• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.126-126
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• 2014

Label-free biomolecular assay based localized surface plasmon resonance (LSPR) of noble metal nanoparticles enables simple and rapid detection with the use of simple equipment. Nanosized metal nanoparticles exhibit a strong absorption band when the incident light frequency is resonant with the collective oscillation of the electrons, which is known as the LSPR. Here we demonstrate localized surface plasmon resonance (LSPR) substrates such as plasmonic Au nanodisks fabricated by a nanoimprinting process and gold nanorod-immobilized surfaces and their applications to highly sensitive and/or label-free biosensing. To increase detection sensitivity various bioreceptors weree designed. A single chain variable fragment (scFv) was used as a receptor to bind C-reactive protein (CRP). The results of this effort showed that CRP in human serum could be quantitatively detected lower than 1 ng/ml. Aptamers, which were immobilized on gold nanorods, were used to detect mycotoxins. The specific binding of ochratoxin A (OTA) to the aptamer was monitored by the longitudinal wavelength shift of LSPR peak in the UV-Vis spectra resulting from the changes of local refractive index near the GNR surface induced by accumulation of OTA and G-quadruplex structure formation of the aptamer. According to our results, OTA could be quantitatively detected lower than 1 nM level. Additionally, aptamer-functionalized GNR substrate was quite robust and can be regenerated many times by rinsing at 70 OC to remove bound target. During seven times of washing steps, the developed OTA sensing system could be reusable. Moreover, the proposed biosensor exhibited selectivity over other mycotoxins with an excellent recovery for detection in grinded corn samples, suggesting that the proposed LSPR based aptasensor plays an important role in label-free detection of mycotoxins.

• Proceedings of the Materials Research Society of Korea Conference
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• 2010.05a
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• pp.35.1-35.1
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• 2010

The Cu(In,Ga)Se2(CIGS) thin film solar cells have been achieved until almost 20% efficiency by NREL. These solar cells include chemically deposited CdS as buffer layer between CIGS absorber layer and ZnO window layer. Although CIGS solar cells with CdS buffer layer show excellent performance, many groups made hard efforts to overcome its disadvantages in terms of high absorption of short wavelength, Cd hazardous element. Among Cd-free candidate materials, the CIGS thin film solar cells with Zn compound buffer layer seem to be promising with 15.2%(module by showa shell K.K.), 18.6%(small area by NREL). However, few groups were successful to report high-efficiency CIGS solar cells with Zn compound buffer layer, compared to be known how to fabricate these solar cells. Each group's chemical bah deposition (CBD) condition is seriously different. It may mean that it is not fully understood to grow high quality Zn compound thin film on the CIGS using CBD. In this study, we focused to clarify growth mechanism of chemically deposited Zn compound thin film on the CIGS, especially. Additionally, we tried to characterize junction properties with unfavorable issues, that is, slow growth rate, imperfect film coverage and minimize these issues. Early works reported that film deposition rate increased with reagent concentration and film covered whole rough CIGS surface. But they did not mention well how film growth of zinc compound evolves homogeneously or heterogeneously and what kinds of defects exist within film that can cause low solar performance. We observed sufficient correlation between growth quality and concentration of NH3 as complex agent. When NH3 concentration increased, thickness of zinc compound increased with dominant heterogeneous growth for high quality film. But the large amounts of NH3 in the solution made many particles of zinc hydroxide due to hydroxide ions. The zinc hydroxides bonded weakly to the CIGS surface have been removed at rinsing after CBD.

• Korean Journal of Materials Research
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• v.8 no.3
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• pp.219-223
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• 1998

Spectroscopic properties of $Eu^{3+}$, $Sm^{3+}$, $Tb^{3+}$ ions in silicate glasses have been studied. The absorption and emission properties were investigated with the wavelength and rare-earth element concentration. The results showed that the emission spectrum of $Sm^{3+}$ was a transition from $^{5}D_{o}$ excited level to ^{7}F$ ground state and $Sm^{3+}$ was from $4F_{5/2}$ to $^{6}H$ and $Tb^{3+}$ was from $^{5}D_{4}$ to ^{7}F$ The emission intensity was linearly increased with rare-earth element concentrations up to 10wt%.

