• Proceedings of the KSR Conference
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• 2008.11b
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• pp.1006-1011
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• 2008

The objective of this study is the developement of real time automatic dynamic measurement using high accuracy digital datalogger for safety and maintence of railway construction sites. For the replacement of current 16 bit analog/digital converter, Digital datalogger system using 24 bit analog/digital converter is studied for the first time with in a country. Therefore data communication method and analyzing program of automatic measurement data is developed for the automatic high accuracy digital datalogger system. The results of this study will be using real time automatic dynamic measurement of railway structures.

• The Journal of the Acoustical Society of Korea
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• v.38 no.4
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• pp.371-377
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• 2019

In this paper, we present the sea trial results of long distance underwater acoustic communication in the East Sea, October 2018. One transmitter and sixteen vertical array receivers were used to collect underwater acoustic communication signals, and the maximum distance between the transmitter and the receiver was 90 km. Information was transmitted by BFSK (Binary Frequency Shift Keying) and BCSK (Binary Chirp Shift Keying) method, which are typical digital frequency modulation techniques. Experimental results show that there is no error in all cases at the transmission distance of 60 km, and BFSK and BCSK have average uncoded bit error rate of 0.0197 and 0.0007 respectively without channel coding at 90 km transmission distance.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 1987.04a
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• pp.52-55
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• 1987

In tihis paper an improved matching method using subtemplate of moving region and 3-step search algorithm is proposed It reduces heavy computational load of the conventional method. The proposed method is applied to an automatic target tracker using high speed 16 bit microprocessor in order to track one moving target in real time. Expericmental results show that the proposed method has better performance over the conventional methodin spite of greately reducing the computational load, even in came complex background.

• The Journal of the Acoustical Society of Korea
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• v.16 no.3E
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• pp.44-49
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• 1997

In this paper, we propose an adaptive encoding method of fixed codebook in CELP coders and implement an adaptive fixed code exited linear prediction(AF-CELP) speech coder. AF-CELP exploits the fact that the fixed codebook contribution to speech signal is also periodic like the adaptive codebook (or pitch filter) contribution. By modeling the fixed code book with the pitch lag and the gain from the adaptive codebook, AF-CELP can be implemented at low bit rates as well as low complexity. Listening tests show that a 6.4 kbit/s AF-CELP has a comparable quality to the 8 kbit/s CS-ACELP in background noise conditions.

• Proceedings of the Acoustical Society of Korea Conference
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• 1995.06a
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• pp.137-140
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• 1995

In the paper, CDMA's vocoder algorithm, QCELP, was analyzed. And, 16-bit programmable DSP core for QCELP was designed. When it is used two MACs in DSP, we can implement low-power DSP and estimate decrease of parameter computation speed. Also, we implemented in FIFO memory using register file to increase the access time of the data. This DSP was designed using logic synthesis tool, COMPASS, by top-down design methodology. Therefore, it is possible to cope with rapid change at mobile communication market.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.9A
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• pp.1422-1430
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• 2000

S(Synchronous)-CDMA is a new cable modem technology applicable to the upstream channel for high speed multimedia communication using CATV networks. In this paper we analyze the transmitting and receiving process of S-CDMA scheme based on Terayon patent and derive bit error probability of S-CDMA and TDMA scheme in the $\varepsilon$-mixture impulse noise model which appropriately reflects impulse noise characteristics of upstream channel by using various parameters. This analysis results are a good match with the simulation results. We also compare Eb/No gain performance of S-CDMA with TDMA in 16, 32, 64, QAM.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.16 no.7
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• pp.651-662
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• 1991

An improved modular multiplication algorithm for RSA type public key cryptosystem and its application to a serial communication cricuit are presented. Correction on a published fast modular multiplication algorithm is proposed and verified thru simulation. Cryptosystem for RS 232C communication protocol isdesigned and prototyped for low speed data exchange between computers. The system adops the correct algoroithm and operates successfully using a small size key.

• Proceedings of the IEEK Conference
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• 2008.06a
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• pp.705-706
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• 2008

The feature of 6LoWPAN is the capability of the dynamic assignment of 16bit short addresses. By using this dynamically assigned short address, a hierarchical routing is employed. In case of node failure, this hierarchical routing don't support a technique for path recovery. So, this paper proposes the path recovery technique for hierarchical routing over 6LoWPAN.

• JSTS:Journal of Semiconductor Technology and Science
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• v.16 no.3
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• pp.274-286
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• 2016

This paper presents a 4-channel multi-rate vertical-cavity surface-emitting laser (VCSEL) driver. In order to keep the output power constant with respect to the process, voltage, temperature (PVT) variations, this research proposes automatic power and magnitude. For the fast settling time, the high-speed 10-bit time-interleaved Flash-successive approximation analog to digital converter (Flash-SAR ADC) is proposed and shared for automatic power and magnitude calibration to reduce the die area and power consumption. This chip is fabricated using $0.13-{\mu}m$ CMOS technology and the die area is $4.2mm^2$. The power consumption is 117.84 mW per channel from a 3.3 V supply voltage at 10 Gbps. The measured resolution of bias /modulation current for APC/AMC is 0.015 mA.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.4 no.3
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• pp.627-633
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• 2000

In this paper, the polyphase filter which has micro ripple characteristic in the passband is proposed. This filter consists of the digital all-pass filter of parallel structure and it is the half-band filter with all zeros in unit circle. To approach easily in designing hardware, we determined the coefficients to the 16bit 1.15 format. To evaluate the performance of this filter, we analyzed the phase characteristic in each branch and each filter with small coefficients. Also, we simulated the phase characteristic of passband and stopband, group delay. As the result, we obtained the micro ripple characteristic and linear phase in the passband.