• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.11A
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• pp.1138-1145
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• 2007

In wireless communications, chaotic communications have been a field of interest due to its low complexity in hardware implementation and low power consumption in chaotic signal generation. Among the modulation schemes using the chaotic signal, Differential Chaos Shift Keying (DCSK) is a robust non coherent technique. As in the conventional communication systems, chaos-based systems are required to provide reasonable bit error performance in the presence of a narrow-band signal coming from any other systems. The frequency band of this foreign narrow band signal may lie within the bandwidth of the chaos-based systems. This situation may occur when chaotic signal transmission is done in the presence of other conventional communication system. This paper has evaluated the performance of the non coherent differential chaos shift keying (DCSK) system under the presence of conventional non-chaotic transmit reference system. Both systems are assumed to have same data rates. The mathematical expressions for the bit error rate (BER) are derived with computer simulations to verify the analytical results.

• Proceedings of the IEEK Conference
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• 2006.06a
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• pp.77-78
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• 2006

This paper presents a signal quality estimation technique for QAM modulation systems. By making a LUT(Look-up table) putting the number of N enough, we can derive estimated SNR from LUT even though N is small. That is so called MOTM algorithm. In 16-QAM, the distance $d_a$, between adjacent symbols is always invariable, so absolute value of R(the amplitude of signal) minus $d_a$ has a always same signal distribution value. This value does not form a Gaussian shape but, by making a little bit correction, we can make this symmetrical. So, from the received symbol value, by using LUT we can easily derive the estimated SNR. By considering this, we introduce a signal quality estimation technique for QAM schemes. This proposed method can be applicable to high order modulation schemes and wide range of signal to noise ratio.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39A no.6
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• pp.303-309
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• 2014

Chaos communication system can improve a system security due to characteristics of non-periodic, non-predictability, broadband signal and easy implementation. Also, chaos signal is sensitive to initial conditions of chaos map. By these reasons, security of chaos communication system is superior to digital communication system. BER performance of COOK modulation system is better than other chaos modulation systems, even if COOK modulation system uses an asynchronous receiver. However, security and safety of COOK modulated signal are worse than other chaos modulation systems, because information bits can be easily predicted from COOK modulated signal. In this paper, for security improvement of COOK modulated signal, we propose a novel Scrambling COOK modulation system by applying the scrambling method. Conventional COOK modulated signal can be predicted, because chaos signal is generated when data is only 1. However, proposed system cannot be predicted, because chaos signal is generated when data is 0 or 1. Therefore, security and safety of transmitted signal in scrambling COOK modulation system is superior to conventional COOK modulation system.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.2231-2236
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• 2005

CP (Cellular Phone) is currently one of the most attractive technologies and RT (Robot Technology) is also considered as one of the most promising next generation technology. We present a new technological concept named RCP (Robotic Cellular Phone), which combines RT and CP. RCP consists of 3 sub-modules, $RCP^{Mobility}$, $RCP^{Interaction}$, and $RCP^{Integration}$. $RCP^{Interaction}$ is the main focus of this paper. It is an interactive emotion system which provides CP with multi-emotional signal receiving functionalities. $RCP^{Interaction}$ is linked with communication functions of CP in order to interface between CP and user through a variety of emotional models. It is divided into a tactile, an olfactory and a visual mode. The tactile signal receiving module is designed by patterns and beat frequencies which are made by mechanical-vibration conversion of the musical melody, rhythm and harmony. The olfactory signal receiving module is designed by switching control of perfume-injection nozzles which are able to give the signal receiving to the CP-called user through a special kind of smell according to the CP-calling user. The visual signal receiving module is made by motion control of DC-motored wheel-based system which can inform the CP-called user of the signal receiving through a desired motion according to the CP-calling user. In this paper, a prototype system is developed for multi-emotional signal receiving modes of CP. We describe an overall structure of the system and provide experimental results of the functional modules.

