• BMB Reports
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• v.32 no.4
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• pp.363-369
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• 1999

The orf8(chlD) gene cloned from Streptomyces antibioticus T$\"{u}$99 was overexpressed using an E. coli system to confirm its biological function. Induction of the E. coli strain transformed with recombinant plasmid pRFJ 1031 containing orf8 resulted in the production of a 43,000 dalton protein. Glucose-1-phosphate thymidylyltransferase activity of the cell extract obtained from the transformed strain was 4-5 times higher than that of the control strain. The expressed protein was purified 18-fold from E. coli cell lysate using three chromatographic steps with a 17% overall recovery to near homogeneity. The N-terminal amino acid sequence of the purified protein agrees with the nucleotide sequence predicted from the orf8 gene. The SDS-PAGE estimated subunit mass of 43,000 dalton agrees well with that calculated from the amino acid composition deduced from the nucleotide sequence of the orf8 gene (43,000 Da). Also, the native enzyme has a monomeric structure with a molecular mass of 43,000 dalton. The purified protein showed glucose-1-phosphate thymidylyltransferase activity catalyzing a reversible bimolecular group transfer reaction, and was highly specific for dTTP and ${\alpha}$-D-glucose 1-phosphate as substrates in the forward reaction, and for dTDP-D-glucose and pyrophosphate in the reverse reaction.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.52 no.1
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• pp.28-34
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• 2003

In this paper, a predistortion linearizer using series diode is proposed for linearizing the power amplifier in microwave radio systems. The power amplifier should be operated near saturation region to achieve high efficiency. But at this region, amplitude and phase distortions of the amplifier remarkably increase with the increase of input power and cause a significant adjacent channel interference. The linearizer is composed of a series diode with a parallel capacitor, which provides positive amplitude and negative phase deviations with the increasing input power. This type of linearizer using the nonlinearity of diode has improved the C/I(Carrier to Intermodulation Distortion) ratio well. By applying this linearizer to two-tone 880MHz power amplifier, adjacent channel leakage power is improved up to 5dBm.

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.17 no.4
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• pp.426-434
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• 1988

Series expansion is applied to solve the laminar boundary layer equations for the problem of natural convection from vertical cylinder with uniform surface heat flux. The series in terms of transverse curvature parameter ${\xi}$ is extended to five terms and is well converged by applying the Shanks transform twice. In case of natural convection from a vertical cylinder heated with uniform surface heat flux, it is possible to consider the vertical cylinder as vertical plate under the condition of D/L${\geq}$A/$(Gr_L^*)^{1/5}$, where A is in the range of 5.7~55.2. Also, mean Nusselt number ${\overline{Nu_L}}$ can be represented as $C_1(Ra_L^*)^{1/5}$, where $C_1$ is a constant which depends on Pr and is in the range of 0.5~0.8.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1999.10a
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• pp.257-266
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• 1999

This paper presents a method of seismic analysis for a cylindrical liquid storage structure on/in horizontally layered half.space considering the effects of the interior fluid and exterior soil medium in the frequency domain. To capture the essence of fluid-structure-soil interaction effects effectively, a mixed finite element with two-field (u, p) approximation is employed to model the compressive inviscid fluid, while the structure and soil medium are presented by the 3-D axisymmetric finite elements and dynamic infinite elements. The present FE-based method can be applied to the system with complex geometry of fluid region as well as with inhomogeneous near-field soil medium, since it can directly model both the fluid and the soil. For the purpose of verification, dominant peak frequencies in transfer functions for horizontal motions of cylindrical fluid storage tanks with rigid massless foundation on a homogeneous viscoelastic half.space are compared with those by two different added mass approaches for the fluid motion. The comparison indicates that the Present FE-based methodology gives accurate solution for the fluid-structure-soil interaction problem. Finally, as a demonstration of versatility of the present study, a seismic analysis for a real-scale LNG storage tank embedded in layered half.space is carried out, and its member forces along the height of the structure are compared with those by an added mass approach developed by the present writers.

• Journal of The Korean Astronomical Society
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• v.10 no.1
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• pp.23-30
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• 1977

We have collected times of minimum light available in the literature for WZ Andromedae and analyzed the nature of the period variations. The O-C diagram of WZ And clearly shows that two abrupt changes near JD 2418000 and JD 2435000 are deduced by dp/p=$+4.24{\timesa}10^{-6}$ and dp/p=$-2.46{\times}10^{-6}$, respectively. For these period changes, we have introduced the equations which represent mass exchange in the close binery systems given by Biermann and Hall (1973), and the computation yieleled a mass flow of $7.42{\times}10^{-5}M$. from the hotter component to the cooler one. Due to the amount of mass flow, the period decrease may also be calculated. The theoritical new period after JD 2435000 became 0.69565858 days, which is in good agreement with the value 0.69566034 days found in the O-C diagram. In this computation, the mass ratio of WZ And suggested that the hotter star is the filling its Rochclooe, and thus WZ And is in Paczynski's stage II.

