• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2003.05a
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• pp.341-344
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• 2003

There communicates using tire supersonic waves in tire underwater, that is different from tire ground that use tire propagation. Because using Law frequency to come under tire waves, bandwidth that is able to communicate is very smaller that tire mobile communication of tire ground. Also, The channel environment changes rapidly in tire shallow underwater than tire ground. Due to such a reason, data transmission technic that is able to tire maximum application to restricted bandwidth and tire signal processing technics that is able to conquer tire rapid changes of tire channel environment are being used. Algorithm is used at tire application of these technic has a lot of tire calculating quantity. So this research reveals small bulk and equal performance using one DSP chip and then implements QPSK transmitter, that uses SHARC DSP of Analog Device company, for tire underwater supersonic waves communication rapidly decrease tire calculating quantity.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2003.05a
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• pp.109-114
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• 2003

Wireless communication systems are inevitable for efficient underwater activities. Because of the poor propagation characteristics of light and electromagnetic waves, acoustic waves are generally used for the underwater wireless communication. Although there are many kinds of information type, visual images take an essential role especially for search and identification activities. For this reason, we developed an acoustic-based underwater image transmission system under a dual use technology project supported by MOCIE (Ministry of Commerce, Industry and Energy). For the application to complicated and time-varying underwater environments all-digital transmitter and receiver systems are investigated. Array acoustic transducers are used at the receiver, which have the center frequency of 32kHz and the bandwidth of 4kHz. To improve transmission speed and quality, various algorithms and systems are used. The system design techniques will be discussed in detail including image compression/ decompression system, adaptive beam- forming, fast RLS adaptive equalizer, ${\partial}/4$ QPSK (Quadrilateral Phase Shift Keying) modulator/demodulator, and convolution coding/ Viterbi. Decoding.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.7 no.2
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• pp.128-138
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• 1996

In this paper, the Doppler phase error due to the relative velocity between a satellite and the earth station in communications using a low earth orbit mobile satellite is detected. The performance of BPSK system in the presence of Rician fading channel environment with Doppler phase error, inter- ference and noise is compared with that of the system disturbed by Doppler phase error and noise only, And adopted coding techniques are Hamming, BCH, RS and convolution codes. The expression of error rate performance of BPSK system is derived as the type of complementary error function. The main conclusion that can be drawn from this analysis is that Rician fading channel environment with Do- ppler phase error and interference, noise effect yields severe performance degradation then Doppler phase error and noise effect in satellite communication channel. The conclusion can be drawn from this analysis is that using coding technique then noncoding. And using the numerical calculation, we give a quantitative insight how much the satellite communication channel parameters degrade the system per- formance. Furthermore it is shown that an appropriate transmission power control for the performance enhancement is beneficial to the new satellite communication system planning.

• Korean Journal of Cognitive Science
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• v.12 no.1_2
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• pp.77-89
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• 2001

Applying perceptual hierarchy of facial feature points, a neural network model for recognizing facial expressions was designed. Input data were convolution values of 150 facial expression pictures by Gabor-filters of 5 different sizes and 8 different orientations for each of 39 mesh points defined by MPEG-4 SNHC (Synthetic/Natural Hybrid Coding). A set of multiple regression analyses was performed with the rating value of the affective states for each facial expression and the Gabor-filtered values of 39 feature points. The results show that the pleasure-displeasure dimension of affective states is mainly related to the feature points around the mouth and the eyebrows, while a arousal-sleep dimension is closely related to the feature points around eyes. For the filter sizes. the affective states were found to be mostly related to the low spatial frequency. and for the filter orientations. the oblique orientations. An optimized neural network model was designed on the basis of these results by reducing original 1560(39x5x8) input elements to 400(25x2x8) The optimized model could predict human affective rating values. up to the correlation value of 0.886 for the pleasure-displeasure, and 0.631 for the arousal-sleep. Mapping the results of the optimized model to the six basic emotional categories (happy, sad, fear, angry, surprised, disgusted) fit 74% of human responses. Results of this study imply that, using human principles of recognizing facial expressions, a system for recognizing facial expressions can be optimized even with a a relatively little amount of information.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.4 no.3
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• pp.517-526
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• 2000

In this paper, we propose the trellis coded spread spectrum communication system with one channel signal selection of the subset by the PN code. This paper proposes the Viterbi decoder that have the squared Euclidean distance of the order phase difference as well as 1st order phase difference as the branch metrics by using the multiple symbol detection method. TCM method was developed to overcome limited power and bandwidth efficiently in digital communication. we multiply one of convolution code's output data to PN code for applying TCM to the spread spectrum. We investigated the performance of the direct sequence/spread spectrum communication system with trellis coded modulation. In this system, we could improved the coding gain in the spread spectrum.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2007.06a
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• pp.754-757
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• 2007

