• Journal of the Korea Institute of Building Construction
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• v.9 no.2
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• pp.63-68
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• 2009

Construction Performance measurement and management has been interested by construction practitioners. However, current construction project management practices are related to short-term improvement plans rather than long-term and systematic approaches based upon performance analysis. AR a result, there is a need for developing of a collaborative plan over project life cycle. Therefore, this paper reviews extensive literature and proposes the construction performance estimating model using a system dynamics. The paper proposes casual maps for planning, design, procurement, and construction phases. Each casual map includes all performance indicators and factors that impact on performance directly or indirectly. These casual maps that were developed by system thinking will enhance the understanding of the relationships among performances and factors. After further data gathering, these models can be used to estimate construction performance and eventually these will save project costs and shorten project schedule.

• International Journal of Automotive Technology
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• v.8 no.5
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• pp.605-614
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• 2007

This paper presents the research results for the reduction of a gear whine noise based on experimental and analytic methods. The test vehicle has a whine noise problem at the passenger seats in a sport utility vehicle. To identify the transfer path of the interior noise due to the axle system, a vibration path analysis, modal analysis and operational deflection shape analysis are systematically employed. By using these various methods, it has been found that the interior noise generated by the axle system was airborne noise. To reduce and predict the whine generated by the axle system, structural modifications for the axle system are performed by using FEM and BEM techniques. The structural modification of the axle cover is suggested for the reduction of whine noise.

• International Journal of Automotive Technology
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• v.7 no.1
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• pp.25-34
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• 2006

For decades, simulation technique has been well validated in areas such as computer and communication systems. Recently, the technique has been much used in the area of transportation and traffic forecasting. Several methods have been proposed for investigating complex traffic flows. However, the dynamics of vehicles and diversities of driver characteristics have never been considered sufficiently in these methods, although they are considered important factors in traffic flow analysis. In this paper, we propose a traffic simulation tool called Multi-Agent for Traffic Simulation with Vehicle Dynamics Model (MATDYMO). Road transport consultants, traffic engineers and urban traffic control center managers are expected to use MATDYMO to efficiently simulate traffic flow. MATDYMO has four sub systems: the road management system, the vehicle motion control system, the driver management system, and the integration control system. The road management system simulates traffic flow for various traffic environments (e.g., multi-lane roads, nodes, virtual lanes, and signals); the vehicle motion control system constructs the vehicle agent by using various vehicle dynamic models; the driver management system constructs the driver agent capable of having different driving styles; and lastly, the integrated control system regulates the MATDYMO as a whole and observes the agents running in the system. The vehicle motion control system and driver management system are described in the companion paper. An interrupted and uninterrupted flow model were simulated, and the simulation results were verified by comparing them with the results from a commercial software, TRANSYT-7F. The simulation result of the uninterrupted flow model showed that the driver agent displayed human-like behavior ranging from slow and careful driving to fast and aggressive driving. The simulation of the interrupted flow model was implemented as two cases. The first case analyzed traffic flow as the traffic signals changed at different intervals and as the turning traffic volume changed. Second case analyzed the traffic flow as the traffic signals changed at different intervals and as the road length changed. The simulation results of the interrupted flow model showed that the close relationship between traffic state change and traffic signal interval.

• Korean System Dynamics Review
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• v.1 no.2
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• pp.5-31
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• 2000

The summit meeting of the South North Korean leaders was a turning point in the relationships between the two countries. It was followed by the Red-Cross Meeting, Minister-Level Meeting, economic agreements, which have increased the relationship more colorful in both quantities and qualities. However, the half-century period for separation was too long to overcome all the problems by only one event. The two countries have quite different social systems; one politically strong person is governing the North, while many interest groups are involved in political decision making processes in the South. In short, it would take a long time to settle down all the problems residing between the two countries. A system dynamics model is developed to describe the long term dynamics of the relations between the South and North Koreas. As a first attempt, the model focuses only on the diplomatic meeting issues between the South and North. The model aggregates diplomatic issues into 5 categories; economic issues, security issues, infrastructure, cultural issues, and past problems. It assumes that there would not be any dramatic changes between the two countries. It is a conceptual model composed of around 200 variables, and should not be used as a forecast tool. However, it captures most of the logics discussed in the papers and conferences concerning the South and North Korea relations. Many sensitivity studies and Monte Carlo simulations have shown that the simulation results matches with mental models of experts; that is the model can be used as a learning tool or as a secondary opinion until the data required by the model is collected. In order to analyze the current situation, five scenarios are simulated and analyzed; the functional approach, the conditional approach, the balanced approach, the circumstantial approach, and the strategic approach. The functional approach represents that the South makes efforts in the area where the possibility of agreement is high for the next 10 years. The conditional approach is a scenario where the South impose all difficult issues as conditions for resolving other diplomatic issues. The balanced approach is resolving the five issues with the same priorities, while the circumstantial approach is resolving issues which seem to be resolved easily. Finally, another optimum approach has been seek using the system dynamics model developed. The optimum strategy (it is named as the strategic approach) was strikingly different from other four approaches. The optimum strategy is so complicated that no one could find it with mental model(or by just insights). Considering that the system dynamic model used to find the optimum is a simplifind (maybe over simplified) version of the reality, it is concluded that a well designed system dynamics model would be of great help to resolving the complicated diplomatic problems in any kind.

