• 제어로봇시스템학회:학술대회논문집
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• 1986.10a
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• pp.281-285
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• 1986

In this paper, the characteristics of disturbance torque of gimbal servo dynamics are studied, and the simulation methods of gimbal servo dynamics and INS error due to angular rate and linear acceleration of vehicle are proposed. In results of the simulation for a specific INS, it is estimated that INS velocity error due to gimbal servo dynamics is nearly proportional to square of vehicle acceleration.

• Proceedings of the IEEK Conference
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• 2001.06a
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• pp.85-88
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• 2001

In this paper, we propose a retransmission based error control scheme in which a stop-and-wait ARQ is simultaneously performed in two adjacent layers for the node-to-node error control. We develop an analytical numerical method to calculate the probability of error remains and the moments of the high layer message delay time at steady state. Using the analytical method, we investigate the performance of double-layered ARQ scheme with respect to the properties of the employed CRC codes and the characteristics of the involved channel.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.854-855
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• 2008

This paper deals with the computation error produced in the time step analysis for a electric machine with eddy current. To investigate the error in quantity, the analytic equations representing the steady state results of time-step analysis are deduced. Using the equations, the characteristics of errors are calculated for a general electric circuit, with variation of the circuit parameters and step size.

• Proceedings of the KIEE Conference
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• 1988.07a
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• pp.285-289
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• 1988

This paper suggests the way to improve the impulse response characteristics in 1-D and 2-D FIR digital filters design. The proposed a Least Square($L_2$) error algorithm of kaiser window is the better than $L_2$ error of the Remez Exchange(R.E.)algorithm.

• Journal of Institute of Control, Robotics and Systems
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• v.19 no.2
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• pp.95-101
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• 2013

The paper investigates the geometric effect of landmarks to the navigation error in the landmark based 3D vision navigation and introduces the INS/Vision integrated navigation system considering its effect. The integrated system uses the vision navigation results taking into account the dilution of precision for landmark geometry. Also, the integrated system helps the vision navigation to consider it. An indirect filter with feedback structure is designed, in which the position and the attitude errors are measurements of the filter. Performance of the integrated system is evaluated through the computer simulations. Simulation results show that the proposed algorithm works well and that better performance can be expected when the error characteristics of vision navigation are considered.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.1355-1359
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• 2004

The two way subscriber transmission systems have tendency to spread its carrier frequency bandwidth or information bit rate and average bit error rate according to popularization of high speed information through the digital communication system, transmission medium and the Internet. This fact is an important incentive to realize new systems. These two way subscriber transmission systems usually use same cable or same carrier frequency bandwidth for up stream channel and down stream channel. In the systems, the disturbances of noise, crosstalk or fading affect the characteristics. Specifically, these disturbances cause the decrease of information bit rate and degradation of transmission quality. This paper proposes the improved method of their degradations using the particular feature of two way subscriber transmission systems and it makes clear proposed method is effective by theoretically and some numerical examples.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.30B no.12
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• pp.87-97
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• 1993

To improve the limitation of fuzzy PI controller when is applied to systems of order higher than one, a fuzzy PI controller that fuzzily resets or amplifies the accumulated control input according to fuzzy rules defined on (error, change of error) space is proposed. The proposed controller structure was motivated by the characteristics of fuzzy PI controller that it generally gives unevitable large overshoot in trial of reducing rise time of response especially when a system of order higher than one is considered. Based on the observation that the undesirable characteristics of the fuzzy PI controller is caused by integrating control input excessively, even though the integrator is introduced to overcome steady state error, we propose a controller that clear out or doubles integrated control input in a fuzzy manner according to the situation to reduce rise time as well as overshoot. To show the usefulness of the proposed controller, it is applied to the systems that are difficult to stabilize or difficult to get satisfactory response by conventional fuzzy PI controllers.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.05a
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• pp.984-987
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• 2002

Abrasive water-jet(AWJ) machining is a new cutting technology. The AWJ can cut various materials such as metal, glass and stone. However, the AWJ machining makes troubles including kerf, rounding and side taper. In this study, we investigated the correlation between parameters of abrasive water-jet machining and cutting characteristics. The machining parameters were the material thickness and the traverse speed. The experiment was conducted to cut the stainless steel(STS41) and the mild steel(SS41) specimens. The results of the experiment were presented as the relation between cutting conditions and troubles of a dimension error, a conner error, an uncut width and a kerf.

• International Journal of Contents
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• v.10 no.1
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• pp.23-28
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• 2014

When developing a classifier using various objective functions, it is important to compare the performances of the classifiers. Although there are statistical analyses of objective functions for classifiers, simulation results can provide us with direct comparison results and in this case, a comparison criterion is considerably critical. A Receiver Operating Characteristics (ROC) graph is a simulation technique for comparing classifiers and selecting a better one based on a performance. In this paper, we adopt the ROC graph to compare classifiers trained by mean-squared error, cross-entropy error, classification figure of merit, and the n-th order extension of cross-entropy error functions. After the training of feed-forward neural networks using the CEDAR database, the ROC graphs are plotted to help us identify which objective function is better.

• Journal of Mechanical Science and Technology
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• v.15 no.6
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• pp.743-751
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• 2001

A Prototype reaction wheel, named the Hankuk Aviation University (HAU) reaction wheel, has been developed for KAISTSAT satellite series. Torque and force disturbances are inherent in reaction wheels, and thus the force and torque characteristics should be examined for every newly developed reaction wheel. The torque and force disturbance noises in the prototype HAU reaction wheel are measured with a torque-measuring table developed for the present study. A new measuring procedure based on a simple principle is applied for the measurements. The frequency characteristics of the torque and force noises are analyzed by examining the power spectral density. The effect of the torque noise on the attitude stability is also examined through numerical simulations with a single-axis attitude model. The noise-induced attitude error and jitter and found to be well below the specified error limits for the KAISTSAT satellite series.