• Proceedings of the Optical Society of Korea Conference
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• 2009.02a
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• pp.449-450
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• 2009

The spatial coherence and propagation property of laser beam propagating through several optical components were studied experimentally by using the measurement of Wigner distribution function. It is shown experimentally that the Wigner function measurement yields total degree of coherence, beam quality parameter, and the near and the far field information of the propagating beam. More complete characterization of the laser beam was achieved by applying the Schmidt mode decomposition to the Wigner distribution function, spatial coherence function and directional coherence function. Fine details of coherence property are understood by the characteristics of the contributing eigenmodes.

• Korean Journal of Optics and Photonics
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• v.15 no.3
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• pp.200-213
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• 2004

The realization of partially coherent Gaussian Schell-model beams with isotropic cross section and anisotropic degree of coherence function is investigated theoretically. An optical system is devised to transform diffused light generated by passing the Gaussian beam of the He-Ne laser thorough a rotating holographic diffuser to the partially coherent Gaussian Schell-model beam with isotropic cross section and anisotropic degree of coherence function. Analytic design equations are formulated and design examples are presented.

• Current Optics and Photonics
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• v.1 no.4
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• pp.271-277
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• 2017

Based on the extended Huygens-Fresnel principle, the analytical propagation formulae for spectrally partially coherent Gaussian Schell-model pulsed (SPGSMP) beams propagating in turbulent atmosphere have been derived. The influences of the parameters for turbulent atmosphere and SPGSMP beams on the on-axis and off-axis spectral shift and degree of coherence for SPGSMP beams propagating in turbulent atmosphere have been analyzed, using numerical calculations. The obtained results have potential applications for SPGSMP beams in free-space optical communication and laser lidar.

• Asian Journal of Innovation and Policy
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• v.2 no.1
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• pp.37-62
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• 2013

Many scholars have persevered in understanding the convergence process by developing a measurement that reflects the characteristics of the convergence phenomenon as a process. Recently a series of studies suggested a framework in terms of diversity and coherence. However, an index for coherence is required to reflect the vital features of the conceptual definition, and thus a new index for coherence is proposed in this paper. Technology Convergence Index combines diversity and coherence and indicates the degree of the convergence in information computer technology (ICT), biotechnology (BT) and nanotechnology (NT) sectors. The index can not only be used to track each technology field that consists of a major technology sector, but also to compare other leading countries. Based on a comparison study between the United States and South Korea, the degrees of technology convergence of Korea in ICT, BT, and NT sectors have ameliorated.

• Bulletin of the Korean Chemical Society
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• v.28 no.4
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• pp.607-612
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• 2007

Relationship between charge transfer mechanism and quantum coherence has been investigated using a realtime quantum dynamics approach. In the on-the-fly filtered propagator functional path integral simulation, by separating paths that belong to different mechanisms and by integrating contributions of correspondingly sorted paths, it was possible to accurately obtain quantitative contribution of different transport mechanisms. For a 5'-GAGGG-3' DNA sequence, we analyze charge transfer processes quantitatively such that the governing mechanism alters from coherent to incoherent charge transfer with respect to the friction strength arising from dissipative environments. Although the short DNA sequence requires substantially strong dissipation for completely incoherent hopping transfer mechanism, even a weak system-environment interaction markedly destroys the coherence within the quantum mechanical system and the charge transfer dynamics becomes incoherent to some degree. Based on the forward-backward path deviation analysis, the coherence variation depending on the environment is investigated numerically.

• Journal of the Korean Data Analysis Society
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• v.20 no.6
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• pp.2771-2779
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• 2018

The recent financial crises cause the co-movement and transmit the risk across different markets and assets. It is well known that market fear affects the quality of credit in the financial markets. In this context, this study examines the co-movement between the volatility index (VIX) of the Chicago Board Options Exchange (CBOE), or VIX, and six emerging countries' credit default swaps (CDSs), by implementing wavelet coherence. Our research aims at revealing whether the VIX can be used to hedge against the bubble behavior of the CDS market in different investment holding periods (short-run, medium-run, and long-run), as well as whether either market can be used to manage and hedge overall market downside risks. The wavelet coherence results show a high degree of co-movement between the VIX and CDS during the 2007-2009 global financial crisis, across the 16-64 weeks' frequency band. In addition, we observe that the positive correlation between the VIX and the CDS markets, implying that the market turmoil intensifies the co-movement between the VIX and CDS markets.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.11a
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• pp.75-81
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• 2006

Recently, customers interest about noise of household electric appliance is growing. so, designer of product must study to reduce noise of product. Specially, in case of household electric appliance such as washing machine, there was consumers' complaint about noise that is radiated under dehydrating condition. But, in the case of washing machine, identification of noise source is not easy when washing machine is under dehydrating condition. Because various noise source influence each other, it is difficult to find out pure contribution degree about output noise. Multi-Dimensional Spectral Analysis(MDSA) is method that can remove correlation between inputs each other and express pure contribution degree about output of single input. So in this study, we analyzed contribution of each noise source on transfer pass of noise that is radiated at dehydration of washing machine using MDSA.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.05a
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• pp.127-133
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• 2002

After the vibration source is searched in optical disk drive as an information storage device broadly used the influence of it against FES(Focusing Error Signal) which is a kind of positioning error of pick up from the circuit is carefully examined. For that Purpose, partial coherence function method is applied on a simple multi-degree of freedom model made for the theoretical verification and it is practically introduced in optical disk drive for analyzing the effect of vibration source. Finally, partial coherence output spectrum is attentively observed in order to know which vibration source is a great influence on FES.

• Korean Journal of Optics and Photonics
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• v.3 no.3
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• pp.161-166
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• 1992

The s-polarized laser beam is incident with an angle ~$-30^{\circ}$ to a uniformly rotating rough metal surface and the degree of second order temporal coherence $g_{s}^{(2)}(\tau)$ of the backscattered wave, which has the same polarization with the incident laser beam, is measured. The contribution of shot noise involved in the measurement of $g_{s}^{(2)}(0)$ is subtracted from the photoelectric signal to obtain the accurate value of $g_{s}^{(2)}(0)$.At each scattering angle$\theta_{s}$에서$g_{s}^{(2)}(\tau)$ is almost consistent with the function {1+exp($-\tau^2/\tau_0^2$)}, which is the same result with the case of the laser speckle formed by scattering on the rotating ground glass suface. In addition, a peak in the angular distribution of $\tau_0$ is observed with the maximum at$\theta_s=34^{\circ}$.It is found that the rough metallic scattering with multiple scattering over than 10% has the same function of the degree of second order temporal coherence with that of the ground glass surface scattering where the multiple scattering is ignorably small.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.16 no.5
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• pp.83-89
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• 2016

In this paper, we apply the complementation principle of five prime substances to reduce the phase interference. The transmitter and receiver match the concepts of co-operative and conflict to the direct and indirect signals. The result shows we investigate the proposed network topology such as 5 prime substances (5 user networks). The key observation is that optimal symmetric degree of freedom (DoF) can be achieved for 5 user network with different channel coherence times by adaptively selecting the interference alignment scheme via controlling the alignment feasibility of the transmitted signals. Theoretical results demonstrate the effectiveness of the proposed 5 user networks are well matched to the wireless mobile channel environment to achieve the symmetric DoF for different channel coherence times which ensures that the proposed networks are applicable for dense wireless network applications. Modulo 3 functionality in 5 user network topology makes it easier for the transmitter cooperation to achieve the DoF of 2/3 with the help of the interference alignment schemes.