• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.87-87
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• 2010

Photoelectrochemical (PEC) systems are promising methods of producing H2 gas using solar energy in an aqueous solution. The photoelectrochemical properties of numerous metal oxides have been studied. Among them, the PEC systems based on TiO2 have been extensively studied. However, the drawback of a PEC system with TiO2 is that only ultraviolet (UV) light can be absorbed because of its large band gap (3.2 - 3.4 eV). Two approaches have been introduced in order to use PEC cells in the visible light region. The first method includes doping impurities, such as nitrogen, into TiO2, and this technique has been extensively studied in an attempt to narrow the band gap. In comparison, research on the second method, which includes visible light water splitting in molecular photosystems, has been slow. Mallouk et al. recently developed electrochemical water-splitting cells using the Ru(II) complex as the visible light photosensitizer. the dye-sensitized PEC cell consisted of a dye-sensitized TiO2 layer, a Pt counter electrode, and an aqueous solution between them. Under a visible light (< 3 eV) illumination, only the dye molecule absorbed the light and became excited because TiO2 had the wide band gap. The light absorption of the dye was followed by the transfer of an electron from the excited state (S*) of the dye to the conduction band (CB) of TiO2 and its subsequent transfer to the transparent conducting oxide (TCO). The electrons moved through the wire to the Pt, where the water reduction (or H2 evolution) occurred. The oxidized dye molecules caused the water oxidation because their HOMO level was below the H2O/O2 level. Organic dyes have been developed as metal-free alternatives to the Ru(II) complexes because of their tunable optical and electronic properties and low-cost manufacturing. Recently, organic dye molecules containing multi-branched, multi-anchoring groups have received a great deal of interest. In this work, tri-branched tri-anchoring organic dyes (Dye 2) were designed and applied to visible light water-splitting cells based on dye-sensitized TiO2 electrodes. Dye 2 had a molecular structure containing one donor (D) and three acceptor (A) groups, and each ended with an anchoring functionality. In comparison, mono-anchoring dyes (Dye 1) were also synthesized. The PEC response of the Dye 2-sensitized TiO2 film was much better than the Dye 1-sensitized or unsensitized TiO2 films.

• Journal of the Korean Chemical Society
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• v.51 no.2
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• pp.178-185
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• 2007

Intermediate pentasil borosilicate zeolite-like materials have been crystallized by a novel method named steam-assisted conversion, which involves vapor-phase transport of water. Indeed, amorphous powders obtained by drying Na2O.SiO2.B2O3.TBA2O gels of various compositions using different boron sources are transformed into crystalline borosilicate zeolite belonging to pentasil family structure by contact with vapors of water under hydrothermal conditions. Using a variant of this method, a new material which has an intermediate structure of MFI/MEL in the ratio 90:10 was crystallized. The results show that steam and sufficiently high pH in the reacting hydrous solid are necessary for the crystallization to proceed. Characterization of the products shows some specific structural aspects which may have its unique catalytic properties. X-ray diffraction patterns of these microporous crystalline borosilicates are subjected to investigation, then, it is shown that the product structure has good crystallinity and is interpreted in terms of regular stacking of pentasil layers correlated by inversion centers (MFI structure) but interrupted by faults consisting of mirror-related layers (MEL structure). The products are also characterized by nitrogen adsorption at 77 K that shows higher microporous volume (0.160 cc/g) than that of pure MFI phase (0.119 cc/g). The obtained materials revealed high surface area (~600 m2/g). The infrared spectrum reveals the presence of an absorption band at 900.75 cm-1 indicating the incorporation of boron in tetrahedral sites in the silicate matrix of the crystalline phase.

• Korean Journal of Soil Science and Fertilizer
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• v.6 no.4
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• pp.245-251
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• 1973

Effects of lime and inoculation on dry matter yield and nutrient contents of three alfalfa varieties (Medicago sativa L. var. Moapa, Washoe and Lahontan) were investigated with pot culture using Red-yellow sandy loam soil (pH 4.9, from Ryogi hill) 1. In no lime plot germination was poor and harvest was nil, but Moapa was stronger than others. 2. Dry matter yield in uninoculation plot was Moapa>Washoe>Lahontan and effect of inoculation was reverse but nodule development was not clear by inoculation. 3. Dry matter yield in uninoculated plot tends to increase with cutting but effect of inoculation to decrease and the same in nitrogen content in herbage. 4. Moapa was higher in the content of N, Ca, Mg and lower in P, K than Washoe and Lahontan. 5. Washoe was higer in K and Mg and lower in P and Ca than Lahontan. 6. The content of microelements (Fe, Mn and Zn) tends to increase by inoculation and the content of P and K decreased with cutting. 7. High yielding capacity of Moapa seems to be attributable to strong absorption power of N, Ca, Mg and low requirement of P,K.

