• Interaction and multiscale mechanics
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• 제4권4호
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• pp.247-255
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• 2011

Understanding the structural stability of carbon nanostructure under heat treatment is critical for tailoring the thermal properties of carbon-based material at small length scales. We investigate the heat resistance of the single carbon nanoball ($C_{60}$) and carbon nanoonions ($C_{20}@C_{80}$, $C_{20}@C_{80}@C_{180}$, $C_{20}@C_{80}@C_{180}C_{320}$) by performing molecular dynamics simulations. An empirical many-body potential function, Tersoff potential, for carbon is employed to calculate the interaction force among carbon atoms. Simulation results shows that carbon nanoonions are less resistive against heat treatment than single carbon nanoballs. Single carbon nanoballs such $C_{60}$ can resist heat treatment up to 5600 K, however, carbon nanoonions break down after 5100 K. This intriguing result offers insights into understanding the thermal-mechanical coupling phenomena of nanodevices and the complex process of fullerenes' formation.

• 한국시스템다이내믹스연구
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• 제7권2호
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• pp.149-170
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• 2006

In this paper, an energy-economy-environment dynamic simulation model was developed to using system dynamics methodology. It describes current energy-economy-environment systems and forecasts changes caused by levying of carbon tax. The model is composed of three modules: an energy module, an economic module and an environmental module. Variables are interrelated in each module, and three modules are linked by several linkage variables. Setting up the linkage variables is an important factor for the composition of the model. The simulation result shows a change of the national GDP, usage of energy, and $CO_2$ emissions under levying and reinvestment of carbon tax considering various scenarios for the charging cost.

• Bulletin of the Korean Chemical Society
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• 제33권3호
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• pp.893-896
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• 2012

Using molecular dynamics simulation method, we studied the carbon nanotube (CNT) non-covalently interacting with a polymer. As the polymer coiled around the CNT, the diameter of CNT deformed by more than 40% of its original value within 50 ps. By considering three different polymers, we conclude that the interaction between the CNT and polymer is governed by the number of repeating units in the polymer, not by the molecular weight of polymer.

• 한국조경학회지
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• 제45권2호
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• pp.11-22
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• 2017

저탄소 도시 실현의 대안으로써 저탄소경관을 창출하기 위해서는 다중 스케일 차원에서 디자인 요소들의 동태성을 이해해야 하며, 탄소 저장효과를 정량적으로 평가할 수 있어야 한다. 본 연구의 목적은 시스템 다이내믹스를 활용하여 인공지반 교목의 탄소저장량 변화를 장기적인 측면에서 시뮬레이션하고 평가하는 것이다. 연구의 과정은 인과지도를 통해 다중 스케일 측면에서 탄소순환의 동태성을 분석하고, 강남구청 본관 옥상공원의 탄소저장량에 대하여 2008년, 2018년, 2028년, 2038년의 변화를 시뮬레이션하였다. 연구의 결과는 다음과 같다. 첫째, 인공지반 교목과 도시 탄소순환 탄소저장량의 관계에 대한 인과지도 분석결과, 다중 스케일간의 관계성이 확인되었다. 둘째, 시뮬레이션 모델의 주요변수는 '바이오매스', '탄소저장량', '고사유기물', '탄소흡수량'이 선정되어 모델에 활용되었으며, 적합도는 $R^2=0.725$(p<0.05)로 유의한 것으로 나타났다. 셋째, 시뮬레이션 모델 결과, 인공지반 교목의 탄소저장량은 시간의 흐름에 따라 수종의 순위가 다양하게 변하였다. 이에 따라 본 연구에서는 홍단풍, 소나무, 자작나무와 같은 수종을 강남구청 본관 옥상공원의 탄소저장량 향상을 위한 수종으로 제안하였다. 이러한 연구 결과는 저탄소경관 계획 시 식재계획의 기준안 또는 수종 선택에 기여할 수 있을 것이다.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2003년도 추계학술대회논문집
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• pp.347-354
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• 2003

