• Proceedings of the Korea Inteligent Information System Society Conference
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• 2001.01a
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• pp.431-434
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• 2001

Knowledge discovery in databases(KDD) is the process for extracting valid, novel, potentially useful and understandable knowledge form real data. There are many academic and industrial activities with new technologies and application areas. Particularly, data mining is the core step in the KDD process, consisting of many algorithms to perform clustering, pattern recognition and rule induction functions. The main goal of these algorithms is prediction and description. Prediction means the assessment of unknown variables. Description is concerned with providing understandable results in a compatible format to human users. We introduce an efficient data mining algorithm considering predictive and descriptive capability. Reasonable pattern is derived from real world data by a revised neural network model and a proposed fuzzy rule extraction technique is applied to obtain understandable knowledge. The proposed neural network model is a hierarchical self-organizing system. The rule base is compatible to decision makers perception because the generated fuzzy rule set reflects the human information process. Results from real world application are analyzed to evaluate the system\`s performance.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.51 no.12
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• pp.611-623
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• 2002

This paper introduce the real time digital simulator which is located in Korea Electric Power Research Institute. This paper also describes the methodology for the performance test of the PSS using KEPS. This test is to get a high degree of the confidence of the developed PSS before it is installed into the real power system. This has been performed in the form of closed-loop tests in which Simulator and PSS are connected and signals come and back interactively. Many tests have successfully done using KEPS which consists of 26 RTDS racks, under the large-scale power system. The simulated reduced KEPCO power system contains 88 generators and 295 buses. Through the AVR step, three phase fault and active power variation test, the effectiveness of developed PSS has been proved. This paper also presents the overview of KEPS and hardware of protype PSS.

• 한국전산유체공학회:학술대회논문집
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• 2003.10a
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• pp.48-49
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• 2003

In the present research a high order Gudonov-type method has been used for the simulation of very high pressure flow fields, as well as the capturing of strong shocks, which usually occur in explosion of high explosives. The treatment strong shocks and the flow field behind the shocks needs a very high resolution scheme. To resolve accurately the shock and the release waves behind the shock the piece­wise parabolic method (PPM) of Colella [1] was utilized in this research. A major problem which encountered in very high pressure problems is the equation of state which differs completely form the ideal-gas equation of state (EOS). Here, the original PPM is extended for real gas effect consideration.

• 제어로봇시스템학회:학술대회논문집
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• 1995.10a
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• pp.348-351
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• 1995

This note proposes a robust LQR method for systems with structured real parameter uncertainty based on Riccati equation approach. Emphasis is on the reduction of design conservatism in the sense of quadratic performance by utilizing the uncertainty structure. The class of uncertainty treated includes all the form of additive real parameter uncertainty, which has the multiple rank structure. To handle the structure of uncertainty, the scaling matrix with block diagonal structure is introduced. By changing the scaling matrix, all the possible set of uncertainty structures can be represented. Modified algebraic Riccati equation (MARE) is newly proposed to obtain a robust feedback control law, which makes the quadratic cost finite for an arbitrary scaling matrix. The remaining design freedom, that is, the scaling matrix is used for minimizing the upper bound of the quadratic cost for all possible set of uncertainties within the given bounds. A design example is shown to demonstrate the simplicity and the effectiveness of proposed method.

• Journal of Institute of Control, Robotics and Systems
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• v.9 no.12
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• pp.1033-1041
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• 2003

A new visual tracking scheme is proposed for a mobile robot that tracks a moving object in 3D space in real time. Visual tracking is to control a mobile robot to keep a moving target at the center of input image at all time. We made it possible by simplifying the relationship between the 2D image frame captured by a single camera and the 3D workspace frame. To precisely calculate the input vector (orientation and distance) of the mobile robot, the speed vector of the target is determined by eliminating the speed component caused by the camera motion from the speed vector appeared in the input image. The problem of temporary disappearance of the target form the input image is solved by selecting the searching area based on the linear prediction of target motion. The experimental results have shown that the proposed scheme can make a mobile robot successfully follow a moving target in real time.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2000.11b
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• pp.344-353
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• 2000

Recent mechatronics technology is the most appropriate high technology in the agricultural application to save repetitious labor. Cow's body parameters were measured by traditional several measurer. Image processing technology was used to measure automatically their parameters to reduce lots of labor and time. The parameters were measured form a small model cow, which is easily measured, instead to a real cow. The image processing system designed and built for this project was composed of a Pentium PC, and TV frame card two cameras which were located on side and top of model cow. 11 parameters of cow's body were measured and the error between real data and the data by image processing was less than 10%. Based on the results of this research the parameters of a real cow could be measured in the future.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.7 no.1
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• pp.150-160
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• 1995

A Finkelstein adiabatic analysis is performed for Stirling refrigerator with real gas properties of helium. The mass balance and the energy balance equations are formulated into the form that is convenient for incorporating an available computer code of the helium properties. The differential equations are solved numerically. The calculated coefficient of performance(COP) and the pressure variation are compared with the results obtained when helium is assumed to be an ideal gas. The relative errors in COP are presented as functions of the refrigeration temperature and the maximum cycle pressure.

• Journal of Korean Institute of Industrial Engineers
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• v.17 no.2
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• pp.63-74
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• 1991

An expert scheduling system on real time basis for computer-aided manufacturing systems has been developed. In developing expert scheduling system, the most time-consuming job is to obtain rules from expert schedulers. An efficient process of obtaining rules directly form the schedules produced by expert schedulers is proposed. By the process, a set of complete and minimal set of rules is obtained. During a real time scheduling, when given information on possible values of elements, the rules produce possible values of decision elements, where logical explanations of the result may be offered in terms of chaining rules. The learning and scheduling processes have been simulated with an automated manufacturing line engaged in the production of circuit boards.

• Honam Mathematical Journal
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• v.27 no.3
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• pp.487-504
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• 2005

Let M be a real hypersurface with almost contact metric structure (${\phi}$, ${\xi}$, ${\eta}$, g) in a nonflat complex space form $M_n(c)$. We denote by A and S be the shape operator and the Ricci tensor of M respectively. In the present paper we investigate real hypersurfaces with $g(SA{\xi},\;A{\xi})=const$. of $M_n(c)$ whose structure Jacobi operator $R_{\xi}$ commute with both ${\phi}$ and S. We give a characterization of Hopf hypersurfaces of $M_n(c)$.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.1
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• pp.148-154
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• 2012

For a successful checkpointing strategy, we should place checkpoints so as to optimize fault-tolerance capability of real-time systems. This paper presents a novel scheme of checkpoint placement for real-time systems with periodic multi-tasks. Under the influence of transient faults, multi-tasks are scheduled by the Rate Monotonic (RM) algorithm. The optimal checkpoint intervals are derived to maximize the probability of task completion. In particular, this paper is concerned about the general case that the deadline of a task is longer than the period. Compared with the special condition that the deadline is equal to or less than the period, this general case causes a more complicate test procedure for schedulability of the RM algorithm with respect to a given set of checkpoint re-execution vectors. The probability of task completion is also derived in a more complex form. A case study is given to show the applicability of the proposed scheme.