• Journal of Animal Science and Technology
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• v.47 no.3
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• pp.397-408
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• 2005

This study, consisting of three experiments, was conducted to determine the effects of feeding feather meal (FM), feather meal digest (FMD), L-cystine and methionine hydroxyl analogue (MHA) on taurine content of milk and milk production of Holstein dairy cows. In experiment 1, FM or FMD was supplemented at 0, 1, 3 and 5% of dry matter intake (DMI), respectively. Taurine concentration of 3% FM and 5% FMD treatment were increased by 14% and 220/0, respectively. The 5% FM treatment had a negative effect on milk yield and FM and FMD treatments had no significant or consistent effects on milk fat, protein, lactose, milk urea nitrogen (MUN) and somatic cell count (SCC). In experiment 2, Lcystine or MHA was supplemented at 0, 1, 3, and 5g or ml/d along with 5% FMD, respectively. Milk yield decreased at 3 and 5g or ml Lcystine or MHA supplementation along with 5% FMD. Fat and lactose in milk were not significantly affected by treatments. However, milk protein level increased significantly in the 5 ml HMA with 5% FMD treatment. SCC decreased significantly in 1ml MHA with 5% FMD supplemented treatment but increased in 5g Lcystine with 5% FMD and 5 ml MHA with 5% FMD treatments. Increase of milk taurine concentration of L'cystine with 5% FMD treatments was not significant but those of MHA with 5% FMD treatments were significantly higher than the control. The highest increase of milk taurine concentration was 65% shown in 1 ml MHA with 5% FMD treatment. In experiment 3, 5% FM, 5% FM+3% molasses or 5% FM+3% molasses+l ml MHA was supplemented to the based TMR diet. The molasses treatments (5% FM+3% molasses and 5% FM+3% molasses+l ml MHA) showed significantly higher milk taurine content than the 5% FM treatment. The molasses treatments significantly reduced MUN but increased SCC. It was concluded that FMD is more effective than FM in enriching taurine in milk. Maximum taurine enrichment (65%) in the milk was obtained by supplementation of 5% FMD/DM1+1 ml MHA/d/cow. Molasses supplementation to 5% FM diet increased milk taurine content. However, MHA supplementation in dairy cows increased ruminal escape, gastrointestinal absorption and response of serum methionine.

• Korean Journal of Soil Science and Fertilizer
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• v.26 no.4
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• pp.304-307
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• 1993

An experiment was conducted to evaluate the effects of silicate and potassium application on the yield of rice irrigated with polluted water and ground water. 1. The most important component affecting plant growth in polluted water was $NH_4-N$. 2. Rice grain yield was increased by silicate and potassium application, and yield increase of silicate and potassium was higher than that of single application of silicate and potassium. 3. The ratios of $SiO_2$/T-N and $K_2O$/T-N in shoot of rirc plant increased with silicate and potassium application, but the absorption of nitrogen by rice plant was decreased. 4. Lodging index was increased by the application of polluted water, and the application of silicate and potassium reduced the lodging.

• Korean Journal of Materials Research
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• v.20 no.11
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• pp.586-591
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• 2010

Solar cells have been more intensely studied as part of the effort to find alternatives to fossil fuels as power sources. The progression of the first two generations of solar cells has seen a sacrifice of higher efficiency for more economic use of materials. The use of a single junction makes both these types of cells lose power in two major ways: by the non-absorption of incident light of energy below the band gap; and by the dissipation by heat loss of light energy in excess of the band gap. Therefore, multi junction solar cells have been proposed as a solution to this problem. However, the $1^{st}$ and $2^{nd}$ generation solar cells have efficiency limits because a photon makes just one electron-hole pair. Fabrication of all-silicon tandem cells using an Si quantum dot superlattice structure (QD SLS) is one possible suggestion. In this study, an $SiO_x$ matrix system was investigated and analyzed for potential use as an all-silicon multi-junction solar cell. Si quantum dots with a super lattice structure (Si QD SLS) were prepared by alternating deposition of Si rich oxide (SRO; $SiO_x$ (x = 0.8, 1.12)) and $SiO_2$ layers using RF magnetron co-sputtering and subsequent annealing at temperatures between 800 and $1,100^{\circ}C$ under nitrogen ambient. Annealing temperatures and times affected the formation of Si QDs in the SRO film. Fourier transform infrared spectroscopy (FTIR) spectra and x-ray photoelectron spectroscopy (XPS) revealed that nanocrystalline Si QDs started to precipitate after annealing at $1,100^{\circ}C$ for one hour. Transmission electron microscopy (TEM) images clearly showed SRO/$SiO_2$ SLS and Si QDs formation in each 4, 6, and 8 nm SRO layer after annealing at $1,100^{\circ}C$ for two hours. The systematic investigation of precipitation behavior of Si QDs in $SiO_2$ matrices is presented.

