• Spatial Information Research
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• v.22 no.1
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• pp.45-53
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• 2014

The purpose of this study is to design the GIS (Geographic Information System)-based BIM (Building Information Modeling) Objects Visualization System (OVS) Architecture by using Open source BIM Server Cost-Effectively. Recently, the studies related to the facility management using GIS and BIM are being researched world-widely. In this studies, it's important to develop the BIM Server to link the heterogeneous system such as GIS and represent GIS-based BIM objects. To implement it, the trends in related studies were reviewed and the open source-based BIM server architecture was analyzed. And then the architecture considering the BIM server was designed to represent the geometry and property of the BIM object which was stored in BIM server. Lastly, the system by using the proposed architecture was developed.

• Journal of Cadastre & Land InformatiX
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• v.44 no.1
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• pp.113-125
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• 2014

According to the public open data policy, the government established the demanders-oriented and customized open data plan and allowed people to use plenty of public data free. There are, however, few geospatial information systems to maximize its usability. For the purpose to make the effective geospatial information services, this study examined how data was linked between the public data portal and open platform first. And then this proposed the interface server model to support the data link between these systems technically.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.9B
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• pp.1073-1081
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• 2011

An URL parameter can hold some information that is confidential or vulnerable to illegitimate tampering. We propose Link-E-Param(Link with Encrypted Parameters) to protect the whole URL parameter names as well as their values. Unlike other techniques concealing only some of the URL parameters, it will successfully discourage attacks based on URL analysis to steal secret information on the Web sites. We implement Link-E-Param in the form of a servlet filter to be deployed on any Java Web server by simply copying a jar file and setting a few configuration values. Thus it can be used for any existing Web application without modifying the application. It also supports numerous encryption algorithms to choose from. Experiments show that our implementation induces only 2~3% increase in user response time due to encryption and decryption, which is deemed acceptable.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.7 no.1
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• pp.22-37
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• 2013

Content distribution to a large number of concurrent clients stresses both server and network. While the server limitation can be circumvented by deploying server clusters, the network limitation is far less easy to cope with, due to the difficulty in measuring and balancing network load. In this paper, we use two useful network load metrics, the worst link stress (WLS) and the degree of interference (DOI), and formulate the problem as partitioning the clients into disjoint subsets subject to the server capacity constraint so that the WLS and the DOI are reduced for each session and also well balanced across the sessions. We present a network load-aware partition algorithm, which is practicable and effective in achieving the design goals. Through experiments on PlanetLab, we show that the proposed scheme has the remarkable advantages over existing schemes in reducing and balancing the network load. We expect the algorithm and performance metrics can be easily applied to various Internet applications, such as media streaming, multicast group member selection.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.4
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• pp.1768-1789
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• 2016

In contemporary video streaming systems based on HTTP protocol, video players at the client side are responsible for adjusting video quality to network conditions and user expectations. However, when multiple video clips are streamed simultaneously, an intricate application logic implemented in the video players overlays the TCP mechanism which is responsible for a balanced access to a shared network link. As a result, some video players may not obtain a fair share of network throughput and may be vulnerable to an unstable video bit-rate. Therefore, we propose to simplify the algorithms implemented in the video players, which are responsible for the adjustment of video quality and constrain their functionality only to sending feedback to a server about a state of the player buffer. The main logic of the system is shifted to the server, which is now responsible for bit-rate selection and prioritisation of the video streams transmitted to multiple clients. To verify our proposition, we performed several experiments in a laboratory environment which show that when the server cooperates with the clients, the video players experience fewer quality switches and the system achieves better fairness when allocating network throughput among the video players. However, this comes at the cost of worse utilisation of network bandwidth.

• The Journal of Society for e-Business Studies
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• v.9 no.1
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• pp.285-301
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• 2004

Public service provision through internet is one of major parts for e-government implementation. It is essential to link the internal administrative network with internet to provide the services through internet and to support kiosks through internet, which should result in critical issues for security. A relay server, as a front server for the public service processing system and a web server, a control server for kiosks, are placed between the public service processing system and kiosks to solve those security issues. It is the way to solve security issues through protecting direct communication between the public service processing system and a web server and authenticating a relay server and a web server through authentication process. In the implementation of the system this paper provide a design for an architecture model of the public service processing system through internet, which are aiming to develop high level of the quality system effectively, to reduce the risk of initial stage of development, and to reduce the incurring cost due to reworks.