• Korean System Dynamics Review
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• v.9 no.2
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• pp.45-75
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• 2008

Roe Deer has been preserved for 25 years by the local government and the residents in Jejudo. However, the damage and harm of crops of the residents by Roe Deer are increasing as well. So, some experts worry about the unstability of ecosystem in Mt. Halla where Roe Deer live. This paper discuss the suitable number of Roe Deer population in Jejudo to protect the ecosystem in Mt. Halla and minimize the damage of residents in Jejudo. With system dynamics modeling and simulation, the population of Roe Deer at present is estimated about 2,300. However, the population of Roe Deer stays 'unstable balance'. So, a little change such as poaching and the increase of wild dogs may make the balance of ecosystem broken. According to the result of policy test simulation, we should keep on watching the poaching and maintain the number of wild dogs at about 100, so that the ecosystem in Jejudo can be stable. To reduce the moving of Roe Deer to low region, moreover, we should protect the Mt. Halla which is Roe Deer's habitat. If we are indifferent about these efforts, the ecosystem of Roe Deer in Mt. Halla will be ruined.

• Korean System Dynamics Review
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• v.1 no.2
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• pp.113-148
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• 2000

In 1987, The Brundtland Report defined a sustainable development as the development that meets the needs of the present without compromising the ability of future generations to meet their own needs. This is the concept that we should cling to, to preserve natural resources of the present for the future generation. With this concept in mind, this paper criticized the current waste management policy has been neglecting resource preservation aspect of waste management policy while giving too much emphasis on reducing waste generation. Thus, the purpose of this paper is to analyze how waste management policy can affect preservation of natural resources, and to investigate policy alternatives that can reduce both the volume of wast geverated and the amount of natural resources that need to be consumed in the production process. The study was conducted based on the literature survey and system dynamics simulation. Borrowing Randers and Meadows's solid waste model with some modification of parameter and variables, this paper simulate several policy alternatives to figure out the most effective waste management policy set that can meet the need of the present without compromising the ability of the future generation to meet their own needs. Main concern was how to link waste management policy with resource management policy that can lead to minimization of waste generation and resource consumption.

• 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.

• Proceedings of the KIEE Conference
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• 1992.07a
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• pp.381-385
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• 1992

In this paper, dynamic modeling and adaptive control problems for a space robot system are discussed. The space robot consist of a robot manipulator mounted on a free-floating base where no attitude control is applied. Using an extended robot model, the entire space robot can be viewed as an under-actuated robot system. Based on nonlinear control theory, the extended space robot model can then be decomposed into two subsystems: one is input-output exactly linearizable, and the other is unlinearizable and represents an internal dynamics. With this decomposition, a normal form-augmentation approach and an augmented state-feedback control are proposed to facilitate the design of adaptive control for the space robot system against parameter uncertainty, unknown dynamics and unmodeled payload in space applications. We demonstrate that under certain conditions, the entire space robot can be represented as a full-actuated robot system to avoid the inclusion of internal dynamics. Based on the dynamic model, we propose an adaptive control scheme using Cartesian space representation and demonstrate its validity and design procedure by a simulation study.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.1446-1449
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• 2008

Immune system is composed of multiple cells with distinct functions, and immune responses are orchestrated by complex and dynamic cell-cell interactions. Therefore, each cell behavior and function should be understood under right spatio-temporal context. Studying such complexity and dynamics has been challenging with conventional biological tools. Recent development of new technologies such as state of art imaging instruments and microfabrication techniques compatible with biological systems have provided many exciting opportunities to dissect complex and dynamic immune cell interactions; new microscopy techniques enable us to observe stunning dynamics of immune system in real time. Microfabrication permits us to manipulate microenvironments governing molecular/cellular dynamics of immune cells to study detailed mechanisms of phenomena observed by microscopy. Also, microfabrication can be used to engineer microenvironments optimal for specific imaging techniques. In this presentation, I am going to present an example of how these two techniques can be combined to tackle challenging problems in immunology. Obviously, this strategy can readily be applied to many different fields of biology other than immunology.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2005.05a
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• pp.370-376
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• 2005

This paper is described the program algorithm which can easily estimate dynamics of test support system by using mathematica tool based on the finite element method. We can determine the geometry, dimensions of the test support system, through tool stated in this paper for a certain test conditions. As a result of computer simulation and manufactured test support system's experiment in oder to verify suggested program, the dynamics of the test support system was well correspondent each other.