• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.13 no.5
• /
• pp.2544-2557
• /
• 2019

Adaptive bitrate streaming is a crucial element in the implementation of high-quality streaming of media content over the Internet. Dynamic adaptive streaming over HTTP (MPEG-DASH) has lately emerged as the de facto solution for over-the-top (OTT) video streaming services. In this paper, we perform macro-level analysis on a real-world MPEG-DASH-based Internet live broadcasting service to gain insight into its behavior throughout the end-to-end service-provision chain, from broadcasters to viewers. Based on this analysis, we propose methods to improve the quality-of-experience (QoE) of MPEG-DASH-based services, particularly with regard to reducing broadcasting delays between recording and viewing of videos, as well as synchronizing client terminals.

• Journal of Korea Port Economic Association
• /
• v.24 no.2
• /
• pp.175-192
• /
• 2008

Today's individual firms no longer compete as solely autonomous entities, but rather as supply chain. As such the competitive position of a port is not only determined by its internal strengths but also it is also affected by its links in a global supply chin. In other words, port competitiveness is becoming increasingly dependent on external coordination and control of the whole supply chain. The main purpose of this paper is to examine how a port embeds itself into supply chain in order to strengthen its competitive position by focusing on Dubai port case. This paper found that Dubai port used three phases-insertion, integration and dominance-as a strategies for how it can embedded into global supply chain successfully. Dubai's global supply chain strategies give some implications for the further development of the Port of Gwangyang. First, the Port of Gwangyang should fully utilize symbiotic relationship with Gwangyang free Economic Zone. Second, the integration between Korea Container Terminal Authority and GYFEZ can be recommended for fast decision-making and providing a one-stop-service. Finally, Gwangyang should pursue an aggressive supply chain strategy, aims at dominance in the regional port network through port alliance with small and medium ports in neighboring area.

• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.39 no.4
• /
• pp.137-146
• /
• 2016

In recent years, business environment is faced with multi uncertainty that have not been suffered in the past. As supply chain is getting expanded and longer, the flow of information, material and production is also being complicated. It is well known that development service industry using application software has various uncertainty in random events such as supply and demand fluctuation of developer's capcity, project effective date after winning a contract, manpower cost (or revenue), subcontract cost (or purchase), and overrun due to developer's skill-level. This study intends to social contribution through attempts to optimize enterprise's goal by supply chain management platform to balance demand and supply and stochastic programming which is basically applied in order to solve uncertainty considering economical and operational risk at solution supplier. In Particular, this study emphasizes to determine allocation of internal and external manpower of developers using S&OP (Sales & Operations Planning) as monthly resource input has constraint on resource's capability that shared in industry or task. This study is to verify how Stochastic Programming such as Markowitz's MV (Mean Variance) model or 2-Stage Recourse Model is flexible and efficient than Deterministic Programming in software enterprise field by experiment with process and data from service industry which is manufacturing software and performing projects. In addition, this study is also to analysis how profit and labor input plan according to scope of uncertainty is changed based on Pareto Optimal, then lastly it is to enumerate limitation of the study extracted drawback which can be happened in real business environment and to contribute direction in future research considering another applicable methodology.

• The Journal of the Korea Contents Association
• /
• v.15 no.2
• /
• pp.433-443
• /
• 2015

This study aims to analyze key antecedents of customer loyalty based on dedication-based and constraint-based mechanisms. Our framework provides a theoretical lens of how two distinctive mechanisms influence customer loyalty in a coffee chain context. In this regard, this study examines the effects of customer satisfaction and switching costs on customer loyalty in a coffee shop market. In order to test the proposed model, data collected from 263 university students were empirically tested by using partial least squares regression. The analysis results reveal that customer loyalty is jointly influenced by both a dedication-based and a constraint-based mechanisms. Coffee quality service quality, price and value, and service atmosphere significantly affect user satisfaction. Habit and brand image were found to be the key factors of forming perceived switching costs.

• The Journal of The Korea Institute of Intelligent Transport Systems
• /
• v.11 no.4
• /
• pp.104-111
• /
• 2012

It is advantageous to avoid the handover to cell whose dwell time is short or can be ignored in terms of service continuity and average throughput. This paper proposes the handover scheme that is suitable for vehicle in order to improve the wireless Internet service quality. In the proposed scheme, the handover process continues to be learned before being modeled to Discrete-Time Markov Chain (DTMC). This modeling reduces the handover frequency by preventing the handover to cell that could provide service sufficiently to passenger even when vehicle passed through the cell but there was no need to perform handover. In order to verify the proposed scheme, we observed the average number of handovers, the average RSSI and the average throughput on various moving paths that vehicle moved in the given urban environment.

