• The Journal of Korean Institute of Communications and Information Sciences
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• v.23 no.9A
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• pp.2184-2196
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• 1998

Admission control is one of the most important congestion control mechanism to be executed at the call set up phase by regulating traffic into a network in a preventive way. An efficient QOS evaluation or bandwidth estimation method is required for call admission to be decided in real time. In this paper, we spropose a computtionally simple approximation method of estimating cell loss probability and mean cell delay for admission control of both delay sensitive and loss sensitive calls. Mixed input queueing system, where a new call combines with the existing traffic, is used as a queueing model for QOS estimation. Also traffic parameters are suggested to characterize both a new call and existing traffic. Aggregate traffic is approximated by a renewal process with these traffic parameters and then mean delay and cell loss probability are detemined using appropriate approximation formulas. The accuracy of this approximation approach is examined by comparing their results with exact analysis or simulation results of vrious mixed unput queueing systems. Based on this QOS estimation method, call admission control scheme which is traffic independent and computable in yeal time are proposed.

• IE interfaces
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• v.2 no.1
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• pp.69-78
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• 1989

The objective of this study is to establish a hierarchical structure for Quality of Service Management (QOSM) from subsriber's viewpoint. First, We construct the hierarchy of the QOSM items. These items are derived from the CCITT concepts and the present Korean Telecommunication Authority(KTA) system. Then QOS performance indicators which consists of the lower levels of the hierarchy and the weight value is constructed. Finally, an evaluation method of the QOS is presented. It is expected that this study offers an evaluation method of network performance and efficiency of operation and maintenance for telecommunication facilities.

• Journal of the Korea Society for Simulation
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• v.14 no.1
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• pp.33-42
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• 2005

Service Level Agreement (SLA) is a service providing scheme by a service class agreement between a user and a service provider SLA allows that a user can select an expected service class in various service classes provided from a service provider. Recently, SLA management is adapted to support the end-to-end Qos for service users in Beyond 3 Generation (B3G) networks. In B3G networks, SLA provides multiple service classes on access networks so that service classes should be managed to assure the service satisfaction for users. In this paper, we propose a dynamic Qos management scheme by IP traffic class controlling based on SLA in B3G networks. Also, to manage dynamic traffic service, we consider Differentiated services (Diffserv) mechanism for the resource management by SLA. An If service traffic class on SLA can be dynamically changed by Diffserv traffic management to support dynamic end-to-end Qos. Hence, in this paper, we consider the buffer threshold scheme for controlling traffic loads and the traffic level control scheme for implementing the dynamic traffic management by the SLA.

• The Journal of Information Systems
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• v.8 no.1
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• pp.93-108
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• 1999

The switching system is designed and developed to satisfy the performance design objectives recommended by ITU for call processing capacity and quality of service(QOS), etc. When the results by actual measurement at the system testing phase do not satisfy the performance design objectives, however, an effort is required to improve the performance. This paper presents a method for improving QOS by modifying the application programs for the switching system. In the proposed method, the sequence chart related to a delay time for call connection is modelled using PERT(Program Evaluation and Review Technique) network. Then, the criticality index of a message is calculated using Monte Carlo simulation to evaluate which message's processing time to decrease in order to decrease the delay time and thus to improve QOS. The criticality index of a block is also calculated to identify those software blocks that significantly contribute to the delay time.

• The Journal of Engineering Research
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• v.3 no.1
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• pp.75-78
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• 1998

In this paper, we study the Qos in MPEG-2 services and analyze the MOS's method for the satisfaction with Qos when the user require.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.21 no.2
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• pp.447-460
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• 1996

Network optimization and design procedures often separate quality of service (QOS) performance measures from reliability issues. This paper considers channel allocation and flow assignment (routing) in a network subject to link failures. Fault-tolerant channel allocation and flow assingments are determined which minimize network cost while maintaining QOS performance requirements. this approach is shown to yield significant network cost reductions compared to previous heuristic methods used in the design of packet switched network with unreliable links.

