• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 춘계학술대회
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• pp.1083-1088
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• 2003

Molecular dynamics simulations on the deformation behavior of single-walled carbon nanotube are performed. Formation energies of CNT's by interatomic potentials are computed and compared with ab initio results. Bending and axial compression are applied under lattice statics and NVT ensemble conditions. Specifically, we focus on the mechanism of kink formation in bending. The simulation results are comprehensively explained in the framework of atomistic energetics. The effects of temperature and chirality on the deformation of carbon nanotube are also studied.

• Structural Engineering and Mechanics
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• 제50권2호
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• pp.231-240
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• 2014

In the present research, fatigue behavior of chopped strand mat/epoxy composites has been studied with two different techniques. First, the normalized stiffness degradation approach as a well-known model for unidirectional and laminated composites was utilized to predict the fatigue behavior of chopped strand mat/epoxy composites. Then, the capability of the fatigue damage accumulation model for chopped strand mat/epoxy composites was investigated. A series of tests has been performed at different stress levels to evaluate both models with the obtained results. The results of evaluation indicate a better correlation of the normalized stiffness degradation technique with experimental results in comparison with the fatigue damage accumulation model.

• 한국수학사학회지
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• 제33권3호
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• pp.167-177
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• 2020

Cooperative behavior may seem contrary to the notion of natural selection and adaptation, but is widely observed in nature, from the genetic level to the organism. The origin and persistence of cooperative behavior has long been a mystery to scientists studying evolution and ecology. One of the important research topics in the field of evolutionary ecology and behavioral ecology is to find out why cooperation is maintained over time. In this paper we take a historical overview of mathematical models representing cooperative relationships from the perspective of mathematical biology, which studies population dynamics between interacting biological groups, and analyze the mathematical characteristics and meanings of these cooperative models.

• 설비공학논문집
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• 제20권2호
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• pp.137-143
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• 2008

In the present study, a forest fire spread was simulated with a three-dimensional, fully-transient, physics-based, computer simulation program. Physics-based fire simulation is based on the governing equations of fluid dynamics, combustion and heat transfer. The focus of the present study is to perform parametric study to simulate fire spread through flat and inclined wildland with vegetative fuels like trees or grass. The fire simulation was performed in the range of the wind speeds and degrees of inclination. From the results, the effect of the various parameters of the forest fire on the fire spread behavior was analyzed for the future use of the simulation in the prediction of fire behavior in the complex terrain.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집B
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• pp.688-693
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• 2001

It is almost impossible to have a straight web for processing in the continuous process systems. The cambered web usually causes the strip walking and damage during process. It is necessary to identify the lateral dynamics of the cambered web for the precise control of lateral behavior. In this paper, a dynamic model of the lateral behavior for a cambered web is developed by introducing the concept of steering angle equivalent to moment caused by the camber. This model can be extended to include terms associated with moment, induced by roller's tilting, web slippage, and shear force, etc. Using this model, a new feed-forward controller is proposed to enable the on-line camber estimation, which is difficult to be measured directly, and the prediction of lateral deflection caused by camber. Computer simulation study shows that the proposed controller successfully eliminates the effect of camber and has better control performance than that of the existing PID controller.

• Structural Engineering and Mechanics
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• 제56권2호
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• pp.157-167
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• 2015

The impact behavior of epoxy-based nanocomposites reinforced with carbon nano tube (CNT), carbon nano fiber (CNF) and mixed contents of these nanoparticles was investigated using Izod impact test. The results showed that while the impact strength of nanocomposites containing 1 wt% of CNT and 1 wt% of CNF increased 19% and 13% respectively, addition of mixed contents of these nanofillers (0.5-0.5 wt%) demonstrated higher improvement (21%) in the impact resistance. The trend of the results is explained on the basis of different fracture mechanisms of nanocomposites. Furthermore, the fracture surface of specimens and the dispersion state of nanoenhancers have been studied using scanning electron microscopy (SEM) photographs.