• Korean Chemical Engineering Research
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• v.47 no.1
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• pp.105-110
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• 2009

IZO thin films have been deposited on poly(ethylene terephthalate) flexible substrate under varying radio frequency (rf) power, process pressure and thickness of IZO films using rf magnetron sputtering under $Ar/O_2$ gas mix. As the process pressure increased, the deposition rate was slightly increased and the transmittance showed little change, but the resistivity was increased. With increasing rf power, the great increase in deposition rate was observed but the transmittance showed a slight change only, and the resistivity was decreased. In addition, an attempt was made to find the optimal thickness of IZO films under varying the thickness of IZO films at the process conditions of 1 mTorr pressure and 90 W rf power, which showed lowest resistivity. IZO thin films with the thickness of $1,500{\AA}$ showed lowest resistivity and also showed highest transmittance around the wavelength zone of the maximum absorption. The power conversion efficiency of solar cells fabricated using various transparent electrodes with different thicknesses were measured and the solar cell with IZO electrode of $1,500{\AA}$ showed the maximum conversion-efficiency of 2.88 %.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.280-280
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• 2010

Semiconductor quantum dots are of great interest for both fundamental research and industrial applications due to their unique size dependant properties. The most promising application of colloidal semiconductor nanocrystals (quantum dots or QDs) is probably as emitters in biomedical labeling, LEDs, lasers etc. As compared to II-VI quantum dots, III-V have attracted greater interest owing to their less ionic lattice, larger exciton diameters and reduced toxicity. Among the III-V semiconductor quantum dots, Indium Phosphide (InP) is a popular material due to its bulk band gap of 1.35 (eV) which is responsible for the photoluminescence emission wavelength ranging from blue to near infrared with change in size of QDs. Nevertheless, in recent years, the exact type of collective properties that arise when semiconductor quantum dots (QDs) are assembled into two- or three-dimensional arrays has drawn much interest. The term "uantum dot solids" is used to indicate three-dimensional assemblies of semiconductor QDs. The optoelectronic properties of the quantum dot solids are known to depend on the electronic structure of the individual quantum dot building blocks and on their electronic interactions. This paper reports an efficient and rapid method to produce highly luminescent and monodisperse quantum dots solution and solid through fabrication of InP thin films. By varying the molar concentration of Indium to Ligand, QDs of different size were prepared. The absorption and emission behaviors were also studied. Similar measurements were also performed on InP quantum dot solid by fabricating InP thin films. The optical properties of the thin films are measured at different curing temperatures which show a blue shift with increase in temperature. The dielectric properties of the thin films were also investigated by Capacitance-voltage(C-V) measurements in a metal-insulator-semiconductor (MIS) device.

• Korean Journal of Optics and Photonics
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• v.11 no.3
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• pp.147-151
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• 2000

We deposited the ion assisted ${Ta_2}{O_5}$ films and conventional thermal evaporated ${Ta_2}{O_5}$ films by using electron beam gun, and measured the optical properties and mechanical properties of the fabricated films according to the evaporation conditions. In the case of the TazOs films by oxygen ion assisted deposition with the anode voltage of 120 V, and current density of $50~500\muA/cm^2$, the refractive index exhibited 2.15 which was higher than the conventionally deposited film index 1.94 and the tensile stress exhibited $5.0\times10^8 dyne/cm^2$ which was lower than $7.0\times10^8 dyne/cm^2$. This properties coincided with the optical and mechanical properties of the films deposited at the elevated substrate temperature of $230^{\circ}C$. In the case of the argon ion assisted films the tensile stress was decreased but the absorption existed at the short wavelength in the visible spectral region. And all the fabricated films were found to be amorphous by the X-ray diffraction analysis. lysis.

