• Journal of the Korean Operations Research and Management Science Society
• /
• v.24 no.2
• /
• pp.31-39
• /
• 1999

A new approximation method for finding the steady-state probabilities of the number of customers present in queueing systems with Poisson arrivals and two servers with different deterministic service times with infinite waiting room capacity is developed. The major assumption made for the approximation is that the residual service times of the servers have mutually independent uniform distributions with densities equal to the reciprocals of the respective service times. The method reflects the heterogeneity of the servers only through the ratio of their service times, irrespective of the actual magnitudes and difference. The transition probability matrix is established and the steady-state probabilities are found for a variety of traffic intensities and ratios of the two service times; also the mean number of customers present in the system and in the queue, and server utilizations are found and tabulated. The method was validated by simulation and turned out to be very sharp.

• Nutrition Research and Practice
• /
• v.15 no.sup1
• /
• pp.22-31
• /
• 2021

Coronavirus disease 2019 (COVID-19) is a new type of respiratory disease that has been announced as a pandemic. The COVID-19 outbreak has changed the way we live. It has also changed the food service industry. This study aimed to identify trends in the food and food service industry after the COVID-19 outbreak and suggest research themes induced by industry trends. This study investigated the industry and academic information on the food and food service industry and societal trends resulting from the COVID-19 outbreak. The most noticeable changes in the food industry include the explosive increase in home meal replacement, meal-kit consumption, online orders, take-out, and drive-through. The adoption of technologies, including robots and artificial intelligence, has also been noted. Such industry trends are discussed in this paper from a research perspective, including consumer, employee, and organizational strategy perspectives. This study reviews the changes in the food service industry after COVID-19 and the implications that these changes have rendered to academia. The paper concludes with future expectations that would come in the era of COVID-19.

• Journal of Korean Society for Quality Management
• /
• v.46 no.1
• /
• pp.135-152
• /
• 2018

Purpose: This study attempted to analyze how the ego state of flight attendants affects their job satisfaction and customer orientation using Berne's (1966) transactional analysis and further compare the difference between job satisfaction and customer orientation depending on demographic characteristics, position, and ego state. Methods: The data was collected by using the structured questionnaires to flight attendant of major airline companies. The proposed research model is tested using 164 valid questionnaires using SPSS 23 and Smart PLS 2. Results: This research indicated the only free child ego sate among ego state factors of flight attendant was found to have a positive impact on job satisfaction. In the relationship between ego states and customer orientation, all ego state factors were found to have a significant influence on customer orientation. Conclusions: The study offered a theoretical and empirical foundation for future research by empirically identifying the relationship between ego state factors and customer orientation in the in-flight service and suggested the strategic implications to increase job satisfaction and customer orientation based on the psychology and ego state of flight attendant.

• Journal of Communications and Networks
• /
• v.17 no.3
• /
• pp.306-320
• /
• 2015

Due to an explosive growth in services running in different datacenters, there is need for service selection and routing to deliver user requests to the best service instance. In current solutions, it is generally the client that must first select a datacenter to forward the request to before an internal load-balancer of the selected datacenter can select the optimal instance. An optimal selection requires knowledge of both network and server characteristics, making clients less suitable to make this decision. Information-Centric Networking (ICN) research solved a similar selection problem for static data retrieval by integrating content delivery as a native network feature. We address the selection problem for services by extending the ICN-principles for services. In this paper we present Queue and Latency, a network-driven service selection algorithm which maps user demand to service instances, taking into account both network and server metrics. To reduce the size of service router forwarding tables, we present a statistical method to approximate an optimal load distribution with minimized router state required. Simulation results show that our statistical routing approach approximates the average system response time of source-based routing with minimized state in forwarding tables.

• Proceedings of the IEEK Conference
• /
• 2002.07c
• /
• pp.1606-1609
• /
• 2002

MAC state models appeared with an effort to overcome technical demerits of CDMA in provisioning packet data service. In the scenario of sojourn and transition on MAC states, the design of state sojourn time is a critical issue for an efficient utilization of limited recource; a longer sojourn time leads to more resource being preserved for inactive stations, while more connection components should be recovered with a shorter sojourn time. Thus, the sojourn time at each MAC state must be optimized in consideration of these two conflicting arguments. In this paper, we first present a generic MAC state model. Secondly, based on the generic model, we reveal a relation of inactive period and the delay time of the last packet served in pre- ceding active period and specify a loss function reflect-ing two antinomic features that result from a change of state sojourn time. Using the proposed loss function, we construct a decision problem to find an optima3 rule for state sojourn times. Finally, we present a way of computing Bayes rule by use of the posterior distribution of inactivity duration for given observation on the delay time of last packet. Furthermore, Bayes rules are explicitly expressed for special arrival processes and investigated with respect to traffic load and loss parameters.

