• Journal of the Institute of Electronics Engineers of Korea TC
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• v.39 no.8
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• pp.1-6
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• 2002

In this paper, we considered the CDMA/TDD system suitable for high-speed packet data transmission such as Internet and multimedia services, and a sequential decoding scheme which enables fast decoding and retransmission requirement. In addition, we Proposed an improved FANO algorithm, which adopts the competition path in order to reduce the number of revisit nodes. The conventional FANO algorithm suffered from the drawback of much more revisit nodes. Furthermore, we analyzed the performance of the CDMA/TDD system with the sequential decoding scheme we proposed over multipath channel.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.47 no.7
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• pp.102-108
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• 2010

In this paper, we analyse the frequency diversity of BICM-OFDM with extended interleaving. The extended interleaving is an interleaving which is added to the existing BICM-OFDM system to extends the interleaving depth by times to the previous interleaving depth. Using the extended interleaving, the diversity order of the proposed system over -tap frequency selective channels is increased from min($d_{free}$, L) to min($d_{free}$, KL), where $d_{free}$ is minimum Hamming distance of the convolutional code. Simulation is also performed to show that the performance of the proposed system is better than that of the existing system even if the channel is an on-off channel in which the number of multi-paths is varying.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.6C
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• pp.570-579
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• 2003

The performance of turbo codes is investigated in the direct detection optical PPM channel. We assume that an ideal photon counter is used as an optical detector and that the channel has background noise as well as quantum noise. Resulting channel model is M-ary PPM Poisson channel. We propose the structure of the transmitter and receiver for applying turbo codes to this channel. We also derive turbo decoding algorithm for the proposed coding system, by modifying the calculation of the branch metric inherent in the original turbo decoding algorithm developed for the AWGN channel. Analytical bounds are derived and computer simulation is performed to analyze the performance of the proposed coding scheme, and the results are compared with the performances of Reed-Solomon codes and convolutional codes.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2013.10a
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• pp.41-44
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• 2013

As appearance of high-quality service such as UDTV application, high-speed and high-capacity communication services are required. For this, communication systems increase the data processing speed and use various error correction techniques. In this paper, we implement the Viterbi decoder applied in 1000BASE-T with 4 pairs UTP cable. The minimum operating speed of the Viterbi decoer should be more than 125 MHz because 125 MHz PAM-5 signal is transmitted on each pair of cables in 1000BASE-T. To do this, we implement the decoder by using the pipeline and parallel processing and verify the operation with 125 MHz by using a logic analyzer. Finally, we will show that the decoder recovers the original data for the added random error data.

• The KIPS Transactions:PartC
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• v.13C no.1 s.104
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• pp.75-82
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• 2006

In this paper, a space-frequency coded orthogonal frequency division multiplexing (SFC-OFDM) scheme with dual Viterbi decoder is proposed and analyzed. Here, two independent half-rate OFDM symbols are generated after convolutional coding of the binary source code. A dual Viterbi decoder is exploited to decode the demodulated sequences independently in the receiver, and their path metrics are compared. Accordingly, the recovered binary data in the proposed scheme are composed of the combination of the sequences having larger path metrics while those in a conventional system are simply the output of single Viterbi decoder. As a result, the proposed SFC-OFDM scheme has a better performance than the conventional one for all signal-to-noise power ratio.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.5
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• pp.1083-1096
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• 1997

To implement satellite B-ISDN/ATM network, it needs to gurantee reliable transport via satelite in the poor BER environment. So, it requires to use channel coding (FEC:Forward Error Correction) schemes for improvement of BER performance, but these coding effects evoke burst errors and degradation of the QoS. Therefore we have to investigate new algorithm that compensates these weaknesses. We consider convolutional coding and concatenated coding among FEC schemes as FEC for satellite transmission and choose different compensational algorithm by the error characteristics of the using type of FEC. In using concatenated coding, this paper proposes the satellite system structure for interconnection to the terrestrial network and proposes the channel coding algorithm for improvement of transmission performances. We execute performance evaluation of the proposed algorithm by computer simulation. In detail, we propose 4 types of application ATM cell to the block coding(Reed-Solomon) and propose the new 55 byte ATM cell that enforces the error correction capability of cell header by the BCH coding. Then we propose the outer interleaverand the cell unit interleaver that evoke maximum coding effect of BCH code.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.6A
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• pp.773-781
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• 2000