• Neonatal Medicine
• /
• v.25 no.4
• /
• pp.144-152
• /
• 2018

Purpose: The aim of this study was to investigate the clinical characteristics of Respiratory syncytial virus (RSV) infection during the neonatal period to provide information that is useful in clinical practice and suggest extension of the palivizumab administration. Methods: Neonates admitted to the National Health Insurance Service Ilsan Hospital neonatal intensive care unit due to respiratory symptoms and for whom multiplex reverse transcription-polymerase chain reaction and multiplex real time-polymerase chain reaction tests were performed between October 2011 and May 2016 were included in this study. Medical records were retrospectively reviewed, and data was collected for 156 neonates. Results: Among the 156 neonates, RSV was detected in 114 (73.1%), non-RSV in 25 (16%), and no virus in 17 (10.9%). The majority were full term infants (92.4%) and peak incidence of RSV infection was in January. Post-natal care center infection was more common in the RSV group (46.6%) than that in the other virus groups (24%, P=0.0243). Clinical symptoms were severe in the RSV group in contrast to that in the non-RSV or others groups. The RSV group frequently needed oxygen therapy (P=0.0001) and the duration of hospital stays were longer (P=0.0001). Conclusion: RSV is a significant cause of respiratory infection in neonates and the severity is higher in contrast to that with other viral causes of infection. Infants in post-natal care centers have a high-risk of developing RSV infections; therefore, palivizumab administration may be considered in this group to prevent hospitalization and reduce the duration of hospital stay.

• Proceedings of the Korean Operations and Management Science Society Conference
• /
• 2001.10a
• /
• pp.147-149
• /
• 2001

Customer centered supply chain Management is becoming a very important issue for manufacturing and distribution company. Increasingly, leading companies improve their competitiveness by shorting the time to delivery from warehousing to delivering, increasing the level of customer service. They also do their best to collaborate with suppliers and customers based on the information sharing. This case introduces a integrated approach to develop a logistics automation and information system for the spare parts distribution center of L electronics. We pursue to optimize the supply chain by implementing intelligent logistics system which has the capabilities of responding to the changes in market demands. This would provide many implications to the clients in solving logistics problems and secure superior competitiveness.

• Journal of applied mathematics & informatics
• /
• v.28 no.1_2
• /
• pp.153-162
• /
• 2010

The finite buffer GI/G/1/K system is set up by using an unconventional arrangement of the state space, in which the remaining interarrival time or service time is chosen as the level. The stationary distributions of resulting Markov chain can be explicitly determined, and the chain is positive recurrent without any restriction. This is an advantage of this method, compared with that using the elapsed time approach [2].

• Korean Management Science Review
• /
• v.27 no.3
• /
• pp.137-147
• /
• 2010

Real-time supply chain environments based on RFID will be an important topic in future society; Nevertheless, adopting RFID in real industry SCM is still in its infancy. The aim of this paper is to develop the physical framework of a fully adopting RFID system from manufacturing to recycle phase and measure the effect. So, we built a simulation station with fully appling RFID and analyzed benefits with mathematic model. Then, specifying the advantages and improvement scheme for real industry limitations were suggested. This work concluded that fully appling RFID in SCM gives improvement of quality and service to both production and consumer.

• Spatial Information Research
• /
• v.11 no.4
• /
• pp.439-452
• /
• 2003

Geographic Information System(GIS) market in Korea was made based on "the First Master Plan for the korean National GIS" Recently the private GIS market is growing rapidly for LBS, Telematics, Web Geographic Information Service. So, the purpose of this study is to make the development strategies reflected ′moving the core of GIS market′ from public to private sector. By using the Model of Added Value chain, the business model which reflect features of geographical information best, we analyzed markets and classified them into four fields along the uses and degrees of added value. The features of markets in each field are researched and the ways of development about each fields are established. And the business model for geoaphic information circulation is made for development of GIS. market. To realize the development strategies in each field, this study proposes the national roles.