• The Transactions of the Korean Institute of Electrical Engineers P
• /
• v.60 no.3
• /
• pp.155-160
• /
• 2011

IPTV functions not only as media player that does play the broadcasting industry's contents, also as the gateway is guaranteed of QoS(Quality of Service). This is for free contents-sharing that device stores contents using home network circumstance, and is for watching with seamless network service. Also this have required next QoS model that can handle stably as it may contain more data of the small computing device in next generation home system. We need ubiquitous-oriented QoS's design and development project that focuses on internal and external media service, not the existing QoS nor one-sided QoS of media sevice industry. This paper focuses on network module development. This supports IPTV in media industry and two-way capability of QoS highlighting multimedia service in network industry. In additional, this can handle stably the multiplex signal of USN/RFID as the representative ubiquitous and home network that services high-speed wire and wireless interface, and support the seamless u-QoS.

• IE interfaces
• /
• v.25 no.3
• /
• pp.327-337
• /
• 2012

The development of information and communication technology affects people's life in social, cultural, and economic aspects. When this happens in public sector, it gives way more benefits than in private sector because of its high accessibility by public. Among the technological public services in Korea, call center service which provides administrative services by telephone and internet had been spotlighted as a new type of communication between people in demand and public service provider. Public call center service is expected to be continuously diffused in years due to its accessibility and convenience for public users. This study analyzes diffusion pattern of public call center service in Korea using Bass model and tries to suggest appropriate diffusion strategies. For practical cases, three most popular public call centers in Korea are analyzed in light of diffusion pattern and operating strategies. Our analyses identify that public call centers in Korea are facing continuous diffusion in two years and there exist certain strategies to efficiently expedite the diffusion.

• Journal of Applied Tourism Food and Beverage Management and Research
• /
• v.10
• /
• pp.159-186
• /
• 1999

This study attempted to present the ways of improving relationship marketing activities of tourist hotels. The field survey was carried out at six deluxe hotels in Seoul to find out their relationship marketing activities and analyze the problems of the activities. The problems were analyzed as follow; 1) lack of adequate understanding of the importance of relationship marketing, 2) poor contents of customer file information, 3) insufficient service encounter management, 4) negative inducement of guests' complaints, 5) insufficient survey of guests' satisfaction, 6) insufficient relationship maintenance programs and regaining program of lost guests. This study relationship marketing activities should be improved with customer information file establishment, service encounter mangement, and communication enforcement as follow; 1. Customer Information File Establishment As relationship marketing Is marketing for individual, it needs customer file information. The guest information files should be made in detail in all the market segments. Hotels have to make use of the information strategically for establishing relationship with their guests. 2. Service Encounter Mnagement Because the guest-oriented mind and professionalism of hotel staff are prerequisite for relationship continuity, hotel should make efforts to make its staff keep the mind and cultivate expert service technique of the staff. 3. Communication Enforcement Communication enforcement consists of communication activities and communication programs which are focused on contact intensity and two-way communication.

• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.39 no.2
• /
• pp.1-10
• /
• 2016

In this paper, we present a new way to derive the mean cycle time of the G/G/m failure prone queue when the loading of the system approaches to zero. The loading is the relative ratio of the arrival rate to the service rate multiplied by the number of servers. The system with low loading means the busy fraction of the system is low. The queueing system with low loading can be found in the semiconductor manufacturing process. Cluster tools in semiconductor manufacturing need a setup whenever the types of two successive lots are different. To setup a cluster tool, all wafers of preceding lot should be removed. Then, the waiting time of the next lot is zero excluding the setup time. This kind of situation can be regarded as the system with low loading. By employing absorbing Markov chain model and renewal theory, we propose a new way to derive the exact mean cycle time. In addition, using the proposed method, we present the cycle times of other types of queueing systems. For a queueing model with phase type service time distribution, we can obtain a two dimensional Markov chain model, which leads us to calculate the exact cycle time. The results also can be applied to a queueing model with batch arrivals. Our results can be employed to test the accuracy of existing or newly developed approximation methods. Furthermore, we provide intuitive interpretations to the results regarding the expected waiting time. The intuitive interpretations can be used to understand logically the characteristics of systems with low loading.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.15 no.1
• /
• pp.141-146
• /
• 2011

The GIS service has to provide latest spatio-temporal data for the effective service. The two-way synchronization scheme collects updated spatio-temporal data in the field and synchronizes with a server by using the wireless network. However, since the two-way synchronization scheme processes sequentially synchronizing work of clients, it has the problem that the synchronization of multiple clients takes long time. In this paper, we propose the concurrent synchronizations scheme based on the multi-queue in order to reduce the waiting time of multiple clients. We also build both schemes and evaulate the performance test. The results show that the proposed scheme reduce the waiting time by 31%.

