• Journal of the Korea Computer Industry Society
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• v.5 no.1
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• pp.39-48
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• 2004

An IP address shortage problem is happening with a rapid propagation of the Internet and demands about a new IP address. Address translation technology as NAT is becoming use widely in order to solve these problems. NAT is an very useful If address translation technique that allows two connected networks to use different and incompatible IP address schemes. Rut it is difficult to use NAT particularly for applications that embeded IP addresses in data payloads or encrypted IP packet to guarantee End-to-End Security such as IPSec. In addition to rewiting the source/destination IP address in the packet, NAT must modify IP checksum every time, which could lead to considerablely performance decrease of the overall system in the process of address translation. RSIP is an alternative to solve these disadvantages and address shortage problems of NAT. Both NAT and RSIP divide networks into inside and outside addressing realms. NAT translates addresses between internal network and external network, but RSIP uses a borrowed external address for outside communications. RSIP server assigns a routable, public address to an RSIP client temporaily to communicate with public network outside the private network. In this paper, I will analyze NAT and RSIP gateway system, and then I will propose the Linux-based RSIP gateway for more efficient IP Address Translation in Intranet environments based on RSIP standard of IETF.

• Radiation Oncology Journal
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• v.18 no.3
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• pp.167-176
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• 2000

The objective of recent radiation therapy is to improve the quality of treatment and the after treatment quality of life. In Korea, sharing the same objective, significant advancement was made due to the gradual increase of patient number and rapid increase of treatment facilities. The advancement includes generalization of three-dimensional conformal radiotherapy (3D-CRT), application of linac-based stereotactic radiosurgery (SRS), and furthermore, the introduction of intensity modulated radiation therapy (IMRT). Authors in this paper prospectively review the followings: the advancement of radiation oncology in Korea, the recent status of four-dimensional radiation therapy, IMRT, the concept of the treatment with biological conformity, the trend of combined chemoradiotherapy, the importance of internet and radiation oncology information management system as influenced by the revolution of information technology, and finally the global trend of telemedicine in radiation oncology. Additionally, we suggest the methods to improve radiotherapy treatment, which include improvement of quality assurance (QA) measures by developing Koreanized QA protocol and system, regional study about clinical protocol development for phase three clinical trial, suggestion of unified treatment protocol and guideline by academic or research societies, domestic generation of treatment equipment's or system, establishment of nationwide data base of radiation-oncology-related information, and finally patterns-of-care study about major cancers.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.5 no.3
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• pp.27-45
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• 2010

It is strongly believed that multicast will become one of the most promising services on internet for the next generation. Multicast service can be deployed either on network-layer or application-layer. IP multicast (network-layer multicast) is implemented by network nodes (i.e., routers) and avoids multiple copies of the same datagram on the same link. Despite the conceptual simplicity of IP multicast and its obvious benefits, it has not been widely deployed since there remain many unresolved issues. As an alternative to IP multicast, overlay multicast (application-layer multicast) implements the multicast functionality at end hosts rather than routers. This may require more overall bandwidth than IP multicast because duplicate packets travel the same physical links multiple times, but it provides an inexpensive, deployable method of providing point-to-multipoint group communication. In this paper we develop an efficient method applied greedy algorithm for solving two models of overlay multicast routing protocol that is aimed to construct MDST (Minimum Diameter Spanning Tree : minimum cost path from a source node to all its receivers) and MST (Minimum Spanning Tree : minimum total cost spanning all the members). We also simulate and analyze MDST and MST.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.5B
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• pp.430-441
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• 2006

As the various A/V devices and home networks are delivered to users, home networks are changing to an entertainment network. It is expected that the required network bandwidth and the amount of usage of media content in home entertainment networks will be increased. Although the access networks and home networks becoming a high speed network, there remains the problems for QoS-guaranteed media content transfer in home networks. Also, in the home network, there can be network traffic caused by applications like video conferencing, video telephone, and VoIP(voice over IP) as well as inner network traffic of home network. Since media content transfer requires the real-time delivery, it is very important and basic requirement that is to transfer media content to A/V device user wants while keeping the media quality. Even though there are many middleware protocol for home networking, they provide basic device discovery and control or simple functions for QoS-guaranteed media content transfer that are not enough to provide QoS-guaranteed media transfer service that user wants. Thus, in this paper, we propose the technique based on UPnP(universal plug and play) protocol for QoS-guaranteed media content transfer in the home network. The proposed technique is compatible with UPnP and can be used with UPnP as additional functions. In this paper, we utilize VideoLAN application to verify the proposed technique. We add the additional modules that support the proposed technique's function to VideoLAN and we verify the its functions through various test scenarios.

