• Korean System Dynamics Review
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• v.3 no.1
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• pp.61-77
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• 2002

This paper reviews issues and methodological status of system dynamics and suggest some research agenda for its development in Korea. After reviewing some characteristics of system dynamics approach, including dynamic feedback perspective and endogenous point of view, the paper pointed out methodological characteristics of system dynamics. It seems to be the most notable characteristics of System Dynamics that it use both quantitative and qualitative approach in explaining and modelling reality. Besides, System Dynamicists rely more heavily on refutationism than instrumentalism and this allows System Dynamicists follow more strict way of scientific inquiry. For the development of System Dynamics in Korean academic circle, developing training program and curriculum, networking scattered System Dynamicist all over the country, would be the most important task.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.409-414
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• 2007

Nowadays, with the advancement of computational mechanics, and vehicle dynamics simulation linked up with virtual testing laboratory(VTL) and virtual proving ground(VPG) technologies has become a useful method for analyzing numerous driving performances and diverse noise/vibration characteristics. In this paper, the analytical vehicle model based on multi-body dynamics theory was developed to investigate the vibration characteristics according to various road conditions. For the purpose, the whole vehicle parameters, each vehicle's part parameter, and part connecting elements such as spring, damper, and bush were measured by an experiment. Also, the vehicle dynamics model, which includes the front suspension, rear suspension, steering, front wheel, rear wheel, and body subsystems has been constructed for computer simulation. With the developed vehicle dynamics model, three forces and three moments measured at each wheel center were applied to evaluate and analyze dynamics and vibration characteristics for miscellaneous road conditions.

• Journal of Korea Planning Association
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• v.54 no.3
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• pp.75-90
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• 2019

As the 24-hour society arrives, human activities in daytime and nighttime urban spaces are changing drastically, and the need for new urban management policies is steadily increasing. This study analyzes the types and characteristics of Seoul's human dynamics using location-based big data and the results are summarized as follows. First, the pattern of human dynamics in Seoul repeats itself every 7 days. Second, the types of human dynamics in Seoul can be classified into five types, and each of type has its own unique time-series and local characteristics. Third, the degree of match between human dynamics and zoning system in urban planning legislation was highest in 'Type 1' residence pattern and low in other types. The following implications can be drawn from these results. First, This paper examined the methodology of analyzing the regional characteristics of Seoul through the human dynamics and obtained meaningful results. Second, This paper can derive reliable and objective pattern analysis results using Big data that reflect the overall population characteristics. Third, the scale of night-time activity in the urban space of Seoul was understood, and its distribution, patterns and characteristics identified.

• Korean System Dynamics Review
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• v.11 no.2
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• pp.5-28
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• 2010

The purpose of this paper is to review relationship between spatial characteristics of compact city and urban sustainabiliy from system dynamics perspective using causal loop analysis. It has been argued that spatial characteristics of compact city, high population density and mixed land use, are positively related to urban sustainability. However, research results that are not consistent with pros of compact city argument have been accumulated too. It is especially true when spatial characteristics of compact city are examined with regard to each dimension of sustainablility: economic, social, and environmental sustainability. Reviewing each dimension of sustainability with regard to spatial characteristics based on causal loop analysis, this paper provides more clear understanding on relationship between compact city and sustainability. Also this paper provides a base for system dynamics simulation for future study.

• Journal of the Korea Institute of Military Science and Technology
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• v.25 no.2
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• pp.196-209
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• 2022

Driving dynamic characteristics of semi-trailer loaded with precise equipments are very important to protect them from vibration, impact or other disturbances. In this paper, in order to identify the driving dynamic characteristics of the large scale semi-trailer equipped with swivel axle and hydropneumatic suspension unit, Dynamics Modeling & Simulation(M&S) were performed using general Dynamics Analysis Program(RecurDyn V9R2). The semi-trailer was modeled as two types - one is Multi Rigid Body Dynamics(MRBD) model, and the other Rigid-Flexible Body Dynamics(RFlex) one. The natural vibration mode and frequencies of semi-trailer body, acceleration of dummy-weight, pitch, roll and yaw of dummy-weight, swivel axle and hydropneumatic suspension cylinder support structure, and acting force of hydropneumatic suspensions etc. were obtained from the M&S. Additionally frequency analysis were performed using the data of behavior obtained from above M&S. Generally the quantitative results of RFlex are larger than them of MRBD in view of magnitude of the comparable parametric values.

