• 유체기계공업학회:학술대회논문집
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• 2003.12a
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• pp.55-62
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• 2003

This paper describes the effect of the incidence angle on the turbulence structure in the wake of a turbine rotor blade at the low inlet free-stream turbulence level. For three incidence angles of -5, 0 and 5 degrees, mid-span energy spectrum as well as mid-span profiles of mean velocity magnitude and turbulence intensity are reported at three downstream locations in the wake. Vortex shedding frequencies are obtained from the energy spectrum. The result shows that as the incidence angle changes from-5 to 5 degrees, the boundary layer on the suction surface tends to be thickened, which results in widening of the wake. Strouhal numbers based on the shedding frequencies have a nearly constant value of 0.3, independent of tested incidence angles.

• Nuclear Engineering and Technology
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• v.35 no.4
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• pp.336-346
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• 2003

This study is intended to evaluate the dependency of TRU recycling characteristics on the neutron spectrum shift in a Pb-Bi cooled core. Considering two Pb-Bi cooled cores with the soft and the hard spectrum, respectively, various characteristics of the recycled core are carefully examined and compared with each other. Assuming very simplified fuel cycle management with the homogeneous and single region fuel loading, the burnup calculations are performed until the recycled core reached to the (quasi-) equilibrium state. The mechanism of TRU recycling toward the equilibrium is analyzed in terms of burnup reactivity and the isotopic compositions of TRU fuel. In the comparative analyses, the difference in the recycling behavior between the two cores is clarified. In addition, the basic safety characteristics of the recycled core are also discussed in terms of the Doppler coefficient, the coolant loss reactivity coefficient, and the effective delayed neutron fraction.

• Nuclear Engineering and Technology
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• v.55 no.11
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• pp.3956-3972
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• 2023

The floor response spectrum (FRS) is used to evaluate the seismic demand of equipment installed in nuclear power plants. In the conventional design practice of NPP structure, the FRS is simplified using the lumped-mass stick model (LMSM), assuming the floor slab as a rigid diaphragm. In the present study, to study the variation of seismic response in a floor, the FRSs at different locations were generated by 3-D finite element model, and the response was compared to that of the rigid diaphragm model. The result showed that the FRS significantly varied due to the large opening in a floor, which was not captured by the rigid diaphragm model. Based on the result, seismic fragility analysis was performed for the anchorage of a heat exchanger, to investigate the effect of location-dependent FRS disparity on the high confidence low probability of failure (HCLPF).

• Therapeutic Science for Rehabilitation
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• v.7 no.3
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• pp.9-21
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• 2018

Objective : This systematic review aimed to evaluate the global literature on the effect of early intervention for preschool children with autism spectrum disorder (ASD). Methods : A literature search of the PubMed database identified 10 studies published up to December 2017, using the following search terms: autism, autism spectrum disorder, ASD, high-function autism, high-function ASD, Asperger syndrome, pervasive developmental disorder, PDDNOS, intervention, and early intervention. Results : Early intervention for children with ASD used Applied Behavior Analysis in 8 of the 10 selected studies. The other two studies used a Sensory Integration approach and Technology-based intervention. Most studies reported positive effects on communication skills, social interaction skills, intelligence, adaptive behavior, and improved attention through early intervention. Conclusions : These results suggested a basis for early intervention for children with ASD. Further research is needed to determine the effectiveness of early intervention.

• Earthquakes and Structures
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• v.16 no.5
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• pp.563-573
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• 2019

When generating spectrum-compatible artificial ground motion in engineering practices, the effect of the variation in fitting parameters on the distribution of the peak ground displacement (PGD) has not yet drawn enough attention. In this study, a method for simulating ground motion matching for multiple targets is developed. In this method, a frequency-dependent amplitude envelope function with statistical parameters is introduced to simulate the nonstationarity of the frequency in earthquake ground motion. Then, several groups of time-history acceleration with different temporal and spectral nonstationarities were generated to analyze the effect of nonstationary parameter variations on the distribution of PGD. The following conclusions are drawn from the results: (1) In the simulation of spectrum-compatible artificial ground motion, if the acceleration time-history is generated with random initial phases, the corresponding PGD distribution is quite discrete and an uncertain number of PGD values lower than the limit value are observed. Nevertheless, the mean values of PGD always meet the requirement in every group. (2) If the nonstationary frequencies of the ground motion are taken into account when fitting the target spectrum, the corresponding PGD values will increase. A correlation analysis shows that the change in the mean and the dispersion values, from before the frequencies are controlled to after, correlates with the modal parameters of the predominant frequencies. (3) Extending the maximum period of the target spectrum will increase the corresponding PGD value and, simultaneously, decrease the PGD dispersion. Finally, in order to control the PGD effectively, the ground motion simulation method suggested in this study was revised to target a specified PGD. This novel method can generate ground motion that satisfies not only the required precision of the target spectrum, peak ground acceleration (PGA), and nonstationarity characteristics of the ground motion but also meets the required limit of the PGD, improving engineering practices.

