• Journal of the Korean Vacuum Society
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• v.21 no.1
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• pp.62-68
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• 2012

The conversion efficiency of solar cells depending on incident angle of light is important for building-integrated photovoltaics (BIPV) applications. The quantum efficiency is the ratio of the number of charge carriers collected by the solar cell to the number of photons of a given energy shining on the solar cell. The analysis of angle dependence of quantum efficiencies give more information upon the variation of power output of a solar cell by the incident angle of light. The variations in power output of solar cells with increasing angle of incidence is different for the type of cell structures. In this study we present the results of the quantum efficiency measurement of single-crystalline silicon solar cells and a-Si:H thin-film solar cells with the angle of incidence of light. As a result, as the angle of incidence increases in single-crystalline silicon solar cells, quantum efficiency at all wavelength (300~1,100 nm) of light were reduced. But in case of a-Si:H thin-film solar cells, quantum efficiency was increased or maintained at the angle of incidence from 0 degree to about 40 degrees and dramatically decrease at more than 40 degrees in the range of visible light. This results of quantum efficiency with increasing incident angle were caused by haze and interference effects in thin-film structure. Thus, the structural optimization considering incident angle dependence of solar cells is expected to benefit BIPV.

• The Bulletin of The Korean Astronomical Society
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• v.35 no.1
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• pp.32.2-32.2
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• 2010

The Korean Solar Radio Burst Locator (KSRBL) is a single dish radio spectrograph, which is designed to record the spectra of microwave (0.5 - 18 GHz) bursts with 1 MHz spectral resolution and 1 s time cadence, and locate their positions on the solar disk within 2 arcmin. It was installed at KASI in 2009 August, and operational thereafter. The antenna pointing coefficients were initially determined during the installation and refined later using a series of antenna pointing calibrations. The filter to prevent the radio frequency interference around 2 GHz was designed and is to be installed. After the installation, the full frequency coverage will be recovered from the temporarily restricted frequency coverage (5 - 14 GHz). Also an effort to solve a couple of minor problems for the full performance of the system is in progress.

• The Transactions of the Korean Institute of Power Electronics
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• v.25 no.2
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• pp.118-126
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• 2020

A solar array simulator is a special power supply that regulates the output voltage and current to simulate the characteristics of a photovoltaic panel. The operating point of the panel is difficult to control with a single controller because of the non-linearity of the output curve, which is determined by the amount of irradiation, temperature, and panel material. In the conventional method, the output curve is divided into sections through the current and the voltage mode controls. It reduces the overall performance of the system due to the interchanging control mode. By using the single mode controller, the noise interference of the measured value and the stability of the control around the maximum power point were demonstrated. To solve these issues, this study proposes a new unified controller. The stability of the controller was analyzed along with operating principles, and performance improvement was experimentally verified.

• 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 Advanced Navigation Technology
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• v.27 no.6
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• pp.798-803
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• 2023

In the industrial internet of things (IIoT) industry, including smart factories, there are many cases where electronic devices are complexly combined and installed due to the recent development of intelligent information technology. Electromagnetic waves generated from such complex facilities affect other devices and services, which can lead to safety issues. The problem such as electromagnetic interference (EMI) and electromagnetic compatibility (EMC) generated when controlling complex facilities is an essential element that must be solved, and the engineering basis for EMI and EMC must be established to foster the industry of complex facilities. Therefore, in this study, EMC & EMI engineering demonstration cases for solar power fixed facilities using the national standard guideline have been analyzed. The results show that the electromagnetic risk indices in the solar power facilities have been degraded up to control level, and a national EMC engineering system has been proposed for complex facilities.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.480.1-480.1
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• 2014

