• 한국자기공명학회논문지
• /
• 제22권4호
• /
• pp.76-81
• /
• 2018

Investigation of the protein-protein interaction mode at atomic resolution is essential for understanding on the underlying functional mechanisms of proteins as well as for discovering druggable compounds blocking deleteriou interprotein interactions. Solution NMR spectroscopy provides accurate and precise information on intermolecular interactions even for weak and transient interactions, and it is also markedly useful for examining the change in the conformation and dynamics of target proteins upon binding events. In this mini-review, we comprehensively describe three unique and powerful methods of solution NMR spectroscopy, paramagnetic relaxation enhancement (PRE), pseudo-contact shift (PCS), and residual dipolar coupling (RDC), for the study on protein-protein interactions.

• Bulletin of the Korean Chemical Society
• /
• 제10권3호
• /
• pp.298-302
• /
• 1989

The strengths of two-photon transitions from the ground state to excited vibronic states in benzene are calculated by using the CNDO/2-U wave functions. The role of vibronic coupling in two-photon absorption process is discussed. The $A_{1{\bar{g}}}-A_{2g}^+$ two-photon transitions, which are forbidden by the identity-forbidden selection rule in single frequency two-photon absorption, are too weak to be experimentally observed even when two photons of different energies are used. It is because the transitions are forbidden also by the pseudo-parity selection rule which are applicable for alternant hydrocarbons such as benzene. It is also shown that the vibronic coupling is not very effective in altering the pseudo-parity property of the electronic state. The strength of the vibronically induced two-photon absorption is strongly affected by the presence of an electronic state from which two-photon absorption can borrow the intensity. It is pointed out that the pseudo-parity selection rule may be violated in such cases.

• 한국강구조학회 논문집
• /
• 제24권4호
• /
• pp.371-382
• /
• 2012

기존의 전단벽 시스템은 커플링보를 강하게 설계하는 경우가 많아 상대적으로 내력 및 강성이 낮은 콘크리트 코어와 특정층에 손상이 발생되기 쉬워 건물의 연성이 저하된다. 전단벽 시스템의 연성능력 및 내진성능을 향상시키기 위해 본 연구에서 강성은 기존의 커플링보 이상으로 발휘되면서 설계하중에 따라 내력을 용이하게 변화시킬 수 있는 강재이력댐퍼를 커플링보에 적용하였다. 강재이력댐퍼는 2단으로 직렬 연결된 형상으로 제안하였고, 제안된 강재이력댐퍼의 구조성능을 검증하기 위하여 정적실험을 수행하였다. 또한 FEM 해석결과를 실험결과와 비교 검증하고 강재이력댐퍼의 초기강성, 에너지 흡수능력, 변형능력 등을 분석하여 설계 근사식을 제안하였다.

• 대기
• /
• 제25권3호
• /
• pp.461-472
• /
• 2015

The sudden stratospheric warming (SSW), which is characterized by an abrupt increase of polar stratospheric temperature by several tens of degrees in a week, has been known to affect tropospheric weather and climate on sub-seasonal time scale in the boreal winter. Such downward coupling has been often examined in North Atlantic and Europe, but rarely examined in East Asia. In this study, by applying the two definitions of SSW to the reanalysis data, the possible impacts of the SSW events on the surface air temperature (SAT) and tropospheric circulation in East Asia are analyzed. It is found that Eurasian continent, including Siberia and the Northeast Asia, tends to experience anomalously cold SAT for up to sixty days after the SSW events. The resulting SAT anomalies largely resemble those associated with negative Artic Oscillation. However, over East Asia, SSW-related SAT change is weak and not statistically significant. Only during the extreme SSW events when the downward coupling between the stratosphere and troposphere is strong, East Asia exhibits significantly cold SAT anomalies. This relationship is presented by grouping SSW events into those followed by cold SAT anomalies over East Asia and those by warm anomalies for varying threshold values of the SSW events.

• Journal of Power Electronics
• /
• 제19권3호
• /
• pp.655-664
• /
• 2019

In order to analyze the nonlinear phenomena of the bifurcation and chaos caused by the switching of nonlinear switching devices in inductively coupled power transfer (ICPT) systems, a Jacobian matrix model, based on discrete mapping numerical modeling, is established to judge the system stability of the periodic closed orbit and to study the nonlinear behavior of Hopf bifurcation in a system under full resonance. The general flow of the parameter design, based on the stability principle for ICPT systems, is proposed to avoid the chaos and bifurcation phenomena caused by unreasonable parameter selection. Firstly, based on the state equation of SS-type compensation, a three-dimensional bifurcation diagram with the coupling coefficient as the bifurcation parameter is established with a numerical simulation to observe the nonlinear phenomena in the system. Then Filippov's method based on a Jacobian matrix model is adopted to deduce the boundary of stable operation and to judge the type of the bifurcation in the system. Then the general flow of the parameter design based on the stability principle for ICPT systems is proposed through the above analysis to realize stable operation under the conditions of weak coupling. Finally, an experimental platform is built to confirm the correctness of the numerical simulation and modeling.

