• 생약학회지
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• 제11권3_4호통권43호
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• pp.153-162
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• 1980

1) The hydroxy-substitution in the simple phenolic compounds follows an additivity rule in the chemical shifts of their aromatic carbon atoms. In para-and ortho-effects is a good agreement between calculated and measured values, but the meta-effect is not certain. 2) The additivity rule was applied to assign the chemical shifts of catechins. 3) The nuclear overhauser effect was applied to assign the chemical shifts of C-8 and C-6 atoms of catechins and their polymer. The signal of C-8 is lower in intensity and appear in lower field than C-6. 4) The results of the NOE were applied to determine the bonding positions of catechin units in the catechin dimer and trimer. The bonding positions are C-8a and C-8b atoms of the second and third catechin units. 5) It was tried to determine the conformation of the catechin dimer and trimer by analysing the signal shapes of C-3' and C-4' atoms in the catechol moieties. The catechol moieties lie in opposite side in the dimer and trimer structure. A combined analysis of $^{13}C-and\;^1H-NMR$ results lead to the suggestion that such a catechin polymer is a zigzag planar form.

• 한국광학회지
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• 제4권3호
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• pp.354-358
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• 1993

지그재그 슬랩 레이저의 글라스 내부 온도분포를 마하-젠더 간섭계로 측정하였다. 슬랩 레이저글라스의 파괴 원인은 슬랩글라스의 표면과 중심부의 온도차로 이 온도차 ${\Delta}T_0$가 $110^{\circ}C$, $62^{\circ}C$에서 두 장의 레이저글라스가 파괴되었다. 고평균출력 글라스레이저를 설계하는데 있어서 안전 작동을 이하여 슬랩글라스 표면과 중심부의 온도차 ${\Delta}T_0$가 $50^{\circ}C$를 넘지 않도록 해야한다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제40회 동계학술대회 초록집
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• pp.442-442
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• 2011

Electronic and magnetic properties of bilayer zigzag graphene nanoribbon (bZGNR) are studied using pseudopotential density functional method. The edge atoms in the top and bottom layers of bZGNR make a weak hybridization, which leads to electronic structures different from monolayer ZGNR. For asymmetric bZGNR, where the top and bottom layers have different widths, one edge is pinched by the interlayer bonding and the other sustains antiferromagnetic ordering. A small amount of charge transfer occurs from narrower to wider layer, producing spin-polarized electron and hole pockets. External electric field produces asymmetric energy-gap opening for each spin component, inducing half-metallicity in bZGNR.

• EDISON SW 활용 경진대회 논문집
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• 제3회(2014년)
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• pp.446-449
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• 2014

Carbon Nanotube (CNT) have been intensively investigated since they have been considered as building blocks of nanoscience and nanotechnology. Theoretical and computational studies on CNTs have revealed their physical and chemical properties and helped researchers build various experimental devices to study them in depth. However, there have been only few systematic studies on detailed changes in electronic structures of CNTs due to geometrical structure modifications. In this regard, it is necessary to perform systematic investigations of the modifications in electronic structures of CNTs, as their geometrical configurations are altered, using the first-principles density functional theory. In other words, it is essential to determine the true equilibrium structure of CNTs. In this work, we considered the different atomic configurations by maintaining their symmetries, but changing all the inequivalent bonding types one by one. Furthermore, as for CNTs, for example, the way the graphene sheet is wrapped is represented by a pair of indices (n,m) and electronic structures of CNTs vary depending on different indices. Our results suggest all the significant couplings between electronic and geometric structures in CNTs.

