• 방사선산업학회지
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• 제9권4호
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• pp.199-207
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• 2015

Typical radiation cross-linked hydrogels has the characteristic that high water content, but low emission efficiency of active ingredients. Therefore, the hydrogel was prepared by the addition to collagen, which is closely related to the formation of skin wrinkles in biocompatibility and highly water-soluble carboxymethyl cellulose sodium salt (CMC) in order to preparation of hydrogels has excellent emission efficiency of active ingredients. Hydrogels were prepared by dissolving CMC and collagen each of 0.5%, 10% concentration in deionized water. Then, prepared hydrogels are performed by gamma-radiation at 1, 3, 5 kGy irradiation dose. The results showed that the gel fraction of after irradiated 3 kGy hydrogel was higher than before irradiated gelation as long as the 55.3%. The swelling rate of irradiated 3 kGy hydrogel was lower than the non-irradiated sample. The compressive strength of 3 kGy irradiated hydrogel was the highest. The visco-elastic did not show any significant differences, even after irradiation. The CMC hydrogel in this study suggested a potential use as a material for the mask pack for improved emission efficiency of the active ingredient and anti-wrinkles.

• 천문학회지
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• 제40권1호
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• pp.1-7
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• 2007

About 10 percent of quasars are known to exhibit deep broad absorption troughs blueward of prominent permitted emission lines, which are usually attributed to the existence of outflows slightly above he accretion disk around the supermassive black hole. Typical widths up to 0.2c of these absorption roughs indicate the velocity scales in which special relativistic effects may not be negligible. Under he assumption of the ubiquity of the broad absorption line region in quasars, the broad emission line flux will exhibit Thomson scattered components from these fast outflows. In this paper, we provide our Monte Carlo calculation of linear polarization of singly Thomson scattered line radiation with the careful considerations of special relativistic effects. The scattering region is approximated by a collection of rings that are moving outward with speeds ${\upsilon}=c{\beta}<0.2c$ near the equatorial plane, and the scattered line photons are collected according to its direction and wavelength in the observer's rest frame. We find that the significantly extended red tail appears in the scattered radiation. We also find that the linear degree of polarization of singly Thomson scattered line radiation is wavelength-dependent and hat there are significant differences in the linear degree of polarization from that computed from classical physics in the far red tail. We propose that the semi-forbidden broad emission line C III]1909 may be significantly contributed from Thomson scattering because this line has small resonance scattering optical depth in the broad absorption line region, which leads to distinct and significant polarized flux in this broad emission line.

• 천문학회지
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• 제37권4호
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• pp.193-197
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• 2004

Anomalies in the far-infrared [C II] 158 ${\mu}m$ line emission observed in the central one-kiloparsec regions of spiral galaxies are reviewed. Low far-infrared intensity ratios of the [C II] line to the continuum were observed in the center of the Milky Way, because the heating ratio of the gas to the dust is reduced by the soft interstellar radiation field due to late-type stars in the Galactic bulge. In contrast, such low line-to-continuum ratios were not obtained in the center of the nearby spiral M31, in spite of its bright bulge. A comparison with numerical simulations showed that a typical column density of the neutral interstellar medium between illuminating sources at $hv {\~} 1 eV $ is $N_H {\le}10^{21}\;cm^{-2}$ in the region; the medium is translucent for photons sufficiently energetic to heat the grains but not sufficiently energetic to heat the gas. This interpretation is consistent with the combination of the extremely high [C Il]/CO J = 1-0 line intensity ratios and the low recent star-forming activity in the region; the neutral interstellar medium is not sufficiently opaque to protect the species even against the moderately intense incident UV radiation. The above results were unexpected from classical views of the [C II] emission, which was generally considered to trace intense interstellar UV radiation enhanced by active star formation.

• 한국산학기술학회논문지
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• 제9권6호
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• pp.1607-1613
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• 2008

마이크로 칼럼 기술을 응용한 초소형 자유전자 레이저 모듈의 특성을 연구하였다. 초소형 자유전자 레이저는 전자 방출원과 방사광 발생 장치로 나뉜다. 방사광 발생 장치는 위글러(wiggler)라 불리는데 그리드(grid) 판으로 구성되어 있다. 전자가 위글러를 지나갈 때 규칙적으로 배열된 그리드에 인가된 전압에 의하여 전자의 궤적이 사인(sinusoidal) 함수 모양으로 주기적으로 변하여 방사광을 발생시킨다. 본 연구에서는 초소형 자유전자 레이저 위글러의 매개 변수에 따른 전자빔 궤적을 전산모사를 이용하여 분석하였다. 쌍을 이루는 위글러 간격, 그리드의 폭, 깊이, 주기, 그리고 그리드에 인가된 전압이 전자빔에 미치는 효과를 조사하였다.

