• Journal of the Institute of Electronics Engineers of Korea TC
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• v.39 no.7
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• pp.1-11
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• 2002

This paper proposes that an efficient routing entry sending method between routing controller FE. based on this method, we organize IP VPN support method based on MPLS network and design MPLS-VPN service control module, MPLS-VPN processing, VPN group configuration and LSP setup processing. We evaluate the performance about the VPN based on proposed MPLS, at the result of evaluation. We figure out that based on proposed IPC method, lost packets number reduces and delay increases more slowly in case of VPN based on MPLS comparing with the VPN based on ATM which has rapid delay increasement. Therefore we confirm that the VPN based on MPLS has high speed of packet processing and high utilization of buffers through the performance evaluation.

• Journal of Satellite, Information and Communications
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• v.5 no.2
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• pp.57-63
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• 2010

Many efficient frequency sharing methods are issued in present because of increasing users with various wireless communication terminals. In the satellite communications, the service coverage is generally very wide so frequency sharing with terrestrial system is essentially needed, and the research is progressing dynamically related on this frequency sharing method. But if we adopt the terrestrial system which is commonly used, it can't avoid the interference from terrestrial service to satellite service. Therefore, this paper will introduce methods for reducing the interference from terrestrial station to earth station using cognitive radio system Satellite system is guaranteed with decreasing interference from terrestrial stations using Genetic Algorithm based power control method. Furthermore, terrestrial systems can have increased QoS because the frequency reuse factor in proposed method is higher than existing methods.

• Journal of KIISE
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• v.42 no.11
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• pp.1339-1348
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• 2015

In a distributed system environment based on a service-oriented architecture, separate systems collaborate to achieve the goals of the entire system by using services provided other systems. A service quality violation from using one service can cause runtime system failure in the environment. The existing self-adaptation methods follow fault tolerance mechanism that responds to a failure after a service quality violation. In other words, these methods are limited to responsive action. Therefore, a service-dependability-case based self-adaptation mechanism is necessary to preserve the dependability of the self-adaptive system. This paper demonstrates that the service-dependability-case based self-adaptation mechanism is better than QoS(quality of service)-based self-adaptation with fault tolerance to preserve the dependability of the self-adaptive system. Additionally, this paper suggests a method to present and analyze service dependability by using GSN(Goal Structuring Notation) which is the existing modeling method for the presentation of assurance cases, an action mechanism adapted using an analysis result of service-dependability-cases, a methods of leveraging the service-dependability-case based self-adaptation mechanism by following the service's life cycle, and the framework architecture including the major components and the interactions between the components in the control loop of the self-adaptation process.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.37 no.2
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• pp.24-31
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• 2000

The channel allocation strategy is very important in wireless multimedia networks since the mobility of users needs to be considered in addition to diversity of QoS requirements of multimedia traffic. A existing strategy to decrease the probability of handoff failure is guard channel method, which reserves channels at each base station for handoff calls. In this paper, we propose an efficient channel allocation strategy based on the prioritization of handoff calls used in the guard channel method. In the Proposed strategy guard channels are shared between non-real time and real time handoff calls. To decrease the probability of handoff failure, (when resources become scarce), the Call Admission Control takes some resources away from the active calls. The simulation results demonstrate that the Proposed strategy Provides higher channel utilization and lower probability of handoff failure than those of existing strategies.

• The KIPS Transactions:PartC
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• v.8C no.6
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• pp.805-814
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• 2001

In this paper, we propose a new scheduling algorithm that guarantees the delay property of real-time traffic, not considered in previous DWRR(Dynamic Weighted Round Robin) algorithm and also transmits non-real-time traffic efficiently. The proposed scheduling algorithm is a variation of DWRR algorithm to guarantee the delay property of real-time traffic by adding cell transmission method based on delay priority. It also uses the threshold to prevent the cell loss of non-real-time traffic due to cell transmission method based on delay priority. Proposed scheduling algorithm may increase some complexity over conventional DWRR scheme because of cell transmission method based on delay priority. However, the consideration of delay priority can minimize cell delay and require less size of temporary buffer. Also, the results of our performance study shows that the proposed scheduling algorithm has better performance than conventional DWRR scheme due to reliable ABR service and congestion avoidance capacity.

• The Journal of Internal Korean Medicine
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• v.40 no.3
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• pp.390-408
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• 2019

