• Journal of the Korean Professional Engineers Association
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• v.28 no.3
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• pp.121-134
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• 1995

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 unit con-trol devices located In common manufacturing zone and operated by connecting them. The network management system, which controls and supervises the network resources in the communication network, is the function that is necessarily required in this net-work. 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 token rotation time and waiting time for the network operation. On the evalution of the performance, the data packet length varies from 10 bytes to 100 bytes in the operation of the group manage-ment network, the variation of the token rotation time and waiting time is less than 10 msec. When the variation of the data packet lenhth is less than 50 bytes, differences in token rotation time or waiting time is unnoticable. Since the waiting time in this case is less than 10 msec, response time Is fast enough.

• The Transactions of the Korea Information Processing Society
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• v.7 no.2S
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• pp.649-655
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• 2000

Real-time application programs have constraints which need to be met between media-data. These constraints represents the delay time ad quality of service between media-data to be presented. In order to efficiently describe the delay time and quality of service, a new synchronization mechanism is needed. Proposed paper is a dynamic synchronization that minimized the effects of adaptive transmission delay time. That is, the method meets the requirements of synchronization between media-dat by handling dynamically the adaptive waiting time resulted from variations of delay time. In addition, the mechanism has interval adjustment using maximum delay jitter time. This paper decreases the data loss resulted from variation of delay time and from loss time of media-data by means of applying delay jitter in order to deal with synchronization interval adjustment. Plus, the mechanism adaptively manages the waiting time of smoothing buffer, which leads to minimize the gap from the variation of delay time. The proposed paper is suitable to the system which requires the guarantee of high quality of service and mechanism improves quality of services such as decrease of loss rate, increase of playout rate.

• Journal of applied mathematics & informatics
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• v.42 no.3
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• pp.709-723
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• 2024

We study the distributions of waiting times in variations of the geometric distribution of order k. Variation imposes length on the runs of successes and failures. We study two types of waiting time random variables. First, we consider the waiting time for a run of k consecutive successes the first time no sequence of consecutive k failures occurs prior, denoted by T^(k). Next, we consider the waiting time for a run of k consecutive failures the first time no sequence of k consecutive successes occurred prior, denoted by J^(k). In addition, we study the distribution of the weighted average. The exact formulae of the probability mass function, mean, and variance of distributions are also obtained.

• The Transactions of the Korea Information Processing Society
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• v.4 no.11
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• pp.2801-2811
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• 1997

This thesis Proposes a media synchronization mechanism for video conferencing system by analyzing a variation of the delay time of media. Using this mechanism, this thesis analyzes the media traffics and determines the values of external variables important on waiting time. This system uses some dummy streams to get the time. When two hosts are initially connected, they change the dummy streams by which a logical time of the sender may be extracted. The time presenting a media stream is a sum of base time, logical time and the waiting time. At this time, for the purpose of optimally adjusting the waiting time, this mechanism uses the rate of updating the waiting time and the sampling unit of media. These values are acquired by analyzing the waiting times, the delay rates and the delayed arrival times.

• The Journal of Society for e-Business Studies
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• v.4 no.1
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• pp.87-101
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• 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 Korea Society for Simulation
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• v.8 no.4
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• pp.73-87
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• 1999

Order Review/Release (ORR) System is the linkage between planning system and actual production. Reduction of the waiting time on the machines, work in process and lead time variation may be achieved by adopting ORR strategies. But researchers on the ORR do not agree on the effectiveness of ORR. Some say that the overall system flow time may be increased if ORR is adopted, but others say that ORR can reduce work in process, flow time and variation of flow time. The objective of this research is to clarify under what environments order release strategy is effective. Simulation study was conducted in a hypothetical job shop. The experimental results show that dispatching rule is much more important than ORR is in controlling the shop floor. But the results indicate that ORR can reduce mean shop flow time, average work in process and variation of shop flow time under such environments where utilization level is high and planned order is weekly released to the order pool. And the results also show that the effect of plan smoothing on the ORR is insignificant, which is inconsistent with the results of the previous researches.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.34 no.5
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• pp.1525-1534
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• 2014

In recent years, the passengers are likely to decide their route on impulse due to the development of the integrated public transport system, and real-time information system. Especially, public transport fare integration in Seoul Metropolitan area, 2004 makes them not to have resistance about changing the modes or routes and their route choice is most effected by the degree of congestion. Assignment model have limitations to describe route changes by congestion. In this study, the concept of a link cost function used in road assignment and Effective frequency is introduced to describe the passengers' behavior when the capacity of public transport is over and the waiting time variation. Two situations, new transit line operation and accident, are set up to validate the model, as a result of the transit assignment by this model, the traffic on networks is not over the capacity. It is expected that this study will be of help to reflect the various behaviors in transit assignments.

• Korean Management Science Review
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• v.19 no.1
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• pp.1-12
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• 2002

Performances of common zone with various sizes are examined for possible demand rate variations for an AS/RS. Common zone is a middle area located between the 1st class and the 2nd class to be used by the 1st class Items if the assigned racks are not enough. This area is designed to resolve the rack shortage problem associated with a particular class. In the previous researches, effect of demand rate variation is Ignored since flxed demand rate is assumed. It is found that rack shortage rate is decreased up to 67% of common zone size. However, no difference is found at above 70%. Waiting time tends to be longer with Increased common zone while travel time and throughput are not affected at all with the common zone sloe.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.18 no.1
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• pp.110-122
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• 1993

When voice is transmitted through packet switching network, there needs a overload control, that is, a control for the congestion which lasts short periods and occurrs in local extents. In this thesis, we analyzed the performance of the statistical packet voice multiplexer using the overload control strategy by bit dropping. We assume that the voice is coded accordng to (4,2) embedded ADPCM and that the voice packet is generated and transmitted according to the procedures in the CCITT recomendation G. 764. For the performance analysis, we must model the superposed packet arrival process to the multiplexer as exactly as possible. It is well known that interarrival times of the packets are highly correlated and for this reason MMPP is more suited for the modelling in the viewpoint of accuracy. Hence the packet arrival process in modeled as MMPP and the matrix geometric method is used for the performance analysis. Performance analysis is similar to the MMPP IG II queueing system. But the overload control makes the service time distribution G dependent on system status or queue length in the multiplexer. Through the performance analysis we derived the probability generating function for the queue length and using this we derived the mean and standard deviation of the queue length and waiting time. The numerical results are verified through the simulation and the results show that the values embedded in the departure times and that in the arbitrary times are almost the same. Results also show bit dropping reduces the mean and the variation of the queue length and those of the waiting time.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.11
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• pp.5512-5517
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• 2012

In this paper we suggest multimedia synchronization model that is based on the Petri-net and services desirable quality of service requirement. Proposed model applies variable buffer which can be allowed, and then it presents high quality of service and real time characteristics. This paper decreases the data loss resulted from variation of delay time and from loss time of media-data by means of applying delay jitter in order to deal with synchronization interval adjustment. Plus, the mechanism adaptively manages the waiting time of smoothing buffer, which leads to minimize the gap from the variation of delay time. The proposed paper is suitable to the system which requires the guarantee of high quality of service and mechanism improves quality of services such as decrease of loss rate, increase of playout rate.