• 천문학회보
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• 제43권2호
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• pp.46.1-46.1
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• 2018

The Fast Imaging Solar Spectrograph (FISS) on the Goode Solar Telescope (GST) at Big Bear Solar Observatory is the imaging Echelle spectrograph developed by the Solar Astronomy Group of Seoul National University and the Solar and Space Weather Group of Korea Astronomy and Space Science Institute. The instrument takes spectral data from a region on the Sun in two spectral bands simultaneously. The imaging is done by the organization of intensity data obtained from the fast raster scan of the slit over the field of view. Since the scan repeats many times, the whole set of data can be used to construct the movies of monochromatic intensity at arbitrary wavelengths within the spectral bands, and those of line-of-sight velocity inferred from different spectral lines. So far there are two standard observing configurations: one recording the $H{\alpha}$ line and the Ca II 8542 line simultaneously, and the other recording the Na I D2 line and Fe I 5435 line simultaneously. We have developed the procedures to produce the standard data for each observing configuration. The procedures include the spatial alignment, the correction of spectral shift of instrumental origin, and the lambdameter measurement of the line wavelength. The standard data include the movie of continuum intensity, the movies of intensity and velocity inferred from a chromospheric spectral line, the movies of intensity and velocity inferred from a photospheric line. The processed standard data will be freely available online (fiss.snu.ac.kr) to be used for research and public outreach. Moreover, the IDL procedures will be provided on request as well so that each researcher can adapt the programs for their own research.

• 천문학회보
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• 제40권1호
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• pp.84.3-85
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• 2015

We report a small-scale EUV bright loop associated with the evolution of the fine-scale magnetic discontinuity in the photosphere. Our analysis was carried out by using the high spatial resolution data taken with InfraRed Imaging Magnetograph (IRIM) and the Fast Imaging Solar Spectrograph (FISS). As a result, an extremely narrow dark lane of the intense horizontal magnetic field (width ~ 300 km) is detected parallel to the boundary of the magnetic pore, which is one of the footpoints of the small-scale bright coronal loop. We find that the variation of the net linear polarization inside the dark lane is closely related to the intensity variations of the coronal loop. Based on our results, we suggest that small-scale atmospheric heating such as bright coronal loop seen above the complex pore group may be strongly affected by the evolution of the fine-scale magnetic discontinuity in the photosphere. This is a nice example of solar atmospheric heatings associated with the fine-scale magnetic discontinuity in the photosphere.

• Current Photovoltaic Research
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• 제11권4호
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• pp.103-107
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• 2023

A Nickel oxide (NiO_x) thin films were prepared via sol-gel process on a transparent conductive oxide glass substrate. The NiO_x thin films were spin-coated in ambient air and subsequently annealed for 30 minutes at temperatures ranging from 150℃ to 450℃. The structural and optical characteristics of the NiO_x thin films annealed at various temperatures were measured using X-ray diffraction, field emission scanning electron microscopy, and ultraviolet-visible spectroscopy. After optimizing the NiO_x coating conditions, perovskite solar cells were fabricated with p-i-n inverted structure, and its photovoltaic performance was evaluated. NiO_x thin films annealed at 350℃ exhibited the most favorable characteristics as a hole transport layer, resulting in the highest power conversion efficiency of 17.88 % when fabricating inverted perovskite solar cells using this film.

• 천문학회보
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• 제45권1호
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• pp.44.4-45
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• 2020

The solar chromosphere can be observed well through strong absorption lines. We infer the physical parameters of chromospheric plasmas from these lines using a multilayer spectral inversion. This is a new technique of spectral inversion. We assume that the atmosphere consists of a finite number of layers. In each layer the absorption profile is constant and the source function is allowed to vary with optical depth. Specifically, we consider a three-layer model of radiative transfer where the lowest layer is identified with the photosphere and the two upper layers are identified with the chromosphere. This three-layer model is fully specified by 13 parameters. Four parameters can be fixed to prescribed values, and one parameter can be determined from the analysis of a satellite photospheric line. The remaining eight parameters are determined from a constrained least-squares fitting. We applied the multilayer spectral inversion to the spectral data of the Hα and the Ca II 854.21 nm lines taken in a quiet region by the Fast Imaging Solar Spectrograph (FISS) of the Goode Solar Telescope (GST). We find that our model successfully fits most of the observed profiles and produces regular maps of the model parameters. We conclude that our multilayer inversion is useful to infer chromospheric plasma parameters on the Sun.

