• The Journal of Engineering Research
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• v.7 no.1
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• pp.29-36
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• 2005

In multi-server environment, We have to design a mechanism that selects appropriate servers for processing each service request while maximizing server throughput and minimizing average response of service requests. In this paper, we propose a job scheduling method for courseware delivery system using a idle computing resources on LAN. The proposed scheduling method propose an approach that uses client service request time, server available period and server load of requested service as guidelines of server selection. Comparing the our approach method to conventional one, experiments that the proposed approach provides better performance.

• Industrial Engineering and Management Systems
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• v.15 no.2
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• pp.131-142
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• 2016

We consider a multi-server queueing system without buffer and with two types of customers as a model of operation of a mobile network cell. Customers arrive at the system in the marked Markovian arrival flow. The service times of customers are exponentially distributed with parameters depending on the type of customer. A part of the available servers is reserved exclusively for service of first type customers. Customers who do not receive service upon arrival, can make repeated attempts. The system operation is influenced by random factors, leading to a change of the system parameters, including the total number of servers and the number of reserved servers. The behavior of the system is described by the multi-dimensional Markov chain. The generator of this Markov chain is constructed and the ergodicity condition is derived. Formulas for computation of the main performance measures of the system based on the stationary distribution of the Markov chain are derived. Numerical examples are presented.

• Journal of the Semiconductor & Display Technology
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• v.3 no.4
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• pp.13-17
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• 2004

As the usage of wireless LAN becomes common in working environment, the number of database systems that support both wired and wireless users increases rapidly. The characteristics of wireless LAN that its speed is slow relatively comparing to wired network and the users in its environment connects to different communication points as they moves creates another challenge to be resolved in database systems. In the environment of hybrid communication systems, wired and wireless for voluminous data amount and a number of users, the two layer architecture of the conventional client-server database systems has limitation in the system performance. This is due to that server is the only point of data service in client-server database systems. In this paper, we discuss a new extended database system architecture that data services are distributed among servers and clients based on user database access patterns in order to improve system performance. We analyze the expected system performance by using simulation technique and prove the practical utilization of the system by demonstrating experimental results.

• 대한공업교육학회지
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• v.33 no.1
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• pp.265-281
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• 2008

The objective of this study is to show practice example let student experience about concurrent servers based multi-processes and multi-thread among the principles of data communication in ICT(information and communications technology). For this, we first implement multi-process server(fork server) and multi-thread server(thread server), and multi-thread client(thread client), Secondly, for experimental environment, we developed small ethernet networks and measure data transfer time with relation to the number of users. Experimental results show that mean transfer time of thread server is less than that of fork server by 20~61 % on average. Furthermore, it is found that the difference of data transfer time between fork server and thread server is proportional to that of the number of users. Main reason of performance difference dues to the difference between process forking time and thread creation time. We can also find that context switching for process and thread affects the load of web server. Our presentation and experimental results can be applied to used as the educational practice materials with which student can experience data communication principles.

• Journal of Korea Society of Industrial Information Systems
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• v.7 no.1
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• pp.16-26
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• 2002

A web based mail system consists of servers and clients. A server side takes charge of making rail accounts and service, a client side does interfacing with users. In this paper, we designed the mail system with multi-domain facility. Also we implemented both a ussr environment based on the internet explorer and management environment based on the windows server 2000. Using the service engine of rail system, we could provide the user efficiency through responding user absence, automatic mail sorting, verifying receipt and refusing messages, and implemented the rail system which provides the reliable system.