• Journal of Broadcast Engineering
• /
• v.2 no.2
• /
• pp.182-193
• /
• 1997

In this paper, we propose technical and structural solutions for various problems in two-way digital communication services in CATV networks by actual field tests. The two-way digital communication services include VOD, video conferencing, distance learning, interactive game and internet service. We investigate the quality of T -1 level 0.544 Mbps) upstream digital signal while varying the number of subscribers in three different cells in accordance with ITU-T G.821. Based on this investigation, several ways to cope with the problems identified are suggested.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.11 no.12
• /
• pp.1175-1186
• /
• 2016

The relative distance estimation technique is important to Location-Based Service(: LBS) in a wireless communication environment. In this paper, we propose a scheme for measuring the relative distance by utilizing a frame structure of a physical layer in asynchronous Frequency Division Duplexing(: FDD) when the Internal and external infrastructure for position measurement cannot be used. The proposed method is suitable for continuous distance measurement. The test results showed that the proposed method has the accuracy of less than 10 meters on average.

• Proceedings of the KOR-KST Conference
• /
• 1996.02a
• /
• pp.59-86
• /
• 1996

Current methods for evaluating unsignalized intersections, and estimating level-of-service (LOS) is determined from efficiency-based criteria such as little or no delay to very long delays. At present, similar procedures to evaluate intersections using safety-based criteria do not exist. The improvement of sight distances at intersections is the most effective way of improving intersection safety. However, a set of procedures is necessary to account for the limitations in current methodology. Such an approach would build upon such methods, but also account for: deficiencies in the current deterministic solution for the determination of intersection sight distances; opportunity for an accident and severity of an accident; and cost-effectiveness of attaining various levels of sight distances. In this research, a model that estimates the degree of safety at two-way stop-controlled intersections is described. Only crossing maneuvers are considered in this study because accidents caused by the crossing maneuvers are the dominate type among intersection accidents. Monte Carlo methods are used to estimate the hazard at an intersection as a function of roadway features and traffic conditions. Driver`s minimum gap acceptance in the crossing vehicles and headway distribution on the major road are used in the crossing vehicles and headway distribution on the major road are used in the model to simulate the real intersectional maneuvers. Other random variables addressed in the model are: traffic speeds; preception-reaction times of both drivers in the crossing vehicles and drivers in oncoming vehicles on the major road; and vehicles on the major roads. The developed model produces the total number of conflicts per year per vehicle and total potential kinetic energy per year per vehicle dissipated during conflicts as measurements of safety at intersections. Based on the results from the developed simulation model, desirable sight distances for various speeds were determined as 350 feet, 450 feet and 550 feet for 40 mph, 50 mph and 60 mph prevailing speed on the major road, respectively. These values are seven to eight percent less than those values recommended by AASHTO. A safety based level-of-service (LOS) is also developed using the results of the simulation model. When the total number of conflicts per vehicle is less than 0.05 at an intersection, the LOS of the intersection is `A' and when the total number of conflicts per vehicle is larger than 0.25 at an intersection, the LOS is `F'. Similarly, when the total hazard per vehicle is less than 350, 000 1b-ft2/sec2, the LOS is `F'. Once evaluation of the current safety at the intersection is complete, a sensitivity analysis can be done by changing one or more input parameters. This will estimate the benefit in terms of time and budget of hazard reduction based upon improving geometric and traffic characteristics at the intersection. This method will also enable traffic engineers in local governments to generate a priority list of intersection improvement projects.

• Journal of Korean Society of Transportation
• /
• v.24 no.6 s.92
• /
• pp.55-64
• /
• 2006

Pedestrians and vehicle users ate competing for limited space in urban streets. Therefore, strategical planning and design should be considered to balance the needs placed on urban streets. The study suggested a way to put this concept in to practice by comparing level of service(LOS) of pedestrians and vehicles in the planning and design stage. Also. the study considered the priority among two users basing on the land use characteristics and the functional hierarchy of the streets. In order to overcome the lack or prediction or survey of pedestrian demands in design process, new pedestrian LOS applicable to sidewalk design was suggested based on the comfort linked with the physical limitation. The comparison of the suggested way and the existing way provided at the end of the paper.

• Korean Management Science Review
• /
• v.9 no.1
• /
• pp.3-15
• /
• 1992

In this paper, we study a manufacturing system of serial stages with general service times, in which the production of each stage and the coordination of stages are controlled by Kanban discipline. This Kanban discipline is modeled as a Discrete Event Dynamic System and a system of recursive equations is applied to study the dynamics of the system. The recursive relationship enables us to compare this Kanban discipline with the other blocking disciplines such as transfer blocking, service blocking, block-and-hold b, and block-and-hold K, and the Kanban is shown to be superior to the other disciplines in terms of makespan and throughput. As a special case, two stages Kanban system is modeled as $C_2/C_2/1/N$ queueing system, and a recursive algorithm is developed to calculate the system performance. In optimizing the system performance, the stochastic optimization approach of Robbins-Monro is employed via perturbation analysis, the way to estimate the stochastic partial derivative based on only one sample trajectory of the system, and the required commuting condition is verified. Then the stochastic convexity result is established to provide second-order optimality condition for this parametric optimization problem.