• Journal of the Korea Society of Computer and Information
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• v.27 no.2
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• pp.163-170
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• 2022

Currently, as the number of families living with companion animals increases, the demand for information about the health status of companion animals has increased. As the demand for this increases, there is a need for a method to measure respiration and pulse in companion animals. Considering the characteristics of hairy companion animals, we want to measure respiration and pulse signals using BCG, which is different from adsorption ECG. Since this BCG method is made by mixing respiration and pulse signals into one signal, it is necessary to separate the respiration signal waveform and the pulse signal waveform from one signal waveform. In this paper, a wearable device for BCG measurement was implemented to measure the signal, and a method of separating the signal input from the BCG wearable device into a respiration signal and a pulse signal was proposed.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.12
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• pp.197-204
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• 2013

In this paper, we propose a new method for artificial bandwidth extension of narrow-band signal in frequency domain. In the proposed method, a narrow-band signal is decomposed into excitation signal and spectral envelope, which are extended independently in frequency domain. The excitation signal is extended such that low-band harmonic structure is maintained in high band, and the spectral envelope is extended based on sub-band energy using NMF. Finally, the spectral phase is determined based on signal correlation between frames in time domain, resulting in the final wide-band signal. The subjective evaluation verified that the wide-band signal generated by the proposed method has a higher quality than the original narrow-band signal.

• Proceedings of the Korea Society of Information Technology Applications Conference
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• 2005.11a
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• pp.339-342
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• 2005

In order to support ultrawide-band signal generation for low rate WPAN, several types of signal generation mechanisms are suggested such as Chaos, Impluse, and Chirp signals by the activity of IEEE 802.15.4a. The communication system applied chaos theory may have ultrawide-band characteristics with spread spectrum and immunity from multipath effect. In order to use the advantage of chaotic signal generation, we introduce the system implementation of communication and networking systems with the chaos UWB signal. This system may be composed of mainly three parts in hardware architecture : RF transmission with chaotic signal generation, signal receiver using amplifiers and filters, and 8051 & FPGA unit. The most difficult part is to implement the chaotic signal generator and build transceiver with it. The implementation of the system is devidced into two parts i.e. RF blocks and digital blocks with amplifiers, filters, ADC, 8051 processor, and FPGA. In this paper, we introduce the system block diagram for chaotic communications. Mainly the RF block is important for the system to have good performance based on the chaotic signal generator. And the main control board functions for controlling RF blocks, processing Tx and Rx data, and networking in MAC layer.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.4 no.1
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• pp.39-45
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• 2011

In this paper, the design method of portable signal analysis system is proposed and the hardware module is implemented for operation of base stations based on a common platform for mobile WiMax. The new signal analysis method is implemented as two modules; a broadband RF module and a DSP based digital signal analysis module. The RF module performs the RF-IF down conversion and gain control. And the digital module measure the base staion signal. The differences of performance are insignificant in the experiment results performed through the comparison of other fixed-large system and proposed system.

• Journal of the Korean Society of Safety
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• v.24 no.3
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• pp.65-70
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• 2009

In-vehicle route guidance information(RGI) systems have been developed with the advancement of the information and communication technologies. However, the RGI is provided by a pre-determined option, drivers occasionally pass the target intersection owing to non- or late- recognizing it. The purpose of this experiment is to examine the position of driver's tum signal operation and intersection recognition approaching at the target intersection which is difficult to identify as a preliminary research on developing the additional RGI connecting with the tum signal control. The field experiment was conducted to measure distances of the turn signal operation and intersection recognition from the target intersection according to driving lanes and landmarks at adjacent intersection. And, glance behavior to the car navigation display was evaluated by using an eye camera. The results indicate that drivers operate the turn signal after confirming a landmark in the case of the intersection with it. However, most case of driving, drivers operate the tum signal at 40 to 50m before coming to the target. To provide the additional RGI, when drivers do not operate the tum signal approaching at the target intersection based on the results, is expected to improve the traffic safety and the comfort for drivers.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.4
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• pp.537-543
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• 2003

Transient vibration generated by developing localized fault in gear can be used as indicators in gear fault detection. This vibration signal suffers from the background noise such as gear meshing frequency and its harmonics and broadband noise. Thus in order to extract the information about the only gear fault from the raw vibration signal measured on the gearbox this signal is processed to reduce the background noise with many kinds of signal-processing tools. However, these signal-processing tools are often very complex and time waste. Thus. in this paper. we propose a novel approach detecting the damage of gearbox and analyzing its pattern using the raw vibration signal. In order to do this, the residual signal. which consists of the sideband components of the gear meshing frequent) and its harmonics frequencies, is extracted from the raw signal by the power spectral density (PSD) to obtain the information about the fault and is used as the input data of the artificial neural network (ANN) for analysis of the pattern of gear fault. This novel approach has been very successfully applied to the damage analysis of a laboratory gearbox.