• Korean Management Science Review
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• v.17 no.1
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• pp.31-40
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• 2000

With the rapidly changing external environment and the increasing internal process complexity more and more organizations are adopting the Electronic Approval System(EAS) for their competitiveness. This paper defines EAS as a core organizational communication medium investigates factors which influence EAS's use from a media rich-ness theory and shows sutiable EAS functions for equivocality resolution and uncertainty reduction. Results from the five EAS implementation sites show that most organizations use EAS only for tasks with low equivocality and low uncertainty. Additional functionalities such as video conferencing and database access were suggested for fu-ture EAS system to enhance their utilization for more cirtical and unstructed tasks.

• Journal of the Korean Operations Research and Management Science Society
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• v.11 no.1
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• pp.44-50
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• 1986

In this paper, we find optimal policy for the (Q, r) inventory model under the lead time uncertainty. The (Q, r) inventory model is such that the fixed order quantity Q is placed whenever the level of on hand stock reaches the reorder point r. We first develop the single level inventory model as the basis for the analysis multi-level distribution systems. The functional problem is to determine when and how much to order in order to minimize the expected total cost per unit time, which includes the set up, inventory holding and inventory shortage cost. The model, then, is extended to the multi-level distribution system consisting of the factory, warehouses and retailers. In this case, we also find an optimal policy which minimizes the total cost of the contralized multi-level distribution system.

• Transactions on Control, Automation and Systems Engineering
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• v.3 no.3
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• pp.159-163
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• 2001

An input constrained receding horizon predictive control algorithm for uncertain systems with nonzero set points is proposed. for constant nonzero set points, models with uncertainty can be converted into an augmented incremental system through the use of integrators and the problem is transformed into a zero-state regulation problem for the incremental system. But the original constraints on inputs are converted into constraints on the sum of control inputs at each time instants, which have not been dealt in earlier constrained robust receding horizon control problems. Recursive state bounding technique and worst case minimizing strategy developed in earlier works are applied to the augmented incremental system to yield an offset error free controller. The resulting algorithm is formulated so that it can be solved using LP.

• Proceedings of the KIEE Conference
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• 1999.07b
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• pp.606-608
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• 1999

Mutual Recognition Agreement(MRA) between national metrology institutes is started on October 1999 and International Key Comparison is essentially to be used as technical basis for the agreement. High resistance is one of the Key Comparison and high resistance measurement system is established in KRISS for the purpose of the Key Comparison. Total combined uncertainty of the system is about 4ppm in $10M{\Omega}$ and 8ppm in $1G{\Omega}$. With the system, the difference of comparison results for $10M{\Omega}$ and $1G{\Omega}$ among KRISS, VNIIM in Russia and NIM in China is agreed about 6ppm within total combined uncertainty of three institutes.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.45.3-45
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• 2001

This paper deal with a fault detection algorithm for front wheel passenger car systems by using robust $H{\infty}$ control theory. Firstly, we present a unified formulation of vehicle dynamics for front wheel car systems and transform this formulation into state space form. Also, by considering the cornering stiffness which depends on the tyre-road contact conditions, a multiplicative uncertainty for vehicle model is described. Next, the failures of sensor and actuator for vehicle system are defined in which the fault .lter is considered. From the nominal vehicle model, an augmented system includes the multiplicative uncertainty and the model of fault filter is proposed. Lastly by using $H{\infty}$ norm property the fault detect conditions are deefi.ned, and the actuator and sensor failures are detected and isolated by designing the robust $H{\infty}$ controller, respectively.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.26 no.4
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• pp.539-546
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• 2002

The Holographic Particle Velocimetry system can be a promising optical tool leer the measurements of three dimensional particle velocities. In this research, validation experiments for the development of holographic particle velocimetry system for spray droplets were conducted with measuring the velocities of glass beads on a rotating disk. Uncertainty analysis was performed to identify the sources of all relevant errors and to evaluate their magnitude. The measurement results of distance between glass beads, size, and velocities obtained with holographic method are compared reasonably well with the known values within acceptable range of errors.

• 제어로봇시스템학회:학술대회논문집
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• 1999.10a
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• pp.1-4
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• 1999

This paper presents a design scheme of robust parallel compensator for plants with multiple uncertainty, which realizes strict positive realness of the closed-loop system by using static output feedback. Further, an ap-proximate relation between the static output feedback control system with the proposed compensator and the PID$.$‥D$\^$r-1 control system is shown.

• Transactions on Control, Automation and Systems Engineering
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• v.4 no.4
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• pp.289-295
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• 2002

In this paper, a linear matrix inequality(LMI)-based robust control method, which combines model predictive control(MPC) with the feedback linearization(FL), is presented for constrained nonlinear systems with parameter uncertainty. The design procedures consist of the following 3 steps: Polytopic description of nonlinear system with a parameter uncertainty via FL, Mapping of actual input constraint by FL into constraint on new input of linearized system, Optimization of the constrained MPC problem based on LMI. To verify the performance and usefulness of the control method proposed in this paper, some simulations with application to a flexible single link manipulator are performed.

• Transactions on Control, Automation and Systems Engineering
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• v.4 no.4
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• pp.356-362
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• 2002

In this paper, well-known Takagi-Sugeno fuzzy model is used as the nonlinear plant model and uncertainty is assumed to be included in the model structure with known bounds. Based on the fuzzy models, a numerical robust stability analysis for the fuzzy feedback linearization regulator is presented using Linear Matrix Inequalities (LMI) Theory. For these structured uncertainty, the closed system can be cast into Lur'e system by simple transformation. From the LMI stability condition for Lur'e system, we can derive the robust stability condition for the fuzzy feedback linearization regulator based on Takagi-Sugeno fuzzy model. The effectiveness of the proposed analysis is illustrated by a simple example.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.261-262
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• 2008

Failure Mode Effects and Criticality Analysis (FMECA) evaluates criticality and severity of each failure mode. Generally, those indices are determined subjectively by experts and operators. However, this process has no choice but to include uncertainty. In this paper, a method for eliciting expert opinions considering its uncertainty is proposed to evaluate the criticality and severity. In addition, a fuzzy expert system is constructed to determine the crisp value of risk level for each failure mode. The results are worth considering while deciding the proper policies for each component of the system.