• International Journal of Advanced Culture Technology
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• v.8 no.3
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• pp.292-299
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• 2020

This paper presents an evaluation criteria of an information system availability for guaranteeing availability (service target level) from the perspective of the SLA contract and its technical point of view. In order to verify the effectiveness for information system failure and availability guarantee measures, three cases were examined. In summary, the failure time was reduced by 32% ~ 62% after applying the availability guarantee measure, verifying the excellence in the evaluation of an information system availability.

• THE INTERNATIONAL COMMERCE & LAW REVIEW
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• v.26
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• pp.203-223
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• 2005

Many international transactions involve the use of security devices, commonly referred to as "guarantees", "bonds", or "standby credits", designed to protect one of the parties from a breach by its counter-party. These security mechanisms may be provided by banks, insurance companies, specialized surety companies, or other financial service firms. Although some legal systems distinguish between "guarantees", "bonds", and "indemnities", these terms are often used as synonyms in the everyday language of international traders. It may therefore be necessary to examine the particular characteristics and nature of the guarantee obligation in order to properly classify the guarantee. Two main categories of guarantee are demand and suretyship. Under a demand guarantee, the guarantor must pay on first demand by the beneficiary. The beneficiary only has to demand payment under the guarantee - there is no need to prove that the principal has actually defaulted on a contractual obligation. Under a suretyship or conditional guarantee, the obligation of the guarantor is triggered by the actual default or contractual breach of the principal, as evidenced in a document such as a court judgement or arbitral award against the principal. Guarantees have been widely used in the international business transactions. Main uses of guarantees are as follows : Performance Bonds/Guarantees, Bid(or Tender) Bonds/Guarantees, Advance Payment or Repayment Bonds/Guarantees, Retention Bonds/Guarantees, Maintenance(or Warranty) Bonds/Guarantees etc.

• Journal of Communications and Networks
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• v.12 no.4
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• pp.346-357
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• 2010

Opportunistic scheduling provides the capability of resource management in wireless networks by taking advantage of multiuser diversity and by allowing delay variation in delivering data packets. It generally aims to maximize system throughput or guarantee fairness and quality of service (QoS) requirements. In this paper, we develop an extended proportional fair (PF) scheduling policy that can statistically guarantee three kinds of QoS. The scheduling policy is derived by solving the optimization problems in an ideal system according to QoS constraints. We prove that the practical version of the scheduling policy is optimal in opportunistic scheduling systems. As each scheduling policy has some parameters, we also consider practical parameter adaptation algorithms that require low implementation complexity and show their convergences mathematically. Through simulations, we confirm that our proposed schedulers show good fairness performance in addition to guaranteeing each user's QoS requirements.

• The KIPS Transactions:PartC
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• v.15C no.6
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• pp.547-556
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• 2008

Recently, with the advance of computing and networking technique, the high speed internet becomes widespread, however, it is still hard job to do streaming the media which requires high network bandwidth over the internet. Previous researches for streaming over the internet mainly proposed techniques that controls the QoS(Quality of Service) of the media in proportion to the network status. Though, this could be the solution for the service provider while the service user who wants constant QoS may not satisfy with variable QoS. In the paper, we propose a network adaptive prefetching technique, NAP, for guarantee of constant QoS. The NAP prefetches frames by increasing the frame transmission rate while the available network bandwidth is high. The NAP uses the prefetched frames to guarantee the QoS while the available network bandwidth is low. The experiment result shows that the proposed NAP could guarantee the constant QoS by prefetching the frames adaptively to the network bandwidth with the characteristic of video stream.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.11 no.6
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• pp.275-282
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• 2011

Current service discovery protocols such as UPnP, Jini, SLP provide the basic function which is message exchange pattern, service representation and description, in service discovery. They does not guarantee service interoperability among service discovery. Therefore, in this paper, we design and implement CLAM (Component-based Autonomic Layered Middleware) agent platform to enable an efficient service discovery through extension of DF agent function in FIPA-compliant specification. Also, we propose an efficient service discovery mechanism using DHT-Chord algorithm to guarantee scalability and interoperability in DF agent.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.8C
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• pp.758-770
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• 2002

In this paper, we propose a novel resource allocation scheme which can maximize capacity for QoS guarantee of Assured Service in Differentiated Services. Performance of the proposed resource allocation scheme is analyzed with each buffer management scheme such as RIO and Adaptive RIO. To prevent an early random drop of the admitted In-profile packet, Adaptive RIO scheme updates parameters of RIO scheme every time interval according to the estimated numbers of maximum packet arrivals of In-profile traffic and Out-of-profile traffic during the next time interval. The numbers of maximum packet arrivals during the next time interval are estimated based on the buffer size determined by the network topology and the ratio of bandwidth allocated to each subclass. We can find from simulation results that proposed resource allocation scheme with Adaptive RIO can guarantee QoS and can maximize capacity for Assured Service.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.26 no.11C
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• pp.10-23
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• 2001

