• Proceedings of the KSRS Conference
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• 2008.10a
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• pp.410-413
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• 2008

Existing Outlier detections have been widely studied in geosensor networks. Recently, machine learning and data mining have been applied the outlier detection method to build a model that distinguishes outliers based on anchored criterion. However, it is difficult for the existing methods to detect outliers against incoming time-variant data, because outlier detection needs to monitor incoming data and classify irregular attacks. Therefore, in order to solve the problem, we propose a time-variant outlier detection using 2-dimensional grid method based on unanchored criterion. In the paper, outliers using geosensor data was performed to classify efficiently. The proposed method can be utilized applications such as network intrusion detection, stock market analysis, and error data detection in bank account.

• Journal of Drive and Control
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• v.10 no.3
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• pp.21-26
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• 2013

This paper presents a robust motion tracking control of a cylinder-toggle servomechanism for injection molding machines. Virtual design model has been developed for a five-point type toggle mechanism. A sliding function is defined and combined with PID control to accommodate mismatches between the real plant and the linear model used. From tracking control simulations, it is shown that significant reduction in position tracking error is achieved with clamping force build-up through the use of proposed control scheme.

• Journal of information and communication convergence engineering
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• v.8 no.6
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• pp.709-715
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• 2010

This paper represents a map building and localization system for mobile robot. Map building and navigation is a complex problem because map integrity cannot be sustained by odometry alone due to errors introduced by wheel slippage, distortion and simple linealized odometry equation. For accurate localization, we propose sensor fusion system using encoder sensor and indoor GPS module as relative sensor and absolute sensor, respectively. To build a map, we developed a sensor based navigation algorithm and grid based map building algorithm based on Embedded Linux O.S. A wall following decision engine like an expert system was proposed for map building navigation. We proved this system's validity through field test.

• The Mathematical Education
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• v.46 no.2 s.117
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• pp.141-153
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• 2007

The purpose of the study is to analyze children's proportional reasoning and problem solving in proportional problems with/without iconic representations. Proportional problems include 3 tasks such as (a) without any picture, (b) with simple picture, and (c) with/without iconic representation. As a result, children didn't show any significant differences in two tasks such as (a) and (b). However, children showed better proportional reasoning with iconic representation. In addition, 'build-up expression' strategy was used mostly in solving problems and 'additive strategy' was shown as an error which students didn't make an appropriate proportional relation expression and they made a wrong additive strategy.

• International Journal of Control, Automation, and Systems
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• v.6 no.4
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• pp.613-619
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• 2008

A method to produce a desired current pattern in a multiple-source EIT system using voltage sources is presented. Application of current patterns to a body is known to be superior to the application of voltage patterns in terms of high spatial frequency noise suppression, resulting in high accuracy in conductivity and permittivity images. Since current sources are difficult and expensive to build, the use of voltage sources to apply the current pattern is desirable. An iterative algorithm presented in this paper generates the necessary voltage pattern that will produce the desired current pattern. The convergence of the algorithm is shown under the condition that the estimation error of the linear mapping matrix from voltage to current is small. Simulation results are presented to illustrate the convergence of the output current.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.34 no.2
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• pp.30-34
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• 2011

Variable precision rough set models have been successfully applied to problems whose domains are discrete values. However, there are many situations where discrete data is not available. When it comes to the problems with interval values, no variable precision rough set model has been proposed. In this paper, we propose a variable precision rough set model for interval values in which classification errors are allowed in determining if two intervals are same. To build the model, we define equivalence class, upper approximation, lower approximation, and boundary region. Then, we check if each of 11 characteristics on approximation that works in Pawlak's rough set model is valid for the proposed model or not.

• Journal of Sensor Science and Technology
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• v.25 no.6
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• pp.394-398
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• 2016

In this paper, a fire detection system based on quantitative risk estimation is presented. Multiple sensors are used to build a comprehensive indicator that represents the risk of fire quantitatively. The proposed fire risk estimation method consists of two stages which determines the occurrence of fire and estimates the toxicity of the surveillance area. In the first stage, fire is reliably detected under diverse fire scenarios. The risk of fire is estimated in the second stage. Applying Purser's Fractional Effective Dose (FED) model which quantitates harmfulness of toxic gases, the risk of the surveillance area and evacuation time are calculated. A fire experiment conducted using four different types of combustion materials for the verification of the system resulted in a maximum error rate of 12.5%. By using FED calculation and risk estimation methods, the proposed system can detect various signs of fire faster than conventional systems.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.603-604
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• 2005

A precise ratio transformer which is used to a ratio arm of a precise impedance measurement bridge at low frequencies was developed. The developed ratio transformer has the ratio taps of 1:1, 2:1, $\cdots$, to 10:1 in order to measure the primary impedance standards by substitution and special winding techniques for 10:1 ratio that is used frequently for impedance build up/down. The calibration results of the transformer has inphase and quadrature error of $0.073\times10^{-6}$ and $0.14\times10^{-6}$ respectively at 1.6 kHz.

• Proceedings of the KIEE Conference
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• 2004.05a
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• pp.144-146
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• 2004

It is known that Global Positioning System(GPS) is the most efficient navigation system because it provides precise position information on the all areas of Earth regardless of metrology. Until now, the size of GPS receivers has become smaller and the performance of receivers has become higher. So receivers provide the position information of not only static system but also dynamic system. Usually, users make similar movement trajectory according to their life pattern and it is possible to build up efficient database by collecting only the repeated users' position. Because position information calculated by the receiver is erroneous about 10-30m within 5% error tolerance, the position information is oscillated even on the same area. In this paper, we propose the system that can estimate whether users are out of trajectory or in dangerous situation by soft-computing method.

• Journal of the Korean Society for Precision Engineering
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• v.25 no.5
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• pp.89-95
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• 2008

The Acousto-Optic Tunable Filter (AOTF) is a high-speed full-field monochromator which generates two spectrally filtered light beams with ordinary and extraordinary polarization state. Thus, AOTF is widely used to build full-field spectral imaging system or spectral domain interferometer. However, AOTF has a big problem that the angle of diffracted light changes according to the scanning of wavelength, which makes image shift on CCD plane In this paper, we propose an analytic design of prism system to compensate the image shift. The detailed analysis of light paths in a prism and basic experimental results are presented to verify our proposed compensation method. The experimental results agree with simulation results based on suggested prism model and image shift is minimized at optimal condition. Also, it can be extended to compensate the image shift for ordinary and extraordinary polarized light simultaneously.