, only through the effects on executive function. Conclusion: This study contributes to the sleep literature by examining the role of executive function and emphasizes the importance of forming a healthy sleep habit during the preschool period.