• The Journal of the Acoustical Society of Korea
• /
• v.35 no.4
• /
• pp.295-302
• /
• 2016

Underwater acoustic communication channel is often defined as a multipath fading channel since the multipath arrivals from various paths interfere with each other and cause frequency dependent constructive or destructive interference in received signals. Therefore signal-to-noise ratio (SNR) of received signal fluctuates as a function of frequency. In addition, sea surface fluctuation induces frequency dependent time variant signal fading due to coherent component variation of surface bounce path. The frequency shift keying (FSK) system is known to be less sensitive and more robust under these interference and fading, and M-ary frequency shift keying (MFSK) system is adopted to increase a data rate. In this study, a bit error rate (BER) of 4 channels 4FSK system are examined in shallow sea multipath channel. Experimental results show that RS code reduces efficiently the BER of 4FSK system since frequency dependent time-varying fading is characterized to give burst errors. The BER of a different data rate or different source-to-receiver range depends on not only the channel coherent bandwidth but also frequency dependent multipath fading.

• Archives of design research
• /
• v.11
• /
• pp.22-29
• /
• 1995

I have to find standpoint of sight moulding of Chi I Sung Hwa(seven stars picture) analysis of graphic systems of a symbol sight native to our nation. And I will comprehend emotion of folkways by simple and graphic lines and colors in mathematical Grid of which ancestor had expressed in gauge moulding consciousness. This papers aim is to make a contribution to lead by on part of communication design. About structural analysis of pictorial graphic side. I) Mathematical thought of the Orient and space constitution are first basically the Orient expressed number notion of mathematics of unlimitedness and notion of zero so called space and empty second can analigize a diagonal expansion method by development of symmetry notion to basic the dual principle of the negative and positive by degrees development expressed space division method by direction notion. 2) About the proportion analysis it based the golden section globularity and in modern layout it takes vision center of position, after appointing the brow of sacred image of Chil Sung Hwa as center point of proportion and applied to the point proportion and so analigized the posibility of established. Rule in union of each elements and rule of forms about picture image. 3) Mathematical structure analysis to search a unified principle at the balanced arrangement and rule of forms it analigized the standard the rule of forms. it analigized the standard the rule of forms to body module of basic movement of protagonist and follower above basic forms of grid that is the basis of design system.

• Journal of the Korean Institute of Telematics and Electronics S
• /
• v.36S no.1
• /
• pp.123-132
• /
• 1999

In this paper, a quadratic sigmoid neural equalizer(QSNE) is proposed to improve the performance of conventional neural equalizer in terms of bit error probability by using a quadratic sigmoid function as the activation function of neural networks. Conventional neural equalizers which have been used to compensate for nonlinear distortions adopt the sigmoid function. In the case of sigmoid neural equalizer, each neuron has one linear decision boundary. So many neurons are required when the neural equalizer has to separate complicated structure. But in case of the proposed QSNF and quadratic sigmoid neural decision feedback equalizer(QSNDFE), each neuron separates decision region with two parallel lines. Therefore, QSNE and QSNDFE have better performance and simpler structure than the conventional neural equalizers in terms of bit error probability. When the proposed QSNDFE is applied to communication systems and digital magnetic recording systems, it is an improvement of approximately 1.5dB~8.3dB in signal to moise ratio(SNR) over the conventional decision feedback equalizer(DEF) and neural decision feedback equalizer(NDFE). As intersymbol interference(ISI) and nonlinear distortions become severer, QSNDFE shows astounding SNR shows astounding SNR performance gain over the conventional equalizers in the same bit error probability.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.36 no.10B
• /
• pp.1150-1158
• /
• 2011

More than 100 Mbps rate is needed in the UBcN for a subscriber to receive broadband traffics with multi-channel like UDTV or 3DTV. Although the optical fiber is recently deployed for the FTTH, the UTP is the most widely used medium and will be used in UBcN age. Network providers may consider the 1000BASE-T or the vectorized VDSL if they adopts the UTP in the place where does not have optical fibers. But UTP should be expanded because 1000BASE-T and vectorized UTP needs 4 and 3 pairs cable, respectively while residential region has not exceeding 2 pair UTP cable. To solve the problem, we propose a 500BASE-T technology using 2 pairs UTP in this paper. The technology introduces a rate adaptation sublayer and a SERDES sublayer above and under the PCS, respectively. The rate adaptation sublayer is compatible for the GMII. Also, if we modify the SERDES sublayer, the technology can easily obtain 250BASE-T with 2 pairs UTP. We implement such functions with FPGA and analog board and verify the function of rate adaptation and symbol vector synchronization, and effective transmission rate by experiments. In particular, we show that link efficiency is increased by enable control in the rate adaptation sublayer.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.25 no.9A
• /
• pp.1290-1298
• /
• 2000

