• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• v.1
• /
• pp.191-196
• /
• 2006

In GPS Positioning, the error of satellite orbit will affect user's position accuracy directly, it is important to determine the satellite orbit precise. The real-time orbit is needed in kinematic GPS positioning, the precise GPS orbit from IGS would be delayed long time, so orbit prediction is key to real-time kinematic positioning. We analyze the GPS predicted ephemeris, on the base of comparison of EKF and UKF, a new orbit prediction method is put forward based on UKF in this paper, the result shows that UKF improves the orbit predicted precision and stability. It offers a new method for others satellites orbit determination as Galileo, and so on.

• Bulletin of the Korean Chemical Society
• /
• v.17 no.9
• /
• pp.849-853
• /
• 1996

Hetero Dieis-Alder reactions containing phosphorus atom at various positions of diene and dienophile as well as standard Dieis-Alder reaction between ethylene and cis-l,3-butadiene have been studied using ab initio method. Activation energy showed a good linear relationship with the FMO energy gap between diene and dienophile, which can be normally used to explain Dieis-Alder reactivity. Since π-bond cleavage and σ-bonds formation occur concertedly at the TS, geometrical distortion of diene and dienophile from the reactant to the transition state is the source of barrier. Based on the linear correlations between activation barrier and deformation energy, and between deformation energy and π-bond order change, it was concluded that the activation barrier arises mainly from the breakage of π-bonds in diene and dienophile. Stabilization due to favorable orbital interaction is relatively small. The geometrical distortions raise MO levels of the TS, which is the origin of the activation energy. The lower barrier for the reactions of phosphorus containing dienophile (reactions C, D, and E) can be explained by the electronegativity effect of the phosphorus atom.

• Bulletin of the Korean Chemical Society
• /
• v.16 no.3
• /
• pp.226-232
• /
• 1995

The electronic structures of the C60, (H3P)2Pt(η2-C2H4) and (H3P)2Pt(η2-C60) are calculated by using the EHMO method with the fragment analysis. We have modified the EHT parameters so as to yield the orbital energy level correlation and to fit the optical transition gap to the previous theoretical results of C60. In Pt-derivatives, our FMO results with the modified parameters show that the carbon-carbon double bonds of C60 and ethene react like those of electron-poor arenes and alkenes, and also that C60 is more electron-susceptive than C2H4.

• Bulletin of the Korean Chemical Society
• /
• v.32 no.6
• /
• pp.1980-1984
• /
• 2011

A temperature- and coverage-dependant quasi-reversible change in two-photon photoemission (2PPE) of chemisorbed 1-phenyl-1-propyne (PP) on Cu(111) is reported. For PP on Cu(111) at 300 K probed at a photon energy of 4.13 eV, two broad peaks of comparable intensity show final state energies of 7.25 and 7.75 eV above the Fermi level. The former peak could be assigned to the first image potential state (IS, n = 1) and/or unoccupied molecular orbital (UMO), located at 3.1 eV above the Fermi level. The latter is plausibly attributed to a mix of unoccupied higher-order IS (and/or UMO) and occupied surface state (SS) of Cu(111). With decreasing the temperature, the former 2PPE peak shows a shift in position by about 0.2 eV, and the latter exhibits a dramatic increase in intensity. In the system, intermolecular interactions (and/or order-disorder transition) of PP and substrate lattice temperature may play a significant role in change in photoexcitation lifetime (or excitation cross-section), and the unoccupied molecular orbital (UMO)-metal (IS) charge transfer coupling. Our unique 2PPE results provide a deeper insight for understanding photoexcitation charge transfer with temperature in an organic molecule/metal system.

• Journal of the Korean Chemical Society
• /
• v.33 no.6
• /
• pp.571-576
• /
• 1989

The relativistically parameterized Extended Huckel (REX) calculations are carried out for $[M(NH_3)_5Cl]^{2+}$ (M = Cr, Co, Ru, Rh, Os, Ir). The calculated orbital and overlap populations agree with experimental data. The REX calculations on the electronic structure have been also compared with nonrelativistic EHT results. A ${\phi}$-bonding in M-Cl bond is founded to be more important for the $d^3$, $d^5$complexes than the $d^6$ system.

• Publications of The Korean Astronomical Society
• /
• v.30 no.2
• /
• pp.605-607
• /
• 2015

The development of time-frequency analysis techniques allow astronomers to successfully deal with the non-stationary time series that originate from unstable physical mechanisms. We applied a recently developed time-frequency analysis method, the Hilbert-Huang transform (HHT), to two non-stationary phenomena: the superorbital modulation in the high-mass X-ray binary SMC X-1 and the quasi-periodic oscillation (QPO) of the AGN RE J1034+396. From the analysis of SMC X-1, we obtained a Hilbert spectrum that shows more detailed information in both the time and frequency domains. Then, a phase-resolved analysis of both the spectra and the orbital profiles was presented. From the spectral analysis, we noticed that the iron line production is dominated by different regions of this binary system in different superorbital phases. Furthermore, a pre-eclipse dip lying at orbital phase ~0:6-0:85 was discovered during the superorbital transition state. We further applied the HHT to analyze the QPO of RE J1034+396. From the Hilbert spectrum and the O-C analysis results, we suggest that it is better to divide the evolution of the QPO into three epochs according to their different periodicities. The correlations between the QPO periods and corresponding fluxes were also different in these three epochs. The change in periodicity and the relationships could be interpreted as the change in oscillation mode based on the diskoseismology model.

