• Korean System Dynamics Review
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• v.8 no.2
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• pp.51-82
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• 2007

The purpose of this paper is exploring changes in land use pattern when considering environmental carrying capacity. A sustainable development requires a society to define sustainability constraints, environmental carrying capacity. Environmental carrying capacity can be defined as a level of human activity a region can sustain at a desired level of quality of environment. This concept of environmental carrying capacity can be applied to land use to explore sustainable land use pattern. Since land use pattern can affect environment in an important way, exploring sustainable land use pattern within the limit of environmental carrying capacity can suggest useful implications for a sustainable regional management and planning. For this purpose, this paper built the environmental carrying capacity land use model and applied it to the Metropolitan Area, Korea. System dynamics modeling methods was used to build the model. The model developed in this paper consisted of 6sectors; population, housing, industry, land, environment, and traffic sector. The model limits its main focus on the NO2 level as an indicator of quality of environment in Metropolitan Area. Box model was translated into system dynamics model and combined to urban dynamics model to estimate NO2 level, the maximum number of population, industry structure, housing and maximum amount of land use for industrial, housing, and green space that can sustain desirable NO2 level. Metropolitan area was divided into 16 areas and the model was applied to each area. Since NO2 is flowing in and out from each area, model was built to allow this transboundering nature of air pollutants. Based on the model estimation, several policy implications for a sustainable land use pattern was discussed.

• Proceedings of the KSR Conference
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• 2006.11a
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• pp.229-238
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• 2006

In general, the Maglev vehicle is run over an elevated guideway consisting of steel or concrete structure. Since the running behavior of the vehicle is affected by the flexibility of the guideway, the consideration of the flexibility of guideway is needed for evaluating the dynamics of both the vehicle and guideway. A new method based on flexible multibody dynamics is proposed to model the Maglew vehicle. This method combines the levitation controller, vehicle, and guideway into a coupled model To verify the method, an urban transit is analyzed using the method and discussions are carried out.

• Proceedings of the Korea Water Resources Association Conference
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• 2019.05a
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• pp.267-267
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• 2019

Driftwood is one of serious problems in a river environment. In several countries, such as Indonesia, Japan, and Italy, the driftwood frequently appears in a river basin, and it can alter the channel bed, flow configuration by wood deposition and jam formation. Therefore, the studies related to driftwood have been actively conducted by many researchers to understand the mechanism of driftwood dynamics. In particular, wood motion by collision is one of the difficult issues in the numerical simulation because the calculation for wood collision requires significantly expensive calculation time due to small time step. Thus, this study conducted the numerical simulation in consideration of the wood motion by water flow and wood collision to understand the wood dynamics in terms of computation. We used the 2D (two-dimensional) depth-averaged velocity model, Nays2DH, which is a Eulerian model to calculate the water flow on the generalized coordinate. A Lagrangian type driftwood model, which expresses the driftwood as connected sphere shape particles, was employed to Nays2DH. In addition, the present study considered root wad effect by using larger diameter for a particle at a head of driftwood. An anisotropic bed friction was considered for the sliding motion dependent on stemwise, streamwise and motion directions. We particularly considered changeable draft at each particle and projection area by an angle between stemwise and flow directions to precisely reproduce the wood motions. The simulation results were compared with experimental results to verify the model. As a result, the simulation results showed good agreement with experimental results. Through this study, it would be expected that this model is a useful tool to predict the driftwood effect in the river flow.

• Korean System Dynamics Review
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• v.13 no.2
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• pp.25-45
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• 2012

The purpose of this study is to estimate the effects of healthy city policies on residents' walking. In order to estimate promotion of walking rates by healthy cities policies, it developed System dynamics(SD)-based model which showed causal relationships among urban design, public health policies, and walking levels. SD technique is useful for future forecast and policy impact assessment. The spatial units of the SD-based system for policy impact assessment included 66 cities, counties, and communities in Seoul Metropolitan Area. The system simulation was planned to be run for 21 years from 2009 to 2030. For this study, 3 alternatives were proposed with combinations of length of bike lanes, number of bus routes, crime rates, self-reported good health status rates, and obesity rates. As a result of simulations, residents' participation rates for walking were increased from 1.00% to 9.98%. This study contributes to better understanding the benefits of healthy cities that are associated with individual walking. It further provided useful insights into planners' role in promoting health. The paper concluded with a discussion on future research opportunities and implications for public policies in urban and transportation and public health.

