• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제43회 하계 정기 학술대회 초록집
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• pp.272-272
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• 2012

Additional neutral particle analyzer has been installed to investigate the variation of fast ion tails with regard to the line of sight during 2012 KSTAR campaign. The system has the same photo-diode particle detector as previous system [1]. Both newly installed system and previous system modifield for 2012 campaign have two channels. One has a particle stopper transparent to hard X-ray, the other has no one. It will be used to separate the hard X-ray component from total hard X-ray and fast neutral counts. It is expected to measure fast ion tails more clearly through this extended system. A detailed system and calibration result will be presented in the conference.

• 천문학회지
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• 제29권spc1호
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• pp.291-294
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• 1996

The .Japanese sun observing satellite, Yohkoh, has been operational for five years and her scientific instruments are still in good condition. They have revealed ample of evidences that solar flares were triggered by magnetic reconnection, which was, for the first time, clearly indicated to take place in the solar corona. Cusp structures in soft X-rays and a new type of hard X-ray sources at the top of flaring loops have strongly supported the scenario originally proposed by C-S-H-KP. Nonthermal energy input in hard X-rays and thermal energy estimated from soft X-rays are fundamentally consistent with the interpretation of thick-target and chromospheric-evaporation models (Neupert effect). X-ray jets, another discovery of Yohkoh, were also associated with magnetic reconnection, as a result of the interaction of emerging fluxes with pre-existing coronal loops. Temperature structures of active regions, quiet sun, and coronal holes had very dynamic differential-emission-measure (DEM) distributions and high-temperature tails of DEM were considered to come from the contribution of flare-like activity.

• 대한방사선기술학회지:방사선기술과학
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• 제33권3호
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• pp.179-184
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• 2010

나노 공간분해능을 갖는 영상을 얻기 위한 경엑스선 현미경 시스템에서는 단색 엑스선이 요구된다. 엑스선관에서 발생되는 화이트 빔으로부터 8.4 keV의 텅스텐 $L_{\alpha}$ 특성방사선을 84% 이상 반사시킬 수 있는 5.65 nm의 단위막 두께를 가지는 C/W 다층박막 거울을 설계하였고, 이온빔 스파터링 장치를 이용하여 $50{\times}50\;mm$ 크기로 제작하였다. 제작된 C/W 다층박막 거울은 99.5% 이상의 균일도(Uniformity)를 가지며, TEM 사진을 이용해 그 구조를 확인하였다. 8.05 keV의 구리 특성방사선을 광원으로 하는 엑스선 반사율 측정 장치를 이용한 다층박막 거울의 반사율을 측정함으로써 C/W 다층박막 거울의 8.4 keV에서의 반사율을 예상할 수 있었다. 제작된 C/W 다층박막 거울과 엑스선관을 이용하여 8.4 keV의 특성방사선을 획득함으로써 단색 엑스선을 획득하였다. 이때의 반사율은 77.1%였고, 단색 엑스선의 반치폭은 0.21 keV이었다. 엑스선관에서 높은 효율로 단색 엑스선을 획득할 수 있어 실험실 규모의 경엑스선 현미경 장치의 광원으로써 사용될 수 있는 가능성을 확인하였고, 다층박막 거울의 단위막 두께를 수 나노미터로 제작한다면 17.5 keV의 몰리브덴 특성방사선에 해당하는 단색 엑스선을 얻어 유방촬영에도 적용할 수 있을 것이다.

• 천문학논총
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• 제30권2호
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• pp.565-568
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• 2015

In this work, we study the correlation between the photon index (${\Gamma}$) of the X-ray spectrum and the 2-10 keV X-ray luminosity ($L_X$) for black hole X-ray binaries (BHBs). The BHB sample is mainly from the quiescent, hard and intermediate states, with values of $L_X$ ranging from ${\sim}10^{30.5}$ to $10^{37.5}$ erg $s^{-1}$. We find that the photon index ${\Gamma}$ is positively or negatively correlated with the X-ray luminosity $L_X$, for $L_X$ above or below a critical value, ${\sim}10^{36.5}$ erg $s^{-1}$. This result is consistent with previous works. Moreover, when $L_X{\leq}{\sim}10^{33}$ erg $s^{-1}$, we found that the photon index is roughly independent of the X-ray luminosity. We interpret the above correlations in the framework of a coupled hot accretion flow - jet model. Besides, we also find that in the moderate-luminosity region, different sources may have different anti-correlation slopes, and we argue this diversity is caused by the different value of ${\delta}$, which describes the fraction of turbulent dissipation that directly heats electrons.

