• Journal of Communications and Networks
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• 제15권2호
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• pp.207-216
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• 2013

Vehicular ad-hoc networks (VANETs) are self-organizing, self-healing networks which provide wireless communication among vehicular and roadside devices. Applications in such networks can take advantage of the use of simultaneous connections, thereby maximizing the throughput and lowering latency. In order to take advantage of all radio interfaces of the vehicle and to provide good quality of service for vehicular applications, we developed a seamless flow mobility management architecture based on vehicular network application classes with network-based mobility management. Our goal is to minimize the time of flow connection exchange in order to comply with the minimum requirements of vehicular application classes, as well as to maximize their throughput. Network simulator (NS-3) simulations were performed to analyse the behaviour of our architecture by comparing it with other three scenarios. As a result of this work, we observed that the proposed architecture presented a low handover time, with lower packet loss and lower delay.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2005년도 하계학술발표대회
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• pp.116-116
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• 2005

• Asian Journal of Business Environment
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• 제9권1호
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• pp.21-28
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• 2019

Purpose - The purpose of this paper is to investigate the relationship between corporate social responsibility disclosure (CSRD) and investment-cash flow sensitivity, which is a surrogate for financing constraints. Research design, data, and methodology - Taking China's A-share listed companies between 2009 and 2016 as a sample, this paper empirically tests the relationship between CSRD and investment-cash flow sensitivity by Panel VAR model. By introducing the orthogonal impulse response function, this paper distinguishes the fundamental factors and financial ones that affect corporate investment behavior. Results - Findings indicate that: (1) investment-cash flow sensitivity of firms with low level of CSRD is significantly lower than that of firms with high level of CSRD; (2) the orthogonal impulse response of corporate investment to cash flow in firms with high level of CSRD is significantly different from zero, but it is not significant in firms with low level of CSRD; (3) for firms with low level of CSRD, 0.7% of corporate investment volatility can be explained by the change in cash flow, which is lower than that of firms with high level of CSRD (1.1%). Conclusions - Corporations disclosing more and higher quality CSRD are often those faced with financing constraints. Voluntary disclosure can help them alleviate information asymmetry and financing constraints.

• 인터넷정보학회논문지
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• 제22권6호
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• pp.1-8
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• 2021

With the rapid growth of intelligent devices and communication technologies, 5G network environment has become more heterogeneous and complex in terms of service management and orchestration. 5G architecture requires supportive technologies to handle the existing challenges for improving the Quality of Service (QoS) and the Quality of Experience (QoE) performances. Among many challenges, traffic steering is one of the key elements which requires critically developing an optimal solution for smart guidance, control, and reliable system. Mobile edge computing (MEC), software-defined networking (SDN), network functions virtualization (NFV), and deep learning (DL) play essential roles to complementary develop a flexible computation and extensible flow rules management in this potential aspect. In this proposed system, an accurate flow recommendation, a centralized control, and a reliable distributed connectivity based on the inspection of packet condition are provided. With the system deployment, the packet is classified separately and recommended to request from the optimal destination with matched preferences and conditions. To evaluate the proposed scheme outperformance, a network simulator software was used to conduct and capture the end-to-end QoS performance metrics. SDN flow rules installation was experimented to illustrate the post control function corresponding to DL-based output. The intelligent steering for network communication traffic is cooperatively configured in SDN controller and NFV-orchestrator to lead a variety of beneficial factors for improving massive real-time Internet of Things (IoT) performance.

• 한국멀티미디어학회논문지
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• 제17권12호
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• pp.1453-1460
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• 2014

WFQ (Weighted Fair Queuing) provides not only fairness among traffic flows in using bandwidth but also guarantees the Quality of Service (QoS) that individual flow requires, which is why it has been applied to the resource reservation protocol (RSVP)-capable router. The RSVP allocates an enough resource to satisfy both the rate and end-to-end delay requirements of the flow in the condition of no packet loss, and the WFQ scheduler guarantees those QoS requirements with the allocated resource. In practice, however, most QoS-guaranteed services allow a degree of packet loss, especially from 0.1% to 3% for Voice over IP. This paper discovers that the packet loss rate of each traffic flow is determined by only its time-stamp adjustment value, and then enhances the WFQ to provide a differentiated packet loss guarantee under general traffic conditions in terms of both traffic characteristics and QoS requirements. The performance evaluation showed that the proposed WFQ could increase the utilization of bandwidth by 8~11%.

