• Journal of Communications and Networks
• /
• 제16권2호
• /
• pp.130-139
• /
• 2014

Due to the unpredictable nature of channel availability, carrying delay-sensitive traffic in cognitive radio networks (CRNs) is very challenging. Spectrum leasing of radio resources has been proposed in the so called coordinated CRNs to improve the quality of service (QoS) experienced by secondary users (SUs). In this paper, the performance of coordinated CRNs under fixed-rate with hard-delay-constraints traffic is analyzed. For the adequate and fair performance comparison, call admission control strategies with fractional channel reservation to prioritize ongoing secondary calls over new ones are considered. Maximum Erlang capacity is obtained by optimizing the number of reserved channels. Numerical results reveal that system performance strongly depends on the value of the mean secondary service time relative to the mean primary service time. Additionally, numerical results show that, in CRNs without spectrum leasing, there exists a critical utilization factor of the primary resources from which it is not longer possible to guarantee the required QoS of SUs and, therefore, services with hard delay constraints cannot be even supported in CRNs. Thus, spectrum leasing can be essential for CRN operators to provide the QoS demanded by fixed-rate applications with hard delay constraints. Finally, the cost per capacity Erlang as function of both the utilization factor of the primary resources and the maximum allowed number of simultaneously rented channels is evaluated.

• 유통과학연구
• /
• 제14권9호
• /
• pp.5-13
• /
• 2016

Purpose - This study proposes a framework for service innovation strategy to cope with the emergence of electric vehicles. Research design, data, and methodology - This study designs an electric-vehicle lease program and collects the resulting data to analyze. By analyzing the previous studies on the electric-vehicle market with cases, a theoretical framework based on existing theories is to be set. Results - This study proposes a strategy for the rapid diffusion of electric vehicles. First, a partitioned-pricing system is proposed to create an advantage for electric vehicles in terms of initial purchasing cost relative to traditional internal combustion vehicles. Second, focusing on reducing switching costs is important because electric vehicles have relatively low resale values due to the uncertainty of battery life. Third, a battery-leasing strategy is supposed to reduce the cost of switching from a traditional internal combustion vehicle to an electric vehicle. Conclusions - This paper can provide strategic guidance for decision makers in firms that have already entered the electric-vehicle leasing market by making a recommendation such as a service innovation strategy. The proposed strategy can be considered as an electric vehicle market in the future and can contribute to the wider diffusion of electric vehicles.

• 정보처리학회논문지D
• /
• 제9D권2호
• /
• pp.277-288
• /
• 2002

인터넷 마켓플레이스에서는 사용자를 도와주는 서비스 중개자가 가장 중요한 역할을 수행한다. 최근에 전자상거래나 온라인 쇼핑몰, 그리고 e-마켓플레이스를 위해 많은 지능적 중개자들이 개발되고 있다. 비록 이러한 시스템들은 많은 성공 사례를 보여주고 있지만 인터넷 마켓플레이스에서 요구되는 서비스 결합 및 자동 실행을 지원하는 시스템은 거의 없다. 이러한 관점에서 본 논문에서는 하나의 새로운 워크플로우 기반 서비스 중개가 시스템을 제안하다. 본 연구에서 종속된 서비스들은 워크플로우 프로세스로 표현되고 이 프로세스들은 워크플로우 엔진에 의해 자동 처리된다. 제안된 시스템에서 모든 데이터의 교환은 플랫폼 독립성, 확장성, 개방성, 그리고 상호운용성 구조를 제공하는 XML을 통해 구현된다.

• 한국항해항만학회지
• /
• 제28권8호
• /
• pp.709-714
• /
• 2004

본 연구는 최근 물동량이 빠른 속도로 증가하고 있는 대련항, 천진항, 청도항, 상해항 등을 화물의 목적항으로 설정하고, 선박의 운항패턴 시나리오를 바탕으로 부산항에서 환적하는 경우와 중국항 직기항 등의 총운송비용 차이를 분석하였다. 이를 바탕으로 하여 부산항에서 환적할 때 직기항하는 경우보다 초과 발생하는 비용을 항만 당국이 선사에게 보전해 주는 인센티브 규모로 하고, 이를 충당할 수 있는 전대사용료 산정 방법을 제시하였다.

• 산업공학
• /
• 제19권1호
• /
• pp.62-69
• /
• 2006

In these days companies are rapidly implementing the extended enterprise collaboration to provide enhanced management services and products based on the enterprise integration that human resources, technologies and the management process. In this corporate environment, ASP (Application Service Provider) which is the developed type of outsourcing in the area of information technology, is a good alternative for corporate information system management. ASP defines as a software leasing service which is supplied through networks instead of purchasing application software with high price. For successful implementation of ASP, it is necessary to develop the certification methodology to ensure safety and reliability of ASP. The paper provides the safe and reliable certification methodology for ASP. In order to develop it, the critical issues related to service quality and certification of ASP are identified and the systematic certification methodology of application and service provider(service environment) domains of ASP are provided. A evaluation method for the developed certification methodology is also proposed.

