• 대한안전경영과학회지
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• 제11권3호
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• pp.19-26
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• 2009

It is becoming more and more important to develop safety-critical systems with special attention. Examples of the safety-critical systems include the mass transportation systems such as high speed trains, airplanes, ships and so forth. Safety critical issues can also exist in the development of atomic power plants that are attracting a great deal of attention recently as oil prices are sky-rocketing. Note that the safety-critical systems are in general large-scale and very complex for which case the effects of adopting the systems engineering (SE) approach has been quite phenomenal. Furthermore, safety-critical requirements should necessarily be realized in the design phase and be effectively maintained thereafter. In light of these comments, we have considered our approach to developing safety-critical systems to be based on the method combining the systems engineering and safety management processes. To do so, we have developed a design environment by constructing a whole life cycle model in two steps. In the first step, the integrated process model was developed by integrating the SE (ISO/IEC 15283) and systems safety (e.g., hazard analysis) activities and implemented in a computer-aided SE tool environment. The model was represented by three hierarchical levels: the life-cycle level, the process level, and the activity level. As a result, one can see from the model when and how the required SE and safety processes have to be carried out concurrently and iterately. Finally, the design environment was verified by the computer simulation.

• International Journal of Naval Architecture and Ocean Engineering
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• 제6권2호
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• pp.484-495
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• 2014

This paper introduces the use of network theory to model and analyze disparate ship design information. This work will focus on a ship's distributed systems and their intra- and intersystem structures and interactions. The three system to be analyzed are: a passageway system, an electrical system, and a fire fighting system. These systems will be analyzed individually using common network metrics to glean information regarding their structures and attributes. The systems will also be subjected to community detection algorithms both separately and as a multiplex network to compare their similarities, differences, and interactions. Network theory will be shown to be useful in the early design stage due to its simplicity and ability to model any shipboard system.

• Asia pacific journal of information systems
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• 제4권2호
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• pp.131-164
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• 1994

A contingency model of outsourcing is developed from the information systems (IS) literature and strategic management literature in order to assess the following question: What factors influence change in the extent to which an organization outsources IS functions? Based on the literature, this study identifies four IS factors-gaps in information quality, IS support quality, IS staff quality, and IS cost effectiveness-and three organizational factors-the gap in financial performance, strategic orientation, and the role of information technology in an organization-that influence the change in degree of outsourcing. These factors are hypothesized to influence the change in the extent of an organization's outsourcing of IS functions. From a mail survey of 188 top IS executives in U.S. companies, the results of analysis of covariance and bivariate correlational and multivariate regression analyses provide the following major findings: (a) This study found support for the proposed research model. (b) The change in the degree of IS outsourcing is determined by gaps in information quality, IS support quality, IS cost effectiveness, and financial performance and by the role of IT among IS and organizational factors.

• 산업경영시스템학회지
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• 제22권51호
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• pp.63-72
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• 1999

Many firms have applied flexible manufacturing systems as a means of increasing productivity, profitability, and quality. Therefore, the purpose of this paper is to develop the more efficient justification model through an analytical scoring model with the quantitative factors, flexibility factors, and safety factors under uncertainty. In this paper, the three factors for properly comparing and evaluating of flexible manufacturing systems are presented. Especially, this paper has emphasized the flexibility and safety factor; the one consists of organization assessment, process treatment function, products and products quantity, useful life assesment, and software function, the other presents risk assesment, Y2K problem, safety device analysis, total productive management system, safety management. Finally, a normalized scoring model by the new flexibility and safety factors can be used in real fields for flexible manufacturing systems project selection under uncertainty.

• 한국ITS학회 논문지
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• 제10권6호
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• pp.15-23
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• 2011

운전자는 바로 앞에서 주행하는 차량과 그 앞에서 주행하는 차량에 영향을 받는다는 것은 일반적으로 알려져 있다. 앞차를 통해서 그 앞차까지도 볼 수 있는 경우에는 해당차량에 대해서도 반응을 하면서 운전을 한다고 추정되며 이러한 추종모형을 Three-Car-Following Model이라고 한다. 차량군에서 가장 뒤에 따라가는 운전자의 가시권 확보가 차량틴팅에 영향을 받으므로, 모형의 파라메터도 영향을 받게 될 것으로 추정되며, Three-Car-Following Model이 가정하는 운전자는 앞차, 그리고 또 그 앞차의 주행상태에 반응한다는 것을 반증하는 결과가 될 수 있다. 이에 본 연구에서는 Three-Car-Following Model의 파라메터를 추정하고, 차량의 틴팅정도가 달라질 때, 파라메터값이 어떻게 달라지는지에 대한 분석을 수행하였다. RTK GPS를 통해 수집된 자료를 이용하여 3대 차량간의 가시광선 투과율별 민감도 및 ${\gamma}$ 분석을 시행하였으며, 통계적 검증을 통해 운전자가 바로 앞에 주행하는 차량뿐만 아니라 그 앞에서 주행하는 차량에도 영향을 받는다는 것을 확 인하였다. 또한, 틴팅으로 가시광선 투과율이 낮아지면 가시권이 줄어들고, 이로 인해 앞차량들의 운전행태에 더욱 민감한 반응을 보이는 것으로 확인하였다. 차량의 틴팅정도에 따라 교통류의 용량에 미치는 영향분석에 관한 연구는 향후 과제로 남긴다.