• 한국컴퓨터정보학회논문지
• /
• 제15권10호
• /
• pp.99-104
• /
• 2010

본 논문은 PIFA의 방사체와 접지면의 물리적 변화없이 안테나의 결합 계수와 공진 주파수를 조절할 수 있는 이동 통신 단말기용 내장형 안테나를 제안하였다. 제안된 안테나는 하나의 단락점에 추가된 인덕턴스에 따라 급전점과 단락점 사이의결합계수 뿐만 아니라 안테나의 공진 주파수도 조절한다. 제안된방법은 전계의 세기가 약한단락점에 인덕터를 연결하여 안테나의 성능 변화를 최소화 했다. PIFA의 단락점과 접지면 사이에 추가된 인덕터의 값이 0nH ~ 3.3nH로 변할 때 조절 가능한 공진 주파수 범위는 1650MHz ~ 1830MHz (약 180MHz)이고 인덕터의 값이 커질수록 안테나의 결합계수는 커진다. 이를 통하여 이동 통신 단말기의 형태 및 사용자의 환경에 따른 임피던스 및 공진 주파수의 변화를 전기적으로 조절하여 부정합에 의한 손실을 최소화했고 안테나 방사 성분의 어떠한 변형 없이 10%의 크기 감소효과를 얻을 수 있다. 1650MHz ~ 1830MHz의 주파수 영역에서 측정된 PIFA의 이득 감소는 0 ~ 3.3nH의 인덕터 값의 변화에 따라 0.93dB 이내이다.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2000년도 추계학술대회논문집A
• /
• pp.529-534
• /
• 2000

A finite element analysis for a rotating cantilever beam is presented in this study. Based on a dynamic modelling method using the stretch deformation instead of the conventional axial deformation, three linear partial differential equations are derived from Hamilton's principle. Two of the linear differential equations show the coupling effect between stretch and chordwise deformations. The other equation is an uncoupled one for the flapwise deformation. From these partial differential equations and the associated boundary conditions, are derived two weak forms: one is for the chordwise motion and the other is for the flapwise motion. The weak forms are spatially discretized with newly defined two-node beam elements. With the discretized equations or the matrix-vector equations, the behaviours of the natural frequencies are investigated for the variation of the rotating speed.

• Current Applied Physics
• /
• 제18권11호
• /
• pp.1338-1344
• /
• 2018

Band parameters and superconductivity of yttrium hypocarbide ($Y_2C$) have been investigated. The computations are performed using first-principles pseudopotential method within a generalized gradient approximation. The equilibrium lattice parameters have been determined and compared with experiment. Moreover, the material of interest is found to be stiffer for strains along the a-axis than those along the c-axis. A band-structure analysis of $Y_2C$ implied that the latter has a metallic character. The examination of Eliashberg Spectral Function indicates that Y-related phonon modes as well as C-related phonon modes are considerably involved in the progress of scattering of electrons. By integrating this function, the value of the average electron-phonon coupling parameter (${\lambda}$) is found to be 0.362 suggesting thus that $Y_2C$ is a weak coupling Bardeen-Copper-Schrieffer superconductor. The use of a reasonable value for the effective Coulomb repulsion parameter (${\mu}^*=0.10$) yielded a superconducting critical temperature $T_c$ of 0.59 K which is comparable with a previous theoretical value of 0.33 K. Upon compression (at pressure of 10 GPa) ${\lambda}$ and $T_c$ are increased to be 0.366 and 0.89 K, respectively, showing thus the pressure effect on the superconductivity in $Y_2C$. The spin-polarization calculations showed that the difference in the total energy between the magnetic and non-magnetic $Y_2C$ is weak.

• 전기학회논문지P
• /
• 제55권3호
• /
• pp.141-145
• /
• 2006

The line current problem(2-dimensional space : point source) is not easy to analyze the magnetic field using the standard finite element method(FEM), such as overhead trolley line or transmission line. To supplement such a defect this paper is proposed the coupling scheme of analytical solution and FEM. In analysis of the magnetic field using the standard FEM. If the current region is a relatively small compared to the whole region. Therefore the current region must be finely divided using a large number of elements. And the large number of elements increase the number of unknown variables and the use of computer memories. In this paper, an analytical solution is suggested to supplement this weak points. When source is line current and the part of interest is far from line current, the analytical solution can be coupling with FEM at the boundary. Analytical solution can be described by the multiplication of two functions. One is power function of radius, the other is a trigonometric function of angle in the cylindrical coordinate system. There are integral constants of two types which can be established by fourier series expansion. Also fourier series is represented as the factor to apply the continuity of the magnetic vector potential and magnetic field intensity with tangential component at the boundary. To verify the proposed algorithm, we chose simplified model existing magnetic material in FE region. The results are compared with standard FE solution. And it is good agreed by increasing harmonic order.

• 항공우주시스템공학회지
• /
• 제14권1호
• /
• pp.16-20
• /
• 2020

차량이 주행 중에 그리고 항공기가 활주로에 착륙하는 순간과 활주 중에 발생하는 피로는 착륙장치, 기체와 차량의 현가장치 등에 수명 주기와 밀접한 관련이 있다. 휠에 작용하는 하중들은 종축 힘, 횡력, 수직력과 제동력이다. 차량의 동특성과 내구성을 연구하기 위해 본 논문의 시뮬레이터는 시험실에서 실제 노면 형상을 재현에 사용된다. 그러므로 제품 개발 시간과 비용을 절감할 수 있다. 하드웨어적으로 유압 피로 시뮬레이터 구조의 중요한 요소는 각 축을 분리하고 여러 하중과 진동을 견뎌내는 것이다. 본 논문의 역기구학적 해석 방법은 Dummy wheel 중심에서 축 방향으로 최대 동작 변위를 준 후 커플링에 의한 유압 서보 작동기의 작동 크기를 도출한다. 해석의 결과는 실제 노면 형상을 정확하게 재현하기 위해 축 간의 커플링이 미약함을 확인하는 것이다.