• Journal of Satellite, Information and Communications
• /
• v.2 no.2
• /
• pp.59-63
• /
• 2007

In this paper, we propose an advanced Ka-band satellite HD broadcasting system using scalable video coding technology. As already known, it is not so easy to achieve reasonable link availability on Ka-band because of the rain-attenuation effect, and in case of HD broadcasting service it's more difficult. To overcome that problem, we propose an hierarchical broadcasting system based on H.264 SVC technology. In this paper, we suggest a few types of system scenario to realize the concept. Those scenarios are including DVB-S and DVB-S2 and spatially scalable video stream is the source stream in all cases.

• Journal of Navigation and Port Research
• /
• v.43 no.6
• /
• pp.353-360
• /
• 2019

Technology-driven development of a new system makes it difficult for users and stakeholders to identify or intervene in the development process, resulting in systems with unnecessary functions and poor quality services. Applying the software architecture design process to the initial design of the navigation system platform of autonomous ships enables the development of a system that reflects the required functions and service quality of the stakeholders. The design, which includes all of the subsystems that make up an autonomous ship platform, is close to an enterprise architecture. Thus, we strived to design a navigation system platform suitable for the design range of the software architecture. This study analyzed the definition of functional requirements, and quality attributes by applying the software architecture design procedure. This study was conducted to identify the characteristics of the navigation system and platform needs, and the stakeholders were identified. To derive the functional requirements and constraints of the platform, a quality attributes workshop was held engaging stakeholders, and the results of the analysis of functional requirements and quality attributes were listed. Based on the results of this study, the architect can establish the evidence and technical solutions that are integral for the architecture development, and will facilitate the creation of quality attribute scenarios.

• Journal of Communications and Networks
• /
• v.7 no.4
• /
• pp.509-524
• /
• 2005

Due to the strict requirements of emerging applications, per-flow admission control is gaining increasing importance. One way to implement per-flow admission control is using an on­path resource reservation protocol, where the admission decision is made hop-by-hop after a new flow request arrives at the network boundary. The next-steps in signaling (NSIS) working group of the Internet engineering task force (IETF) is standardising such an on-path signaling protocol. One of the reservation methods considered by NSIS is reduced-state mode, which, suiting the differentiated service (DiffServ) concept, only allows per-class states in interior nodes of a domain. Although there are clear benefits of not dealing with per-flow states in interior nodes-like scalability and low complexity-, without per-flow states the handling of re-routed flows, e.g., after a failure, is a demanding and highly non-trivial task. To be applied in carrier-grade networks, the protocol needs to be resilient in this situation. In this article, we will explain the consequences of a route failover to resource reservation protocols: Severe congestion and incorrect admission decisions due to outdated reservation states. We will set requirements that handling solutions need to fulfill, and we propose extensions to reduced-state protocols accordingly. We show with a set of simulated scenarios that with the given solutions reduced-state protocols can handle re-routed flows practically as fast and robust as stateful protocols.

• Structural Monitoring and Maintenance
• /
• v.4 no.1
• /
• pp.1-15
• /
• 2017

Installation of sensors networks for continuous in-service monitoring of structures and their efficiency conditions is a current research trend of paramount interest. On-line monitoring systems could be strategically useful for road infrastructures, which are expected to perform efficiently and be self-diagnostic, also in emergency scenarios. This work researches damage detection in composite concrete-steel structures that are typical for highway overpasses and bridges. The techniques herein proposed assume that typical damage in the deck occurs in form of delamination and cracking, and that it affects the peak power spectral density of dynamic curvature. The investigation is performed by combining results of measurements collected by long-gauge fiber optic strain sensors installed on monitored structure and a statistic approach. A finite element model has been also prepared and validated for deepening peculiar aspects of the investigation and the availability of the method. The proposed method for real time applications is able to detect a documented unusual behavior (e.g., damage or deterioration) through long-gauge fiber optic strain sensors measurements and a probabilistic study of the dynamic curvature power spectral density.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.18 no.2
• /
• pp.55-62
• /
• 2018

VANET is a rapidly emerging service area with strict requirements of a few milliseconds' latency. Because current systems don't guarantee ultra-low latency, it has been proposed a latency-guaranteed Autonomous ATDMA(ATDMA) in which autonomous joining/leaving is allowed without coordinator's scheduling. In this study, we extended ATDMA to operate in non-perfect decoding environments with existing hidden nodes, channel fading and node density variation, and named it ATDMA revision(ATDMA-R). We also evaluated the performance of ATDMA and ATDMA-R, and showed the robustness of ATDMA-R through various realistic simulation scenarios.

