• 대한화학회지
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• 제34권2호
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• pp.130-135
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• 1990

Z-3-파라-톨리치오-4-니트로-3-헥센의 결정은 단사정계에 속하며 a = 13.756 (3), b = 9.310(4), c = 21.305(3) $\AA$, $\beta = 95.0_{\circ}$이며 단위세포안에 8개의 분자가 있으며 2.0$\sigma$(I) 보다 큰 강도를 가진 2935개의 회절반점에 대하여 계단식 대각 최서자승법에 의하여 정밀화된 최종 R값은 0.085이다. 직접법에 의하여 구조를 풀었으며 C-H결합길이와 메칠기는 길이를 고정시켜 이상적인 기하학적구조에 맞도록 하여 계산을 정밀화하였다. 두 분자 A와 B는 끝의 두 에칠기를 제외하고는 거의 유사한 구조를 갖고 있다. 니트로기를 포함한 에틸렌 모양의 골격은 메칠벤젠기에 거의 수직으로 되어 있으며 두 에틸기는 시스-형 구조를 가지고 있으나 끝부분의 메칠기는 A분자에서는 그의 골격에 대해 서로 반대방향으로 향하고 있고 B분자는 같은 방향으로 향하고 있다. 결정내 분자들은 비결합성 van der Waals힘으로 쌓여져 있다.

• Composites Research
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• 제23권3호
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• pp.13-18
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• 2010

나노 재료를 다룰 때 큰 문제 중의 하나는 반데르발스(van der Waals) 상호작용으로 응집되어 있는 나노 입자, 특히 CNT를 어떻게 효과적으로 분산시킬 수 있는가이다. 본 연구에서는 나노 입자를 효과적으로 분산시킬 수 있는 방법으로 코로나 방전(corona discharge) 현상과 정전식모(electrostatic flocking) 공정을 이용한 새로운 분산방법인 방전식모(dischare flocking) 장치를 고안하였으며 분산특성을 평가하기 위하여 방전식모 및 RFI 공정으로 복합재료 시편을 제작하여 전기적, 기계적 특성을 비교하였다. 더욱이, CNT와 에폭시의 기체 방전 효과를 평가하기 위하여 플라즈마 처리된 CNT를 사용하여 복합재료를 제작하였으며 전기적, 기계적 특성을 측정하였다. 방전식모 공정으로 제작 된 복합재료 시편의 특성은 RFI로 제작된 시편과 유사하였으며 방전식모 공정중의 기체방전 현상은 플라즈마 처리된 CNT에 영향을 주지 않았다.

• 대한화학회지
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• 제34권1호
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• pp.1-9
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• 1990

콜레스테릴 펜타노에이트의 결정은 사방정계에 속하며 a = 21.930(3), b = 21.404(3), c = 6.419(5) $\AA$이며 단위세포안에 4개의 분자가 있다. 1.0 $\sigma$ (I)보다 큰 강도를 가진 1,520개의 회절 반점에 대한 최종 R값은 0.086이다. 직접법에 의하여 구조를 풀었으며 C-H 결합길이와 메틸기는 길이를 고정시켜 이상적인 기하학적 구조에 맞춰 cascade diagonal least-squares refinement에 의하여 정밀화하였다. 테트라시클로 고리는 정상적인 구조를 하고 있으나 에스텔과 곁사슬 부분은 열적효과에 의하여 정상적인 길이와 각도의 값에서 변화를 보이고 있으며 에스텔의 끝부분이 굽어져 치켜들고 있다. 분자는 비결합성 van der waals힘에 의하여 서로 쌓여져 있고 가장 짧은 분자간 거리는 3.529 $\AA$이다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.1542-1546
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• 2003

Nanotechnology is an important challenge, for which nanoparticle manipulation plays an important role in the assembly of nano elements. In this study, the dynamic equation of system plant is established by van der Waals force, friction, capillary forces etc. To push nanoparticles, strain gauges are used as sensors to actuate an X-Y stage in an atomic force microscopy system. A strategy of pushing nanoparticles is developed based on sliding mode control. Moreover, afuzzy controller is responsible for compensating tip-particle contact loss according to feedback signals of a laser-detector system. According to position control result, experimental results of gold nanoparticle manipulation are presented.

