• Progress in Superconductivity and Cryogenics
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• v.23 no.2
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• pp.6-9
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• 2021

Heterostructures fabricated by various combinations of van der Waals (vdW) materials enable us to investigate disorder-free physical properties and realize novel functional devices. Superconducting vdW junctions have attracted a lot of attention because of its simple structure without a barrier layer. In superconducting vdW junction, without extra fabrication effort, a natural barrier can be formed, whose character is sensitive to distance and angle of lattice between two superconducting vdW materials. Using high-quality single crystals and the dry transfer technique, we fabricated the vertically stacked NbSe₂/NbSe₂ and FeSe/FeSe vdW junctions and investigated their Josephson junction properties. We found that in the FeSe junctions, Josephson coupling is extremely sensitive to the fabrication conditions, in contrast to the NbSe₂ junctions. We attributed this distinct character of the FeSe junctions to surface instability and small Fermi surface of FeSe.

• Current Photovoltaic Research
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• v.10 no.2
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• pp.39-48
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• 2022

A Se-containing Cu/SnSe₂/ZnSe precursor was employed to introduce S to the precursor to form Cu₂ZnSn(S,Se)₄ (CZTSSe) film. The morphology of CZTSSe films strongly varied with two different pre-annealing environments: S and N₂. The CZTSSe film with S pre-annealing showed a dense morphology with a smooth surface, while that with N₂ pre-annealing showed a porous film with a plate-shaped grains on the surface. CuS and Cu₂Sn(S,Se)₃ phases formed during the S pre-annealing stage, while SnSe and Cu₂SnSe₃ phases formed during the N₂ pre-annealing stage. The SnSe phase formed during N₂ pre-annealing generated SnS₂ phase that had plate shape and severely aggravated the morphology of CZTSSe film. The power conversion efficiency of the CZTSSe solar cell with S pre-annealing was low (1.9%) due to existence of Zn(S.Se) layer between CZTSSe and Mo substrate. The results indicated that S pre-annealing of the precursor was a promising method to achieve a good morphology for large area application.

• Journal of the Korean Vacuum Society
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• v.3 no.2
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• pp.203-206
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• 1994

동시증착법으로 성장한 CuIn3Se5 박막의 구조 및 광학적 특성을 XRD, SEM 광투과 및 광반사 측정으로부터 조사하였다. XRD 측정에 의하면 CuIn3Se5 는 정열된 Cu 빈자리와 Cuqls자리에 in으로 대 치되는 defect chalcopyrite 구조임이 확인디었다. 또한 광흡수 측정으로부터 CuIn3Se5 는 금지대내에서 직접 전이에 의한 광흡수 특성을 보여주며 이때 에너지띠 간격은 1.27ev 이었다. CuIn3Se5 박막에 대한 연구결과들은 CuInSe2 의 결과들과 비교하여 논의하였다.

• Proceeding of EDISON Challenge
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• 2017.03a
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• pp.468-472
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• 2017

2차원 InSe 단일층에 존재할 수 있는 vacancy defect인 In vacancy, Se vacancy의 원자구조 및 전자구조 특성을 제일원리계산을 이용해 살펴보았다. InSe $5{\times}5$ supercell을 이용하였으며 total energy를 구해 어떤 구조가 가장 안정한지 찾았다. Relax된 결함구조들을 clean InSe와 비교하여 어떤 변화가 있었는지 특징을 분석하였다. 이러한 intrinsic 결함들이 각각 어떤 구조로 relaxation되는지 살펴보고 clean InSe와 비교해보았다. 또한 각 결함구조의 density of states (DOS), projected density of states (PDOS)와 band structure를 clean InSe와 비교해봄으로써 defect state가 어떻게 나타나는지를 찾아보았다.