• 한국지능시스템학회논문지
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• 제7권4호
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• pp.29-39
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• 1997

A discrete model reference control scheme for a vehicle four wheel steering system(4WS) is proposed and evaluated for a class of discrete time nonlinar dynamics. The schmen employs a neural network to identify the plan systems, wher the neural network estimates the nonlinear dynamics of the plant. The algorithm is proven to be globally stable, with tracking errors converging to the neighborhood of zero. The merits of this scheme is that the global system stability is guaranteed. Whith thd resulting identification model which contains the neural networks, the parameters of controller are adjusted. The proposed scheme is applied to the vehicle active four wheel system and shows the validity and effectiveness through simulation. The three-degree-of freedom vehicle handling model is used to investigate vehicle handing performances. In simulation of the J-turn maneuver, the yaw rate overshoot reduction of a typical mid-size car is improved by 30% compared to a two wheel steering system(2WS) case, resulting that the proposed scheme gives faster yaw rate response andl smaller side slip angle than the 2WS case.

• 수산해양기술연구
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• 제44권1호
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• pp.46-56
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• 2008

A numerical model analysis was performed to analyze the motion and mooring tension response of submersible fish cage systems in irregular waves and currents. Two systems were examined: a submersible cage mooring with a single, high tension mooring and the same system, but with an additional three point mooring. Using a Morison equation type model, simulations of the systems were conducted with the cage at the surface and submerged. Irregular waves(JONSWAP spectrum) with and without a co-linear current with a magnitude of 0.5m/s were simulated into the model as input parameters. Surge, heave and pitch dynamic calculations were made, along with tension responses in the mooring lines. Results were analyzed in both the time and frequency domains and linear transfer functions were calculated.

• Asia pacific journal of information systems
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• 제10권4호
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• pp.77-100
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• 2000

Information technology(IT) has become the fourth major resource available to executives to shape and operate government and public organizations. Government and public organizations have managed the other three major resources for years : people, money, and machine. But today IT accounts for more than 10 % of the budget spent in the Korean government and public organizations. From an information resource management point of view, therefore, data and information, hardware and software, telecommunications networks, information systems personnel and other factors are valuable resources that should be managed for the benefit of the entire organization. This paper studied on the model of information resource management(IRM) architecture for government and public organizations and suggested a new generic model for IRM. The model is consisted of four basic architectures and each architecture includes several factors that should be managed for the benefit of the entire government and public organizations.

• 대한산업공학회지
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• 제41권5호
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• pp.425-438
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• 2015

This study proposes a three-stage model of R&BD performance which captures commercialization outcomes as well as conventional R&D performance. The model is composed of three factors : inputs (R&D budgets and researchers), outputs (patents and papers), and outcomes (technical fees, products sales, and cost savings). Three stages are defined for each transformation process between the three factors : efficiency stage from input to output (stage 1), effectiveness stage from output to outcome (stage 2), and productivity stage from input to outcome (stage 3). The performance of each stage is measured by data envelopment analysis (DEA). DEA is a non-parametric efficiency measurement technique that has widely been used in R&D performance measurement. We measure the performance of 171 projects of 6 public R&BD programs managed by Seoul Business Agency using the proposed three-stage model. In order to provide a balanced and holistic view of R&BD performance, the R&BD performance map is also constructed based on performance of efficiency and productivity stages.

• International Journal of Control, Automation, and Systems
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• 제4권2호
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• pp.255-270
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• 2006

In this paper, a design method of nonlinear autopilot for ship-to-ship missiles is proposed. Ship-to-ship missiles have strongly coupled dynamics through roll, yaw, and pitch channel in comparison with general STT type missiles. Thus it becomes difficult to employ previous control design method directly since we should find three different solutions for each control fin deflection and should verify the stability for more complicated dynamics. In this study, we first propose a control loop structure for roll, yaw, and pitch autopilot which can determine the required angles of all three control fins. For yaw and pitch autopilot design, missile model is reduced to a minimum phase model by applying a singular perturbation like technique to the yaw and pitch dynamics. Based on this model, a multi-input multi-output (MIMO) nonlinear autopilot is designed. And the stability is analyzed considering roll influences on dynamic couplings of yaw and pitch channel as well as the aerodynamic couplings. Some additional issues on the autopilot implementation for these coupled missile dynamics are discussed. Lastly, 6-DOF (degree of freedom) numerical simulation results are presented to verify the proposed method.