• 대한공업교육학회지
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• v.33 no.2
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• pp.248-258
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• 2008

Current Internet uses HTTP (Hyper Text Transfer Protocol) as an application layer protocol and TCP (Transmission Control Protocol) as a transport layer protocol to provide web service. SCTP (Stream Control Transmission Protocol) is a recently proposed transport protocol with very similar congestion control mechanisms as TCP, except the initial congestion window during the slow start phase. In this paper, we present a mathematical model of object transfer latency during the slow start phase for HTTP over SCTP and compare with the latency of HTTP over TCP. Validation of the model using experimental result shows that the mean object transfer latency for HTTP over SCTP during the slow start phase is less than that for HTTP over TCP by 11%.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.11B
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• pp.1277-1284
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• 2011

Today, many applications use 80 port, which is a basic port number of HTTP protocol, to avoid a blocking of firewall. HTTP protocol is used in not only Web browsing but also many applications such as the search of P2P programs, update of softwares and advertisement transfer of nateon messenger. As HTTP traffics are increasing and various applications transfer data through HTTP protocol, it is essential to identify which applications use HTTP and how they use the HTTP protocol. In order to prevent a specific application in the firewall, not the protocol-level, but the application-level traffic classification is necessary. This paper presents a method to classify HTTP traffics based on applications of the client-side and group the applications based on providing services. We developed an application-level HTTP traffic classification system and verified the method by applying the system to a small part of the campus network.

• Journal of the Korea Computer Industry Society
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• v.6 no.2
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• pp.305-316
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• 2005

A heterogeneous webserver such as an HTTP server should be able to currently deal with numerous users. To the end, it is inevitable to formally analyze web traffics as well as a webserver itself. In particular, as most systems adopt HTTP 1.1 protocol instead of HTTP 1.0 protocol, it is more difficult to represent the system as a simple analytic mode. In addition, since most of previous models missed the detailed processes of the server, it is unsuitable for the current server based on HTTP 1.1 to tune itself with its own system parameters. On the basis of HTTP 1.1 Protocol supporting persistent connections, we thus present an analytical end-to-end tandem queueing model considering specific hardware configurations inside the webserver, which ultimately covers from accepting the customer requests to completing the services.

• The KIPS Transactions:PartC
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• v.9C no.6
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• pp.865-874
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• 2002

HTTP (HyperText Transfer Protocol) is a transfer protocol used by the World Wide Web distributed hypermedia system to retrieve the objects. Because HTTP is a connection oriented protocol, it uses TCP (Transmission control Protocol) as a transport layer. But it is known that HTTP interacts with TCP badly. it is discussed about factors affecting the performance or HTTP over TCP, the transaction time obtained by the per-transaction TCP connections for HTTP access and the TCP slow-start overheads, and the transaction time for T-TCP (Transaction TCP) which is one or methods improving the performance or HTTP over TCP. Average waiting time and average turnaround time are important parameters to satisfy QoS (Quality of Service) of end users. Formulas for calculating two parameters are derived. Such formulas can be used for the environment in which each TCP or T-TCP transaction time is same or different. Some experiments and computational experiences indicate that the proposed formulas are well acted, can be applied to the environment which the extension of bandwidth is necessary, and time characteristics of T-TCP are superior to that of TCP. Also, the load distribution method of web server based on the combination of bandwidths is discussed to reduce average waiting time and average turnaround time.

• KIPS Transactions on Computer and Communication Systems
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• v.10 no.5
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• pp.137-144
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• 2021

The IETF has recently been standardizing the QUIC protocol for HTTP/3 services. It is noted that HTTP/3 uses QUIC as the underlying protocol, whereas HTTP/1.1 and HTTP/2 are based on TCP. Differently from TCP, the QUIC uses 0-RTT or 1-RTT transmissions to reduce the connection establishment delays of TCP and SCTP. Moreover, to solve the head-of-line blocking problem, QUIC uses the multi-streaming feature. In addition, QUIC provides various features, including the connection migration, and it is available at the Chrome browser. In this paper, we analyze the performance of QUIC for HTTP-based web and streaming services by comparing with the existing TCP and Streaming Control Transmission Protocol (SCTP) in the network environments with different link delays and packet error rates. From the experimental results, we can see that QUIC provides better throughputs than TCP and SCTP, and the gaps of performances get larger, as the link delays and packet error rates increase.