The average bit error rate of wideband CDMA in forward link is evaluated for frequency and timing errors in multipath Rayleigh fading channel. The channel BER is evaluated analytically and information BER is investigated with simulation. The performance degradation due to the code/frequency synchronization errors was obtained through simulation for particular two coding schemes - convolutional codes and turbo codes. The results show 1dB degradation due to Tc/4 timing error and 0.5dB degradation due to 50Hz frequency error, for both coding schemes.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.5 no.9
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• pp.1528-1543
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• 2011

With increasing the using of wireless technologies in essential fields such as the medical application, this paper proposes different scenarios for the transmission of images over wireless networks. The paper uses the IEEE ZigBee 802.15.4 for applying the proposed schemes. It is a Wireless Personal Area Network (WPAN). This paper presents a novel chaotic interleaving scheme against error bursts. Also, the paper studies the proposed interleaver with the convolutional code with different constraint lengths (K). A comparison study between the standard scheme and proposed schemes for image transmission over a correlated fading channel is presented. The simulation results show the superiority of the proposed chaotic interleaving scheme over the traditional schemes. Also, the chaotic interleaver packet-by-packet basis gives a high quality image with (K=3) and reduces the need for the complex encoder with K=7.

• International Journal of Computer Science & Network Security
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• v.23 no.8
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• pp.49-62
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• 2023

There has been a rapid increase in the creation and alteration of new malware samples which is a huge financial risk for many organizations. There is a huge demand for improvement in classification and detection mechanisms available today, as some of the old strategies like classification using mac learning algorithms were proved to be useful but cannot perform well in the scalable auto feature extraction scenario. To overcome this there must be a mechanism to automatically analyze malware based on the automatic feature extraction process. For this purpose, the dynamic analysis of real malware executable files has been done to extract useful features like API call sequence and opcode sequence. The use of different hashing techniques has been analyzed to further generate images and convert them into image representable form which will allow us to use more advanced classification approaches to classify huge amounts of images using deep learning approaches. The use of deep learning algorithms like convolutional neural networks enables the classification of malware by converting it into images. These images when fed into the CNN after being converted into the grayscale image will perform comparatively well in case of dynamic changes in malware code as image samples will be changed by few pixels when classified based on a greyscale image. In this work, we used VGG-16 architecture of CNN for experimentation.

• Proceedings of the Korea Information Processing Society Conference
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• 2022.05a
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• pp.432-435
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• 2022

최근 IT 산업의 지속적인 발전으로 사용자들을 위협하는 악성코드, 피싱, 랜섬웨어와 같은 사이버 공격 또한 계속해서 발전하고 더 지능화되고 있으며 변종 악성코드도 기하급수적으로 늘어나고 있다. 지금까지의 시그니처 패턴 기반의 탐지법으로는 이러한 방대한 양의 알려지지 않은 악성코드를 탐지할 수 없다. 따라서 CNN(Convolutional Neural Network)을 활용하여 악성코드를 탐지하는 기법들이 제안되고 있다. 이에 본 논문에서는 CNN 모델 중 낮은 인식 오류율을 지닌 모델을 선정하여 정확도(Accuracy)와 F1-score 평가 지표를 통해 비교하고자 한다. 두 가지의 악성코드 이미지화 방법을 사용하였으며, 2015 년 이후 ILSVRC 에서 우승을 차지한 모델들과, 추가로 2019 년에 발표된 EfficientNet 을 사용하여 악성코드 이미지를 분류하였다. 그 결과 2 바이트를 한 쌍의 좌표로 변환하여 생성한 256 * 256 크기의 악성코드 이미지를 ResNet-152 모델을 이용해 분류하는 것이 우수한 성능을 보임을 실험적으로 확인하였다.