• Title/Summary/Keyword: 쌍극자모멘트

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Development of Magnetic Torquer for Satellite Attitude Control (인공위성 자세제어용 Magnetic Torquer 개발)

  • Son, D.
    • Journal of the Korean Magnetics Society
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    • v.18 no.2
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    • pp.54-57
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    • 2008
  • Magnetic torquer, which uses torque between magnetic dipole moment and earth magnetic field, has been used to control attitude of satellites. In this work, we developed a magnetic torquer for small scientific satellite and test under environmental conditions of the satellite launching and orbital motion have been carried out. The developed magnetic torquer shows saturation magnetic dipole moment of $15Am^2$, linearity of 0.3 % in the range of ${\pm}12Am^2$, mass of 0.46 kg, and power consumption of 1 Watt at magnetic dipole moment of $10Am^2$.

Detection of a Magnetic Dipole by Means of Magnetic Gradient Tensor (자력 변화율 텐서를 이용한 자기 쌍극자 위치 결정)

  • Rim, Hyoung-Rea
    • Journal of the Korean earth science society
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    • v.32 no.6
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    • pp.595-601
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    • 2011
  • In this paper, I propose the algorithm that the location of a magnetic dipole can be detected from the magnetic gradient tensor. I induce the location vector of a vertically magnetizated dipole from the magnetic gradient tensor. Deficit of magnetic moment of magnetic dipole makes the induced location information incomplete. However, if the observation of magnetic gradient tensor would be collected on more points, the algorithm is able to catch the location of the magnetic dipole by clustering the solution of the proposed algorithm. For example, I show that the synthetic case of borehole observation of magnetic gradient tensor can find the source location successively by picking common solution area.

The Effects of the cis and trans Configurations of Ligands on the Calculated Dipole Moments for $[M(II)O_3N_3]$ and $[Ni(II)O_2N_4]$ Type Complexes ($[M(II)O_3N_3]$$[Ni(II)O_2N_4]$ 형태착물의 쌍극자 모멘트에 대한 리간드의 cis 및 trans 구조의 영향)

  • Sangwoon Ahn;Eu Suh Park;Chang Jin Choi
    • Journal of the Korean Chemical Society
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    • v.27 no.2
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    • pp.83-94
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    • 1983
  • The effects of cis and trans configurations of ligands for $[M(II)O_3N_3]$ and $[Ni(II) O_2N_4]$ type complexes [M(II) = Co(III), Ni(II) and Cu(II)] on the calculated dipole moments have been investigated, adpoting the eigenvectors of EHT calculation. The calculated dipole moments for cis complexes are higher than those of trans complexes. The calculated dipole moments for the octahedral trans $[Co(III)O_3N_3]$ type complex fall in the range of experimental values. However the calculated dipole moments for cis $[Ni(II) O_2N_4]$ type complexes fall in the range of the experimental values. These results predicts the trans structure for $[Co(III)O_3N_3]$ and $[Ni(II) O_2N_4]$ type complexes. Those structures are in agreement with the experimental one (Three bidentate (O-N) ligands in $[M(II)O_3N_3]$ type complexes coordinate to the metal ion and two tridentate (O-N-N) ligands in [Ni(II)O2N4] type complexes coordinate to Ni(II) ion).

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Nucleophilic Substitution at a Carbonyl Carbon Atom - Part I. MO-Theoretical Studies on Methyl Chloro-and fluoro-formates

  • Lee, Ikchoon
    • Nuclear Engineering and Technology
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    • v.4 no.4
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    • pp.294-300
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    • 1972
  • CNDO/2 and INDO calculations have been carried out on varying geometries of methyl chloro-and fluoro-formates. Results show that the configuration in which halogen atom is trans to methyl group is the most stable. Atomic charges and overlap population show that the trans form is stabilized by conjugation of carbonyl double bend with the unshared pairs of the ether oxygen and by electrostatic attraction of carbonyl oxygen to methyl group. Dipole moments of the trans forms agree reasonably well with the experimental values but showed that any generalizations made with dipole moments from bond moments should be accepted with considerable reservations.

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Calculation of the Magnetic Moments for Transition Metal Complexes (Ⅱ). The Magnetic Moments for Distorted Octahedral $[V(III)A_3B_3]$ Type Complexes and the Contribution of $^3T_1$ Term to the Dipole Moments and Polarizability [A and B = O, Cl, N or Br] (전이원소착물의 자기모멘트의 계산 (제2보). $t^2_2$ 전자구조를 갖는 일그러진 판면체 $[V(III)A_3B_3]$형태 착물의 자기모멘트와 쌍극자모멘트 및 편극율에 대한 $^3T_1$항의 기여분 [A 와 B = O, Cl, N 또는 Br])

  • Sangwoon Ahn;Se Woung Oh;Kee Hag Lee;Eu Suh Park
    • Journal of the Korean Chemical Society
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    • v.24 no.4
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    • pp.269-279
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    • 1980
  • A method for calulation of the magnetic moments for both octahedral and distorted octahedral $[V(III)A_3B_3]$ type complexes, all with $t^2_2$ configuration, has been developed [A and B = O, Cl, N, F or Br]. The calculated magnetic moments by this method are in reasonable agreements with the experimental values. The calculated magnetic moments for distorted octahedral $[V(III)A_3B_3]$/TEX> type complexes decrease as the extent of tetragonal distortion increases.The effects of k (orbital reduction faction factor), $\xi'$/TEX> and temperature on the magnetic moments are also investigated.A new method for calculation of the contribution of $^3T_1$ molecular orbitals to the dipole moment and polarizability has also developed. The calculated contribution of $^3T_1$ molecular orbitals falls in the reasonable range of values.

