• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2011.06a
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• pp.66-67
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• 2011

항로를 횡단하여 건설되는 교량이 증가하고 해상교통의 증가에 비례하여 항로의 혼잡도가 증가하는 만큼 선박과 교량의 충돌우려가 커지고 있다. 선박과 교량의 충돌은 단순 접촉사고가 아닌 재난급 사고의 개연성이 크다. 직접 손괴를 일으키는 큰 충돌이 아니더라도 선박과 교각의 충격진동에 의하여 교량상판이 균형을 잃고 연쇄 붕괴하는 일이 종종 발생하여 많은 인명의 손실이 발생하고 있기 때문이다. 적정 교각 폭, 교각의 시인성 증진을 위한 표지와 등화의 설치 및 점등방법 등의 환경 여건 개선, 충돌방지공의 효과 검토, 교량 통과전 사전 점검사항, 교량 부근에서 선박의 조종성 유지방안, 예선의 효과 연구, 관제기법과 안전규정, 불가피한 충돌이나 접촉의 경우 손실 감소대책과 충돌방지공의 효과 등 다각적인 연구가 필요하다. 면피용 탁상이론을 배제하고 현장실무의 경험을 바탕으로 실효적인 방안을 제시하고자 한다.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.61 no.4
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• pp.234-238
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• 2012

This paper proposes a multiplexed space-frequency block coding (SFBC) technique for single-carrier modulation with frequency domain equalization. Multiplexed space-frequency block coding technique for single-carrier modulation uses multiple groups of two transmitters and suppresses the interference signals of other SFBC groups at the receiver. In this paper, we reconfigure transmit signals to adapt them for multiplexed SFBC for single-carrier modulation with frequency domain equalization and receiver structures and propose a structure for transmitter and receiver, show its performance is better than the traditional algorithm by simulations.

• Journal of IKEEE
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• v.14 no.4
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• pp.283-290
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• 2010

This study is on the design of 10Gbps CMOS receiver circuits for fiber-optic communication. The receiver is made up of a photodiode, a transimpedance amplifier, a limiting amplifier, an equalizer, a clock and data recovery loop circuit, and a demultiplexer or demux with some auxiliary circuits including I/O circuits. Various wideband or high-speed circuit techniques are harnessed to realize a feasible, effective, and reliable receiver for a SONET fiber-optic standard, OC-192.

• Phonetics and Speech Sciences
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• v.9 no.2
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• pp.77-83
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• 2017

We propose a new method to reduce emotion recognition errors caused by variation in speaker characteristics and speech rate. Firstly, for reducing variation in speaker characteristics, we adjust features from a test speaker to fit the distribution of all training data by using the histogram equalization (HE) algorithm. Secondly, for dealing with variation in speech rate, we augment the training data with speech generated in various speech rates. In computer experiments using EMO-DB, KRN-DB and eNTERFACE-DB, the proposed method is shown to improve weighted accuracy relatively by 34.7%, 23.7% and 28.1%, respectively.

• Proceedings of the KIPE Conference
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• 2015.07a
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• pp.447-448
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• 2015

지연 등화기(Delay Equalizer) 또는 위상 필터(Phase Filter)라고도 불리는 전역 통과 필터(All Pass Filter)는 주파수의 변화와 관계없이 위상만을 변화 시키는 시간 지연 장치(Time Delay Device)이다. 모든 주파수에서 진폭의 이득이 '0' 또는 일정하지만, 위상의 특성만을 개선하기 위해 사용되는 위상 필터 이다. 본 논문은 이와 같은 전역 통과 필터(APF)의 특성을 이용하여 순시 유효 전력(Active Power) 및 순시 무효 전력(Reactive Power)의 측정 방법에 대하여 연구하였다. 전역 통과 필터(APF)의 좌표변환을 사용하여, 필터에서의 정보를 통한 유효 전력과 무효 전력 측정이 가능하다. 따라서 본 논문에서는 시뮬레이션을 통해 그 타당성을 검증하였다.