• Journal of Power System Engineering
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• v.7 no.3
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• pp.61-68
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• 2003

Steering characteristics is an important factor in the evaluation of vehicle quality. To estimate steering characteristics in the vehicle conceptual design stage, vehicle dynamics simulation methods are very efficient. However, it is often difficult to simulate vehicle dynamics for the specific driving scenarios in open-loop driving environment. An efficient driver-in-the-loop vehicle model will be efficient for this job. A good tire model is also very important for the accurate vehicle dynamics simulation. In this research, a driver model is used to simulate vehicle steering dynamics for a 8-dof vehicle model with STI(Systems Technology, Inc.) tire model. For the demonstration of this model, a SUV(sports utility vehicle) and a sedan were simulated.

• 제어로봇시스템학회:학술대회논문집
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• 1993.10a
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• pp.1172-1177
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• 1993

Dynamic characteristics of a hydraulic power supply are studied theoretically and computationally. The transfer function between the supply pressure and the load flow is derived considering relief valve dynamics, accumulator dynamics, and flow line dynamics. Frequency responses and time responses are obtained in many conditions using the transfer function and nonlinear mathematical model respectively.

• Korean System Dynamics Review
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• v.17 no.3
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• pp.31-50
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• 2016

This study examines the basic conditions of joint authorship research activities in the Korean System Dynamics Review and points out the structural co-author network characteristics among co-authored papers based on the social network analysis(SNA) techniques. In specific, this study identifies the cooperative relationship of research papers in the Korean System Dynamics Review, knowledge formation, and knowledge propagation paths. The study results imply that Korean System Dynamics Review has exhibited the typical 'Steven's power law,' which is repeatedly observed among complex systems, and that knowledge structure centered upon and propagated around couples of researchers. Additionally, the study results present that there have been active personal exchanges among major researchers. In contrast, personal contacts among research groups and within groups seem relatively weak.

• Journal of the Korean Physical Society
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• v.73 no.9
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• pp.1385-1392
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• 2018

A network with coupled biological neurons provides various forms of collective synchronous dynamics. Such phase-locking dynamics states resemble eigenvectors in a linear coupling system in that the forms are determined by the symmetry of the coupling strengths. However, the states behave as attractors in a nonlinear dynamics system. We here study the collective synchronous dynamics in a neural system by using a novel theory. We exhibit how the period and the stability of individual phase-locking dynamics states are determined by the characteristics of synaptic couplings. We find that, contrary to common sense, the firing rate of a synchronized state decreases with increasing synaptic coupling strength.

• Journal of the Korea Institute of Military Science and Technology
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• v.22 no.5
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• pp.687-696
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• 2019

To identify the driving dynamic characteristics of the Tractor-Trailer Type Transporter for mounting a large scale precision equipment, real vehicle driving tests on the 3 inch-bump-space-road were performed. And using general Dynamics Analysis Program - RecurDyn(V8R5), Dynamics M&S were carried out assuming the similar condition with real tests. Then the acceleration data obtained from real tests and M&S were analyzed and compared with each other in the part of root-mean-square-acceleration($g_{rms}$), peak-acceleration($g_{peak}$) and frequencies. In simple view of the $g_{rms}$ & $g_{peak}$, although the results of MRBD are more similar to ones of the real vehicle driving tests, but the results of RFlex have more information to get various useful dynamic characteristics.