• 스마트미디어저널
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• 제13권7호
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• pp.18-26
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• 2024

One of the newest trends in AI is emotion recognition utilizing keystroke dynamics, which leverages biometric data to identify users and assess emotional states. This work offers a comparison of four datasets that are frequently used to research keystroke dynamics: BB-MAS, Buffalo, Clarkson II, and CMU. The datasets contain different types of data, both behavioral and physiological biometric data that was gathered in a range of environments, from controlled labs to real work environments. Considering the benefits and drawbacks of each dataset, paying particular attention to how well it can be used for tasks like emotion recognition and behavioral analysis. Our findings demonstrate how user attributes, task circumstances, and ambient elements affect typing behavior. This comparative analysis aims to guide future research and development of applications for emotion detection and biometrics, emphasizing the importance of collecting diverse data and the possibility of integrating keystroke dynamics with other biometric measurements.

• 한국시스템다이내믹스연구
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• 제3권2호
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• pp.113-140
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• 2002

The cost-benefit analysis is a technique for assisting with decision about the use of society's scare resources. There exists no detailed assessment like cost-benefit analysis. But recently, many policy analysts criticized the merit of cost-benefit analysis. As it is, it can be said that partial or approximate estimates of benefit and cost may be more dangerous than helpful. The purpose of this study is to overcome the limit of traditional cost-benefit analysis. For this purpose, we use the system dynamics approach for setting up new cost-benefit analysis, which we named that ‘Dynamics Cost-Benefit Analysis'. The usefulness of ‘Dynamics Cost-Benefit Analysis' is as follows; finding structural causal relationship between cost factors and benefit factors, understanding the long-term behavior of systems economic feasibility. In this study, we apply 'Dynamic Cost-Benefit Analysis' to case that is construction investment of funeral house by local government sector.

• BMB Reports
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• 제34권1호
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• pp.1-7
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• 2001

Structural and physical properties of type wild type and various selected mutants of the vnd/NK-2 homeodomain, the protein product of the homeobox, and the implication in genetic disease are reviewed. The structure, dynamics and thermodynamics have been Investigated by NMR and by calorimetry. The interactions responsible for the nucleotide sequence-specific binding of the homeodomain to its consensus DNA binding site have been identified. There is a strong correlation between significant structural alterations within the homeodomain or its DNA complex and the appearance of genetic disease. Mutations in positions known to be important in genetic disease have been examined carefully For example, mutation of position 52 of vnd/NK-2 results in a significant structural modification and mutation of position 54 alters the DNA binding specificity and amity The $^{15}N$ relaxation behavior and heteronuclear Overhauser effect data was used to characterize and describe the protein backbone dynamics. These studies were carried out on the wild type and the double mutant proteins both in the free and in the DNA bound states. Finally, the thermodynamic properties associated with DNA binding are described for the vnd/NK-2 homeodomain. These thermodynamic measurements reinforce the hypothesis that water structure around a protein and around DNA significantly contribute to the protein-DNA binding behavior. The results, taken together, demonstrate that structure and dynamic studies of proteins combined with thermodynamic measurements provide a significantly more complete picture of the solution behavior than the individual studies.

• Tribology and Lubricants
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• 제32권1호
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• pp.9-17
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• 2016

Contact between solid surfaces is one of the most important factors that influence dynamic behavior in micro/nanoscale. Although numerous theories and experimental results on contact behavior have been proposed, a thorough investigation for nanomaterials is still not available owing to technical difficulties. Therefore, molecular dynamics simulation was performed to investigate the contact behavior of nanomaterials, and the application of conventional contact theories to nanoscale was assessed in this work. Particularly, the contact characteristics of cylindrical nanowires were examined via simulation and contact theories. For theoretical analysis, various contact models were utilized and work of adhesion, Hamaker constant and elastic modulus those are required for calculation of the models were obtained from both indentation simulation and tensile simulation. The contact area of the cylindrical nanowire was assessed directly through molecular dynamics simulation and compared with the results obtained from the theories. Determination of the contact area of the nanowires was carried out via simulation by counting each atom, which is within the equilibrium length. The results of the simulation and theoretical calculations were compared, and it was estimated that the discrepancy in the results calculated between the simulation and the theories was less than 10 except in the case of the smallest nanowires. As the result, it was revealed that contact models can be effectively utilized to assess the contact area of nanomaterials.