In this study, we suggest the new emitter formation applied solid phase epitaxy (SPE) growth process using rapid thermal process (RTP). Preferentially, we describe the SPE growth of intrinsic a-Si thin film through RTP heat treatment by radio-frequency plasma-enhanced chemical vapor deposition (RF-PECVD). Phase transition of intrinsic a-Si thin films were taken place under $600^{\circ}C$ for 5 min annealing condition measured by spectroscopic ellipsometer (SE) applied to effective medium approximation (EMA). We confirmed the SPE growth using high resolution transmission electron microscope (HR-TEM) analysis. Similarly, phase transition of P doped a-Si thin films were arisen $700^{\circ}C$ for 1 min, however, crystallinity is lower than intrinsic a-Si thin films. It is referable to the interference of the dopant. Based on this, we fabricated 16.7% solar cell to apply emitter layer formed SPE growth of P doped a-Si thin films using RTP. We considered that is a relative short process time compare to make the phosphorus emitter such as diffusion using furnace. Also, it is causing process simplification that can be omitted phosphorus silicate glass (PSG) removal and edge isolation process.

• Journal of the Optical Society of Korea
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• v.20 no.6
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• pp.784-793
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• 2016

We present a single shot low coherence white light Hilbert phase microscopy (WL-HPM) for quantitative phase imaging of Si optoelectronic devices, i.e., Si integrated circuits (Si-ICs) and Si solar cells. White light interferograms were recorded by a color CCD camera and the interferogram is decomposed into the three colors red, green and blue. Spatial carrier frequency of the WL interferogram was increased sufficiently by means of introducing a tilt in the interferometer. Hilbert transform fringe analysis was used to reconstruct the phase map for red, green and blue colors from the single interferogram. 3D step height map of Si-ICs and Si solar cells was reconstructed at multiple wavelengths from a single interferogram. Experimental results were compared with Atomic Force Microscopy and they were found to be close to each other. The present technique is non-contact, full-field and fast for the determination of surface roughness variation and morphological features of the objects at multiple wavelengths.

• Journal of the Korean Solar Energy Society
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• v.34 no.3
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• pp.66-74
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• 2014

In this paper, the performance of Hybrid Dimming control system for Daylighting system is evaluated by accredited tests. The system controls the balance of illuminance of daylight between daylight system and LED light system. It makes the normal illuminance of interior without the effects of weather by controlling the LED depending on the brightness of outside. For the tests, 6 diffusers($600{\times}300mm$) were installed in lighting area($36m^2$) and normal operation of the system sensors were tested about the interference of sunlight. The results of the examinations were satisfied with the criteria of accredited tests. Further research is the verification of energy saving effect by comparing the Hybrid Dimming control system to current artificial light system.

• Journal of the Korean Solar Energy Society
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• v.28 no.5
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• pp.56-64
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• 2008

The objective of this study is to develope ground heat exchanger using PHC file used to building foundation, and it's element technology. So we construct PHC ground heat exchanger in the apartment house's PHC foundation and evaluate it's performance. First, we study PHC file type, heat exchanger pipe, grouting materials, and present apartment house's foundation condition for PHC ground heat exchanger and design it's proto type. Second according to grouting materials, we estimate construction convenience, and it's performance. Construction convenience side, PB 22 A pipe and sand grouting with moisture was good for PHC ground heat exchanger elements. Experiment result is very superior. Thermal conductivity B, C type(sand, gravel) was respectively 32.4 W/m$^{\circ}C$, 36.5 W/m$^{\circ}C$, D(concrete) Type 27.8 W/m$^{\circ}C$, E(bentonite) Type 19.6 W/m$^{\circ}C$. Thermal interference for 4 day experiment period in 3.8 m was very small. So PHC file is good for using ground heat exchanger.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.26 no.9
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• pp.821-827
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• 2015

Electromagnetic waves which are emitted from the Sun due to solar flare explosion can cause failures in HF radio communications in the day-side area of the Earth, that is so-call as Radio Blackouts. The international scale representing the severity of the Radio Blackouts is determined by the solar X-ray flux which is measured by United States Geostationary Operational Environmental Satellite. However, the scale is not always applicable to HF communication users in the different area on the Earth, because the HF communication effects depend not only on the X-ray strength but also on the subsolar point location. To solve this problem, we developed a HF radio spectrum monitoring system utilizing a spectrum analyzer. This system conducts a real-time measure of the HF spectrum, and automatically calculates signal to noise ratios and the occurrences of the HF blackouts as comparing with the interference level which is described from the ITU recommendation.