• KIISE Transactions on Computing Practices
• /
• v.22 no.12
• /
• pp.675-680
• /
• 2016

The development of various mobile devices and mobile platform technology has led to a steady increase in the number of online social network (OSN) users. OSN users are free to communicate and share information through activities such as social networking, but this causes a new, user privacy issue. Various distributed OSN architectures are introduced to address the user privacy concern, however, users do not obtain technically perfect control over their data. In this study, the control rights of OSN user are maintained by using personal data storage (PDS). We propose a technique to improve data privacy protection that involves making a group with the user's friend by generating and providing fake text data based on user's real text data. Fake text data is generated based on the user's word sensitivity value, so that the user's friends can receive the user's differential data. As a result, we propose a system architecture that solves possible problems in the tradeoff between service utility and user privacy in OSN.

• Journal of Navigation and Port Research
• /
• v.33 no.6
• /
• pp.457-462
• /
• 2009

In this paper we suggest optimal positioning algorithm for DER(distributed energy resource)s near ocean side by using Newton-Rhapson load flow calculation. By installing DERs within urban area, electric power can be effectively transmitted to each loads without constructing additional large scale power stations and transmission lines. Therefore, DERs have attracted worldwide attention as urban area energy sources. However, there are quite a few studies for estimation of power loss due to DERs' location change within urban area Hence, in this study, an optimal positioning scheme for DERs is proposed in order to minimizing electrical power loss.

• Journal of IKEEE
• /
• v.24 no.1
• /
• pp.311-318
• /
• 2020

A virtual power plant is a kind of software power plant that enables participation in power operation by integrally managing individual distributed resources. This paper proposes a common information communication architecture based on the TASE.2 standard and the OpenADR2.0 standard to operate a virtual power plant as a single power system. ESS is designed TASE.2 SBO devices that related objects are mapped to OpenADR2.0 services and composed as a single sequence type. Through simulation verification, it conforms data exchange and operation based on both standards.

• ETRI Journal
• /
• v.42 no.5
• /
• pp.643-657
• /
• 2020

Sixth generation will exploit satellite, aerial, and terrestrial platforms jointly to improve radio access capability and unlock the support of on-demand edge cloud services in three-dimensional (3D) space, by incorporating mobile edge computing (MEC) functionalities on aerial platforms and low-orbit satellites. This will extend the MEC support to devices and network elements in the sky and forge a space-borne MEC, enabling intelligent, personalized, and distributed on-demand services. End users will experience the impression of being surrounded by a distributed computer, fulfilling their requests with apparently zero latency. In this paper, we consider an architecture that provides communication, computation, and caching (C3) services on demand, anytime, and everywhere in 3D space, integrating conventional ground (terrestrial) base stations and flying (non-terrestrial) nodes. Given the complexity of the overall network, the C3 resources and management of aerial devices need to be jointly orchestrated via artificial intelligence-based algorithms, exploiting virtualized network functions dynamically deployed in a distributed manner across terrestrial and non-terrestrial nodes.

• The KIPS Transactions:PartC
• /
• v.9C no.1
• /
• pp.79-88
• /
• 2002

Transcoding proxy strategy has been widely used as a means to reduce the delay in retrieving Web pages over wireless mobile data service networks. However, this strategy has the serious drawbacks of being a potential point of failure or a bottleneck of the service. We developed a distributed proxy server system in which multiple proxy servers are installed at geographically dispersed locations and share the workloads among them by serving mobile hosts only within assigned regions. A new handoff message protocol to enable handoffs between proxies as the mobile hosts move between regions is proposed. According to the proxy server handoff protocol, a client agent at the mobile horst requests a proxy server to start handoff processing by which two proxy servers synchronize distilled data belonging to a HTTP session that must be maintained across the handoff. Also, we introduce the architecture of the proxy server and the client agent that handles the proxy server handoff. Finally, we evaluate the proposed system through performance test.

• Journal of the Korean Society of Environmental Restoration Technology
• /
• v.7 no.2
• /
• pp.52-61
• /
• 2004

This study has been carried out to classify forest vegetation in south and north slopes of Donghaksa valley for supplying basic data for conservation and restoration of the valley. With the phytosociological method, the forest of the south and north slopes of Donghaksa valley was classified as four groups; Quercus variabilis community, Quercus mongolica community, Pinus densiflora community and Carpinus laxiflora community. The dominant species were found in the order of Pinus densiflora, Quercus variabilis, Carpinus laxiflora, and Quercus mongolica. Comparing the north and south slopes, Quercus variabilis were the highest dominant species in the south and Carpinus laxiflora in the north. Pinus densiflora were the next dominant species in both south and north slopes. According to the DBH analysis result, Pinus densiflora and Quercus variabilis had density of normal distribution style among the entire community. Therefore, their dominance are expected to continue for now. But, Quercus mongolica and Carpinus laxiflora are expected to extend their influence in the future in terms of competition with Pinus densiflora. The correlation between each community and the environment according to DCCA ordination was examined in this study. The result told us that Quercus variabilis is distributed mainly on the south slope in a mid-steep and mid-altitude area. Quercus mongolica community appeared on the north slope in the steep high-altitude area that has high percentage in total nitrogen and CEC. Pinus densiflora community is distributed on both south and north slopes in a gentle slope and low-altitude area. Carpinus laxiflora is distributed on the north slope in a mid-steep and mid-altitude area.

