• Korean Journal of Mathematics
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• v.29 no.2
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• pp.371-386
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• 2021

This paper investigates two discrete time queueing inventory models with positive service time and lead time. Customers arrive according to a Bernoulli process and service time and lead time follow geometric distributions. The first model under discussion based on replenishment of order upto S policy where as the second model is based on order placement by a fixed quantity Q, where Q = S - s, whenever the inventory level falls to s. We analyse this queueing systems using the matrix geometric method and derive an explicit expression for the stability condition. We obtain the steady-state behaviour of these systems and several system performance measures. The influence of various parameters on the systems performance measures and comparison on the cost analysis are also discussed through numerical example.

• Journal of the Korean Operations Research and Management Science Society
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• v.19 no.3
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• pp.235-241
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• 1994

We consider a B/G/1 queueing with vacations, where the server closes the gate when it begins a vacation. In this system, customers arrive according to a Bernoulli process. The service time and the vacation time follow discrete distributions. We obtain the distribution of the number of customers at a random point in time, and in turn, the distribution of the residence time (queueing time + service time) for a customer. It is observed that solutions for our discret time B/G/1 gated vacation model are analogous to those for the continuous time M/G/1 gated vacation model.

• Korean Journal of Veterinary Service
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• v.32 no.3
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• pp.287-292
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• 2009

This study was conducted to analyse risk factors which can influence on blood splash in slaughtered cattle in D slaughterhouse located in Gyeonggi province in 2008. A total of 13,056 cattle were studied by several risk factors such as species, gender, body weight, meat grade, weather (temperature), transport distance, lairaging time, moving time, mixing cattle from different sources. As the result of analysis, the total mean of blood splash was 0.70% and the rate was highest (0.94%) in castrated Hanwoo. The heavier body weight, the higher blood splash rate. The farms which have had more than one experience of blood splash tend to have high grade in meat quality. As a weather factor, the rate in summer season was lower than in winter season. It increased as transport distance getting longer and decreased when the lairaging time was 2~5 hours. We could know many risk factors strongly related with the occurrence of blood splash from this study.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.6
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• pp.2050-2077
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• 2015

One of the major issues in emerging cloud management system needs the efficient service level agreement negotiation framework, with an optimal negotiation strategy. Most researchers focus mainly on the atomic service negotiation model, with the assistance of the Agent Controller in the broker part to reduce the total negotiation time, and communication overhead to some extent. This research focuses mainly on composite service negotiation, to further minimize both the total negotiation time and communication overhead through the pre-request optimization of broker strategy. The main objective of this research work is to introduce an Automated Dynamic Service Level Agreement Negotiation Framework (ADSLANF), which consists of an Intelligent Third-party Broker for composite service negotiation between the consumer and the service provider. A broker consists of an Intelligent Third-party Broker Agent, Agent Controller and Additional Agent Controller for managing and controlling its negotiation strategy. The Intelligent third-party broker agent manages the composite service by assigning its atomic services to multiple Agent Controllers. Using the Additional Agent Controllers, the Agent Controllers manage the concurrent negotiation with multiple service providers. In this process, the total negotiation time value is reduced partially. Further, the negotiation strategy is optimized in two stages, viz., Classified Similarity Matching (CSM) approach, and the Truncated Negotiation Group Gale Shapely Stable Matching (TNGGSSM) approach, to minimize the communication overhead.

• Journal of the Korean Institute of Educational Facilities
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• v.24 no.6
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• pp.27-36
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• 2017

Educational facilities have an affect to make a decently learning environment. After constructed, it needs a maintenance plan to keep the performance or function which provide the repair time, repair scope and ratio. But the fundamental data are so insufficient that the field worker can't provide the maintenance plan and has no choice use the other data which concerned with apartment or office building. Above all, the service life is indispensible to make a repair plan because the repair time and scope would be provided within the service life. This study aimed at providing the method to make a service life of component in educational facilities and applying the method into the roof proof and floor finishing. Results are shown that first, it is important to set the $1^{st}$ repair time after constructed. when it proposes the three ways with the probability approach, choice probability model and cumulative cost function. Second, the service life of roof proof is provided with about 35 years. In addition, the service life of the floor finishing is about 40 years. These result would be utilized to conduct the repair plan under the service life.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.18 no.3
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• pp.551-569
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• 2024

