• Journal of the Korea Society for Simulation
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• v.13 no.1
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• pp.41-50
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• 2004

The purpose of this paper is to analyse the manager's policy to maximize the profit in a multiple-server queueing facility with a limited queue capacity. We assume that the level of advertizing effects on the arrival rate of customers to the facility. The model without ‘word of mouth effect’ is assumed that the arrival rate is independent on the qualify of service level. We estimate the service quality by the balking rate of customers from system. We extend this to the model with ‘word of mouth effect’. To achieve the maximum profit, the most important factor is the considerably high utilization of facility for both models. Given service rate, we should maintain an effective arrival rate to some extent. To this end, among the available options, an increase of advertizing effort is more desirable than reducing the fee if the service value of customers remains unchanged. We also investigate whether the variability of service time has a significant impact on determining the optimal policy. The cost of service variability is not so expensive as that in a single server model due to the reduced variability of service times in a multiple-server model.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.3
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• pp.575-580
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• 2008

Lately, the use of the NAT has become unavoidable with the increase of P2P traffic along with the exhaustion of IPv4 IP address. Due to NAT properties, NAT's internal host can only be connected through a relay method using the outside server. Accordingly, there is a lot of resource exhaustion of the relay server on the NAT exterior and network traffic increases. This essay proposes a topology that can form sessions to the NAT interior from the NAT exterior and that will decrease network traffic by placing NAT exterior relay servers in the NAT interior.

• International Journal of Computer Science & Network Security
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• v.24 no.8
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• pp.205-213
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• 2024

As the Restaurant industry is growing rapidly. The demand for an effortless POS (Point Of Sale) system which can make management easy is increasing. So, the purpose of this study is to digitalise the growing industry of restaurants and its consumers by utilizing cross-platform development. Crossplatform development frameworks provide great opportunities to solve the issues of handling ubiquitous devices with minimum efforts to reduce the cost and increase the stability, accessibility of the end consumers. By availing those opportunities, an Integrated POS system with cross platform is proposed. This integrated cross-platform POS system is originally designed for a single restaurant managed by its own private cloud server. This research solves the 2 major problems. One of them is the accessibility of the system on modern devices without even writing platform-specific code with the help of cross-platform development. This included web, mobile, desktops & tablets at the same time with the same codebase. Second one is handling data consistency with ubiquitous devices with the help of cloud infrastructure to make data safe and consistent more than ever. In the Development of this system Dart will be used as the primary programming language for cross-platform development. On the Cloud server system apache will be used as the web server and PHP as server side language. System will be using MySQL as the database server.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.2
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• pp.658-661
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• 2005

Internet-based client/server architecture of Contents Delivery System suffers from frequent disconnections and security treats caused by dependency of the server or overload. But, We reached the limit to the increase of the server because a contents quality enhance and Internet user explosively increase. Therefore, a P2P based computing methods are used for sloving these issues. In this paper, We implement and design the Education Content Delivery System for cyber education system using idle Computing Power in P2P computing to share computing resources. We implement not only Internet infrastructure but also satellite infrastructure system, and designed to transfer real-time or non real-time contents.

• Proceedings of the KIEE Conference
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• 2003.11b
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• pp.143-146
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• 2003

In mobile Internet banking service through wireless local area network, security is a most important factor to consider. We describe the development of mobile banking service using Personal Digatal Assistant (PDA). In order to increase the strength of encryption, we adopted hybrid approach where both of the public key algorithm and the secret key algorithm are used during the transaction among PDA, banking server and authentication server.

• Proceedings of the IEEK Conference
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• 2001.06e
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• pp.39-42
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• 2001

This paper proposes the design technique of memory sparing to overcome memory hard error Memory Sparing is used to increase the reliability and availability of commercial, military and space computer such as a Data Server, Communication Server, Flight Computer in airplane and On-Board Computer in spacecraft. But the documents about this technique are rare and hard to find. This paper has some useful information about memory error correction and memory error management.

• Journal of the Korea Society of Computer and Information
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• v.15 no.6
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• pp.57-64
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• 2010

Due to the limited storage space in video proxy server, it is often required to replace the old video data which is not serviced for long time with the newly requested video. This replacement causes the service delay and increase of network traffic. To circumvent this problem, we propose the an efficient replacement scheme in a video proxy server. In addition, we present a video data management technique for decreasing the number of replacement in video proxy server. For this purpose, we employ a memory in video proxy server. If the video segment which is loaded in memory is requested once again by a different user, this segment is resided in memory. The video in the memory is stored in the video proxy server depending on the consuming pattern by users. The simulation results show that the proposed algorithm performs better than other algorithms in terms of packet hit rate and number of packet replacement.

• Proceedings of the KSRS Conference
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• 2003.11a
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• pp.676-678
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• 2003

Recently, in according as rapid improvement of telecommunication markets and wireless internet technology, Location- Based Services (LBS) have been discussed as new 'Killer' application. The purpose of LBS is to determine location of user through mobile handset and to offer location information service to end-user. This paper has suggested an efficient transmission scheme of maps data as one of the important content services relating to data transmission of LBS in mobile environment. The basic system consists of three parts : (1) GIS (Geographic Information System) Server for storing, processing and handling map data, (2) Middleware Server for transmitting of map data by request of client, and (3) Client for requesting map data to Server and displaying them on handset. Also, in order to transmit map data, we are to expand WKB (Well Known Binary) in conformance to Simple Feature Specification of OGC (Open GIS Consortium), and increase efficiency of data transmission by developing trans mission data format to be able to transmit lightweight data and considering data compression technology.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2000.04a
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• pp.766-769
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• 2000

In recent years, Internet/Intranet represents the next generation of computing environment. Therefore, it is necessary to integrate WWW((World Wide Web) over internet/intranet and DBMS(Database Management System) in proportion to the increase of various users' request and an amount of data variety. Also, also full variety of service over WWW need to accomplish rapidly modification of bug and make a betterment of system according to a feature of rapid change of information and an importance of interaction with users. The typical CGI method commonly used to connect with database has a disadvantage in time and resources in system due to frequent connection with database. Therefore, this paper provides the conceptual structure and implementation of information management system over WWW with applying a recent information technology called ASP(Active Server Pages) that controls and arranges client logic dynamically in server-side and introducing a concept of working group and folder to database design.

• Journal of Communications and Networks
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• v.9 no.1
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• pp.43-49
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• 2007

The implementation of client polling as a weak cache coherence mechanism has two major drawbacks: Firstly, the cache may return a stale copy if the object is changed in the origin server while the cached copy is considered valid. Secondly, the cache can invalidate a cached copy that is still valid in the server. Therefore, we propose a multilevel pre-fetching (MLP) in conjunction with the client polling to refine these drawbacks. MLP is introduced to improve the level of freshness among the cached objects. The simulation results presented in this paper show that the proposed MLP significantly minimizes the number of stale objects and reduces the invalidation messages sent out to the server, i.e., increase the cache HIT rate.