• Journal of Broadcast Engineering
• /
• v.20 no.4
• /
• pp.497-508
• /
• 2015

Current communication networks consist of channels with various throughputs, protocols, and packet loss rates. Moreover, there are also diverse user multimedia consumption devices having different capabilities and screen sizes. Thus, a practical necessity of scalability on video coding have been gradually increasing. Recently, The Scalable High Efficiency Video Coding(SHVC) standard is developed by Joint Collaborative Team on Video Coding(JCT-VC) organized in cooperation with MPEG of ISO/IEC and VCEG of ITU-T. This paper introduces coding tools of SHVC including adopted and unadopted tools discussed in the process of the SHVC standardization. Furthermore, the individual tool and combined tool set are evaluated in terms of coding efficiency relative to a single layer coding structure. This analysis would be useful for developing a fast SHVC encoder as well as researching on a new scalable coding tool.

• Journal of Broadcast Engineering
• /
• v.19 no.1
• /
• pp.14-23
• /
• 2014

This paper proposed controlling methods for SDN(Software Defined Network) based multiple radio access technology as the solutions of following two issues which were mainly occurred by explosive increasing of video traffic. The first one is a requirement for traffic off-loading caused by 3rd-party video service providers from the mobile network operator's viewpoint. The other one is a provision of high-speed video contents transmission services with low price. Furthermore, the performance evaluation was also conducted on the real test-bed which is composed of OpenStack cloud and SDN technology such as OpenFlow and Open vSwitch. A virtual machine running on the OpenStack provide a video service and the terminal which is able to use multiple radio access technology supports two 2.4GHz WLANs(Wireless Local Area Network) and three 5GHz WLANs, concurrently. Finally, we can get 820Mbps of the maximum transmission speed by using that five WLAN links for the single service at the same time.

• Journal of Energy Engineering
• /
• v.29 no.1
• /
• pp.44-51
• /
• 2020

The importance of ESS has been emphasized due to stabilization of power demand due to deterioration of network reliability and expansion of renewable energy sources. ESS (Energy Storage System) stores the remaining power and uses it when necessary to meet the power demand, and build the ESS system mainly in conjunction with solar and wind power. In this paper, we propose a home PV Charging Module using the Master-Slave method which is effective for low insolation. After designing the module, Fast MPPT algorithm is applied to generate the maximum output from the nonlinear output characteristics of the PV modules. The average power value for the input of PV Charging Module was 296.90 W and the output power was 289.60 W, which averaged 97.54%.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.24 no.10A
• /
• pp.1517-1531
• /
• 1999

The Internet is recently evolving into the directions which is capable of incorporating stream-type services such as voice and video services. However, the existing Internet can only support a best-effort delivery model and thus it is difficult to satisfy these requirements as well as to provide the QoS beyond a certain degree. Accordingly, it is imperative to develop QoS based routing algorithm in order to allow the routing by the user's QoS demand and to be applied into wide area networks. In this thesis, we presented new routing algorithms and made performance evaluations. The proposed algorithms allow the routing by the user’s QoS demand level in order to provide the diverse Internet application services based on ATM network environment that is expected to play a role as an infrastructure of high-speed communication network. They also have a feature of shortening the waiting time for address analysis and have a quality-proven characteristics with enhanced network scalability.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.34 no.9A
• /
• pp.712-718
• /
• 2009

This paper proposes the optimal transmission parameter selection method for an energy efficient Wireless Personal Area Network (WPAN) system which is applicable to the Maritime Telematics targeting for various ship models. Since the transmission parameter selection is an important factor for WPAN system to decide its energy efficiency, we propose an energy consumption model for ship area network (SAN) employing IEEE 802.15.3 based TDMA HR-WPAN model and analyzes the effect of transmission parameter selection on the performance of energy consumption. In particular, the main performance decision parameter of the SAN applying HR-WPAN is path loss, since it is very varied according to the material of shipbuilding such as steel (large ship), FRP (medium size ship) and compound wood (small ship). Thus, we analyzed and demonstrated that the proper transmission parameter selection among transmit power, PHY data rate and fragment size for each ship model guarantee the energy efficiency.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.35 no.12B
• /
• pp.1236-1243
• /
• 2010

