• Nano
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• v.13 no.11
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• pp.1850130.1-1850130.12
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• 2018

A novel strontium titanate/binary metal sulfide ($SrTiO_3/SnCoS_4$) heterostructure was synthesized by a simple two-step hydrothermal method. The visible-light-driven photocatalytic performance of $SrTiO_3/SnCoS_4$ composites was evaluated in the degradation of methyl orange (MO) under visible light irradiation. The photocatalytic performance of $SrTiO_3/SnCoS_4-5%$ is much higher than that of pure $SrTiO_3$, $SnCoS_4$, $SrTiO_3/SnS_2$ and $SrTiO_3/CoS_2$. The $SrTiO_3/SnCoS_4$ composite material with 5 wt.% of $SnCoS_4$ showed the highest photocatalytic efficiency for MO degradation, and the degradation rate could reach 95% after 140 min irradiation time. The enhanced photocatalytic activity was ascribed to not only the improvement of visible light absorption efficiency, but also the construction of a heterostructure which make it possible to effectively separate photoexcited electrons and holes in the two-phase interface.

• Journal of the Korean Electrochemical Society
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• v.11 no.3
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• pp.135-140
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• 2008

An electrochemical generation of ozonized water was investigated by using ${\beta}-PbO_2$ as an anode and tap water as an anolyte. According to the potentiometric ozone detection which utilizes potential differences arisen from a chemical reaction of ozone and iodide, increasing tendency of ozone concentration on electrolysis time could be observed to show the maximum value of 8 ppm at an electrolysis time of 10 min. Ozone could be generated promptly even at an electrolysis time of 10 sec., suggesting great advantages of this electrochemical process in terms of simplicity and readiness that might be applied directly to practical uses including medical and/ or food industries. Influences of electrolysis on the properties and surface conditions of a $PbO_2$ electrode were also discussed from the results of cyclic voltammetry, scanning electron microscope, and X-ray diffractometer.

• Proceedings of the Korea Association of Crystal Growth Conference
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• 1997.06a
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• pp.149-155
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• 1997

We have successfully grown colorless and transparent Rb-doped potassium niobate (KRN) single crystals using the top seeded solution growth(TSSG) technique. In our crystal growth experiments, the Rb doping concentrations within the melt range from 2-15 mol% relative to that of Nb$_2$O5. Atomic absorption measurements indicate that the Rb content in the KRN solid solution is rather low; the Rb segregation coefficient is found to be on the order of 0.05. It is believed that this is due to the relatively much larger Rb+ ionic radius compared to that of K+, rendering it more difficult for Rb to replace K in the KNbO$_3$(KN) host lattice. Preliminary single-pass second harmonic generation (SHG) experimental results indicate that there exists marginal improvement in the phase-matching temperature tolerance of KRN compared to that of pure Kn single crystals.

• Journal of Korean Society for Atmospheric Environment
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• v.17 no.1
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• pp.97-104
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• 2001

Decomposition of trichloroethlyene(TCE) in electron beam irradiation was examined on order to obtain information on the treatment of VOC in air. Air containing vaporized TCE has been studied in a flow reactor with different reaction environments, at various initial TCE concentration and in the presence and absence of water vapor. Maximum decomposition was observed in oxygen reaction environment and the degree of decomposition was about 99% at 20kGy for 2,000ppm initial TCE. The concentration of TCE exponentially decreased with dose in air and pure oxygen. The effect of water vapor on TCE decomposition efficiency was examined. The decomposition rate of TCE in the presence of water vapor (5,600 ppm) was approximately 10% higher than that in the absence of water vapor. Dichloroacetic acid, dichloroacethyl chloride and dichloroethyl ester acid were identified as primary products of this reaction adn were decomposed and oxidized to yield CO and $CO_2$. Perchloroethylene, hexachloroethane, chloroform and carbon tetrachloride were also observed as highly chlorinat-ed by products.

• 한국정보디스플레이학회:학술대회논문집
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• 2004.08a
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• pp.973-974
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• 2004

We report the fabrication of flexible plastic ITO substrates and the measurement of oxidant permeation through the substrates. The plastic ITO substrates are composed of multiple organic and inorganic thin films. The organic thin films are deposited by vapor polymerization and the inorganic films are deposited by ion beam sputtering. In order to estimate the oxidant permeation rate, the pure Ca film is formed on the substrates and the amount of CaO produced by the oxidation of Ca is measured.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2001.10a
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• pp.169-173
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• 2001

This study presents the results of decoupling of free decay roll test data by discrete wavelet transform. Free roll decay test was performed to decide the coefficients of damping terms in equation of motion. During the experiment, a slight yaw motion was found while the model was in the free roll decay motion. Discrete wavelet transform was applied to the signal to extract the pure roll motion. The results were compared to those of the Fourier transform. DWT was able to decouple the two signals efficiently while the Fourier transform was not.

• Transactions of the Korean hydrogen and new energy society
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• v.17 no.4
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• pp.454-460
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• 2006

In the production of hydrogen from various sources like cracking of LPG, LNG, Crude oil, or alkaline water electrolysis, the things that we keep in mind is the entrapment of unexpected impurities in the stream of produced $H_2$. If it is true that we are not able to produce 100% pure $H_2$, then subsequent procedure is the elimination of the impurities and the determination of the concentrations of each constituents in $H_2$ stream. By the way, each country has different constituents in its fuels and unavoidablely it was cost/economy debates between coutries. Thus, in this paper, our goal is to provide current international issues for hydrogen production.

• KSBB Journal
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• v.16 no.1
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• pp.95-98
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• 2001

Various factors affecting the supercritical carbon dioxide extraction of daidzein from soybean were studied. Daidzein was not extracted with pure supercritical carbon dioxide. The ethanol was an efficient modifier for supercritical carbon dioxide to extract daidzein. The extraction efficiency increased as the pressure increased up to 300 bar. At $35^{\circ}C$ and 300 bar, 93% of daidzein was extracted with supercritical carbon dioxide modified with 15% of ethanol.

• Management Science and Financial Engineering
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• v.16 no.2
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• pp.53-65
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• 2010

Despite the overall success of neighbor-based CF methods, there are some fundamental questions about neighbor selection and prediction mechanism including arbitrary similarity, over-fitting interpolation weights, no trust consideration between neighbours, etc. This paper proposes a simple method to compute absolute interpolation weights based on similarity values. In order to supplement the method, two schemes are additionally devised for high-quality neighbour selection and trust metrics based on co-ratings. The former requires that one or more neighbour's similarity should be better than a pre-specified level which is higher than the minimum level. The latter gives higher trust to neighbours that have more co-ratings. Experimental results show that the proposed method outperforms the pure IBCF by about 8% improvement. Furthermore, it can be easily combined with other predictors for achieving better prediction quality.

• Korean Journal of Pharmacognosy
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• v.20 no.4
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• pp.205-214
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• 1989

The sensing of odour compounds in gas phase is an attractive target in recent sensor technology. Based on the finding that a plant leaf can respond to various gas molecules by changing its potential, biosensing system using a plant leaf has been investigated for the detection of odour compounds. A leaf of some plant species responded to odour compounds directly by changing its potential $5{\sim}10\;mV$. That the leaf was actually sensing an odour was much more remarkably detected from the difference between the response profile to pure $CO_2$ gas and that to $CO_2$ gas containing odour compounds. Then the quantitative study (ppb level) is now being performed on the response of a tobacco leaf to benzyl acetate; a component of jasminelike odours. The concept of biosensing and its significance are also described from the viewpoint of sensor technology.