• Journal of Mechanical Science and Technology
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• v.15 no.6
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• pp.699-708
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• 2001

This paper presents a new approach to the AFR (Air-to-Fuel Ratio) control problem, which is based on the wide-band oxygen sensor output. The dedicated nonlinear controller is based on the feedback lineaization technique. It is well known that the feedback linearizing control technique requires an exact model of the plant for the cancellation of plant nonlinearities. A sliding mode control scheme is applied which can effectively compensate the modeling uncertainties. The measurement time delay of an oxygen sensor limits the gain of the feedback controller. Hence, time delay compensation procedure is necessary for the improvement of control performance. The Smith predictor is adopted to compensate the effects of time delay. The simulation and experimental results show that the proposed controllers can effectively reduce the transient peaks of AFR in spite of fast tip-in and tip-out maneuvers of the throttle.

• Proceedings of the Korea Contents Association Conference
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• 2006.05a
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• pp.440-443
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• 2006

In this paper, we implemented design pattern retrieval system for efficient management and reusability of design patterns. Pattern is consisted of property information and meta information. Property information is used for similarity measurement on classification and retrieval of patterns. Meta information is used for UML modeling of patterns. We classified design patterns with the empirical scope in addition to Gamma's basic classification.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.5 no.1
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• pp.183-191
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• 2001

We develop the new data s]ice representation, called the data value flow graph(VFG), for modeling the information flow oil data slices. Then we define a slice complexity measure by using the existing flow complexity measure in order to measure the complexity of the information flow on VFG. We show relation of the slice complexity on a slice with the slice complexity on a procedure. We also demonstrate the measurement scale factors through a set of atomic modifications and a concatenation operator on VFG.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10b
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• pp.812-815
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• 1996

In this paper, we consider the optimal control problem based on Discrete Event Dynamic Systems(DEDS) in the Temporal Logic framework(TLF) which have studied for a convenient modeling technique. The TLF is enhanced with objective functions(event cost indices) and a measurement space is also defined. Our research goal is the design of the optimal controller for DEDSs. This procedure could be guided by the heuristic search methods. For the heuristic search, we suggested the Stochastic Ruler algorithm, instead of the A algorithm with difficulties as following; the uniqueness of solutions, the computational complexity and how to select a heuristic function. This SR algorithm is used for solving the optimal problem. An example is shown to illustrate our results.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2006.11a
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• pp.277-280
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• 2006

This paper describes the aerodynamic interference characteristics between the ing and the engines in a commercial airplane which is realized by reverse engineering based on the photo measurement. Steady three-dimensional compressible inviscid Euler equation is solved in the unstructured grid system under the cruise condition. The lift and drag forces in the wing with engines increase by 1.49% and 3.9%, respectively compared with the wing without engines.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.29-30
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• 2008

This paper defines a concept of "protectability" for the performance evaluation of distance relay considering its sensitivity and selectivity. The paper starts from the probabilistic modeling of the errors, and based on this model, a detailed explanation of protectability calculation for each zone of the distance relay is presented. An effect of the Weighting Rate and the Measurement Deviation on the protectability evaluation is also given. By considering this effect, the optimization of relay setting can be realized. The proposed method is applied to a typical model system to show its effectiveness.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.15 no.4
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• pp.16-22
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• 2016

This study is a structural analysis of 3" Cryogenic Safety Breakaway Coupling using a manufactured product from KLAW Company. Breakaway coupling is very important in the pipe system, especially when transporting fuel or gas in the pipeline. For the analysis of the patent infringement target, Dover and KLAW Company's technologies (US 08127785, EP 0764809) were analyzed. Finally, the flip-flap valve overlap was measured after combining the breakaway coupling through 3D modeling, and the valve overlap had a 0.7mm measurement value from the height gauge. The safety breakaway coupling consisted of a total of 62 pieces (body: 42, valve module: 21).

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.188-188
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• 2000

The most important problem in target tracking can be said to be modeling the tracking system correctly. Although the simple linear dynamic equation for this model has used until now, the satisfactory performance could not be obtained owing to uncertainties of the real systems in the case of designing the filters baged on the dynamic equations. In this paper, we propose the extended robust Kalman filter (ERKF) which can be applied to the real target tracking system with the parameter uncertainties. A nonlinear dynamic equation with parameter uncertainties is used to express the uncertain system model mathematically, and a measurement equation is represented by a nonlinear equation to show data from the radar in a Cartesian coordinate frame. To solve the robust nonlinear filtering problem, we derive the extended robust Kalman filter equation using the Krein space approach and sum quadratic constraint. We show the proposed filter has better performance than the existing extended Kalman filter (EKF) via 3-dimensional target tracking example.

• Proceedings of the KIEE Conference
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• 1997.07c
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• pp.1180-1183
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• 1997

This paper addresses the issues of the external system modeling and power system state estimation with the external model. A set of significant measurements is identified in the external system based on their sensitivities on the tie-lines. These measurement data are transferred to internal system and updated in real-time. The state estimator is run for different loading conditions by using the actual values for the internal system and selected significant external system measurements while keeping the rest of the external system measurements at their base case values. Simulation results are presented using the IEEE 118 bus system as an example.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1041-1042
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• 2007

This paper proposes a new method for detecting broken rotor bars in a squirrel-cage induction motor. The air-gap flux variation analysis was done using search coils inserted in stator slots when broken rotor bar occurs. An accurate modeling and analysis of air-gap flux variation in the induction motor are developed using finite-element (FE) software packages, and measurement of the flux are made using search coils. The simulation was done for the induction motor with 380 [V], 7.5 [kW], 4 Poles, 1,760 [rpm] ratings using the commercial FE analysis tool. The simulation and experiment results can be useful for detecting the broken rotor bar of an induction motor.