• Proceedings of the Acoustical Society of Korea Conference
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• autumn
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• pp.183-186
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• 2004

Biot's theory and a modified Biot-Attenborough (MBA) model are applied to predict the dependences of acoustic characteristics on frequency and porosity in cancellous bone. The phase velocity and the attenuation coefficient predicted by both theories are compared with previous in vitro experimental measurements in terms of the mixed, the fast, and the slow waves. Biot's theory successfully predicts the dependences of phase velocity on frequency and porosity in cancellous bone, whereas a significant discrepancy is observed between predicted and measured attenuation coefficients. The MBA model is consistent with reported measurements for both dependences of phase velocity and attenuation coefficient on frequency and porosity. Based on the theoretical predictions from the MBA model, it is suggested that the attenuation coefficient of the mixed wave is dominated by the fast wave in the low-porosity region while it is dominated by the slow wave in the high-porosity region. This provides a qualitative explanation for the nonlinear relationship of attenuation of the mixed wave with porosity in cancellous bone.

• Korean Journal of Optics and Photonics
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• v.16 no.6
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• pp.560-564
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• 2005

We used the polarized light scattering spectroscopy(PLSS) to get selectively the particle size information on a surface in optically diffuse material, and we analyzed the experimental results by Mie scattering theory. We found that the PLSS was the proper method fer getting the surface information in optically diffuse material. This method is able to be used in biotechlology area for diagnostics.

• Journal of the Optical Society of Korea
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• v.7 no.2
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• pp.119-125
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• 2003

We demonstrate parametric resonance in a magneto-optical trap. When we modulate the intensity of the cooling laser at about twice the resonant frequency of the trap, the atoms in the trap are divided into two parts and oscillate with 180 degree phase difference with the finite length due to nonlinearity of the trap potential. These are the effects of general nonlinear dynamics, called the Hopf bifurcation, or limit cycle motion. The amplitude and the phase of the oscillations are measured and compared with the theoretical calculations based on simple Doppler cooling theory. The experimental results are in excellent agreement with the simulation results based on the simple Doppler cooling theory.

• Proceedings of the Acoustical Society of Korea Conference
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• 1993.06a
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• pp.190-194
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• 1993

In the ocean bubble layers play a significant role in the sound propagation as well as sound generation. Most of early works dealt with acoustic properties of the bubble layers with sharp flat boundaries. Bubble layers with sharp flat boundaries. Bubble layers with transition sublayers are more likely in the coean. In this paper a theory of sound propagation through plane bubble layers with transition sublayers at both borders was developed. It shows that the reflection and transmission coefficients depend on the thickness of transition sublayers. The theory with thicker transition sublayers shows weaker resonance properties of bubble layer. It gives better presentation for the peculiar behavior of the experimental data than that with sharp flat boundaries.

• Korean Journal of Acupuncture
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• v.27 no.3
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• pp.129-142
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• 2010

Background : The Bonghan theory is a hypothesis on the anatomical structure of the acupuncture point and meridian system. It has been regarded as a misunderstanding of the lymphatic system, or as a made-up story, for the past 40 years. Since 2002, Many studies have been published either to support the theory or to refute the old viewpoint. Objective : The purpose of this study was to find out the validity of the refutation by reviewing the publications. Methods : Searches were made from online databases (Riss4u.net, Google.com, Sciencedirect.com, Pubmed.com, baidu.com, and ci.nii.ac.jp) from 1960 to 2009. The search terms that were used were "Bonghan," "Bong han," "봉한," "thread-like structure," "KИM БOH XaHOM", "CИCTEMA KEHPAK," "鳳漢," "鳳漢管," and "鳳漢学說." References from the searched publications were also used. Results : Since the 1960s, 107 publications were identified as related works, but only 11 publications sought to refute the Bonghan theory. Two publications were researches, and nine were reviews. In the analysis of the correlation of the arguments with the publication contents, it was found that the research of G. Kellner reviewed the Bonghan system properly but that V. V. Kosmatov did not classify the ear-reflex zone as a traditional acupuncture point. For the review publications, only two reviews contained proper arguments, but seven publications were identified as broad interpretations, wrong translations, etc. Moreover, the two proper reviews were grounded on the research of G. Kellner. Conclusions : We found that the scientific origin of the refutation of the Bonghan theory is only one research by G. Kellner. This result suggest that Bonghan theory was not discussed enough to determine the invention.

• Journal of Science Education
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• v.43 no.1
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• pp.173-193
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• 2019

An expert teachers' instruction can be helpful to other teachers because good teaching effectively guides students to develop meaningful learning. Feynman is an excellent physics lecturer as well as one of the greatest physicists of the 20th century who presented and explained physics with his unique teaching style based on his great store of knowledge. However, it is not easy to capture and visualize teaching because it is not only the complex phenomena interrelated to various factors with the content to be taught but also the tacit representation. In this study, the framework of knowledge & belief based on the integrated mental model theory was used as a tool to capture and visualize complex and tacit representation of Feynman's teaching of 'The theory of gravitation,' a chapter in The Feynman Lectures on Physics. Feynman's teaching was found to go beyond the transmission of physics concepts by showing that components of the framework of knowledge & belief were effectively intertwined and integrated in his teaching and the storyline was well-organized. On the basis of these discussions, the implications of Feynman's teaching analyzed within the framework of knowledge & belief for physics teacher education are derived. Finally, the characteristics of the framework of knowledge & belief as tools for the analysis of teaching are presented.

• Proceedings of the Korean Magnestics Society Conference
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• 2007.05a
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• pp.206.2-206.2
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• 2007

• Proceedings of the Korean Magnestics Society Conference
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• 2007.05a
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• pp.231.1-231.1
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• 2007

• Proceedings of the Korean Magnestics Society Conference
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• 2015.05a
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• pp.177-177
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• 2015

• Journal of the Korean Mathematical Society
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• v.36 no.5
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• pp.847-853
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• 1999

The purpose of this paper is to develop the theory of coassociated primes and to investigate Melkersson's question [8].