• Journal of Microbiology and Biotechnology
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• v.4 no.3
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• pp.204-209
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• 1994

The synthesis of N-(benzyloxycarbonyl)-L-aspartyl-L-phenylalanine methylester (Z-APM), a precursor of aspartame, from N-(benzyloxycarbonyl)-L-aspartic acid (Z-Asp) and L-phenylalanine methylester hydrochlolide($L-PM\cdot HCI$) was investigated in a saturated-ethylacetate single phase system using immobilized thermolysin. Among the various supports tested, glyceryl-CPG was found to be most efficient for retaining enzyme activity. The enzyme immobilized onto glyceryl-CPG also showed the highest activity for Z-APM synthesis in saturated ethyl acetate. Z-APM conversion yield in saturated ethylacetate was half of that obtained in an ethyl acetate-buffer two-phase system under the same reaction conditions. However, as the mole ratio of $L-PM \cdot HCI$ to Z-Asp was increased to 4.0, the conversion yield reached 95 %. When continuous synthesis of Z-APM was canied out in a plug flow reactor (PFR) with 80 mM of L-PMㆍHCI and 20 mM of Z-Asp in saturated ethylacetate (pH 5.5), more than 95 % of Z-Asp was converted to Z-APM with a space velocity of 1.16 $hr^{-1} at 40^{\circ}C$. Although the operational stability in PFR was reduced rapidly, more than 80% of initial activity was maintained in CSTR even after a week of operation.

• Journal of Microbiology and Biotechnology
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• v.16 no.1
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• pp.57-63
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• 2006

We have cloned a xylanase gene (xynA) from Streptomyces thermocyaneoviolaceus. The deduced amino acid sequences of the XynA, including the active site sequences of glycosyl hydrolase family 10, showed high sequence homology with several xylanases assigned in this category. The XynA was overexpressed under an IPTG inducible T7 promoter control in E. coli BLR(DE3). The overproduced enzymes were excreted into culture supernatants and periplasmic space. The purified XynA had an apparent molecular mass of near 54 kDa, which corresponds to the molecular mass calculated from its gene. The optimum pH and temperature of the purified XynA were determined to be 5.0 and $65^{\circ}C$, respectively. The XynA retained over $90\%$ its activity after the heat treatment at $65^{\circ}C$ for 30 min. The XynA was highly efficient in producing xylose (X1), xylobiose (X2), xylotriose (X3), and xylotetraose (X4) from xylan.

• Journal of Electrical Engineering and Technology
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• v.3 no.1
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• pp.43-51
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• 2008

Evolutionary Algorithms (EAs) cover all the applications involving the use of Evolutionary Computation in electronic system design. It is largely applied to complex optimization problems. EAs introduce a new idea for automatic design of electronic systems; instead of imagine model, ions, and conventional techniques, it uses search algorithm to design a circuit. In this paper, a method for automatic optimization of the digital circuit design method has been introduced. This method is based on randomized search techniques mimicking natural genetic evolution. The proposed method is an iterative procedure that consists of a constant-size population of individuals, each one encoding a possible solution in a given problem space. The structure of the circuit is encoded into a one-dimensional genotype as represented by a finite string of bits. A number of bit strings is used to represent the wires connection between the level and 7 types of possible logic gates; XOR, XNOR, NAND, NOR, AND, OR, NOT 1, and NOT 2. The structure of gates are arranged in an $m{\times}n$ matrix form in which m is the number of input variables.

• Archives of Pharmacal Research
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• v.14 no.2
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• pp.137-142
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• 1991

The structure of a $\beta$-allyl type phenylpropanoid was determined by single crystal X-ray diffraction analysis. The compound was recrystallized from a mixture of n-hexane and benzene in monoclinic crystal system with a = 24.782 (2), b = 10.537 (1), c = 7.871 (1) ${\AA}, \beta=95.74$ (1)$^\circ, $D_x$=1.216, $D_m$=1.22g/$cm^3$, space group $P2_1/a$, and Z=4. The structure was solved by direct method and refined by least-squares procedure to the final R value of 0.054 for 2824 observed reflections {$F{\geq}3\sigma(F)$}. The molecular geometry shows a most stable trans-form with respect to the bulky phenyls, and this conformation is settled by an intramolecular hydrogen bond. In the crystal, the molecules are arranged along with the screw axis, and stabilized by the $O{\cdot}H{\cdots}O$ type intermolecular hydrogen bonds. The other intermolecular contacts appear to be the normal van der Waals' interactions. The compound is a dimeric phenylpropanoid, and belongs to the neolignan analogues.

• Journal of the Korean Vacuum Society
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• v.8 no.4A
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• pp.482-489
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• 1999

AC PDP(P1asma Display Pane1)s use the mixture of inert gases to generate a discharge inside the display pixels. Impurities such as CO, $CO_2$ and OH inside discharge region may deteriorate the characteristics of PDP operation during long life time of PDP. Electro-negative gas such as CO can cause the sustain pulse amplitude to rise by attaching electrons which will play an important role in the earlier stage of the discharge. MgO film is used to protect the dielectric layer in AC PDP, and is in contact with the free space of display pixel where it is filled with the inert gas mixture. So, MgO film can be a main source of impurities. In this experiment, we observed the change of impurity generation of various MgO films which were deposited by different methods, by using QMS. (quadropole mass spectrometer) The main impurites were $H_2$, CO and $CO_2$. And with the comparison of the TPD (temperature programmed desorption) result, it can be understood that impurity gases are generated by sputtering of MgO surface not by outgassing. Deposition method had effects on the characteristics of the impurity generation. The MgO film manufactured by e-beam evaporation generated more amount of impurity gases than the MgO films manufactured by sputtering or ion-plating. And also heat treatment of MgO film after deposition decreased the magnitude of impurity gas generation.

