• JSTS:Journal of Semiconductor Technology and Science
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• 제3권1호
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• pp.21-26
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• 2003

4H-SiC Schottky rectifiers were exposed to pure Ar discharges in a planar coil Inductively Coupled Plasma system, as a function of source power, of chuck power and process pressure. The reverse breakdown voltage ($V_B$) decreased as a result of plasma exposure due to the creation of surface defects associated with the ion bombardment. The magnitude of the decrease was a function of both ion flux and ion energy. The forward turn-on voltage ($V_F$), on-state resistance ($R_{ON}$) and diode ideality factor (n) all increased after plasma exposure. The changes in all of the rectifier parameters were minimized at low power, high pressure plasma conditions.

• Proceedings of the Korean Vacuum Society Conference
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• 한국진공학회 1996년도 제10회 학술발표회 논문개요집
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• pp.102-102
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• 1996

This paper represents a new type low power High Frequency technological ion source (HF TIS) for ion - beam processing: the surface modification of materials, cleaning of surface, sputtering, coating of thin films, and polishing. The operational principle of HF TIS is based on the excitation of electrostatic waves in plasma located in the external magnetic field. Low power HF TIS with diameter 92 rom gives the opportunity to obtain beams of inert and chemically reactive gases with currents range from 5 to 150 mA (current density $0.015\;~\;3.5\;mA/\textrm{m}^2$) and ion beam energy 100 ~ 2500 eV at a HF power level 10 ~ 150 W. Three grid concave type ion optical system (IOS) is used for extraction and formation ofion beam.n beam.

• Journal of Magnetics
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• 제16권2호
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• pp.124-128
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• 2011

This study estimated experimentally the loss distribution caused by magnetic friction in magnetic parts of a superconductor flywheel energy storage system (SFES) to obtain information for the design of high efficiency SFES. Through the spin down experiment using the manufactured vertical shaft type SFES with a journal type superconductor magnetic bearing (SMB), the coefficients of friction by the SMB, the stator core of permanent magnet synchronous motor/generator (PMSM/G), and the leakage flux of the metal parts were calculated. The coefficients of friction by the stator core of PMSM/G in case of using Si-steel and an amorphous core were calculated. The energy loss by magnetic friction in the stator core of PMSM/G was much larger than that in the other parts. The level of friction loss could be reduced dramatically using an amorphous core. Energy loss by the leakage magnetic field was small. On the other hand, the energy loss could be increased under other conditions according to the type of metal nearby the leakage magnetic fields. In manufactured SFES, the rotational loss by the amorphous core was approximately 2 times the loss of the superconductor and leakage. Moreover, the rotational loss by the Si-steel core is approximately 3~3.5 times the loss of superconductor and leakage.

• Journal of the Korean Solar Energy Society
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• 제33권3호
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• pp.75-81
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• 2013

In this study, we analyze the performance characteristics of Building Integrated Photovoltaic (BIPV) system of K Research Building which was designed with the aim of zero carbon building. In addition, BIPV system, which is consist of three modules; G to G(Glass to Glass), G to T(Glass to Tedlar/Crystal) and Amorphous, has 116.2kWp of total capacity, and is applied to wall, window, atrium and pagora on roof. Therefore, in this paper, our research team analyzed BIPV yield and generation characteristic. BIPV yield was 112,589kWh a year from January 2012 to December 2012. And after applying PV panels on the building, the power from the best setting angle, $30^{\circ}$, of panel was compared. In addition, when the PV was attached practically on the building, the generation power was analyzed. BIPV modules in this study the relationship between module setting angle, type of modules ect. and power characteristics plans to identify.