• Journal of Astronomy and Space Sciences
• /
• v.20 no.1
• /
• pp.21-28
• /
• 2003

In case that we independently obtain orbital informations about the low earth satellites of foreign countries using radar systems, we develop the orbit determination algorithm for this purpose using a SGP4 model with an analytical orbit model and the extended Kalman filter with a real-time processing method. When the state vector is Keplerian orbital elements, singularity problems happen to compute partial derivative with respect to inclination and eccentricity orbit elements. To cope with this problem, we set state vector osculating to mean equinox and true equator cartesian elements with coordinate transformation. The state transition matrix and the covariance matrix are numerically computed using a SGP4 model. Observational measurements are the type of azimuth, elevation and range, filter process to each measurement in a lump. After analyzing performance of the developed orbit determination algorithm using TOPEX/POSEIDON POE(precision 0.bit Ephemeris), its position error has about 1 km. To be similar to performance of NORAD system that has up to 3km position accuracy during 7 days need to radar system performance that have accuracy within 0.1 degree for azimuth and elevation and 50m for range.

• Journal of the Korean Chemical Society
• /
• v.36 no.1
• /
• pp.3-15
• /
• 1992

Electronic structures and reactivities of the chromium, molybdenum, and tungsten carbene complexes, $(CO)_5Cr=CCHCH_2(XCH_3)\;,\;(CO)_5Mo=CCHCH_2(XCH_3)\;, and\;(CO)_5W=CCHCH_2(XCH_3)$, are studied by means of Extended Huckel calculations. The origin of the M=Ccarbene double bond is clarified from the diagram of the orbital correlation with the fragment orbitals. The ${\sigma}$ bond of the M=Ccarbene double bond is formed by the electron transfer interaction from the HOMO of the carbene to the LUMO of the $(CO)_5M$. The ${\pi}$ bond is formed through the back-transfer of electrons from one of the degenerated d${\pi}$ orbitals to the LUMO of the carbene. The polarization of charge of the M=Ccarbene bond is calculated to be M=Ccarbene for Mo, and W carbenes. The chemical and physical properties of these complexes are resulted from an appreciable positive charge on the carbene carbon. The electrophilic reactivity of the carbene carbon is not charge controlled, but is controlled by the frontier orbital, LUMO.

• Bulletin of the Korean Chemical Society
• /
• v.14 no.5
• /
• pp.549-554
• /
• 1993

The CO substitution reactions in the complex, $Cp^*(C_5H_7)$CrCO with $PR_3(PR_3=PMePh_2,\;P(OCH_3)_3,\;PMe_2Ph)$ were investigated spectrophotometrically at various temperatures. For the reaction rates, it was suggested that the CO substitution reaction took place by first-order (dissociative) pathway. Activation parameters in decaline are ${\Delta}H^{\neq}= 21.99{\pm}2.4$ kcal/mol, ${\Delta}S^{\neq}= 8.9{\pm}7.1$ cal/mol·k. Unusually low value of ${\Delta}S^{\neq}$, suggested an ${\eta}^5-S{\to}\;{\eta}^5$-U conversion of the pentadienyl ligand. At various temperature, the rates of reaction for the Cp(pdl)CrCO complexes increase in the order $Cp^*(C_5H_7)$-CrCO < Cp$(C_5H_7)$CrCO < Cp(2,4-$C_5H_{11}$)CrCO, which can be attributed to the usual steric acceration or electronic influence for the ligand substitution of metal complexes. This suggestion was confirmed by the extended-Huckel molecular orbital (EHMO) calculations, which revealed that the energy of $[Cp^*(U-C_5H_7)Cr]^{\neq}$ transition state is about 4.93 kcal/mol lower than that of [Cp(S-$C_5H_7)Cr]^{\neq}$ transition state, and the arrangement of the overlap populations between Cr and the carbon of CO is $Cp^*(C_5H_7)$CrCO > Cp($C_5H_7$)CrCO > Cp(2,4-$C_7H_{11}$)CrCO.

• The Journal of the Convergence on Culture Technology
• /
• v.7 no.2
• /
• pp.389-394
• /
• 2021

In this work, we study the properties of molecular structure and boundary orbital functions of the DPHMP-AlH and propiophenone and butyrophenone, which are forms of alkoxy-amine-aluminum derivatives. Furthermore, we investigate the effect on the selective reduction of the final products (R), (S)-phenylpropanol and (R), (S)-phenylbutanol by calculating the stereoscopic and thermodynamic parameters of the transition state. Considering the three-dimensional molecular structural stability, the transition status of (S) types DPHMP-AlH and alkylphenone was found to be more stable, resulting in the selective reductions of DPHM-AlH and alkylphenone from this result: (S)-(1)-phenylpropanol and (S)-(1)-phenylbutanol was confirmed that the formation was advantageous.