• Journal of Korea Society of Digital Industry and Information Management
• /
• v.10 no.3
• /
• pp.71-85
• /
• 2014

This study proposes the future strategy of semiconductor companies corresponding to the growth of cloud computing. Cloud computing is the delivery of IT resources such as hardware and software as a service rather than a product, and it is expected to significantly change the IT market. By employing the scenario planning method, this study develops a total of eight scenario cases, and presents the three possible scenarios including the best market, the worst market, and the neutral market scenario. This study suggests the future strategy of semiconductor companies based on the best market scenario (increasing firms' IT expenditure, increasing the complexity and performance of devices, the frequent replacement of devices). The suggested future strategy of semiconductor includes that the semiconductor companies need to strengthen their price competitiveness, secure the next generation technologies, and develop the better capability for market prediction with the growth of cloud computing. This study will help semiconductor companies set up the strategy direction of technology development, and understand the connections between cloud computing and the memory semiconductor industry. This study has practical implications for semiconductor industry to prepare for the future of cloud computing.

• International journal of advanced smart convergence
• /
• v.1 no.1
• /
• pp.19-26
• /
• 2012

The deployment of mobile femtocellular networks can enhance the service quality for the users inside the vehicles. The deployment of mobile femtocells generates a lot of handover calls. Also, numbers of group handover scenarios are found in mobile femtocellular network deployment. The ability to seamlessly switch between the femtocells and the macrocell networks is a key concern for femtocell network deployment. However, until now there is no effective and complete handover scheme for the mobile femtocell network deployment. Also handover between the backhaul networks is a major concern for the mobile femtocellular network deployment. In this paper, we propose handover control between the access networks for the individual handover cases. Call flows for the handover between the backhaul networks of the macrocell-to-macrocell case are proposed in this paper. We also propose the link switching for the FSO based backhaul networks. The proposed resource allocation scheme ensures the negligible handover call dropping probability as well as higher bandwidth utilization.

• Journal of the Korean Society for information Management
• /
• v.23 no.4 s.62
• /
• pp.111-128
• /
• 2006

The purpose of this study is to measure economic value of full-text information services in order to determine whether it is worth for libraries to invest a large amount of money in constructing database to begin with. The study applied an contingent valuation method to measure its economic value. The imaginary scenarios are designed for estimation the value of Non-market-goods, estimation in advance and experts investigation are needed for rising the confidence level, double-bounded dichotomous choice is chosen in question method. The use value, which one user is willing to pay for domestic monograph full-text information services, was 836 won per one monograph. And, the annual non-use value was 236 won. The total annual economic value of all the students was 831 billion won.

• Korean System Dynamics Review
• /
• v.3 no.1
• /
• pp.5-42
• /
• 2002

The main purpose of this paper is analyzing long-term growth possibility of a telecommunication Company (Telco) H. First of all, to achieve this purpose, the precise understanding about causal relations among growth and decay factors of Telco H is required. Based upon the causal analysis, a basic computer simulation model is developed. Finally, several predictive examinations about growth possibility and pattern of the Telco H are conducted using three scenarios. From simulation results, the most important policy leverages are capabilities of market share sustenance, improvement of service quality and squeezing current network facility to elevate profitability and efficiency. Recently, telecommunication industry has become more and more competitive due to introduction of Internet and deregulation. Internet has brought about global competition as well as confusion between telecommunication and broadcasting industries. At the almost same time, deregulation is a universal tendency and a catalyst of unlimited competition. Telco H has been a dominant company in Korea for last century. However, the dominant position of Telco H has been threatened by the change of competition environment. The competitive environment has many elements and keeps changing dynamically. Therefore, System Dynamics simulation methodology is adopted to examine the problem.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.10 no.7
• /
• pp.3319-3338
• /
• 2016

Cloud storage is becoming more and more popular because of its elasticity and pay-as-you-go storage service manner. In some cloud storage scenarios, the data that are stored in the cloud may be shared by a group of users. To verify the integrity of cloud data in this kind of applications, many auditing schemes for shared cloud data have been proposed. However, all of these schemes do not consider the access authorization problem for users, which makes the revoked users still able to access the shared cloud data belonging to the group. In order to deal with this problem, we propose a novel public auditing scheme for shared cloud data in this paper. Different from previous work, in our scheme, the user in a group cannot any longer access the shared cloud data belonging to this group once this user is revoked. In addition, we propose a new random masking technique to make our scheme preserve both data privacy and identity privacy. Furthermore, our scheme supports to enroll a new user in a group and revoke an old user from a group. We analyze the security of the proposed scheme and justify its performance by concrete implementations.