• Journal of the Institute of Electronics Engineers of Korea TC
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• v.47 no.8
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• pp.99-107
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• 2010

In a single frequency network (SFN) for Advanced Television Systems Committee (ATSC) terrestrial digital television (DTV) system, the interferences induced by the multiple transmitters and/or repeaters using the same frequency are inevitable. Since the presence of interferences results in performance degradation of the SFN, it is crucial to manipulate the interferences by adjusting the transmit power and timing of each transmitter and repeater. In the ATSC terrestrial DTV system, in order to facilitate the interference manipulation process, a transmitter identification (TxID) signal which is uniquely embedded in the signal to be transmitted from each transmitter and repeater is recommended. Even though the injection level of the TxID signal is much lower than the DTV signal, the TxID signal injection infects the DTV signal. Hence, the effect of the TxID signal on the DTV signal must be investigated before deployment. In this paper, the effect of the TxID signal on the performance of legacy DTV receivers under additive white Gaussian noise and multipath channel environments is investigated not only with computer simulation but also with laboratory and field tests. The test results show that the average threshold of visibility degradation of the legacy DTV receivers due to the TxID signal injection is less than 0.2 dB at the TxID injection level of -30 dB.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.4 no.3 s.8
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• pp.61-72
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• 2005

This paper is designed to report the results of response manual development in relation to the freeway Incident Management System(FIMS) development as part of Intelligent Transportation Systems Research and Development program. The central core of the FIMS is an integration of the component parts and the modular, but integrated system for freeway management. The whole approach has been component-orientated, with a secondary emphasis being placed on the traffic characteristics at the sites. The first task taken during the process was the selection of the required actions for each step within the Incident Management System. After through review and analysis of existing incident response procedures and manuals, the incident response manual led to the utilization of different technologies and actions in relation to the specific needs and character of the incidents. FIMS also provides Integrated Incident Management according to the verified incident information provided by the each components The deployment of containment and mitigation strategies for incidents will be automatic or manual depending on the configuration of the system. It is anticipated that, over a period of time, operators will be able to response the incident using integrated and organized Procedures and action items.

• The KIPS Transactions:PartC
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• v.15C no.5
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• pp.351-358
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• 2008

Recently, as network flooding attacks such as DoS/DDoS and Internet Worm have posed devastating threats to network services, rapid detection and proper response mechanisms are the major concern for secure and reliable network services. However, most of the current Intrusion Detection Systems(IDSs) focus on detail analysis of packet data, which results in late detection and a high system burden to cope with high-speed network environment. In this paper we propose a lightweight and fast detection mechanism for traffic flooding attacks. Firstly, we use SNMP MIB statistical data gathered from SNMP agents, instead of raw packet data from network links. Secondly, we use a machine learning approach based on a Support Vector Machine(SVM) for attack classification. Using MIB and SVM, we achieved fast detection with high accuracy, the minimization of the system burden, and extendibility for system deployment. The proposed mechanism is constructed in a hierarchical structure, which first distinguishes attack traffic from normal traffic and then determines the type of attacks in detail. Using MIB data sets collected from real experiments involving a DDoS attack, we validate the possibility of our approaches. It is shown that network attacks are detected with high efficiency, and classified with low false alarms.

• The KIPS Transactions:PartC
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• v.14C no.2
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• pp.147-154
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• 2007

Network topology in ad hoc networks keeps changing because of node mobility and no limitation in number of nodes. Therefore, the scalability of routing protocol is of great importance, However, table driven protocols such as DSDV have been known to be suitable for relatively small number of nodes and low node mobility, Various protocols like FSR, OLSR, and PCDV have been proposed to resolve scalability problem but vet remain to be proven for their comparative superiority for scalability, In this paper, we compare and amine them by employing various network deployment scenarios as follows: network dimension increase's while keeping node density constant node density increases while keeping network dimension fixed, and the number of sessions increase with the network dimension and the number of nodes fixed. the DSDV protocol showed a low scalability despite that it imposes a low overhead because its convergence speed against topology change is slow, The FSR's performance decreased according to the increase of overhead corresponding to increasing number of nodes, The OLSR with the shortest convergence time among them shows a good scalability, but turned out to be less scalable than the PCDV that uses a clustering because of its relatively high overhead.

• KIPS Transactions on Computer and Communication Systems
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• v.2 no.9
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• pp.381-392
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• 2013

During the last decade, the multitude of advances attained in terminal computers, along with the introduction of mobile hand-held devices, and the deployment of high speed networks have led to a recent surge of interest in Quality of Service (QoS) for video applications. The main difficulty is that mobile devices experience disparate channel conditions, which results in different rates and patterns of packet loss. One way of making more efficient use of network resources in video services over wireless channels with heterogeneous characteristics to heterogeneous types of mobile device is to use a scalable video coding (SVC). An SVC divides a video stream into a base layer and a single or multiple enhancement layers. We have to ensure that the base layer of the video stream is successfully received and decoded by the subscribers, because it provides the basis for the subsequent decoding of the enhancement layer(s). At the same time, a system should be designed so that the enhancement layer(s) can be successfully decoded by as many users as possible, so that the average QoS is as high as possible. To accommodate these characteristics, we propose an efficient transmission scheme which incorporates SVC-aware dual-channel repetition to improve the perceived quality of services. We repeat the base-layer data over two channels, with different characteristics, to exploit transmission diversity. On the other hand, those channels are utilized to increase the data rate of enhancement layer data. This arrangement reduces service disruption under poor channel conditions by protecting the data that is more important to video decoding. Simulations show that our scheme safeguards the important packets and improves perceived video quality at a mobile device.

