• Journal of The Korean Astronomical Society
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• v.32 no.1
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• pp.65-73
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• 1999

In this study we present a new improved nonlinear calibration method for vector magnetograms made by the Solar Flare Telescope of BOAO. To identify Fe I 6302.5 line, we have scanned monochromatic images of the line integrated over filter passband, changing the location of the central transmission wavelength of a Lyot filter. Then we obtained a filter-convolved line profile, which is in good agreement with spectral atlas data provided by the Sacramento Peak Solar Observatory. The line profile has been used to derive calibration coefficients of longitudinal and transverse fields, employing the conventional line slope method under the weak field approximation. Our improved nonlinear calibration method has also been used to calculate theoretical Stokes polarization signals with various angles of inclination of magnetic fields. For its numerical test, we have compared input magnetic fields with the calibrated ones, which have been derived from the new improved non-linear method and the conventional method respectively. The numerical test shows that the calibrated fields obtained from the improved method are consistent with the input fields, but not with those from the conventional method. Finally, we applied our new improved method to a dipole model which characterizes a typical field configuration of a single, round sunspot. It is noted that the conventional method remarkably underestimates the transverse field component near the inner penumbra.

• Current Optics and Photonics
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• v.5 no.3
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• pp.220-228
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• 2021

To improve the measurement accuracy of a solar-radiation observer instrument, aiming at the problem of multiorder-stray-light interference caused by the diffraction of the flat-field concave grating in the spectroscopic system, straylight suppression methods for different forms of optical traps are studied. According to the grating surface-scattering distribution-function model, the bidirectional scattering distribution function (BSDF) of a dust-polluted surface and the flat-field concave grating's transition area of the spectroscopic system is calculated, and a Lyot stop with blade baffle is designed to suppress this kind of stray light. For diffraction multiorder stray light, based on the theory of light-energy transmission, a design for precise positioning of the trench optical trap is proposed. The superiority of the method is verified through simulation and actual measurement. The simulation results show that in a spectroscopic system approximately 160 mm × 140 mm × 80 mm in size, the energy of the stray light is reduced by one order of magnitude by means of the trench optical trap and Lyot stop, and the number of beams is reduced from 5664 to 1040. The actual measurements show that the stray-light-suppression efficiency is about 69.4%, which is effective reduction of the amount of stray light.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.11 no.3
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• pp.166-173
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• 2012

This study is about comparison of thermal and flow characteristics on the wind & radiant heat shield with STS mesh type screen for offshore. Numerical analysis was conducted to find transmission coefficient in the mesh and then analyse the flow characteristics about wind & radiant heat shield. The experiment method of solar radiation has been used as thermal radiation source to get the performance of radiant heat shield measurement. The sensor radiation device has been used to measure the reduction of solar radiation with various size of cells and at a distance of 0.5m and 1m from the cold face of the wind & radiant heat shield.

• Journal of the Korean Solar Energy Society
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• v.40 no.1
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• pp.35-47
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• 2020

Due to the large window area, the lighting environment of the educational space between the window and deep part of the room is not uniformly illuminated, and the phenomenon of glare is severe. For this reason, the daylight performance of DSC-BIPV windows was analyzed in order to improve the natural lighting in the educational sector. The method derives the correlation with natural lighting by measurement and simulation. Dynamic simulation confirmed that the average illuminance of the target space was higher at later than the early afternoon. The performance of natural lighting at 40% and 30% transmission of DSC has the effect of significantly reducing the amount of excess light in existing windows. Nevertheless, the actual average illuminance in all seasons corresponds to the standard illuminance of the educational facility, 300 Lux. In addition, the uniformity is also seen through the skylight illuminance ratio.

• Proceedings of the KIEE Conference
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• 2003.07a
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• pp.442-444
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• 2003

For the safety of aircraft, aviation obstacle lights must be attached to the transmission towers in accordance with the governing law. Aviation obstacle lights which consist of solar cells, batteries. xenon lamps and a regulator substituted for aviation obstacle lights using AC power. A xenon lamp has advantage such as high brightness but also has disadvantage like large power consumption which cause lighting system to have many solar cells and batteries. This paper introduces an application of a aviation obstacle light using LED lamp through the economic analysis between LED lamp and xenon lamp.