• Journal of Information Processing Systems
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• v.17 no.3
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• pp.615-629
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• 2021

With the development of mobile edge computing, how to utilize the computing power of edge computing to effectively and efficiently offload data and to compute offloading is of great research value. This paper studies the computation offloading problem of multi-user and multi-server in mobile edge computing. Firstly, in order to minimize system energy consumption, the problem is modeled by considering the joint optimization of the offloading strategy and the wireless and computing resource allocation in a multi-user and multi-server scenario. Additionally, this paper explores the computation offloading scheme to optimize the overall cost. As the centralized optimization method is an NP problem, the game method is used to achieve effective computation offloading in a distributed manner. The decision problem of distributed computation offloading between the mobile equipment is modeled as a multi-user computation offloading game. There is a Nash equilibrium in this game, and it can be achieved by a limited number of iterations. Then, we propose a distributed computation offloading algorithm, which first calculates offloading weights, and then distributedly iterates by the time slot to update the computation offloading decision. Finally, the algorithm is verified by simulation experiments. Simulation results show that our proposed algorithm can achieve the balance by a limited number of iterations. At the same time, the algorithm outperforms several other advanced computation offloading algorithms in terms of the number of users and overall overheads for beneficial decision-making.

• Journal of Korea Game Society
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• v.2 no.2
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• pp.113-119
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• 2002

With development of internet technology, digital economy that advance rapidly formed much leagues of B2B, B2C, A2B etc, according to the application part. Also, electronic commerce system implementation technology is introduced by Component based on development method in object oriented technique base depending on customer's requirement, and development environment changes by 3- Tiers, Web-Based architecture etc. in existent C/S (Client/Server) environment and is introduced. Thus, In this research, I implemented seat reservation and confirmation system that can be used in electronic commerce in multi-server environment. This, for improve efficiency in distribute environment, relevant importance logic used server component model EJB, and implemented through JSP and Java that use Servlet of Resin Server environment for Main Server. Therefore, through independence component using EJB, I did so that can improved independence between electronic commerce system logic, and reduce server's overhead calling relevant method through discrete EJB server, and manage each logic resources efficiently.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.2
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• pp.924-944
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• 2017

Telecare Medical Information System (TMIS) helps the patients to gain the health monitoring information at home and access medical services over the mobile Internet. In 2015, Das et al proposed a secure and robust user AKA scheme for hierarchical multi-medical server environment in TMIS, referred to as DAKA protocol, and claimed that their protocol is against all possible attacks. In this paper, we first analyze and show DAKA protocol is vulnerable to internal attacks, impersonation attacks and stolen smart card attack. Furthermore, DAKA protocol also cannot provide confidentiality. We then propose a lightweight pseudonym AKA protocol for multi-medical server architecture in TMIS (short for PAKA). Our PAKA protocol not only keeps good security features declared by DAKA protocol, but also truly provides patient's anonymity by using pseudonym to protect sensitive information from illegal interception. Besides, our PAKA protocol can realize authentication and key agreement with energy-saving, extremely low computation cost, communication cost and fewer storage resources in smart card, medical servers and physical servers. What's more, the PAKA protocol is proved secure against known possible attacks by using Burrows-Abadi-Needham (BAN) logic. As a result, these features make PAKA protocol is very suitable for computation-limited mobile device.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38B no.3
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• pp.190-198
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• 2013

Since the facilities for the remote users tend to be deployed in distributed manner, authentication schemes for multi-server communication settings, which provide various web services, are required for real-world applications. A typical way to authenticate a remote user relies on password authentication mostly. However, this method is vulnerable to attacks and inconvenient as the system requires users to maintain different identities and corresponding passwords. On the other hand, the user can make use of a single password for all servers, but she may be exposed to variants of malicious attacks. In this paper, we propose an efficient and secure authentication scheme based on a brokered authentication along with smart-cards in multi-server environment. Further we show that our scheme is secure against possible attacks and analyze its performance with respect to communication and computational cost.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.12C
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• pp.1021-1028
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• 2008

In a network environment, when a user requests a server's service, a remote user authentication system using smart cards is a very practical solution to validate the eligibility of a user and provide secure communication. In these authentication schemes, due to fast progress of networks and information technology, most of provided services are in multi-server environments. However, there are no studies in multi-server authentication schemes using smart cards providing mutual anonymity so far. In this paper, we propose a novel user authentication scheme using smart cards providing mutual authentication and mutual anonymity for multi-server environments. Our proposed scheme achieves the low-computation requirement for smart cards and a user can use permitted various services in eligible servers by only one registration. Also, this scheme guarantees perfect mutual anonymity of participants.