• Korean Journal of Optics and Photonics
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• v.13 no.2
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• pp.128-133
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• 2002

In a recent effort to develop polymer light-emitting diodes (LEDs) as promising flat panel display components, measurements of reliable absolute photoluminescence (PL) and electroluminescence (EL) efficiency for polymer materials are required. In this work, we performed the measurement of PL and EL efficiency of luminescent polymers using an integrating sphere technique. The external PL efficiency of MEH-PPV was estimated to be 8 ($\pm$2)% together with the value of 0.02 1m/W for the external EL efficiency. This PL efficiency is in good agreement with published values, indicating that our PL efficiency measurements are somewhat legitimate. We believe this study might contribute to the research and development of organic materials for optoelectronic devices.

• Publications of The Korean Astronomical Society
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• v.16 no.1
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• pp.31-36
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• 2001

We present the characteristics of the 2K CCD camera at the Bohyunsan Optical Astronomy Observatory of the Korea Astronomy Observatory at the time of its development. The purpose of this paper is to support the observers who may need detailed information on the characteristics of the camera and to provide helpful information on the optimization' of a CCD camera for those who try to develop their own camera. The 2K CCD camera was optimized to have a gain of $1.8e^-/ADU$ and a read out noise of $7e^-$ from an experiment using radioactive $^{55}Fe$ X-ray source. The charge transfer efficiency was measured as 0.9999976 for serial and 0.9999942 for parallel direction, which means $0.5\%$ charge loss along the serial direction and $1.2\%$ along the parallel direction across the chip. The quantum efficiency of the camera was measured from an experiment using a homogeneous light source consisting of a halogen lamp and an integrating sphere with a monochromator. The resulting quantum efficiency of the camera peaked at the wavelength range 600-700 nm with the value of $\~0.89$.

• Journal of Technologic Dentistry
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• v.33 no.4
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• pp.313-321
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• 2011

Purpose: The purpose of this study was to compare color parameters of different fabrication method of Lava ceram powder, Lava DVS blocks, IPS e.max ceram and IPS e.max zirpress. Methods: The three available shades(A1, A2, A3.5) of Lava & Kavo zirconia blocks were examined. For each of three colors, three different thickness were tested, 5 times of measurement frequency. The measurements were made using a spectrophotometer equipped with an integrating sphere using the CIE $L^*$, $a^*$, $b^*$ colorimetric system. Results: Lava build-up group and Lava DVS group showed clinically perceived color difference, on the other hand IPS e.max build-up group and IPS e.max zirpress group did not show clinically perceived color difference to shade allowed on core. When the thickness of porcelain veneer increased from Lava and IPS e.max groups, color differences(${\Delta}E$) were decreased. Conclusion: All-ceramic system has color characteristics that clinicians have to consider when selecting materials. Also, manufacturers of different porcelain systems must make every effort to achieve color reproducibility.

• Journal of the Korean Society of Clothing and Textiles
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• v.28 no.3_4
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• pp.472-482
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• 2004

As the sphere of consumers' shopping behavior expands, the need to understand shopping orientation also increases. Yet, there has been few research that investigated the nature of clothing shopping orientation[CSO]. Thus, more research that accounts for CSO is needed. The purpose of this study is to determine the concept of CSO. In order to study CSO, documentary research was conducted. The results of this study were as follows: In order to identify the concept of CSO, the concept of general shopping orientation was determined first. The results indicated that the general shopping orientation was a shopping specific lifestyle. Based on this, the concept of CSO was determined. Through investigating the relationship between clothing lifestyle and CSO, and comparing the general shopping orientation and CSO, the concept of CSO was ultimately determined as a clothing shopping specific life style, that is, a patternized clothing shopping aspect integrating consumer's activity, interest, and opinion relating to clothing shopping. It comprehends both behavioral and psychological aspects appearing while the clothing shopping, and before and after the clothing shopping. The results of this study would be useful to reduce the confusion between the concept of CSO and other similar concepts, and to guide valid research on CSO.