• The Korean Journal of Food And Nutrition
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• 제31권6호
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• pp.821-827
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• 2018

Ecklonia cava which is a kind of phaeophyta and belongs to Laminariales Alariaceae is a perennial seaweed distributed over Jeju and Dokdo islands. The purpose of this study evaluate antioxidant activities of Ecklonia cava crackers. Crackers were prepared with different measurements (0, 2, 4, 6, 8 g) of Ecklonia cava; indicated as S1, S2, S3, S4 and S5, and are used to examine and compare antioxidant activities, and quality characteristics. Ecklonia cava powder was used, after being extracted with 70% ethanol in hot water and done in freeze dehydration. To examine antioxidant activities of Ecklonia cava and cracker, DPPH radical scavenging activity, total phenolic and reducing power were tested. Total phenolic content was 36.86 mg GAE/g. DPPH radical scavenging activity and reducing power showed good vitality as amounts of Ecklonia cava powder increased (p<0.001). pH level decreased as amounts of power increased. L (lightness) values and b (yellowness) values decreased with an increased concentration of Ecklonia cava powder (p<0.001), whereas (redness) values didn't show tendency. S5 indicated the lowest spreadness. According to sensory evaluation, S4 (6 g) was preferred the most in terms of color, flavor, taste, appearance, texture, and overall palatability. Results suggest that Ecklonia cava powder has antioxidant effect and is useful as a functional food resource.

• International journal of advanced smart convergence
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• 제10권3호
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• pp.17-25
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• 2021

As a new paradigm in non-orthogonal multiple access (NOMA), correlated superposition coding (CSC) has gained an attention in the literature of NOMA, in contrast to standard independent superposition coding (ISC). In the conventional 3-user CSC scheme, it has been reported that the average allocated power can be reduced, owing to an introduced correlation between transmitted signals. Thus, this paper proposes a 3-user cross CSC scheme with purely-imaginary correlation coefficients. First, we derive the achievable data rates of the proposed 3-user cross CSC scheme, for each of the three users. Then, simulations demonstrate that for the proposed 3-user cross CSC scheme, the achievable data rates of the first and second users increase greatly and slightly, respectively, whereas the achievable data rate of the third user decreases little, compared to those of the conventional 3-user CSC scheme. In addition, we also show that the sum rate of the three users of the proposed 3-user cross CSC scheme is much larger than that of the three users of the conventional 3-user CSC scheme. As a result, the proposed 3-user cross CSC scheme could be a solution to the problem of the reduction of the average allocated total power in the conventional 3-user CSC scheme toward the fifth-generation (5G) NOMA mobile networks.

• Progress in Superconductivity and Cryogenics
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• 제11권2호
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• pp.15-19
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• 2009

Bulk $YBa_2Cu_3O_{7-{\delta}}$ (YBCO) superconductor was manufactured with the top-seeded melt grown method. The 9, 16, and 25 holes, as small as 0.7mm in diameter, parallel to the c-axis were mechanically drilled. Magnetic flux mapping and levitation force were measured and compared to estimate the influence of multiple holes on the magnetic properties of YBCO superconductor at 77K. According to the measurements, the maximum magnetic flux density obtained from the plain sample was 2.48kG, while the maximum magnetic flux density of the sample with 25 holes was low as around 2.29kG. The levitation force measured on the sample with 9 holes increased from 91N to 105N. The levitation force measured on the samples with 9 holes is relatively higher than the plain sample without any holes. In this case, increase of the levitation force in the perforated samples could be explained by enhancement of the cooling efficiency more effectively. We investigated that the magnetic properties of YBCO superconductor were strongly influenced by the artificial holes.

• Bulletin of the Korean Chemical Society
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• 제28권1호
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• pp.33-40
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• 2007

We have designed and synthesized three Zn(II)-porphyrin derivatives, such as Zn(II) porphyrin ([G-0]Zn-P1) and aryl ether-typed dendron substituted Zn(II)-porphyrin derivatives ([G-1]Zn-P1 and [G-1]Zn-P-CN1). Their chemical structures were characterized by 1H-NMR, FT-IR, UV-vis absorption, EI-mass, and MALDI-TOF mass spectroscopies. Their electrochemical properties were studied by cyclic voltammetry measurement. These Zn(II)-porphyrin derivatives have been used to fabricate dye-sensitized solar cells (DSSCs) based on solid polymeric electrolytes as dye sensitizers and their device performances were evaluated by comparing with that of a standard Ru(II) complex dye. [G-1]Zn-P-CN1 showed the enhanced power conversion efficiency than those of other porphyrin derivatives, as expected. Short-circuit photocurrent density (Jsc), open-circuit voltage (Voc), fill factor (FF), and power conversion efficiency (η) of solid-typed DSSC for [G-1]Zn-P-CN1 were evaluated to be Jsc = 11.67 mA/cm2, Voc = 0.51 V, FF = 0.46, and η = 2.76%, respectively.

