• 한국재료학회지
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• 제9권2호
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• pp.173-180
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• 1999

Thermally evaporated ZnTe films were investigated as a back contact material for CdS/CdTe solar cells. Two deposition methods, coevaporation and double-layer methods, were used for Cu doping in ZnTe films. ZnTe layers (0.2$\mu\textrm{m}$ thick) were deposited either on glass or on CdS/CdTe substrates without intentional heating of the substrates. Post-deposition annealing was performed at 200,300 and $400^{\circ}C$ for 3,6 and 9 minutes, respectively. Band gap of 2.2eV was measured for both undoped and doped films and a slight change in the shape of absorption spectra was observed in Cu-doped samples after annealing at $400^{\circ}C$. The resistivity of as-deposited ZnTe decreased from 10\ulcorner~10\ulcornerΩcm down to 10\ulcornerΩcm as Cu concentration increased from 0 to 14 at.%. There was not a noticeable change in less of annealing temperature up to $300^{\circ}C$ whereas films annealed at $400^{\circ}C$ revealed hexagonal (101) orientations as well. Some of Cu-doped ZnTe revealed x-ray diffraction (XRD) peaks related with Cu\ulcornerTe(x=1.75~2). Grain growth was observed from about 20nm in as-deposited films to 50nm after annealing at $400^{\circ}C$ by scanning electron microscopy (SEM). Cu distribution in ZnTe films was not uniform according to Auger electron spectroscopy (AES) measurements.

• 한국전기전자재료학회논문지
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• 제16권10호
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• pp.897-901
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• 2003

The microstructure and varistor characteristics of ZnO-Pr$_{6}$O$_{11}$-CoO-Cr$_2$O$_3$-Dy$_2$O$_3$(ZPCCD)-based ceramics were investigated with Dy$_2$O$_3$ content in the range of 0.0∼2.0 mol%. As Dy$_2$O$_3$ content is increased, the average grain size was decreased in the range of 18.6∼4.7 $\mu$m and the density was decreased in the range of 5.53∼4.34 g/cm$^3$. While, the varistor voltage was increased in the range of 39.4∼436.6 V/mm and the nonlinear exponent was in the range of 4.5-66.6 with increasing Dy$_2$O$_3$ content. The addition of Dy$_2$O$_3$ highly enhanced the nonlinear properties of varistors, compared with the ceramics without Dy$_2$O$_3$ Particularly, the ceramics with Dy$_2$O$_3$ content of 0.5 mol% exhibited the highest nonlinearity, in which the nonlinear exponent is 66.6 and the leakage current is 1.2 $\mu$A.A.A.

• 한국식품과학회지
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• 제3권3호
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• pp.135-143
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• 1971

유기수은제 농약은 도열병 방제의 목적으로 다량 살포되는데 그 결과로 식품중의 수은잔류량증가로 그 피해가 예견되어 수은함량을 검색할 필요성이 요구된다. 그러나 종래 분석방법인 dithizone 비색법은 시료 분해시 수은 화합물의 손실, 유출물의 변동으로 인하여 정확도를 기대하기 어려운점이 있으나 본 연구에서 시도한 방사화 분석법에 의하면 극미량도 고감도로 정량 할 수가 있다. 본 실험에서는 곡류, 야채, 육류, 과일, 계란을 산지별로 시료를 수집하여 건조, 포장하여 vial에 넣고 열중성자속 $3.8{\times}10^{12}\;n/cm\;sec$에 15시간 조사하였다. 이 시료를 Bethge 장치로 분해시켜 수은을 증류하여 TMC 100 Channel pluse height analyzer로 $^{203}Hg$ 방사능율 0.279 MeV Photopeck로 측정하였다. 시료별로 수은 함량은 곡류 $0.033{\sim}0.250\;ppm$, 야채 $0.012{\sim}0.190\;ppm$, 닭고기 $0.04{\sim}0.07\;ppm$, 과일 $0.085{\sim}0.145\;ppm$, 계란$0.051{\sim}0.165\;ppm$, 콩나물 0.123 ppm 됨을 알게 되었다.

