• Nuclear Engineering and Technology
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• v.55 no.8
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• pp.2873-2878
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• 2023

The purpose of this study is to perform radiation monitoring by acquiring gamma images and real-time optical images for ^99mTc vial source using charge couple device (CCD) cameras equipped with the proposed compact gamma camera. The compact gamma camera measures 86×65×78.5 mm³ and weighs 934 g. It is equipped with a metal 3D printed diverging collimator manufactured in a 45 field of view (FOV) to detect the location of the source. The circuit's system uses system-on-chip (SoC) and field-programmable-gate-array (FPGA) to establish a good connection between hardware and software. In detection modules, the photodetector (multi-pixel photon counters) is tiled at 8×8 to expand the activation area and improve sensitivity. The gadolinium aluminium gallium garnet (GAGG) measuring 0.5×0.5×3.5 mm³ was arranged in 38×38 arrays. Intrinsic and extrinsic performance tests such as energy spectrum, uniformity, and system sensitivity for other radioisotopes, and sensitivity evaluation at edges within FOV were conducted. The compact gamma camera can be mounted on unmanned equipment such as drones and robots that require miniaturization and light weight, so a wide range of applications in various fields are possible.

• The Korean Journal of Nuclear Medicine
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• v.30 no.1
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• pp.139-144
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• 1996

갈륨스캔은 여러 종류의 염증성 질환 및 종양을 발견하기 위해 사용되고 있다. 특히 림프종은 갈륨스캔에서 양성율이 비교적 높은 종양으로 알려져 있다. 하지만 기존의 평면 영상만으로는 작은 크기의 종괴나 다른 장기에 의해 가려져 있는 경우에 위음성 결과를 보일 수 있었다. 최근 단일광자 방출 전산화 단층촬영(SPCET)을 도입하여 평면영상에 비해 더 나은 공간해상력으로 많은 정보를 얻고 있다. 저자들은 비호지킨 림프종 환자 30명을 대상으로 갈륨스캔 평면영상과 SPECT 영상을 얻어 비교하였다. 병변의 부위별로 두경부, 흉부, 복부에서 평면영상의 예민도는 각각 71%, 73%, 81%였으며, SPECT 영상의 예민도는 91%, 93%, 96%였다. CT 등 방사선학적 검사소견과 임상소견을 기준으로 하였을 때 위음성율은 평면영상의 경우 24%, SPECT 6.5%였다. 장의 방사능으로 인한 섭취와 폐문부 및 침샘의 비대칭적 섭취로 인한 위양성례가 4예 있었다. 결론적으로 비호지킨 림프종의 진단 및 병기를 결정하는데 있어서 갈륨스캔이 유용하며, SPCET 영상을 얻음으로써 더 나은 해부학적 위치 및 정확한 범위를 보여 줄 수 있을 것으로 생각된다.

• Nuclear Engineering and Technology
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• v.56 no.6
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• pp.2412-2420
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• 2024

The International Atomic Energy Agency (IAEA) mandates safeguards to ensure non-proliferation of nuclear materials. Among inspection techniques used to detect partial defects within spent nuclear fuel (SNF), gamma emission tomography (GET) has been reported to be reliable for detection of partial defects on a pin-by-pin level. Conventional GET, however, is limited by low detection efficiency due to the high density of nuclear fuel rods and self-absorption. This paper proposes a new type of GET named Spent Fuel Internal Tomography (SFIT), which can acquire sinograms at the guide tube. The proposed device consists of the housing, shielding, C-shaped collimator, reflector, and gadolinium aluminum gallium garnet (GAGG) scintillator. For accurate attenuation correction, the source-distinguishable range of the SFIT device was determined using MC simulation to the region away from the proposed device to the second layer. For enhanced inspection accuracy, a proposed specific source-discrimination algorithm was applied. With this, the SFIT device successfully distinguished all source locations. The comparison of images of the existing and proposed inspection methods showed that the proposed method, having successfully distinguished all sources, afforded a 150 % inspection accuracy improvement.

• Applied Chemistry for Engineering
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• v.18 no.3
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• pp.218-226
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• 2007

The stereoselective synthesis of chiral terminal epoxides is of immense academic and industrial interest due to their utility as versatile starting materials as well as chiral intermediates. In this study, new dinuclear chiral Co (salen) complexes bearing gallium-, indium- and tallium-chloride have been synthesized and characterized. The mass and EXAFS spectra provided the direct evidence of formation of dinuclear complex. Their catalytic activity and selectivity have been demonstrated for the asymmetric ring opening of various terminal epoxides having ether or ester groups by hydrolytic kinetic resolution technology. The easily prepared dimeric complexes exhibited very high enantioselectivity for the asymmetric ring opening of epoxides with $H_2O$ nucleophile, providing enantiomerically enriched terminal epoxides (> 99% ee). The dimeric structured chiral salen showed remarkably enhanced reactivity and may be employed substantially lower loadings than its monomeric analogues. The system described in this work is very efficient for the synthesis of chiral epoxide and 1,2-diol intermediates

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.18 no.3
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• pp.101-104
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• 2008

GaN films were grown on the vertical and horizontal reactors by the hydride vapour phase epitaxy (HVPE). The structural and optical characteristics of the GaN films were investigated depending on the reactor-type. GaN epilayers were characterized by double crystal X-ray diffraction (DC-XRD), transmission electron microscopy (TEM) and photoluminescence (PL). Surface defects of two kinds of the GaN films were revealed by the wet chemical etching method, using $H_3PO_4$ acid at $200^{\circ}C$ for 8 minutes. Hexagonal etch pits were analyzed by optical microscopy and SEM. Etch pit densities were calculated to be approximately $1.4{\times}10^7$ and $1.2{\times}10^6\;cm^{-2}$ for GaN layers grown on horizontal and vertical reactors, respectively. Those results show GaN grown in the vertical reactor having a better quality of optical properties and crystallinity than that in the horizontal reactor.

