• 한국전기전자재료학회논문지
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• 제16권12호
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• pp.1121-1124
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• 2003

We report the photo (PL) and electro luminescence (EL) properties of new conjugated compounds based on imidazole moiety, 4,4' -di(4,5 diphenyl-N-imidazolyl)stilbene(DDPIS) and 4,4'-di(2,4,5-triphenyl-N-imidazolyl)stilbene(DTPIS), as emitting materials. ITO/m-MTDATA/NPB/DDPIS/Alq3/LiF/AI device shows blue EL spectrum at 456 ㎚ and 0.3 cd/ A and turn on voltage at 7 ∼ 8 V. DTPIS shows blue EL spectrum at around λmax=453㎚ and 0.5 cd/A efficiency in ITO/m-MTDATA/NPB/DTPIS/Alq3/LiF/Al device.

• 한국전기전자재료학회논문지
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• 제19권4호
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• pp.322-327
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• 2006

CdS films have been prepared on polycarbonate, polyethylene terephthalate, and Coming 7059 substrates by r.f magnetron sputtering technique at room temperature. A comparison of the properties of the films deposited on polymer and glass substrates was performed. In addition, the influence of the sputter power on the structural and optical properties of these films was evaluated. The XRD measurements revealed that CdS films were polycrystalline and retained the mixed structure of hexagonal wurtzite and cubic phase, regardless of substrate types. As the sputter power was increased from 75 to 150 Watt, the structure of CdS films was converted from the mixed of hexagonal and cubic phase to hexagonal phase. The morphology of CdS films is found to be continuous and dense. Also, the grain of CdS films is larger with increasing the sputter power. The average transmittance exceeded 80 % in the visible spectrum for all films and decreases slightly with the sputter power.

• Bulletin of the Korean Chemical Society
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• 제32권7호
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• pp.2207-2211
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• 2011

Colloidal cadmium telluride (CdTe) quantum dots (QDs) and their nanoparticles have been synthesized by one pot sonochemical reactions under multibubble sonoluminescence (MBSL) conditions, which are quite mild and facile compared to other typical high temperature solution-based methods. For a typical reaction, $CdCl_2$ and tellurium powder with hexadecylamine and trioctylphosphine/trioctylphosphineoxide (TOP/TOPO) as a dispersant were sonicated in toluene solvent at 20 KHz and a power of 220W for 5-40 min at 60 $^{\circ}C$. The sizes of CdTe particles, in a very wide size range from 2 nm-30 ${\mu}m$, were controllable by varying the sonicating and thermal heating conditions. The prepared CdTe QDs show different colors from pale yellow to dark brown and corresponding photoluminescence properties due mainly to the quantum confinement effect. The CdTe nanoparticles of about 20 nm in average were found to have band gap of 1.53 eV, which is the most optimally matched band gap to solar spectrum.

• 반도체디스플레이기술학회지
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• 제4권1호
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• pp.29-34
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• 2005

Tungsten oxide($WO_{3}$) is suitable to materials for photochromic window in the visible region. The resistivities of CdS, $WO_{3}$, and $WO_{3}$/CdS films prepared by thermal evaporation method were $4.61\times 10\^{3}$, $7.59\times10^{3}$, and $6.29\times10^{3}$ $\omega$ cm. And x-ray diffraction patterns of CdS, $WO_{3}$/CdS films showed a preferred orientation of hexagonal(002), and the monoclinic(020) structure, respectively. The optical transmission were measured that the cut-on wavelength were 510nm, 380nm for CdS and $WO_{3}$ films respectively, and the transmission spectrum of $WO_{3}$/CdS was shifted into the visible region. Photoluminescence(PL) spectra showed the two peaks at 2.8 eV and 3.2 eV for the as-grown sample($WO_{3}$/CdS ($500{\AA}$), but the other sample($WO_{3}$/CdS ($1000{\AA}$)) had a peak energy value of 2.8 eV. The photochromism of $WO_{3}$/CdS films showed that the excitation of electron-hole pairs and subsequent coloration is shifted into visible-light range. And the spectral behavior of coloration turned out to be proportional to the excited electron-hole pairs creation rate of CdS film. This result is interpreted in terms of charge carrier injection from the CdS-layer into the $WO_{3}$ films. We found a value of about 2.8 eV of $WO_{3}$/CdS film which is somewhat higher than peak energy of 2.54 eV using CBD prepared by Bechinger et. al.

• 한국진공학회지
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• 제1권1호
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• pp.126-133
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• 1992

E-Beam 기법을 이용하여 증착시킨 Ag doped CdS 박막은 육방정계이고 공기, Ar 분위기에서 $^550{\circ}C$로 열처리한 결과 grain size가 1$mu extrm{m}$ 정도로 성장되었고, Van Der Pauw 방법으로 구한 Hall data로부터 CdS crystal은 n형 반도체이고 상온에서의 carrier 농 도는 2.7 $\times$ 1011cm-3이고 Hall mobility는 5.8 $\times$ 102cm2V-1sec-1정도임을 알 수 있었다. CdS : Ag 박막의 PL spectra는 Gaussian curve를 보여주었고, spectra peak는 파장이 520nm 근처에 위치하고 있으며, CdS : Ag 박막에서의 광전류(pc)와 암전류(dc)의 ratio(pc/dc)는 공기 중에서 열처리한 시료의 값이 크다는 것을 알 수 있었다.