• The Journal of the Korea institute of electronic communication sciences
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• v.16 no.4
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• pp.605-610
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• 2021

Wireless charging method using a laser is considered as the most efficient method at a long distance of the wireless charging method. Combining long-range laser wireless charging technology with wireless communication technology will make it possible to use it for a variety of applications. Accordingly, this paper shows the results of research and experiments on wireless charging and wireless communication simultaneously based on a laser. This technique uses a laser as a light source for E/O(: Electric-to-Optical) conversion at the transmitter for optical wireless power transmission. In the experimental results, the optical power transmission using a 100 mW laser transmitter and a solar cells receiver showed a DC-to-DC efficiency of 1.9 %, wireless optical communication showed a transmission speed of up to 90 kbps when the transmission distance is 15 m.

• Journal of the Microelectronics and Packaging Society
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• v.23 no.3
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• pp.57-61
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• 2016

In order to protect the solar cells from the moisture and oxygen, we evaluated the electrical and optical properties for the $Cu(In,Ga)Se_2$ (CIGS) solar cells which were prepared by the spray coating method. Generally, the EVA (ethylene-vinyl acetate) films are laminated to protect the CIGS flexible solar cells, which results in a high cost process due to complicated devices. In this study, we tried to prepare the protection layers of the flexible CIGS flexible solar cells by using spray coating method instead of conventional laminating films in order to reduce the device weight as well as the process time. The CIGS solar cells with spray coating method showed an enhanced efficiency than the before treated sample (2.77% to 2.93%) and relatively proper water vapor transmission rate of the solar cells about 62.891 gm/[$m^2-day$].

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.21 no.4
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• pp.582-587
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• 2012

Recently, the low-emissivity glass has been used to reduce the energy loss through building windows. However, it simply reduces the inflow of solar rays and has a relatively high heat transmission coefficient. To solve the problems, a high-efficiency vacuum glazing has been under development but it has not been actively used due to its high price and insufficient performance. In this paper, the effects of internal pressure, pillar (spacer) height, pillar diameter, pillar interval, emissivity etc. on the performance of vacuum glazing have been analyzed with three-dimensional computational fluid dynamics and structural analysis. As a result, the performance of vacuum glazing was predicted more accurately and major factors that determine the performance of vacuum glazing were optimized.

• Journal of the Korean Ceramic Society
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• v.29 no.1
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• pp.48-52
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• 1992

Indium tin oxide (ITO) layers are of considerable interest on account of the combination of properties they provide high electrical conductivity, high infrared reflection with high solar energy transmission, high transmission in the visible range. We are concerned about the variation of the spectral transmittances and sheet resistances as the thickness of SiO2-ZrO2 barrier layer and ITO layers and heat treating conditions are changed. Transmittances and reflectivities were studied by measuring UV-VIS-NIR-, FT-IR spectroscopy. ITO films are crack free, homogeneous and of polycrystalline cubic structure. The microstructure of good ITO films shows a narrow grain size distribution and mean value of 100 nm. The selectivity of absorbing properties is improved by increasing the thickness of ITO films. The increase of sheet resistance of ITO films are due to the increase in the reaction between films and glass substrate.

• Journal of Advanced Marine Engineering and Technology
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• v.30 no.2
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• pp.267-274
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• 2006

There are no solar loads through windows and heat transfer from outer walls of the building to the interior This study analyzes indoor air temperature and air flow distribution for the interior of buildings or vessels occupying space. Numerical method is adopted to visualize the indoor side environmental situation. that is without heat transmission to outside the building in various cooling load conditions; supply ventilation lighting. occupancy and infiltration in conditioned spaces. Reaching time of an air conditioner is predicted theoretically by cooling load variations. Theoretical modelling of the reaching time shows good agreement with experimental results.