• Journal of Astronomy and Space Sciences
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• 제30권3호
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• pp.133-140
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• 2013

Most of high energy cosmic rays (CRs) are thought to be produced by diffusive shock acceleration (DSA) at supernova remnants (SNRs) within the Galaxy. Fortunately, nonthermal emissions from CR protons and electrons can provide direct observational evidence for such a model and place strong constraints on the complex nonlinear plasma processes in DSA theory. In this study we calculate the energy spectra of CR protons and electrons in Type Ia SNRs, using time-dependent DSA simulations that incorporate phenomenological models for some wave-particle interactions. We demonstrate that the time-dependent evolution of the self-amplified magnetic fields, Alfv$\acute{e}$nic drift, and escape of the highest energy particles affect the energy spectra of accelerated protons and electrons, and so resulting nonthermal radiation spectrum. Especially, the spectral cutoffs in X-ray and ${\gamma}$-ray emission spectra are regulated by the evolution of the highest energy particles, which are injected at the early phase of SNRs. Thus detailed understandings of nonlinear wave-particle interactions and time-dependent DSA simulations of SNRs are crucial in testing the SNR hypothesis for the origin of Galactic cosmic rays.

• BMB Reports
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• 제38권2호
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• pp.243-247
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• 2005

Dishevelled (Dvl) is a positive regulator of the canonical Wnt signaling pathway, which regulates the levels of $\beta$-catenin. The $\beta$-catenin oncoprotein depends upon the association of Dvl and Axin proteins through their DIX domains, and its accumulation directs the expression of specific developmental-related genes at the nucleus. Here, the $^1H$, $^{13}C$, and $^{15}N$ resonances of the human Dishevelled 2 DIX domain are assigned using heteronuclear nuclear magnetic resonance (NMR) spectroscopy. In addition, helical and extended elements are identified based on the NMR data. The results establish a structural context for characterizing the actin and phospholipid interactions and binding sites of this novel domain, and provide insights into its role in protein localization to stress fibers and cytoplasmic vesicles during Wnt signaling.

• 한국자기학회지
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• 제3권3호
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• pp.173-178
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• 1993

스피넬구조를 갖는 $AB_{2}O_{4}$에서 A-O-B초교환 상호작용을 고려하여 A(사면체)와 B(팔면체) 자리에 들어 있는 자성원자(Fe)의 환산자발자화와 그 평균치를 환산온도의 함수로 계산하였다. 그 결과를 A-B직접 상호작용을 고려하여 계산한 환산자발자화의 온도의존성과 비교하였다. 보다 정확한 비교를 위하여 두가지 경우에 대한 $M\"{o}ssbauer$ 스펙트럼을 계산하였다.

• Journal of Astronomy and Space Sciences
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• 제17권2호
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• pp.317-328
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• 2000

The solar wind contributes to the formation of unique space environment called the Earth's magnetosphere by various interactions with the Earth's magnetic field. Thus the solar-terrestrial environment affects the Earth's magnetic field, which can be observed with an instrument for the magnetic field measurement, the magnetometer usually mounted on the rocket and the satellite and based on the ground observatory. The magnetometer is a useful instrument for the spacecraft attitude control as well as the Earth's magnetic field measurements for the spacecraft purpose. In this paper, we present the preliminary design and test results of the two onboard magnetometers of KARI's (Korea Aerospace Research Institute) sounding rocket, KSR-3, which will be launched four times during the period of 2001-02. The KSR-3 magnetometers consist of the fluxgate magnetometer, MAG/AIM (Attitude Information Magnetometer) for acquiring the rocket flight attitude information, and of the search-coil magnetometer, MAG/SIM (Scientific Investigation Magnetometer) for the observation of the Earth's magnetic field fluctuations. With the MAG/AIM, the 3-axis attitude information can be acquired by the comparison of the resulting dc magnetic vector field with the IGRF (International Geomagnetic Reference Field). The Earth's magnetic field fluctuations ranging from 10 to 1,000 Hz can also be observed with the MAG/SIM measurement.