• Mineral and Industry
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• v.27
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• pp.8-15
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• 2014

In this study, a proposal for revision of HSK Code was established on legally designated minerals and national stockpile minerals. It is difficult to exactly identify trade balances of minerals, such as lithium ore, rare earth ore, serpentine, kidney stone in legally designated minerals and ingot of indium, ferro-tungsten, ingot of antimony, granule of selenium, gallium, lanthanum oxide, cerium carbonate in national stockpile minerals because HSK Codes of them were not allocated separately. Furthermore, specific use, standard, component, type of products cannot be exactly identified in current HSK Code system. Therefore, it is makes rule to separately manage minerals which were managed by government such as legally designated minerals and national stockpile minerals. However, a proposal for revision of HSK Code system was established to comply with international standard(HS Code) and the items over a certain size(amounts : over 50 mil.$, volumes : over 5000 ton) were selected as revised subjects. Moreover hierarchies between HSK Codes were considered.

• Journal of the Korean Ceramic Society
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• v.53 no.1
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• pp.110-115
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• 2016

We prepared a working electrode (WE) coated with 0 ~ 50 nm-thick indium gallium zinc oxide(IGZO) by using RF sputtering to improve the energy conversion efficiency (ECE) of a dye sensitized solar cell (DSSC). Transmission electron microscope (TEM) and energy dispersive spectroscopy (EDS) were used to analyze the microstructure and composition of the IGZO layer. UV-VIS-NIR spectroscopy was used to determine the transparency of the WE with IGZO layers. A solar simulator and a potentiostat were used to confirm the photovoltaic properties of the DSSC with IGZO layer. From the results of the microstructural analysis, we were able to confirm the successful deposition of an amorphous IGZO layer with the expected thickness and composition. From the UV-VIS-NIR analysis, we were able to verify that the transparency decreased when the thickness of IGZO increased, while the transparency was over 90% for all thicknesses. The photovoltaic results show that the ECE became 4.30% with the IGZO layer compared to 3.93% without the IGZO layer. As the results show that electron mobility increased when an IGZO layer was coated on the $TiO_2$ layer, it is confirmed that the ECE of a DSSC can be enhanced by employing an appropriate thickness of IGZO on the $TiO_2$ layer.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.28 no.6
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• pp.351-359
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• 2015

Next-generation displays should be transparent and flexible as well as having high resolution and frame number. The main factor for active matrix organic light emitting diode and next-generation displays is the development of TFTs (thin-film transistors) with high mobility and large area uniformity. The TFTs used for transparent displays are mainly oxide TFT that has oxide semiconductor as channel layer. Zinc-oxide based substances such as indium-gallium-zinc-oxide has attracted attention in the display industry. In this paper, the mobility improvement of low cost oxide TFT is studied for fast operating next-generation displays by overcoming disadvantages of amorphous silicon TFT that has low mobility and poly silicon TFT that requires expensive equipment for complex process and doping process.

• Journal of the Korean Electrochemical Society
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• v.14 no.4
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• pp.225-230
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• 2011

CIGS solar cells are kind of thin film solar cells, which are studied several years. CdS buffer layer that makes heterojunction between window layer and absorbing layer was one of issue in the CIGS solar cell study. New types of buffer layer consisted of indium sulfide are being studied these days owing to high price and environmental harmful of CdS. In this study, we demonstrated electrochemical synthesis of indium sulfide film as a buffer layer, which is cheaper and faster than other methods. A uniform indium sulfide film was obtained by applying two different alternating potentials. The band gap of the film was optimized by controlling temperature during the electrochemical synthesis. Using x-ray photoelectron spectroscopy and diffraction method we confirmed that ${\beta}$-indium sulfide was formed on ITO electrode surface.

• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.85.1-85.1
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• 2010

$Cu(In,Ga)Se_2$ (CIGS) thin film solar cell is currently 19.5% higher efficiency and developing a large area technology. The structure of CIGS solar cell that make five unit layers as back contact, light absorption, buffer, front transparent conducting electrode and antireflection to make them sequentially forming. Materials and various compositions of thin film unit which also manufacture a variety method used by the physical and chemical method for CIGS solar cell. The construction and performance test of evaporator for CIGS thin film solar cell has been done. The vapor pressures were changed by using vapor flux meter. The vapor pressure were copper (Cu) $2.1{\times}10^{-7}{\sim}3.0{\times}10^{-7}$ Torr, indium (In) $8.0{\times}10^{-7}{\sim}9.0{\times}10^{-7}$ Torr, gallium (Ga) $1.4{\times}10^{-7}{\sim}2.8{\times}10^{-7}$ Torr, and selenium (Se) $2.1{\times}10^{-6}{\sim}3.2{\times}10^{-6}$ Torr, respectively. The characteristics of the CIGS thin film was investigated by using X-ray diffraction (XRD), scanning electron microscopy/energy dispersive spectroscopy (SEM/EDS) and photoluminescence (PL) spectroscopy using a He-Ne laser. In PL spectrum, temperature dependencies of PL spectra were measured at 1137 nm wavelength.