• 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 Korean Society of Steel Construction
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• v.8 no.3 s.28
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• pp.35-45
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• 1996

The purpose of this paper is to investigate experimentally the strength and deformation of T-joints to improve the structural behavior of truss connection consisted in square hollow steel section. There are two-types to be changed in T-joint shape. One type is TP-series that a brace member is rotated to 45 degree, another type is TR-series that a chord member is rotated to 45 degree. The most important results obtained from the 2nd experiment on the T-joints is as follow; The yielding strength and initial stiffness of TP-series increase more than a current type(TS-series) in $0.6{\leq}{\beta}(d/D){\leq}0.7(0.85{\leq}{\beta}$'$(={\sqrt2}{\cdot}{\beta}){\leq}1.0)$.

• Journal of the Korean Ceramic Society
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• v.32 no.7
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• pp.858-864
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• 1995

A porous glass-ceramics body was prepared in the phosphate system. The glass composition of 47.2CaO-22.2TiO2-30.6P2O5 (mol%) containing a few weight percent of ZrO2 was suitable for a mother glass of a porous glass-ceramics. The dense glass-ceramics body was made by a two-step heat treatment of the mother glass. The crystalline phases of the glass-ceramics were $\beta$-Ca3(PO4)2 and CaTi4(PO4)6. The $\beta$-Ca3(PO4)2 phase could be selectively leached out with HCl solution and thus a crystalline $\beta$-Ca3(PO4)2 skeleton was remained. The dimension and shape of the porous glass-ceramics were nearly the same as the those of the first formed glass. The specific surface area and average proe radius of the porous glass-ceramics were 19$m^2$/g and 22 nm, respectively.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.4 no.1
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• pp.63-70
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• 1994

Single crystals of the superionic conductor ${\beta}-Ag_3SI$ were prepared by thermal treatmentr from the reactant mixture of AgI and $Ag_2S$. The growing single crystals were made to spherical shape of $200{mu}m$ in diameter. The detailed structures analyses revealed that $Ag^+$ in ${\beta}-Ag_3SI$ distribute on 12h site of 4-coordination inpreference to 3c site of 6-coordination. The effective one-particle potential (o.p.p.). of $Ag^+$ along [110] direction was evaluated from the probability density function(p.d.f.) Activation energy calculated from the o.p.p. curve has been found to be 0.012 eV for the diffusion of $Ag^+$ on (001) plane in the ${\beta}-Ag_3SI$ structure.

• Bulletin of the Korean Chemical Society
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• v.29 no.5
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• pp.953-958
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• 2008

A novel anthraquinone diamino-bridged bis($\beta$ -cyclodextrin) 2 was synthesized. The inclusion complexation behaviors of the native $\beta$ -cyclodextrin 1 and the novel bis($\beta$ -cyclodextrin) 2 with guests, such as acridine red (AR), neutral red (NR), ammonium 8-anilino-1-naphthalenesulfonate (ANS), sodium 2-(p-toluidinyl) naphthalenesulfonate (TNS) and rhodamine B (RhB) were investigation by fluorescence, circular dichroism and 2D NMR spectroscopy. The spectral titrations were performed in phosphate buffer (pH 7.20) at 25 ${^{\circ}C}$ to give the complex stability constants (Ks) and Gibbs free energy changes (−${\Delta}G^0$) for the stoichiometric 1:1 inclusion complexation of host 1 and 2 with guests. The results indicated that the novel bis($\beta$ -cyclodextrin) 2 greatly enhanced the original binding affinity of the native $\beta$ -cyclodextrin 1. Typically, bis($\beta$ -cyclodextrin) 2 showed the highest binding constant towards ANS up to 34.8 times higher than that of 1. The 2D NMR spectra of bis($\beta$ -cyclodextrin) 2 with RhB and TNS were performed to confirm the binding mode. The increased binding affinity and molecular selectivity of guests by bis($\beta$ -cyclodextrin) 2 were discussed from the viewpoint of the size/shape-fit concept and multipoint recognition mechanism.

• YAKHAK HOEJI
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• v.29 no.2
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• pp.62-69
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• 1985