• 한국재료학회지
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• 제23권11호
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• pp.638-642
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• 2013

Chalcopyrite $CuInSe_2$(CIS) is considered to be an effective light-absorbing material for thin film photovoltaic solar cells. CIS thin films have been electrodeposited onto Mo coated and ITO glass substrates in potentiostatic mode at room temperature. The deposition mechanism of CIS thin films has been studied using the cyclic voltammetry (CV) technique. A cyclic voltammetric study was performed in unitary Cu, In, and Se systems, binary Cu-Se and In-Se systems, and a ternary Cu-In-Se system. The reduction peaks of the ITO substrate were examined in separate $Cu^{2+}$, $In^{3+}$, and $Se^{4+}$ solutions. Electrodeposition experiments were conducted with varying deposition potentials and electrolyte bath conditions. The morphological and compositional properties of the CIS thin films were examined by field emission scanning electron microscopy (FE-SEM) and energy dispersive spectroscopy (EDS). The surface morphology of as-deposited CIS films exhibits spherical and large-sized clusters. The deposition potential has a significant effect on the film morphology and/or grain size, such that the structure tended to grow according to the increase of the deposition potential. A CIS layer deposited at -0.6 V nearly approached the stoichiometric ratio of $CuIn_{0.8}Se_{1.8}$. The growth potential plays an important role in controlling the stoichiometry of CIS films.

• 한국추진공학회지
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• 제19권2호
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• pp.1-8
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• 2015

이중펄스 로켓 추진기관은 하나의 펄스분리장치에 의해 분리된 2개의 추진제 그레인을 가진 변형된 고체 추진기관이다. 이러한 추진기관의 주요 성능은 펄스분리장치 홀 면적대 노즐 목 면적비의 변화에 영향을 받는다. 본 연구에서는 펄스분리장치 홀 면적대 노즐 목 면적비 변화에 따른 내부유동특성을 고찰하기 위해 유동해석을 수행하였다. 유동해석에 사용된 기체로는 hot gas로 HTPB/AP계 복합추진제 연소가스와 cold gas로 질소가스롤 사용하였다. 이중펄스 로켓 추진기관의 내부유동해석 결과는 공압실험 결과와 비교 분석을 통해 검증하였다. 본 논문에서는 상용 CFD(Computational Fluid Dynamics) 코드인 ANSYS FLUENT V14.5를 이용하여 유동을 모사하였다.

• 한국표면공학회지
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• 제55권2호
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• pp.91-95
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• 2022

ZnO single layer (60 nm thick) and ZnO with Ag interlayer (ZnO/Ag/ZnO; ZAZ) films were deposited on the glass substrates by using radio frequency (RF) and direct current (DC) magnetron sputter to evaluate the effectiveness of Ag interlayer on the optical visible transmittance and the conductivity of the films. In the ZAZ films, the thickness of ZnO layers was kept at 30 nm, while the Ag thickness was varied as 5, 10, 15 and 20 nm. In X-ray diffraction (XRD) analysis, ZnO films show the (002) diffraction peak and ZAZ films also show the weak ZnO (002) peak and Ag (111) diffraction peak. As a thickness of Ag interlayer increased to 20 nm, the grain size of the Ag films enlarged to 11.42 nm and the optical band gap also increased from 4.15 to 4.22 eV with carrier concentration increasing from 4.9 to 10.5×10²¹ cm^-3. In figure of merit measurements, the ZAZ films with a 10 nm thick Ag interlayer showed the higher figure of merit of 4.0×10^-3 Ω^-1 than the ZnO single layer and another ZAZ films. From the experimental result, it is assumed that the Ag interlayer enhanced effectively the opto-electrical performance of the ZAZ films.

• Nuclear Engineering and Technology
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• 제55권8호
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• pp.2797-2801
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• 2023

CdZnTeSe (CZTS) has attracted attention for applications in X- and gamma-ray detectors owing to its improved properties compared to those of CdZnTe (CZT). In this study, we grew and processed single crystals of CZT and CZTS using the Bridgeman method to confirm the feasibility of using a dosimeter for high-energy X-rays in radiotherapy. We evaluated their linearity and precision using the coefficient of determination (R²) and relative standard deviation (RSD). CZTS showed sufficient RSD values lower than 1.5% of the standard for X-ray dosimetry, whereas CZT's RSD values increased dramatically under some conditions. CZTS exhibited an R² value of 0.9968 at 500 V/cm, whereas CZT has an R² value of 0.9373 under the same conditions. The X-ray response of CZTS maintains its pulse shape at various dose rates, and its properties are improved by adding selenium to the CdTe matrix to lower the defect density and sub-grain boundaries. Thus, we validated that CZTS shows a better response than CZT to high-energy X-rays used for radiotherapy. Further, the applicability of an onboard imager, a high-energy X-ray (>6 MV) image, is presented. The proposed methodology and results can guide future advances in X-ray dose detection.

