• Nuclear Engineering and Technology
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• v.54 no.11
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• pp.4310-4321
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• 2022

The concept of dense granular-flow target (DGT) for the China Initiative Accelerator Driven Subcritical system (CiADS) is an attractive choice for high heat removal ability, low chemical toxicity, and radiotoxicity. A wobbling hollow beam is proposed to enhance the homogeneity of temperature rise of flowing particles in beam-target coupling zone. In this paper, the design procedure of target and beam parameters was discussed firstly. Then we simulated the heat deposition and transfer of the scanning beam in DGT to study the effect of beam parameters. The results show the flux density of proton beam plays a crucial role in the distribution of temperature rise while the contributions from scanning frequency heat transfer are also obvious. Moreover, heat transfer in transversal directions is insignificant, resulting in a low heat flux towards the sidewalls of DGT. This work not only contributes to the design of DGT, but also beneficial for understanding the beam-target coupling in porous materials.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.26 no.3
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• pp.410-416
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• 2002

The fluid flow, heat transfer and the local mass fraction of chemical species in the chemical vapor deposition(CVD) manufacturing process are studied numerically. Flow with a dilute precursor concentration of silane in hydrogen as the carrier gas enters to the reactor and deposits silicon onto the heated surface. The silicon deposition rate using silane is calculated in the horizontal or vertical, axisymmetric reactor. The effects of inlet carrier gas velocity, mass fraction of silane, susceptor angle and rotation of surface on the deposition rate are described.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.20 no.2
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• pp.641-648
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• 1996

Thermophoretic particle deposition on a circular cylinder in a uniform laminar air flow was numerically investigated using a control volume method based on the generalized non-orthogonal coordinate system. Variation of air properties due to the change of temperature was taken into account. Effects of variable property on the distribution of heat transfer and deposition rates of particle were discussed. A new correlation of thermophoretic particle deposition on a circular cylinder was proposed in the present study.

• Journal of the Korean institute of surface engineering
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• v.18 no.3
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• pp.116-124
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• 1985

Chemical vapor deposition of $SnO_2$ on Pyrex glass substrate has been investigated using $SnCl_4$ and Oxygen at relatively low temperatures(300-500$^{\circ}C$). The critical flow rate, which delineated the surface reaction controlled region from the mass transfer controlled region, was increased with deposition temperature. The apparent activation energy obtained in surface reaction controlled region was about 6Kcal/mole. The results show that deposition rate, electrical conductivity and transmittance were affected mainly by partial pressure of $SnCl_4$, but little by partial pressure f oxygen. The % transmission of 5000A-thick $SnO_2$ film was about 90% in visible spectrum region and sheet resistance was varied in 0.1-10${\Omega}$ per square shaped portion of the outer surface of the oxide.

• Korean Journal of Materials Research
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• v.5 no.1
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• pp.140-148
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• 1995

Optical properties of $TiO_{2}$. Ag filrns and $TiO_{2}/Ag/TiO_{2}$ multilayer filrns with different thickness were predicted using the transfer matrix, and these results were compared with real transmittance curves of the sputterdeposited films. With the complex refractive indices, it was possible to predict transmittance characteristics which were close to real data for $TiO_{2}$ and Ag films. Due to the diffusion and agglomeration of Ag during $TiO_{2}$ deposition, optical properties of the sputterdeposited $TiO_{2}/Ag/TiO_{2}$ films were found to be very different from the transmittance curves predicted using the transfer matrix. Using deposition of 4nm-thick or 6nm-thick TI layers as a diffusion barrier, however, the transmittance curves of $TiO_{2}/Ti/Ag/Ti/TiO_{2}$ five-layer films became similar to ones predicted for $TiO_{2}/Ag/TiO_{2}$ threeiayer films.

• Korean Journal of Materials Research
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• v.32 no.12
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• pp.522-527
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• 2022

Among efforts to improve techniques for the chemical vapor deposition of large-area and high-quality graphene films on transition metal substrates, being able to reliably transfer these atomistic membranes onto the desired substrate is a critical step for various practical uses, such as graphene-based electronic and photonic devices. However, the most used approach, the wet etching transfer process based on the complete etching of metal substrates, remains a great challenge. This is mainly due to the inevitable damage to the graphene, unintentional contamination of the graphene layer, and increased production cost and time. Here, we report the systematic study of an H₂ bubbling-assisted transfer technique for graphene films grown on Cu foils, which is nondestructive not only to the graphene film but also to the Cu substrate. Also, we demonstrate the origin of the graphene film tearing phenomenon induced by this H₂ bubbling-assisted transfer process. This study reveals that inherent features are produced by rolling Cu foil, which cause a saw-like corrugation in the poly(methyl methacrylate) (PMMA)/graphene stack when it is transferred onto the target substrate after the Cu foil is dissolved. During the PMMA removal stage, the graphene tearing mainly appears at the apexes of the corrugated PMMA/graphene stack, due to weak adhesion to the target substrate. To address this, we have developed a modified heat-press-assisted transfer technique that has much better control of both tearing and the formation of residues in the transferred graphene films.

