• Sleep Medicine and Psychophysiology
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• v.18 no.1
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• pp.10-16
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• 2011

There has been a growing interest in sleep problems associated with attention deficit hyperactivity disorder (ADHD). In this paper, we reviewed the current literature on the underlying sleep problems associated with ADHD. Sleep problems are very common in children with ADHD. Patients with ADHD may have sleep difficulties including difficulty falling asleep, frequent night awakening, increased tiredness upon waking. Children with ADHD are associated to restless legs syndrome, periodic limb movement and sleep-disordered breathing. Screening for other psychiatric comorbidities and the side effects of medications, such as psychostimulants, is also necessary when considering sleep problems in ADHD. Sleep problems can cause a negative impact on the quality of life and emotional well-being both of children with ADHD and their parents. Many evidences suggest that assessment of sleep difficulties should be included in evaluating the patient of ADHD.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.1106-1110
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• 2004

A human sign language is generally composed of both static and dynamic gestures. Each gesture is represented by a hand shape, its position, and hand movement (for a dynamic gesture). One of the problems found in automated sign language translation is on segmenting a hand movement that is part of a transitional movement from one hand gesture to another. This transitional gesture conveys no meaning, but serves as a connecting period between two consecutive gestures. Based on the observation that many dynamic gestures as appeared in Thai sign language dictionary are of quasi-periodic nature, a method was developed to differentiate between a (meaningful) dynamic gesture and a transitional movement. However, there are some meaningful dynamic gestures that are of non-periodic nature. Those gestures cannot be distinguished from a transitional movement by using the signal quasi-periodicity. This paper proposes a hybrid method using a combination of the periodicity-based gesture segmentation method with a HMM-based gesture classifier. The HMM classifier is used here to detect dynamic signs of non-periodic nature. Combined with the periodic-based gesture segmentation method, this hybrid scheme can be used to identify segments of a transitional movement. In addition, due to the use of quasi-periodic nature of many dynamic sign gestures, dimensionality of the HMM part of the proposed method is significantly reduced, resulting in computational saving as compared with a standard HMM-based method. Through experiment with real measurement, the proposed method's recognition performance is reported.

• Journal of the Korean Institute of Intelligent Systems
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• v.24 no.6
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• pp.615-621
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• 2014

The Addiction problems have been became a social problem; the social efforts continue to solve these problems. One of those efforts, we need to establish a mathematical modeling for an addictive model to perform analysis of behavior by using this modeling. We need to process the research that can be judged before and after addictive status with result of the behavior analysis. We have to process an observation of transition from before to after addictive status. According to those necessary, this paper proposed the physical exercise model that is composed by novel second order system, which consisted of Spring-Damper-Mass system with equivalence in order to evolve an addictive equation for physical exercise. This paper also is analyzed by the behaviors for those the addictive equation of physical exercise.

• Journal of the Korea Society of Computer and Information
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• v.13 no.7
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• pp.157-164
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• 2008

In this paper we suggest a scheduling algorithm that transmits periodic traffics efficiently in tree-structured wireless sensor networks (WSNs). The related research[l] showed the problems such as increasing the energy consumption and decreasing the data throughput as the depth of tree increases. To solve these problems. we use idle time slots and avoid the redundancy at data transmission. Also we suggest the algorithm that transmits the control packet when it is similar to a previously measured data. And if emergency data is occurred, our proposed algorithm transits that data in EDP(Emergency Data Period) for reducing the wait time. The proposed algorithm shows more data throughput and less energy consumption than that of the related research.

• Journal of Environmental Science International
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• v.16 no.2
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• pp.197-202
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• 2007

Formaldehyde is a typical indoor air pollutant that has numerous adverse health problems in modern living conditions. Phytoremediation that use plants to remove contaminants from polluted media can be applied to improve indoor air quality. Two sets of experiments; 1) two rooms in newly built auditorium and 2) a bed room in 2-year-old apartment; were performed to investigate plant effects on indoor formaldehyde concentration. It was observed from the experiments that plant can help decontaminating formaldehyde at low concentration level (0.1 ppm) but the effects decreased considerably at hish concentration (1ppm). The purification effects of indoor plant also showed the periodic pattern due to its physiological activity. More purification was observed as increasing plant density in the bed room but the formaldehyde concentration returned the original concentration level in two days after removing plants. It was suggested from the results that air purification using plants is an effective means of reduction on indoor formaldehyde level, though, reduction of source is highly desirable when the concentration level is high. The results also suggest that introducing supplementary purifying aids and/or efficient ventilation could be considered due to periodic removal pattern of plant.