• The Korea Journal of Herbology
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• 제30권2호
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• pp.31-36
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• 2015

Objectives : In this study, we demonstrated the antioxidant activities and the inhibitory effect on oxidative DNA damage of ethyl acetate fractions extracted from Sophorae Flos and Sophorae fructus. Methods : Sophorae Flos and Sophorae fructus were extracted with methanol(MeOH) and divided to Petroleum ether, Ethyl acetate(EtOAC) and Water fraction. The antioxidant activities were conducted by the 1,1-diphenyl-2-picryl hydrazyl(DPPH) radical, 2, 2'-Azine-bis(3-ethylbenzothiazoline-6 sulfonic acid) diammonium salt(ABTS) radical scavenging assay, $Fe^{2+}$ chelating assay and Reducing power assay. The inhibitory effect of DNA damage were characterized on ${\varphi}$ X-174 RF I plasmid DNA cleavage assay. In addition, we analyzed the Total phenol contents and the Vitamin C contents of Sophorae Flos and Sophorae fructus. Results : The results of DPPH were 92.71% and 94.72%, ABTS were 87.16% and 62.44%, and $Fe^{2+}$ chelating were 95.81% and 85.11% at $200{\mu}g/m{\ell}$ of Sophorae Flos and Sophorae fructus respectively. The Sophorae Flos showed stronger effect than Sophorae fructus in Reducing Power assay. Total phenol content was 111.77 mg/g and 122.54 mg/g, and Vitamin C content was 2.59 mg/g and 3.03 mg/g. Also both Sophorae Flos and Sophorae fructus have inhibitory antioxidant effect on ${\varphi}$ X-174 RF I plasmid DNA cleavage assay. Conclusions : Over all, this study suggests that Sophorae Flos and Sophorae fructus can be used as not only effective antioxidant but also natural medicine.

• Journal of Radiation Protection and Research
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• 제47권2호
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• pp.99-106
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• 2022

Background: The radionuclide inventory calculation codes such as ORIGEN and FISPACT collapse neutron reaction libraries with energy spectra and generate an effective one-group cross-section. Since the nuclear cross-section data, energy group (g) structure, and other input details used by the two codes are different, there may be differences in each code's activation inventory calculation results. In this study, the calculation results of neutron-induced activation inventory using ORIGEN and FISPACT were compared and analyzed regarding radioactive waste classification and worker exposure during nuclear decommissioning. Materials and Methods: Two neutron spectra were used to obtain the comparison results: Watt fission spectrum and thermalized energy spectrum. The effective one-group cross-sections were generated for each type of energy group structure provided in ORIGEN and FISPACT. Then, the effective one-group cross-sections were analyzed by focusing on ⁵⁹Ni, ⁶³Ni, ⁹⁴Nb, ⁶⁰Co, ¹⁵²Eu, and ¹⁵⁴Eu, which are the main radionuclides of stainless steel, carbon steel, zircalloy, and concrete for decommissioning nuclear power plant (NPP). Results and Discussion: As a result of the analysis, ¹⁵⁴Eu and ⁵⁹Ni may be overestimated or underestimated depending on the code selection by up to 30%, because the cross-section library used for each code is different. When ORIGEN-44g, -49g, and -238g structures are selected, the differences of the calculation results of effective one-group cross-section according to group structure selection were less than 1% for the six nuclides applied in this study, and when FISPACT-69g, -172g, and -315g were applied, the difference was less than 1%, too. Conclusion: ORIGEN and FISPACT codes can be applied to activation calculations with their own built-in energy group structures for decommissioning NPP. Since the differences in calculation results may occur depending on the selection of codes and energy group structures, it is appropriate to properly select the energy group structure according to the accuracy required in the calculation and the characteristics of the problem.