With the rapid development of electric vehicles (EVs) industry, EV charging service becomes more and more important. Especially, in the case of suddenly drop of air temperature or open holidays that large-scale EVs seeking for charging devices (CDs) in a short time. In such scenario, inefficient EV charging scheduling algorithm might lead to a bad service quality, for example, long queueing times for EVs and unreasonable idling time for charging devices. To deal with this issue, this paper propose a Deep-Q-Network (DQN) based two-stage scheduling method for the large-scale EVs charging service. Fine-grained states with two delicate neural networks are proposed to optimize the sequencing of EVs and charging station (CS) arrangement. Two efficient algorithms are presented to obtain the optimal EVs charging scheduling scheme for large-scale EVs charging demand. Three case studies show the superiority of our proposal, in terms of a high service quality (minimized average queuing time of EVs and maximized charging performance at both EV and CS sides) and achieve greater scheduling efficiency. The code and data are available at THE CODE AND DATA.

• Korean journal of food and cookery science
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• v.26 no.6
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• pp.781-790
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• 2010

The purpose of this study was to analyze the levels of food sanitation knowledge and performance by school food service workers. The data were collected by 440 food service workers in Gyeongbuk province. The collected data were analyzed using the SAS package program (version 8.2 for Window). The results of this study are summarized as follows: 28.6% of the respondents worked in food service at the school where their children attended, 93.6% of the food service workers were part-time employees, and 40.4% had obtained cooking certificates. The food sanitation knowledge scores of food service workers differed significantly according to age (p<0.05), holding of cooking certificates (p<0.01), number of certificates (p<0.01), and whether food service workers is students' parents or not (p<0.01). In addition, the sanitation-performance-degree levels of a few sanitation management items were significantly different according to their food sanitation knowledge level, working time, and whether food service workers is students' parents or not. In conclusion, these factors that improve food service sanitation should be fully considered when food service workers are hired or when food service management policies are established. Additionally, sanitation education and training for school food service workers should be offered regularly with effective education media.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2004.04a
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• pp.43-48
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• 2004

RTP that is proposed supplement of real-time services on internet environment, as Real-time Transport Protocol, is the protocol that for the purpose of sending data of stream type. RTP and RTCP(Real-time Transport Control Protocol) basically work at the same time, RTCP serves with state information of network at present. RTP has important properties of a transport protocol that runs on end-to-end systems and provides demultiplexing. It also offer reliability and protocol-defined flow／congestion control that transport protocol like TCP can not provides. In this paper, we look around concept and construction of Differentiated sen1ice tint run on RTP and by setting parameters of packet transfer method be used CBQ(Class-Based Queuing) for packet transfer on Differentiated service, each service queue controls properly through packet scheduling method, such as WRR(Weighted Round Robin) and PRR(Packet-by-packet Round Robin) all service classes do not experience the starvation and confirm the performance through computer simulation to achieve fairly scheduling.

• Journal of the Korean Society for Railway
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• v.15 no.1
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• pp.88-95
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• 2012

Presently, because making process of train service plan consist of various constraint condition, for example structure of track, structure of track in station, train maintenance time and others for considering to be necessary of train management, it has been had extremely complex structure problems. For these reasons, it has big problems to compare analysis for various train service time-table. A study suggest methodology to choice service the most effective schedule and plan of train put before comparative analysis on making train diamond picture's expected effect of established possible various train time-table in making process of train service schedule for improving effectiveness and organization of train service schedule establishment. A study uses Line-Blocking theory for analyzing train service time-table and analyze example for regional train Sadang to Ansan section in 4line.

• Communications for Statistical Applications and Methods
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• v.19 no.1
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• pp.169-175
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• 2012

The sensitivity of the performance measures such as the mean and the standard deviation of the queue length and the blocking probability with respect to the moments of the service time are numerically investigated. The service time distribution is fitted with phase type(PH) distribution by matching the first three moments of service time and the M/G/c retrial queue is approximated by the M/PH/c retrial queue. Approximations are compared with the simulation results.