• The Transactions of the Korea Information Processing Society
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• v.4 no.8
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• pp.2080-2091
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• 1997

It is generally recognized that Video On Demand (VOD) service will become a promising interactive service in the emerging broadband integrated services digital networks. A centralized VOD system, all programs are stored in a single VOD server which is linked to each user via exchanges, is applicable when a small number of users enjoys the VOD service. However, in case of large service penetration, it is very important to solve the problems of bandwidth and load concentrating in the central video server(CVS) and program transmission network. In this paper, the architecture of the video distribution service network is studied, then a traffic characteristics and models for VOD system are established, and proposed program allocation method to video servers. For this purpose, we present an analysis of program storage amount in each LVS(Local Video Server), transmission traffic volume between LVSs, and link traffic volume between CVS and LVSs, according to changing the related factors such as demand, the number of LVS, vision probability, etc. A method for finding out storage capacity in LVSs is also presented on the basis of the tradeoffs among program storage cost, link traffic cost, and transmission cost.

• Journal of Communications and Networks
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• v.4 no.4
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• pp.266-281
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• 2002

The General Packet Radio Service (GPRS) is being deployed by GSM network operators world-wide, and promises to provide users with “always-on” data access at bandwidths comparable to that of conventional fixed-wire telephone modems. However, many users have found the reality to be rather different, experiencing very disappointing performance when, for example, browsing the web over GPRS. In this paper, we examine the causes, and show how unfortunate interactions between the GPRS link characteristics and TCP/IP protocols lead to poor performance. A performance characterization of the GPRS link-layer is presented, determined through extensive measurements taken over production networks. We present measurements of packet loss rates, bandwidth availability, link stability, and round-trip time. The effect these characteristics have on TCP behavior are examined, demonstrating how they can result in poor link utilization, excessive packet queueing, and slow recovery from packet losses. Further, we show that the HTTP protocol can compound these issues, leading to dire WWW performance. We go on to show how the use of a transparent proxy interposed near the wired-wireless border can be used to alleviate many of these performance issues without requiring changes to either client or server end systems.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.5 no.4
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• pp.720-740
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• 2011

Wi-Fi-enabled portable devices have recently been introduced into the consumer electronics market. These devices download or upload content, from or to a host machine, such as a personal computer, a laptop, a home gateway, or a media server. This paper investigates the fairness among multiple Wi-Fi-enabled portable devices in a home network when they are simultaneously communicated with the host machine. First, we present that, a simple IEEE 802.11-based home network suffers from unfairness, and the fairness is exaggerated by the wireless link errors. This unfairness is due to the asymmetric response of the TCP to data-packet loss and to acknowledgment-packet loss, and the wireless link errors that occur in the proximity of any node; the errors affect other wireless devices through the interaction at the interface queue of the home gateway. We propose a QoS-provisioning framework in order to achieve per-device fairness and service differentiation. For this purpose, we introduce the medium access price, which denotes an aggregate value of network-wide traffic load, per-device link usage, and per-device link error rate. We implemented the proposed framework in the ns-2 simulator, and carried out a simulation study to evaluate its performance with respect to fairness, service differentiation, loss and delay. The simulation results indicate that the proposed method enforces the per-device fairness, regardless of the number of devices present and regardless of the level of wireless link errors; furthermore it achieves high link utilization with only a small amount of frame losses.

• Journal of the Korea Society of Computer and Information
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• v.17 no.5
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• pp.49-57
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• 2012

In P2P streaming management, peer's churning and finding efficient topology architecture optimization algorithm that reduces streaming delay is important. This paper studies a topology optimization algorithm based on the P2P streaming using peer's link information. The proposed algorithm is based on the estimation of peer's upload bandwidth using peer's link information on mesh-network. The existing algorithm that uses the information of connected links is efficient to reduce message overload in the point of resource management. But it has a risk of making unreliable topology not considering upload bandwidth. And when some network error occurs in a server-closer-peer, it may make the topology worse. In this paper we propose an algorithm that makes up for the weak point of the existing algorithm. We compare the existing algorithm with the proposed algorithm using test data and analyze each simulation result.