We present a method to improve the RV (radial velocity) measurements accuracy by using telluric lines. Telluric lines are used to estimate the wavelength scale drift over the detector of the spectrograph. In the case of BOES, the Echelle spectrograph at BOAO (Bohyunsan Optical Astronomical Observatory), the wavelength scale drift can be several hundreds m/s over 24 hours. Due to the wavelength scale drift, the RV measurements accuracy of BOES is limited to several hundreds m/s. By estimating the wavelength scale drift by telluric lines, we can remove its effect to improve the RV measurements accuracy to about 40 m/s.

In this study we present basic principles and features of RVI2CELL, a precise RV (radial velocity) estimation program to process stellar spectra obtained through iodine cell. RVI2CELL is very robust and fast program. The instrument profile can be modeled as a sum of Gaussian functions or a non-parametric arbitrary shape. The RV accuracy estimated by observation of a RV standard star Tau Ceti indicates about 9 m/s.

We present the result of radial velocity observation of a W UMa type binary star EX Leo. We observed the star on February 16, 2003, using Long-Slit spectrograph of BOAO(Bohyunsan Optical Astronomical Observatory). Since the spectral lines are broad due to its fast rotation, it is difficult to distinguish two radial velocities from cross correlation function. Instead of cross correlation function, we used broadening function to develop our own code which estimate the radial velocity of the broadened line spectra. With our own code, radial velocities of primary and secondary stars are derived simultaneously. From the radial velocity curve fit, we obtained K1=50.24±8.29km/s and K2=254.05±20.984km/s respectively.

By means of magnetic pulsed compaction and sintering of weakly aggregated alumina based nanopowders the jet forming nozzle samples for the hydroabrasive cutting were fabricated. The ceramics was obtained from pure alumina, as well as from alumina, doped by , MgO and AlMg. It was shown that the samples sintered from AlMg doped powder have the best mechanical properties and structural characteristics: relative density , channel microhardness. - 18-20 GPa, channel surface roughness , average crystallite size .