• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.41 no.10
• /
• pp.1256-1262
• /
• 2016

As the population of camping is increased in campsites and auto camp sites, the electrical equipment can safely supply electricity to users in a variety of electricity bill policy is required in the campsite. In this paper, we develop the vending machine for electricity that can control the outdoor electrical outlet from the management server using the Z-Wave WPAN and android mobile application. The developed vending machine for electricity consists of the management server, the controller, the outdoor outlet box, and the mobile application. The management server provides reservation and electricity bill payment to users. The management server controls the electrical outlet box through the controller to safely supply electricity to users. The controller that is a relay device between the management server and the switch controls switches based on Z-Wave mesh network. Outdoor electrical outlet box has 2 meter switches. We receive the relevant authorization to provide commercial electricity services using the outdoor electrical outlet box in the campsite.

• The KIPS Transactions:PartA
• /
• v.8A no.4
• /
• pp.287-292
• /
• 2001

Multimedia service systems should have efficient capacity to serve the growing clients and new data. In the general streaming services, users can endure the small amount of time delay at the beginning of service. But they want to have good quality of service. A streaming server tries to transfer video files to clients from a repository of files in real time. The server must guarantee concurrent and uninterrupted delivery of each video stream requested from clients. To achieve its purpose, many stream servers adopt multi-processors, sufficient memory, and RAID or SAN in their systems. In this paper, we propose a Linux-based parallel media streaming server. It is superior to the other systems in the storing structure, fault-tolerance, and service capacity. Since this system supports the web interlace, users can operate easily through the www. This system uses unique striping policy to distribute multimedia files into the parallel storage nodes. If a service request occurs, each storage node transmits striped files concurrently to the client. Its performance is better than the single media streaming service because of the parallel architecture.

• Journal of Digital Convergence
• /
• v.17 no.2
• /
• pp.155-161
• /
• 2019

Electroencephalography (EEG), a representative method of identifying temporal and spatial changes in brain activity, is a voluntary electrical activity measurable in the human scalp. Various interface technologies have been provided to control EEG activity, and it is possible to operate a machine such as a wheelchair or a robot through brainwaves. The characteristics of EEG data are collected in various types of channels in real time, and a server system for analyzing them is required to have an independent and lightweight system for the platform. In these days, the Spring platform is used as a large business server as an independent, lightweight server system. In this paper, we propose an EEG analysis system using the Spring server system. Using the proposed system, the reliability of EEG control can be enhanced, and analysis and control interface expansion can be provided in various aspects such as game and medical areas.

• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.38 no.1
• /
• pp.21-29
• /
• 2015

A steady-state controllable M/G/1 queueing model operating under the {T:Min(T,N)} policy is considered where the {T:Min(T,N)} policy is defined as the next busy period will be initiated either after T time units elapsed from the end of the previous busy period if at least one customer arrives at the system during that time period, or after T time units elapsed without a customer' arrival, the time instant when Nth customer arrives at the system or T time units elapsed with at least one customer arrives at the system whichever comes first. After deriving the necessary system characteristics including the expected number of customers in the system, the expected length of busy period and so on, the total expected cost function per unit time for the system operation is constructed to determine the optimal operating policy. To do so, the cost elements associated with such system characteristics including the customers' waiting cost in the system and the server's removal and activating cost are defined. Then, procedures to determine the optimal values of the decision variables included in the operating policy are provided based on minimizing the total expected cost function per unit time to operate the queueing system under considerations.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.28 no.10C
• /
• pp.1033-1044
• /
• 2003

In this paper, we propose security management architecture that manages efficiently security systems that are produced by different companies and programmable middleware that can reduce the load of management traffic. The proposed architecture applies programmable networks technology to policy based network management (PBNM). The proposed architecture manages and cooperates various security systems using security policy. Also, the programmable middleware provides convenience of management and reduces the overhead of a policy server by translating security policy into execution command. In addition, using programmable middleware, an administrator can manage various security systems that are produced by different companies. We showed that the programmable middleware could reduce the load of management traffic by comparing processing time for enforcing and transferring of policies/messages between the proposed architecture and PBNM architecture.

• Journal of applied mathematics & informatics
• /
• v.8 no.1
• /
• pp.199-212
• /
• 2001

We consider a k-out-of-n system with repair under T-policy. Life time of each component is exponentially distributed with parameter $\lambda$. Server is called to the system after the elapse of T time units since his departure after completion of repair of all failed units in the previous cycle or until accumulation of n-k failed units, whichever occurs first. Service time is assumed to be exponential with rate ${\mu}$. T is also exponentially distributed with parameter ${\alpha}$. System state probabilities in finite time and long run are derived for (i) cold (ii) warm (iii) hot systems. Several characteristics of these systems are obtained. A control problem is also investigated and numerical illustrations are provided. It is proved that the expected profit to the system is concave in ${\alpha}$ and hence global maximum exists.

• Proceedings of the Korean Statistical Society Conference
• /
• 2004.11a
• /
• pp.295-300
• /
• 2004

We consider a G/M/1 queue with two-stage service policy. The server starts to serve with rate of ${\mu}1$ customers per unit time until the number of customers in the system reaches A. At this moment, the service rate is changed to that of ${\mu}2$ customers per unit time and this rate continues until the system is empty. We obtain the stationary distribution of the number of customers in the system.

• Journal of Korean Institute of Industrial Engineers
• /
• v.33 no.4
• /
• pp.419-423
• /
• 2007

In this paper, we consider the M/G/1 queueing system with randomized control of T-policy. Whenever the busy period ends, the server is turned off and takes multiple vacations whose interval is fixed time T with probability p or stays on and waits for arriving customers with probability 1-p. We introduce the cost function and determine the optimal combination of (p, T) to minimize the average cost per unit time.

• Journal of the Korean Operations Research and Management Science Society
• /
• v.32 no.1
• /
• pp.53-60
• /
• 2007

We consider the discrete-time $Geo^x/G/1$ queues under N-policy with multiple vacations (a single vacation) and setup time. In this queueing system, the server takes multiple vacations (a single vacation) whenever the system becomes empty, and he begins to serve the customers after setup time only if the queue length is at least a predetermined threshold value N. Using the heuristic approach, we derive the mean waiting time for both vacation models. We demonstrate that the heuristic approach is also useful for the discrete-time queues.

• Management Science and Financial Engineering
• /
• v.12 no.2
• /
• pp.1-18
• /
• 2006

We consider an $M^x/G/1$ queueing system with Bernoulli vacation schedule under multiple vacation policy. where after each vacation completion or service completion the server takes sequence of vacations until a batch of new customer arrive. This generalizes both $M^x/G/1$ queueing system with multiple vacation as well as M/G/1 Bernoulli vacation model. We carryout an extensive analysis for the queue size distributions at various epochs. Further attempts have been made to unify the results of related batch arrival vacation models.