• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.24 no.1
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• pp.76-80
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• 2011

The ITO/Cabon Nano Tube (CNT) nano composites were deposited by nano cluster deposition (ITO) and arc discharge deposition (CNT) on glass substrates. The structural, optical and photovoltaic performance of ITO/CNT nano composites as a counter electrode of dye-sensitized solar-cells (DSSCs) such films were investigated. At low temperature below $250^{\circ}C$, the ITO films deposited on CNT. The ITO/CNT nano composit showed a good optical and electrical property for the counter electrode of DSSCs. When the as-prepared ITO/CNT nano composites are used for the counter electrodes, the photovoltaic parameters are $V_{OC}$ = 0.69 V, $J_{SC}$ = 5.69 mA/$cm^2$, FF = 0.32, and $\eta$ = 0.53 %. The ITO/CNT nano composites showed the possibility for the counter electrode applications of DSSCs.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.25 no.7
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• pp.558-562
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• 2012

As an alternative energy, Dye-sensitized solar cells (DSSCs) have received much attention due to low cost manufacturing procedure and high energy consumption rate. Incorporating scattering centers in the nanocrystalline photoanode or additional scattering layers on the nanocrystalline photoanode is an effective way to enhance the light harvest efficiency of the photoanode and the performance of dye-sensitized solar cells (DSSCs). The light scattering abilities of these scattering layers also depend on the relative sizes and phase of the particles in the layers. A higher surface area is normally obtained using large particle sizes. Therefore, transparent high surface area $TiO_2$ layers and an additional scattering layer consisting of $TiO_2$-Rutile 500 nm paste with relatively larger particles are attractive. In this work, we investigates the applicability of a hybrid $TiO_2$ electrode (or a working electrode with a light scattering layer) in a DSSCs. We fabrication various thin film using $TiO_2$ paste 20 nm and $TiO_2$ paste 500 nm. As a result, the efficiency of the a single structure thin film was 3.35% and the efficiency as scattering layer of hybrid structure thin film was 4.36%, 4.73%.

• Journal of the Korean Society of Visualization
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• v.15 no.1
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• pp.41-46
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• 2017

Control of mixing and transport processes are the key areas that can be benefited by understanding the hydrodynamics in gas-liquid two-phase flows. In particular, the enhanced bubble-induced liquid-phase mixing is known to be a function of void fraction distribution, gas phase velocity and so on. To further our insight on the characteristics of the liquid-phase mixing induced by the bubbles, in the present study, we experimentally investigate the mixing performance of a rectangular bubble column while changing the void fraction from 0.006 to 0.075%. A shadowgraphy technique is used to measure the gas-phase properties such as void fraction and size/velocity of bubbles. On the other hand, we use dye visualization with low diffusive buoyant dye to directly measure the level of mixing. Finally, we confirm that the time taken for full mixing scales with the inverse of volume void fraction.

• Journal of Sensor Science and Technology
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• v.26 no.6
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• pp.420-426
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• 2017

A colorimetric sensor was investigated to achieve a low-cost warning device for harmful gaseous formaldehyde (HCHO). The sensor is based on selective reactions between hydroxylamine sulfate and HCHO, leading to the production of sulfuric acid. The produced acid results in color-changing response through the acid-base reaction with dye molecules impregnated on a solid membrane substrate. For attaining this purpose, sensors were fabricated by drop-casting a dye solution prepared using different pH indicators on various commercially available polymer sheets, and their colorimetric responses were evaluated in terms of sensitivity and reliability. The colorimetric sensor using bromophenol blue (BPB) and nylon sheet was found to exhibit the best performance in HCHO detection. An initial bluish green of a sensor was changed to yellow when exposed to gaseous formaldehyde. The color change was recorded using an office scanner and further analyzed in term of RGB distance for quantifying sensor's response at different HCHO(g) concentrations. It exhibited a recognizable colorimetric response even at 50 ppb, being lower than WHO's standard of 80 ppb. In addition, the sensor was found to have quite good selectivity in HCHO detection under the presence of common volatile organic compounds such as ethanol, toluene, and hexane.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.1256-1257
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• 2008

Dye-Sensitized Solar Cell(DSSC) is a new type of solar cell by using photocatalytic properties of $TiO_2$. The size and shape of $TiO_2$ particle are two of important parameters that are related to the characteristics of DSSC. And these can be changed by controlling $TiO_2$ sintering conditions especially temperature. The particles of $TiO_2$ are classified anatase and rutile. Anatase particles are created at low sintering temperature and rutile particles are created at high sintering temperature. Anatase particles have advantages such as increased surfaces that cause more attached dye molecules, and fast electron transportation. And rutile particles have advatages such as more efficient light scattering. Therefore, we studied characteristics of DSSC in this paper as $TiO_2$ sintering temperature is varied. As a result, we found that characteristics of DSSC are very good in the case that anatase and rutile particles are together and this sintering temperature is 450$^{\circ}C$.

