Hydrogen production by auto-thermal reforming of ethanol over nickel catalyst supported on metal oxide-stabilized zirconia

Youn, M.H.,Seo, J.G.,Song, I.K. Pergamon Press ; Elsevier Science Ltd 2010 International journal of hydrogen energy Vol.35 No.8

Metal oxide-stabilized mesoporous zirconia supports (M-ZrO<SUB>2</SUB> with different metal oxide stabilizer (M = Zr, Y, La, Ca, and Mg) were prepared by a templating sol-gel method. 20 wt% Ni catalysts supported on M-ZrO<SUB>2</SUB>(M = Zr, Y, La, Ca, and Mg) were then prepared by an incipient wetness impregnation method for use in hydrogen production by auto-thermal reforming of ethanol. The effect of metal oxide stabilizer (M = Zr, Y, La, Ca, and Mg) on the catalytic performance of supported nickel catalysts was investigated. Ni/M-ZrO<SUB>2</SUB>(M = Y, La, Ca, and Mg) catalysts exhibited a higher catalytic performance than Ni/Zr-ZrO<SUB>2</SUB> because surface oxygen vacancy of M-ZrO<SUB>2</SUB>(M = Y, La, Ca, and Mg) and reducibility of Ni/M-ZrO<SUB>2</SUB>(M = Y, La, Ca, and Mg) were enhanced by the addition of lower valent metal cation. Hydrogen yield over Ni/M-ZrO<SUB>2</SUB>(M = Zr, Y, La, Ca, and Mg) catalyst was monotonically increased with increasing both surface oxygen vacancy of M-ZrO<SUB>2</SUB>support and reducibility of Ni/M-ZrO<SUB>2</SUB>catalyst. Among the catalysts tested, Ni catalyst supported on yttria-stabilized mesoporous zirconia (Ni/Y-ZrO<SUB>2</SUB> showed the best catalytic performance.

Relationship Between K_trans and K₁ with Simultaneous Versus Separate MR/PET in Rabbits with VX2 Tumors

Lee, K. H.,Kang, S. K.,Goo, J. M.,Lee, J. S.,Cheon, G. J.,Seo, S.,Hwang, E. J. INTERNATIONAL INSTITUTE OF ANTICANCER RESEARCH 2017 Anticancer research Vol.37 No.3

<P>Background/Aim: To compare the relationship between Ktrans from DCE-MRI and K1 from dynamic (NNH3)-N-13- PET, with simultaneous and separate MR/PET in the VX-2 rabbit carcinoma model. Materials and Methods: MR/PET was performed simultaneously and separately, 14 and 15 days after VX-2 tumor implantation at the paravertebral muscle. The Ktrans and K-1 values were estimated using an in-house software program. The relationships between Ktrans and K-1 were analyzed using Pearson's correlation coefficients and linear/non-linear regression function. Results: Assuming a linear relationship, Ktrans and K-1 exhibited a moderate positive correlations with both simultaneous ( r=0.54-0.57) and separate ( r=0.53-0.69) imaging. However, while the Ktrans and K-1 from separate imaging were linearly correlated, those from simultaneous imaging exhibited a non-linear relationship. The amount of change in K-1 associated with a unit increase in Ktrans varied depending on Ktrans values. Conclusion: The relationship between K-trans and K-1 may be mis-interpreted with separate MR and PET acquisition.</P>