• MALSORI
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• no.60
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• pp.145-164
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• 2006

This paper proposes class histogram equalization (CHEQ) to compensate noisy acoustic features for robust speech recognition. CHEQ aims to compensate for the acoustic mismatch between training and test speech recognition environments as well as to reduce the limitations of the conventional histogram equalization (HEQ). In contrast to HEQ, CHEQ adopts multiple class-specific distribution functions for training and test environments and equalizes the features by using their class-specific training and test distributions. According to the class-information extraction methods, CHEQ is further classified into two forms such as hard-CHEQ based on vector quantization and soft-CHEQ using the Gaussian mixture model. Experiments on the Aurora 2 database confirmed the effectiveness of CHEQ by producing a relative word error reduction of 61.17% over the baseline met-cepstral features and that of 19.62% over the conventional HEQ.

• Journal of the Institute of Convergence Signal Processing
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• v.19 no.3
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• pp.139-146
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• 2018

Underwater acoustic communication can be applied to various area such as scientific, commercial and military survey using Autonomous Underwater Vehicles and Unmanned Underwater Vehicles. Underwater communication is studying very actively by advanced country like United States. But differ from wireless communication in the air, underwater acoustic communication has some difficult problems, ISI(Inter Symbol Interference) due to multipath and limit of transmission bandwidth due to slow propagation of sound wave. In this paper, SC-FDE and OFDM transmission system for the cancellation of ISI in conjunction with underwater acoustic channel modeling are applied to the underwater simulation of communication. The performance of these methods in the simulation guide to possibility of adopting in underwater acoustic communication algorithm. For this purpose, we compare SER performance of SC-FDE with that of OFDM for modelled underwater channel. Underwater channel is generated by Bellhop model. Simulation results show above 5dB SNR gain at 10-3 SER. And it demonstrate SC-FDE is efficient method for underwater acoustic communication.

• The Journal of the Acoustical Society of Korea
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• v.39 no.1
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• pp.8-15
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• 2020

In this paper, we propose a frame synchronization algorithm for robust to the combined effects of large Doppler fluctuations and extended, time-varying multipath in the underwater acoustic communication. From the algorithm, we can recover a high timing error which is occurred from an acoustic propagation delay and uncertainty of oscillator between transmitter and receiver. In order to verify the performance of the synchronization algorithm, the lake trial results are used. The lake experiments are performed in a Gyeongcheonho located in Mungyeong-si, Gyeongsangbuk-do. We can see that the start position of frame is adjusted after the frame synchronization while the receiver moving.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.9
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• pp.1688-1695
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• 2016

Underwater communication has multipath error because of reflection by sea-level and sea-bottom. The multipath of underwater channel causes signal distortion and error floor. The excessive multipath encountered in underwater communication channel creates inter symbol interference, which is a limiting factor to achieve a high data rate and bit error rate performance. Therefore, to increase throughput efficiency and improve performance, this paper consider FTN (Faster-than-Nyquist) signalling based on turbo equalization. FTN signalling is a technique of transmitting information at a rate higher than the allowed Nyquist limit. This paper presented efficient decoder structure of FTN transmission in the environment of multipath underwater channel and we compare the performance between FTN method and conventional punctured method in lake experimentation. As a results of lake experiment, we confirmed FTN method based on turbo equalization is applicable and efficiency in underwater communication.

• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.4
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• pp.12-19
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• 2016

The monitoring system in railway is under study to forecast any derailment and accident by defect of train. Because the monitoring system is composed of wireless sensor network based on ZigBee-communication between inside and outside of train, the study for wireless channel analysis is required. Especially, if multipath delay profile exist in the channel, the equalizer and channel estimator can be required for preventing receiver performance degradation. Therefore, we analyzed the wireless channel in train environment using measured data and, proposed the channel estimation method through the characterisitic of chip code, under the consideration of the channel characteristics in train. To show the performance of proposed method, we demonstrate the performance by mean square error(MSE), computational complexity and bit error rate(BER).