• Journal of the Korean Home Economics Association
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• v.35 no.3
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• pp.115-124
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• 1997

In this study, Water Repellent Finish was carried out before dyeing on cotton fabrics. It was aimed to improve on dyeing properties of cotton fabrics with direct dye. The results obtained were summerized as follows: 1. The K/S value of water repellent finished cotton fabrics increased. This phenomena in water repellent finished cotton fabrics were much more noticiable than unfinished cotton fabrics. 2. The color fastness(light, washing, and rubbing) of water repellent finished cotton-dyed were worse than those of unfinished cotton-dyed with direct dye. △E of water repellent finished cotton fabrics wasn't showed significant difference as compared with that of unfinished cotton fabrics. 3. The water repellency of finished cotton after dyeing got down from 100 to 70. That of finished-cotton before dyeing was 100. 4. Moisture regain, stiffness and weight of finished cotton fabrics were not almost differenciated with unfinished cotton fabrics. Moreover, the tensile strength of finished cotton fabrics was increased compared to that of unfinished cotton fabrics. As conclusion, according to the above results when the cotton fabrics were dyed with direct dye, it was much more effective that water repellent finished cotton fabrics were dyed rather than trational process, that is pre-dyeing after-finishing even if, by low liquor ratio. The physical properties of fabrics were maintained or increased.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.445.1-445.1
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• 2014

Dye-sensitized solar cells (DSSCs) have been widely investigated as a next-generation solar cell because of their simple structure and low manufacturing cost. The $TiO_2$ film with thickness of $8{\sim}10{\mu}m$, which consists of nanoparticles, acts as both a scaffold with a high surface-to-volume ratio for the dye loading and a pathway to remove the electrons. However, charge carriers have to move across many particle boundaries by a hopping mechanism. So, one dimensional nanostructures such as nanotubes, nanorods and nanowires should improve charge carrier transportation by providing a facile direct electron pathway and lowering the diffusion resistance. However, the efficiencies of DSSCs using one dimensional nanostructures are less than the $TiO_2$ nanoparticle-based DSSCs. In this work, the patterned $TiO_2$ film with thickness of $3{\mu}m$ was deposited using photolithography process to decrease of electron pathway and increase of surface area and transmittance of $TiO_2$ films. Properties of the patterned $TiO_2$ films were investigated by various analysis method such as X-ray diffraction, field emission scanning electron microscopy (FESEM) and UV-visible spectrophotometer.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.453.1-453.1
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• 2014

Fluorine-doped tin oxide (FTO), which is commonly used in dye-sensitized solar cells (DSSCs), is a promising material of transparent conducting oxides (TCOs) because of advantages such as high chemical stability, high resistance, high optical transparency (>80% at 550nm), and low electrical resistivity (${\sim}10-4{\Omega}{\cdot}cm$). Especially, dye-sensitized solar cells (DSSCs) have been actively studied since Gratzel's research group required FTO substrate as a charge collector. When FTO substrates are used in DSSCs, photo-injected electrons may experience recombination at interface between dye-bonded semiconductor oxides ($TiO_2$) on FTO substrate and the electrolyte. To solve these problems, one is that because recombination at FTO substrate cannot be neglected, thin $TiO_2$ layer on FTO substrate as a blocking layer was introduced. The other is to control the morphology of surface on FTO substrate to reduce a loss of electrons. The structural, electrical, and optical characteristics of morphology controlled-FTO thin films as TCO materials were analyzed by X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM), Hall Effect Measurement, and UV spectrophotometer. The performance of DSSCs fabricated with morphology controlled FTO substrates was performed using Power Conversion Efficiency (PCE). We will discuss these results in detail in Conference.

• Journal of the Korean Society of Clothing and Textiles
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• v.35 no.7
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• pp.736-747
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• 2011

This study investigates the current status and dyeing properties of various natural indigo powder dyes in the domestic market. Products from India, China, Europe are sold in the market and only a few manufacturers provide recommendation for the method of dyeing and information on the additives. Through the market research and the preliminary investigation on 21 products, 11 were selected for the dyeing experiment which include 3 Indian, 3 Chinese, 2 German, and 1 Pakistani origin indigo reduced powders, and 2 Indian origin dried indigo leaf powder. The two dyeing methods used were the precipitation method and the fresh juice method, both at $10^{\circ}C$, $25^{\circ}C$, and $60^{\circ}C$. Color difference, K/S value, and colorfastness of dyed cotton fabrics were examined. Indian reduced indigo powder showed the highest K/S value, deep dyeing, and the best color fastness. Chinese reduced indigo powder resulted in a more greenish and bluish color. Powders of dried indigo leaves were easy to use but resulted in a pale color due to low dye uptake.

• Textile Coloration and Finishing
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• v.27 no.4
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• pp.301-308
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• 2015

This study optimizes dyeing conditions for polyamide-imide fabric using cationic dyes. Dyeing and fastness characteristics of polyamide-imide fabric were investigated with three cationic dyes and 2-hydroxyacetophenone as a swelling agent under various dyeing conditions such as dye and swelling agent concentrations, dyeing temperature and time, pH of dye bath. The dyeing properties were evaluated in terms of dye exhaustion, K/S value and color fastness. The optimized dyeing temperature and time were $130^{\circ}C$ for 90 min for the dyes. Under weak acidic conditions in the range pH 5 to 7, the exhaustion of cationic dyes could be enhanced leading to higher adsorption. Wash and rubbing fastness properties were generally good, while light fastness was slightly low, which can be attributed to the poor photo-stability of the cationic dyes.