• Journal of the Korean Society for Aviation and Aeronautics
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• v.24 no.1
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• pp.25-32
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• 2016

This study deals with the light environments and weather conditions affecting to the night illuminance over the Korean peninsula. The experiment was executed to analyze the effects on the illuminance at separate sites(Gyeryong and Pilseung) considering the different light environments. The analysis was applied to illuminance measurement from the lightmeter, which was developed for the IYA(International Year of Astronomy) 2009, in order to observe the illuminance of areal networks. The weather observations, such as the cloud cover and visibility, were used to understand the quantitative influence of the illuminance to the selected sites. The results show that the illuminance measurements are significantly different from data of the operational illuminance prediction model which simply applies extinction effect for the illuminance. It shows that these differences are caused by the light environments and weather conditions for each site. Therefore, it can be confirmed that the night illuminance is the output of interaction with the characteristics of light for luminous sources.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.50 no.9
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• pp.444-449
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• 2001

In this paper, a novel ultraviolet sensor is presented based on a photoluminescent porous silicon. Porous silicon layer was formed by chemical etching of surface of pn junction in a $HF(48%)-HNO_3(60%)-H_20$ solution. Incident ultraviolet(UV) light is converted to visible light by photoluminescent porous silicon layer, and then this visible light generates electron-hole pairs in the pn junction, which produces a photocurrent flow through the device. In order to maximize detection efficiency, the peak sensitivity wavelength of the pn junction diode was matched with the peak wavelength of Photoluminescence from porous silicon layer. The porous silicon ultraviolet sensor showed a large output current as UV intensity increases and but very low sensitivity to visible light. The detection sensitivity of porous silicon sensor was calculated as 2.91mA/mW. These results are expected to open up a possibility that the present porous silicon sensor can be used for detecting UV light in a visible background, compared to silicon UV detectors which have an undesirable response to visible light.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.26 no.2
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• pp.158-163
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• 2013

In this paper, thermal analysis of heatsink for 30 W class Chip-on-Board (COB) LED light source is performed by using SolidWorks Flow Simulation package. In order to increase the convection heat transfer, number of fin and shape of the heatsink is optimized. Furthermore, a copper spread is applied between the COB LED light source and the heatsink to mitigate the heat concentration on the heatsink. With the copper spread, the junction temperature between the COB LED light source and the heatsink is $50.9^{\circ}C$, which is $5.4^{\circ}C$ lower than the heatsink without the copper spread. Due to the improvement of the junction temperature, the light output is improved by 5.8% when the LED light source is stabilized. The temperature difference between the simulation and measured result of the heatsink with the copper spread is within $2^{\circ}C$, which verifies the validity of the thermal design method using a simulation package.

• Nuclear Engineering and Technology
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• v.55 no.3
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• pp.1045-1051
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• 2023

In this study, we fabricated a liquid light-guide-based radiation sensor with a LaBr₃:Ce scintillator for remote gamma-ray spectroscopy. We acquired the energy spectra of Cs-137 and Co-60 using the proposed sensor, estimated the energy resolutions of the full energy peaks, and compared the scintillation light output variations. The major peaks of the radionuclides were observed in each result, and the estimated energy resolutions were similar to that of a general NaI(Tl) scintillation detector without a liquid light guide. Moreover, we showed the relationships of energy resolution and analog-to-digital channel regarding the number of photoelectrons produced and confirmed the effects of light guide length on remote gamma-ray spectroscopy. The proposed sensor is expected to be utilized to perform remote gamma-ray spectroscopy for distances of 3 m or more and would find application in many fields of nuclear facilities and industry.