In this paper, we present an implementation and it's real-sea test of an underwater acoustic data communication system, which allows the system to reduce complexity and increase robustness in time variant underwater environments. For easy adaptation to complicated and time-varying environments of the ocean, all-digital transmitter and receiver systems were implemented. For frame synchronization the CAZAC sequence was used, and QPSK modulation/ demodulation method with carrier frequency of 25kHz and a bandwidth of 5kHz were applied to generate 10kbps transmission rate including overhead. To improve transmission quality, we used several techniques and algorithms such as adaptive beamforming, adaptive equalizer, and convolution coding/Viterbi decoding. for the verification of the system performance, measurement of BER has been done in a very shallow water with depth of 8m at JangMok, Geoje. During the experiment, image data were successfully transmitted up to about 7.4km.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.6 no.2
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• pp.175-180
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• 2002

In this paper, the system performace with the convolution rode using a Viterbi decoding and the one tap LMS(Least Meam Square) equalizer applied to the OFDM(Orthogonal Frequency Division Multiplexing) system, is analyzed through computer simulation. DMRS(Digital Microwave Radio System)is modeled as Rummler fading channel. In Simulation result, we known that the coding system improved about 3.6dB~10.5dB when BER is 10 $^3$and b is 0.1~0.2 in case of 16QAM(Qurdrature Amplitude Modulation). Also, we known that was improved about 19.7dB when the b is 0.1 and was demanded about 10.5dB when the b is 0.2 in case of 64QAM. we known that the soft decision improved about 2~0.9dB when the b is 0.1~0.2 in case of 16QAM and about 3.3~7.8dB in case of 64QAM. In the equalizer system, efficiency improved from the case of that Eb/No is more than 13dB.

• The Journal of the Korea institute of electronic communication sciences
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• v.17 no.3
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• pp.529-536
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• 2022

In the past two years, Severe Acute Respiratory Syndrome Coronavirus-2(SARS-CoV-2) has been hitting more and more to people. This paper proposes a novel U-Net Convolutional Neural Network to classify and segment COVID-19 lung CT images, which contains Sub Coding Block (SCB), Atrous Spatial Pyramid Pooling(ASPP) and Attention Gate(AG). Three different models such as FCN, U-Net and U-Net-SCB are designed to compare the proposed model and the best optimizer and atrous rate are chosen for the proposed model. The simulation results show that the proposed U-Net-MMFE has the best Dice segmentation coefficient of 94.79% for the COVID-19 CT scan digital image dataset compared with other segmentation models when atrous rate is 12 and the optimizer is Adam.

• International Journal of Computer Science & Network Security
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• v.22 no.10
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• pp.73-82
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• 2022

Early detection continues to be the mainstay of breast cancer control as well as the improvement of its treatment. Even so, the absence of cancer symptoms at the onset has early detection quite challenging. Therefore, various researchers continue to focus on cancer as a topic of health to try and make improvements from the perspectives of diagnosis, prevention, and treatment. This research's chief goal is development of a system with deep learning for classification of the breast cancer as non-malignant and malignant using mammogram images. The following two distinct approaches: the first one with the utilization of patches of the Region of Interest (ROI), and the second one with the utilization of the overall images is used. The proposed system is composed of the following two distinct stages: the pre-processing stage and the Convolution Neural Network (CNN) building stage. Of late, the use of meta-heuristic optimization algorithms has accomplished a lot of progress in resolving these problems. Teaching-Learning Based Optimization algorithm (TIBO) meta-heuristic was originally employed for resolving problems of continuous optimization. This work has offered the proposals of novel methods for training the Residual Network (ResNet) as well as the CNN based on the TLBO and the Genetic Algorithm (GA). The classification of breast cancer can be enhanced with direct application of the hybrid TLBO- GA. For this hybrid algorithm, the TLBO, i.e., a core component, will combine the following three distinct operators of the GA: coding, crossover, and mutation. In the TLBO, there is a representation of the optimization solutions as students. On the other hand, the hybrid TLBO-GA will have further division of the students as follows: the top students, the ordinary students, and the poor students. The experiments demonstrated that the proposed hybrid TLBO-GA is more effective than TLBO and GA.

• Journal of Navigation and Port Research
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• v.39 no.4
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• pp.293-297
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• 2015

Underwater acoustic communications has been limited use for military purposes in the past. However, the fields of underwater applications expend to detection, submarine and communication in recent. The excessive multipath encountered in underwater acoustic communication channel is creating inter symbol interference, which is limiting factor to achieve a high data rate and bit error rate performance. To improve the performance of a received signal in underwater communication, many researchers have been studied for channel coding scheme with excellent performance at low SNR. In this paper, we applied BCJR decoder based ( 2,1,7 ) convolution codes and to compensate for the distorted data induced by the multipath, we applying the turbo equalization method. Through the underwater experiment on the Gyeungcheun lake located in Mungyeng city, we confirmed that turbo equalization structure of BCJR has better performance than hard decision and soft decision of Viterbi decoding. We also confirmed that the error rate of decoder input is less than error rate of $10^{-1}$, all the data is decoded. We achieved sucess rate of 83% through the experiment.