• 보존과학연구
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• s.29
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• pp.221-238
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• 2008

Roofing tiles are very important archaeological artifacts which show science, architecture of that time, as well as information about the culture. It has been studied by many researchers steadily, but only focusing on archaeological, art historical and architectural study, so it is very difficult to find natural science research. Gyeongbokgung's roofing tiles were excavated from the ruins of same site, however glaze, body colour and shape of tiles are very diverse with the naked eye. Through natural science research which analyze the chemical composition and physical characteristics of roofing tiles's body and glaze examine the physical and chemical characteristics of each roofing tiles. the result of analazed roofing tiles is following. when roofing tiles were classified by 전암대자율 and chromaticity, each group has part of some matches. When you compare with green gazed traditional brick's glaze of Silla period, Gyeongbokgung roofing tiles have more $Al_2O_3$ and less PbO than Silla period's. We can see the technology of increasing firing temperature is better. and glaze colour depends on content of $Fe_2O_3$ and CuO. A lot of CuO tend to be more blue.

• Korean Journal of Materials Research
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• v.21 no.9
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• pp.482-485
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• 2011

$La_{0.6}Sr_{0.4}MnO_3$ (LSMO) thin films, which are known as colossal magnetoresistance materials, were prepared on fused silica thin films by conventional RF magnetron sputtering, and the interfacial reactions between them were investigated by rapid thermal processing. Various analyses, namely, X-ray diffraction, transmission electron microscopy combined with energy adispersive X-ray spectrometry, and secondary ion mass spectrometry, were performed to explain the mechanism of the interfacial reactions. In the case of an LSMO film annealed at $800^{\circ}C$, the layer distinction against the underplayed $SiO_2$ was well preserved. However, when the annealing temperature was raised to $900^{\circ}C$, interdiffusion and interreaction occurred. Most of the $SiO_2$ and part of the LSMO became amorphous silicate that incorporated La, Sr, and Mn and contained a lot of bubbles. When the annealing temperature was raised to $950^{\circ}C$, the whole stack became an amorphous silicate layer with expanded bubbles. The thermal instability of LSMO on fused silica should be an important consideration when LSMO is integrated into Si-based solid-state devices.

• Transactions of the Korean hydrogen and new energy society
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• v.23 no.6
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• pp.654-659
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• 2012

The interest in water gas shift (WGS) reaction has grown significantly, as a result of the recent advances in fuel cell technology and the need to develop small-scale fuel processors. Recently, researchers have tried to overcome the disadvantages of the commercial WGS catalysts. As a consequence, supported Pt catalysts have attracted a lot of researchers due to high activity and stability for WGS at low temperatures. In this study, $Pt-Na/Ce_{(1-x)}Zr_{(x)}O_2$ catalysts with various Ce/Zr ratio have been applied to WGS at a gas hourly space velocity (GHSV) of $45,515h^{-1}$. According to TPR patterns of $Pt-Na/Ce_{(1-x)}Zr_{(x)}O_2$ catalysts, the reducibility increases with decreasing the $ZrO_2$ content. As a result, Cubic structure $Pt-Na/Ce_{(1-x)}Zr_{(x)}O_2$ catalysts exhibited higher CO conversion than tetragonal structure $Pt-Na/Ce_{(1-x)}Zr_{(x)}O_2$ catalysts. Expecially, Pt-Na/$CeO_2$ exhibited the highest CO conversion as well as 100% selectivity to $CO_2$. Moreover, Pt-Na/$CeO_2$ catalyst showed relatively stable activity with time on stream. The high activity of cubic structure Pt-Na/$CeO_2$ catalyst was correlated to its higher oxygen storage capacity (OSC) of $CeO_2$ and easier reducibility of Pt/$CeO_2$.

• Journal of Environmental Health Sciences
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• v.29 no.1
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• pp.51-61
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• 2003

