• Journal of KIISE:Information Networking
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• v.33 no.4
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• pp.289-298
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• 2006

Algorithms for application-level multicast often use trees to deliver data from the source to the multiple receivers. With the tree structure, the throughput experienced by the descendant nodes will be determined by the performance of the slowest ancestor node. Furthermore, the failure of an ancestor node results in the suspension of the session of all the descendant nodes. This paper focuses on the transmission of data using multiple virtual forwarders, and suggests a scheme to overcome the drawbacks of the plain tree-based application layer multicast schemes. The proposed scheme elects multiple forwarders other than the parent node of the delivery tree. A receiver receives data from the multiple forwarders as well as the parent node and it can increase the amount of receiving data per time unit. The multiple forwarder helps a receiver to reduce the impact of the failure of an ancestor node. The proposed scheme suggests the forwarder selection algorithm to avoid the receipt of duplicate packets. We implemented the proposed scheme using MACEDON which provides a development environment for application layer multicast. We compared the proposed scheme with Bullet by applying the implementation in PlanetLab which is a global overlay network. The evaluation results show that the proposed scheme enhanced the throughput by 20 % and reduced the control overhead over 90 % compared with Bullet.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.12B
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• pp.1450-1458
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• 2011

The HPcN (Hybrid & high Performance Convergence Network) in research networks means environment which can provide both computing resource such as supercomputer, cluster and network resource to application researchers in the field of medical, bio, aerospace and e-science. The most representative research network in Korea, KREONET has been developing following technologies through the HERO (Hybrid Networking project for research oriented infrastructure) from 200S. First, we have constructed and deployed a control plane technology which can provide a connection oriented network dynamically. Second, the integrated resource management system technology has been developing for reservation and allocation of both computing and network resources, whenever users want to utilize them. In this paper, a testbed network is presented, which is possible to reserve and allocate network resource using the integrated resource management system. We reserve network resource through GNSI (Grid Network Service Interface) messages between GRS (Global Resource Scheduler) and NRM (Network Resource Manager) and allocate network resource through GUNI (Grid User Network Interface) messages between the NRM (network resource manager) and routers, based on reservation information provided from a user on the web portal. It is confirmed that GUNI interface messages are delivered from the NRM to each router at the starting of reservation time and traffic is transmitted through LSP allocated by the NRM.

• Journal of Digital Convergence
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• v.14 no.1
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• pp.151-161
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• 2016

As part of a policy to address climate change and pollution problem, the government introduced a green credit card scheme in order to motivate pro-environmental behaviors in July 2011. It is important to present the specific ways to facilitate pro-environmental behaviors using the consumer behavior pattern data. This study was a result of data from total fifty seven thousands customer purchasing history data of green credit card to be created for the 3 months from January to March 2015. As the analysis process is put in to operation the analysis of the purchasing customer's profile firstly, and the second come into association analysis to consider the buying associations for green products purchasing networks, the third estimate the useful parameters to affect the customer's pro-environmental behavior and customer characteristics. It shows that royal customers are from 30 to 40 years old and their incomes are from 30 million won to 40 million won. Especially, they live in Daegu, Gyeonggi, and Seoul.

• Journal of the Korea institute for structural maintenance and inspection
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• v.17 no.2
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• pp.1-9
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• 2013

In recent years, numerous mega-size and complex civil infrastructures have been constructed worldwide. For the more precise construction and maintenance process management of these civil infrastructures, the application of a variety of smart sensor-based structural health monitoring (SHM) systems is required. The efficient management of both sensors and collected databases is also very important. Recently, several kinds of database access technologies using Quick Response (QR) code and Augmented Reality (AR) applications have been developed. These technologies provide software tools incorporated with mobile devices, such as smart phone, tablet PC and smart pad systems, so that databases can be accessed very quickly and easily. In this paper, an AR-based structural health monitoring technique is suggested for sensor management and the efficient access of databases collected from sensor networks that are distributed at target structures. The global positioning system (GPS) in mobile devices simultaneously recognizes the user location and sensor location, and calculates the distance between the two locations. In addition, the processed health monitoring results are sent from a main server to the user's mobile device, via the RSS (really simple syndication) feed format. It can be confirmed that the AR-based structural health monitoring technique is very useful for the real-time construction process management of numerous mega-size and complex civil infrastructures.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.12
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• pp.20-29
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• 2014