• Journal of the Korean Society of Food Science and Nutrition
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• v.23 no.3
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• pp.429-435
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• 1994

The effect of methionine (Met) supplementation on glutathione peroxidase(GSHPx) activity in young and 14 month-old rat and mice was investigated. GSHPx activity was more enhanced by methionine supplementation in young rats when selenium (Se) was given as selenite than given in the form of selenomethione (Se-Met). However, GSHPx activity was not influenced by Met supplementation in the old rats. When diets were low in Se, the biopotency of ht eenzyme by Met was facilitated. No significant differences in GSHPx activity was observed with Met supplement in growing mice when Met was given 0.3% and 0.8% iin the diet at high levels of Se (2 ppm). The peak GSHPx in liver and kidney occurred at day 18, thereafter it decreased. Particularly, the liver GSHPx at day 18 increased 4.2 times than that at day 4 by 0.5% Met supplementation, while the unsupplemented group remained only 2.5 times increase. It is considered that in some tissues Met requirement may be met by Se-Met when rats were fed a diet suboptimal in Met. In addition, at lower levels of Se the utilization of Se is more enhanced by Met than at higher levels of dietary Se. Therefore, GSHPx activity may be influenced greatly by Met status along with dietary Se.

• Journal of the Korean Vacuum Society
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• v.21 no.3
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• pp.136-141
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• 2012

We report investigation of structural and optical characteristics of $In_2Se_3$ thin films fabricated by thermal annealing process. Indium (In) is deposited on substrates by sputtering methods and $In_2Se_3$ thin films are fabricated by thermal annealing it with selenium vapor. The annealing temperature was changed from $150^{\circ}C$ to $400^{\circ}C$. We observe formation and phase changes of $In_2Se_3$ thin films with increase of annealing temperature. Conglomeration of In is observed at low annealing temperature (${\leq}150^{\circ}C$). $In_2Se_3$ phases are started to form at $200^{\circ}C$ and ${\gamma}-In_2Se_3$ phase form at $350^{\circ}C$. High-quality ${\gamma}-In_2Se_3$ thin film with wurtzite structure is obtained at $400^{\circ}C$ of annealing temperature. Furthermore, we confirm that band gaps of $In_2Se_3$ thin films are increased according to increase of annealing temperature. Optical band gap of high-quality ${\gamma}-In_2Se_3$ is found to be 1.796eV.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.18 no.1
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• pp.79-84
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• 2018

This paper relates with the performance improvement of SE-MMA (Signed Error-Multiple Modulus Algorithm) adaptive equalization algorithm that is used for the reduction of the intersymbol interference due to the distortion which occurs in the communication channel for the transmission of 16-QAM nonconstant modulus signal.. In the conventional MMA, the fixed modulus value that is second order statistics of transmitting signal were used, and the SE-MMA was introduced in order to the simplification of the algorithm's arithmetic operation. The SE-MMA have a fast convergence speed than MMA, but it has a problem of degradation of equalization performance in the steady state due to the arithmetic simplification. In this paper, we propose the new algorithm AV-SE-MMA (Adaptively Varying-SE-MMA) that uses the adaptive varying modulus in order to obtain the error signal for updating the adaptive equalizer coefficient, and its equalization performance were confirmed by simulation. In this paper, the performance of SE-MMA and proposed algorithm were compared, and the equalizer output signal constellation, residual isi, MSE and SER in order to confirm the robustness of noise were used as performace index. As a result of performance comparison, the AV-SE-MMA has better performance in output signal constellation, residual isi and MD compared to the SE-MMA, but it was confirmed that the AV-SE-MMA has similar in the SER performance that means the robustness to the noise.

• Asian-Australasian Journal of Animal Sciences
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• v.19 no.7
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• pp.984-991
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• 2006