• 한국생물물리학회:학술대회논문집
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• 한국생물물리학회 2003년도 정기총회 및 학술발표회
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• pp.69-69
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• 2003

Human CD99 is a ubiquitous 32-kDa transmembrane protein encoded by the mic2 gene. The major cellular functions of CD99 protein are related to homotypic cell adhension, apoptosis, vesicular protein transport, and differentiation of thymocytes or T cells. Recently it has been reported that expression of a splice variant of CD99 transmembrane protein (Type I and Type II) increases invasive ability of human breast cancer cells. To understand structural basis for cellular functions of CD99 (Type I), we have initiated studies on hCD99$^{TMcytoI}$ and hCD99$^{cytoI}$ using circular dichroism (CD) and multi-dimensional NMR spectroscopy. CD spectrum of hCD99$^{TMcytoI}$ in the presence of 200mM DPC and CHAPS displayed an existence $\alpha$-helical conformation. The solution structure of hCD99$^{cytoI}$ determined by NMR is composed of one N-terminal $\alpha$-helix, $\alpha$A, two C-terminal short $\alpha$-helix segments, $\alpha$B and $\alpha$C. While $\alpha$A and $\alpha$B are connected by the long flexible loop, $\alpha$B and $\alpha$C connected by type III$\beta$-turn. Although it has been rarely figured out the correlation between structure and functional mechanism of hCD99$^{TMcytoI}$ and hCD99$^{cytoI}$, there is possibility of dimerization or oligomerization. In addition, the feasible mechanism of hCD99$^{cytoI}$ is that it could have intramolecular interaction between the N- and C- terminal domain through large flexible AB loop.

• Nuclear Engineering and Technology
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• 제43권6호
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• pp.567-572
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• 2011

A sensitivity analysis of the methods used to evaluate the transport properties of a CdZnTe detector was performed using two different radiations (${\alpha}$ particle and gamma-ray) emitted from an $^{241}Am$ source. The mobility-lifetime products of the electron-hole pair in a planar CZT detector ($5{\times}5{\times}2\;mm^3$) were determined by fitting the peak position as a function of biased voltage data to the Hecht equation. To verify the accuracy of these products derived from ${\alpha}$ particles and low-energy gamma-rays, an energy spectrum considering the transport property of the CZT detector was simulated through a combination of the deposited energy and the charge collection efficiency at a specific position. It was found that the shaping time of the amplifier module significantly affects the determination of the (${\mu}{\tau}$) products; the ${\alpha}$ particle method was stabilized with an increase in the shaping time and was less sensitive to this change compared to when the gamma-ray method was used. In the case of the simulated energy spectrum with transport properties evaluated by the ${\alpha}$ particle method, the peak position and tail were slightly different from the measured result, whereas the energy spectrum derived from the low-energy gamma-ray was in good agreement with the experimental results. From these results, it was confirmed that low-energy gamma-rays are more useful when seeking to obtain the transport properties of carriers than ${\alpha}$ particles because the methods that use gamma-rays are less influenced by the surface condition of the CZT detector. Furthermore, the analysis system employed in this study, which was configured by a combination of Monte Carlo simulation and the Hecht model, is expected to be highly applicable to the study of the characteristics of CZT detectors.

• 분석과학
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• 제35권2호
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• pp.69-81
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• 2022

The method of measuring and classifying the energy category of neutrons directly using raw data acquired through a CZT detector is not satisfactory, in terms of accuracy and efficiency, because of its poor energy resolution and low measurement efficiency. Moreover, this method of measuring and analyzing the characteristics of low-energy or low-activity gamma-ray sources might be not accurate and efficient in the case of neutrons because of various factors, such as the noise of the CZT detector itself and the influence of environmental radiation. We have therefore developed an efficient method of analyzing radiation characteristics using a neutron and gamma-ray analysis algorithm for the rapid and clear identification of the type, energy, and radioactivity of gamma-ray sources as well as the detection and classification of the energy category (fast or thermal neutrons) of neutron sources, employing raw data acquired through a CZT detector. The neutron analysis algorithm is based on the fact that in the energy-spectrum channel of 558.6 keV emitted in the nuclear reaction ¹¹³Cd + ¹n → ¹¹⁴Cd + in the CZT detector, there is a notable difference in detection information between a CZT detector without a PE modulator and a CZT detector with a PE modulator, but there is no significant difference between the two detectors in other energy-spectrum channels. In addition, the gamma-ray analysis algorithm uses the difference in the detection information of the CZT detector between the unique characteristic energy-spectrum channel of a gamma-ray source and other channels. This efficient method of analyzing radiation characteristics is expected to be useful for the rapid radiation detection and accurate information collection on radiation sources, which are required to minimize radiation damage and manage accidents in national disaster situations, such as large-scale radioactivity leak accidents at nuclear power plants or nuclear material handling facilities.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 추계학술대회 논문집
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• pp.66-66
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• 2009

The photoconductive $CdGa_2Se_4$ layer was grown through the hot wall epitaxy method. From the photocurrent (PC) measurements, the three peaks in the PC spectra were associated with the band-to-band transitions. The PC intensities were observed to decrease with decreasing temperature. The valence-band splitting on $CdGa_2Se_4$ was also observed by means of the PC spectroscopy. The crystal field splitting and the spin orbit splitting turned out to be 0.1604 and 0.4179 eV at 10 K, respectively.

• 한국자기공명학회논문지
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• 제14권1호
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• pp.18-27
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• 2010

The NMR spectrum and spin-lattice relaxation times, $T_1$, of the $^{1}H$ nuclei in $(NH_{4})_{2}Cd_{2}(SO_{4})_{3}$ single crystals were obtained. The two minima in $T_1$ in the paraelectric phase are attributed to the reorientational motions of the $NH_{4}^{+}$ groups. The $^{1}H\;T_1$ of the $(NH_{4})_{2}Cd_{2}(SO_{4})_{3}$ crystals can be described with Bloembergen- Purcell-Pound (BPP) theory. The experimental value of $T_1$ can be expressed in terms of an isotropic correlation time ${\tau}_H$ for molecular motions by using the BPP theory, and determine the role of protons in these processes.