• Journal of the Korean Vacuum Society
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• v.5 no.4
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• pp.348-353
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• 1996

Rapid thermal annealing (RTA) was applied to polycrystalline CdTe thin films evaporated on CdS/ITO/glass substrate and the effect of the annealing temperatures and the atmosphere on physical properties of polycrystalline CdTe thin films and CdTe/CdS solar cell characteristics were studied. Results obtained by EDX showed that the bulk composition of CdTe remained stoichiometric after annealing at $550^{\circ}C$ in the air but the surface composition became Cd-rich. Cross-sectional TEM and micro EDX showed that columnar grains and micro-twins remained even after RTA, however, and the sulfur content in the annealed CdTe (added by sulfur diffusion from CdS during the annealing) was much smaller than that by furnace annealing. Among the investigated RTA temperatures and gas environments, the cell made with CdTe annealed at $550^{\circ}C$ in air showed the best solar energy conversion efficiency.

• Bulletin of the Korean Chemical Society
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• v.31 no.10
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• pp.2849-2853
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• 2010

A method to improve the photocatalytic activity of titanium dioxide by modification with a sensitizer and a metal oxide is proposed. To achieve this goal, we used metal oxides as dopants. In particular, $CaWO_4$ and $Gd_2O_2S$:Tb were used because their 2.6 eV and 2.2 eV band gap energy and optical properties have a large positive effect on photocatalysis. The improvement in the photocatalytic activity of $TiO_2$ modified with $Gd_2O_2S$:Tb under ultraviolet light irradiation is described in a previous study. The present work focuses on the sensitization of metal oxide-modified $TiO_2$. Having observed the ultraviolet-visible absorption spectra of 3,4,9,10-Perylenetetracarboxylic diimide in the wide visible-light region from 400 nm to 650 nm and the broad peaks in its photoluminescence spectra at 695 nm and 717 nm, we decided to use this perylene dye to sensitize modified $TiO_2$ to enhance its activity as a visible-light harvesting photocatalyst. We also explored the positive effects thin-film surface changes stemming from ultraviolet pre-treatment have on photocatalytic activity. Finally, we subjected several metal oxide-modified $TiO_2$ products sensitized by the perylene dye to ultraviolet pre-treatment, obtaining the most active photocatalysts.

• Korean Chemical Engineering Research
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• v.49 no.4
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• pp.405-410
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• 2011

A study on chemical vapor deposition(CVD) of $WO_3$ and the electrochromic properties of the CVD $WO_3$ films have been carried out. The crystalinity, purity, and growth rate of the films depending on substrate temperatures are investigated. The highest growth rate is $8{\mu}m/min$ at the substrate temperatures above $300^{\circ}C$ and the estimated activation energy for overall film growth is about 45.9 kJ/mol at the temperatures of $225{\sim}275^{\circ}C$, where the CVD process is controlled by a surface reaction kinetics. The films grown below $275^{\circ}C$ are amorphous, while those deposited above $300^{\circ}C$ are crystalline. The effects of thickness and deposition temperature of the $WO_3$ films on electrochromic activity are also investigated. The coloration efficiency of the films increases with increase in film thickness and decrease in deposition temperature.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.1
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• pp.43-50
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• 2012

The effects of parameters related to the finite element simulation of the laser shock peening(LSP) process on the residual stresses of Inconel alloy 600 steel are discussed. In particular, we focus on the maximum pressure, pressure pulse duration, laser spot size, and number of shots. It is found that certain ranges of the maximum pressure and pulse duration can produce the maximum compressive residual stresses near the surface, and thus proper choices of these parameters are important. The residual stresses are not affected by the laser spot size, provided it is larger than a certain size. The magnitudes of the compressive residual stresses and the plastically affected depths are found to increase with an increasing number of shots, but this effect is less pronounced for more shots.

• Membrane Journal
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• v.6 no.1
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• pp.44-52
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• 1996

For the purpose of the optimal design of a frame and plate type of pervaporation module, model equations which can predict the effects of feed flow condition on the temperature distribution of the feed developed in the module were established and the temperature distribution with feed flow condition was investigated through the model si$$\mu$ation. With increasing the Reynolds number of feed flow in the module, the flow velocity gradient in the channel height-direction as well as the volume rate of feed which acts as energy source for the evaporation of perrneants on the permeate-side surface of a membrane increased to such an extent that both mass and heat flux in the channel height direction could increase and the temperature drop of feed due to the evaporation of the permeant could be reduced correspondingly. A decrease in channel height caused the temperature drop of feed because of decreasing feed flow in the module. It was observed that the si$$\mu$ation result on the effect of Re on the temperature distribution of feed in the module has an agreement with experiment.