Effects of spent composts of selenium-enriched mushroom (Se-SMC) on plasma glutathione peroxidase (GSH-Px) activity and selenium (Se) deposition in finishing Hanwoo (Bos taurus coreanae) steers were investigated. Twenty-five Hanwoo steers (average body weight = 613 kg, average age = 22 months) were allotted to treatments in five groups of five steers per pen for 12 weeks preceding slaughter. Treatments were SMC alone (CON; 0.1 ppm Se), 0.3 ppm (0.3 Se-SMC), 0.6 ppm (0.6 Se-SMC), 0.9 ppm (0.9 Se-SMC), and 0.9 ppm (sodium selenite; SENI) Se. During the experimental period, blood samples were taken to analyze Se concentrations and GSH-Px activities. Muscle and liver samples were collected for analyses of Se contents after slaughter. Dry matter intake and body weight gain were not affected by Se-SMC or sodium selenite supplementation. Selenium concentration in the whole blood and GSH-Px activity in plasma were linearly increased (p<0.01) with increasing levels of Se-SMC. The whole blood Se concentration of SENI treatment was significantly higher (p<0.05) than that of CON treatment from 4 weeks, whereas there was no significant difference in GSH-Px activities between both treatments at 8 and 12 weeks. Selenium content in the hind leg and liver increased linearly (p<0.05) with increasing levels of Se-SMC, but those of SENI treatments were not significantly different from CON treatments. These results suggested that Se in the Se-SMC was highly bioavailable to blood and tissues of ruminants, especially compared with Se in the sodium selenite. Therefore, Se-SMC might be used not only as an inexpensive way of providing Se for ruminants but also as another way of producing Se-fortified beef.

• Food Science of Animal Resources
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• v.22 no.2
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• pp.108-114
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• 2002

The effects of dietary vitamin E and selenium(Se) supplementation on meat color stability in M. Longissimus of Hanwoo(Korean native cattle) bull beef during retail display(5$^{\circ}C$, 1,200 lux) were investigated. Experimental groups were divided into control(Vit E 27 IU/head/day, Se 0.09 mg/head/day), Vit E (2,500 IU/head/day), Se(20 mg/head/day), Vit E+Se(Vit E 2,500 IU/head/day, Se 20 mg/head/day) groups. CIE a*(redness), chroma(C*) values, oxymyoglobin(%) and R630-R580 were significantly (p<0.05) decreased among the 4 treatment groups during retail display, in particular, those values decreased more rapidly in the control group. The metmyoglobin (%) of 0 day(before storage) was not significantly (p<0.05) different among the 4 treatment groups. However, the rate of metmyoglobin accumulation during storage increased more rapidly in the control group. Therefore, discoloration in the control group was more accelerated compared to the other groups. TBARS(thiobarbituric acid reactive substances) which represent lipid rancidity was significantly(p<0.05) lower in Se and Vit E+Se groups than in the control and Vit E groups. Reducing ability of 0 day(before storage) was significantly lower in the control group than in the other groups, and it decreased more rapidly in the control group after 3 days of storage. Consequently, Se-supplemented groups(Se and Vit E+Se groups) were more resistant to lipid oxidation than were the control and Vit E groups. The stability of meat color and myoglobin forms(%) were significantly (p<0.05) higher in Vit E, Se and Vit E+Se groups than in the control group, but there were no difference among Vit E, Se and Vit E+Se groups.

• Journal of Embryo Transfer
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• v.30 no.3
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• pp.201-206
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• 2015

Selenium (Se) is an essential trace element for humans and animals, and several findings suggest that dietary Se intake may be necessary for bone health. Accumulating evidence indicates that Se compounds possess anticancer properties. Se is specifically incorporated into proteins in the form of selenocysteine and non-specifically incorporated as selenomethionine in place of methionine. This study evaluated protection by Se in the bone repair process in ovariectomized rats after irradiation. For such purpose, 80 ovariectomized female Sprague-Dawley rats were randomly divided into 4 experimental groups: ovariectomized (Ov), Ov/Se, Ov/irradiated (Irr) and Ov/ Se/Irr. A bone defect was created on the tibia of all animals 40 days after ovariectomy. Two days after surgery, only the Ov/Se and Ov/Se/Irr rats received 0.8 mg Se/kg. Three days after surgery, only the Ov/Irr and Ov/Se/Irr rats received 10 Gy of X-rays on the lower limb region. The animals were euthanized at 7, 15, 22 and 29 days after surgery to assess the repair process, which was evaluated by analysis of trabecular bone number (Masson Trichrome) and birefringence analysis (Picrosirius). It was possible to observe a delay in the bone repair process in the ovariectomized/irradiated group and similarity between the ovariectomized, Ov/ Se and Ov/Se/Irr groups. Our findings suggest that sodium selenite may influence a radioprotective effect in the bone repair of tibia of ovariectomized rats without toxicity.