• Journal of The Korean Society of Integrative Medicine
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• v.10 no.3
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• pp.95-105
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• 2022

Purpose : This study aims to systematically review the methods of occupational therapy intervention in children with autism spectrum disorders having sleep disorders and evaluate the improvements with intervention effects, based on experimental studies of children with sleep disorders. Methods : Studies published overseas from January 2011 to June 2021 were searched from a total of two databases. Science Direct and OTseeker. The five selected studies were analyzed by dividing them into age, number, intervention period, intervention type, intervention effect, evaluation tool, research design type, and evidence level. Results : The total number of subjects was 182, 95 subjects in ther experimental group, and 87 in the control group. The interventions included weighted blankets, swimming, and sleep education for parents. Ther interventions were found to increase total sleep time, improve mood when waking up, reduce sleep anxiety, reduce sleep time, reduce the number of waking up of during sleep, and reduce sleep resistance behavior. Conclusion : Many people have sleep disorders, with or without disabilities, and the number is gradually increasing. Consequently, research on occupational therapy intervention in children with autism spectrum disorder are actively conducted in foreign countries, and these interventions have a positive effect. Based on the results of this study, it can be concluded that such occupational therapy intervention studies are necessary for children with autism spectrum disorder with sleep disorders in Korea. In addition, further research on the quality of life of parents of children with autism spectrum disorders due to sleep disorders and their methods are required.

• Journal of The Korean Astronomical Society
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• v.38 no.2
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• pp.175-178
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• 2005

We show that next-generation galaxy surveys such as KAOS (the Kilo-Aperture Optical Spectro-graph)will constrain dark energy even if the baryon oscillations are missing from the monopole power spectrum and the bias is scale- and time-dependent KAOS will accurately measure the quadrupole power spectrum which gives the leading anisotropies in the power spectrum in redshift space due to peculiar velocities, the finger of God effect, as well as the Alcock-Paczynski effect. The combination of monopole and quadrupole power spectra powerfully breaks the degeneracy between the bias parameters and dark energy and, in the complete absence of baryon oscillations ($\Omega$b = 0), leads to a roughly $500\%$ improvement in constraints on dark energy compared with the monopole spectrum alone. As a result, for KAOS the worst case with no oscillations has dark energy errors only mildly degraded relative to the ideal case, providing insurance on the robustness of KAOS constraints on dark energy. We show that nonlinear effects are crucial in correctly evaluating the quadrupole and significantly improving the constraints on dark energy when we allow for multi-parameter scale-dependent bias.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.200-200
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• 2011

Although the cut-off probe, a precise measurement method for the electron density, is widely used in the industry, the physics on the wave spectrum of the cut-off is not understood yet, only cut-off point frequency containing the information of electron density has been analyzed well. This paper analyzes the microwave frequency spectrum of the cut-off probe to see the physics behind using both microwave field simulation (CST Microwave Studio) and simplified circuit simulation. The result shows that the circuit model well reproduces the cut-off wave spectrum especially in the low frequency regime where the wavelength of the driving frequency is larger than the characteristic length and reveals the physics of transmission characteristics with frequency as resonances between vacuum, plasma and sheath. Furthermore, by controlling the time domain in solver of the microwave simulator, the cut-off like transmission peaks above the cut-off frequency which has been believed as cavity effect is verified as chamber geometry effect. The result of this paper can be used as the basis for the improvement of cut-off probe.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.147-147
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• 2012

Cutoff probe has been used for measuring a plasma density using the cutoff peak which is located at the plasma frequency in the low pressure plasma. However, research on analysis of low frequency region of transmission microwave frequency (TMF) spectrum does not performed even though important plasma parameters are located in the low frequency region, i.e., ion plasma frequency and collision frequency. In this research, we analyzed the low frequency region of the TMF spectrum. Experimental results reveal the effect of plasma parameters on the low frequency region on the TMF spectrum. Based on the response of TMF spectrum from changing of plasma parameters, deduction of the plasma parameters was tried. This comprehensive analysis of TMF spectrum expands applicable area of cutoff probe.

• Korean Journal of Child Studies
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• v.35 no.6
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• pp.1-23
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• 2014

The purpose of this study was to develop the Cognitive Spectrum Program, a cognitive development program designed to increase children's IQ. The effect of this program was verified using a nonequivalent control group design. The subjects were 127 5-8 year old children. 56 children were assigned to the experimental group and 71 children to the control group. The experimental group participated in thirteen 90 min. long sessions. Quantitative analyses using SPSS WIN 18.0 and qualitative analyses were carried out. The results were as follows: First, this Cognitive Spectrum Program was shown to be effective in improving cognitive development. Second, the amount of improvement in cognitive development was found to be predictive of the amount of change in socioemotional development, demonstrating that attention deficits and overall problem behaviors were greatly reduced among the children whose IQ was improved by this program. This finding was also verified through qualitative analyses.