• Journal of Fashion Business
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• v.11 no.2
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• pp.92-101
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• 2007

This research was carried out following the preceding research on natural cellulose fabrics dyed with extract of fresh african marigold petals. Dyeability on fabrics was tested by dyeing with wool and silk which are natural protein fibers. Dyeing tests were carried out under different pH of the dye solution and mordants, examining the changes in the surface color, K/S value, and maximum absorption wavelength. The probability of improving dyeability was investigated by pre-mordanting with pre-treated chitosan. Wool fabrics showed color tone of medium or less saturation and brightness, in dark yellow color series. An orange color of high saturation was only obtained by tin mordanting. Wool showed higher K/S value than cellulose fibers. In summary, marigold dye has more affinity for protein fibers. It showed better dye effect in wool than silk. The chitosan pre-treatment and pre-mordanting lowered the K/S value of wool, which showed that chitosan pre-treatment does not improve dye uptake. However, different from the dyeing carried out by pre-mordanting without pre-treatment with chitosan, more diversified colors could be obtained by mordants. Therefore, for the dyeing natural protein fibers with marigold extract, post-mordanting does not require chitosan pre-treatment. However, pre-mordanting with chitosan pre-treatment could implement diverse colors. Considering its dyeing behaviors which are similar in both natural cellulose and protein fibers, african marigold extracts can be evaluated as a stable and highly practical dye.

• KSBB Journal
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• v.9 no.5
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• pp.469-474
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• 1994

The purpose of the work was to evaluate the feasibility of a biological treatment process for the phenoxy alkanoic herbicide 2,4-D(2,4-dichlorophenoxyacetic acid) as a commercial pesticide. The phenoxy herbicide was 2,4-D amine salts which contained 40%(vol/vol) 2,4-D and 60%(vol/vol) solvent. A microbial consortium has been derived by enrichment with 2,4-D. The consortium utilized 2,4-D as the sole source of carbon and energy. Optimal pH on the 2,4-D degradation was 7.0 in this experiment. As concentrations of 2,4-D were increased, the degradation by microbial consontium became inhibited. The amendment with yeast extract and ascorbic acid accelerated the degradation of 2,4-D. High performance liquid chromatography methodology was used to measure 2,4-D and it also resolved 2,4-DCP(2,4-dichlorophenol), the corresponding phenol as intermediate. Gas chromatography-mass spectrometry was used for preliminary identification of the intermediate 2,4-DCP. UV scans of spent cultures showed that the maximum absorption of 2,4-D at the wavelength of 283 nm was decreased toward the end of incubation, but the consortium displayed no detectable spectral changes or peak shifts in the UV absorbance.

• Korean Journal of Materials Research
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• v.23 no.3
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• pp.194-198
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• 2013

In this paper, we studied a p-type reflector based on indium tin oxide (ITO) for vertical-type ultraviolet light-emitting diodes (UV LEDs). We investigated the reflectance properties with different deposition methods. An ITO layer with a thickness of 50 nm was deposited by two different methods, sputtering and e-beam evaporation. From the measurement of the optical reflection, we obtained 70% reflectance at a wavelength of 382 nm by means of sputtering, while only 30% reflectance resulted when using the e-beam evaporation method. Also, the light output power of a $1mm{\times}1mm$ vertical chip created with the sputtering method recorded a twofold increase over a chip created with e-beam evaporation method. From the measurement of the root mean square (RMS), we obtained a RMS value 1.3 nm for the ITO layer using the sputtering method, while this value was 5.6 nm for the ITO layer when using the e-beam evaporation method. These decreases in the reflectance and light output power when using the e-beam evaporation method are thought to stem from the rough surface morphology of the ITO layer, which leads to diffused reflection and the absorption of light. However, the turn-on voltage and operation voltage of the two samples showed identical results of 2.42 V and 3.5 V, respectively. Given these results, we conclude that the two ITO layers created by different deposition methods showed no differences in the electric properties of the ohmic contact and series resistance.

• Polymer(Korea)
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• v.30 no.5
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• pp.417-421
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• 2006

Photo -alignment of poly (siloxane cinnamate) (PSCN) was studied to better understand the alignment mechanism of cynnamoyl groups under various process conditions. DSC and polarized microscope studies showed that the isotropic temperature oi PSCN was about $105^{\circ}C$ and the liquid crystallinity, once formed, did not completely disappear even when the temperature went into the isotropic regions. UV/Vis absorption study suggested that the photo - dimerization was the main photo alignment mechanism and it's efficiency could be enhanced through the self-alignment of PSCN. It was also found that photo-dimerization was in competition with photo-fries reaction and the photo- alignment of PSCN was interfered with the excessive UV because of the strong photo-fries reaction. However, photo - fries reaction could be suppressed by adjusting the UV wavelength.