• Journal of Korean Society of Transportation
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• v.19 no.5
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• pp.21-33
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• 2001

Intelligent Transport Systems (ITS) was first introduced in Korea early 1990's, and Korean government has put a lot of efforts for flourishing it in the entire nation. Regardless of these efforts, private participation is not active enough to accelerate ITS implementation in Korea. Expert group made every endeavor to analyze the current situation, and found out some phenomena. It may be summarized as two folds. Firstly, private sector has a lack of confidence on the future ITS market. Budget in the strategic plan is the only publication and guide that private sector can refer to, and it merely indicates deployment costs. Secondly, direction and procedure of R&D are not well defined. It implies that private sector takes too much risk when they invest for R&D. This research, therefore, focuses on the first issues. Concretely, the goal of the project was to establish and analyze the model for estimation the future ITS market side. Author reviewed both quantitative and qualitative models, and concluded that diffusion model in qualitative model was suitable for ITS market estimation. According to model calibration. it is estimated that 14 trillion Won was the market size in 2020 under normal condition. Impact of this result may seduce Information Technology(IT) related private companies into ITS market. Although this research couldn't cover various topics, it nay dedicate in boosting ITS in Korea. Also, it will be a good starting point for further study for the advancement of ITS.

• Journal of KIISE:Computing Practices and Letters
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• v.16 no.2
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• pp.163-176
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• 2010

The representative method to efficiently manage the organization's data is to avoid data duplication through the promotion of sharing and reusing existing data. The systematic structuring of existing data and efficient searching should be supported in order to promote the sharing and reusing of data. Without regard for these points, the data for the system development would be duplicated, which would deteriorate the quality of the data. Data taxonomy provides some methods that can enable the needed data elements to be searched quickly with a systematic order of managing data. This paper proposes that the Origin data taxonomy method can best maximize data sharing, reusing, and consolidation, and it can be used for Meta Data Registry (MDR) and Semantic Web efficiently. The Origin data taxonomy method constructs the data taxonomy structure built upon the intrinsic nature of data, so it can classify the data with independence from business classification. Also, it shows a deployment method for data elements used in various areas according to the Origin data taxonomy structure with a data taxonomic procedure that supports the proposed taxonomy. Based on this case study, the proposed data taxonomy and taxonomic procedure can be applied to real world data efficiently.

• Journal of KIISE:Computing Practices and Letters
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• v.16 no.4
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• pp.421-426
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• 2010

Due to the ease of deployment and the extended coverage, wireless mesh networks (WMNs) are gaining popularity and research focus. For example, the routing protocols that enhance the throughput on the WMNs and the link quality measurement schemes are among the popular research topics. However, most of these works assume that the locations of the mesh routers are predetermined. Since the operators in an Indoor mesh network can determine the locations of the mesh routers by themselves, it is essential to the WMN performance for the mesh routers to be initially placed by considering the performance issues. In this paper, we propose a mesh router placement scheme based on genetic algorithms by considering the characteristics of WMNs such as interference and topology. There have been many related works that solve similar problems such as base station placement in cellular networks and gateway node selection in WMNs. However, none of them actually considers the interference to the mesh clients from non-associated mesh routers in determining the locations of the mesh routers. By simulations, we show that the proposed scheme improves the performance by 30-40% compared to the random selection scheme.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.47 no.11
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• pp.43-53
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• 2010

Wide deployment of high resolution video services leads to active studies on high speed video processing. Especially, prevalent employment of multi-core systems accelerates researches on high resolution video processing based on parallelization of multimedia software. In this paper, we propose a novel parallel H.264/AVC decoding scheme on a multi-core platform. Parallel H.264/AVC decoding is challenging not only because parallelization may incur significant synchronization overhead but also because software may have complicated dependencies. To overcome such issues, we propose a novel approach called Multi-Threaded Parallelization(MTP). In MTP, to reduce synchronization overhead, a separate thread is allocated to each stage in the pipeline. In addition, an efficient memory reuse technique is used to reduce the memory requirement. To verify the effectiveness of the proposed approach, we parallelized FFmpeg H.264/AVC decoder with the proposed technique using OpenMP, and carried out experiments on an Intel Quad-Core platform. The proposed design performs better than FFmpeg H.264/AVC decoder before the parallelization by 53%. We also reduced the amount of memory usage by 65% and 81% for a high-definition(HD) and a full high-definition(FHD) video, respectively compared with that of popular existing method called 2Dwave.

• Journal of Energy Engineering
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• v.25 no.4
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• pp.251-258
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• 2016

This article reports current status of micro fuel cell-combined heat and power (${\mu}FC$-CHP) systems which utilize both power and heat generated by fuel cells. There are several options for constructing CHP systems and among them, fuel cells are the most useful and their total energy efficiency combining heat and power can reach up to about 90%. Fuel cells are classified as five types based on the electrolyte, but the most suitable fuel cell types for the ${\mu}FC$-CHP system are proton exchange membrane fuel cells (PEMFCs) and solid oxide fuel cells (SOFCs). ${\mu}FC$-CHP systems have several advantages such as decrease of the transmission-distribution loss, reduced costs of electricity due to distributed power generation, and environmental-friendliness owing to zero emission. The main drawback of the ${\mu}FC$-CHP systems is the high initial investment, however, it keeps decreasing as the technology development reduces production costs. Currently, Japan is the most leading country of the ${\mu}FC$-CHP market, however, Korea tries to expand the market by planning the deployment of 1 million units of ${\mu}FC$-CHP systems and governmental subsidiary supporting of half of the install price. In this report, integration technologies for connecting FC and CHP, and technology trends of leading countries are presented as well.