灌漑用水路의 水路損失率 算定에 관한 硏究

李基春,具滋雄,金在英,李宰泳,徐元明 전북대학교 농업과학기술연구소 1982 農大論文集 Vol.13 No.-

This study was carried out in order to estimate water losses in irrigation canals, which may be used to evaluate the water requirement for irrigation projects. The conveyance losses were measured by the inflow-outflow method, the seepage were measured by the ponding method, and the operation losses in the course of irrigation were calculated by comparing the two kinds of losses. The results obtained in this experiment were as follows : Conveyance losses per unit area of wetted perimeter per second by the main irrigation canal, the secondary irrigation canal and the tributary irrigation, canal, were 1.399x10-5m3/m3/sec, 5.154x10-5m3/m3/sec, and 2.670×10-5m3/m3/sec respectively in the Goong-sa area. And they were 1.934x10-5m3/m3/sec, 2.149x10-5m3/m3/sec, and 4.558x10-6m3/m3/sec respectively in the Seong-dug area. Seepage losses per unit area of wetted perimeter per second by the secondary irrigation canal and the tributary irrigation canal, were 2.180×10-6m3/m3/sec and 2.168×10-6m3/m3/sec in the Goons-sa area. 1.150x10-6m3/m3/sec and 1.084x10-6m3 /m3/sec in the Seong-dug area respectively. Operation losses per unit area of wetted perimeter per second by the secondary irrigation canal and the tributary irrigation canal, were 4.936×10-5m3/m3/sec and 2.453×10-5m3/m3/sec in the Goong-sa area, 2.034×10-5m3/m3/sec and 4.450×10-5m3/m3 /sec in the Seong-dug area respectively. Conveyance, seepage and operation losses in the Goong-sa area were 6.7%, 94.6%, and 14.0% more than those in the Seong-dug area. Operation losses amount to about 17 times as much as seepage losses in the Goons-sa area and about 29 times in the Seong-dug area .The seepage losses depend much on the soil texture. ranging from 7.437×10-7m3/m3/sec to 2.430x10-6 m3/m3/sec. Water loss rates in the main irrigation canal, the secondary irrigation canal and the tributary irrigation canal, were estimated as 8.49%. 37.27%, and 9.8l%, respectively in the Goong-sa area. And they were estimated as 15.10%, 32.67% and 13.73% respectively in the Seong-dug area.

Synthesis and Thermoelectric Properties of Ce1−z Pr z Fe4−x Co x Sb12 Skutterudites

Song, K. M.,Shin, D. K.,Jang, K. W.,Choi, S. M.,Lee, S.,Seo, W. S.,Kim, I. H. Springer Science + Business Media 2017 Journal of electronic materials Vol.46 No.5

<P>p-Type Ce1-z Pr (z) Fe4-x Co (x) Sb-12 skutterudites were prepared by encapsulated melting, quenching, annealing, and hot pressing. While the skutterudite phase was successfully synthesized, a small amount of the secondary phase (FeSb2) was observed. According to the scanning electron microscope analysis, (Ce,Pr)Sb-2 phases were also observed for Co-substituted specimens (x = 0.5). The electrical conductivity decreased with increasing temperature, implying a degenerate semiconductor behavior, and also decreased with increasing Co contents. All specimens showed p-type characteristics having positive signs of the Hall coefficient and the Seebeck coefficient. The Seebeck coefficient increased with increasing temperature and reached a maximum value at 823 K. The power factor (PF) increased with decreasing Co content and Ce0.75Pr0.25 Fe4Sb12 showed a peak value of PF = 3.2 mW m(-1) K-2 at 823 K. The electronic thermal conductivity decreased with increasing Co contents and the lattice thermal conductivity decreased with decreasing Ce and Co contents at high temperature. The thermal conductivity increased at temperatures above 623 K due to bipolar conduction. The dimensionless figurea of pound merit (ZT) showed a maximum value of ZT = 0.84 at 823 K for Ce0.25Pr0.75Fe4Sb12.</P>

고온기 초지의 예취관리에 관한 연구 6 . 고온기간중 예취높이와 질소 및 칼리추비가 혼파초지의 식생과 수량 및 목초품질에 미치는 영향

서성(S . Seo),조무환(M . H . Jo),박문수(M . S . Park),이종경(J . K . Lee),한영춘(Y . C . Han) 한국축산학회 1988 한국축산학회지 Vol.30 No.8

A field experiment was carried out to determine the effects of cutting height at the third cut and application of N and K₂O after cutting during mid-summer season on the soil temperature, plant height, grass coverage, percentages of grass and legume, yield and grass quality in orchardgrass dominated pasture. With three cutting heights (3, 6 and 9㎝) and 4 fertilizer levels (0, N 50㎏, K₂O 50㎏, and N 50㎏ + K₂O 50㎏ ㏊^(-1)), present experiment was conducted at Livestock Experiment Station, Suwon in 1987. 1. The soil temperature after the third cut was rapidly elevated, and lower value was observed with 9㎝ of cutting height through the regrowth period. Plant height after cutting was remarkably increased with higher stubble height regardless of fertilizer levels. 2. The grass coverage and percentage of grass were increased as stubble height was high, while the influence of fertilizer on those was very little. Application of N and K₂O with lower stubble height significantly increased the percentage of bareland. 3. The yield at the third cut was decreased with higher height. But the regrowth yield was significantly increased as the cutting height was increased regardless of fertilizer levels. Regrowth yield was great at N 50㎏ + K₂O 50㎏ $gt; 0 $gt; K₂O 50㎏, N 50㎏, in that order. However, there were not significantly different on regrowth yield among fertilizer treatment. 4. The contents of crude protein, crude fat, crude ash, P, K and Ca were decreased as stubble height was high, and that of crude fiber was increased at 9 ㎝ cutting height. Also the influence of N and K₂O fertilizer on grass quality was little.

