• Korean System Dynamics Review
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• v.9 no.1
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• pp.57-71
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• 2008

This research paper describes a complex and vague settings in which organization makes a decision and explains a role of decision maker's learning process. The original paper, written by Cohen, March, Olsen in 1972, said that all members of organization depended on the technology taken through trials and errors, which is the 'learning' process literally. But they intended to exclude the learning process in their simulation model because their PORTRAN model couldn't replicate the learning concept. As a result, they couldn't explain how all agents of garbage can simulation model resolve the problem dynamically. To overcome this original paper's limitations, we try to rebuild a learning process simulation model using by system dynamics approach that can capture the linkage between organization leanings and agents-based decision-makings. Our learning simulation results reveal two points. First, decision maker's leanings process improves the efficiency of decision making in complex situation. Second, group learning shows a superior efficiency to an individual learning because group members share organizational memory and energy.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.8 no.1
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• pp.43-47
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• 2009

Recently, an approach for nano-scale material deformation has been developed that couples the atomistic and continuum approaches using Finite Element Method (FEM) and Molecular Dynamics (MD). However, this approach still has problems to connect two approaches because of the difference of basic assumptions, continuum and atomistic modeling. To solve this problem, an alternative way is developed that connects the QuasiMolecular Dynamics (QMD) and molecular dynamics. In this paper, we suggest the way to make and validate the MD-QMD coupled model.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.343-348
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• 2007

Molecular dynamics study of thermal NIL (Nano Imprint Lithography) process is performed to examine stamp-resist interactions. A layered structure consists of Ni stamp, poly-(methylmethacrylate) thin film resist and Si substrate was constructed for isothermal ensemble simulations. Imposing confined periodicity to the layered unit-cell, sequential movement of stamp followed by NVT simulation was implemented in accordance with the real NIL process. Both vdW and electrostatic potentials were considered in all non-bond interactions and resultant interaction energy between stamp and PMMA resist was monitored during stamping and releasing procedures. As a result, the stamp-resist interaction energy shows repulsive and adhesive characteristics in indentation and release respectively and irregular atomic concentration near the patterned layer were observed. Also, the spring back and rearrangement of PMMA molecules were analyzed in releasing process.

• Korean Management Science Review
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• v.23 no.1
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• pp.87-113
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• 2006

This paper describes a comprehensive approach to examine how technological innovation contributes to the renewal of the firm's competences through its dynamic and reciprocal relationship with R&D and product commercialization. Three theories of technology and innovation (R&D and technological knowledge concept, product-process concept, technological interdependence concept) are used to relate technology and innovation to strategic management. Based on those theories, this paper attempts to identify dynamic relationship between product innovation and process innovation by system dynamics, by investigating the aspect of the dynamic changes of the closed feedback circulation structure in which R&D investments drive technological knowledge accumulation, and such knowledge accumulation actualizes product innovation and process innovation, subsequently resulting in the increase of productivity, customer satisfaction, profit generation, and re-investment on R&D from the created profits. This provides the ability to assess the advantages and disadvantages of different technological innovation strategies and commitments, and the opportunity to explore equilibrium point and suggest a generalized technological innovation model under different industry environment parameters and time-strategies.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.15 no.4
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• pp.162-167
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• 2005

As the properties of porous materials during the drying process relate to the atomistic defects of heterogeneous materials such as dislocation, grain, grain boundary, pore, etc., the knowledge of nano-scale analysis is needed in order to accurately analyze the drying process for porous materials. In this study, the atomic behavior of porous materials Is statically predicted by using the molecular dynamics simulation and the nano-scale material properties are computed. The elastic modulus, thermal expansion coefficient, and volumetric heat capacity numerically found from the molecular dynamics simulation are compared with those of experiment and theory and proved the accuracy.

• Tribology and Lubricants
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• v.22 no.5
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• pp.243-251
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• 2006

Molecular dynamics simulations of nanoimprint lithography NIL) are performed in order to investigate effects of process parameters, such as stamp shape, imprinting temperature and adhesive energy, on nanoimprint lithography process and pattern transfer. The simulation model consists of an amorphous $SiO_{2}$ stamp with line pattern, an amorphous poly-(methylmethacrylate) (PMMA) film and an Si substrate under periodic boundary condition in horizontal direction to represent a real NIL process imprinting long line patterns. The pattern transfer behavior and its related phenomena are investigated by analyzing polymer deformation characteristics, stress distribution and imprinting force. In addition, their dependency on the process parameters are also discussed by varying stamp pattern shapes, adhesive energy between stamp and polymer film, and imprinting temperature. Simulation results indicate that triangular pattern has advantages of low imprinting force, small elastic recovery after separation, and low pattern failure. Adhesive energy between surface is found to be critical to successful pattern transfer without pattern failure. Finally, high imprinting temperature above glass transition temperature reduces the imprinting force.

• Transactions of the Korean Society of Mechanical Engineers
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• v.5 no.4
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• pp.303-311
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• 1981

Machine tool dynamics is investigated under actual working conditions. Experimental evaluation of cutting dynamics in a lathe is made with cutting conditions and cutting positions varied. The thrust force and the toolpost and tailstock accelerations during turning process are modelled and analyzed by employing Dynamic Data System methodology. It is found that two acceleration signals are good enough to replace the thrust force, when used for machine tool identification under cutting process and for chatter detection.

• Korean System Dynamics Review
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• v.5 no.2
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• pp.33-66
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• 2004

This study is an exploratory investigation on how national R&D investments decisions are made in Korea. For developing system dynamic model, we are interested in locating three structural dilemma, occurring with the Korean NIS. In so doing, we intend to devise the ways of ameliorating problems within the NIS investment decision-making process by providing policy implications. We identify delays and side effects during transition periods between different stages of technology innovation by perceiving the switching pattern dynamically, in which form of technologies shifts from one to another stage like paradigm shift, when the R&D investment reaches a certain stock. It is also suggested that the development of strategies is necessary in order to enhance efficiency of technological development process.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.2 s.95
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• pp.104-115
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• 1999

Cutting process, in general, is a closed-loop system consisting of structural dynamics and cutting dynamics, with the cutting forces and the relative displacements between tool and workpiece being the associated variables. There have been a number of works on modeling the cutting process of endmilling, most of which assumed that either one of the tool or workpiece be negligible in tis displacement. In this paper, the relative displacement between tool and workpiece was considered. The proposed model used experimental modal analysis for structural dynamics and an instantaneous uncut chip thickness model for cutting dynamics. Simulation of the model, a time varying cutting system, was performed using 4th order Runge-Kutta method. Subsequent simulation results were utilized to predict chatter over a variety of experiments in slotting operation, showing good agreement.

• Korean System Dynamics Review
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• v.12 no.1
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• pp.59-74
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• 2011

This article deals with an economic evalutation of the 'Pasture Project of Kum River', which is the farming plan of mitten crabs in a stream of it. An augmented model of social capital is based on the past ecological-economic system dynamics model and elaborated further with suggestions of social capital literature. During the modeling process a chain diagram of causal relations and its relevant mathematical equations are presented for simulating the project performance, and the simulation results are provided to contrast the dynamic behaviors of the former ecological-economic model with ones of the new model incorporating social capital. The results indicate that an increase in the economic benefit of the project could happen in case of considering the process of social capital accumulation around the case area, which can be regarded as a remarkable trial to approve the common confidence in the role of social capital to enhance an economic achievement.