• Journal of KIISE:Information Networking
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• v.30 no.3
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• pp.377-386
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• 2003

In this paper, we present an application layer protocol to support secure wireless Internet services, called Application Layer Security(ALS). The drawbacks of the two traditional approaches to secure wireless applications motivated the development of ALS. One is that in the conventional application-specific security protocol such as Secure HyperText Transfer Protocol(S-HTTP), security mechanism is included in the application itself. This gives a disadvantage that the security services are available only to that particular application. The other is that a separate protocol layer is inserted between the application and transport layers, as in the Secure Sockets Layer(SSL)/Transport Layer Security(TLS). In this case, all channel data are encrypted regardless of the specific application's requirements, resulting in much waste of network resources. To overcome these problems, ALS is proposed to be implemented on top of HTTP so that it is independent of the various transport layer protocols, and provides a common security interface with security applications so that it greatly improves the portability of security applications. In addition, since ALS takes advantages of well-known TLS mechanism, it eliminates the danger of malicious attack and provides applications with various security services such as authentication, confidentiality integrity and digital signature, and partial encryption. We conclude this paper with an example of applying ALS to the solution of end-to-end security in a present commercial wireless protocol stack, Wireless Application Protocol.

• Journal of KIISE
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• v.41 no.10
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• pp.824-831
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• 2014

HTTP (Hypertext Transfer Protocol) Adaptive Streaming is gaining attention because it changes bitrates to adapt changing network conditions. Since HAS (HTTP Adaptive Streaming) client downloads the video data based on TCP (Transmission Control Protocol), it estimates incorrectly the available bandwidth and leads to an unnecessary video quality change in long-delay networks. In this paper, we propose a buffer-based quality control scheme in order to improve the service quality and smooth playback in the HAS. The proposed scheme estimates accurately the available bandwidth based on a modified streaming model that considers network delay. It also calculates the sustainability of the video quality to prevent an unnecessary quality change and determines the inter-request time on the basis of the buffer status. Through the simulation, we prove that our scheme improves the QoS (Quality of Service) of the HAS service and controls the video quality smoothly in long-delay networks.

• The Journal of Korean Association of Computer Education
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• v.6 no.2
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• pp.41-51
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• 2003

In the distance education systems, there are limited things while performing educational activities because there are to be problems in structural features of the Web. HTTP, a connection-less protocol, performs requests of client, however, does not hold on the status. Thus, by features of the Web, it is difficult to hold on the connection of learners and trace information asked by learners. Moreover, these problems make impossible not only a learner's connection continuity but also on-line interaction among the learners in the distance education. This thesis developed CHTP, an connection-based hypertext transfer protocol, based on HTTP and a new platform of distance education in order to track activities of learners. The developed web extension platform will make it easy to build up system for being helpful in a distance education because this thesis proposes a standardized way in the protocol.

• The KIPS Transactions:PartC
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• v.9C no.4
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• pp.605-614
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• 2002

Amount of the web traffic web server handles are explosively increasing, which requires that the performance of the web server should be improved for the various web services. Although the analysis for the HTTP traffic with the proper tuning for the web server is essential, the research relevant to the subject are insignificant. In particular, although most of applications are implemented over HTTP 1.1 protocol, the researches mostly deal with the performance evaluation of the HTTP 1.0 protocol. Consequently, the modeling approach and the performance evaluation over HTTP 1.1 protocol have not been well formed. Therefore, basing on the HTTP 1.1 protocol supporting persistent connection, we present an analytical end-to-end tandem queueing model for web server to consider the specific hardware configuration inside web server beginning at accepting the user request until completing the service. we compare various performances between HTTP 1.0 and HTTP 1.1 under the overloading condition, and then analyze the characteristics of the HTTP traffic that include file size requested to web server, the OFF time between file transfers, the frequency of requests, and the temporal locality of requests. Presented model is verified through the comparing the server throughput according to varying requests rate with the real web server. Thereafter, we analyze the performance evaluation of the web server, according to the interrelation between TCP Listen queue size, the number of HTTP threads and the size of the network buffers.

• Proceedings of the Korean Society of Computer Information Conference
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• 2020.07a
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• pp.77-80
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• 2020

In this paper, we analyze and compare the performance of different publish and subscribe protocols in the real application environment. This paper provides a horizontal comparison of current publish/subscribe protocols in terms of security, throughput, and delay performance. Thanks to the use of lightweight frameworks, the MQTT protocol has demonstrated excellent performance in terms of delay performance. However, the AMQP protocol has more advantages in security and throughput. Although the REST/HTTP protocol has the worst delay performance, it is excellent in terms of compatibility because it is based on the HTTP protocol.