• Korean Journal of Soil Science and Fertilizer
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• v.31 no.2
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• pp.114-119
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• 1998

Intensity and stability of the blue color of phospho-molybdate complex in P analysis are known to be influenced by the matrix, reducing regent and acidity of the extractants. Objective of this research was to compare the efficiency of the color-developing reagents for P concentrations in distilled water and extracts of Lancaster, Mehlich II, and Mehlich III methods. Efficiencies on which to base this study were evaluated by the optimum ranges of P, reproducibility of calibration curve and stability of the developed color. Color-developing reagents employed were ammonium molybdate-1,2,4- aminonaphtholsulfonic acid (ANS), ammonium molybdate-ascorbic acid-bismuth subcarbonate (AB), and ammonium molybdate-ascorbic acid-antimony potassium tartarate (AA). The ANS revealed the lowest sensitivity but the widest ranges for P concentrations in color development. On the other hand, the AA bore the narrowest color-developing ranges and its sensitivity was similar to AB. However, at P concentrations lower than $0.5mg\;L^{-1}$, AA was more sensitive than AB. Based on the data on the ranges of calibration curve, stability of color and reproducibility of analytical data. AA reagent was considered to be suitable for the determination of P in distilled water and AB reagent was practically recommendable for soil P analysis in extracts by Lancaster, Mehlich II, and Mehlich III procedures.

• Journal of the Korean Ceramic Society
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• v.45 no.5
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• pp.290-296
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• 2008

$AB'_{0.5}B"_{0.5}O_3$ type complex perovskite structures which have been reported as proton conductors over $600^{\circ}C$ were studied. The $AB'_{0.5}B"_{0.5}O_3$ type complex perovskite structure is known to be more easily synthesized and has better stability than normal $ABO_3$ perovskite structure. And it is stable at about $800^{\circ}C$ in the $CO_2$ atmosphere, whereas the $BaCeO_3$ perovskite is easily decomposed into carbonate. In addition, this $AB'_{0.5}B"_{0.5}O_3$ type complex perovskite structure could simply produce oxygen vacancies within their structure not by introducing additional doping oxides but by just controling the molar ratio of $B'^{+3}$ and $B"^{+5}$ metal ions in the B site. Hence it is easy to design the structure which shows highly sensitive electrical conductivity to humidity. In this study, the single phase boundary of $BaR_{0.5+x}Ta_{0.5-x}O_{3-{\delta}}$(R = rare earth) complex perovskite structures and it's phase stability were investigated with changes in composition, x. And the humidity dependance of electrical conductivity at different $P_{H2O}$ conditions was investigated.

• Journal of the Korean Chemical Society
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• v.28 no.4
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• pp.217-230
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• 1984

The MINDO/3 method was used in determination of transition states and activation barriers for various 1,2-, 1,3- and 1,5-sigmatropic hydrogen rearrangements involving systems with central carbon atom. It was found that, besides the consideration of orbital symmetry, steric effect, aromaticity, and orbital interactions were found to dictate the stability of the transition state. For systems with hetero atoms, lone pair orbitals tend to ease orbital distortion required at the transition state by participating in hydrogen transfer process and were found to lower the activation barrier accordingly. Comparison of the relative barrier heights with those obtained by using more sophisticated ab initio MO calculations showed that the MINDO/3 results give qualitatively the same tendency of the relative order of the activation barriers.

• Journal of Korean Society of Environmental Engineers
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• v.35 no.4
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• pp.247-256
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• 2013

In this study, alginate beads containing birnessite (Bir-AB), a highly reactive oxidative catalyst for the transformation of phenolic compounds, was prepared and its 1-naphthol (1-NP) removal efficiency was investigated in a batch test. Based on scanning electron microscopy image, it can be inferred that the alginate gel cluster acts as a bridge which bind the birnessite particles together. Kinetic experiment with Bir-AB of different mixing ratios of birnessite to alginate (Bir : AG=0.25 : 1~1 : 1 w/w) indicate that pseudo-first order kinetic constants, $k(hr^{-1})$ for the 1-NP removals increased about 1.5 times when the birnessite mixing ratio was doubled. The removals of 1-NP was found to be dependent on solution pH and the pesudo-first order rate constants were increased from 0.331 $hr^{-1}$ at pH 10 to 0.661 $hr^{-1}$ at pH 4. The analysis of total organic carbon for the reaction solutions showed that a higher removal of dissolved organic carbon was achieved with Bir-AB as compared to birnessite. HPLC chromatographic analysis of the methanol extract after reaction of 1-NP with Bir-AB suggest that the reaction products could be removed through incorporation into the aliginate beads as a bound residue. Mn ions produced from the oxidative transformation of 1-NP by birnessite were also removed by sorption to Bir-AB. The Bir-AB was recovered quantitatively by simple filtration and was reused twice without significant loss of the initial reactivity.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.26 no.1
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• pp.261-274
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• 2000