• Proceedings of the KSR Conference
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• 2007.11a
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• pp.903-912
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• 2007

Faults of rotating parts of a train normally generate unexpected frequency band or impulsive sound[1] which has a period when it moves with a constant speed. The former can be detected by the moving frame acoustic holography method, which visualizes sound field that is generated by a moving and emitting pure tone or band limited noise source. We have attempted to apply the method to the latter case: the periodic impulsive sound which generate different signal compared with what can be measured by the band limited noise. The signal to noise ratio which determines the success of early fault detection must also be studied with the impulsive and moving signal. This research shows how the problems related with these issues can be resolved. The main idea is that periodic impulsive signal can be expressed by infinite set of discrete pure tones. This enables us to obtain lots of holograms that visualize periodic impulsive sound field including noise by using the moving frame acoustic holography method. Therefore holograms can be averaged to improve the signal to noise ratio until having reliable information that exhibits where the impulsive sources are. Theory and experiment by using the miniature vehicle are described [Work supported by BK21 & KRRI].

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.38 no.12
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• pp.1153-1161
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• 2010

An efficient solution method for harmonic balance techniques with Fourier transform is presented for periodic unsteady flow problems. The present partially-implicit harmonic balance treats the flux terms implicitly and the harmonic source term is solved explicitly. The convergence of the partially Implicit method is much faster than the explicit Runge-Kutta harmonic balance method. The method does not need to compute the additional flux Jacobian matrix from the implicit harmonic source term. Compared with fully implicit harmonic balance method, this partial approach turns out to have good convergence property. Oscillating flows over NACA0012 airfoil are considered to verify the method and to compare with results of explicit R-K(Runge-Kutta) and dual time stepping methods.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.17 no.1 s.118
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• pp.41-47
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• 2007

Scattering fields of two dimensional acoustic waves by a circular cylinder are investigated. The present numerical approach for the acoustic scattering problem has difficulties of numerical robustness, long-time stability and suitability of far-field boundary treatments. The time-dependent periodic acoustic source is used to analyze Interference patterns between incident waves and waves reflected by the cylinder. Characteristic boundary algorithms coupled with 4th order Modified-Flux-Approach ENO(essentially non-oscillatory) schemes are employed in generalized coordinates to examine the effect of the wane frequency on the interference patterns. Non-reflecting boundary conditions, which is crustal for accurate computations of aeroacoustic problems, are used not to contaminate scattering fields by reflected waves at the outer boundary. Computed scattering fields show the circumferential acoustic modes generated by interacting between acoustic sources and scattered waves. At a lower frequency, the wave passes almost straight through the cylinder without Interacting with circular cylinder. Simulation results are presented and compared with the analytic solution. Computed RMS-pressure distribution on the cylinder wall is good agreement with exact solution.

• Structural Engineering and Mechanics
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• v.48 no.1
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• pp.103-124
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• 2013

This paper studies the static and dynamic characteristics of composite plates subjected to an arbitrary periodic load in hygrothermal environments. The material properties of composite plates are depended on the temperature and moisture. The governing equations of motion of Mathieu-type are established by using the Galerkin method with reduced eigenfunction transforms. A periodic load is taken to be a combination of axial pulsating load and bending stress in the example problem. The regions of dynamic instability of laminated composite plates are determined by solving the eigenvalue problems based on Bolotin's method. The effects of temperature rise and moisture concentration on the dynamic instability of laminated composite plates are investigated and discussed. The influences of various parameters on the instability region and dynamic instability index are also investigated. The numerical results reveal that the influences of hygrothermal effect on the dynamic instability of laminated plates are significant.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.12
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• pp.1950-1957
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• 2004

Analysis for structures composed of materials containing regularly spaced in-homogeneities is usually executed by using averaged material properties. In order to evaluate the effective properties, a unit cell is defined and loaded somehow, and its response is investigated. The imposed loading, however, should accord to the status of unit cells immersed in the macroscopic structure to secure the accuracy of the properties. In this study, mathematical description for the periodicity of the displacement field is derived and its direct implementation into FE models of unit cell is attempted. Conventional finite element code needs no modification, and only the boundary of unit cell should be constrained in a way that the periodicity is preserved. The proposed method is applicable to skew arrayed in-homogeneity problems. Homogenized in-plane elastic properties are evaluated for a few representative cases and the accuracy is examined.