The perimeter defense system was created and its characteristics were evaluated. It was designed to utilize the fiber sensing device, namely OTDR(Optical Time Domain Reflectometer) which has been used for the maintenance of the optical communication network. An OTDR was constituted by a pulse laser with the nature of 1310nm, +15dBm for the observation of 400 meter optical fence. The high-speed 32-bit processor(S3C2440) has applied to MPU(Main Processor Unit) which helps to improve the performance of OTDR algorithms. Consequently, the maximum error was 0.84 meter on the performance test of the 10km monitoring and the pass criteria of ${\pm}1m$ satisfied in all the sections. The alarm delay time was under 3 sec after detecting the disorder. For the case of secondary trespassing after primary trespassing, the optical switch was installed in OTDR to monitor the secondary trespassing and to measure the multi-point detection. Therefore, this paper shows that the detections of secondary trespassing and multi-point is possible by means of optical switch.

• Journal of the Korea Society of Computer and Information
• /
• v.8 no.2
• /
• pp.97-105
• /
• 2003

This thesis proposes a new type of Input-Output Buffered ATM Switch which employs an arbiter and its performance under different traffic conditions studied. The proposed switch is designed with a view to exploit the architecture and other characteristics of the arbiter The primary aim of the proposed switch is the elimination, or at least, the reduction of HOL blocking phenomenon which occurs in the simple input buffered switch. Several HOL arbitration algorithms have been proposed for this purpose in the literature. The Proposed switch attempts to reduce the HOL blocking as it uses the arbiter and the buffer at the output Port in an effective manner. The arbiter is designed to work with Three Phase Algorithm which is one of the many well known HOL arbitration algorithms . The proposed switch acquires control over priority transmission through the REd signal. As the signals are transmitted to the arbiter, the latter controls the one which is sent by the input buffer. Computer simulation results have been provided to demonstrate the effectiveness of the proposed switch under non-uniform random traffic conditions.

• Journal of KIISE:Computing Practices and Letters
• /
• v.12 no.1
• /
• pp.21-30
• /
• 2006

As the amount of information to be processed by computers has recently been increased, there has been cluster computing systems developed by connecting PCs and workstations using high-speed networks. hs a result, the studies on a cluster-based DBMS have been done with a wide range and it is necessary to develop a cluster manager for monitoring and managing cluster-based DBMSs. But, a cluster manager for efficiently managing cluster-based DBMSs has been studied in a first step. In this paper, we design and implement a high-availability cluster manager for a cluster-based DBMS. It monitors the status of nodes in cluster systems as well as the status of DBMS instances in a node, by using a graphic user interface (GUI). Our cluster manager supports the high-availability for a cluster-based DBMS by perceiving errors and recovering them, based on the monitored information on the status of a server.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.9 no.3
• /
• pp.93-99
• /
• 2009

The Internet Engineering Task Force (lETF)proposed the Mobile IPv6 protocol to provide host mobility in IPv6-based network and to offer a standardized technology. However, Mobile IPv6 (MIPv6) is not applied in actual network because of long handover latency and packet loss problems. Therefore, to compensate these drawbacks, many studies are in progress and FMIPv6 (Fast handover for Mobile IPv6) is one of the studies that has been proposed to supplement the shortcomings of MIPv6. But there are problems occurred in using router tunneling which causes packet loss and out of sequence problems. In this paper, we propose an Advanced Mobile IPv6 (AMIPv6) protocol to minimize the handover latency when Mobile Node frequently moves in each subnet. We compared the performance analysis of AMIPv6 handover latency with MIPv6 handover latency in the same network environment to prove that AMIPv6 is more efficient.

• Journal of the Korean Institute of Intelligent Systems
• /
• v.19 no.1
• /
• pp.145-151
• /
• 2009

Orthogonal Frequency Division Multiplexing (OFDM) has been focused on as 4th generation communication method for realization of Ubiquitous Network in land mobile communications services, and has been a standard technology of Wireless Local Area Network (WLAN) for a High Date Rate communication. And in maritime data communication using high frequency (HF) band, 32-point FFT OFDM system is recommended by International Telecommunication Union (ITU). Maritime communication should be kept on connecting when maritime accident or the maritime disaster happen. Therefore, main device FFT should be operated with low power consumption. In this paper we propose a low power 32-point FFT algorithm using radix-2 and radix-4 for low power operation. The proposed algorithm was designed using VHSIC hardware description language (VHDL), and it was confirmed that the output value of Spartan-3 field-programmable gate array (FPGA) board corresponded to the output value calculated using Matlab. The proposed 32-point FFT algorithm will be useful as a leading technology in a HF maritime data communication.