The dynamics of fluid flow through nanomachines is completely different from that of continuum. In this study, molecular dynamics simulations were performed for the flow of helium, neon, argon inside carbon(graphite) nanotubes of several sizes. The fluid was introduced into the nanotube at a given initial velocity according to given temperature. Diffusion coefficients were evaluated by Green-Kubo equation derived from Einstein relationship. The behaviour of the fluid was strongly dependent on the density of fluid and tube diameter, not on the tube length. It was found that the diffusion Coefficients increased With decreasing the density of molecules and increasing the diameter and temperature.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2007년도 추계학술대회 논문집
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• pp.348-351
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• 2007

Simulations of the buckling behavior of a single wall carbon nanotube(SWCNT) was carried out using molecular dynamics simulation. Molecular dynamics simulations were done with 1fs of time step. Tersoff's potential function was used as the interatomic potential function since it has been proved to be reliable to describe the C-C bonds in carbon nanotubes. Compressive force was applied by moving the top end of the nanotube at a constant velocity. Buckling behavior under compressive load was observed for (15,15) armchair SWCNTs with 2nm of diameter and 24.9nm of length. Buckling load and critical strain is obtained from the MD simulation. Deformation occurred on the top region of the CNT because of fast downward velocity.

• Bulletin of the Korean Chemical Society
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• 제23권8호
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• pp.1163-1165
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• 2002

• 반도체디스플레이기술학회지
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• 제8권4호
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• pp.21-24
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• 2009

We investigated a nanoscale inertia sensor based on telescoping carbon nanotubes, using classical molecular dynamics simulations. The position of the telescoping nanotubes is controlled by the centrifugal force exerted by the rotation platform, thus, position shifts are determined by the capacitance between carbon nanotubes and the electrode, and the operating frequency of the carbon nanotube oscillator. This measurement system, tracking oscillations of the carbon nanotube oscillator, can be used as the sensor for numerous types of devices, such as motion detectors, accelerometers and acoustic sensors.

• 한국전기전자재료학회논문지
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• 제17권8호
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• pp.812-822
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• 2004

This paper shows that carbon nanotubes can be applied to a nanopipette. Nano space in atomic force microscope multi-wall carbon nanotube tips is filled with molecules and atoms with charges and then, the tips can be applied to nanopipette when the encapsulated media flow off under applying electrostatic forces. Since the nano space inside the tips can be refilled, the tips can be permanently used in ideal conditions of no chemical reaction and no mechanical deformation. Molecular dynamics simulations for nanopipette applications demonstrated the possibility of nano-lithography or single-metallofullerene-transistor array fabrication.

• Coupled systems mechanics
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• 제3권4호
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• pp.329-344
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• 2014

In this work, quantum molecular dynamics simulations (QMD) are preformed to study the hydrogen molecules in three types of carbon nanostructures, $C_{60}$ fullerene, (5,5) and (9,0) carbon nanotubes and graphene layers. Interactions between hydrogen and the nanostructures is of importance to understand hydrogen storage for the development of hydrogen economy. The QMD method overcomes the difficulties with empirical interatomic potentials to model the interaction among hydrogen and carbon atoms in the confined geometry. In QMD, the interatomic forces are calculated by solving the Schrodinger's equation with the density functional theory (DFT) formulation, and the positions of the atomic nucleus are calculated with the Newton's second law in accordance with the Born-Oppenheimer approximation. It is found that the number of hydrogen atoms that is less than 58 can be stored in the $C_{60}$ fullerene. With larger carbon fullerenes, more hydrogen may be stored. For hydrogen molecules passing though the fullerene, a particular orientation is required to obtain least energy barrier. For carbon nanotubes and graphene, adsorption may adhere hydrogen atoms to carbon atoms. In addition, hydrogen molecules can also be stored inside the nanotubes or between the adjacent layers in graphite, multi-layer graphene.