• 진공이야기
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• 제3권4호
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• pp.4-7
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• 2016

An X-ray Free Electron laser facility (PAL-XFEL) has been built in Pohang Accelerator Laboratory to provide X-ray FEL radiations for photon users. The machine consists of a 10 GeV normalconducting S-band linear accelerator and two undulator beamlines. The hard and soft X-ray beamlines will provide FEL radiations with wavelengths of 0.6 to 0.1 nm and 4.5 to 1 nm, respectively. Beam commissioning of PAL-XFEL is ongoing and user service will start in 2017. In this report, the PAL-XFEL layout and the working principle are discussed.

• 천문학논총
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• 제27권4호
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• pp.285-286
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• 2012

We combine data from two all-sky surveys, the Swift/Burst Alert Telescope 22 Month Source Catalog and the AKARI Point Source Catalogue, in order to study the connection between the hard X-ray (> 10 keV) and infrared (IR) properties of local active galactic nuclei (AGN). We find two photometric diagnostics are useful for source classification: one is the X-ray luminosity vs. IR color diagram, in which type 1 radio-loud AGN are well isolated from other AGN. The second one uses the X-ray vs. IR color-color diagram as a redshift-independent indicator for identifying Compton-thick (CT) AGN. Importantly, CT AGN and starburst galaxies in composite systems can also be separated in this plane based upon their hard X-ray fluxes and dust temperatures. This diagram may be useful as a new indicator to classify objects in new surveys such as with WISE and NuSTAR.

• 한국광학회:학술대회논문집
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• 한국광학회 2005년도 하계학술발표회
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• pp.60-61
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• 2005

Polycapillary optics are fabricated for hard X-ray waveguide. The Calculation of propagation conditions in polycapillary are conducted to obtain the focal length and spot size as well as the demension of the polycapillary optic devices. X-ray energy of 8 KeV is propagated in the polycapillary optics which the exit diameter of 2.3 mm. and 17 mm in length.

• 천문학논총
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• 제30권2호
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• pp.417-421
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• 2015

We analyzed 0.5-45 keV data of NGC 3227 observed by Suzaku six times between 2008 October 28 and December 2. The count-count plot between the 0.5-3 keV and 3-10 keV bands exhibits a clear break, separating the data into bright and faint phases. Applying the difference spectrum method and time-averaged spectral fits to the phase data, we found the presence of two kinds of variable primary X-rays, (1) a hard primary component with ${\Gamma}{\sim}1.7$ dominating in the faint phase and (2) a soft primary continuum with ${\Gamma}{\sim}2.4$ appearing in the bright phase, both affected by partial absorption. Considering their timing and spectral characteristics, component (1) is presumably identical to a Compton continuum in the low/hard state, while component (2) may correspond to the hard tail emission in the high/soft state, or compact-jet emission. In that case, an accretion ow onto the central super massive black hole in NGC 3227 can be interpreted to include the two different states.

• 천문학회지
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• 제41권2호
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• pp.17-22
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• 2008

We present an analysis of the soft X-ray emission of MRK 841 to investigate its long-term variation. The light variation of MRK 841 for three different energy bands of soft, medium, and hard values were studied. The maximum variability with a factor of 5 for about two years was confirmed at all three different bands. The light curves exhibit a gradual variation of brightness. In addition to a gradual variation, the short- term or micro variation was also confirmed with a factor of about two for all three different bands. The light variation of each band did not exhibit a correlation between them, but the flare event is strongest in the soft band. The hardness ratio for hard and soft bands shows irregular variation but there was no correlation between them. It was confirmed that there is a gradual decrease of the photon index. Results of our analysis are discussed within the framework of the accretion disk phenomenon.

• 천문학회보
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• 제44권1호
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• pp.74.1-74.1
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• 2019

We present an ongoing imaging survey of the host galaxies of hard X-ray-selected active galactic nuclei (AGNs) observed with the Hubble Space Telescope (HST). The snapshot images are taken with the Advanced Camera for Surveys through an HST gap-filler program. The sample, selected from the 70-month Swift-BAT X-ray source catalog, represents an unbiased and uniform AGN population, which will enable us to test the AGN unification model and explore the physical connection between host galaxies and central supermassive black holes. We also plan to investigate the AGN triggering mechanism by examining merger signatures and searching for dual nuclei. We present the pipeline for imaging analysis and the current status of the survey.