Recently, LTE is preparing to make a new leap forward LTE-A all over the world. As LTE privides high speed service, the role of mobile phones seems to change from voice to data service. According to Cisco, global mobile data traffic will increase nearly 11-fold between 2013 and 2018. Mobile video traffic will reach 75% by 2018 from 66% in 2013 in Korea. However, voice service is still the most important role of mobile phones. Thus, controllability of throughput and low BLER is indispensable for high-quality VoIP service among various type of traffic. Although the maximum AMR-WB, 23.85 Kbps is sufficient to a VoIP call, it is difficult for the LTE which can provide tens to hundreds of MB/s may not keep the certain level VoIP QoS especially in the cell-edge area. This paper proposes a new scheduling algorithm in order to improve VoIP performance after analyzing various scheduling algorithms. The proposal is the technology which applies more priority processing for VoIP than other applications in cell-edge area based on two-tier scheduling algorithm. The simulation result shows the improvement of VoIP performance in the view point of throughput and BLER.

• Journal of Environmental Science International
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• v.25 no.10
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• pp.1349-1368
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• 2016

Concentrations of fine particulate matter ($PM_{2.5}$) and several of its particle constituents measured outside homes in Houston, Texas, and Los Angeles, California, were characterized using multiple regression analysis with proximity to point and mobile sources and meteorological factors as the independent variables. $PM_{2.5}$ mass and the concentrations of organic carbon (OC), elemental carbon (EC), benzo-[a]-pyrene (BaP), perylene (Per), benzo-[g,h,i]-perylene (BghiP), and coronene (Cor) were examined. Negative associations of wind speed with concentrations demonstrated the effect of dilution by high wind speed. Atmospheric stability increase was associated with concentration increase. Petrochemical source proximity was included in the EC model in Houston. Area source proximity was not selected for any of the $PM_{2.5}$ constituents' regression models. When the median values of the meteorological factors were used and the proximity to sources varied, the air concentrations calculated using the models for the eleven $PM_{2.5}$ constituents outside the homes closest to influential highways were 1.5-15.8 fold higher than those outside homes furthest from the highway emission sources. When the median distance to the sources was used in the models, the concentrations of the $PM_{2.5}$ constituents varied 2 to 82 fold, as the meteorological conditions varied over the observed range. We found different relationships between the two urban areas, illustrating the unique nature of urban sources and suggesting that localized sources need to be evaluated carefully to understand their potential contributions to $PM_{2.5}$ mass and its particle constituents concentrations near residences, which influence baseline indoor air concentrations and personal exposures. The results of this study could assist in the appropriate design of monitoring networks for community-level sampling and help improve the accuracy of exposure models linking emission sources with estimated pollutant concentrations at the residential level.

• The KIPS Transactions:PartC
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• v.19C no.2
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• pp.99-118
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• 2012

In PMIPv6-based network, mobile nodes can be made smaller and lighter because the network nodes perform the mobility management-related functions on behalf of the mobile nodes. The one of the protocols, Fast Handovers for Proxy Mobile IPv6(FPMIPv6)[1] has studied by the Internet Engineering Task Force(IETF). Since FPMIPv6 adopts the entities and the concepts of Fast Handovers for Mobile IPv6(FMIPv6) in Proxy Mobile IPv6(PMIPv6), it reduces the packet loss. Conventional scheme has proposed that it cooperated with an Authentication, Authorization and Accounting(AAA) infrastructure for authentication of a mobile node in PMIPv6, Despite the best efficiency, without begin secured of signaling messages, PMIPv6 is vulnerable to various security threats such as the DoS or redirect attAcks and it can not support global mobility between PMIPv. In this paper, we analyze Kang-Park & ESS-FH scheme, and then propose an Enhanced Security scheme for FPMIPv6(ESS-FP). Based on the CGA method and the pubilc key Cryptography, ESS-FP provides the strong key exchange and the key independence in addition to improving the weaknesses for FPMIPv6. The proposed scheme is formally verified based on Ban-logic, and its handover latency is analyzed and compared with that of Kang-Park scheme[3] & ESS-FH and this paper propose inter-domain fast handover sheme for PMIPv6 using proxy-based FMIPv6(FPMIPv6).