Microstructure and piezoelectric properties of (Na_0.5K_0.5)NbO₃ lead-free piezoelectric ceramics with V₂O₅ addition

Seo, I.-T.,Park, H.-Y.,Dung, N.V.,Choi, M.-K.,Nahm, S.,Lee, H.-G.,Choi, B.-H. IEEE 2009 and Frequency Control Vol.56 No.11

<P>Various amounts of Nb<SUB>2</SUB>O<SUB>5</SUB> in the (Na<SUB>0.5</SUB>K<SUB>0.5</SUB>) NbO<SUB>3</SUB> (NKN) ceramic were replaced by V<SUB>2</SUB>O<SUB>5</SUB> to decrease its sintering temperature to below 950°C. A small V<SUB>2</SUB>O<SUB>5</SUB> content resulted in a dense microstructure with an increased grain size for the specimen sintered at 900°C due to the presence of a liquid phase. When V<SUB>2</SUB>O<SUB>5</SUB> was added to the NKN ceramics, their orthorhombic-to-tetragonal transition temperature increased from 178°C to around 200°C. However, their Curie temperature decreased from 402°C to around 330°C. The k<SUB>p</SUB>, <SUB>ε3</SUB> <SUP>T</SUP>/<SUB>ε0</SUB>, and Q<SUB>m</SUB> values increased with V<SUB>2</SUB>O<SUB>5</SUB> addition, probably due to the increased density and poling state, which was identified by the phase angle. The specimen with x = 0.05, sintered at 900°C for 8 h, exhibited the following piezoelectric properties: k<SUB>p</SUB> = 0.32, <SUB>ε3</SUB> <SUP>T</SUP>/<SUB>ε0</SUB> = 245, d<SUB>33</SUB> = 120 (pC/N), and Q<SUB>m</SUB> = 232.</P>

Triplet state and phosphorescence of hole-transport layer and its triplet exciton confinement

Seo, J.H.,Han, N.S.,Shim, H.S.,Park, S.M.,Kwon, J.H.,Song, J.K. North Holland ; Elsevier Science Ltd 2010 Chemical physics letters Vol.499 No.4

The triplet state of 4,4',4''-tris(3-methylphenylphenylamino)triphenylamine (m-MTDATA) and the dynamics of the singlet and the triplet states were examined to understand the confinement effect of m-MTDATA as host materials for phosphorescent organic light-emitting diodes. The time-resolved photoluminescence spectra revealed phosphorescence at approximately 480nm (2.58eV). The time constant of the T<SUB>1</SUB> state was 1.2μs. The dynamics of delayed fluorescence was closely related to that of phosphorescence. The triplet energy of a green phosphorescent sensitizer was well-confined in the m-MTDATA host, which suggests the application of m-MTDATA as possible host materials.

High-temperature thermoelectric properties of polycrystalline CaMn_1-<i>x</i>Nb_<i>x</i>O_3-δ

Seo, J.W.,Kim, G.H.,Choi, S.-M.,Park, K. Elsevier 2018 CERAMICS INTERNATIONAL Vol.44 No.8

