• Applied Science and Convergence Technology
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• v.26 no.6
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• pp.189-194
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• 2017

Effects of gas injection scheme and rf driving current configuration in a dual turn inductively coupled plasma (ICP) system were analyzed by 3D numerical simulation using CFD-ACE+. Injected gases from a tunable gas nozzle system (TGN) having 12 horizontal and 12 vertical nozzles showed different paths to the pumping surface. The maximum velocity from the nozzle reached Mach 2.2 with 2.2 Pa of Ar. More than half of the injected gases from the right side of the TGN were found to go to the pump without touching the wafer surface by massless particle tracing method. Gases from the vertical nozzle with 45 degree slanted angle soared up to the hottest region beneath the ceramic lid between the inner and the outer rf turn of the antenna. Under reversed driving current configuration, the highest rf power absorption region were separated into the two inner islands and the four peaked donut region.

• Applied Science and Convergence Technology
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• v.26 no.6
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• pp.214-217
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• 2017

AlSb is a promising material for optical devices, particularly for high-frequency and nonlinear-optical applications. We report the effect of growth temperature on structural properties of AlSb grown on GaAs substrate. In particular we studied the surface of AlSb with the growth temperature by atomic force microscopy, and concluded that optimized growth temperature of AlSb is $530^{\circ}C$. We also show the result of real-time monitoring of AlSb growth by in situ ellipsometry. The results of the structural study are good agreement with the previous reported ellipsometric data.

• Applied Science and Convergence Technology
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• v.27 no.4
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• pp.61-64
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• 2018

The basic principle and concept for hydrogen production via water-splitting process are introduced. In particular, recent research activities and their progress in the photoelectrochemical water-splitting process are investigated. The material perspectives of semiconducting photocatalysts are considered from metal oxides, including titanium oxides, to carbon compounds and perovskites. Various structural configurations, from conventional photoanodes with metal cathodes to tandem and nanostructures, are also studied. The pros and cons of each are described in terms of light absorption, charge separation/photoexcited electron-hole pair recombinations and further solar-to-hydrogen efficiency. In this research, we attempt to provide a broad view of up-to-date research and development as well as, possibly, future directions in the photoelectrochemical water-splitting field.

• Applied Science and Convergence Technology
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• v.27 no.4
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• pp.75-77
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• 2018

The electrostatic interaction between emerging quantum-confined nanostructures with plasmonic structures is crucial for future biological applications. Water-soluble green fluorescent copper nanoparticles (Cu-NPs) were fabricated. We demonstrate that L-ascorbic acid is considered as a key to precisely control small Cu-NPs and the capability of the surface ligands, while cetyltrimethylammonium bromide is used as a stabilizing agent controls the particle growth, and stabilizes the nanoparticles. Water-soluble green fluorescent Cu-NPs are tunable through modification of the reaction periods.

• Applied Science and Convergence Technology
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• v.27 no.5
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• pp.79-85
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• 2018

Many studies have been conducted on large-scale graphene synthesis by chemical vapor deposition. Furthermore, numerous researchers have attempted to develop processes that can continuously fabricate uniform and high-quality graphene. To compete with other types of carbon materials (carbon black, carbon fiber, carbon nanotubes, and so on), various factors, such as price, mass manufacturing capability, and quality, are crucial. Thus, in this study, we examine various large-scale graphene production methods focusing on cost competitiveness and productivity improvements for applications in various fields.

• Applied Science and Convergence Technology
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• v.27 no.5
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• pp.86-89
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• 2018

Observations of neutrino oscillations are very strong evidence for the existence of neutrino masses and mixing. From recent experimental results on neutrino oscillation, we find that neutrino mixing angles are quite consistent with the so-called tri-bi-maximal mixing pattern, but the deviation from observational results is non-negligible. However, the tri-bi-maximal mixing pattern is still useful as a leading order approximation and provides a good guideline to search for the flavor symmetry in the neutrino sector. We introduce the $S_4$ permutation symmetry as a flavor symmetry to the standard model of particle physics with additional particle contents of heavy right-handed neutrinos and scalar fields. Finally, we obtain the tri-bi-maximal mixing pattern as a mixing matrix in the lepton sector within the suggested model. To derive the required unitary mixing matrix for the neutrino sector, the double seesaw mechanism is utilized.