• 대한전자공학회논문지TC
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• 제41권2호
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• pp.31-40
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• 2004

Diff-Sew는 개별적으로 구분된 다른 트레픽에 대해서 다른 종류의 네트워크 서비스를 제공하기 위한 메카니즘이며 이용자들에게 양질의 서비스를 제공하기 위한 방법을 제시하고 있다. DS는 토큰 버켓 방법을 사용하여 고정된 호스트들에게 제공되기 때문에 이동성을 가지는 서비스나 개별적인 트레픽에 대한 차등적인 서비스를 제공할 방안이 존재하지 않는다 본 논문에서는 트래픽컨테이너(TC)를 위해서 WFQ 방법과 변방 노드들과 경계 라우터들 내부에서 제어가 가능한 AggF(Aggregate Flow)를 모니터링하여 스케쥴링하는 방법을 제시한다. 이 방법은 트래픽 비율(traffic rate)을 유동적으로 제어가 가능하며 대역폭의 효율적인 이용성을 제공하고 있다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제7권1호
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• pp.38-55
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• 2013

Wireless network systems provide fast data transmission rates and various services to users of mobile devices such as smartphones and smart pads. Because many people use high-performance mobile devices, the use of real-time multimedia services is increasing rapidly. However, the preoccupation of resources by real-time traffic users is causing harm to other services-for example, frequent call interference, lowered service quality, and poor network performance. This paper suggests a resource allocation algorithm for effective traffic service support in a hybrid network. The main objective is to obtain an optimum value of data rates by comparing user requirements with the amount of resources that can be allocated. A new mechanism based on Adaptive-Quality of Service (QoS) and a monitoring system based on Queue-Aware are proposed. Adaptive-QoS supports effective resource control according to the type of traffic service, and the monitoring system based on Queue-Aware measures the amount of resources in order to calculate the maximum that can be allocated. We apply our algorithm to a test system and use Qualnet 4.5.1 to evaluate its performance.

• 기술경영경제학회:학술대회논문집
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• 기술경영경제학회 2000년도 제17회 하계학술발표회 논문집
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• pp.47-64
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• 2000

This paper analyses characteristics of the numerical controller industry in market formation and the Flow of information between users and producers and the characteristic of knowledge base of the industry and discusses the difficulties derived, from the characteristics, in accumulation of technological capability In market formation betweenusers and producers, the multi-layered market is not favorable to domestic producers in that lower end market is not large enough to provide cardle market to them which produce inferior quality and lower price than importer products. The credibility of the permance of a product is difficult to prove until a critical mass of products are sold. Therefore gaining market share is deterred by unproven credibility of the performance of the product. The flow of information between users and producers is limited. The flow of information on users environment through mass market to producers is essential for improving credibility of a product. The nature of knowledge base is tacit and the means of knowledge transmission is limited. Technological licensing and reverse engineering, Which have been conventional industry. These characteristics provide conditions of vicious circle in accumulation of technological capability of the numerical controller industry. This paper argues that these characteristics of the industry challenges existing approach to R&D management and framework of science and technology policy.

• 한국기술혁신학회:학술대회논문집
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• 한국기술혁신학회 2001년도 춘계학술대회:발표자료
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• pp.411-430
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• 2001

This Paper analyses characteristics of the numerical controller industry in market formation and the flow of information between users and producers and the characteristic of knowledge base of the industry and discusses the difficulties derived, from the characteristics, in accumulation of technological capability In market formation between users and producers, the multi-layered market is not favorable to domestic producers in that lower end market is not large enough to provide cradle market to them which produce inferior quality and lower price than imported products. The credibility of the performance of a product is difficult to prove until a critical mass of products are sold. Therefore gaining market share is deterred by unproven credibility of the performance of the product. The flow of information between users and producers is limited. The flow of information on users environment through mass market to producers is essential for improving credibility of a product. The nature of knowledge base is tacit and the means of knowledge transmission is limited. Technological licensing and reverse engineering, which have been conventional means of knowledge transmission, are not useful in the numerical controller industry. These characteristics provide conditions of vicious circle in accumulation of technological capability of the numerical controller industry. It is conjectured that these characteristics are derived from the fact that the numerical controller is the result of IT based technological convergence in controlling machining process. This paper argues that these characteristics of the industry challenges existing approach to R&D management and framework of science and technology Policy.

• 기술혁신연구
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• 제9권1호
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• pp.149-165
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• 2001

This paper analyses characteristics of the numerical controller industry in market formation and the flow of information between users and producers and the characteristic of knowledge base of the industry and discuses the difficulties derived, from the characteristics, in accumulation of technological capability. In market formation between users and producers, the multi-layered market is not favorable to domestic producers in that lower end market is not large enough to provide cradle market to them which produce inferior quality and lower price than imported products. The credibility of the performance of a product is different to prove until a critical mass of products are sold. Therefore gaining market share is deterred by unproven credibility of the performance of the product. The flow of information between users and producers is limited. The flow of information on users environment through mass market to producers is essential for improving credibility of a product. The nature of knowledge base is tacit and the means of knowledge transmission is limited. Technological licensing and reverse engineering, which have been conventional means of knowledge transmission, are not useful in the numerical controller industry. These characteristics provide conditions of vicious circle in accumulation of technological capability of the numerical controller industry. This paper argues that these characteristics of the industry challenge existing approach to R&D management and framework of science and technology policy.