• 한국환경과학회지
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• 제27권10호
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• pp.901-906
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• 2018

Water and oxygen are two of the most essential molecules for many species on earth. Their unique properties have been studied in many areas of science. In this study, the interaction of water and oxygen molecules was observed at the nano-scale. Using molecular dynamics, a water droplet with 30,968 water molecules was simulated. Then, 501 oxygen molecules were introduced into the domain. A few oxygen molecules were attracted to the surface of the water droplet due to van der Waals forces, and some oxygen molecules actually entered the water droplet. These interactions were visualized and quantified at four temperatures ranging from 280 to 370 K. It was found that at high temperatures, there was a higher possibility of the oxygen molecules penetrating the water droplet than that at lower temperatures. However, at lower temperatures, oxygen molecules were more likely to be found interacting at the surface of the water droplet than at high temperatures.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 추계학술대회
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• pp.410-415
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• 2004

Molecular dynamics simulations of nanoimprint lithography in which a stamp with patterns is pressed onto amorphous poly-(methylmethacrylate) (PMMA) surface are performed to study the deformation of polymer. Force fields including bond, angle, torsion, inversion, van der Waals and electrostatic potential are used to describe the intermolecular and intramolecular force of PMMA molecules and stamp. Periodic boundary condition is used in horizontal direction and $Nos\acute{e}$-Hoover thermostat is used to control the system temperature. As the simulation results, the adhesion forces between stamp and polymer are calculated and the mechanism of deformation are investigated. The effects of the adhesion force and friction force on the polymer deformation are also studied to analyze the pattern transfer in nanoimprint lithography. The mechanism of polymer deformation is investigated by means of inspecting the indentation process, molecular configurational properties, and molecular configurational energies.

• 한국소음진동공학회논문집
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• 제20권6호
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• pp.593-603
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• 2010

In this paper, vibration and flow-induced flutter instability analysis of cantilever multi-wall carbon nanotubes conveying fluid and modelled as a thin-walled beam is investigated. Non-classical effects of transverse shear and rotary inertia and van der Waals forces between two walls are incorporated in this study. The governing equations and the associated boundary conditions are derived through Hamilton's principle. Numerical analysis is performed by using extend Galerkin method which enables us to obtain more exact solutions compared with conventional Galerkin method. Cantilevered carbon nanotubes are damped with decaying amplitude for flow velocity below a certain critical value, however, beyond this critical flow velocity, flutter instability may occur. Variations of critical flow velocity with both radius ratio and length of carbon nanotubes are investigated and pertinent conclusion is outlined.

• Bulletin of the Korean Chemical Society
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• 제28권3호
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• pp.421-426
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• 2007

A linking ligand containing sulfur donor atoms in the terminal thiophene rings, 1,2-bis(thiophen-2-ylmethylene) hydrazine (L), was prepared by Schiff-base condensation. Ligand L reacted with [PdCl2(NCPh)2] to produce a molecular Pd compound [PdL2Cl2] (1). On the other hand, it reacted with AgNO3 and AgClO4 to produce a 2-D network [AgL0.5(NO3)] (2) and a 1-D polymer [AgL]ClO4 (3), respectively, whose structures are based on secondary intermolecular forces such as H-bonding, van der Waals interaction, and π-π stacking. Polymer 2 exhibited photoluminescence at room temperature in the solid state.

• Archives of Pharmacal Research
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• 제14권1호
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• pp.1-6
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• 1991

The crystal structure of licarin-B, a component of Myristicae Semen was determined by single crystal X-ray diffraction analysis. Crystal of the compound, which was recrystallized from the mixture of hexane and ether, is monoclinic with a=12.740(1), b=7.219(1), c=9.284(1) ${\AA}$, ${\beta}=94.75(1)^{\circ}$, $D_x=1.26$, $D_m=1.27\;g/cm^3$, space group P21, and Z=2. The structure was solved by direct method and refined by least-squares procedure to the final R value of 0.040 for 1532 independent reflections ${F{\ge}3{\sigma}(F)}$. The compound is a dimeric phenylpropanoid, and belongs to the neolignan analogues. The molecules are arranged along with the screw axis. The intermolecular contacts appear to be the normal van der Waals' forces.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 춘계학술대회논문집
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• pp.73-76
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• 2004

Tapping mode atomic force microscopy (TM-AFM) utilizes the dynamic response of a resonating probe tip as it approaches and retracts from a sample to measure the topography and material properties of a nanostructure. We present recent results based on numerical techniques that yield new perspectives and insight into AFM. It is compared that the dynamic models including van der Waals and Derjaguin-Muller-Toporov(DMT) or Johnson-Kendall-Roberts(JKR) contact forces demonstrates that periodic solutions can be represented with respect to the approach distance and excitation frequency.