• Publications of The Korean Astronomical Society
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• v.30 no.2
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• pp.289-292
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• 2015

Most of the stars in the Galaxy are in binary systems. Binaries should be possible as the hosting stars of planets. Searching for planetary companions to binaries, especially evolved close binary stars, can provide insight into the formation and the ultimate fate of circumbinary planets and shed light on the late evolution of binary stars. In order to do this, we have chosen some post common envelope binaries including sdB-type eclipsing binaries and detached WD+dM eclipsing binaries as our targets and monitored them for several years. In this paper, we will present some of our new observations and results for three targets, NSVS 07826147, NSVS14256825 and RR Cae.

• Communications of Mathematical Education
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• v.16
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• pp.1-65
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• 2003

The focus of this article is on the process of cultivating students' interests so that they come to view mathematics as an activity worthy of their engagement. We first define and operationalize the notion of interests, in the process developing a perspective in which they are seen to be generative, to evolve, and to be deeply cultural. We concretize this perspective by presenting an analysis of a classroom design experiment that documents both the process by which the students' interests evolved and the means by which these developments were supported. We then frame the analysis as a case in which to tease out the implications for a nascent design theory of mathematical interests and in doing so give particular attention to the issue of equity in students' access to significant mathematical ideas

• Journal of Society of Preventive Korean Medicine
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• v.8 no.1
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• pp.155-161
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• 2004

The average life span is expanded due to the development of modem society, material and cultural life and increasing level of public health. This means that the aging society is rapidly progressing. Geniatric diseases also have increased due to increasing of the aged population. Along with an increase of the aged patient, the anti-aging, prevention of geniatric disease and quality of life is tending high on social concern and medical issues. Many reports showed the evidence to the positive anti-aging effect of Oriental medicine. Qigong therapy, a kind of Oriental medicine, has been used to prevent aging and life prolongation with positive effect for many thousand years. Therefore, qigong practice is popular and common to middle age and old age in China.

• Geomechanics and Engineering
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• v.6 no.6
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• pp.545-560
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• 2014

For slope stability analysis, an alternative to the classical limit equilibrium method (LEM) of slices is the shear strength reduction method (SRM), which can be integrated into finite element analysis or finite difference analysis. Recently, probabilistic analysis of earth slopes has been very attractive because it is capable to take the soil uncertainty into account. However, the SRM is less commonly extended to probabilistic framework compared to a variety of probabilistic LEM analysis of earth slopes. To overcome some limitations that hinder the development of probabilistic SRM stability analysis, a new procedure based on recursive algorithm FORM with sensitivity analysis in the space of original variables is proposed. It can be used to deal with correlated non-normal variables subjected to implicit limit state surface. Using the proposed approach, a probabilistic finite element analysis of the stability of an existing earth dam is carried out in this paper.

• Journal of Power Electronics
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• v.16 no.1
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• pp.310-318
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• 2016

This paper presents a new orthogonal signals generator (OSG) with DC Offset rejection for implementing a phase locked loop (PLL) in single-phase grid-connected power systems. An adaptive filter (AF) based on the least mean square (LMS) algorithm is used to constitute the OSG in this study. The DC offset in the measured grid voltage signal can be significantly rejected in the developed OSG technique. This generates two pure orthogonal signals that are free from the DC offset. As a result, the DC offset rejection performance of the presented single-phase phase locked loop (SPLL) can be enhanced. A mathematical model of the developed OSG and the principle of the adaptive filter based SPLL (AF-SPLL) are presented in detail. Finally, simulation and experimental results demonstrate the feasibility of the proposed AF-SPLL.

• Proceedings of the KIPE Conference
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• 2007.07a
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• pp.438-440
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• 2007

This paper shows a new kind of push-pull switching converter for fuel-cell system and analyses the connected characteristics of it. In these characteristics, we are concerned about the high harmonic rate of output current, we also have designed the filter system for the inverter. Besides, the characteristics should be certified better if the ripple of the fuel-cell output current has been eliminated.

• Journal of Power Electronics
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• v.13 no.3
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• pp.479-486
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• 2013

This paper presents a control strategy for distributed systems, which can be used in islanded microgrids. The control strategy is based on the droop method, which uses locally measured feedback to achieve load current sharing. Instead of the traditional droop method, an improved one is implemented. A virtual inductor in the synchronous frame for three-phase inverters is proposed to deal with the coupling of the frequency and the amplitude related to the active and reactive power. Compared with the traditional virtual inductor, the proposed virtual inductor is not affected by high frequency noises because it avoids differential calculations. A model is given for the distributed generation system, which is beneficial for the design of the droop coefficients and the value of the virtual inductor. The effectiveness of the proposed control strategy is verified by simulation and experiment results.

• Proceedings of the KSRS Conference
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• 2003.11a
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• pp.1346-1348
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• 2003

In this paper, the interferometric coherence was estimated and the amplitude intensity was extracted using the repeat-pass interferometric data, acquired by European Remote Sensing Satellite 1 and 2. Then discrimination and classification of surface land types in Zhangjiakou test site, Hebei Province were carried out based on the coherence estimation and the intensity extraction. Seven types of land were discriminated and classified, including in two different types of meadows, woodland, dry land, grassland, steppe and water body. The backscatter and coherence characteristics of these land types on the multi-temporal images were analyzed, and the change of surface features with time series was also discussed.

• Proceedings of the KSRS Conference
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• 2003.11a
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• pp.591-593
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• 2003

The study demonstrates the data extraction capabilities from the simulated ROCSAT-2 image by manual delineation. The GIS data are able to identify as fifteen categories of the classes I & II for the simulated ROCSAT-2 and SPOT image data. The areas of the paddy are identified almost the same results for both cases, but the arid farmland are identified differently about 30%. The ROCSAT-2 case can be also identified as seven more categories of the class III, but SPOT-4 case cannot.

• Journal of Industrial and Engineering Chemistry
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• v.68
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• pp.380-386
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• 2018

A sustainable method was developed for the upgrade of biomass derived vanillin (a typical model compound of lignin) into the potential liquid biofuels over a layered double hydroxide supported Pd catalyst (abbreviated as CoAl-LDH/Pd). The CoAl-LDH/Pd catalyst showed high catalytic activity towards the hydrodeoxygenation of vanillin into 2-methoxy-4-methylphenol (MMP) under mild conditions in aqueous media. High MMP yield up to 86% was produced at $120^{\circ}C$ after 4 h. Kinetic studies revealed that the rate-determining step for the hydrodeoxygenation of vanillin was the hydrogenolysis of vanillyl alcohol. More importantly, the CoAl-LDH/Pd catalyst was highly stable without the loss of activity.