• 한국작물학회:학술대회논문집
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• 한국작물학회 2022년도 추계학술대회
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• pp.261-261
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• 2022

Cowpea [Vigna unguiculata (L.) Walp] is one of the most important grain legumes that enhance soil fertility and is well-adapted to various abiotic stress. Also, it is cultivated worldwide as a tropical annual crop, and the semi-arid regions are known as the main cowpea-produced regions. However, accumulation of soil salinity induced by low rainfall in these regions is reducing crop yields and quality. In general, plants exposed to soil salinity cause an accumulation of high ion chloride, which leads to the degradation of root and leaf proteins. In this study, we identified candidate genes associated with salinity tolerance through an analysis of differentially expressed genes (DEGs) in four cowpea germplasms with contrasting salinity tolerance. A total of 553,776,035 short reads were obtained using the Illumina Novaseq 6000 platform for RNA-Seq, which were subsequently aligned to the reference genome of cowpea Vunguiculata v1.2. A total of9,806 DEGs were identified between NaCl treatment and control of four cowpea germplasms. Among these DEGs, functions related to salt stress such as calcium transporter and cytochrome-450 family were associated with salt stress. In GO analysis and KEGG analysis, these DEGs were enriched in terms such as the "phosphorylation", ''extracellular region", and "ion binding". These RNA-seq results will improve the understanding of the salt tolerance of cowpea and can be used as useful basic data for molecular breeding technology in the future.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1993년도 추계학술대회 논문집
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• pp.17-20
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• 1993

In this paper, the (1-x)($Sr_{0.50}$$Pb_{0.25}$$Ba_{0.25}$)$TiO_3$-x $Bi_2$$Ti_3$$O_{9}$(x=0,4,6,8[mol.%]) ceramics with paraelectric properties were, fabricated by mixed oxide method. The dielectric and structural properties of ceramics were studied with sintering temperature and addition of $Bi_2Ti_3O_{9}$, and the application for the high - voltage capacitor was investigated. In the specimens with sintering at 1350[$^{\circ}C$], sintered density was showed the highest value of 5.745[g/cm$^3$]. Increasing of sintering temperature, average grain size was increased. The specimen. ($Sr_{0.50}$$Pb_{0.25}$$Ba_{0.25}$)$TiO_3$sintered at 1350[$^{\circ}C$] showed good dielectric properties and breakdown voltage was showed the highest value of 200[kV]. Temperature coefficient of capacitance was stabilized in specimens added $Bi_2Ti_3O_{9}$ Sintered density. dielectric properties and breakdown voltage ware decreased with increasing the contents of $Bi_2Ti_3O_{9}$.

• 태양에너지
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• 제20권2호
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• pp.43-54
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• 2000

동시 진공증발법을 이용하여 coming glass, soda-lime glass, Mo가 증착된 soda-lime glass 위에 $Cu(In_{1-x}Ga_x)Se_2$ 박막을 증착하였다. Soda-lime glass 위에서 제조된 $Cu(In_{0.5}Ga_{0.5})Se_2$ 박막의 전기비저항값과 정공농도는Cu/(In+Ga)비에 큰 영향을 받지 않았다. Soda-lime glass위에서의 $Cu(In_{1-x}Ga_x)Se_2$ 박막내부와 표면에는 Na이 검출되었고, 표면의 Na는 산소와 결합하고 있었으며, Cu가 부족한 조성에서 이차상이 형성되었다. Ga/(In+Ga)비가 증가할수록 $Cu(In_{1-x}Ga_x)Se_2$ 박막은 회절 peak들의 큰 회절각으로 이동, 초격자 peak등의 분리, 결정립 크기의 감소가 관찰되었다. $Cu_{0.91}(In_{1-x}Ga_x)Se_2$ 박막은 Ga/(In+Ga)비에 무관하게 전기적으로 p-type을 나타내었다. Ag/n-ZnO /i-Zno/CdS/$Cu_{0.91}(In_{0.7}Ga_{0.3})Se_2$/Mo/glass구조의 태양전지를 제조하였으며, 태양전지변환효율(Eff.) = 14.48%, 단락전류밀도(Jsc) = $34.88mA/cm^2$, 개방전압(Voc) =581.5 mV, 충실도(F.F) = 0.714을 나타내었다.