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Prediction of Gas Chromatographic Retention Times of PAH Using QSRR (기체크로마토그래피에서 QSRR을 통한 PAH 용리시간 예측)

  • Kim, Young Gu
    • Journal of the Korean Chemical Society
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    • v.45 no.5
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    • pp.422-428
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    • 2001
  • Retention relative times(RRTs) of PAH molecules and their derivatives in gas chromatography are trained and predicted in testing sets using a multiple linear regression(MLR) and an artificial neural network(ANN). The main descriptors of PAHs and their derivatives in QSRR are the square root of molecular weight(sqmw), molecular connectivity($^1{\chi}_v$), molecular dipole moment(D) and length-to-breadth ratios(L/B). The results of MLR shows that a heavy molecule has a propensity for long retention time. L/B closely related with slot model is a good descriptor in MLR. On the other hand, ANN which is not effected by the linear dependencies among the descriptors were exclusively based on molecular weight and molecular dipole moment. The variances which shows the accuracy of prediction for retention times in testing sets are 1.860, 0.206 for MLR and ANN, respectively. It was shown that ANN can exceed the MLR in prediction accuracy.

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Establishment of Bioassay System for Developing New Insecticides I. Effects of Organic Solvents on the Toxicity against Insects, Phytotoxicity and Solubility of Compounds (살충제 개발을 위한 생물검정법의 확립 I. 각종 유기 용매가 곤충의 독성과 약해 및 화합물의 용해성에 미치는 영향)

  • 안용준;조광연
    • Korean journal of applied entomology
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    • v.31 no.2
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    • pp.182-189
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    • 1992
  • The influnces of 9 kinds of solvents on the toxicities against several insect species, phytotoxicity and solubility of compounds were evaluated by means of leaf dipping and spray methods. In case of the spray application, density and vapor pressure seemed to be a contributing factor to lethal toxicity against brown planthopper and diamond-back moth, respectively; the bigger the property of density and the smaller the vapor pressure gave the stronger toxicity. It appeared that the toxicity of solvents was not correlated with anyone of physical properties such as boiling point, dipole moment, dielectric constant, surface tension and viscosity. Spray treatment gave more toxicity to insects than leaf dipping treatment. Although dielectric constant and dipole moment seemed to be contributing factors to phytotoxic damage to rice seedling and bean plants, respectively, no general correlation between phytoxicity and the other physical properties was found. Leaf dipping application caused stronger phytotoxicity than spray application. It is concluded that 5% acetone solution may be most suitable to test chemicals because of its favorable solubility of compounds, lower toxicity to insects, and lower phytotoxicity.

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Stark Effect in Molecular Exciton States (分子 Exciton 狀態에서의 Stark 效果)

  • Jo W. Lee
    • Journal of the Korean Chemical Society
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    • v.19 no.5
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    • pp.304-316
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    • 1975
  • A formal theory to explain the Stark effect in molecular exciton states is developed using the second-quantization formalism. In this theory not only the Stark effect but also the Davydov effect are explicitly taken into consideration since the observed spectral splitting in the UV spectra for molecular crystals with two or more molecules per unit cell may be the result of combination of the above two effects. Especially for molecular crystals containing two molecules in a unit cell the splitting is shown to be hyperbolically dependent upon the strength of an externally applied, uniform electric field, from which informations regarding the excited state dipole moments of a single molecule may be obtained.

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Quantum Chemical Calculations of Surface Hydroxyl Groups as Acid Site (Faujasite 표면 수산기의 산성에 관한 양자화학적 해석)

  • Kim, Myung-Chul
    • Applied Chemistry for Engineering
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    • v.9 no.3
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    • pp.361-363
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    • 1998
  • The CNDO/2 calculations have been applied on cluster models for the representative hydroxyls on faujasite surface to get total energies, dipole moments, Wiberg bond orders and formal charge densities. Quantum chemical calculations indicate that the acid strength of surface hydroxyls of faujasite depends on the geometry of hydroxyls and the Si/Al ratios of framework. The $Br{\ddot{o}}nsted$ acid strength of bridging hydroxyl is higher than that of isolated hydroxyls. The stabilities of cluster models increased with increase of the Si/Al ratios.

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Quantum Chemical Calculations of Silica Hydroxyls as Acid Site (실리카 수산기의 산성에 관한 양자화학적 해석)

  • Kim, Myung Chul
    • Applied Chemistry for Engineering
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    • v.8 no.2
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    • pp.262-266
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    • 1997
  • The CNDO/2 calculations have been applied on cluster models for the representative hydroxyls on silica surface to get Wiberg bond orders, total energies, LUMO energies, dipole moments, and formal charge densities. The Br${\ddot{o}}$nsted acidities of suggested models for the hydroxyls were explained in terms of Wiberg bond orders. The calculated bond orders of cluster models have been changed remarkably according to the hydrogen bond. However the Lewis acidities of terminal hydroxyls on silica surface were not related to the structure of hydroxyls.

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