• Journal of Broadcast Engineering
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• v.25 no.1
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• pp.36-47
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• 2020

The improved belief-propagation-based algorithms, such as normalized min-sum algorithm (NMSA) or offset min-sum algorithm (OMSA), are widely used to decode LDPC(Low-Density Parity-Check) codes because they are less computationally complex and work well even at low SNR(Signal-to-Noise Ratio). However, these algorithms work well only when an appropriate normalization factor or offset value is used. A new method that uses a CMD(Check Node Message Distribution) chart and least-square method, which has been recently proposed, has advantages on computational complexity over other approaches to get optimal coefficients. Furthermore, this method can be used to derive coefficients for each iteration. In this paper, we apply this method and propose an algorithm to derive a combination of normalization factor and offset value for a combined normalized and offset min-sum algorithm to further improve the decoding of LDPC codes. Simulations on the next-generation broadcasting standards, ATSC 3.0 LDPC codes, prove that a combined normalized and offset min-sum algorithm which takes the proposed coefficients as correction coefficients shows the best BER performance among other decoding algorithms.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.1A
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• pp.64-72
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• 2012

We consider multiuser multiple antenna two-way relaying systems in which all users exchange their data with their counterparts with the help of a relay. The systems complete all data exchanges in two time phases called multiple access phase and broadcasting phase for spectral efficiency and therby require an effective scheme reducing self-interference (SI) and multiuser interference (MUI). Different from the conventional scheme suppressing both SI and MUI at the relay, the proposed scheme adopts SI cancelation (SIC) at the users and renders the relay to suppress the MUI mainly considering the SIC output. We analyze the symbol error rate (SER) and the achievable diversity order of the proposed scheme when the multiple access phase is dominant in the performance and obtain simulation results on the SER and the sum rate under various conditions. The results show that the proposed scheme improves the symbol error rate and the sum rate remarkably at the cost of complexity increase.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.11C
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• pp.1049-1058
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• 2009

After the efficiency of H.264 video compression has been announced, it replaced MPEG-2 standard in several applications. So transcoding methods of MPEG-2 to H.264 have been studying because there are variety devices and contents followed by MPEG-2. Although H.264 supported various service such as IPTV, DMB, digital broadcasting etc, but users using MPEG-2 devices cannot accessible to them. This paper propose H.264 to MPEG-2 transcoding for users of MPEG-2 devices without displacement H.264. The proposed method predicted a motion vector for MPEG-2 encoder after it extracted from motion vectors of variable blocks in H.264 to improve processing time. Also it predicted a optimal motion vector using modified boundary matching algorithm after grasped a special character for boundary and background of object. The experimental results from proposed method show a considerable reduction in processing time, as much as 65% averagely, with a small objective quality reduction in PSNR.

• Journal of the Korea Society of Computer and Information
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• v.13 no.4
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• pp.133-140
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• 2008

The cable TV network has delivered downward broadcasting signals from distribution centers to subscribers. Since the traditional coaxial cable has been upgraded by the Hybrid Fiber Coaxial(HFC) cable, the upward channels has expanded broadband services such as Internet. This upward channel is vulnerable to ingress noises. When the noises from the children nodes accumulated in an amplifier exceeds a certain level, that node has to be cut off to prevent the noise propagation. The node selection problem(NSP) is defined to select nodes so that the noise in each node does not exceed the given threshold value and the sum of Profits of selected nodes can be maximized. The NSP has shown to be NP-hard. In this paper, we have proposed heuristics to find the near-optimal solution for NSP. The experimental results show that interval partitioning is better than greedy approach. Our heuristics can be used by the HFC network management system to provide privileged services to the premium subscribers on HFC networks.

• Journal of the Korean Dietetic Association
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• v.9 no.2
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• pp.138-148
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• 2003

The purpose of this study was to analyze information about food and nutrition topics presented throughout the television broadcast media, thereby suggest the optimal communication method to give right information to the general public. To perform this study, total sixteen monitoring people were recruited and trained through monitoring practice before and during the study . Five domestic TV channels were selected to be monitored, for six months. For the best efficiency, all the monitoring people were divided into 8 teams based on the regional consideration. The statistical analysis of data was completed using SAS program. The main results of this study are as follows. First, the total reporting cases of information about foods and nutrition were 237 , among which about 30% was classified as appropriate and 70% as inappropriate based on the trained monitors' evaluation. Second, the analysis of contents about incorrect informations showed that the insufficient descriptions of terminology and contents were the highest. And insufficient scientific evidences, incorrect contents excessively entertainment-oriented, no provision of alternatives , improper selection of expert advisors were followed. These results suggest that systematical monitoring should be continued to reduce the frequency of incorrect communication thereby give the right information in food and nutrition area to the general public. And there should be a closely cooperated system to provide the professional information to broadcasting production team by establishing the strategic program. In order to do that, most importantly the advisory team should be organized to professionally connect mass media to corresponding specialists. In addition, more educational programs about food and nutrition should be developed to provide right information to the general public.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.10
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• pp.1075-1085
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• 2008