• Journal of KIISE:Information Networking
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• v.29 no.6
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• pp.722-737
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• 2002

As the number of multimedia applications increases, various protocols and architectures have been proposed to provide QoS(Quality of Service) guarantees in the Internet. Most of these techniques, though, bear inherent contradiction between the scalability and the capability of providing QoS guarantees. In this paper, we propose a protocol, named DQSP(Dynamic QoS Support Protocol), which provides the dynamic resource allocation and admission control for QoS guarantees in a scalable way. In DQSP, the core routers only maintain the per source-edge router resource allocation state information. Each of the source-edge routers maintains the usage information for the resources allocated to itself on each of the network links. Based on this information, the source edge routers perform admission control for the incoming flows. For the resource reservation and admission control, DQSP does not incur per flow signaling at the core network, and the amount of state information at the core routers depends on the scale of the topology instead of the number of user flows. Simulation results show that DQSP achieves efficient resource utilization without incurring the number of user flow related scalability problems as with IntServ, which is one of the representative architectures providing end-to-end QoS guarantees.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38B no.5
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• pp.394-400
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• 2013

WoT (Web of Things) was proposed to realize intelligent thing to thing communications using WEB standard technology. It is difficult to adapt security protocols suited for existing Internet communications into WoT directly because WoT includes LLN(Low-power, Lossy Network) and resource constrained sensor devices. Recently, IETF standard group propose to use DTLS protocol for supporting security services in WoT environments. However, DTLS protocol is not an efficient solution for supporting end to end security in WoT since it introduces complex handshaking procedures and high communication overheads. We, therefore, divide WoT environment into two areas- one is DTLS enabled area and the other is an area using lightweight security scheme in order to improve them. Then we propose a mutual authentication scheme and a session key distribution scheme for the second area. The proposed system utilizes a smart device as a mobile gateway and WoT proxy. In the proposed authentication scheme, we modify the ISO 9798 standard to reduce both communication overhead and computing time of cryptographic primitives. In addition, our scheme is able to defend against replay attacks, spoofing attacks, select plaintext/ciphertext attacks, and DoS attacks, etc.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.1
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• pp.54-61
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• 2007

In this paper, on-demand service streaming protocol for user-created contents in digital cable broadcasting environment is considered. In order to provide variety media contents service like UCC in digital cable broadcasting environment, the same service model as RVOD(Real Video on Demand) is required and the different interface for each broadcasting platform is needed in a current OCAP environment. Using return path based RTP, we separate existing VOD stream band into broadcasting and VOD stream band. In order to broaden On-demand service, consistent expansion of the infrastructure same as live broadcasting system is inefficient in the digital cable broadcasting environment. Using existing network protocol, the service which is insensitive to the infrastructure for VOD service becomes possible. Therefore we considered the analysis of the class of download available structure in the Set-Top-Box for RTP(Real-time Transport Protocol) and designing the decoding available streaming server for UCC transcoding and transmission in the receiver. Designing a efficient VOD service and system under the broadcasting environment gives a expansion of On-Demand service and more chance to upload and utilization of contents.

• Journal of KIISE:Information Networking
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• v.30 no.4
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• pp.559-571
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• 2003

ENUM(tElephon NUmbering Mapping) is protocol that brings convergence between PSTN Networks and IP Networks using a unique worldwide E.164 telephone number as an identifier between different communication infrastructure. The mechanism provides a bridge between two completely different environments with E.164 number; IP based application services used in PSTN networks, and PSTN based application services used in IP networks. We propose a new way to organize and handle ENUM Tier 2 name servers to improve performance at the name resolution process in ENUM based application service. We build an ENUM based network model when NAPTR(Naming Authority PoinTeR) resource record is registered and managed by area code at the initial registration step. ENUM promises convenience and flexibility to both PSTN and IP users, yet there is no evidence how much patience is required when users decide to use ENUM instead of non-ENUM based applications. We have estimated ENUM response time, and proved how to improve performance up to 3 times when resources are managed by the proposed mechanism. The proposition of this thesis favorably influences users and helps to establish the policy for Tier 2 name server management.

• Journal of KIISE:Software and Applications
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• v.30 no.11
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• pp.1080-1091
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• 2003

Recently, the distance education has been rapidly proliferated with the rapid growth of the Internet and high speed networks. There has been relatively much research with regard to online lecture (teaching and studying) tools for the distance education, compared to the virtual laboratory tools (for self-study and experiments). In this paper, we design and implement a web-based simulation tool, named as SimDraw, for the virtual laboratory in the distance education. To apply the web-based simulation technology into the distance education, some requirements should be met; firstly, the user interface of the simulation should be very easy for students. Secondly, the simulation should be very portable to be run on various computer systems of remote students. Finally, the simulation program on remote computers should be very thin so that students can easily install the program onto their computers. To meet these requirements, SimDraw adopts the client/server architecture; the client program contains only model development and animation functions so that no installation of a client program onto student's system is required, and it can be implemented by a Java applet in Web browsers. The server program supports client programs by offering the functions such as remote compiling, model storing, library management, and user management. For the evaluation of SimDraw, we show the simulation process using the example experimentation of the RIP(Routing Information Protocol) Internet routing protocol.

• Journal of KIISE:Computing Practices and Letters
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• v.16 no.1
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• pp.55-59
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• 2010

Currently in a Ubiquitous Sensor Network (USN) research field, supporting mobility is recognized as an important technology. MIPv6 and Network Mobility(NEMO) Basic Support Protocol are standard protocols to support mobility in the Internet. However, if they are applied to USN with no modification, handoff performance decreases due to the size of their binding message. An existing lightweight protocol for NEMO protocol has a compatibility problem of Sequence Num. and does not optimally compress binding messages considering 6LoWPAN network structure and addressing. This paper proposes optimal header compression which supports node-based mobility and network-based mobility. Our optimal compression technique compresses a 32bytes binding update(BU) message and a 12bytes binding ACK(BA) message of MIPv6 into 13bytes and 3bytes, and a 40bytes BU message and a 12bytes BA message of NEMO protocol into 13bytes and 3bytes. The result shows that our protocol compresses 15bytes (NEMO-BU) and 1byte (NEMO-BA) more than the existing protocol and achieves 8.72% handoff performance improvement.