• Journal of KIISE:Information Networking
• /
• v.29 no.4
• /
• pp.428-436
• /
• 2002

Providing a mobile host with its required QoS is highly influenced by its mobility. The resource ReSerVation Protocol(RSVP) establishes and maintains a reservation state to ensure a given QoS level along the path from the sender to the receiver. However, RSVP is designed for use in fixed networks and thus it is inadequate in the mobile networking environment where a host changes its point of attachment. In this paper, we propose a new resource reservation protocol, RSVP-RA(RSVP by RSVP Agent) for mobile hosts. Our protocol assumes IETF Mobile IP as a mobility support mechanism. The proposed protocol introduce a new protocol entity - RSVP agent - to manage reservations in a mobile host's current visiting network. RSVP Agent is located in a local network and makes resource reservations in neighboring cells that the mobile host is expected to visit in the future. Thus, the proposed Protocol can provide a seamless QoS to the mobile host and significantly improve the scalability problem of RSVP by reducing the end-to-end signalling messages acrossing the backbone networks. The proposed protocols reduce packet delay, bandwidth overhead and the number of RSVP messages to maintain reservation states. We compared the performance of our proposed protocol with other proposed protocols in terms of signalling overhead, packet delay by simulation.

• Journal of Internet Computing and Services
• /
• v.13 no.4
• /
• pp.63-71
• /
• 2012

This paper presents a design and implementation of U-Seum(Ubiquitous Museum) system based on the LBS(Location Based Service) and mobile augmented reality technique. The mobile services under the smart space of the ubiquitous environments have been expanded in the various fields. In this study, we introduce U-Seum which supports tourists in the museum. U-Seum is developed by use of the position tracking technique based on Wi-Fi and mobile augmented reality. The GPS which is widely used in the position tracking has a difficulty to be utilized in the inside of the building because it requires the Line-of-Sight between a sender and a receiver. Therefore, in this paper, we develop a realtime tour-supported service through experience and evaluate the performance of the system in the world famous UNESCO's Hwa-Seong Museum by measuring the distance from the Wi-Fi signal which is suitable to track the position interior of the museum. U-Seum provides various push services such as mobile augmented reality service for explanation of the artifacts of the museum, game services and the statistics information of the tourist when the tourist approach a specific AP. U-Seum is developed in the Haw-Seong Museum by the support of the Swon Haw-Seong Cultural Foundation. With a field test, we prove that the excellence and expandability of the system.

• Journal of KIISE:Information Networking
• /
• v.33 no.1
• /
• pp.76-90
• /
• 2006

Sensor network consists of a large number of sensor nodes that are densely deployed either inside the phenomenon or very close to it. The life time of each node in the sensor network significantly affects the life time of whole sensor network. A node which drained out its battery may incur the partition of whole network in some network topology The life time of each node depends on the battery capacity of each node. Therefore if all sensor nodes in the network live evenly long, the life time of the network will be longer. In this paper, we propose Cluster-Based Power-Efficient Routing (CBPER) Protocol which provides scalable and efficient data delivery to multiple mobile sinks. Previous r(luting protocols, such as Directed Diffusion and TTDD, need to flood many control packets to support multiple mobile sinks and many sources, causing nodes to consume their battery. In CBPER, we use the fact that sensor nodes are stationary and location-aware to construct and maintain the permanent grid structure, which makes nodes live longer by reducing the number of the flooding control packets. We have evaluated CBPER performance with TTDD. Our results show that CBPER is more power-efficient routing protocol than TTDD.

• KIPS Transactions on Software and Data Engineering
• /
• v.9 no.7
• /
• pp.221-228
• /
• 2020

Part-of-Speech (POS) tagged corpus is a collection of electronic text in which each word is annotated with a tag as the corresponding POS and is widely used for various training data for natural language processing. The training data generally assumes that there are no errors, but in reality they include various types of errors, which cause performance degradation of systems trained using the data. To alleviate this problem, we propose a novel method for detecting errors in the existing POS tagged corpus using the classifier of XGBoost and cross-validation as evaluation techniques. We first train a classifier of a POS tagger using the POS-tagged corpus with some errors and then detect errors from the POS-tagged corpus using cross-validation, but the classifier cannot detect errors because there is no training data for detecting POS tagged errors. We thus detect errors by comparing the outputs (probabilities of POS) of the classifier, adjusting hyperparameters. The hyperparameters is estimated by a small scale error-tagged corpus, in which text is sampled from a POS-tagged corpus and which is marked up POS errors by experts. In this paper, we use recall and precision as evaluation metrics which are widely used in information retrieval. We have shown that the proposed method is valid by comparing two distributions of the sample (the error-tagged corpus) and the population (the POS-tagged corpus) because all detected errors cannot be checked. In the near future, we will apply the proposed method to a dependency tree-tagged corpus and a semantic role tagged corpus.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.46 no.5
• /
• pp.139-145
• /
• 2009

Recently P2P (Peer-to-Peer) networks and applications have been expanded to various field. However, because the construction of P2P network did not influence a underlying network topology or property, it may be inefficient. Especially, this inefficiency is more serious in MANET because MANET has narrow bandwidth and energy constraint. When we use a proactive routing protocol in MANET, we can know hop counts between two nodes. And, we can construct a P2P overlay network using this hop count information. However, In case of using hop count only, we can avoid a interference path selection problem and a zig-zag problem. We propose a method of improving P2P contents distribution using virtual positions. We calculate virtual positions from hop counts using the trigonometry. This method solves a interference path selection problem and a zig-zag problem. This method also allows a P2P network to influence underlying network topology. We adopt this method to a network which uses a virtual geographic routing, a proactive routing protocol, or a reactive routing protocol. We show that our proposed methods improve P2P contents distribution performance over MANET through a simulation.