• 전기의세계
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• 제18권6호
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• pp.58-63
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• 1969

필자는 메이서와 레이서에 대하여 되돌고이면 평이하게 정성적으로 기술하려고 한다. "Maser"란 말은 Microwave Amplification by Stimulated Emission of Radiation. 또 "Laser"란 Light Amplification by Stimulated Emission of Radiation의 약자이다. 이 메이서나 레이서는 진공관 원리에서 사용되는 자유전자대신 원자의 구속전자를 사용하여 에너지를 발생하든가 증폭작용을 하고 있다. 자극방사 (Stimulated emission)란 말은 원자에서 에너지 방사가 있기 위해서는 구속전자에 자극을 줘야하기 때문에 생긴 것이다. microwave란 말을 붙인 것은 전자에너지중 이 주파수범위내에 해당되는것에만 이용된다는 것이고 이와 마찬가지로 광(light)은 전자복사중 이 빛의 파장범위에서 작용된다는 것을 말한다. 따라서 이 메이서나 레이서는 매우 높은 주파수 범위에서 사용되는 에너지 발생장치 또는 증폭기라고 생각할 수 있다. 이 메이서나 레이서의 동작원리는 진공관증폭기의 동작원리와 다르므로 따라서 그 동작원리를 이해하려면 새로운 개념이 필요하게된다. 과학기술의 발달과 함께 과거의 전자기긱의 성능은 그 한계에 도달하게 되었고 통신, 천문학, 의학, 산업, 과학연구분야등에서 이 메이서와 레이서는 새로운 기회와 가능성을 제시해주고 있다.운 기회와 가능성을 제시해주고 있다.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2003년도 International Meeting on Information Display
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• pp.752-755
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• 2003

An EMI emission of 42" AC-PDP panel is studied in this paper. First, the EMI emission level is roughly estimated using both simple electric dipole type and magnetic dipole type radiator model. The value of current required for estimation has been obtained from Fourier Transform of the measured current in time domain. Second, we investigate which type of EMI radiation is dominant by FEM calculation of the wave impedance. The result shows that electric dipole type radiation is dominant EMI source.

• 천문학회보
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• 제35권1호
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• pp.69.2-69.2
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• 2010

The far-ultraviolet (FUV) H2 and C IV emission images and spectra of Orion Eridanus Superbubble (OES) is hereby presented. The OES seems to consists of multiple phase through the detection of highly-ionized gas and pervasive neutral hydrogen. The former is traced by hot gas while the latter is traced by cold medium. A spectral image made with H2 fluorescent emission shows that the spatial distribution of hydrogen molecule is well correlated with the dust map. The model spectra was taken from a photodissociation region (PDR) radiation code which find a best suitable parameter such as hydrogen density, gas temperature and incident uv intensity of the radiation field. C IV emission is caused by intermediate temperature ISM about 10^4.5 K~10^6 K. Therefore we could get more clear evidence to reveal the structure of OES. Feature of spectra for the each sub region is also presented and discussed. The data were obtained with the Far-Ultraviolet Imaging Spectrograph (FIMS) and the whole data handling were followed by previous FIMS analysis.

• 천문학회보
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• 제35권2호
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• pp.71.1-71.1
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• 2010

The far-ultraviolet (FUV) C IV and H2 emission spectra of Orion-Eridanus Superbubble (OES) is hereby presented. The OES seems to consist of multiple phase through the detection of highly-ionized gas and pervasive neutral hydrogen. The former is traced by hot gas while the latter is traced by cold medium. A spectral image made with H2 fluorescent emission shows that the spatial distribution of hydrogen molecule is well correlated with the dust map. The model spectra was taken from a photodissociation region (PDR) radiation code which finds a best suitable parameter such as hydrogen density and intensity of the radiation field. C IV emission is caused by intermediate temperature ISM about 10^5 K. Therefore we could get more clear evidence to reveal the morphology of OES. In this process, the hydrogen density and gas temperature were also estimated. The data were obtained with the Far-Ultraviolet Imaging Spectrograph (FIMS) and the whole data handling were followed by previous FIMS analysis.

• Journal of Astronomy and Space Sciences
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• 제33권3호
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• pp.147-166
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• 2016

A radio-quiet γ-ray pulsar is a neutron star that has significant γ-ray pulsation but without observed radio emission or only limited emission detected by high sensitivity radio surveys. The launch of the Fermi spacecraft in 2008 opened a new epoch to study the population of these pulsars. In the 2^nd Fermi Large Area Telescope catalog of γ-ray pulsars, there are 35 (30 % of the 117 pulsars in the catalog) known samples classified as radio-quiet γ-ray pulsars with radio flux density (S₁₄₀₀) of less than 30 μJy. Accompanying the observations obtained in various wavelengths, astronomers not only have the opportunity to study the emitting nature of radio-quiet γ-ray pulsars but also have proposed different models to explain their radiation mechanism. This article will review the history of the discovery, the emission properties, and the previous efforts to study pulsars in this population. Some particular cases known as Geminga-like pulsars (e.g., PSR J0633+1746, PSR J0007+7303, PSR J2021+4026, and so on) are also specified to discuss their common and specific features.

• 천문학회보
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• 제40권1호
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• pp.86.3-86.3
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• 2015

There could be significant numbers of isolated stellar mass black holes in our Galaxy. The detection of these black holes will provide important clues on the origin of supermassive black holes. Interstellar gas will be accreted to these isolated black holes in nearly spherical flow. The gas and the interstellar magnetic field will be compressed and emit bremsstrahlung and magnetic bremsstrahlung. We calculate the density, temperature, magnetic field of the accretion flow onto a 10 solar mass black hole as well as its radiative emission; special attention is given to cyclotron radiation and synchrotron radiation, which covers from microwave to X-ray. We consider the possibility to detect these radiation from isolated Galactic black holes with current instruments and surveys.