• The Bulletin of The Korean Astronomical Society
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• v.36 no.2
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• pp.155.2-155.2
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• 2011

We present development of the calibration system for IGRINS (the Immersion GRating Infrared Spectrograph). We mainly use Th-Ar and U hollow cathode lamp as the spectral calibration source and telluric features can be used additionally. For the flat source, we selected a 3000K tungsten halogen lamp with 2 inch integrating sphere. From Light Tools simulation, the result flat image through calibration optics satisfied <1% flatness error requirement. We also present mechanical design of calibration box that will be attached on the IGRINS dewar. Three moving stages are designed to perform switching mechanism between all of the observing modes - target observation, flat, precision RV measurement, and spectro-polarimetric observation.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.67 no.1
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• pp.33-36
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• 2018

The purpose of this study is to improve the efficiency of anti-pollution film for PV module. The anti-pollution coating process was performed on a glass substrate, which is the same material as the glass substrate for the PV module. We coated the anti-pollution film on the glass substrate by spray coating. After coating process, annealing process was performed during 1 hour at $200^{\circ}C$, $300^{\circ}C$, and $400^{\circ}C$. And then we analyzed the surface characteristics according to the annealing temperature of the film. Annealing process can also improve the durability of the coated film. And then we analyzed the anti-pollution characteristics, particle size of anti-pollution film, light transmittance. The particle size of anti-pollution film was analyzed with FE-SEM. The light transmittance was analyzed with UV-Visible spectroscopy including integrating sphere.

• Journal of IKEEE
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• v.24 no.1
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• pp.140-146
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• 2020

We investigated light extraction film based on polymer dispersed liquid crystal (PDLC) for application in organic light emitting diodes (OLEDs). At least 30 seconds of direct UV irradiation process for curing PDLC film on a bottom-emitting OLEDs was successfully achieved without damage on the intrinsic properties of the OLED. We demonstrated that high haze and transmittance can be tuned simultaneously by controlling the UV curing time. By adding PDLC as an external layer without any additional treatment, the light scattering and extraction is increased. Consequently, a PDLC scattering film with 89.8% and 59.9 of total transmittance and haze respectively, achieved about 16% of light intensity enhancement from integrating sphere measurement.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.2
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• pp.210.1-210.1
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• 2012

We report technique used for improved measurement uncertainties for Photon detection efficiency(PDE) of $1mm^2$ single pixel SiPM. It consists of 470nm LED light source, two 2-inch integrating sphere and two NIST calibrated silicon photodiodes that have ${\pm}2.4%$ calibration error. With raytracing simulation of our experimental setup, we predict number of photon into SiPM and measurement uncertainty. For MPPC, Hamamatsu suggested PDE(1600 micro pixel) including crosstalk and afterpulse is 23.5% at 470 nm. By using new low calibration error photodiode and raytracing simulation, our simulation result has ${\pm}3%$ measurement uncertainty. The technical detail of measurement, simulation are presented with the results and implication.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.454-454
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• 2010

In order to achieve a high efficient a-Si solar cell, the TCO (transparent conductive oxide) substrates are required to be a low sheet resistivity, a high transparency, and a textured surface with light trapping effect. Recently, a zinc oxide (ZnO) thin film attracts our attention as new coating material having a good transparent and conductive for TCO of solar cells. In this paper the optical properties of $H_2$ post-treated BZO (boron doped ZnO, ZnO:B) thin film are investigated with $O_2$-plasma treatment. The BZO thin films by MOCVD (Metal Organic Chemical Vapor Deposition) are investigated and the samples of $H_2$ post-treated BZO thin film are tested with $O_2$-plasma treatment by plasma treatment system with 13.56 MHz as RIE (Reactive Ion Etching) type. We measured the optical properties and surface morphology of BZO thin film with and without $O_2$-plasma treatment. The optical properties such as transmittance, reflectance and haze are measured with integrating sphere and ellipsometer. This result of the BZO thin film with and without $O_2$-plasma treatment is application to the TCO for solar cells.

• Korean Journal of Remote Sensing
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• v.24 no.5
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• pp.397-408
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• 2008

A wide variety of applications of imaging spectrometer have been proved using data from airborne systems. The Compact Airborne Imaging Spectrometer System (CAISS) was jointly designed and developed as the airborne hyperspectral imaging system by Korea Aerospace Research Institute (KARI) and ELOP inc., Israel. The primary mission of the CAISS is to acquire and provide full contiguous spectral information with high spatial resolution for advanced applications in the field of remote sensing. The CAISS consists of six physical units; the camera system, the gyro-stabilized mount, the jig, the GPS/INS, the power inverter and distributor, and the operating system. These subsystems are to be tested and verified in the laboratory before the flight. Especially the camera system of the CAISS has to be calibrated and validated with the calibration equipments such as the integrating sphere and spectral lamps. To improve data quality and its availability, it is the most important to understand the mechanism of imaging spectrometer system and the radiometric and spectral characteristics. The several performance tests of the CAISS were conducted in the camera system level. This paper presents the major characteristics of the CAISS, and summarizes the results of performance tests in the camera system level.