Pollution purification using titanium dioxide (TiO$_2$) photocatalyst has attracted a great deal of attention with increasing number of relent environmental problems. Currently, the application of TiO$_2$ photocatalyst has been focused on purification and treatment of waste water. However. the use of conventional TiO$_2$ powder photocatalyst results in disadvantage of stirring during the reaction and of separation after the reaction. And the usage of artificial UV lamp has made the cost of photocatalyst treatment system high. Consequently, we herein studied the pilot-scale design to aid in optimization of the energy-saving process for more through development and reactor design by solar light/UV lamp/ TiO$_2$system. In this study, we manufactured the TiO$_2$sol by sol-gel method. According to analysis by XRD, SEM and TEM, characterization of TiO$_2$ sol were nano-size (5-6 nm) and anatase type. Inorganic binder (SiO$_2$) was added to TiO$_2$ lot to be coated for support strongly, and support of ceramic bead was used to lower separation rate that of glass bead The influences were studied of various experimental parameters such as TiO$_2$ quantity, pH, flow rate. additives, pollutants concentration, climate condition and reflection plate by means of reaction time of the main chararteristics of the obtained materials. In water treatment system, variable realtor as solar light/ or UV lamp according to climate condition such as sunny and cloudy days treated the phenol and E-coli(Escherichia coli) effectively.

• Clean Technology
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• v.17 no.2
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• pp.142-149
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• 2011

The adsorption and desorption behaviors of NO and $N_2O$ over two mixed oxide catalysts, AlCoPd (1/1/0.05) and AlCoFe (1/1/2), have been investigated for the lean $NO_x$ trap applications. The catalysts showed good adsorption capabilities for NO and $N_2O$ without needing oxidation step. The adsorption decreased a lot when they are co-adsorbed with oxygen. While NO kept high adsorbability and selectivity with respect to oxygen, those of $N_2O$ decreased sharply. From the TPD results, NO and $N_2O$ are considered to decompose into nitrogen and oxygen in the higher temperature range and the oxygen seems to be strongly attached to the catalysts even at high temperature.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.26 no.8
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• pp.602-607
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• 2013

Concern for the TOS (Transparent Oxide Semiconductor) is increasing with the recent increase in interest for flexible device. Especially MgZnO has attracted a lot of attention. $Mg_xZn_{1-x}O$, which ZnO-based wideband-gap alloys is tuneable the band-gap ranges from 3.36 eV to 7.8 eV. In particular, the flexible substrate, the crystal structure of the amorphous as well as the surface morphology is not good. So research of MgZnO thin films growth on flexible substrate is essential. Therefore, in this study, we studied on the effects of the oxygen partial pressure on the structural and crystalline of $Mg_{0.1}Zn_{0.9}O$ thin films. MgZnO thin films were deposited on PES substrate by using pulsed laser deposition. We used XRD and AFM in order to observe the structural characteristics of MgZnO thin films. UV-visible spectrophotometer was used to get the band gap and transmittance. Crystallization was done at a low oxygen partial pressure. The crystallinity of MgZnO thin films with increasing temperature was improved, Grain size and RMS of the films were increased. MgZnO thin films showed high transmittance over 80% in the visible region.

• Journal of Energy Engineering
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• v.26 no.1
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• pp.1-8
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• 2017

This study was carried out to physicochemical properties and free CaO contents of coal ash in domestic circulating fludized bed combustion power plant using ethylene glycol method. Results of physicochemical properties, there are many differences in CaO contents for the region position in CFBC plant. The reason, It is considered to be reflected that regulation of exhaust concentration for oxides of sulfur and other operation characteristics of region position in CFBC plant. Free CaO contents are 1.96 ~ 10.78% of fly ash and 0.07~4.24 % of bottom ash, fly ash is higher than in the bottom ash. besides CaO contents of raw materials, particle distribution have a lot of influence Free CaO contents.

• 제어로봇시스템학회:학술대회논문집
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• 1997.10a
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• pp.69-72
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• 1997

A universal controller is designed using a DSP (digital signal processor). The design objectives of the system are to implement control algorithms that require a lot of calculations and to develop a convenient user-interface environment. To demonstrate the efficiency of the system, the time delay control algorithm is implemented for the 2 D.O.F.SCARA type robot and the experimental results are presented.

• Korean Management Science Review
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• v.21 no.2
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• pp.1-14
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• 2004

This paper presents a review on the operations research modeis for environmental management including water, land, and air poliution in the environmental chain and including waste treatment, reverse logistics, and product recovery in the supply chain for last 30 years. The integrated and globalized environmental issues have given OR professionals a lot of natural opportunities for an effective environmental management with mathematical programming and computer simulation tool.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.2056-2057
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• 2007

Recently we installed inverter system in $ind{\acute{u}}ction-m{\acute{o}}tor$ for the energy saving. But inverter system generates harmonics, and it causes a lot of issues. malfunction of meter, damage of instrument, overheating of motor. In this study, you can see how to deal with harmonics of inverter system by diagnosis of the power quality.