• International Commerce and Information Review
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• v.14 no.4
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• pp.317-337
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• 2012

This study has investigated shipping finance systems in Korea and China, and extracted negative factors based on it to propose a way to develop the shipping financial system in Korea for shipbuilding industry and marine transportation. From after the global financial crisis in 2008 to right before the Lehman Brothers Holdings bankruptcy, shipping finance has been dominated by the major industrialized countries in Europe. However, the weight point is moving to the countries in Asia region such as Korea, Japan, and China based on relatively strong banking system and low interests rate. This study focused on the alternatives the current situation that the starter of shipping finance among three countries in Northeast Asia, South Korea is facing China's challenges. In the paper, shipping finance in Korea presented its defectives such as the limits of ship financing, lack of professional workforces, ever-present foreign exchange risks, and lack of understandings of the parties. As the countermeasures of them, it proposed establishing professional institute for ship financing, training professionals in financial industry, raising foreign credentials of won, and continuing associations between the parties. Even though we are the first Asian country introduced ship funds, the ship funds growth in China shall be under our eyes while we keep systemic networks between shipping, ship building, and ship financing.

• Journal of Korea Port Economic Association
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• v.27 no.4
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• pp.73-90
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• 2011

Global companies regard the conditions of a location as one of the most crucial factors to assess the competitiveness of ports and the port hinterland, as well as emphasize creation of throughput and the importance of value added logistics in the hinterland under diffusing Supply Chain Management(SCM). This study deals with the evaluation of competitiveness in 7 hinterlands and the establishment of assessment model in hinterland. This study analyzes the importance of factors for the port hinterland competitiveness using AHP method. As a result, logistics factor, accounting for 62.3%, is shown as the relative more important factor, followed by hinterland's economy factors(27.3%) and city/policy factor(10.4%). The result implicates that measures to activate logistics factors with relatively high importance are essentially needed in order to improve the competitiveness of the hinterland of Busan New Port. Especially, it is needed to establish service routes of the port and air networks and to expand infrastructure for support. This study also assesses the competitiveness of hinterlands for the seven domestic and foreign ports based on importance of assessment factors for the hinterland competitiveness using AHP analysis. Busan(3.903) is ranked fourth behind Singapore(4.570), Hong Kong(4.357) and Shanghai(4.042) in assessment.

• Journal of the Korea Society of Computer and Information
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• v.21 no.6
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• pp.9-19
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• 2016

In finance literature, stock liquidity showing how stocks can be cashed out in the market has received rich attentions from both academicians and practitioners. The reasons are plenty. First, it is known that stock liquidity affects significantly asset pricing. Second, macroeconomic announcements influence liquidity in the stock market. Therefore, stock liquidity itself affects investors' decision and managers' decision as well. Though there exist a great deal of literature about stock liquidity in finance literature, it is quite clear that there are no studies attempting to investigate the stock liquidity issue as one of decision making problems. In finance literature, most of stock liquidity studies had dealt with limited views such as how much it influences stock price, which variables are associated with describing the stock liquidity significantly, etc. However, this paper posits that stock liquidity issue may become a serious decision-making problem, and then be handled by using data mining techniques to estimate its future extent with statistical validity. In this sense, we collected financial data set from a number of manufacturing companies listed in KRX (Korea Exchange) during the period of 2010 to 2013. The reason why we selected dataset from 2010 was to avoid the after-shocks of financial crisis that occurred in 2008. We used Fn-GuidPro system to gather total 5,700 financial data set. Stock liquidity measure was computed by the procedures proposed by Amihud (2002) which is known to show best metrics for showing relationship with daily return. We applied five data mining techniques (or classifiers) such as Bayesian network, support vector machine (SVM), decision tree, neural network, and ensemble method. Bayesian networks include GBN (General Bayesian Network), NBN (Naive BN), TAN (Tree Augmented NBN). Decision tree uses CART and C4.5. Regression result was used as a benchmarking performance. Ensemble method uses two types-integration of two classifiers, and three classifiers. Ensemble method is based on voting for the sake of integrating classifiers. Among the single classifiers, CART showed best performance with 48.2%, compared with 37.18% by regression. Among the ensemble methods, the result from integrating TAN, CART, and SVM was best with 49.25%. Through the additional analysis in individual industries, those relatively stabilized industries like electronic appliances, wholesale & retailing, woods, leather-bags-shoes showed better performance over 50%.