Turbo Code decoder is an iterate decoding technology, which extracts extrinsic information from the bit to be decoded by calculating both forward and backward metrics, and uses the information to the next decoding step Turbo Code shows excellent performance, approaching Shannon Limit at the view of BER, when the size of Interleaver is big and iterate decoding is run enough. But it has the problems which are increased complexity and delay and difficulty of real-time processing due to Interleaver and iterate decoding. In this paper, it is analyzed that MAP(maximum a posteriori) algorithm which is used as one of Turbo Code decoding, and the factor which determines its performance. MAP algorithm proceeds iterate decoding by determining soft decision value through the environment and transition probability between all adjacent bits and received symbols. Therefore, to improve the performance of MAP algorithm, the trust between adjacent received symbols must be ensured. However, MAP algorithm itself, can not do any action for ensuring so the conclusion is that it is needed more algorithm, so to decrease iterate decoding. Consequently, MAP algorithm and Turbo Code performance are analyzed in the nongaussian channel applying Robust equalization technique in order to input more trusted information into MAP algorithm for the received symbols.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.12 no.12
• /
• pp.2153-2158
• /
• 2008

XML is one of standard web languages. XML has a syntax architecture consisted of tags, which are used to descript contents and structures of a XML document. In XML documents, missing of markup tag is one of common factors generating incomplete inputs. Usually, editors will recognize incomplete inputs as syntax errors. And so, when editors find them, they will highlight lines in which syntax errors happened, and execute appropriate error handling routines. But, there are no more parsing actions. In this paper, we propose a method to recognize incomplete input strings and keep parsing phases going. To recognize pars missed grammatically in incomplete inputs and create them newly, we use an expanding parsing table. It includes additional parsing actions for newly generated input symbols. Through the information, incomplete inputs will be completed and parsing steps will be finished successively. Therefore, users can be assured that they make always correct XML documents, even if inputs are incomplete, and can not be nervous about input faults.

• Journal of Broadcast Engineering
• /
• v.20 no.2
• /
• pp.310-339
• /
• 2015

In this paper, the possibility of a terrestrial fixed 4K UHD (Ultra High Definition) and mobile HD (High Definition) convergence broadcasting service through a single channel employing the FEF (Future Extension Frame) multiplexing technique in DVB (Digital Video Broadcasting)-T2 (Second Generation Terrestrial) systems is examined. The performance of such a service is also investigated. FEF multiplexing technology can be used to adjust the FFT (fast Fourier transform) and CP (cyclic prefix) size for each layer, whereas M-PLP (Multiple-Physical Layer Pipe) multiplexing technology in DVB-T2 systems cannot. The convergence broadcasting service scenario, which can provide fixed 4K UHD and mobile HD broadcasting through a single terrestrial channel, is described, and transmission requirements of the SHVC (Scalable High Efficiency Video Coding) technique are predicted. A convergence broadcasting transmission system structure is described by employing FEF and transmission technologies in DVB-T2 systems. Optimized transmission parameters are drawn to transmit 4K UHD and HD convergence broadcasting by employing a convergence broadcasting transmission structure, and the reception performance of the optimized transmission parameters under AWGN (additive white Gaussian noise), static Brazil-D, and time-varying TU (Typical Urban)-6 channels is examined using computer simulations to find the TOV (threshold of visibility). From the results, for the 6 and 8 MHz bandwidths, reliable reception of both fixed 4K UHD and mobile HD layer data can be achieved under a static fixed and very fast fading multipath channel.

• Journal of the Korean Institute of Traditional Landscape Architecture
• /
• v.29 no.2
• /
• pp.118-129
• /
• 2011

This study is about the governor general's official residence and its garden in Yongsan that were constructed during the Japanese occupational time. The garden design drawing was also made while planning such Neo-Baroque style building, and it contains particular information of the garden unlike the other existing landscape drawings. The content of garden translated and landscape historical value drawn out by analysis of garden drawings, press articles and literatures are as follows; First, such governor general's official residence garden in Yongsan is likely to be the Korean first western style landscape form. For, from the point that it was completely constructed together with such official residential building in 1909, its construction time should be before that of the garden of Seokjojeon, Deoksu Palace, which was constructed in 1911. Second, it shows the garden style and garden planting factors introduced together with the modern architecture then. Such garden planting factors are placed from the center axis of the garden that is connected to the center of the building and monument as well. Such style and factors cover and show the flower bed appearing in Baroque style gardens, the monument that forms Vista playing the center of audience's vision, water space that is placed symmetrically against the axis, planting pattern that emphasizes the plants' space, flower bed shape and axis, and what kinds of plants were introduced then. Third, it shows the using pattern of western style gardens. Western style garden parties used to take in place in this garden while official dinner and reception were held in the evening in the official residence. Fourth, it shows the historical value as a modern landscape drawing, which is the Korean first landscape drawing that shows the plants' names and planting techniques marking the current height and planned height for change of topography and water system as a water landscape factor. That is, this drawing has the value that it was upgraded from the other existing ones that expressed only simple plants' symbols or flower bed shapes. I, therefore, hope that the studies on the modern landscape would be getting wider by excavation of new historical records in the future.