• Journal of the Korean Vacuum Society
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• v.20 no.5
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• pp.361-366
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• 2011

An in-situ, real-time monitoring of GaN epilayers grown by low pressure metalorganic chemical vapor deposition system modified for spectral reflectance was performed. Reflectance spectrums from 190~861 nm were observed using p-polarized light with incident angle of $75^{\circ}$. All reflectance spectrums showed interference oscillation caused by multiple reflection within GaN epilayers, and the spectrum from GaN with low crystalline quality showed weak reflectance intensity and much low amplitude of the oscillation because many defects in GaN resulted in light scattering and absorption. Signal variation of reflected light which was selected around strong constructive wavelength range was also observed during $NH_3$ supplying and $NH_3$ cut-off. There was no significant change in signal intensity when $NH_3$ cut-off for 10 sec, but it showed higher intensity when $NH_3$ was cut off for over 30 sec and its intensity kept unchanged. This result indicates that GaN surface was N-terminated during $NH_3$ supplying but Ga-terminated during $NH_3$ cut-off because of high nitrogen equilibrium vapor pressure of GaN, and metallic Ga-terminated surface caused slightly higher reflectance intensity.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.31 no.4
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• pp.465-469
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• 1986

This study was conducted to investigate the proper fertilizer application level and top-dressing method of Lycium chinense MILL in 1984 and 1985. The results obtained were summerized as follows; Stem length was 4cm longer, leaf area was 45-490$\textrm{cm}^2$ larger, dry matter weight per plant was 1.6-5g heavier and average yield of dry fruit of two years was higher as 183kg per l0a in double amount of potassium( 14kg/l0a) application than in standard level of potassium(7kg/l0a). Highly positive correlation was found between absorption amount of inorganic elements of phosporus(l%), nitrogen, potassium(5%) and dry matter weight. Proper fertilizer application level was 13.8kg(N), 14.2kg(P) and 14.3kg(K) per l0a. Dry fruit yield of top-dress-ing plot was 20% heigher than that of basal dressing plot through increase of leaf area per plant and dry matter weight per plant.

• Applied Biological Chemistry
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• v.15 no.3
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• pp.229-240
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• 1972

Not only in order to determine reasonable application amounts of PCP in terms of soil texture, but also to get basic data for fish-toxicity-free treatment by estimating fish toxicity, some aspects of PCP adsorption were observed taking various paddy soils with different physico-chemical characteristics in the Choongbook Area as samples. The results obtained are summarized as follows: 1. There was a positive correlation between PCP adsorption and clay contents, total nitrogen, organic matter, cation exchange capacity, exchangeable bases, and phosphorus absorption coefficients, respectively; whereas there was a negative one between PCP adsorption and pH. Although they were not significant, it was remarkable that there was a relatively large amount of correlation between PCP adsorption and clay contents, $H^+,\;Mg^{++}$, and CEC, respectively. 2. PCP adsorption in terms of soil texture was in the order of Clay>Loam>Sandy loam. 3. Although PCP adsorption in the $H_2O_2-treated$ soils decreased remarkably, it was not proportional to the humus contents. 4. The order of PCP adsorption in the exchangeable base-treated soils was H^+-exchanged soil>$K^+-soil$>$Na^+-soil$>$Ca^{++}-soil$>Mg^{++}-soil. 5. Langmuir's and Freundlich's adsorption isotherms were applicable to the PCP adsorption, and thereby were able to be calculated maximum adsortion amounts of PCP, bond energy, and the depths of adsorption layers. 6. Maximum adsorbed amounts of PCP were 212.14 mg/100gr in Clayey loam, 97.28 to 121.59mg/100gr in Loam, and 32.92 to 91.74mg/100gr in Sandy loam, respectively. 7. The depths of mixed layers of limiting application for fish-toxicity-free treatment were 0.88cm of the Jinchun soil, the shallowest and 4.29 cm of the Naesan-ri Sandy loam, the deepest.

• Microbiology and Biotechnology Letters
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• v.46 no.2
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• pp.120-126
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• 2018

As a basic study for environment-friendly production of bacterial cellulose (BC) dressing with antimicrobial activity, we isolated and identified acetic acid bacteria which are resistant to silver ions and can biosynthesize silver nanoparticles. Furthermore, conditions of BC production by selected strain were also investigated. Strain G7 isolated from decayed grape skin was able to grow in the presence of 0.1 mM $AgNO_3$ which was identified as Acetobacter intermedius based on 16S rRNA gene analysis. BC production was the highest in a medium containing 2% glucose as a carbon source, 2% yeast extract as a nitrogen source, and 0.115% acetic acid as a cosubstrate. Structural properties of BC produced in optimal medium were studied using Fourier-transform infrared spectroscopy and X-ray diffractometer, and it was found that BC produced was cellulose type I that was the same as a typical native cellulose. When strain G7 was cultured in an optimal medium containing 0.1 mM $AgNO_3$, the color of the culture broth turned into reddish brown, indicating that silver nanoparticles were formed. As a result of UV-Vis spectral analysis of the culture, it was found that a unique absorption spectrum of silver nanoparticles at 425 nm was also observed. Scanning electron microscopic observations showed that silver nanoparticles were formed on the surface and pores of BC membrane.