• 한국철도학회:학술대회논문집
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• 한국철도학회 2007년도 추계학술대회 논문집
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• pp.191-196
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• 2007

This paper is reviewed RAM(Reliability, Availability and Maintainability) data table utilized for RAM data management to Urban Maglev Transit. As railway systems become more complex, the RAM requirements are reinforced to ensure that a design meets Reliability, Availability, Maintainability criteria. Therefore, it needs the efficient management for RAM data of railway system to meet RAM target. At this study, RAM data management format is suggested to ensure reliability and maintainability based on acquired experience for overseas rolling stock. This RAM data table and FMECA(Failure Mode Effect Criticality Analysis) table are useful to the calculation of MTBF(Mean Time Between Failure), MTBSF(Mean Time Between Service Failure) and Maintainability. Also, this RAM management table will be efficient to improve the RAM evaluation to Urban Maglev Transit.

• 한국의상디자인학회지
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• 제10권3호
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• pp.149-161
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• 2008

Internet shopping provides convenience to consumers, however, in recent years the consumer's return rate and return-related disputes continue to increase. This article examines the characteristics of return behavior through return experiences of internet clothing purchases. For an empirical study, questionnaires were handed out to 317 undergraduate male and female students, in which the results had been used for data analysis. Data were analyzed through SPSS 12.0 software, descriptive statistics, factor analysis, t-test, ANDVA analysis, Duncan test, and $x^2-test$. The results are the following: The analysis of consumers' return factor for clothes in Internet shopping showed there are five factors: product and quality, delivery, impulse buying, change of mind, and service. There is a significant difference in product quality of return factors depending on the availability of the return experience. Thus, consumers with return experience showed more return tendency owing to product quality factor than consumers without return experience. The availability of consumer's return experience was significantly related to information search. Consumers with return experience showed more consistent information search than consumers without return experience. There were significant differences in perceived risks depending on the availability and degree of consumer's return experience. In other words, consumers with return experience perceived more account related risk than consumers without return experience. Moreover, the more return experience the consumer has, the more risks consumers perceived in product performance.

• 한국정보시스템학회지:정보시스템연구
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• 제27권2호
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• pp.197-219
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• 2018

Purpose The purpose of this study is to examine what motivates users to adopt one of the emerging applications for collaborative consumption of sharing economy. Using the self-determination theory, motivation theory and TAM(Technology Acceptance Model) as the theoretical framework, this study illustrates important factors that influence adoption of collaborative consumption service. We develops the ICTs(Information and Communications Technologies) initiatives and motivation model to collaborative consumption. Design/methodology/approach This paper makes use of a quantitative methodology using survey questionnaire that allows for the measurement of the eight constructs(System Availability, Contents Quality, Design & Personalization, Security & Privacy, Emotional & Social Value, Economic Value, Attitude, Adoption & Consumption) contained in the hypothesized theoretical model on the basis of the prior literatures. Data collected from a sample of 227 respondents who have used the collaborative consumption services and provided the foundation for the examination of the proposed relationships in the model. Findings This study has the following implications for the users and providers of CC platforms and services. The ICTs initiatives (System Availability, Contents Quality, Design & Personalization, Security & Privacy) are the influential factors that motivate the emotional and social value to CC. On the other hand, The ICTs initiatives (System Availability, Contents Quality) are not very significant factors of economic value to CC. The empirical analysis result indicate that there are significant causal effect among emotional & social value, economic value, and adoption to CC. This study provides important theoretical implications for innovation adoption research through an empirical examination of the relationship between ICTs initiatives, motivation factors to collaborative consumption in the sharing economy.

• Advances in Computational Design
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• 제3권2호
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• pp.201-212
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• 2018

Decrease in availability of suitable subbase and base course materials for highway construction leads to a search for economic method of converting locally available troublesome soil to suitable one for highway construction. Present study insights on evaluation of benefits of stabilization of subgrade soils in term of extension in service life (TBR) and layer thickness reduction (LTR). Laboratory investigation consisting of Atterberg limit, Compaction, California Bearing Ratio, unconfined compressive strength and triaxial shear strength tests were carried out on two types of soil for varying percentages of stabilizers. Vertical compressive strains at the top of unstabilized and stabilized subgrade soils were found out by elastoplastic finite element analysis using commercial software ANSYS. The values of vertical compressive strains at the top of unstabilized and stabilized subgrade, were further used to estimate layer thickness reduction or extension in service life of the pavement due to stabilization. Finite element modeling of the flexible pavement layered structure provides modern technology and sophisticated characterization of materials that can be accommodated in the analysis and enhances the reliability for the prediction of pavement response for improved design methodology. If the pavement section is kept same for unstabilized and stabilized subgrade soils, pavement resting on lime, fly ash and fiber stabilized subgrade soil B will have service life 2.84, 1.84 and 1.67 times than that of unstabilized pavement respectively. The flexible pavement resting on stabilized subgrade is beneficial in reducing the construction material. Actual savings would depend on the option exercised by the designer for reducing the thickness of an individual layer.

• 한국시뮬레이션학회논문지
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• 제12권3호
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• pp.83-94
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• 2003

For 24 hours-7 days service on distributed systems, a great deal of efforts are investigated on high availability for seamless operation. In this paper, we propose a dynamic reconfiguration framework of distributed systems, called "hot-swapping" framework. This framework allows us to upgrade and exchange a number of modules of a distributed system without stopping running service as well as the system itself. In order to hide the state of service operation, the framework employes the "proxy" design pattern. Our framework provides two types of proxies: a static proxy and a dynamic proxy, Static proxies can achieve fast execution time, but they need to be changed whenever any minor change exists in the related swappable module. Meanwhile, dynamic proxies takes longer execution time, but do not need to be changed under minor changes of swappable modules. We compare performances of static and dynamic proxies and also apply the framework to a real situation with security management modules. management modules.

• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2014년도 추계학술발표대회
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• pp.227-230
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• 2014

LTE 3GPP standard defines several QCI (QoS Class Identifier) classes to provide differential QoS, depending on the requirements of different user applications.These QCI values have been characterized in terms of priority, packet loss and delay budget. In spite of the availability of this robust QoS framework in LTE, there is no such scheduling algorithm that has its working principle based on this framework. The responsibility of fulfilling the user requirements, while satisfying the service class requirements is left upon the cellular service provider and it is an open issue at present. To solve this problem, we have proposed a MAC scheduler, which defines the priority of different users based on their bearer specification and provides desired QoS in terms of the achieved throughput through the resource block allocation based on calculated user priority.

• 디지털융복합연구
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• 제12권5호
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• pp.1-12
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• 2014

최근 인터넷 뱅킹, 전자결제, 전자상거래, 홈쇼핑, 증권 거래, 민원 업무 등 미션 크리티컬한 비즈니스가 증가함에 따라 무정지 서비스에 대한 요구가 높아지면서, 기존의 단일 데이터베이스에서 클러스터링, 이중화 기법 등에 관한 고가용성 기법에 관한 연구가 증가하고 있다. ALTIBASE$^{TM}$ Log Analyzer(이하 ALA)는 이중화 기법과는 별개로 Active Log를 기반으로 API를 제공하여, 이기종 또는 동일 기종간의 통신 및 확장성을 제공한다. 본 논문에서는 ALA를 사용하여 고가용성과 고확장성, 실시간 동기화 기능을 모두 만족시킬 수 있는 데이터베이스 시스템의 설계를 제시하고 ALA에 대한 성능평가를 하였다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제9권3호
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• pp.843-871
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• 2015

Cloud computing evolve as a cost effective business model for IT companies to focus on their core business without perturbing on infrastructure related issues. Hence, major IT firms and Small & Medium Enterprises (SME) are adopting cloud services on rental basis from cloud providers. Cloud Service level agreements (SLA) act as a key liaison between consumers and providers on renting Anything as a Service (AaaS). Design of such an agreement must aim for greater profit to providers as well as assured availability of services to consumers. However in reality, cloud SLA is not satisfying the parties involved because of its inherent complex nature and issues. Also currently most of the agreements are unilateral to favour the provider. This study focuses on comprehensive, 360-degree survey on different aspects of the cloud service agreements. We detailed the life cycle of SLA based on negotiation, different types of SLA, current standards, languages & characteristics, metrics and issues involved in it. This study will help the cloud actors to understand and evaluate the agreements and to make firm decision on negotiation. The need for standardized, bilateral, semantic SLA has also been proposed.

• Journal of Positioning, Navigation, and Timing
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• 제11권4호
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• pp.269-277
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• 2022

In this paper, we overview the system development status of the national maritime precise point positioning-real-time kinematic (PPP-RTK) service in Korea, also known as the Precise POsitioning and INTegrity monitoring (POINT) system. The development of the POINT service began in 2020, and the open service is scheduled to start in 2025. The architecture of the POINT system is composed of three provider-side facilities-a reference station, monitoring station, and central control station-and one user-side receiver platform. Here, we propose the detailed functionality of each component considering unidirectional broadcasting of augmentation data. To meet the centimeter-level user positioning accuracy in maritime coverage, new reference stations were installed. Each reference station operates with a dual receiver and dual antenna to reduce the risk of malfunctioning, which can deteriorate the availability of the POINT service. The initial experimental results of a testbed from corrections generated from the testbed network, including newly installed reference stations, are presented. The results show that the horizontal and vertical accuracies satisfy 2.63 cm and 5.77 cm, respectively. For the purpose of (near) real-time broadcasting of POINT correction data, we designed a correction message format including satellite orbit, satellite clock, satellite signal bias, ionospheric delay, tropospheric delay, and coordinate transformation parameters. The (near) real-time experimental setup utilizing (near) real-time processing of testbed network data and the designed message format are proposed for future testing and verification of the system.

• 융합경영연구
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• 제11권2호
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• pp.1-11
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• 2023

Purpose: With the rapid development of e-commerce, logistics services, as an important part of e-commerce shopping, have gradually attracted people's attention. Customer engagement behavior is a new topic in marketing, and its connotation is still being explored. The purpose of this paper is to study the relationship between logistics service quality and customer engagement behavior. Research design, data and methodology: This study employed the method of online questionnaire survey, with Chinese e-commerce platform users as the survey objects, 248 valid survey sample data were collected, and the method of factor analysis and structural equation model analysis was used to verify the research hypothesis model constructed in this paper. Results: The four dimensions of e-commerce logistics service quality have different influences on customer satisfaction, and the influence of availability on customer satisfaction is not significant. Convenience, assurance, and security have a significant positive impact on customer satisfaction; Customer satisfaction has a significant positive impact on the three dimensions of customer engagement behavior: customer repeat purchase behavior, online word-of-mouth, and customer referrals. Conclusion: The results of this study will provide useful reference for the managers of e-commerce companies to improve customer engagement behavior by improving the logistics service quality.