• 한국자기공명학회논문지
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• 제20권1호
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• pp.22-26
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• 2016

FANCJ is a DNA helicase which contributes genome stability by resolving G-quadruplex DNA from 5' to 3' direction. In addition to main ATPase helicase core, FANCJ has the protein binding region at its C-terminal part. BRCA1 and BLM are the binding partner of FANCJ and these protein-protein interactions contribute genomic stability and the proper response to replication stress. As the first attempt for studying FANCJ-BLM interaction, we prepared BLM binding region of FANCJ and characterized with CD and NMR spectroscopy. FANCJ (881-941) with N-ter 6xHis was purified as the oligomer. Secondary structure prediction based on CD data revealed that FANCJ (881-941) composed with ${\beta}$ sheet, turn and coils.$^1H-^{15}N$ HSQC spectra showed nonhomogeneous peak intensities with less number of peaks comparing than the number of amino acids in the construct. It indicated that optimization should be necessary for detailed further structural studies.

• 한국자기공명학회논문지
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• 제18권1호
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• pp.1-4
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• 2014

It is generally understood that protein-protein interactions proceed via transient encounter complexes that rapidly evolve into the functional stereospecific complex. Direct detection and characterization of the encounter complexes, however, been difficult due to their low population and short lifetimes. Recent application of NMR paramagnetic relaxation enhancement first visualized the structures of the encounter complex ensemble, and allowed the characterization of their physicochemical properties. Further, rational protein mutations that perturbed the encounter complex formation provided a clue to the target search pathway during protein-protein association. Understanding the structure and dynamics of encounter complexes will provide useful information on the mechanism of protein association.

• 한국자기공명학회논문지
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• 제18권1호
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• pp.5-9
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• 2014

In last three decades, RNA molecules have been revealed to play the central roles in many cellular processes. Structural understanding of RNA molecules is essential to interpret their functions, and many biophysical techniques have been adopted for this purpose. NMR spectroscopy is a powerful tool to study structures and dynamics of RNA molecules, and it has been further applied to study tertiary interactions between RNA molecules, RNA-protein, and RNA-small molecules. This short article accounts for the general methods for NMR sample preparations, and also partially covers the resonance assignments of structured RNA molecules.

• 한국자기공명학회논문지
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• 제11권2호
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• pp.110-114
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• 2007

[ $^{31}P$ ] powder pattern spectra were measured to investigate the aspects of the interaction between the MLV (Multilamellar vesicle) and PMAP-23, a membrane of cathelicidin family and then CSAs(chemical shift anisotropy) were calculated to indentify the extent of perturbation of phospholipid mobility by the peptides. We found that acidic phospholipid interacts strongly with PMAP-23, and the analogues which modified to increase the amphipathic property showed that larger change of CSA. The analogue which introduced positive charge showed the same effects with amphipathic property.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2006년도 추계학술대회 특별세미나 특별세션
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• pp.135-144
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• 2006

To investigate various running performances of the magnetic levitation train systematically, the performance evaluation system based on Modeling & Simulation(M&S) technology is demanded essentially When the VR(virtual reality) techniques are involved, we can not only evaluate the M&S results more effectively and realistically, but also make optimum engineering decision. At the viewpoint of visualization of core engineering data like the train's running performance, there are no many cases of study which provide optimum decision information with the maximized reality and immersion environments through computer user interactions. In this study, the running performance simulation system which provides the VR based 3-dimensional visual information from the M&S results is being developed.

• 천문학회보
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• 제43권1호
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• pp.56.2-56.2
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• 2018

Astrophysical shocks accelerate particles to high velocities, which we observe as cosmic rays. The acceleration process changes the nature of the shock because the particles interact with the local magnetic field, removing energy and potentially triggering instabilities. In order to simulate this process, we need a computational method that can handle large scale structures while, at the same time, following the motion of individual particles. We achieve this by combining the grid magnetohydrodynamics (MHD) method with the particle-in-cell (PIC) approach. MHD can be used to simulate the thermal gas that forms the majority of the gas near the shock, while the PIC method allows us to model the interactions between the magnetic field and those particles that deviate from thermal equilibrium. Using this code, we simulate shocks at various sonic and Alfvenic Mach numbers in order to determine how the behaviour of the shock and the particles depends on local conditions.