• Review of Culture and Economy
• /
• v.17 no.2
• /
• pp.3-28
• /
• 2014

The characteristics of performing arts differ from those of utilitarian goods in terms of economics. Factors other than price need to be considered to understand the demand for performing arts. Audience surveys as well as econometric demand studies have confirmed that socio-economic factors such as age, income, employment, and education are major determinants of the demand for performing arts. This study focused on the attributes of concerts rather than consumer characteristics to determine the concerts audiences select in terms of transaction cost. Genre, price, internet search trends, and the purpose of performance as well as price are tested as determinants of demand by using the data set for a major concert hall in Seoul. Genre and the specific purpose of concerts influence the demand for concerts. Internet search trends of the performer are used as indicators of popularity and information exposure, which are positively correlated with demand. This result supports the hypothesis that larger audiences would attend concerts that require lower information search costs. To note, price has a positive effect on demand in the higher price range, which means that concerts at higher prices attract larger audiences, whereas normal goods have a negative slope in the demand curve. This result can be explained by the hypothesis that consumers use price as an indicator of the quality expected of a concert. Transaction cost for selecting classical concerts thus forms an inverse-U shape curve against ticket price. These results provide some explanation of why audiences of classical music choose to attend concerts at high ticket prices while offering evidence in favor of the hypothesis that performing arts are selected in a social context.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2016.10a
• /
• pp.256-259
• /
• 2016

The growth of mobile devices in Internet of Things (IoT) leads to a number of intelligent buildings related IoT applications. For instance, home automation controlling system uses client system such web apps on smartphone or web service to access the home server by sending control commands. The home server receives the command, then controls for instance the light system. The gateway based RESTful technology responsible for handling clients' requests attests an internet latency in case a large number of clients' requests submit toward the gateway increases. In this paper, we propose the design tasks of the IoT gateway for handling concurrency events. In the procedure of designing tasks, concurrency is best understood by employing multiple levels of abstraction. The way that is eminently to accomplish concurrency is to build an object-oriented environment with support for messages passing between concurrent objects. We also investigate the performance of event-driven architecture for building IoT gateway using node.js on one side and communication protocol based message-oriented middleware known as XMPP to handle communications of intelligent building control devices connected to the gateway through a centralized hub. The Node.JS is 40% faster than the traditional web server side features thread-based approach. The use of Node.js server-side handles a large number of clients' requests, then therefore, reduces delay in performing predefined actions automatically in intelligent building IoT environment.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.20 no.9
• /
• pp.504-509
• /
• 2019

Recently, both wireless communications technology and the performance of small devices have developed exponentially, while the number of services using various types of Internet of Things (IoT) devices has also massively increased in line with the ongoing technological and environmental changes. Furthermore, ever more devices that were previously used in the offline environment-including small-size sensors and CCTV-are being connected to the Internet due to the huge increase in IoT services. However, many IoT devices are not equipped with security functions, and use vulnerable open source software as it is. In addition, conventional network equipment, such as switches and gateways, operates with vulnerabilities, because users tend not to update the equipment on a regular basis. Recently, the simple vulnerability of IoT devices has been exploited through the distributed denial of service (DDoS) from attackers creating a large number of botnets. This paper proposes a system that is capable of identifying Internet-connected devices quickly, analyzing and managing the vulnerability of such devices using Internet-wide scan technology. In addition, the vulnerability analysis rate of the proposed technology was verified through collected banner information. In the future, the company plans to automate and upgrade the proposed system so that it can be used as a technology to prevent cyber attacks.

• Management & Information Systems Review
• /
• v.37 no.4
• /
• pp.63-74
• /
• 2018

Recently, in the asset management industry, the smart beta strategy, which has an intermediate nature between passive and active strategies, is attracting attention. In this smart beta strategy, value, momentum, low volatility, and quality index are widely used. In this study, we analyzed the quality index which is not clear and complicated to calculate. According to the MSCI methodology, the quality index was calculated using three variables: return on equity, debt to equity, and earnings variability. In addition, we use the index using only return on equity variable, the index using only two variables of return on equity and debt to equity, and the KOSPI index as comparison targets for the quality index. In order to evaluate the performance of the indices used in the analysis, the arithmetic mean return, the coefficient of variation, and the geometric mean return were used. In addition, Fama and French (1993) model, which is widely used in related studies, was used as a pricing model to test whether abnormal returns in each index are occurring. The results of the empirical analysis are as follows. First, in all period analysis, quality index was the best in terms of holding period returns. Second, the quality index performed best in the currency crisis and the global financial crisis. Third, abnormal returns were not found in all indices before the global financial crisis. Fourth, in the period after the global financial crisis, the quality index has the highest abnormal return.

• Journal of Digital Convergence
• /
• v.19 no.8
• /
• pp.89-100
• /
• 2021

The National Cyber Capability Assessment(NCCA) could be used as meaningful information for improving national cyber security policy because it provides information on the elements necessary for strengthening national cyber capabilities and the level of each country. However, there were few studies on improving cyber capabilities using the NCCA result in Korea. Therefore, we analyzed the result of National Cyber Power Index(NCPI) conducted by Belfer Center of Harvard Univ. by applying modified-IPA method to derive cybersecurity policy agendas for Korea. As a result, the need to set agendas on surveillance and offensive cyber capability and improve the effectiveness of policy implementation for intelligence and defense was drawn. Moreover, we suggested need for in-depth study of each policy agenda deduced from preceding research data as a future tasks. And it is expected to increase practical use of NCCA for domestic policy analysis by developing and using our own NCCA model which considered analysis framework proposed in this study.