• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.11 no.1
• /
• pp.88-94
• /
• 2012

An axle drive shaft with double joint shaft, cross kit and yoke has an important role by transferring power and changing steering angle between axle and wheel in power train system. It has been used widely in the heavy machinery requiring a high reliability in the power train system. At fatigue failures of the axle drive shaft with the long span, a relatively high stress concentration at a snap ring groove on the drive shaft brings to significant fatigue damages under repeated loading condition. As Peterson's suggestions on this study, a relief groove in the vicinity of the snap ring groove is applied by decreasing the stress concentration and improving the fatigue life of axle drive shaft. By using FEM analysis, the decreasing effect of the stress concentration and extended fatigue life are due to the change of design parameters related with size and location of the relief groove. The relief groove with the design parameters such as d/b=2.0 and r/h=1.2 enables to decrease the stress concentration of 22.3% and increase the fatigue life more than 3 times by comparing with no relief groove application.

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

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.14 no.8
• /
• pp.878-883
• /
• 2003

New feeding structures using linearly and exponentially tapered lines to planar microstrip resonators are proposed. These can overcome the design problems from coupling losses and impedance mismatching by increasing the coupling efficiency. The variation of its feeding angle is evaluated for the insertion loss and bandwidth and the feedline length is optimized at ${\lambda}_g$/2. The ring resonators and patches fed by the tapered line have been designed and implemented. The experimental results show that the insertion loss is enhanced by about 7 dB. Both rings and antennas are better matched, without disturbing the single-mode resonance or distorting their radiation pattern

• Computational Structural Engineering
• /
• v.7 no.2
• /
• pp.101-109
• /
• 1994

A degenerated cylindrical shell element for modeling glass fiber reinforced plastic pipes is developed and its performance for static structural analysis under internal uniform pressure is evaluated. The element is a nine node degenerated solid shell element with reduced integration technique, addition of nonconforming displacement modes, and assumed strain method to improve convergence of analysis. Several numerical examples are solved and compared with analytical solutions and other F.E.M programs, The results show that the increment of fiber orientation in the GFRP pipes with reference to the longitudinal axis cause less radial displacements and much stiffness in the pipes. This is reasonable since the internal pressure will primarily cause hoop stresses in the ring and 90-angle ply GFRP ring carry these efficiently in pure tension.

• The Bulletin of The Korean Astronomical Society
• /
• v.36 no.1
• /
• pp.62.1-62.1
• /
• 2011

Warp phenomenon seems to be ubiquitous among spiral galaxies, and a a number of mechanisms have been suggested as the origin including cosmic infall and tidal interactions. In this work, we compare warp characteristics of cluster spirals and the ones in the field in order to investigate the influence of environment on warping, in particular of gas disks. We make use of a tilted-ring modeling (TRM) method to VLA HI (21cm) data cubes of carefully selected 20 spiral galaxies in the Virgo cluster. The TRM allows us to probe kinematics, e.g., inclination, position angle, and velocity dispersion of HI disks. We compare the properties of each tilted-ring component to mean properties based on optical images. In this contribution, we present preliminary yet important findings on the warp characteristics of spiral galaxies in dense environment, and discuss possible origins of those kinematical structures.

• Bulletin of the Korean Chemical Society
• /
• v.10 no.4
• /
• pp.349-352
• /
• 1989

Two Crystal structures of fully dehydrated partially magnesium exchanged zeolite A, stoichiometries of $Mg_{2.5}Na_7-A$ (a = 12.251 (1) ${\AA}$) and $Mg_{1.5}Na_9-A\; (a\;=\;12.214(1)\;{\AA})$ per unit cell, have been determined from the 3-dimensional X-ray diffraction data gathered by counter methods. All structures were solved and refined in the cubic space group Pm3m at 21(1)$^{\circ}C$. The structures of the dehydrated $Mg_{2.5}Na_7-A$ and $Mg_{1.5}Na_9-A$ were refined to yield the final error indices $R_1$ = 0.042 and $R_2$ = 0.049 with 318 reflections, and $R_1$ = 0.034 and $R_2$ = 0.032 with 252 reflections, respectively, for which I > $3{\sigma}(I)$. Both structures indicate that $Mg^{2+}$ ions are coordinated by three framework oxygens and the angle substended at $Mg^{2+}$ ions, O(3)-Mg(1)-O(3) is ca. $120^{\circ}$, close to the idealized trigonal planar value. $Mg^{2+}$ ions preferentially occupy 6-ring sites and $Na^+$ ions occupy 8-ring sites when total number of cations per unit cell is more than 8.