<P><B>Abstract</B></P> <P>The structural and thermoelectric (TE) properties of polycrystalline CaMn<SUB>1-<I>x</I> </SUB>Nb<SUB> <I>x</I> </SUB>O<SUB>3-δ</SUB> (0.025 ≤ <I>x</I> ≤ 0.25) were studied with X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), and electrical transport measurements, with an emphasis placed on the Nb<SUP>5+</SUP> content. The CaMn<SUB>1-<I>x</I> </SUB>Nb<SUB> <I>x</I> </SUB>O<SUB>3-δ</SUB> crystallized in an orthorhombic perovskite structure of the <I>Pnma</I> space group. The density and grain size of the CaMn<SUB>1-<I>x</I> </SUB>Nb<SUB> <I>x</I> </SUB>O<SUB>3-δ</SUB> samples gradually decreased when Nb<SUP>5+</SUP> ions substituted Mn<SUP>4+</SUP> ions. The CaMn<SUB>0.95</SUB>Nb<SUB>0.05</SUB>O<SUB>3-δ</SUB> sample contained charge-ordered domains, stacking faults, and micro-twins. The substitution of Nb<SUP>5+</SUP> for Mn<SUP>4+</SUP> up to <I>x</I> = 0.15 led to an increase in electrical conductivity, mainly due to an increased electron concentration. The CaMn<SUB>1-<I>x</I> </SUB>Nb<SUB> <I>x</I> </SUB>O<SUB>3-δ</SUB> samples with low Nb<SUP>5+</SUP> contents (0.025 ≤<I> x</I> ≤ 0.15) showed metallic behavior, whereas those with high Nb<SUP>5+</SUP> contents (0.2 ≤<I> x</I> ≤ 0.25) showed semiconducting behavior. The Nb<SUP>5+</SUP> substitution lowered the absolute value of the Seebeck coefficient for the CaMn<SUB>1-<I>x</I> </SUB>Nb<SUB> <I>x</I> </SUB>O<SUB>3-δ</SUB> samples due to an increased electron concentration. The largest power factor (1.19 × 10<SUP>−4</SUP> W m<SUP>−1</SUP> K<SUP>−2</SUP>) was obtained for CaMn<SUB>0.95</SUB>Nb<SUB>0.05</SUB>O<SUB>3-δ</SUB> at 800 °C. The partial substitution of Nb<SUP>5+</SUP> for Mn<SUP>4+</SUP> in CaMnO<SUB>3-δ</SUB> proved to be highly effective for improving high-temperature TE properties.</P>

Existence of metastable molecular precursors to dissociative oxygen chemisorption on Si(111) and Si(100) at 40 K

Seo, J. M.,Kim, K. J.,Yeom, H. W.,Park, Ch. 全北大學校 基礎科學硏究所 1994 基礎科學 Vol.17 No.-

The presence of metastable molecular precursor to dissociative oxygen chemisorption has been identified, for the first time, on Si(100) and Si(111) surfaces using ultraviolet photoelectron spectroscopy and x-ray photoelectron spectroscopy at 40 K. Density of valence states for such species shows three distinct peaks at 1.8, 3.4, and 4.9 eV below the Fermi energy of substrates. The precursor stabilized on Si(100) at 40 K induces a large work- function increase of 1.5 eV at saturation coverage. It also gives rise to a shoulder to O 1s photoemission spectrum that it located at 1.2 eV lower binding energy than the O 1s peak of stable and dissociated oxygen species. It has been concluded that the major reason of a larger work-function increment at 40 K is the existence of a molecular precursor, or peroxy radical type, on Si(100) and Si(111). These results strongly suggest that exists a general mechanism of oxygen adsorption onto silicon surfaces.

A Design of Transferable Sample Holder for Resistive Heating and Conductive Cooling

Seo, J.M.,Kim, K.J.,Ihm, S.,Koo, S.J.,Park, Ch.,Kim, Y.K. 全北大學校 基礎科學硏究所 1994 基礎科學 Vol.16 No.-

통전가열, 접촉냉각, 전기적 bias 및 시료 교환을 자유로이 할 수 있는 다기능의 새롭고 간단한 시료 고정장치를 저온 및 초고진공 상태에서 기체와 여러 방향의 시료표면 사이의 상호작용을 연구하기 위하여 고안하였다. 이 장치로써 2분 이내에 기판의 온도를 1600 K에서 20 K로 2분 이내에 냉각시킬 수 있었다. 그러므로 청결한 표면위에 수소나 He이나 Ne을 제외하고는 대부분의 기체를 흡착시킬 수 있게 되었다. 이러한 장치는 표면에서의 상변화, 기체와 표면의 화학반응의 연구에 중요하게 활용될 수 있다. A simple and novel sample-holder which has multi-functions of resistive heating, conductive cooling, electrical biasing and sample exchanging has been designed in order to inverstigate gas-surface interations for various surface direction under ultrahigh vacuum and low temperature. It has been proved that the wafer can be cooled from 1600 K to 20 K within two minutes. Therefore the controlled adsorption of most gases, except H, He and Ne, were possible on the clean surfaces. The design has substantial applocations in areas like surface phase transitions and gas-surface chemical reactions.