• Journal of KIISE:Information Networking
• /
• v.33 no.3
• /
• pp.247-256
• /
• 2006

Among the resource provisioning mechanisms for the hose based Virtual Private Network (VPN) Quality of Service (QoS ), VPN-specific state provisioning allows the service provider to obtain highest resource multiplexing gains. However, dynamic and automatic resource reservation for the VPN-specific state provisioning is difficult due to the lack of appropriate resource reservation protocol. Furthermore, users of a VPN may experience unfair usage of resources among themselves since the reserved resources of a VPN are shared by the VPN users in a similar way that the traditional LAN bandwidth is shared by the attached hosts. In this paper, we propose a resource reservation protocol and a traffic service mechanism, which not only enable dynamic and automatic resource reservation according to the VPN-specific state provisioning algorithm, but also enforce the fair usage of reserved resources among the users of a VPN in case of congestion.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.9 no.10
• /
• pp.3945-3964
• /
• 2015

Since the decentralized structure and the blindness of a large-scale wireless network make it difficult to collect the real-time channel state or other information from random distributed relays, a fundamental question is whether it is feasible to perform the relay selection without this knowledge. In this paper, a Slotted ALOHA based Greedy Relay Selection (SAGRS) scheme is presented. The proposed scheme allows the relays satisfying the user's minimum transmission request to compete for selection by randomly accessing the channel through the slotted ALOHA protocol without the need for the information collection procedure. Moreover, a greedy selection mechanism is introduced with which a user can wait for an even better relay when a suitable one is successfully stored. The optimal access probability of a relay is determined through the utilization of the available relay region, a geographical region consisting of all the relays that satisfy the minimum transmission demand of the user. The average number of the selection slots and the failure probability of the scheme are analyzed in this paper. By simulations, the validation and the effectiveness of the SAGRS scheme are confirmed. With a balance between the selection slots and the instantaneous rate of the selected relay, the proposed scheme outperforms other random access selection schemes.

• Korean Security Journal
• /
• no.8
• /
• pp.1-26
• /
• 2004

The current consitutional law 29-1 is ordaining the State Tort Liability for the illegal action of public service personnel. Based on this regulation, the State Tort Liability Act 2-1 actualizes by indicating, the nation or the local self-governing community is responsible for the public service personnels damaging others during their office hours whether it is accidental or intentional. However, the same law is considered to be inappropriate for the damage relief. In order to supplement this problem, through examinations at both theoretical and systematic levels of Prima facie as well as the objectification and standardization of the damages are required for the national compensation for the police action. According to the objectification and standardization of the damage theory, the faulty actions of the public service personnel are the defects occurred during the office hours. In the case of the police action that frequently uses infringement administration, invading the liberty and rights of the people, it is necessary to interpret faulty damages during the office duties more comprehensively so as to extend its scope of the ordinary public service personnel accidental illegality. In order to warrant effectiveness of the securing the rights, it is crucial to distinguish whether the faulty actions are accidental or intentional. When proven to be damages by illegal police action, the police personnel is responsible for the faults, called Prima facie, the nation is liable for the damage relief.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2019.05a
• /
• pp.186-189
• /
• 2019

The technique named CORD is an algorithm that optimizes resources of Data Service Platform(DSP) in real time, and it has been developed for enhancing operability of DSP of Korean e-Navigation Project performed by Hanwha Systems and Ministry of Oceans and Fisheries(MOF) since 2016. It plays a critical role to recognize the state of DSP in early time and handling problems immediately when it occurs logical, physical error in order to make DSP steady state condition, which has something in common with maximizing operability of DSP and seamless maritime service to various ships in the sea. Therefore, as developing a noble technique that makes DSP steady state by diagnosing resource and operation status of DSP as well as by reconfiguring service queue optimally in real time, DSP can have shorter response time and higher chance of providing proper maritime service to ships in voyage.

• International Journal of Computer Science & Network Security
• /
• v.22 no.9
• /
• pp.69-74
• /
• 2022

The main purpose of the study is to determine the features of state regulation of the hotel and restaurant business in the digital economy. Particularly relevant are the processes of digitalization of the service sector. Trade and transport companies, enterprises in the hotel and restaurant industry, catering got the opportunity to expand the target audience, improve the quality of service, develop at an accelerated pace, take into account that in the global digital economy, victory will go to those whose arsenal will involve a large number of high-quality digital platforms. As a result of the study, key aspects of state regulation of the hotel and restaurant business in the digital economy were identified.