• 한국진공학회지
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• 제16권3호
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• pp.167-171
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• 2007

세계적으로 석유자원의 고갈로 대체 에너지 중에서도 태양전지는 가장 주목받는 기술 중에 하나이며, 크게 무기물 태양전지와 유기태양전지로 구분된다. 그 중에서 유기태양전지의 변환효율은 무기물 태양전지에 상당히 미치지 못하지만, 제작공정의 비용이 낮고, 투명하고 다양한 색을 낼 수 있으며, 유연성을 띠는 장점으로 인하여 무기물 태양전지가 사용될 수 없는 시장을 중심으로 저비용 제품으로 사용될 가능성이 높아지고 있다. 현재 유기태양전지의 효율, 수명, 그리고, 안정성이 태양전지의 보급화에 중요한 이슈이며, 다양한 연구가 진행되고 있다. 본 글은 유기태양전지의 기술적 원리, 현재 개발 동향 및 이슈, 그리고 발전 방향에 대하여 정리하였다.

• Current Photovoltaic Research
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• 제2권3호
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• pp.120-123
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• 2014

Thermal doping method using furnace is generally used for solar-cell wafer doping. It takes a lot of time and high cost and use toxic gas. Generally selective emitter doping using laser, but laser is very high equipment and induce the wafer's structure damage. In this study, we apply atmospheric pressure plasma for solar-cell wafer doping. We fabricated that the atmospheric pressure plasma jet injected Ar gas is inputted a low frequency (1 kHz ~ 100 kHz). We used shallow doping wafers existing PSG (Phosphorus Silicate Glass) on the shallow doping CZ P-type wafer (120 ohm/square). SIMS (Secondary Ion Mass Spectroscopy) are used for measuring wafer doping depth and concentration of phosphorus. We check that wafer's surface is not changed after plasma doping and atmospheric pressure doping width is broaden by increase of plasma treatment time and current.

• 천문학회보
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• 제40권1호
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• pp.83.4-84
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• 2015

We report that a strong downflow event caused three-minute oscillations in the solar atmosphere. Our observations were carried out by using the Fast Imaging Solar Spectrograph (FISS) of the 1.6 meter New Solar Telescope (NST) and the Interface Region Imaging Spectrograph (IRIS). Our main findings are as follows: (1) The strong downflow was seen at the $H{\alpha}$ absorption line at first, and then appeared at the Si IV and C II emission lines. It seems that the characteristics of the downflow are consistent with a coronal rain event. (2) After the event, oscillations of velocity were identified in the chromospheric lines and transition region lines. (3) The amplitudes of oscillations were 2km/s at Mg II line and 3km/s at C II and Si IV lines and decreased with time. (4) The period of the oscillation was 2.67 minutes at first, but gradually increased with time. Our findings are in agreement with Chae & Goode (2015)'s theory that of acoustic waves generated by a disturbance in a gravitationally-stratified medium.

• 천문학회보
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• 제38권2호
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• pp.87.1-87.1
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• 2013

Ellerman bombs(EB) are small-scale bright features observed best in the wings of H alpha line. We used the Fast Imaging Solar Spectrograph(FISS) with the 1.6m New Solar Telescope at Big Bear Solar Observatory, in order to investigate characteristics of each EB. We analyzed H alpha line profiles of EBs, and classified EBs by their contrast profiles. To analyse characteristics of EBs, we applied power-law fitting ($C={\alpha}{\Delta}{\lambda}^{-n}$) to the EB contrast profiles. The amplitude ${\alpha}$ is a measure of the strength of an EB event (or the amount of released energy), and the power-law index n is a measure of spatial concentration of energy in the higher layers of the solar atmosphere. With the two parameters, we classified EBs into a few groups. We try to understand the physical properties of each group.

• 천문학회보
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• 제37권1호
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• pp.87.2-87.2
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• 2012

H${\alpha}$ transient bright kernels may be an important diagnostic of energy conversion processes occurring in the choromosphere during flares. We observed an H${\alpha}$ kernel that occurred in AR 11263 in associated with a small flare on 2011 Autust 5th using the Fast Imaging Solar Spectrograph installed at the 1.6m New Solar Telescope of Big Bear Solar Observatory. We find that both the H${\alpha}$ line and the CaII 8542${\AA}$ line appear in emission, with a red asymmetry in that they display red wings of enhanced emission. The red asymmetry shows 5-30 km/s downward motion for 8 minutes. We determine some physical parameters by adopting the Cloud mode and discuss the physical meaning of these results.

• 천문학회보
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• 제43권2호
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• pp.58.1-58.1
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• 2018

In the solar atmosphere, below the region of temperature minimum, temperature decreases with height and above it, temperature increases with height. Therefore the inference of temperature minimum is a basis of the study about the solar atmosphere and heating problem. The temperature of the temperature minimum region can be inferred from acoustic cutoff frequency. According to a recent study the acoustic cutoff frequency is related to the peak frequency of the power spectrum the chromospheric three-minute velocity oscillations. Using this relationship, we infer the temperature of temperature minimum. The three minute velocity oscillation and its power spectrum are obtained for a pore observed with the Fast Imaging Solar Spectrograph (FISS) $H{\alpha}$ band. We present the inferred temperature and compare it with the temperature of Maltby model. We also investigate the effect of the inclination of magnetic field on the temperature minimum.