The o/w emulsions were prepared with saccharide surfactants which were sucrose monostearate(S160), sucrose distearate(S110), and POE(20) methyl glucose stearate(SSE20). And for emulsion the oils used were n-hydocarbon, squalane(SQ), liquid paraffin(LP), octylpalmitate(OP), octylstearate(OS), alkyl benzoate(AB), isostearyl benzoate(ISB). The structures of o/w emulsion droplet were investigated by laser light scattering and the fractal dimensions were calculated from light intensity curves. Increasing of concentration, chain length, and nonpolarity of oils, fractal dimensions of emulsion droplets were found greater. In general fiactal dimensions were varied from 1.7 to 2.8 and its structures were fractal But the fractal dimensions of octadecane( $C_{18}$), 50, and LP emulsified with S110 and S160 were varied from 3.0 to 3.2 and its structures were more dense. The overall fractal dimensions of S110 and S160 were varied from 2.1 to 2.6, that of SSE20 were varied from 1.5 to 2.1. So it was found that the structures of SSE20 system were less compact than that of S110 and S 160 system, because the hindrance effect of polyoxyehtylene group of SSE20 was stronger than that of sucrose of S160. The strucures of emulsion droplets changed according to the nature of emulsifiers and to compositions of oil substances which they contained, and the structures were found similar when the hydophilic moiety of emulsifiers was same.

• Journal of Hydrogen and New Energy
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• v.7 no.2
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• pp.157-164
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• 1996

The AB5-type metal hydride electrodes using $(LM)Ni_{4.49}Co_{0.1}Mn_{0.205}Al_{0.205}$(LM : Lanthaniumrich Mischmetal) alloy powders(${\leq}200$mesh) which were coated with 25wt% copper in an acidic bath were prepared with or without addition of 10wt% PTFE as a binder. Prior to electrochemical measurements, the electrodes were sintered at $40^{\circ}C$ for 1 and 2hrs in vacuum with Mm(mischmetal) and sponge type Ti getters. The properties such as maximum capacity, cycle life and mechanical strength of the negative electrode have been investigated. The surface analysis of the electrode was also obtained before and after charge-discharge cycling using scanning electron microscope(SEM). From the observations of electrochemical behavior, it was found that the sintered electrode shows a lower maximum discharge capacity compared with non-sintered electrode but it shows a better cycle life. For the both electrodes with or without addition of PTFE binder, the values of mechanical strength were obtained, and their values increased with increasing sintering time. However, there is little difference of discharge capacity for both electrodes.

• Microbiology and Biotechnology Letters
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• v.4 no.3
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• pp.117-121
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• 1976

A microbial strain capable of degrading ABS (alkyl benzene sulfonate) was isolated and identified as Pseudomonas caryophylli. During the incubation of the isolated bacterium in a synthetic effluent containing 10 ppm of ABS, the extents of removal of ABS, BOD and COD were 40％, 89％ and 71％, respectively. The degradability of ABS by pure culture with the isolated strain was twice higher than that of mixed culture with natural microflora. The biodegradability of some commercial detergents in Korea by the isolated organism was as follows: Hiti 46.2％, Kleenup 37.5％, No.1 29％, and OK 27.9％.