• Applied Science and Convergence Technology
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• v.27 no.5
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• pp.105-108
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• 2018

Transparent $TiO_2$ nanotube arrays are successfully prepared by a two-step approach involving electrochemical anodization and RF magnetron sputtering. First, a Ti film is deposited on an FTO substrate by RF magnetron sputtering at room temperature. The morphologies of the Ti film are controlled by the working distance, Ar flow, and DC power. Second, an anodization treatment is electrochemically performed for the formation of nanotube arrays from the deposited Ti film, followed by post-annealing treatment in air for the formation of $TiO_2$ crystallization. The back side of the crystallized $TiO_2$ nanotube arrays is illuminated with solar light to characterize the photoelectrochemical reaction, and their photoelectrochemical properties are investigated. This work provides information on application of a thin film deposited by RF sputtering in the field of photoelectrochemical water splitting.

• Journal of Animal Science and Technology
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• v.62 no.2
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• pp.263-275
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• 2020

Studies on promoting milk protein yield by supplementation of amino acids have been globally conducted. Nevertheless, there is a lack of knowledge of what pathways affected by individual amino acid in mammary epithelial cells that produce milk in practice. Phenylalanine (PHE) and valine (VAL) are essential amino acids for dairy cows, however, researches on mammary cell levels are still lacking. Thus, the aim of this study was conducted to evaluate the effects of PHE and VAL on milk protein synthesis-related and energy-mediated cellular signaling in vitro using immortalized bovine mammary epithelial (MAC-T) cells. To investigate the effects of PHE and VAL, the following concentrations were added to treatment medium: 0, 0.3, 0.6, 0.9, 1.2, and 1.5 mM. The addition of PHE or VAL did not adversely affect cell viability compared to control group. The concentrations of cultured medium reached its maximum at 0.9 mM PHE and 0.6 mM VAL (p < 0.05). Therefore, aforementioned 2 treatments were analyzed for proteomics. Glucose transporter 1 and mammalian target of rapamycin mRNA expression levels were up-regulated by PHE (166% and 138%, respectively) (p < 0.05). Meanwhile, sodium-dependent neutral amino acids transporter type 2 (ASCT2) and β-casein were up-regulated by VAL (173% in ASCT2, 238% in and 218% in β-casein) (p < 0.05). A total of 134, 142, and 133 proteins were detected in control group, PHE treated group, and VAL treated group, respectively. Among significantly fold-changed proteins, proteins involved in translation initiation or energy metabolism were detected, however, expressed differentially between PHE and VAL. Thus, pathway analysis showed different stimulatory effects on energy metabolism and transcriptional pathways. Collectively, these results showed different stimulatory effects of PHE and VAL on protein synthesis-related and energy-mediated cellular signaling in MAC-T cells.

• Applied Science and Convergence Technology
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• v.24 no.5
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• pp.184-189
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• 2015

We report a simple way to enhance the size gradient of an imprinted nanopattern through oxygen plasma etching under a nonuniform magnetic field. A sample substrate was placed next to a magnet, and then a nonuniform magnetic field condition was formed around the sample. Using oxygen plasma etching, a line pattern having an initial width of 273 nm was gradually modified from 248 nm at one end to 182 nm at the other end. Controlling the arrangement of the magnet and sample, we could induce a triangular shape size gradient. We verified that the gradually modified nanopatterns we produced are applicable to continual optical property control, showing a possibility to be utilized for optical components such as gratings and polarizers.

• Applied Science and Convergence Technology
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• v.24 no.5
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• pp.125-131
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• 2015

We investigated the thermal characteristics of rotating anode X-ray tube to develop it for digital radiography by using computer simulation. The target which is the area of the anode struck by electrons is the most important component to get a long life of X-ray tube. So we analyze the thermal characteristics of the target and rotor assembly according to their emissivity by using ANSYS transient thermal simulation and then compare with the measured data of the target temperature operating in aging process of X-ray tube. Especially, keeping the lead coated layer as the role of metal lubricant on ball bearing enables to prevent the noise in rotating anode. The simulation result showed that its temperature was under the melting point of the lead in X-ray tube for digital radiography with 1.2 mm large focal spot 0.6 mm small focal spot and 150 kV tube voltage. We also investigated the relationship between the diameter of the anode shaft and the temperature of the anode and rotor assembly. It has been confirmed that the smaller anode shaft could be good for the rotor thermal characteristics.