• Proceedings of the Korean Operations and Management Science Society Conference
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• 2006.05a
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• pp.1093-1100
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• 2006

본 연구는 D-정책을 갖는 BMAP/G/1 대기행렬 시스템의 일량(workload) 및 대기시간(waiting time)을 분석한다. 유휴한 서버는 도착하는 고객들의 서비스 시간의 총합이 주어진 임계점 D를 넘어야만 서비스를 시작한다. 고객의 도착과정은 집단마코비안도착과정(BMAP, Batch Markovian Arrival Process)을 따른다. 본 논문에서는 이러한 시스템의 일량 및 대기시간에 대한 LST를 구하고, 이로부터 평균일량 및 평균대기시간을 유도한다. 또한 BMAP/G/1의 특별한 경우인 $M^X/G/1$인 경우와 대기시간의 비교를 행한다.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2002.05a
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• pp.841-844
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• 2002

Recently there has been an increasing interest in queueing models with disasters. Upon arrival of a disaster, all the customers present are noshed out. Queueing models with disasters have been applied to the problems of failure recovery in many computer networks systems, database systems and telecommunication networks in this paper, we suffest the steady state and sojourn time distributions of the M/G/l model with disaster and mass alway when the system is empty.

• Journal of the Korean Operations Research and Management Science Society
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• v.25 no.1
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• pp.15-26
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• 2000

We consider an open tandem queueing network with population constraint and constant service times. The total number of customers that may be present in the network can not exceed a given value k. Customers arriving at the queueing network when there are more than k customers are forced to walt in an external queue. The arrival process to the queueing network is assumed to be arbitrary. It is known that the queueing network with population constrant and constant service times can be transformed into a simple network involving only two nodes. In this paper, the departure process from the queueing network is examined using this simple network. An approximation can be calculated with accuracy. Finally, validations against simulation data establish the tightness of these.

• Journal of the Korean Operations Research and Management Science Society
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• v.32 no.3
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• pp.17-31
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• 2007

In this paper, we consider a service system with bi-functional servers, which can switch between the primary service room and the secondary room. A service policy is characterized by the switching paints which depend on the queue length in the primary service room and the service level requirement constraint of the secondary room. The primary service room is modeled as a Markovian queueing system and the throughput of the primary service room is function of the total number of bi-functional servers. the buffer capacity of the primary service room, and the service policy. There is a revenue obtained from throughput and costs due to servers and buffers. We study the problem of simuitaneously determining the optimal number of servers, buffer capacity, and service policy to maximize profit of the service system, and develop an algorithm which can be successfully applied with the small number of computations.

• Journal of the Korea Safety Management & Science
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• v.9 no.5
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• pp.57-66
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• 2007

본 논문에서는 통신망의 트래픽 제어를 위한 무한버퍼, 단일 서버와 배치도착과정을 갖는 대기행렬 모형을 고려하였다. 또한 고객 도착 형태와 서비스의 분포는 지수분포를 배치 흐름은 포아송 정상과정 및 배치크기는 기하분포를 따른다고 가정하였다. 서비스를 받기 위해 시스템으로 들어오는 배치의 크기는 시스템의 상태에 따라서 트래픽 제어가 가능하다. 이와 같은 조건에서 시스템에 있는 고객의 수와 배치크기에 대한 결합 확률분포를 분석하였고, 행렬기법을 적용하여 시스템 체재시간에 대한 분석이 수행되었다. 마지막으로 시스템의 주요 성능평가 척도에 대한 효율적인 제어기법에 대한 언급과 수치예제를 통해서 증명하였다.

• Journal of Korean Institute of Industrial Engineers
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• v.40 no.1
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• pp.135-139
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• 2014

In a connection-oriented packet switching network, the data communication starts after a virtual circuit is established between source and destination. The virtual circuit establishment time includes the queue waiting times in the direction from source to destination and the other way around. We use this two-way queueing delay to evaluate scheduling policies of a packet switching processor through simulation studies. In this letter, we also suggest user testing functions for the packet switching processor to manage virtual circuits. By detecting error causes, the user testing helps the packet switching processor provide reliable connection-oriented services.

• Journal of Korea Society of Digital Industry and Information Management
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• v.17 no.3
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• pp.9-15
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• 2021

In this paper, the Embedded MEMS system to the power apparatus used Edge Impulse machine learning tools and therefore an improved predictive system design is implemented. The proposed MEMS embedded system is developed based on nRF52840 system and the sensor with 3-Axis Digital Magnetometer, I2C interface and magnetic measurable range ±120 uT, BM1422AGMV which incorporates magneto impedance elements to detect magnetic field and the ARM M4 32-bit processor controller circuit in a small package. The MEMS embedded platform is consisted with Edge Impulse Machine Learning and system driver implementation between hardware and software drivers using SensorQ which is special queue including user application temporary sensor data. In this paper by experimenting, TensorFlow machine learning training output is applied to the power apparatus for analyzing the status such as "Normal, Warning, Hazard" and predicting the performance at level of 99.6% accuracy and 0.01 loss.

• 한국항공운항학회:학술대회논문집
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• 2016.05a
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• pp.269-275
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• 2016

This paper considers the arrival, airport and departure capacity as a whole, through which, the network effect between airports is fully emphasized, the flight action is coordinated, and the flight demand pattern is reasonably assigned. The optimization problem of flight queues in multi-airport is studied in detail; the mathematical model of multi-airport opening non-real time flow management in terminal area is established, and related problems such as the parameters, the simplification and the solving of the model are discussed in detail to some extent. Appropriate decision making variables are taken to make the multi-airport network system linear 0-1 integer programming model, thus, the solving of the model is available and the central flow management is realized. The heuristic implicit enumeration presented in this paper can effectively solve this kind of problems. Through the simulation of some airports network system, we not only validate the algorithm presented in this paper, but also give a deep analysis of the results, which would produce reference for later practicable use. The simulation proves that this algorithm offers a good way to settle the problem of multi-airport flight queue optimization in air traffic management automation system in terminal area.

• Journal of the Institute of Electronics and Information Engineers
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• v.49 no.11
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• pp.205-210
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• 2012

This paper investigated the performance of QoS management using variations of RED parameters in Differentiated Service. Differentiated Service separates packets from a specific traffic by using QoS parameters such as CIR or PIR. A code point is used to mark each packet which is enqueued into each virtual queue. Different RED parameters are configured for virtual queues according to each code point. As the code point value increases, the RED parameters become harsher. To show QoS Management using variations of RED parameters, this paper used the policy model of time sliding window with 2 color marking (TSW2CM). Simulation results using NS-2 showed that the QoS management of a differentiated service can be obtained from using variations of RED parameters.

• 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.