• Journal of Embryo Transfer
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• v.20 no.2
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• pp.157-162
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• 2005

To find out the possible inefficiencies of artificial inseminators at rectovaginal insemination in cows, inseminators' skill were evaluated by controlling the semen thawing procedure adopted and by using the technique of dye deposition in the genital tract of slaughtered cows. This was followed by refreshment training for the inseminators. Thirty seven artificial insemination technicians regularly working in the government, cooperative and NGO (Non Government Organization) artificial insemination programmes at different places of Bangladesh were included in the study. Individual technicians were asked to thaw a semen straw and deposit dye in the genital tract of slaughtered cows following the procedures they would have adopted in their actual practices of insemination. The time and water temperature adopted by technicians were recorded and genital tract after sham artificial insemination was dissected to determine the site of dye deposition. Then, the inseminators took part in a three days intensive training program. The training program was ended up with the same tests for thawing frozen semen straw and dye deposition in the genital tract of slaughtered cows. At pre training evaluation, only $25\%\;and\;72\%\;(n=36)$ inseminators adopted co..ect thawing time and temperature, respectively. At post training evaluation, all inseminators thawed semen straws for proper time and temperature. At pretraining evaluation, $21(57\%),\;11 (30\%)\;and\;3(8\%)$ inseminators deposited dye at the body of uterus, in the vagina or in cervix, and into the horn of uterus, respectively. In $2(5\%)$ cases dye did not pass into the genital tract, instead back flowed through the space between the barrel of insemination gun and sheath. At post training evaluation, all inseminators successfully deposited dye in the body of uterus. Frequent evaluation of inseminators' skill and subsequent training would help improvement of the artificial insemination technicians' skill.

• Journal of the Semiconductor & Display Technology
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• v.22 no.2
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• pp.1-5
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• 2023

In the past, display devices have undergone many changes, such as plasma TVs and LCDs, and have continued to develop. Recently, new display technologies, such as Organic Light Emitting Diode displays and Inorganic Light Emitting Diode displays, have been developed. Among them, Micro LED displays have the potential to improve performance more than LCDs and OLEDs, but a lot of effort and time are needed until the mass production technology (transfer and bonding) of Micro LED displays is developed. We have developed a new Micro LED display light source that can be produced using existing transfer and bonding process technologies to enable faster commercialization of Micro LED in the industry. This light source is TFT deposition on LED. TFT deposition on LED has the advantage of being able to produce displays using existing process technology, making early commercialization of display application products possible. In this study, we applied the Active Driving method to verify the performance of TFT deposition on LED as a display to determine its commercialization potential. Additionally, to facilitate faster application of Micro LED in the industry, we applied TFT deposition on LED to Optical Wireless Communication systems, which are widely used in application service areas such as safety/security and sensors, to verify its communication performance. The experimental results confirmed that TFT deposition on LED is not only capable of AM driving but can also be applied to OWC systems.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.33 no.10
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• pp.729-736
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• 2009

Pool boiling heat transfer and critical heat flux (CHF) of water-based nanofluids with alumina and titania nanoparticles of 0.01% by volume were investigated on a disk heater at saturated and atmospheric conditions. The experimental results showed that the boiling in nanofluids caused the considerable increase in CHF on the flat surface heater. It was revealed by visualization of the heater surface subsequent to the boiling experiments that a major amount of nanoparticles deposited on the surface during the boiling process. Pool boiling of pure water on the surface modified by such nanoparticle deposition resulted in the same CHF increases as what boiling nanofluids, thus suggesting the CHF enhancement in nanofluids was an effect of the surface modification through the nanoparticle deposition during nanofluid boiling. Possible reasons for CHF enhancement in pool boiling of nanofluids are discussed with surface property changes caused by the nanoparticle deposition.

• Proceedings of the KIEE Conference
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• 1996.07c
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• pp.1722-1724
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• 1996

Enhancing the electrical conductivity of the ultrathin organic films is one of the important factors for the development of molecular electronic devices. The Langmuir-Blodgett(LB) technique has recently been attracted as out of the ways of deposition ultrathin films. We have studied manufacturing conditions and physical properties of Hexadecyl Dipyridinium-$(TCNQ^-)_2$ LB films made by Kuhn type apparatus. A ${\pi}-A$ isotherm shows that a limiting area is around $180{\AA}^2/molecule$ and a proper surface pressure for a deposition is around 22mN/m. A transfer ratio shows that Hexadecyl Dipyridinium-$(TCNQ^-)_2$ is able to be deposited as an Y-type. UV /visible absorption spectra shows that TCNQ dimer peak is apeared at about 600nm in LB films. In solution, $TCNQ^-$ peak is observed at about 400nm and charge transfer band at $830{\sim}900nm$. A horizontal conductivity of the Hexadecyl Dipyridinium-$(TCNQ^-)_2$ LB film is about $10^{-7}(S/cm)$.