• 대한안전경영과학회지
• /
• 제7권3호
• /
• pp.97-108
• /
• 2005

The issue of using information system to ensure competitive power in the market is rising. The outsourcing methods that entrust activities of information system of companies to other expert agencies are increasing as the enterprises make a lot of efforts to put their resources to their heart of business in the process of adopting information system. Recently, ASP (Application Service Provider) as new information technology outsourcing method appears due to development of network technology and spreading of peculating software. ASP defines as a software leasing service which is supplied through networks instead of purchasing application software with high price. For successful implementation of ASP, it is necessary to develop a certification program to ensure safety and reliability of ASP. This paper provides the safe and reliable certification program for ASP. In order to develop it, the critical issues related to service quality and certification of ASP are identified and then evaluation methodology for ASP certification program is proposed. This paper presents application certification as the part of ASP certification program.

• Journal of Communications and Networks
• /
• 제15권1호
• /
• pp.102-110
• /
• 2013

This paper considers a cooperative orthogonal frequency division multiple access (OFDMA)-based cognitive radio network where the primary system leases some of its subchannels to the secondary system for a fraction of time in exchange for the secondary users (SUs) assisting the transmission of primary users (PUs) as relays. Our aim is to determine the cooperation strategies among the primary and secondary systems so as to maximize the sum-rate of SUs while maintaining quality-of-service (QoS) requirements of PUs. We formulate a joint optimization problem of PU transmission mode selection, SU (or relay) selection, subcarrier assignment, power control, and time allocation. By applying dual method, this mixed integer programming problem is decomposed into parallel per-subcarrier subproblems, with each determining the cooperation strategy between one PU and one SU. We show that, on each leased subcarrier, the optimal strategy is to let a SU exclusively act as a relay or transmit for itself. This result is fundamentally different from the conventional spectrum leasing in single-channel systems where a SU must transmit a fraction of time for itself if it helps the PU's transmission. We then propose a subgradient-based algorithm to find the asymptotically optimal solution to the primal problem in polynomial time. Simulation results demonstrate that the proposed algorithm can significantly enhance the network performance.

• 산업경영시스템학회지
• /
• 제29권1호
• /
• pp.101-108
• /
• 2006

The issue of using information system to ensure competitive power in the market is rising. The outsourcing methods that entrust activities of information system of companies to other expert agencies are increasing as the enterprises make a lot of efforts to put their resources to their heart of business in the process of adopting information system. Recently, ASP(Application Service Provider) as a new information technology outsourcing method appears due to the development of network technology and spreading of peculating software. ASP defines as a software leasing service which is supplied through networks instead of purchasing application software with high price. For successful implementation of ASP, it is necessary to develop a certification program to ensure safety and reliability of ASP. This paper provides the safe and reliable certification program for ASP. In order to develop it, the critical issues related to service quality and certification of ASP are identified and then evaluation methodology for the ASP certification program is proposed. This paper presents service provider(service environment) certification as the part of the ASP certification program.

• 대한산업공학회지
• /
• 제35권1호
• /
• pp.92-100
• /
• 2009

Today international trade through maritime transportation is significantly increasing. Due to this increase, shipping companies are faced with problems concerning the repositioning of empty containers from import dominant ports. The liner shipping service network has been provided to transport containers which load customers' freights. Container ships are moved on the liner shipping service network by observing the predetermined route and transportation time. This research deals with the empty containers distribution problem considering the container ship route. A mathematical model based on the mixed integer program has been introduced in this study. The objective is to minimize the total relevant costs of empty containers such as handling, leasing, and inventory holding, etc. Due to the complexity of the problem, a genetic algorithm has been suggested to solve large sized problems within a reasonable time. Numerical experiments have been conducted to show the efficiency of the genetic algorithm.

• 농촌계획
• /
• 제20권1호
• /
• pp.127-134
• /
• 2014

This study, in order to complement instability of analysis result stemming from the choice between reference point and comparison point which is pointed out as the defect of shift-share analysis, conducted shift-share analysis using Gross Regional Domestic Product (GRDP) trend of Geumgang area, Chungcheongnam-do for the period from 2000 to 2011. As a result of the analysis, (1) industries that had both the positive Regional Share Effect (RSE) and Industrial Mixed Effect (IME) were service industries such as manufacturing industry, electricity gas, transportation industry, art, etc., which are positively influencing the regional industry. (2) industries that had both the negative RSE and IME were other service industries such as wholesale and retail businesses, lodging industry, food industry, real estate business and leasing service, business service industry, public administration, etc., which provide basic livelihood services for the residents. (3) industries that had the positive RSE and negative IME were agriculture, forestry and fishery industry, mining industry, construction industry, and educational service industry. (4) industries that had the negative RSE and positive IME were info-communications industry, financial and insurance businesses, health industry, etc.