• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.20 no.2
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• pp.97-102
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• 2020

This paper relates with the Hybrid-SE-MMA (Signed-Error MMA) that is possible to improving the equalization performance by using the adaptive modulus and adaptive step size in SE-MMA adaptive equalizer for the minimizing the intersymbol interference. The equalizer tap coefficient is updatted use the error signal in MMA algorithm for adaptive equalizer. But the sign of error signal is used for the simplification of arithmetic operation in SE-MMA algorithm in order to updating the coefficient. By this simplification, we get the fast convergence speed and the reduce the algorithm processing speed, but not in the equalization performance. In this paper, it is possible to improve the equalization performance by computer simulation applying the adaptive modulus to the SE-MMA which is proposional to the power of equalizer output signal. In order to compare the improved equalization performance compared to the present SE-MMA, the recovered signal constellation that is the output of the equalizer, residual isi, MD(maximum distortion), MSE and the SER perfomance that means the robustness to the external noise were used. As a result of computer simulation, the Hybrid-SE-MMA improve equalization performance in the residual isi and MD, MSE, SER than the SE-MMA.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.17 no.1
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• pp.77-82
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• 2017

This paper related with the VSS_SE-MMA (Varying Step Size_Signed Error-MMA) which possible to improving the equalization performance that employing the varying adaptive step size based on the nonlinearities of error signal of SE-MMA (Signed Error-MMA), compensates the intersymbol interference by distortion occurs at the communication channel, in the transmitting the spectral efficient nonconstant modulus signal such as 16-QAM. The SE-MMA appeared to the reducing the computational arithematic operation using the polarity of error signal in the updating the tap coefficient of present MMA adaptive equalizer, but have a problem of equalization performance degradation. The VSS_SE-MMA improves the problem of such SE-MMA, using the varying step size consider the error signal in the update the adaptive equalizer tap coefficient, and its improved performance were confirmed by simulation. For this, the output signal constellation of equalizer, the residual isi and maximum distortion, MSE and SER were applied. As a result of computer simulation, it was confirmed that the VSS_SE-MMA algorithm has nearly same in convergence speed and has more good performance in every performance index at the steady state.

• Journal of radiological science and technology
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• v.28 no.4
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• pp.267-272
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• 2005

The effects of As addition in amorphous selenium (a-Se) films for digital X-ray conversion material have been studied using the moving photocarrier grating (MPG) technique. This method utilizes the moving interference pattern generated by the superposition of the two frequency shifted laser beams for the illumination of the sample. This moving intensity grating induces a short circuit current, jsc in a-Se:As film. The transport parameters of the sample are extracted from the grating-velocity dependent short circuit current induced in the sample along the modulation direction. The electron and hole mobility, and recombination lifetime of a-Se films with arsenic (As) additions have been obtained. We have found an increase in hole drift mobility and recombination lifetime, especially when 0.3% As is added into a-Se film, whereas electron mobility decreases with As addition due to the defect density. The transport properties for As doped a-Se films obtained by using MPG technique have been compared with X-ray sensitivity for a-Se:As device. The fabricated a-Se(0.3% As) device film exhibited the highest X-ray sensitivity out of 5 samples.

• Journal of the Korean Vacuum Society
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• v.2 no.2
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• pp.227-235
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• 1993

$SbS_{1-x}Se_xI,\;BiS_{1-x}Se_xI,\;Sb_{1-x}Bi_xSI,\;Sb_{1-x}Bi_xSeI,\;SbS_{1-x}Se_xI:Co,\;BiS_{1-x}Se_xI:Co,\;Sb_{1-x}Bi_xSI:Co$, and $Sb_{1-x}Bi_xSeI:Co$ single crystals were grown by the vertical Bridgman method using the ingots. It has been found that these single crystals have an orthorhombic structure and indirect optical transition. The composition dependences of energy gaps are given by $E_g(x)=E_g(0)-Ax+Bx^2$. The impurity optical absorption peaks due to cobalt deped with impurity are attributed to the electron transitions between the split energy levels of $Co^{2+}$ and $Co^{3+}$ ions sited at $T_d$symmetry of the host lattice.

• Journal of the Korean Chemical Society
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• v.63 no.5
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• pp.335-341
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• 2019

Spirulina was cultured in Selenium solution and the total concentration was determined with isotope dilution technique. Low-molecular-weight-Selenium species for the water extract of Spirulina were separated and quantified with HPLC ICP/MS. Water extraction was used first and then protein enzyme (protease XIV) was used to digest and extract for the Se species in both water extract and residue. The total Se was $414.9{\pm}4.0{\mu}g\;g^{-1}$ and 77% existed in water extract while 22% remained in residue. Se species in supernatant was mostly inorganic selenate ($222.7{\mu}g\;g^{-1}$). After hydrolysis of protein, SeCys ($15.20{\mu}g\;g^{-1}$) and SeMet ($12.13{\mu}g\;g^{-1}$) were found. In residue, SeCys and SeMet were found with little inorganic Se. After protein hydrolysis of residue, more of Selenoamino acids SeCys ($9.35{\mu}g\;g^{-1}$) and SeMet ($18.23{\mu}g\;g^{-1}$) in addition to MeSeCys ($1.5{\mu}g\;g^{-1}$) were found. It is thought that inorganic selenium is mostly adsorbed on the surface of spirulina and can be easily removed by a simple distilled water extraction while most of organo-seleniums are remained in residue.