• Journal of Korean Society of Transportation
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• v.27 no.1
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• pp.191-200
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• 2009

This study develops composite indicators that is capable of estimating QOS (Quality of Service) of pedestrians by enhancing estimation for Level of Service in present transporting spaces for pedestrians that merely concerns quantitative indicators such as pedestrian flow rate, pedestrian stoppage. This paper conducts survey questionnaire to collect data. It utilizes AHP(Analytic Hierarchy Process) and ANP(Analytic Network Process). The main results show that: first, ANP is better analytic methods than AHP due to the fact that pedestrians feel repetition when they judge level of service. Second, qualitative factors such as pedestrian behaviors, maintenance, scenary for pedestrians and environments should be considered. Importance of qualitative factors is higher in residential area than other areas. I expect that using qualitative indicators and quantitative indicators is appropriate in order to estimate pedestrians' QOS.

• Journal of Korean Academy of Nursing
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• v.46 no.6
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• pp.769-779
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• 2016

Purpose: This study was an experimental study to compare the inhalation effects of aroma essential oil on the quality of sleep (QOS) for shift nurses after working nights. Methods: The participants were 60 healthy adults who didn't have any disease. As an experimental treatment, the participants in the experimental group were asked to inhale essential oil for 3 minutes at a distance of approximately 10 cm from their nose and then they were asked to sleep with the aroma stone beside their head (within a 30 cm distance). QOS were measured four times on Pretest, Day 1, Day 2, and Day 3 after they slept. To measure QOS, Perceived QOS (Numeric Rating Scale), the Verran & Synder-Halpern (VSH) Sleep Scale were used, and number of awakenings (NoA) was measured by Actigraph. Results: There were no significant differences in the homogeneity tests for general characteristics and dependent variables prior to the experiments, except for VSH of subjective sleep quality. Also, there was no significant interaction between group and time. The VSH of the experimental group was higher than the control group (F=6.39, p=.002). The NoA between the experimental group and the control group was significantly different after experimental treatment 3rd day (F=13.35, p=.001). Conclusion: The findings show that the inhalation of aroma essential oil had effects to increase the quality of sleep. Therefore, the inhalation of aroma essential oil could be applied to general nursing interventions to improve the quality of sleep.

• Journal of the Korean Institute of Telematics and Electronics C
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• v.34C no.9
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• pp.22-32
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• 1997

This paper proposes an imprecise compuitation model for DCT considering QOS of images and a two dimensional DCT architecture for imprecise computations. In case that many processes are scheduling in a hard real time system, the system resources are shared among them. Thus all processes can not be allocated enough system resources (such as processing power and communication bandwidth). The imprecise computtion model can be used to provide scheduling flexibility and various QOS(quality of service)levels, to enhance fault tolerance, and to ensure service continuity in rela time systems. The DCT(discrete cosine transform) is known as one of popular image data compression techniques and adopted in JPEG and MPEG algorithms since the DCT can remove the spatial redundancy of 2-D image data efficiently. Even though many commercial data compression VLSI chips include the DCST hardware, the DCT computation is still a very time-consuming process and a lot of hardware resources are required for the DCT implementation. In this paper the DCT procedure is re-analyzed to fit to imprecise computation model. The test image is simulated on teh base of this model, and the computation time and the quality of restored image are studied. The row-column algorithm is used ot fit the proposed imprecise computation DCT which supports pipeline operatiions by pixel unit, various QOS levels and low speed stroage devices. The architecture has reduced I/O bandwidth which could make its implementation feasible in VLSI. The architecture is proved using a VHDL simulator in architecture level.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.4
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• pp.637-645
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• 2015

Recently, a spatial modulation (SM) scheme achieving high throughput based on quaternary quasi-orthogonal sequences (Q-QOSs), referred to as Q-QOS-SM, is presented for $N_t=2^n(n=1,2,{\cdots})$ transmit antennas. In this paper, based on the design approach of the conventional Q-QOS-SM, new improved QO-SM (I-QO-SM) schemes are proposed for 8 transmit antennas. The new schemes employ Q-QOSs of length 4 or 2 unlike of 8 in the original one, which guarantees more information bits to be allocated for antenna index parts compared to the conventional Q-QOS-SM. By computer simulation results, the proposed scheme are shown to enjoy much higher throughputs compared to the conventional other SM schemes for all simulation environments. Finally, we also examine and compare analytically the performances of the new and conventional SM schemes by calculating upper-bounds on BER performance.