It is difficult to satisfy the QoS(Quality of Service) guarantee which is required by real-time application services only with the Best-Effort(BE) service adopted in the current Internet. Therefore, worldwide research is being made on the method of QoS provisioning. Among them, the QoS guarantee mechanism using the Diffserv(Differentiated Service) was discussed in this paper. First we analyzed how the DiffServ performance was affected by traffic models. For this, we performed the research for the random, bursts, and self-similar traffic modeling method. We then designed and implemented an OPNET simulator, and performed the simulation 7d performance evaluation for diverse input parameters. Based on the results of performance evaluation, it was confirmed that QoS guarantee is possible for the EF(Expedited Forwarding) class with the DiffServ function under every environments considered and the service separation between EF and BE(Best Effort) classes is also possible. We also analyzed the performance variation and dynamic behavior of DiffServ mechanism based on the resource allocation between E? and BE classes in WFQ(Weighted Fair Queueing).

• Journal of information and communication convergence engineering
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• v.15 no.1
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• pp.28-36
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• 2017

The medium access control (MAC) protocol based on dynamic time division multiple access/time division duplex (TDMA/TDD) is responsible for random access control and radio resource allocation in dynamic traffic environments. These functions of random access and resource allocation are very important to prevent wastage of resources and improve MAC performance according to various network conditions. In this paper, we propose new random access and resource allocation schemes to guarantee quality of service (QoS) and provide priority services in a dynamic TDMA/TDD system. First, for the QoS guarantee, we propose an adaptive random access and resource allocation scheme by introducing an access probability. Second, for providing priority service, we propose a priority-based random access and resource allocation scheme by extending the first adaptive scheme in both a centralized and a distributed manner. The analysis and simulation results show that the proposed MAC protocol outperforms the legacy MAC protocol using a simple binary exponential backoff algorithm, and provides good differential performance according to priorities with respect to the throughput and delay.

• Journal of Distribution Science
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• v.13 no.1
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• pp.93-103
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• 2015

Purpose - This study plans to adopt a more sophisticated approach toward service recognition by customers in general supermarkets in order to revise the service quality measurement methods that suit the context of Korean distribution channels. In particular, in general supermarkets, where much of the shopping process is in the form of self-service, there is high reliance on the service recognized by the consumers; therefore, it is highly likely that consumers would make their purchasing decisions based on their recognition of service quality or guarantees. It also utilized service quality elements of a basic level in the KD-SQS development model in order to indicate that the quality recognized by consumers impacts their loyalty to the stores with financial value and abstract value. Research design, data, and methodology - The study suggested a theoretical model comprising 13 hypotheses on relations between theoretic variables, and conducted surveys with consumers using discount stores in Seoul and Gyunggi Metropolitan area in order to verify the hypotheses, while using SPSS 20.0, AMOS 21.0 as the verification program. The survey sheets used amounted to 332, and a structural equation model was used to analyze the reliability and validity of constituent elements and to verify the suggested hypothesis. Therefore, this study analyzes the interrelations between service quality and guarantee factors in the distribution channel and their relations with the loyalty to stores as a dependent variable. Results - First, the results of the hypotheses tests helped identify the relations between service quality, service guarantees, service value, and customer loyalty, providing an opportunity to define the relations between constituent elements. In particular, service convenience in service quality has no impact on financial values. Further, stores' service policy had no impact on abstract values. Service recognition by service convenience has an impact on abstract values such as good image, comfort, and usability, while mileage systems promote financial values for consumers. In order to improve consumer values in service quality and values, general supermarkets should improve their service convenience, membership, and mileage programs using various strategies. Conclusion - In order to improve consumer values in service quality and values, general supermarkets should improve their service convenience, membership, and mileage programs using various strategies. Further, as service guarantee systems have a significant and direct impact on customer loyalty, rather than customer value recognition, service guarantees should be used to encourage customers to re-visit the stores. Finally, this study applied the findings of preceding studies in terms of service quality measurement; it had limitations in referencing preceding studies in a comprehensive manner. It also had limits in expanding upon various preceding studies because it was difficult to apply new measurement tools due to the lack of service quality measurement tools for general supermarkets. Therefore, it is necessary to conduct more studies on service quality to measure service quality and develop measurement tools by incorporating various industry characteristics.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2001.05a
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• pp.575-578
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• 2001

Number Portability means that one can use his original telephone number when he change telephone service provider, region and the kind of service. Number portability is not necessary when only one telephone service provider exist in korea. But it is necessary to guarantee pair competition among the service providers as new communication service provider comes. The law which is related number portability is established by government as number portability is considered a tool to guarantee pair competition between old service provider and new service provider. A national standard on number portability with which all service provider can agree is needed. We developed functional standard for that purpose. Functional standard includes call processing structure, network requirement. This paper handle functional standards.