• Bulletin of the Korean Chemical Society
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• v.26 no.4
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• pp.594-598
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• 2005

Treatment of a solution of $CuCl_2$ in dimethyl phosphate (DMP) with DMSO under nitrogen atmosphere afforded to a light blue fluorescence powder. Slow evaporation of $H_2O$-DMSO solution of this powder resulted in blue-sky crystals of a new polymeric Cu(II) complex, with a unit cell composed of $Cu_2(DMP)_4$(DMSO), (1). The crystal and molecular structure of the complex acquired crystallographically. Compound (1) crystallizes in the monoclinic space group $P2_1$/n with a = 12.8920(11) $\AA$, b = 13.1966(11) $\AA$, c = 14.7926(13) $\AA$, $\alpha$ = 90$^{\circ}$, $\beta$ = 98.943(2)$^{\circ}$, $\gamma$ = 90$^{\circ}$, V= 2486.1(4) ${\AA}^3$, and Z = 4. A square pyramidal environment for the metal center was established by coordination of oxygen atoms of four bridging DMP ligands in the basal positions and binding a tri-centered oxygen atom of DMSO in the apical disposition of Cu(II). The sixth position was also affected by a weak interaction with the sulfur atom of another DMSO. The phosphorous atom in the bridging DMP was arranged in a deformed tetrahedron with (gg) conformation for methyl esters with $C_{2v}$ symmetry.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.03a
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• pp.1061-1064
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• 2008

A completion of settling process takes a lot of time for dredged materials of high moisture content, such as contaminated sludge, in landfill site. In general, additives (e.g. flocculants) are used for reducing settling time of such colloidal material, which results in the increase of sludge volume, and hence much space is required in landfill site. This study is to suggest alternative method in order to enhance the settling process of cohesive clayey soils. A number of gravitational sedimentation tests as well as electrokinetic experiments were conducted to investigate the variation of initial moisture content on the settling behaviour of clay slurry. Surface settlement, electric current and local voltage gradient were monitored during the experiment, and moisture content and soil pH were measured after the experiment. From the results, the application of electrokinetics was found to be effective in volume reduction (i.e. increase of settling velocity and decrease of final moisture content) by comparison with gravitational settling process.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.1
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• pp.61.1-61.1
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• 2012

We examine both optical and optical/near-infrared (NIR) color distributions of the globular cluster (GC) system in the core of the Coma cluster of galaxies (Abell 1656), centered on the giant elliptical galaxy NGC 4874, to study how non-linearities in the color-metallicity relations of GC systems in large elliptical galaxies are linked to bimodal optical color distributions. Since optical-NIR color distributions of extragalactic GC systems reflect the underlying features of the metallicity distributions, we also present the color-color relation for this GC system. In order to do this, we combine F160W ($H_{160}$) NIR imaging data acquired with the Wide Field Camera 3 IR Channel (WFC3/IR), newly installed on Hubble Space Telescope (HST), with F475W ($g_{475}$) and FF814W ($I_{814}$) optical imaging data from the HST Advanced Camera for Surveys (ACS). To quantitatively explain the feature of color distributions, we use the Gaussian Mixture Modeling (GMM) code. Finally, we show the radial distribution of the GCs in the field of NGC 4874.

• Journal of the Korean Chemical Society
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• v.6 no.2
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• pp.117-121
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• 1962

The waters throughout Taegu area for 87 points were analysed and according to the analytical data, following unfavorable characteristics for industrial uses were given: (1)Shows strong hardness, (2)Has high ratio of ignition residue to evaporation residue, (3) pH value is over 7, (4) Contains considerable quntities of iron.And then investigated the exchange rate and regeneration level of iron ion using cation exchange resin, Lewatit KS.When the hard water containing 2.2 ppm of iron with 18.4 ppm of calcium and 6.2 ppm of magnesium was passed through the ion exchange resin under $3cc/cm^2/min$ in exhaustant flow rate, exchange rate of iron reached to 42% after 300 hours flow. The exchange efficiency shows abrupt decreasing in initial stage of flow up to 100 hours flow. The exchanger which contains iron was regenerated with 10% sodium hydroxide aqua solution under SV (space velocity) 4. By this method, 57% of iron was eliminated from exchanger while calcium and magnesium are removed as much as 85% and 87% respectively.

• Bulletin of the Korean Chemical Society
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• v.23 no.11
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• pp.1527-1530
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• 2002

1,12-diazacyclodocosane-2,11-dione was first isolated from a plant Phyllanthus niruri Linn. Its structure has been determined by means of spectroscopy methods and X-ray crystallography. Two peptide groups in the big ring (lactam) are the main factors influencing intermolecular contacts. The hydrogen-bond interaction of these hydrophilic groups is observed in the crystal structure. Meanwhile, C-H···O hydrogen bonds in molecules contribute to the formation of the whole crystal. These two kinds of hydrogen-bond form six- member rings among molecules. This compound crystallizes in the triclinic space group P-1 with a= 9.588(1) $\AA$, b= $9.850(1)\AA$, c = $11.810(1)\AA$, $\alpha=$ 68.18(1)$^{\circ}C$ , $\beta=$ 84.98(1), $\gamma$ = 86.03(1)$^{\circ}C$ , V = $1030.66(17)\AA3$ , Z = 2. A disorder of five-member carbon chain in the whole ring is observed in the title compound. The bond angle 105.8(4) is determined for a extreme configuration C(14)-C(15)-C(16), and 117.7(10) for another extreme configuration C(14')-C(15')-C(16'). In this crystal, two molecules are tied each other by short intermolecular hydrogen bonds, the oxygen atom being tied by hydrogen bond to nitrogen atom of another two molecules. The NMR and IR spectral data coincides to the structure of the compound.