• Proceedings of the IEEK Conference
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• 2004.06a
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• pp.147-150
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• 2004

In this paper, we propose a reduced-state sequence estimation (RSSE) for trellis coded modulation (TCM) in OFDM with two-stage IDFT/ DFTs, MMSE-LE, and interleaving on frequency selective Rayleigh fading channels. The Viterbi algorithm (VA) is used to search for the best path through the reduced-state trellis combined with equalization and TCM decoding. Computer simulations confirm the bit error probability of the proposed scheme.

• Journal of Industrial Technology
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• v.17
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• pp.11-20
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• 1997

This paper deals with the study on the cutting characteristics in ball endmilling process. First of all, the effects of the geometric cutting conditions such as the cutting speed, feedrates and the path interval on the surface integrity were evaluated by the analytical and the experimental approaches. Secondly, the cutting mechanism model was developed to predict the cutting force accurately. Prediction of cutting force make it possible to predict the shape error, estimate system stability and build the reliable adaptive control system. A large amount of experimental set are performed to show the validities of the proposed theories and to investigate the effect of cutting geometry such as rubbing effects, burr effects and etc.

• Transactions of the Korean Society of Mechanical Engineers
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• v.12 no.2
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• pp.389-396
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• 1988

Microprocessor-based software DDA interpolator is developed and applied to two axis contouring control of X-Y table. Developed assembly program is composed of feedrate, linear and circular DDA interpolation routines. Reference-pulse type of open-loop stepping motor control system in which the micro-computer produces a sequence of reference pulses for each axis of motion is adopted. To test performance of the developed program, X-Y table drive system based on stepping motor and shaft encoder is designed. Conturing error of the system in linear and circular path is within .+-. 0.2mm under start stop pulse rate of stepping motor.

• Journal of Advanced Marine Engineering and Technology
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• v.29 no.5
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• pp.560-570
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• 2005

In this paper, we discuss the tracking system for a wheelchair which can follow the path of a human target such as a nurse in hospital. The problem of human tracking is that it requires recognition of feature as well as the tracking of human positions. For this purpose the use of a high cost visual sensor such as laser finder or streo camera makes the tracking a high cost additional expense. This paper proposes the tracking system uses a low cost infrared range-finder and CCD camera, The Infrared range-finder and CCD camera can create a target candidate through each target recognition algorithm. and this information is fused in order to reduce the uncertainties of a target decision and correct the positional error of the human. The effectiveness of the proposed system is verified through experiments.

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.1306-1311
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• 2004

The performance test apparatus of liquid-phase plate heat exchanger was installed and the computer program for design was developed in this study. The detail temperature distribution of hot and cold fluids in each path of heat exchanger was calculated by numerical method and the correlation for the heat transfer coefficient was defined. The heat transfer coefficients were measured using the working fluids of water and glycerine to investigate the effect of fluid viscosity. The measured heat transfer coefficients were compared with the calculated values obtained from the computer program and it was shown that error of the calculated values was generally less than 5%.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2002.04a
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• pp.227-232
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• 2002

This paper presents an algorithm for general 2D and 3D NURBS interpolation and deals with command generation for 3 axes milling machining, including the feedrate control in order to meet two limitations, a geometrical accuracy and a dynamic restriction. Both of the maximum chordal error and the maximum acceleration specified by machine parameter lead to limit the allowable feedrate on the curvature of NURBS tool path. So, motion commands at every sampling time are continuously generated by those two limitations and programmed feedrate. Simulation results of interpolating several NURBS curves show that proposed NURBS algorithm is favorable in the machining free-form curve

• Journal of Korea Society of Digital Industry and Information Management
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• v.11 no.3
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• pp.45-51
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• 2015

In this paper, we discuss the belief propagation decoding algorithm for polar codes. The performance of Polar codes for shorter lengths is not satisfactory. Motivated by this, we propose a novel technique to improve its performance at short lengths. We showed that the probability of messages passed along the factor graph of polar codes, can be increased by multiplying the current message of nodes with their previous message. This is like a feedback path in which the present signal is updated by multiplying with its previous signal. Thus the experimental results show that performance of belief propagation polar decoder can be improved using this proposed technique. Simulation results in binary-input additive white Gaussian noise channel (BI-AWGNC) show that the proposed belief propagation polar decoder can provide significant gain of 2 dB over the original belief propagation polar decoder with code rate 0.5 and code length 128 at the bit error rate (BER) of $10^{-4}$.

• Proceedings of the Korean Society for Bioinformatics Conference
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• 2001.08a
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• pp.11-35
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• 2001

For the last twenty years fragment assembly in DNA sequencing followed the "overlap - layout - consensus"paradigm that is used in all currently available assembly tools. Although this approach proved to be useful in assembling clones, it faces difficulties in genomic shotgun assembly: the existing algorithms make assembly errors and are often unable to resolve repeats even in prokaryotic genomes. Biologists are well-aware of these errors and are forced to carry additional experiments to verify the assembled contigs. We abandon the classical “overlap - layout - consensus”approach in favor of a new Eulerian Superpath approach that, for the first time, resolves the problem of repeats in fragment assembly. Our main result is the reduction of the fragment assembly to a variation of the classical Eulerian path problem. This reduction opens new possibilities for repeat resolution and allows one to generate error-free solutions of the large-scale fragment assemble problems. The major improvement of EULER over other algorithms is that it resolves all repeats except long perfect repeats that are theoretically impossible to resolve without additional experiments.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.92-96
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• 2007

Microphone array beamforming method has been recognized as an important aeroacoustic research field and become a standard technique in localizing sound sources. This method also used in flight acoustic measurement, and especially, it is very useful when measure sounds inside the wind tunnel. In measuring sound which is inside the wind tunnel by traditional beamforming method, there are some errors caused by airstream. The speed and the propagation path of the sound changes as it travel through the airstream. This makes the error which the position of sound is changed a little bit to the down stream direction. In this paper, validation test has made about the correction equation for this wind effects of previous researches. And beamforming including shear layer correction was performed about a sound source in the anechoic open-jet windtunnel.

• Communications for Statistical Applications and Methods
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• v.18 no.4
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• pp.495-505
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• 2011

This study performs statistical tests for stability of a long-run relationship in the telecommunication market system by identifying the time path of a recursively estimated cointegration parameter. A dummy variable is used to recover stability for the period that the hypothesis of stable cointegration is rejected, and then a proper cointegrating relation is derived. A dummy variable appears to reflect the structural change in the cointegrating relation according to the analytical results for the error correction term.