Objectives: Several pattern diagnosis questionnaires have been developed to objectify the process of pattern diagnosis in Korean medicine. In this context, this study aimed to develop a food retention questionnaire for functional dyspepsia (FRQ-FD) by modifying the previously developed food retention questionnaire (FRQ) and to verify its reliability and validity. Furthermore, this study aimed to identify the optimal cut-off value of the FRQ-FD for standardization and use in clinical situations. Methods: To develop the FRQ-FD, we extracted the major symptoms of food retention pattern for functional dyspepsia from Chinese/Korean medicine textbooks and requested an importance survey from experts using the Delphi method. The first draft of the FRQ-FD was composed of 25 questions comprising 8 questions from the textbooks and the Delphi method and 17 questions from the FRQ already developed in 2013. To analyze its reliability, validity, and optimal cut-off value, 60 subjects were enrolled in this study from June 25 to August 13, 2018. Thirty patients were diagnosed as both functional dyspepsia and food retention pattern, and 30 healthy participants were not. All participants were requested to fill up the FRQ-FD, Stomach Qi Deficiency Questionnaire (SQDQ), Scale for Stomach Qi Deficiency pattern (SSQD), visual analog scale (VAS) for dyspepsia, Nepean Dyspepsia Index-Korean version (NDI-K), and functional dyspepsia-related quality of life (FD-QoL). Results: No statistically significant differences were found in sex distribution, age, and body mass index between the patient group and the control group. As five questions affected the reliability negatively and three questions affected the clinical validity negatively, we decided to exclude the eight questions upon further investigation. The Cronbach's ${\alpha}$ coefficient of the revised FRQ-FD (17 items) was 0.899, and its clinical validity was verified. Construct validity was analyzed by factor analysis and produced five factors. Statistically significant positive correlations were found between the revised FRQ-FD and the other dyspepsia scales, namely, SQDQ, SSQD, VAS, NDI-K, and FD-QoL. VAS and NDI-K especially had strong positive correlations with FRQ-FD. Conclusions: The FRQ-FD developed in this study can provide fundamental reliability and validity for a pattern diagnosis questionnaire. FRQ-FD can help to diagnose food retention pattern in functional dyspepsia patients. Further studies are required to inspect several statistical factors.

• Journal of Broadcast Engineering
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• v.13 no.5
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• pp.696-706
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• 2008

In this paper we show the performance of the network-adaptive high-definition scalable video streaming using QWLAN board with IEEE 802.11e MAC monitoring and control. Realtime collected MAC parameters are used to determine which video data is extracted for the predicted available bandwidth. To achieve performance, extraction through R-D is proposed instead of the standard video packet extraction. It is shown through experiments that streaming video quality can be enhanced by fast adaptation to network conditions by using the proposed method.

• The KIPS Transactions:PartC
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• v.9C no.6
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• pp.865-874
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• 2002

HTTP (HyperText Transfer Protocol) is a transfer protocol used by the World Wide Web distributed hypermedia system to retrieve the objects. Because HTTP is a connection oriented protocol, it uses TCP (Transmission control Protocol) as a transport layer. But it is known that HTTP interacts with TCP badly. it is discussed about factors affecting the performance or HTTP over TCP, the transaction time obtained by the per-transaction TCP connections for HTTP access and the TCP slow-start overheads, and the transaction time for T-TCP (Transaction TCP) which is one or methods improving the performance or HTTP over TCP. Average waiting time and average turnaround time are important parameters to satisfy QoS (Quality of Service) of end users. Formulas for calculating two parameters are derived. Such formulas can be used for the environment in which each TCP or T-TCP transaction time is same or different. Some experiments and computational experiences indicate that the proposed formulas are well acted, can be applied to the environment which the extension of bandwidth is necessary, and time characteristics of T-TCP are superior to that of TCP. Also, the load distribution method of web server based on the combination of bandwidths is discussed to reduce average waiting time and average turnaround time.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.1
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• pp.35-40
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• 2019

It is important to constantly provide service in real-time multimedia applications using multicast. Transmission path reconstruction occurs in hybrid multicast using Internet Protocol (IP) multicast and ALM in order to adapt the network status to things like congestion. So, there is a problem in which real-time QoS is reduced, caused by an increase in end-to-end delay. In this paper, we want to solve this problem through multi-layer transmission path construction. In the proposed method, we deploy the control server and application layer overlay host (ALOH) in each multicast domain (MD) for hybrid multicast construction. After the control server receives the control information from an ALOH that joins the MD, it makes a group based on the hop count and sends it to the ALOH in each MD. The ALOH in the MD performs the role of sending the packet to another ALOH and constructs the multi-layered transmission path in order of priority by using control information that is received from the control server and based on the delay between neighboring ALOHs. When congestion occurs in, or is absent from, the ALOH in the upper MD, the ALOH selects the path with the highest priority in order to reduce end-to-end delay. Simulation results show that the proposed method could reduce the end-to-end delay to less than 289 ms, on average, under congestion status.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.2
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• pp.834-841
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• 2012

In order to the mobile service uses the wireless terminal including the development of the wire wireless network and Smart phone, and etc. use including mobile office, which and etc. increases. Because in order that the u-Healthcare service using this appeared before the footlights and the existing quality measurement reference considered the speed, error rate, and etc. just, guarantees the stability of the u-Healthcare, the quality control by service are necessary. In this paper, the quality measurement reference by mobile service considering the radio environment as the method for satisfying the quality guarantee of the u-Healthcare mobile service user and user needs was presented. The WiBro u-Healthcare wireless data service quality based system in the end user perspective was established through the main performance index and entrepreneur case presented in the international standardization institute including 3GPP, WiMAX forum, GSMA, and etc. through the related research and the validity of the quality index establishment was presented according to each service.