• The Journal of the Petrological Society of Korea
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• v.4 no.1
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• pp.61-87
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• 1995

On the basis of lithology, the Precambrian Hongjesa Granitic Gneiss can be locally zoned into granoblastic granitic gneiss, porphyroblastic granitic gneiss, migmatitic gneiss from its center to the marginal part. There are no distinct differences in mineral assemblages by lithologic zoning, but it partly shows the change of mineral assemblage in the adjacent with migmatitic gneiss, thus mineral assemblage can be subdivided into Zone I and Zone II. In terms of mineral compositions, the characteristics of Zone I are coexisting K-feldspar+muscovite+sillimanite. The characteristics of Zone II are (1) breakdown of muscovite, (2) coexisting garnetScordierite, (3) coexisting garnet+cordierite + orthoamphibole. The Buncheon Granitic Gneiss is mainly composed of augen gneiss. In the adjacent area with Honjesa Granitic Gneisses, Buncheon Granitic Gneiss has the mineral assemblage of sillimanite+biotite+K-feldspar+(kyanite). Kyanite occurs as relict grains in the Buncheon and Hongjesa Granitic Gneissess. Kyanite shows anhedral to subhedral form and coexists with sillimanite in only one of these samples. Garnet from a migmatitic gneiss (Zone 11) has relatively high $X_{Fe}$ value in core and rim. Garnet from a porphyroblastic granitic gneiss(Zone I) has relatively homogemeous core but compositionally-zoned rim. Biotites show various colour from greenish-brown, brown to reddish brown at maximum adsorption. Also, the Ti, and Mg content in biotites increases from Zone I to Zone II. The plagioclases shows the chemical composition of $Ab_{84}An_{16}$ -$Ab_{70}An_{30}$ (oligoclase) in Zone I and $Ab_{70}An_{30}$ -$Ab_{50}An_{50}$(andesine) in Zone 11. These variations indicate that the gneisses in the study area experienced a upperamphibolite facies. The presence of kyanite as relict grains indicates that the metamorphic rocks in this area exprienced a high-temperature/medium-pressure type metamorphism, followed by high-temperaturellow-pressure metamorphism. Metamorphic P-T conditions for each gneiss estimated from various geothermobarometers and phase equilibria are 698-$729^{\circ}C$/6.3-11.3 kbar in augen gneiss, 621-$667^{\circ}C$/1.0-5.4 kbar in migmatitic gneiss, and 602-$624^{\circ}C$/1.9-3.4 kbar in porphyroblastic granitic gneiss. These data suggest that the study area was subjected to a clockwise P-T path with isothermal decompression (dP/dT=about 60 bar/$^{\circ}C$).

• Journal of Hydrogen and New Energy
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• v.10 no.4
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• pp.225-232
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• 1999

The $Mg_2Ni$ hydrogen storage alloys which have much higher theoretical discharge capacity than $AB_5$ and $AB_2$ type alloys were synthesized by mechanical alloying with some additives and subjected to the electrochemical measurements. Two different processes were employed to the synthesis of $Mg_2Ni$ alloys with using the high energy ball mill SPEX 8000. One was only ball milling, 12 hrs, the Mg and Ni powders for 12 hrs with additives such as $AB_5$, Ni, Co and Cu powders. In the other process the Mg and Ni powders were ball milled for 1 hr first and then heat treated at $300{\sim}400^{\circ}C$ for 1 hr to get $Mg_2Ni$ alloy, and finally the $Mg_2Ni$ alloy powders were ball milled with the additives for 12 hrs. The alloy powders prepared were compacted at room temperature under $7.64tons/cm^2$ into disk type electrodes for the electrochemical measurements. The experimntal results showed that the electrodes prepared with the heat treated alloy powders had a higher discharge capacities than those without heat treatment. The addition of Ni caused an increase of the discharge capacity and the addition of Co improved the cycling characteristics. The electrode prepared by ball milling of $Mg_2Ni$ and 10wt% Ni powders has showed the highest discharge capacity, 546mAh/g.alloy, which was 55% of the theoretical capacity.

• Korean Journal of Crystallography
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• v.4 no.1
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• pp.1-5
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• 1993

The crystal structure of N-(2'-chloro-4'-vitrophenyl)-5-chlorosalicylamide( Niclosamide ) monohydrate has been determined from 1976 sig- nificant independent reflections collected on an automated CAD4 diffractometer using graphitemonochromated Mo-Ka radiation. The crystal is monoclinic, space group P211c, with unit cell dimensions, a=11.331 (3), b=16.964(2), c=7.347(4)A , P =98.20(3)° and Z=4 at T=293k. The structure was solved by direct method using seminvariants of ggg Parity group and refined by the full-matrix least-square method, resulting model with reliability factor, R=0.046. The feature of the molecule show planar structure in parallel to the ab crystal plane.