• Journal of the Korean Society of Costume
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• v.50 no.4
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• pp.89-102
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• 2000

The purpose of this study was to research Korean Jowoo-Guan and Chinese Hal-Guan and study transition and symbolism of the birds feather in the cap. The culture of ancient Korea was influenced by North Asia prior to the influence of the Chinese culture, One of the remarkable thing, as the cultural factor of North Asia is the birds worship thought. Korean Jowoo-Guan was derived from the birds worship thought. So in dealing with the plume of Korean Jowoo-Guan, we must recognize Worship to the bird and the symbolical meaning of the bird. The results of study was as follow. 1. Korean Jowoo-Guan was influenced worship to the sun, so it's wearing symbolized the governing class. As the Social development and governing class, the feathering cap was developed to a gold crown, and also the gold crown of Samguk times had been influenced style of North Asia culture. But afterwards the symbolical meaning of the bird was waning, only decorative meaning was remained. 2. Chinese Hal-Guan was warn in Joo-dynasty, but the symbolism of the plume in the cap was not similar to Korean Jowoo-Guan. Chinese Hal-Guan was symbolized bravery of superfluous soldier than Worship to the bird. But afterwards the symbolical meaning of bravery of superfluous soldier was waning, only decorative moaning was remained. 3. Though neighbor countries have mutually influenced and have similar cultural style, they have symbolism of themselves

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.11a
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• pp.134-134
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• 2009

We studied electrochemical properties of $TiO_2$ photoelectrode based graphene for dye-sensitized solar cells(DSSC). Gaphene has good electric conductivity and it is very good transparent when this is coated on monolayer. we prepared photoelectrode by squeeze methode and researched photoelectrical properties of $TiO_2$ electrode base gaphene. DSSC based on graphene was obtained conversion efficiency of 5.4% under irradiation of AM 1.5(100 $mWcm^2$).

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.11a
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• pp.132-132
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• 2009

Phospho-olivine $LiFePO_4$ cathode materials were prepared by hydrothermal reaction. In this study, Multi-walled carbon nanotube (MWCNT) and Carbon black was added to enhance the electrical conductivity of $LiFePO_4$. $LiFePO_4$, $LiFePO_4$-MWCNT and $LiFePO_4$-C particles were characterized by X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM) transmission electron microscope (TEM). $LiFePO_4/SPE/Li$, $LiFePO_4$-MWCMT/SPE/Li and $LiFePO_4$-C/SPE/Li cells were characterized electrochemically by charge/discharge experiments at a constant current density of $0.1mA\;cm^{-2}$ in a range between 2.5 and 4.3 V vs. $Li/Li^+$ and cyclic voltammetry (CV).

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.11a
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• pp.133-133
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• 2009

Phospho-olivine $LiFePO_4$ and $LiTi_{0.1}Fe_{0.9}PO_4$ cathode materials were prepared by the solid-state reaction. To improve conductivity we carried out electrochemical performance of $Ti^{2+}$ doped $LiFePO_4$. The $Ti^{2+}$ doped $LiFePO_4$ started 3.36 V of flat voltage on discharge curve and showed a gentle decline in the curve compared to undoped $LiFePO_4$ without great changes of capacity. And so, we could achieve to improve electrochemical performance as reversible, cycle life. Similarly, $LiFePO_4$ doping with $Ti^{2+}$ was showed the effect of dopant which was obtained the improved discharge capacity as 140 mAh/g and good cycling performance.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.24 no.5
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• pp.427-431
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• 2011

Hybrid $SiO_2-TiO_2$ photoelectrode with different type of layers was investigated in dye-sensitized solar cells (DSSC). Use of a thin layer of nanocrystalline $TiO_2$ would imply reduction in the amount of dye coverage, however, lower amount of dye in the thin films would imply fewer electron generation upon illumination. So, thus, it becomes necessary to include a $SiO_2-TiO_2$ layer for increase light harvesting effect such that the lower photon conversion due to thin layer could be compensated. In this paper reports the use of transparent high surface area $TiO_2$ layer and an additional $SiO_2-TiO_2$ layer, thus ensuring adequate light harvesting in these devices. The best solar conversion efficiency 6.6% under AM 1.5 was attained with a multi-layer structure using $TiO_2$ layer/$SiO_2-TiO_2$ layer/$TiO_2$ layer for the light harvesting and this had resulted to about 44% increase in photocurrent density of dye-sensitized solar cells.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.25 no.2
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• pp.153-158
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• 2012