• International Journal of Naval Architecture and Ocean Engineering
• /
• v.12 no.1
• /
• pp.501-517
• /
• 2020

Three-dimensional numerical simulations were performed to study the effects of flow direction and flow velocity on the flow regime behind a curved pipe represented by a curved circular cylinder. The cylinder is based on a previous study and consists of a quarter segment of a ring and a horizontal part at the end of the ring. The cylinder was rotated in the computational domain to examine five incident flow angles of 0-180° with 45° intervals at Reynolds numbers of 100 and 500. The detailed wake topologies represented by λ2 criterion were captured using a Large Eddy Simulation (LES). The curved cylinder leads to different flow regimes along the span, which shows the three-dimensionality of the wake field. At a Reynolds number of 100, the shedding was suppressed after flow angle of 135°, and oblique flow was observed at 90°. At a Reynolds number of 500, vortex dislocation was detected at 90° and 135°. These observations are in good agreement with the three-dimensionality of the wake field that arose due to the curved shape.

• Bulletin of the Korean Chemical Society
• /
• v.30 no.8
• /
• pp.1755-1759
• /
• 2009

Surface structure and molecular orientation of self-assembled monolayers (SAMs) formed by the spontaneous adsorption of tetrahydrothiophene (THT) and thiophene (TP) on Au(111) were investigated by means of scanning tunneling microscopy (STM) and carbon K-edge near edge X-ray absorption fine structure (NEXAFS) spectroscopy. STM imaging revealed that THT SAMs have a commensurate (3 ${\times}\;2\sqrt[]{3}$) structure containing structural defects in ordered domains, whereas TP SAMs are composed of randomly adsorbed domains and paired molecular row domains that can be described as an incommensurate packing structure. The NEXAFS spectroscopy study showed that the average tilt angle of the aliphatic THT ring and $\pi$-conjugated TP ring in the SAMs were calculated to be about $30^o\;and\;40^o$, respectively, from the surface normal. It was also observed that the $\pi$* transition peak in the NEXAFS spectrum of the TP SAMs is very weak, suggesting that a strong interaction between $\pi$-electrons and the Au surface arises during the self-assembly of TP molecules. In this study, we have clearly demonstrated that the surface structure and adsorption orientation of organic SAMs on Au(111) are strongly influenced by whether the cyclic ring is saturated or unsaturated.

• The Bulletin of The Korean Astronomical Society
• /
• v.37 no.2
• /
• pp.117.1-117.1
• /
• 2012

Energetic neutral atoms (ENAs) are emitted by charge exchange collisions between energetic ions and cold neutral atoms. ENAs can be used as an alternative measure of the energetic ions in the source region because they maintain the energy and pitch angle of the source energetic ions. In the present study we present simulation results of the ENA emissions during a magnetic storm to be measured by the STEIN instrument onboard the CINEMA/TRIO satellites. The CINEMA/TRIO mission consists of three identical cubesats with low-altitude orbits. The STEIN instrument onboard each cubesat can measure ENAs with energies from ~4 keV to ~20 keV as well as suprathermal electrons and ions. The measurement of ENA emissions from ring current by STEIN is simulated using the models for energetic ring current ions and geocoronal neutral atoms. Especially we will discuss about the energy spectrum of the ENAs and the effect of transient variations of the ring current.

• Bulletin of the Korean Chemical Society
• /
• v.18 no.1
• /
• pp.14-18
• /
• 1997

Sulconazole nitrate, C18H16Cl3N3O3S, crystallizes in monoclinic, space group C2/c, with a=14.401(1), b=8.051(1), c=34.861(2) Å, β=95.9(1)°, g=0.58 mm-1, Dc=1.523 g/cm3, Dm=1.522 g/cm3, F(000)=1888.0, and z=8. Intensities for 2460 unique reflections were measured on a CAD4 diffractometer with graphited-monochromated Mo-Kα radiation. The structure was solved by direct method and refined by full matrix least squares to a final R=0.071 for 2182 reflections (Io > 2σIo). The bond lengths and angles are comparable with the values found in the analogues imidazole derivatives. The 2,4-dichlorophenyl ring(A) and the p-chlorophenyl ring(B) are almost planar with different heights [dihedral angle 17.3°] while the imidazole ring(C) is nearly perpendicular to the two phenyl rings[dihedral angles about the two rings A, B are 110.8° and 96.1° respectively]. In order to understand the overall conformation we calculated the selected distances (l1, l2, l3) among the center of the three rings and considered the imaginary plan D[C(7), C(9) and C(16)]. The two polar group S(8) and N(19) do not have gauche conformation and l2 value (4.47 Å) is shorter than the other imidazole derivatives. One -NO3 group are hydrogen bonded the two neighbored sulconazole molecules. The molecular crystal packing is also formed by two hydrogen bondings and van der Waals forces.