• Asian-Australasian Journal of Animal Sciences
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• v.22 no.12
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• pp.1661-1666
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• 2009

The objective of this study was to determine the effect of Se-enriched bean sprout, Se-enriched yeast and sodium selenite on productivity, egg quality and egg Se concentrations in laying hens. Using a Completely Randomized Design, 144 Rohman laying hens at 71 weeks of age were divided into four groups. Each group consisted of four replicates and each replicate contained nine hens. The dietary treatments were T1: control diet, T2: control diet plus 0.3 mg Se/kg from sodium selenite, T3: control diet plus 0.3 mg Se/kg from Se-enriched yeast, T4: control diet plus 0.3 mg Se/kg from Se-enriched bean sprout. The results showed that there was no significant difference (p>0.05) in feed intake, egg production and egg quality among treatments. Selenium supplementation from Seenriched yeast and Se-enriched bean sprout markedly increased (p<0.05) egg Se concentration as compared to the control and sodium selenite groups. The results indicated that Se-enriched bean sprout could be used as an alternative Se source in diets of laying hens.

• Current Photovoltaic Research
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• v.7 no.4
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• pp.103-110
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• 2019

Cu(In,Ga)₃Se₅ (β-CIGS) has a band gap of 1.35 eV, which is an optimum value for high solar-energy conversion efficiency. The effects of Cu and Ga content on the cell performance were investigated previously. However, the effect of Se content on the cell performance is not well understood yet. In this work, β-CIGS films were fabricated by three-stage co-evaporation of elemental sources with various Se fluxes at the third stage instead of at all stages. The average composition of five samples was Cu_1.05(In_0.59,Ga_0.41)3Se_y, where the stoichiometric y value is 5.03 and the stoichiometric Se/metal (Se/M) ratio is 1.24. We varied the Se/metal ratio in a range from 1.18 to 1.28. We found that the best efficiency was achieved when the Se/M ratio was 1.24, which is exactly the stoichiometric value where the CIGS grains on the CIGS surface were tightly connected and faceted. With the optimum Se/M ratio, we were able to enhance the cell efficiency of a β-CIGS solar cell from 9.6% to 12.0% by employing a Na₂S post deposition treatment. Our results indicate that Na₂S post deposition treatment is very effective to enhance the cell efficiency to a level on par with that in α-CIGS cell.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.10
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• pp.2273-2279
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• 2012

This research is based on fabricating Cu(In,Ga)$Se_2$ thin-film by co-evaporation method. On $1^{st}$ - stage, $In_2Se_3$ phase appeared when the substrate temperature reached to $400^{\circ}C$, however, there was small effect between the substrate temperature and absorbency spectrum on $2^{nd}$, $3^{rd}$ - stage because the average thickness of the thin-film was $1{\mu}m$ or higher. SEM and XRD was measured on $2^{nd}$ and $3^{rd}$ stage and it showed as the substrate temperature increases, the density of the crystal structure increased with the decreament of the vacancy. Furthermore, the formation of Cu(In0.7Ga0.3)$Se_2$ phase showed at $480^{\circ}C$ and $500^{\circ}C$.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.11a
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• pp.76-77
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• 2005

Single crystal $CuAlSe_2$ layers were grown on thoroughly etched semi-insulating GaAs(100) substrate at 410$^{\circ}C$ with hot wall epitaxy (HWE) system by evaporating $CuAlSe_2$ source at $680^{\circ}C$. The crystalline structure of the single crystal thin films was investigated by the photoluminescence(PL) and double crystal X-ray diffraction (DCXO). The temperature dependence of the energy band gap of the $CuAlSe_2$ obtained from the absorpt ion spectra was wel1 described by the Varshni's relation, $E_g$(T) = 2.8382 eV - ($8.86\times10^{-4}$ eV/H)$T_2$/(T + 155K). After the as-grown single crystal $CuAlSe_2$ thin films were annealed in Cu-, Se-, and Al-atmospheres, the origin of point defects of single crystal $CuAlSe_2$ thin films has been investigated by PL at 10 K. The native defects of $V_{cd}$, $V_{se}$, $Cd_{int}$, and $Se_{int}$ obtained by PL measurements were classified as donors or acceptors. And we concluded that the heat-treatment in the Cu-atmosphere converted single crystal $CuAlSe_2$ thin films to an optical n-type. Also. we confirmed that hi in $CuAlSe_2$/GaAs did not form the native defects because Al in single crystal $CuAlSe_2$ thin films existed in the form of stable bonds.

• Journal of the Korean Electrochemical Society
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• v.14 no.3
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• pp.145-151
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• 2011

ZnSe, as a II-VI compound semiconductor which has a wide band gap in the visible region is applicable to the various fields such as laser diode, display and solar cell. By using the electrochemical deposition method, ZnSe thin film was synthesized on the ITO glass substrate. The synthesis of ZnSe grains and their structure having zinc blende shape were verified through the analysis of XRD and SEM. UV spectrophotometric method determined the band gap as the value of 2.76 eV. Applying the DFT (Density Functional Theory) in the molecular dynamics, the band structure of ZnSe grains was analyzed. For ZnSe grains with zinc blende structure, the band structure and its density of state were simulated using LDA (Local Density Approximation), PBE (Perdew Burke Ernzerhof), and B3LYP (Becke, 3-parameter, Lee-Yang-Parr) functionals. Among the calculations of energy band gap upon each functional, the simulated one of 2.65 eV based on the B3LYP functional was mostly near by the experimental measurement.