• The Bulletin of The Korean Astronomical Society
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• v.40 no.1
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• pp.78.2-78.2
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• 2015

Powered by a supermassive black hole, active galactic nuclei (AGNs) are characterized by prominent emission lines including Blamer lines. The unification scheme of AGNs requires the existence of a thick molecular torus that may hide the broad emission line region. In this configuration, it is expected that the far UV radiation from the central engine can be Raman scattered by neutral hydrogen to reappear around Balmer lines which can be identified observationally with broad Balmer wings. Another mechanism that can form Balmer wings is considered by invoking a fast moving medium around the central engine. In this presentation, we produce Balmer wings that are formed through Raman scattering and also those expected from a fast moving emission flow. It is noted that Raman Balmer wings exhibit stronger red part whereas the opposite behavior is seen in the Balmer wings obtained from a fast moving emission flow.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.9 no.3
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• pp.113-119
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• 1984

In the scattering of a monochromatic plane wave from a dielectric column oscillating sinusoidally prependicular to its axis, one could assume that the boundary moves with a uniform velocity equal to its instantaneous oscilaating velocity. The scattered fields are abtained according to the postulates of special relativitiy and extended for the osdillating period. The angle distribution of average scattering radiation, the average of total scattering cross sections and radar cross sections for a period are illustrated as the function of the relative maximum oscillating velocity and the incident angles of plane waves.

• Journal of radiological science and technology
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• v.10 no.1
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• pp.37-41
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• 1987

Authors could recognize surrounding areas induding target area by the observable film density with spot radiography using Cu mask and also, radiographic images maintained high quality. Spot radiography has been utilized for a long time for the purpose of observing detail image by the control of scattered radiation. But it has been difficult to know body part in general spot radiography. Therefore it is thought that attempt to use Cu mask in spot radiography is very advantageous in a clinical examinations.

• The Bulletin of The Korean Astronomical Society
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• v.41 no.2
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• pp.35.2-35.2
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• 2016

Lyman alpha photons emitted from the early generation galaxies are scattered through the intergalactic medium, and can be observed as Lyman alpha emitting sources. We examine the Lyman alpha line transfer mechanism by tracing the random scattering histories of Lyman alpha photons in the intergalactic medium of the early universe. The density and ionization fields are based on the 3D map by N-body + radiation transfer simulations of the epoch of reionization. The calculation is compared with analytical models, too. The emergent line profile and the size of the Lyman alpha blob are strongly tied to the density and ionization environment, likely to give constraints when high-z Lyman alpha blobs are observed.

• Proceedings of the KIEE Conference
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• 2001.07c
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• pp.1835-1837
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• 2001

The interference of electromagnetic waves in factory is increasing according with development of industrial society and many use of electrical machinery. Electromagnetic wave is defined as the electrical and magnetic field formed by electrical and electronic equipment used in daily lives, which indiscriminatingly affects the human health and operation of machinery. The electromagnetic spectrum ranges from the shorter wavelengths(including gamma and x-rays) to the longer wavelengths(including microwaves and broadcast radio waves). Radiation that is not absorbed or scattered in the atmosphere can reach and affect on the operation of machine. In this study, electromagnetic wave that is interfered to the machine and human is detected in factory, and decrease method of electromagnetic wave interference is studied.

• Proceedings of the Acoustical Society of Korea Conference
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• spring
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• pp.403-408
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• 1999

In this paper, ultrasonic tomography by the Mode-Converted Rayleigh wave (MCRW) in the back-scattered direction is presented. When a beam with a short pulse and narrow beam width enters a reflector with smooth surface, in general, two major arrivals can be observed in the output waveform: the specular reflection and the radiation of the MCRW from the reflector surface. The time-delay between the two waves is relatively large and thus can be measured easily. This large time-delay is due to the fact that the MCRW is slower than incident wave. In our method, this large time- delay is used for ultrasonic image reconstruction. To effectively detect the MCRW, the arrayed-receiving transducers are circularly arranged around the transmitter. In addition, a deconvolution method is employed to remove specular echo signals for reconstructing the MCRW image.

• Proceedings of the Optical Society of Korea Conference
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• 2000.02a
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• pp.146-147
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• 2000

The electromagnetic wave scattering from active objects has only recently attracted attention.$^{(1).(3)}$ Theoretical studies have considered normal-incidence plane-wave interactions with active dielectric cylinders with the prediction of large enhancements in the scattered field for bound mode structures. According to the theory of the electromagnetic wave scattering from a dielectric cylinder, the eigenvector solutions are discrete and have both guided (non-radiative) and leaky (radiative) mode solutions. By using an anti-guiding (leaky) structure instead of a guided structure and scattering at oblique incident angles near critical angle, the scattering resonances predicted by theoretical studies were obtained for the first time. A fine-grained scan of the plane-wave incident angle a reveals the existence of discrete scattering resonances. The diameter and real part of the index of refraction determine the resonant conditions and the imaginary part of the refractive index has a threshold value to make mode up for its radiation loss. The cross coupling between transverse electric (TE) and transverse magnetic (TM) modes is clearly detected for both active and passive scattering as theoretically expected. (omitted)

• Proceedings of the Korean Society of Medical Physics Conference
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• 1999.11a
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• pp.330-333
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• 1999

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.521-521
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• 2013

Collective Thomson scattering (CTS) system is being developed in KAERI based on high power gyrotrons. CTS is a promising diagnostic method to measure fast ion distributions and potentially the fusion product alpha particles in magnetically confined plasmas. By utilizing millimeter-waves from high power gyrotrons as a probing beam, spatially and temporally resolved 1-D ion velocity distributions can be obtained from the scattered radiation with less scattering geometrical constraints. The pulse modulation of gyrotrons enables to separate scattering signal from ECE background noises. The feasibility was assessed with the calculation of spectral density functions under the condition of KSTAR plasmas. Further CTS system requirements are also discussed.

• Journal of The Korean Astronomical Society
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• v.22 no.2
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• pp.141-160
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• 1989

In order to derive time dependence of the atmospheric diffuse light, which consists of the airglow continuum emission and diffusely scattered radiations of the intergrated starlight, the diffuse Galactic light, and the zodiacal light, we have analyzed the meridian scan observations of the sky brightness at $5,080\;{\AA}$ and $5,300\;{\AA}$. Amplitude of the time-variation becomes larger for lower elevation, and maximum amplitude is found to be about $50\;S_{10}(V)_{G2V}$ at elevation $10^{\circ}$. The atmospheric diffuse radiation attains maximum brightness at around midnight, and afterward it decreases slowly with time. The time-variations for the two wavelengths are similar to each other. The observed brightness distribution of the diffuse light along the zenith distance is fitted to an empirical relation of two parameters. By making the two parameters time-dependent, we describe the spatial and time variations of the atmospheric diffuse light. This enables us to make time dependent correction for the atmospheric diffuse component in the reduction of zodiacal light brightness.