• Korean Journal of Environment and Ecology
• /
• v.30 no.3
• /
• pp.376-385
• /
• 2016

Through the vegetation survey of Geumcheon Valley on the south-facing slope and the other side of the valley, Jedanggol on the north-facing slope in Taebaeksan Provincial Park, the characteristics of vegetation structure and change by slope and altitude were examined. From Geumcheon Valley(850m) via the ridge(1,380m) to Jedanggol(950m), thirty plots at intervals of 50m altitude were selected for investigation. According to the results of the analysis, Acer pictum subsp. mono, Fraxinus rhynchophylla, Betula davurica and Lindera obtusiloba were observed only in the south-facing slope, while Sorbus commixta, Prunus padus, Prunus maackii and Acer komarovii were observed only in the north-facing slope. However, Quercus mongolica, Betula costata, Cornus controversa, Tilia amurensis, Acer pseudosieboldianum and Magnolia sieboldii were found to be distributed over both the slopes. The analysis of ordination found that the vegetation was distributed discontinuously by slope. Especially, the vegetation of the north-facing slope appeared to be affected by the direction that the slope faces. Quercus mongolica community, which is the dominant species at an altitude of over 1,200m, was determined to be affected by elevation factor. The maximum age of the major trees was as follows: Betula costata and Quercus mongolica were estimated to be 53-year-old and 113-year-old respectively.

• Journal of Environmental Science International
• /
• v.14 no.9
• /
• pp.817-825
• /
• 2005

The purpose of this study was to research about salt marsh flora and vegetation in the Dongjin-river estuary area where has a project for Sea Man Geum Reclaimed Land so that we can foster foundation on restoration of an ecological habitat, development of applicable plant and establishment of a conservation policy after deceloping the reclaimed land for salt marsh vegetation which has great value ecologically. In conclusion, we was distributed that there are 7 families 21 genera, 25 species, 2 varieties of vascular plant at the Dongjin-river estuary area which have 27 taxa in total and are $0.64\%$ among 4,191 of korean vascular plant. There are also 2 family, 2 genus, 2 species of a naturalized plant which are $1.1\%$ of indicator of a naturalized plant salt marsh vegetation of the downstream are very much affected by the time of inundation, tidal water so that a low degree of salt marsh has frequent flooding by sea water and has a pure group of Suaeda japonica. A Phragmites communis, Carex scabrifolia are distributed mainly around a waterway of salt marsh and Zoysia sinica, Atriplex subcordata, Phragmites communis are living in stock as forming into patch around medium salt marsh. Suaeda asparagoides, Phacelurus latifolius are living around a little high ground and a Phragmites communis is a behind vegetation of Phacelurus latifolius and a part of the Phragmites communis are living along with waterway in a salt marsh as a community. By the 2-M method twelve plant communities were recognized ; Suaeda japonica. Carex scabrifolia, Zoysia sinica, Artemisia scoparia, Phacelurus latifolius, Phragmites communis, Suaeda maritima, Suaeda japonica-Atriplex gmelini, Phragmites communis-Suaeda japonica, Suaeda japonica-Salicornia herbacea, Salicornia herbacea-Suaeda aspar-agoides and Scirpus planiculmis community. The actual vegetation map was constructed on the grounds of the communities classified and other data.

• Journal of KIISE:Information Networking
• /
• v.31 no.6
• /
• pp.582-594
• /
• 2004

In school PC labs or other educational purpose PC labs with a few dozens of PCs, computers are configured in a distributed architecture so that they are set up, maintained and upgraded separately. As an alternative to the distributed architecture, we can consider a thin-client computing environment. In a thin-client computing environment, client side devices provide mainly I/O functions with user friendly GUI and multimedia processing support whereas remote servers called terminal server provide computing power. In order to support many clients in the environment, a cluster of terminal servers can be configured. In this architecture, it is difficult due to the characteristics of terminal session persistence and different pattern of computing usage of users so that the utilization of terminal server resources becomes low. To overcome this disadvantage, we propose an adaptive terminal cluster where terminal servers ,ire partitioned into groups and a terminal server in a light-loaded group can be dynamically reassigned to a heavy-loaded group at run time. The proposed adaptive scheme is compared with a generic terminal service cluster and a group based non-adaptive terminal server cluster. Experimental results show the effectiveness of the proposed scheme.

• Journal of Korea Spatial Information System Society
• /
• v.8 no.2 s.17
• /
• pp.75-89
• /
• 2006

LBS (Location-Based Service) systems have become a serious subject for research and development since recent rapid advances in wireless communication technologies and position measurement technologies such as global positioning system. The architecture named the GALIS (Gracefully Aging Location Information System) has been suggested which is a cluster-based distributed computing system architecture to overcome performance losses and to efficiently handle a large volume of data, at least millions. The GALIS consists of SLDS and LLDS. The SLDS manages current location information of moving objects and the LLDS manages past location information of moving objects. In this thesis, we implement a monitoring technique for the GALIS prototype, to allow dynamic load balancing among multiple computing nodes by keeping track of the load of each node in real-time during the location data management and spatio-temporal query processing. We also propose a buffering technique which efficiently manages the query results having overlapped query regions to improve query processing performance of the GALIS. The proposed scheme reduces query processing time by eliminating unnecessary query execution on the overlapped regions with the previous queries.