• Title/Summary/Keyword: Spin modes

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Reaction Condition Dependency of Propagating Behavior in the Polymerization Reaction by Thermal Front

  • Huh, Do-Sung;Choe, Sang-Joon;Lee, Burm-Jong
    • Bulletin of the Korean Chemical Society
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    • v.23 no.2
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    • pp.325-329
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    • 2002
  • In this study, the dependency of the behavior of propagating front on the reaction condition in frontal polymerization reaction has been studied. We have used some multifunctional acrylates as a monomer and ammonium persulfate as an initiator for the polymerization reactions. In frontal polymerization, a method of producing polymeric materials via a thermal front that propagates through the unreacted monomer/initiator solution, the behavior of self propagating front shows various dynamic patterns depending on the reaction condition. We have obtained some spin modes of propagating front in the number of 'hot spots' or 'spin heads' by changing the reaction condition. The effect of the reactor tube diameter on the mode of propagating front has also been studied by using some reactor tubes with different size of tube diameter and it has been examined in some detail by adopting an experimental method of two-tubes system.

Two Dimensional Transfer Modes in $CH_2$ Spin System

  • NamGoong Hyun
    • Journal of the Korean Magnetic Resonance Society
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    • v.10 no.1
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    • pp.59-73
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    • 2006
  • Spin-lattice relaxation pathway of $CH_2$ spin system by two dimensional NOESY sequence has been discussed. Two-dimensional spectra governed by dipolar relaxation mechanism were simulated in term of transfer mode, the generalization of conventionally used magnetization mode in one dimension. The transfer matrix directly related to the Redfield relaxation matrix can be constructed by the multiplet of transfer mode. The observable relaxation transfer modes causes to variation of the off-diagonal signal intensity of phase sensitive NOESY spectra from which variable spectral density can be extracted with simple group theoretical calculation. The variation of the J-coupling peak intensity as a function of the mixing time in 2-D spectra for $n-Undecane-5-^{13}C$ and Bromoacetic $2-^{13}C$ acid has been theoretically traced.

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Impact Analysis of the Cervical Spin using a Finite Element Model (유한요소 모델을 이용한 충격력에 따른 경추부의 응답특성 해석)

  • 김영은;박덕용;이춘기
    • Transactions of the Korean Society of Automotive Engineers
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    • v.7 no.5
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    • pp.249-257
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    • 1999
  • A three dimensional finite model of a human neck has been developed in an effort to study the mechanics of cervical spin while subjected to vertical impact. This model consisting of the vertebrae from C1 through C7 including posterior element and ligaments was constructed by 2mm thick transverse CT cross-sections and X-ray film taken at lateral side. Geometrical nonlinearity was also considered for the large deformation on the disc. ABAQUS package was used for calculation and its results were verified comparing with responses of a model under static loading condition with published in-vitro experimental data. There were more cervical fracture in the restrained (compression) mode than in the nonrestrained (flexion-compression and extension-compression) mode. Upper cervical(C1-C2) injuries were observed under compression-extension modes, while lower cervical injuries occurred undjer compression-flexion modes. Posterior ligament distraction without bony damage at the upper cervical spin(C1-C2) were observed secondary to C5-C7 trauma in compression-flexion modes.

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An NMR Study on Molecular Motions of $\alpha$,2,6-Trichlorotoluene in Solution State

  • Ahn, Sang-Doo;Lee, Jo-Woong
    • Bulletin of the Korean Chemical Society
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    • v.15 no.7
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    • pp.553-559
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    • 1994
  • Dynamics of $CH_2CI$ group in ${\alpha},2,6$-trichlorotoluene dissolved in $CDCl_3$ was studied by observing various relaxation modes for $^{13}C$ under proton undecoupled condition. Partially relaxed $^{13}C$ spectra were obtained at $34^{\circ}C$ as a function of evolution time after applying various designed pulse sequences to this $AX_2$ spin system. It was found that nonlinear regression analysis of the relaxation data for these magnetization modes could provide the information about dipolar and spin-rotational auto-correlation and cross-correlation spectral densities for fluctuation of the $^{13}C-^1H$ internuclear vector in $CH_2Cl$ group. The results show that the effect of cross-correlation is comparable in magnitude to that of auto-correlation and the relaxation in this spin system is dominated by dipolar mechanism rather than spin-rotational one. From the resulting spectral density data we could calculate the bond angle ${\angle}HCH\;(105.1$^{\circ}$) and elements of the rotational diffusion tensor for $CH_2Cl$ group.

Evidence of spin-phonon coupling in La2NiMnO6 double perovskite

  • Nasir, Mohammad;Ahmed, Ateeq;Park, Hee Jung;Sen, Somaditya
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.31 no.3
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    • pp.112-115
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    • 2021
  • Herein, a correlation between B-site cation order and spin-phonon coupling in La2NiMnO6 double perovskite has been investigated. Raman spectra of La2NiMnO6 double perovskite annealed at 950 and 1400℃ have been measured in the 140-598 K range. A substantial softening of the phonon modes has been observed below the Curie temperature, which emphasized the presence of the spin-phonon coupling in the system. The spin-phonon coupling was found to be stronger in relatively more ordered La2NiMnO6 double perovskite. Thus, the magnitude of spin-phonon coupling was influenced by the Ni/Mn cation order.

The Analysis of Device Models and the Method of Increasing Compatibility Between Device Models for M&S V&V of NetSPIN (NetSPIN M&S 모델 V&V를 위한 장비 모델 및 모델간 호환성 증진방안 분석)

  • Park, In-Hye;Kang, Seok-Joong;Lee, Hyung-Keun;Shim, Sang-Heun
    • Journal of Information Technology Services
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    • v.11 no.sup
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    • pp.51-60
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    • 2012
  • In this paper, we provide the analysis of device model and method between device models for compatible M&S V&V of the NetSPIN. First of all, we analysis features, structure, and classification of the NetSPIN. The second, as a part of reliable V&V process, we analysis network system modeling process, correlation between device modeling process for M&S of the NetSPIN. The third, we suggest making a kind of pool of reference model and module of devices for the increase factor of reuse between device model. We also, at the point view of M&S V&V, conclude that there is the validity of the fidelity in device modeling process. Through the analysis of the NetSPIN device model and suggestion of the method for higher compatibility between device modes, the development process of device model be clearly understood. Also we present the effective method of the development for reliable device mode as the point of V&V.