Recently, it is studied actively that DVB-S2 for mobility standard(DVB-S2M) is combined with DVB-H, DVB-T and conventional DVB-S2 standard for continuous satellite broadcasting and internet service. Especially, overcoming deep fading by tunnel is main subject. For overcoming deep fading, DVB-S2M proposed cross layer system is consist of upper layer and physical layer. Thus, this paper proposed optimal upper layer coding system fixing the physical layer coding under the simulation results by coding methods, train speed, data rate, interleaver size and IP packet size.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.6C
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• pp.483-491
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• 2012

In vehicle-to-vehicle (V2V) communications, each vehicle should periodically disseminate a beacon message including the kinematics information, such as position, speed, steering, etc., so that a neighbor vehicle can better perceive and predict the movement of the vehicle. However, a simple broadcasting of such messages may lead to a low reception probability as well as an excessive delay. In this paper, we attempt to analyze the impact of the following key parameters of the beacon dissemination on the performance of vehicular networks: beacon period, carrier-sensing range, and contention window (CW) size. We first derive a beacon period which is inversely proportional to the vehicle speed. Next, we mathematically formulate the maximum beacon load to demonstrate the necessity of the transmit power control. We finally present an approximate closed-form solution of the optimal CW size that leads to the maximum throughput of beacon messages in vehicular networks.

• International journal of advanced smart convergence
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• v.7 no.1
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• pp.42-47
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• 2018

Recently, as the demand for limited resources continues to rise and problems of resource depletion rise worldwide, the importance of renewable energy is gradually increasing. In order to solve these problems, various methods such as energy conservation and alternative energy development have been suggested, and biogas, which can utilize the gas produced from biomass as fuel, is also receiving attention as the next generation of innovative renewable energy. New and renewable energy using biogas is an energy production method that is expected to be possible in large scale because it can supply energy with high efficiency in compliance with energy supply method of recycling conventional resources. In order to more efficiently produce and manage these biogas, a biogas plant has emerged. In recent years, a large number of biogas plants have been installed and operated in various locations. Organic wastes corresponding to biogas production resources in a biogas plant exist in a wide variety of types, and each of the incoming raw materials is processed in different processes. Because such a process is required, the case where the biogas plant process is inefficiently operated is continuously occurring, and the economic cost consumed for the operation of the biogas production relative to the generated biogas production is further increased. In order to solve such problems, various attempts such as process analysis and feedback based on the feedstock have been continued but it is a passive method and very limited to operate a medium/large scale biogas plant. In this paper, we propose "CNN-based production yield prediction algorithm for increasing process efficiency of biogas plant" for efficient operation of biogas plant process. Based on CNN-based production yield forecasting, which is one of the deep-leaning technologies, it enables mechanical analysis of the process operation process and provides a solution for optimal process operation due to process-related accumulated data analyzed by the automated process.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.2
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• pp.279-285
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• 2011

The next generation wireless communication systems are required high BER performance better than present performance. Double binary Turbo code have error floor at high SNR, so it cannot be used in next generation wireless communication system. Therefore, many methods are proposed for overcome error floor at DVB-RCS NG(next generation). In this paper, we analysis structure of third-dimension Turbo code(3D-turbo code). 3D-Turbo code overcomes error flow by additive post-encoder in conventional DVB-RCS Turbo code. Performance of 3D-Turbo code is changed by post-encoder form, interleaving method, value of ${\lambda}$. So we are simulated by those parameter and proposed optimal form. By a result, performance of 3D-Turbo is better than conventional DVB-RCS Turbo code and it overcome error floor of conventional DVB-RCS Turbo code.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.5C
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• pp.454-463
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• 2010

After the efficiency of H.264 video compression has been announced, it replaced MPEG-2 standard in several applications. So transcoding methods of MPEG-2 to H.264 have been studying because there are variety devices and contents followed by MPEG-2. Although H.264 supported various service such as IPTV, DMB, digital broadcasting etc, but users using MPEG-2 devices cannot accessible to them. This paper propose H.264 to MPEG-2 transcoding for users of MPEG-2 devices without displacement H.264. The proposed method predicted a motion vector for MPEG-2 encoder after it extracted from motion vectors of variable blocks in H.264 to improve processing time. Also it predicted a optimal motion vector using modified boundary matching algorithm after grasped a special character for boundary and background of object. The experimental results from proposed method show a considerable reduction in processing time, as much as 68% averagely, with a small objective quality reduction in PSNR.