• Journal of the Microelectronics and Packaging Society
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• v.17 no.1
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• pp.19-24
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• 2010

The effects of $O_2$ plasma pretreatment on the properties of Ga-doped ZnO films on PET substrate were studied. GZO films were fabricated by RF magnetron sputtering process. To improve surface energy and adhesion between the PET substrate and the GZO film, $O_2$ plasma pretreatment process was used prior to GZO sputtering. As the RF power and the treatment time increased, the crystallinity increased and the contact angle decreased significantly. When the RF power was 100 W and the treatment time was 600 sec in $O_2$ plasma pretreatment process, the resistivity of GZO films on the PET substrate was $1.90{\times}10^{-3}{\Omega}-cm$.

• The Korean Journal of Pain
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• v.7 no.1
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• pp.74-77
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• 1994

Since its introduction, low level lasers have been utilized in many varied clinical applications for the treatment of musculoskeletal and body surface lesions. Due to the laser beams specific characteristic-coherence, monochromaticity and unidirectionality, without adverse reaction with neighbouring tissue, physicians have used it with relative ease. We observed accelerating effects of healing process of some intractable skin wound, improvement of graft survival, as well as reduction of pain on ulcerating tissues, by treating twice weekly with low level Helium-Neon(He-Ne) and Infrared(IR) laser. The laser's energy density was set at $1\;J/cm^2$ and a fixed frequency of 600 Hz by continuous scanning. Irradiating time was calculated according to the cross diameter of the wound. Further clinical work will be required to evaluate the accelerated healing processes by biostimulating mechanisms of laser ray, especially for the intractable(diabetic) skin ulceration.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.111-111
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• 2007

Further scaling the semiconductor devices down to low dozens of nanometer needs the extremely shallow depth in junction and the intentional counter-doping in the silicon gate. Conventional ion beam ion implantation has some disadvantages and limitations for the future applications. In order to solve them, therefore, plasma source ion implantation technique has been considered as a promising new method for the high throughputs at low energy and the fabrication of the ultra-shallow junctions. In this paper, we study about the effects of DC bias and base pressure as a process parameter. The diluted mixture gas (5% $PH_3/H_2$) was used as a precursor source and chamber is used for vacuum pressure conditions. After ion doping into the Si wafer(100), the samples were annealed via rapid thermal annealing, of which annealed temperature ranges above the $950^{\circ}C$. The junction depth, calculated at dose level of $1{\times}10^{18}/cm^3$, was measured by secondary ion mass spectroscopy(SIMS) and sheet resistance by contact and non-contact mode. Surface morphology of samples was analyzed by scanning electron microscopy. As a result, we could accomplish the process conditions better than in advance.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.26 no.7
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• pp.503-509
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• 2013

In this study, $Cu(In_{1-x},Ga_x)Se_2$ (CIGS) thin films were prepared on the Mo coated soda-lime glass by the DC magnetron sputtering and a subsequent selenization process. For the selenization process, selenization rapid thermal process(RTP) with cracker cell, which was helpful to smaller an atomic of Se, was adopted. To make CIGS layer, they were then annealed with the cracked Se. Based on this selenization method, we made several CIGS thin film and investigated the effects of In deposition time, and selenization time. Through x-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive spectroscopy (EDS), and atomic force microscopy (AFM), it is found that the Mo/In/CuGa structure and the high sputtering power shows the dominant chalcopyrite structure and have a uniform distribution of the grain size. The CIGS films with the In deposition time of 5 min has the best structure due to the smooth surface. And CIGS films with the selenization time of 50 min show good crystalline growth without any voids.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.281.2-281.2
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• 2013

Since heavy metal ions included in water or food resources have critical effects on human health, highly sensitive, rapid and selective analysis for heavy metal detection has been extensively explored by means of electrochemical, optical and colorimetric methods. For example, quantum dots (QDs), such as semiconductor QDs, have received enormous attention due to extraordinary optical properties including high fluorescence intensity and its narrow emission peaks, and have been utilized for heavy metal ion detection. However, the semiconductor QDs have a drawback of serious toxicity derived from cadmium, lead and other lethal elements, thereby limiting its application in the environmental screening system. On the other hand, Graphene oxide (GO) has proven its superlative properties of biocompatibility, unique photoluminescence (PL), good quenching efficiency and facile surface modification. Recently, the size of GO was controlled to a few nanometers, enhancing its optical properties to be applied for biological or chemical sensors. Interestingly, the presence of various oxygenous functional groups of GO contributes to opening the band gap of graphene, resulting in a unique PL emission pattern, and the control of the sp2 domain in the sp3 matrix of GO can tune the PL intensity as well as the PL emission wavelength. Herein, we reported a photoluminescent GO array on which heavy metal ion-specific DNA aptamers were immobilized, and sensitive and multiplex heavy metal ion detection was performed utilizing fluorescence resonance energy transfer (FRET) between the photoluminescent monolayered GO and the captured metal ion.