• Atmosphere
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• v.22 no.1
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• pp.47-55
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• 2012

The characteristics of flow and pollutant dispersion for fire scenarios in an urban area are numerically investigated. A computational fluid dynamics (CFD) model coupled to a mesoscale weather research and forecasting (WRF) model is used in this study. In order to more accurately represent the effect of topography and buildings, the geographic information system (GIS) data is used as an input data of the CFD model. Considering prevailing wind, firing time, and firing points, four fire scenarios are setup in April 2008 when fire events occurred most frequently in recent five years. It is shown that the building configuration mainly determines wind speed and direction in the urban area. The pollutant dispersion patterns are different for each fire scenario, because of the influence of the detailed flow. The pollutant concentration is high in the horse-shoe vortex and recirculation zones (caused by buildings) close to the fire point. It thus means that the potential damage areas are different for each fire scenario due to the different flow and dispersion patterns. These results suggest that the accurate understanding of the urban flow is important to assess the effect of the pollutant dispersion caused by fire in an urban area. The present study also demonstrates that CFD model can be useful for the assessment of urban environment.

• Atmosphere
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• v.25 no.3
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• pp.449-459
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• 2015

Effects of buildings and topography on observation environment of surface wind in central regions of urban areas are investigated using a computational fluid dynamics (CFD) model. In order to reflect the characteristics of buildings and topography in urban areas, geographic information system (GIS) data are used to construct surface boundary input data. For each observation station, 16 cases with different inflow directions are considered to evaluate effects of buildings and topography on wind speed and direction around the observation station. The results show that flow patterns are very complicated due to the buildings and topography. The simulated wind speed and direction at the location of each observation station are compared with those of inflow. As a whole, wind speed at observation stations decreases due to the drag effect of buildings. The decrease rate of wind speed is strongly related with total volume of buildings which are located in the upwind direction. It is concluded that the CFD model is a very useful tool to evaluate location of observation station suitability. And it is expected to help produce wind observation data that represent local scale excluding the effects of buildings and topography in urban areas.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.40 no.4
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• pp.261-273
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• 2022

This study aims to predict the land use demand of Seongnam-city using system dynamics and to simulate the effect of changes in family structure and land use density adjustment policy on land use demand. This study attempted to construct causal loop diagrams and an analysis model. The changes in land use demand over time were predicted through simulation results. As a result of the analysis, as of 2035, an additional supply of 2.08 km² for residential land and 1.36 km² for commercial land is required. Additionally, the current supply area of industrial land can meet the demand. Three policy experiments were conducted by changing the variable values in the basic model. In the first policy experiment, it was found that when the number of household members decreased sharply compared to the basic model, up to 7.99 km² of additional residential land were required. In the second policy experiment, if the apartment floor area ratio was raised from 200% to 300%, it was possible to meet the demand for residential land with the current supply area of Seongnam-city. In the third policy experiment, it was found that even if the average number of floors in the commercial area was raised from four to five and the building-to-land ratio in the commercial area was raised from 80% to 85%, the demand for commercial land exceeded the supply area of the commercial area in Seongnam-city. This study is meaningful in that it proposes a new analytical model for land use demand prediction using system dynamics, and empirically analyzes the model by applying the actual urban planning status and statistics of Seongnam-city.

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2003.11a
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• pp.11-14
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• 2003

Development pollution control strategies relies on photo-chemical transport models. These models integrate of mesoscale meteorological models with chemical moduls. In this study, the PSU/NCAR mesoscale meteorological model with CAMx is used to investigate the temporal and spatial dynamics of the photochemical air pollution in urban atmosphere of Istanbul for selected high ozone days. The ozone climatology for the selected days and model simulations are presented.

• Journal of Environmental Science International
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• v.20 no.7
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• pp.839-843
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• 2011

We have established a wind map of Singapore, a city-state characterized its land cover by urban buildings to confirm a possibility of wind farm development. As a simple but useful approximation of urban canopy, a zero-plane displacement concept was employed. The territory is divided into 15 sectors having similar urban building layouts, and zero-plane displacement, equivalent roughness height at each sector was calculated to setup a terrain boundary condition. Annual mean wind speed and mean wind power density map were drawn by a CFD micrositing model, WindSim where Changi International Airport wind data was used as an in-situ measurement. Unfortunately, predicted wind power density does not exceed 80 $W/m^2$ at 50 m above ground level which would not sufficient for wind power generation. However, the established Singapore wind map is expected to be applied for wind environment assessment and urban planning purpose.

• Proceedings of the KSR Conference
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• 2004.10a
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• pp.357-362
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• 2004

Maglev vehicles, which are levitated and propelled by electromagnets, often run on elevated guideways comprised of steel, aluminum and concrete. Therefore, an analysis .of the dynamic interaction between the Maglev vehicle and the guideway is needed in the design of the critical speed, ride, controller design and weight reduction of the guideway. This study proposes a dynamic interaction simulation technique using a flexible beam model based on multi-body dynamics. The vehicle and the elevated guideway are represented as a multi-body dynamics model and a two-dimensional flexible beam, respectively. The proposed model was applied to an urban transit Maglev vehicle, UTM01, which is undergoing test drive. As a result of the proposed method, we concluded that it is possible to analyze the dynamic interaction between the Maglev vehicle and the guideway.