• The Bulletin of The Korean Astronomical Society
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• v.44 no.1
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• pp.80.1-80.1
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• 2019

Photometric investigations of asteroids allow us to determine their rotation states and shape models (Apostolovska et al. 2014). Our main target, asteroid (2078) Nanking's perihelion distance (q) is 1.480 AU, which belongs to the Mars-crossing asteroid (1.3 < q < 1.66 AU). Mars-crossing asteroids are objects that cross the orbit of Mars and regarded as one of the primary sources of near-Earth asteroids due to the unstable nature of their orbits. We present the analysis of the spin parameters and 3D shape model of (2078) Nanking. We conducted Cousins_R-band time-series photometry of this asteroid from November 26, 2014 to January 17, 2015 at the Sobaeksan Optical Astronomy Observatory (SOAO) and for 25 nights from March to April 2016 using the Korea Microlensing Telescope Network (KMTNet) to reconstruct its physical model with our dense photometric datasets. Using the lightcurve inversion method (Kaasalainen & Torppa 2001; Kaasalainen et al. 2001), we determine the pole orientation and shape model of this object based on our lightcurves along with the archival data obtained from the literatures. We derived rotational period of 6.461 h, the preliminary ecliptic longitude (${\lambda}_p$) and latitude (${\beta}_p$) of its pole as ${\lambda}_p{\sim}8^{\circ}$ and ${\beta}_p{\sim}-52^{\circ}$ which indicates a retrograde rotation of the body. From the apparent W UMa-shaped lightcurve and its location in the rotation frequency-amplitude plot of Sheppard and Jewitt (2004), we suspect the contact binary nature of the body (Choi 2016).

• Journal of the Korean Society of Food Science and Nutrition
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• v.21 no.2
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• pp.163-170
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• 1992

Color of kimchi juice was measured instrumentally to evaluate the quality of Korean cabbage kimchi during fermentation at 4$^{\circ}C$ and 16$^{\circ}C$ . These results were compared with those of chemical analyses of kimchi juice and sensory evaluation for kimchi. Chemiral analyses and sensory evaluation showed that the kimchi has reached pH 4.3, the pH value under an optimum ripening period, after 3-days fermentation at 16$^{\circ}C$ with almost the highest contents of vitamin C and carotenoids as well as desirable sour taste and texture. At 4$^{\circ}C$ the kimchi was unripened after 6-days fermentation. At 16$^{\circ}C$, $L^{*}$ value of kimchi juice did not show any significant change during fermentation periods. However, $a^{*}$ value increased until day 4$^{\circ}C$ and thereafter decreased sharply. $b^{*}$ value increased until day 3 and then showed no change. High correlations were seen between volume of kimchi juice, pH, total acidity and $L^{*}$or $b^{*}$ value, and between carotenoid content and $a^{*}$ value, respectively. It was desirable to use color $a^{*}$ or $b^{*}$ value of kimchi juice to evaluate the quality of kimchi. The kimchi was under an over-ripening period when $a^{*}$ value was equal to or lower than the initial value, or when $b^{*}$ value was almost constant. Predicting an optimum ripening period was possible by using a proportional value of $a^{*/}$ $b^{*}$ , i.e., unripening period, 1 $\geq$ and near 1 ; optimum ripening period, near 0.8 ; over-ripening period, < 0.8.eriod, < 0.8.d, < 0.8.

• Journal of Korean Ophthalmic Optics Society
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• v.15 no.1
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• pp.99-104
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• 2010

Purpose: Difference of refraction result from the method of autorefraction and iTrace were investigaged for the children of elementary school in Asan City. In iTrace method. exclusion of accommodation without cycloplegia was used. Methods: Manifest refractive stale of 42 eyes of 12~13 years old were measured using autorefractor and iTrace. Refractions of far (more than 5 m) and ncar (30 cm) vision were measured using iTrace. All data showed that the spherical equivalent were classified as being in the group 1 (-0.50D < ~ < +1.00D) and 2 (below -0.50D) according 10 refractive errors. Results: Mean spherical equivalent using autorefractor and iTrace (far and near vision) were -1.08D, -0.29D and -2.34D, respectively (p<0.01). Compared with the far vision using iTrace, autorefraction was measured the myopia with -0.50D ~ -1.00D in 52.4% of total eyes. Autorefraction also statistical significant were measured a more myopia than the far vision using iTrace in group I and 2. Conclusions: The difference of refractive errors between autorefraction and iTrace, objective refraction were measured with far vision of more than 5 m were -0.79D. Autoreftaction showed statistically decreased refraction errors than iTrace with far vision.

• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.8
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• pp.1493-1502
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• 1992

The purpose of this study is to identify the effects of loading variables on fatigue crack opening behavior, using structural steel SS41. To use various stress ratios, three kinds of the methods varying stress ratio were used; .DELTA.P const., P$_{max}$ const., and P$_{min}$ const.. To measure the opening load, the direct measuring method which measures the distance between two micro indentations 20 .mu.m behind crack tip and the elastic compliance method were used. As the results of present study, the following conclusions are obtained. First, using the direct measuring method, it was possible to measure the COD at any location behind crack tip. Second, as measuring point becomes farther from crack tip, opening load becomes smaller. Third, the acceleration of da/dN near notch is due to crack opening behavior. Finally, opening ratio is a function of not only R, but .DELTA.K.K.K.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2008.10a
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• pp.174-177
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• 2008

This paper replaces an conventional 300-austenitic stainless steel sheet to a 400-ferritic stainless steel for the cost reduction of a pulsator cover of a washing machine. However, ferritic stainless steel has poor formability in comparison with austenitic one. The low formability of ferritic steel results in problems during stamping such as fracture, wrinkling, shape inaccuracy and so on. Design modification of the stamping tool is carried out with the aid of the finite element analysis for multi-stage stamping process. The simulation results show that fracture occurs on top of the product while wrinkles are generated by the excess metal near the wing part. Modification of the initial stamping die is performed to improve metal flow and to eliminate problems during the stamping process. Simulation with the modified design fully demonstrates that safe forming is possible without inferiorities.