• EDISON SW 활용 경진대회 논문집
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• 제6회(2017년)
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• pp.376-382
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• 2017

Graphene nanoribbons with zigzag-shaped edge (zGNRs) are predicted to be magnetic insulator at the ground state, attracting significant interest in view of spintronic applications [1]. On the other hand, although they are energetically and thermodynamically more favored than zGNRs [2], graphene nanoribbons with armchair-shaped edge (aGNRs) have been less spotlighted than zGNRs due to the absence of magnetism. Herein, based on the combined density functional theory (DFT) and matrix Green's function (MGF) approach, we consider aGNRs functionalized with various molecular groups, and show that the spin polarizations develop for some of the considered aGNR edge functionalization cases. The origin of the induced magnetism will be discussed within the Lieb's theorem [3]. This work will provide a novel guidance for the development of graphene-based spintronic devices.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2000년도 제1회 학술대회 논문집
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• pp.235-238
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• 2000

We have performed ab initio pseudopotential electronic structure calculations for various edge geometries of the (n,n) singlewall nanotube with on without applied fields. Among the systems studied, the one with the zigzag edge exposed by a slant out is found to be the most favorable for the emission due to the existence of unpaired dangling bond states around the Fermi level. The next favorable geometry is the capped nanotube where ${\pi}-bonding$ states localized at the cap and pointing to We tube axis direction occur at the Fermi level. A scaling rule of the induced field linean in the aspect ratio of the tube is also obtained.

• Journal of Ship and Ocean Technology
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• 제3권3호
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• pp.25-44
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• 1999

Estimation efficiencies according to different sea trial are investigated in connection with sensitivity analysis, and new trial method is proposed which can improve the estimation efficiency of hydrodynamic derivatives. MMG Equation with Kijima's formula is used for simulation. Extended Kalman Filter is chosen for estimation technique and hydrodynamic derivatives of interest is limited to 12 of those in sway and yaw equations. Esso Osaka is selected for the test ship. Sensitivity analysis and estimation results based on conventional trials show that a more sensitive derivative gives more efficient estimation result. Sensitivities of nonlinear derivatives become pronounced in the trial where steady condition lasts longer such as turning test, while sensitivities of linear derivatives gas a larger values in the trial where unsteady condition lasts longer such as 10deg-10deg zigzag test. Consequently, in new method , named S-type trial, steady and unsteady condition are combined appropriately to increase sensitivities. Linear derivatives are estimated better in S-type trial and the estimation of nonlinear derivatives is improved to extent.

• International Journal of Naval Architecture and Ocean Engineering
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• 제11권2호
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• pp.865-874
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• 2019

A controller for an underwater glider is presented. Considered underwater glider is a torpedo-shaped autonomous underwater vehicle installing adjustable buoyancy bag and movable battery in it. The controller is composed of an LQR controller to maintain zigzag vertical movement for gliding and two PD controllers to control elevator/rudder angles. The LQR controller controls the pumping speed into the buoyancy bag and the moving speed to locate the battery. One of the PD controller controls the elevator angle to assist the LQR controller, and the other controls the rudder angle to adjust the direction of the underwater glider. A reduced order Luenberger observer is adopted to estimates the center of gravity of the glider and the buoyancy mass that are essential but cannot be measured. Mathematical simulation using Matlab proved the validity of the proposed controller to obtain better performance than conventional LQR only controller under the influence of sea current.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2007년도 정기 학술대회 논문집
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• pp.663-668
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• 2007

An enhanced first shear deformation theory for composite plate is developed. The detailed process is as follows. Firstly, the theory is formulated by modifying higher order zigzag theory. That is, the higher order theory is separated into the warping function representing the higher order terms and lower order terms. Secondly, the relationships between higher order zig-zag field and averaged first shear deformation field based on the Reissner-Mindlin's plate theory are derived. Lastly, the effective shear modulus is calculated by minimizing error between higher order energy and first order energy. Then the governing equation of FSDT is solved by substituting shear modulus into effective shear modulus. The recovery processing with the nodal unknown obtained from governing equation is performed. The accuracy of the present proposed theory is demonstrated through numerical examples. The proposed method will serve as a powerful tool in the prediction of laminated composite plate.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2005년도 춘계학술발표대회 개요집
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• pp.384-386
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• 2005

Initial oxide layer on the butt surface fragments during friction stir welding (FSW) and then often remains as a faint zigzag-line pattern on the cross section. When remnant of the oxide layer often adversely affects the mechanical properties in the weld, it is called as 'kissing-bond'. The present study systematically examines effect of oxide array on bend property in the root of friction stir (FS) welded Al alloy 1050 by transmission electron microscopy (TEM), and then clarifies identity of the kissing-bond.