The isomeric intermediates, $3{\alpha}$and $3{\beta}-amino-5{\alpha}-cholestane required for the synthesis of N-nitrosoureas, N-(2-chloroethyl)-N-nitrosocarbamoyl-$3{\alpha}-amino-5{\alpha}$-cholestane (9), N-methyl-N-nitrosocarbamoyl-3${\alpha}-amino-5{\alpha}-cholestane$ (10), N-(2-chloroethyl)-N-nitrosocarbamoyl-$3{\beta}-amino-5{\alpha}-cholestane$: (7), and N-methyl-N-nitrosocarbamoyl-$3{\beta}-amino-5{\alpha}-cholestane$ (8) were obtained through the $LiAlH_{4}$ reduction of $5{\alpha}$-cholestan-3-one oxime, followed by the chromatographic separation: the assignment of the stereochemistry of both isomers were based on the shape and chemical shift of $C_{3}$-proton resonances on their NMR spectra and on the elution mobility on the TLC. The urea intermediates, N-(2-chloroethyl) carbamoyl-3.alpha.-amino-5.alpha.-cholestane (13), N-methylcarbamoyl-$3{\alpha}-amino-5{\alpha}-cholestane$ (14), N-(2-chloroethyl) carbamoyl-$3{\beta}-amino-5{\alpha}-cholestane (11) and N-methyl-$3{\beta}-amino-5{\alpha}$-cholestane (12) were prepared by the treatment of each isomers ($3{\alpha}$-amino-and $3{\beta}-amino-5{\alpha}$-cholestane) with alkyl isocyanates in anhydrous $CHCl_{3}$, and the corresponding nitrosoureas, 7-10 were obtained by the nitrosation of the ureas, 11-14, with AcOH (or HCOOH)/$NaNO_{2}$ in ice-cold condition. The inhibitory activity of the nitrosoureas, 7-10, and their intermediates, 12-14 towards the growth of L1210 murine leukemia cells, were examined. Among them, the compounds 9 and 10 exhibited high activity having $ED_{50}$ to be 5.5g/ml and 6.1g/ml, respectively.

• Proceedings of the Materials Research Society of Korea Conference
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• 2011.05a
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• pp.40.2-40.2
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• 2011

As the old saying 'nothing is complete unless you put it in final shape', although nanosheets (NSs) are a promising functional building block for various electrochemical applications, their true value cannot be realized until they are well woven into electrical conducting materials. As an effort to determine their ideal shape, in this study, a unique manufacturing route to build a layer-by-layer (LBL) structure of two-dimensionally ordered, free-standing ${\beta}$-nickel hydroxide nanosheets (${\beta}$-NHNSs) that are fully electrically addressed with single-wall carbon nanotube fabrics was demonstrated, and its capabilities were verified through a comparative study on the differences between a simple bulky and LBL-structured electrochemical cathode, representing two extreme cases. The LBL-structured cathode showed a discharging current peak that was 25 times larger than the bulky structured one measured in cyclic voltammetry, which implies that the LBL structure is near an ideal electrode configuration for NS-based electrochemical applications.

• Wind and Structures
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• v.29 no.4
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• pp.225-234
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• 2019

Conductor galloping is a common disaster for the transmission lines. Among the existing analytical methods, the wind tunnel test is highlighted as the most effective approach to obtain the aerodynamic coefficients. In this paper, the aerodynamic coefficients of 12 conductor models covered with the crescent-shaped ice, which were fabricated considering the surface roughness of the iced conductor, were obtained based on the wind tunnel test. The influence of the Reynolds number and the shape parameter ${\beta}$, defined as the ratio of ice thickness to the diameter, were investigated. In addition, the effect of surface roughness of the iced conductor was discussed. Subsequently, unsteady areas of conductor galloping were calculated according to the Den Hartog criterion and the Nigol criterion. The results indicate that the aerodynamic coefficients of iced conductors change sharply at the attack angles of $20^{\circ}$ and $170^{\circ}$ with the increase of ${\beta}$. The surface roughness of iced conductors changed the range of attack angle, which was influenced by the increase of the Reynolds number. The experimental results can provide insights for preventing and controlling galloping.

• Journal of Powder Materials
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• v.6 no.4
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• pp.307-313
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• 1999

The effect of carbon content on the shape of WC grains dispersed in the Co-rich matrix during liquid phase sintering of WC-35%Co hard metals has been determined. The shape of WC grains was observed using SEM stereography after removing cobalt matrix with boiling hydrochloric acid solution. The WC grains changed from hexagonal to trigonal prism as the carbon content increased in the two-phase region of(WC + $\beta$ - Co), while the morphology of WC grains changed from trigonal to hexagonal shape as the carbon content decreased. The morphology of WC grains changes reversibly along with carbon loss or carbon pick-up. Morphology change of WC grains is attributed to crystal structure of WC, which has an asymmetric array of carbon atoms. There are two types of prismatic planes having different numbers of broken W-C bonds in WC grains. It is scrutinized that as the carbon content increases, the high energy prism planes grow fast and the crystals change from hexagonal to trigonal shape. On the other hand, when the carbon content decreases, the high energy prism planes are dissolved accompanying split of (100) plane into (101) and (101) planes.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.18 no.11
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• pp.76-82
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• 2019

This study aims to find the shapes of an end-mill with low cutting temperature during the end-mill process of Ti-6Al-4V alloy. Such ${\alpha}-{\beta}$ titanium alloys are increasingly more used for their high tensile strength and high corrosion resistance. The cutting characteristics of Ti-6Al-4V alloy were studied using an analytical method validated by comparing the estimated cutting resistance with that from experiments. The end-mill shape was analyzed using an experimental method. The end-mill shape with low cutting resistance and low cutting temperature was confirmed by analyzing the signal-to-noise ratios for various conditions. Then, the factors with significance factor of 95% or more were determined in the variance analysis. Finally, an end-mill shape that can ensure a low cutting temperature was proposed.