Jonghwan Kim

Mobility support in content centric networks

Content-centric networking (CCN) is designed for efficient dissemination of information. Several architectures are proposed for CCN recently, but mobility issues are not considered sufficiently. We classify traffic types of CCN into real-time and non real-time. We examine mobility problems for each type, and suggest the possible hand-off schemes over CCN. Then, we analyze the delay performance in terms of simulation study. We believe that the proposed schemes can be merged as a part of the CCN easily, since they comply with the inherent nature and rules of the CCN.

Youngia denticulata Protects Against Oxidative Damage Induced by tert-Butylhydroperoxide in HepG2 Cells

Improvement of liver function is one of the most popular commercial health claims of functional foods in Asian countries, including Korea. After examining the potential of several traditional Korean wild vegetables for enhancing liver function, we found that Youngia denticulata Kitam. has strong hepatoprotective effects against oxidative stress induced by tert-butylhydroperoxide (t-BHP). We are the first to report that the extract and ethyl acetate fractions of Y. denticulata have radical scavenging activities and inhibit oxidative stress-induced cell death and DNA damage in HepG2 cells. The extract and ethyl acetate fractions significantly decreased cellular reactive oxygen species production and apoptosis induced by t-BHP in HepG2 cells. In addition, they prevented the depletion of cellular glutathione, which is an important defense molecule against oxidizing xenobiotics. Chlorogenic acid and 3,5-dicaffeoylquinic acid were found to be major active components responsible for the activity of Y. denticulata and could serve as marker compounds for standardization. These data suggest that Y. denticulata could be promoted as a potential antioxidative functional food candidate, particularly for hepatoprotection against oxidative stress.

End-to-end mobility support in content centric networks

Content-centric networking CCN has been recently proposed as an alternative to traditional IP-based networking. In CCN, content is accessed by content name instead of a host identifier locational identifier. This new type of access methodology rapidly and efficiently disseminates content in combination with the in-network caching mechanism. For practical use of CCN, many network properties studied in IP-based networking are being revisited, and new types of CCN architecture components are being designed. Although mobility is an essential aspect of the future networking system, it has not been sufficiently studied. We therefore address fundamental mobility issues, such as seamless handover, optimal access point selection, network mobility, and handling of persistent interests. In addition, for each issue, we propose practical solutions that efficiently align to a CCN environment. To ensure seamless handoff, we propose various handoff schemes and compare their performance in terms of handoff latency using packet-level simulation. Because our proposed schemes are consistent with the characteristics and rules of CCN, we believe that they can easily be integrated as a part of CCN. Copyright

Efficient content delivery in mobile ad-hoc networks using CCN

Information-centric networking (ICN) is emerging as a future network technology. It has introduced the great advantage of information dissemination with low bandwidth consumption in wired testbed networks. Recently, ICN is also studied for mobile ad-hoc networks environments for efficient content distribution. In the existing works in the literature, broadcast delivery is actively utilized for designing new routing schemes since it seems well fitted to the nature of ICN conceptually. In this paper, we raise questions about this research direction by analysing the performance of reliability and energy efficiency of both broadcast and unicast delivery schemes. Our analysis shows that unicast delivery outperforms broadcast delivery, unless topological changes incur too much packet flooding overhead. Based on this observation, we present a novel energy efficient content distribution scheme that delivers the content in a unicast manner while minimizing flooding overhead by taking advantage of ICN features. Via ns-3 simulation, we compare the performance of the proposed scheme with that of other comparative schemes, and show that the proposed scheme achieves much higher reliability and energy efficiency in content distribution under mobile ad-hoc network environments.

Controlled Queue Management in Software-Defined Networks

Software-defined networking (SDN) has emerged as one of the future internet technologies. It separates the control plane and the data plane, keeping the data plane simple by assigning the complex computing to the control plane. Active queue management (AQM) has been researched to obtain lower delay and higher throughput. It is noteworthy to have these advantages in SDN. To bring AQM to SDN without harming the simplicity of the data plane, we present Controlled Queue Management. The proposed scheme takes advantage of the global view of networks, and immigrates complex computations from routers to controllers. Simulation shows that the proposed scheme stably manages queues, effectively utilizing the global view of networks.

Screen acceleration VNF scheme in NFV for VDI service

As the cloud-based datacenter with SDN (Software Defined Network) enabled has been deployed as a real service platform, NFV (Network Function Virtualization) attracts great attention from many researchers. NFV virtualizes network equipment to implement elastic network service in the cloud. Specifically, in this paper, we propose screen acceleration VNF (Virtual Network Function) scheme that makes VDI (Virtual Desktop Infrastructure) service dynamically operational in the cloud and NFV platform.