We use UV(ultraviolet)-$O_3$ treatment to increase the surface area and porosity of $TiO_2$ films in dye-sensitized solar cells (DSSCs). After the UV-$O_3$ treatment, surface area and porosity of the $TiO_2$ films were increased, the increased porosity lead to amount of dye loading and solar conversion efficiency was improved. Field emission scanning electron microscopy images clearly showed that the nanocrystalline porosity of films were increased by UV-$O_3$ treatment. The Brunauer, Emmett, and Teller surface area of the $TiO_2$ films were increased from $0.71cm^2/g$ to $1.31cm^2/g$ by using UV-$O_3$ treatment for 20 min. Also, UV-$O_3$ treatment of $TiO_2$ films significantly enhanced their solar conversion efficiency. The efficiency of the films without treatment was 4.9%, and was increased to 5.6% by UV-$O_3$ treatment for 20 min. Therefore the process enhanced the solar conversion efficiency of DSSCs, and can be used to develop high sensitivity DSSCs.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.27 no.1
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• pp.33-38
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• 2014

In this work, according to temperature and time of hydrothermal synthesis, the electrochemical properties of $TiO_2$ particle using TTIP based on changing temperature and time in the hydrothermal synthesis were analyzed and optimized temperature and time were derived. When hydrothermal synthesis temperature and time were $200^{\circ}C$ and 1 h, respectively. The fabricated DSSC delivered the best electrochemical properties. In that case, $TiO_2$ particle size was 13.08 nm, electron transport time was $2.34{\times}10^{-3}s$ and recombination time was $4.01{\times}10^{-2}s$. The lowest impedance of $13.52{\Omega}$ and Voc, Jsc, FF is 0.70 V, $1.50mAcm^{-2}$, 65.62%, respectively and corresponding efficiency of 5.34% was considered as the optimal.

• 한국신재생에너지학회:학술대회논문집
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• 2011.11a
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• pp.55.1-55.1
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• 2011

Dye-sensitized solar cell(DSSC) have been considered one of the promising alternatives to conventional solar cells, because of their low cost, easy fabrication and relatively high energy conversion efficiency. However, although the cell offers reasonable efficiency at least 11%, the use of a liquid electrolyte placed technological challenges for achieving the desired durability and operational stability of the cell. In order to prevent or reduce electrolyte leakage considerable efforts have been made, such as p-type semiconductor or organic hole-transport material that better mechanical properties and simple fabrication processes. In this work, we synthesized solid-state electrolyte containing LiI and KI metal salt with starting materials of poly ethylene oxide to substitute liquid electrolyte enhance the ionic conductivity and solar conversion efficiency. Li+ leads to faster diffusion and higher efficiency and K+ leading to higher ionic conductivity. The efficiency of poly ethylene oxide/LiI system electrolyte is 1.47% and poly ethylene oxide/potassium electrolyte is 1.21%. An efficiency of 3.24% is achieved using solid-state electrolyte containing LiI and KI concentrations. The increased solar conversion efficiency is attributed to decreased crystallinity in the polymer that leads to enhanced charge transfer.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.27 no.11
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• pp.718-724
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• 2014

In this work, in order to manufacture the photoelectrode of dye-sensitized solar cells, the different anatase $TiO_2$ paste was prepared by simple route using hydrothermal method. In comparison with the traditional preparing process, the hydrothermally synthesized $TiO_2$ gel was used to make paste directly. Thus, the making process was simplified and the solar conversion efficiency was improved. In comparison with 5.34% solar energy efficiency of HP-1 photoelectrode, the 6.23% efficiency of HDP-1 electrode was improved by 16.67%. This is because hydrothermally synthesized $TiO_2$ gel was used to make paste directly, the dispersibility between $TiO_2$ particles was improved and get the smoother network, leading to the charge transport ability of the electron generated in dye molecular was improved. Further, HDP-2 photoelectrode delivered the best results with Voc (open circuit voltage), Jsc (short circuit current density) FF (fill factor) and ${\eta}$(solar conversion efficiency) were 0.695 V, $15.81mA\;cm^{-2}$, 61.48% and 6.80%, respectively. In comparison with 5.34% of HP-1 photoelectrode, it was improved by 27.34%.