• The Journal of Society for e-Business Studies
• /
• v.4 no.1
• /
• pp.87-101
• /
• 1999

To operate the automatic devices of manufacturing process more effectively and to solve the needs of the resource sharing, network technology is applied to the control devices located in common manufacturing zone and operated by connecting them. In this paper, functional standard of the network layers are set as physical and data link layer of IEEE 802.2, 802.4, and VMD application layer and ISO-CIM reference model. Then, they are divided as minimized architecture, designed as group objects which perform group management and service objects which organizes and operates the group. For the stability in this network, this paper measures the variation of data packet length and node number and analyzes the variated value of the waiting time for the network operation. For the method of the analysis, non-exhausted service method are selected, and the arrival rates of the each data packet to the nodes that are assumed to form a Poission distribution. Then, queue model is set as M/G/1, and the analysis equation for waiting time is found. For the evalution of the performance, the length of the data packet varies from 10 bytes to 100 bytes in the operation of the group management network, the variation of the wating time is less than 10 msec. Since the waiting time in this case is less than 10 msec, response time is fast enough. Furthermore, to evaluate the real time processing of the group management network, it shows if the number of nodes is less than 40, and the average arrival time is less than 40 packet/sec, it can perform stable operation even taking the overhead such as software delay time, indicated packet service, and transmissin safety margin.

• Journal of the Korean Operations Research and Management Science Society
• /
• v.22 no.2
• /
• pp.1-12
• /
• 1997

We consider an M/M/2 queue with two servers placed in series. System performance measures that we present in closed expressions are the first and the second moments for the system size, the queue walting time and the sojourn time. We also present an algorithm for computing the queue waiting time distribution function based on the randomization method. As an application, we analyze the double tollbooth system and compare its performance with the conventional single tollbooth system's.

• Journal of the Institute of Electronics Engineers of Korea CI
• /
• v.37 no.2
• /
• pp.44-53
• /
• 2000

The waiting delays of users are inevitable in this policy since the services are not taken immediately upon requests but upon every scheduling points. An inefficient management of such delays makes an unfair service to users and increases the possibility of higher reneging rates. This paper proposes an adaptive batch scheduling scheme which improves the average waiting time of users requests and reduces the starvation problem of users requesting less popular movies. The proposed scheme selects dynamically multiple videos in given intervals based on the service patterns which reflect the popularity distribution(Zipf-distribution) and resource utilizations. Experimental results of simulations show that the proposed scheme improves about 20-30 percentage of average waiting time and reduces significantly the starving requesters comparing with those of conventional methods such as FCFS and MQL.

• Bulletin of the Korean Chemical Society
• /
• v.26 no.11
• /
• pp.1723-1727
• /
• 2005

A generalized fractional diffusion equation (FDE) is presented, which describes the time-evolution of the spatial distribution of a particle performing continuous time random walk (CTRW) on a fractal lattice. For a case corresponding to the CTRW with waiting time distribution that behaves as $\psi(t) \sim (t) ^{-(\alpha+1)}$, the FDE is solved to give analytic expressions for the Green’s function and the mean squared displacement (MSD). In agreement with the previous work of Blumen et al. [Phys. Rev. Lett. 1984, 53, 1301], the time-dependence of MSD is found to be given as < $r^2(t)$ > ~ $t ^{2\alpha/dw}$, where $d_w$ is the walk dimension of the given fractal. A Monte-Carlo simulation is also performed to evaluate the range of applicability of the proposed FDE.

• Communications of the Korean Mathematical Society
• /
• v.14 no.3
• /
• pp.611-625
• /
• 1999

We consider ΜΑΡ/G/ 1 finite capacity queue with mul-tiple thresholds on buffer. The arrival of customers follows a Markov-ian arrival process(MAP). The service time of a customer depends on the queue length at service initiation of the customer. By using the embeded Markov chain method and the supplementary variable method, we obtain the queue length distribution ar departure epochs and at arbitrary epochs. This gives the loss probability and the mean waiting time by Little's law. We also give a simple numerical examples to apply the overload control in packetized networks.

• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.39 no.3
• /
• pp.147-155
• /
• 2016

Industry 4.0's goal is the 'Smart Factory' that integrates and controls production process, procurement, distribution and service based on the fundamental technology such as internet of the things, cyber physical system, sensor, etc. Basic requirement for successful promotion of this Industry 4.0 is the large supply of semiconductor. However, company I who produces dicing blades has difficulty to meet the increasing demand and has hard time to increase revenue because its raw material includes high price diamond, and requires very complex and sensitive process for production. Therefore, this study is focused on understanding the problems and presenting optimal plan to increase productivity of dicing blade manufacturing processes. We carried out a study as follows to accomplish the above purposes. First, previous researches were investigated. Second, the bottlenecks in manufacturing processes were identified using simulation tool (Arena 14.3). Third, we calculate investment amount according to added equipments purchase and perform economic analysis according to cost and sales increase. Finally, we derive optimum plan for productivity improvement and analyze its expected effect. To summarize these results as follows : First, daily average blade production volume can be increased two times from 60 ea. to 120 ea. by performing mixing job in the day before. Second, work flow can be smoother due to reduced waiting time if more machines are added to improve setting process. It was found that average waiting time of 23 minutes can be reduced to around 9 minutes from current process. Third, it was found through simulation that the whole processing line can compose smoother production line by performing mixing process in advance, and add setting and sintering machines. In the course of this study, it was found that adding more machines to reduce waiting time is not the best alternative.

• Proceedings of the KSR Conference
• /
• 2011.10a
• /
• pp.2077-2081
• /
• 2011

Recently the train indusrty come to the fore because of Punctual, eco-friendly transportation system and becoming the main transportation. The construction plans for the trian depot for train's maintenance and storage increase constantly. For past few years, there were many construction plans, Bubal train depot, Gwangju train depot, Duckha train depot. Proper track distribution plan is important to carry out the design of railway depot for efficient maintenance operation and train storage. Through the proper design of track distribution plan, we can shorten the moving time, train movement distance, waiting time in train depot. In this paper, the verification of the track distribution plan's efficiency and appropriateness for railway depot as Bubal train depot's plan is studied and analyzed with the train depot management simulation program-Posrail(v1.0).

• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• 1998.10a
• /
• pp.323-329
• /
• 1998

In Pusan port, the studies, which analysis container cargo volumes by using forecasting methods and research about container logistics system, etc., have been continuously performed. But, in Pusan port, this study on an evaluation of traffic congestion has been scarcely performed until now. Especially, when changing and extending a berth, and constructing a new port, it is very important to examine this field. And it should be considered. Thus, this paper aims to analysis the effect of ship traffic condition in 2011, to evaluate marine traffic congestion, according to changing ship traffic volumes in Pusan port. To analysis it, we used simulation method and examined the results

• Journal of KIISE:Computing Practices and Letters
• /
• v.12 no.2
• /
• pp.111-118
• /
• 2006

In this thesis, we analyze the efficiency of the algorithm to distribute the load in the clustered system, by comparing with the existed algorithm. PWLC algorithm detects each server's load in the system at weighted period, and following the detection of the loads, a set of weights is given to each server. The system allocates new loads to each server according to its weight. PWLC algorithm is compared with DWRR algorithm in terms of variance, waiting time by varying weighted Period. When the weighted period is too short, the system bears a heavy load for detecting load over time. On the other hand, when the weighted period is too long, the load balancing control of the system becomes ineffective. The analysis shows PWLC algorithm is more efficient than DWRR algorithm for the variance and waiting time.

• Journal of the Korean Institute of Rural Architecture
• /
• v.12 no.4
• /
• pp.29-36
• /
• 2010

The purpose of this study is to have detailed data of the distribution, locations, and the amount of people in the waiting line of the nursing home. Also, we studied the accessibility to the facilities by using Web GIS to analyze the transit time it takes from the nursing home to health center and hospitals. We can provide the basic data that could contribute when future plans for the nursing homes' locations, health and medical policy are made. The results are as follows. 1. The nursing homes are stiffly concentrated in regions of Seoul and Gyeongi-do where large number of the elderly covered by long-term care insurance and the waiting line was very long for the elderlies to enter the nursing homes. In these cities of Ulsan and Jeju where number of the elderly covered by long-term care insurance is relatively small, there were less facilities. 2. The nursing homes located in urban areas had higher occupancy rate and higher number of people in the waiting line. 3. The average time taken by driving from the nursing homes and health center was 10 minutes and there was not a noticeable difference between the cities. Driving from the nursing homes to hospitals in rural areas took 22 minutes which is 2.5 times of the time taken for urban areas. Daegu-si and Incheon-si had relatively short distance from the nursing homes and the hospitals while Jeju-do had the furthest. For rural areas, it is needed for health center to be equipped with a wider medical coverage, have closely connected with hospitals to minimize the differences they have from ones in rural areas. It is also needed to have ambulances equipped for tele-medical examination and treatment system.