• Journal of Sensor Science and Technology
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• v.27 no.5
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• pp.294-299
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• 2018

This article describes the output properties of non-dispersive infrared carbon dioxide($CO_2$) sensors resulting from the changes in ambient temperatures. After the developed sensor module was installed inside the gas chamber, the temperature was set to 267 K, 277 K, 300 K, and 314 K, and the concentrations of $CO_2$ gas were increased from 0 to 5,000 ppm. Then, the output voltage at each concentration was obtained. Through these experimental results, two observations were made. First, both the $CO_2$ sensor and the reference sensor showed an increase in the output voltages as the temperature rose from 0 ppm, Second, the full scale outputs of the $CO_2$ sensor grew as the temperature increased. The output characteristics were analyzed based on two factors: change in the radiant energy of the infrared light source and change in the absorptivity of $CO_2$ gas according to the ambient temperature. Additionally, temperature compensation methods were discussed.

• Proceedings of the KIEE Conference
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• 1996.07c
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• pp.1421-1423
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• 1996

In this study, the effect of solar cell cover glass on the solar cell performance is evaluated. Silicon solar cell (active area:4*6cm, efficiency:12.6% at AMO condition) is used for this study. ITO(Indium tin Oxide) film thickness of the ITO/AR/substrate glass/solar cell structure samples are $40{\AA}$, $60{\AA}$, $160{\AA}$, $240{\AA}$ respectively. The solar cell maximum output power on the stacking structure variations showed 465mW in the AR/ITO/substrate glass/solar cell, and minimum output power showed 403mW in the AR/substrate glass/solar cell. The maximum output power of the solar cell on the ITO thickness variations of the ITO/AR/substrate glass/solar cell showed 460mW at $40{\AA}$ then decrease output power as ITO thickness increase. For environment tests, all samples are exposed UV light in the vacuum chanber. The output power degradation of AR(UVR)/substrate glass/solar cell stacking structure is small compared with ITO/AR(UVR)/substrate glass/solar cell stacking structure.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.1871-1875
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• 2003

The cancellation of the output signal occur between output tubs have occurred place an electromagnetic interference and deteriorated the light efficiency of the neon tub. In order to prevent this problems, we have developed the modified electronic ballast for neon(MEBN). The MEBN have used a shielded line to the output and designated partly the half-bridge in the middle of the circuit. In an experimental results, this will be lengthen the life of the neon tub and obtain the effect which shields an electromagnetic wave to injurious to the people’s body.

• Korean Journal of Optics and Photonics
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• v.7 no.3
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• pp.244-249
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• 1996

Multipass Ti:sapphire amplifier for the light source of DIAL was developed with an angular-multi-plexing, and the characteristics of output energy and spectra were investigated. As the characteristics of two-stage multipass amplifier, the maximum output energy was 22 mJ and the amplification gain was 20 dB on the wavelength of 790 nm. At that condition, output efficiency of the pumping energy was 18 percent. We obtained $0.15cm^{-1}$ (9.4 pm) as a spectral linewidth in the tuning range of 705~845 nm.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.22 no.3
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• pp.193-198
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• 2009

Recently, characteristic research by the changes in the spectrum, one of the factors that influence analysis of maximum output power of PV module, has been studied. In this paper, a one-day intensity of solar irradiation, change of spectrums with time and electrical output for spectrums are analyzed. As a result, blue-rich wavelength compared with red-rich wavelength has large variation of solar irradiance with time, so we recognized that change of solar irradiance is dominated by variation of blue~rich wavelength. Also in same intensity of solar irradiance, electrical output in blue-rich wavelength was 3-8 % higher than one in red-rich wavelength.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.2
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• pp.361-366
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• 2007

In the distribution networks, it is necessary to develop small and light voltage and current sensor for compact and digitalized switchgears. For this purpose, some researches have been continuing till now, CT(current transformer) and VT(voltage transformer) are one of that research. But conventional CT and VT have some problems, that is, have big size and saturation characteristics because of used to iron core. In this paper, CS(current sensor) and VS(voltage sensor), have some merits measuring of current and voltage magnitude as a alternated conventional equipment, were studied. So, this paper shows the process CS and VS design method, equivalent circuit and output result, respectively. As a result of this test, proposed CS and VS have linearity for the output, no saturation.