• Journal of IKEEE
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• v.7 no.2 s.13
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• pp.260-264
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• 2003

Among many factors to affect the network performance, this paper analyses how the buffer size of NIC(Network Interface Card) can affect web server and LAN(Local Area Network). We use the ns-2 which is defacto network simulation tool to observe the changes in drop rate, throughput, RTT(Round Trip Time), effective throughput depending on varying buffer sizes. And we analyse the effect of NIC buffer size on the web traffic in Ethernet.

• Proceedings of the Korea Information Processing Society Conference
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• 2001.10a
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• pp.461-464
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• 2001

소프트웨어 위기를 극복하기 위해 재사용성, 유지보수성, 적시성 관점에서 컴포넌트 기반 방법론이 크게 각광받고 있다. 또한 기존의 코드를 이용하여 컴포넌트를 만드는 방법, 컴포넌트를 이용하여 새로운 컴포넌트를 만드는 방법 등 여러 컴포넌트 기술이 개발되고 있다. 본 논문에서는 컴포넌트의 개발 시간을 단축하기 위한 컴포넌트 생성 지원 도구 개발에 대해 간단히 설명한 후 설계와 구현을 동시에 할 수 있는 컴포넌트 클래스 다이어그램에 대해 기술한다. 설계와 구현을 동시에 지원함으로서 개발기간을 크게 단축할 수 있고 설계와 구현의 동일성을 보장한다. 또한 컴포넌트 클래스 다이어그램은 EJB 컴포넌트에 전개까지 지원한다.

• 한국IT서비스학회:학술대회논문집
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• 2006.05a
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• pp.241-248
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• 2006

네트워크 거리 (Network distance : 일반적으로 ping이나 traceroute 등으로 측정 가능한 round trip time 등 네트워크 상에서 패킷 전송 시간) 추정 기법은 인터넷상의 많은 응용프로그램들에서 유용하게 사용된다. 예를 들면 다수의 서버를 인터넷상에 설치하고자 하는 경우 사용자들 간의 네트워크 거리를 알고 있다면 서버와 사용자간의 왕복 전송 시간 (Round Trip Time)등을 최소화할 수 있도록 서버를 분산하여 설치하는 구성을 도출해 낼 수 있을 것이다. Peer to Peer 응용 프로그램들에서도 이 네트워크 거리 정보는 매우 유용하다. 기존에 존재하는 추정 기법들은 대부분 유클리드 공간 좌표 기반 기법들로서 유클리드 좌표 상의 거리가 실제 네트워크 거리와 유사하도록 유클리드 공간 좌표를 지정한다. 그러나 이런 방법들의 문제점은 인터넷 상의 네트워크 거리가 삼각 부등식을 만족하지 않는 경우가 존재하는 등 유클리드 공간의 기본적인 가정을 만족하지 못한다는데 있다. 이런 문제점 때문에 새로운 모델이 필요하고, 이 논문에서는 가상 토폴로지(Virtual Topology) 모델과 지역 조정 항 (Local Adjustment Term) 모델을 제시하고, 기본적인 성능 분석을 시도하였다.

• Journal of KIISE:Information Networking
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• v.31 no.1
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• pp.91-100
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• 2004

This paper presents a receiver-driven TCP flow control mechanism, which is adaptive to the wireless condition, for memory constrained mobile receiver. A receiver-driven TCP flow control is, in general, achieved by adjusting the size of advertised window at the receiver. The proposed method constantly measures at the receiver both the available wireless bandwidth and the packet round-trip time. Depending on the measured values, the receiver adjusts appropriately the size of advertised window. Constrained by the adjusted window which reflects the current state of the wireless network, the sender achieves an improved TCP throughput as well as the reduced round-trip packet delay. Its implementation only affects the protocol stack at the receiver and hence neither the sender nor the router are required to be modified. The mechanism has been implemented in real environments. The experimental results show that in CDMA2000 1x networks the TCP throughput of the proposed method has improved about 5 times over the conventional method when the receiver's buffer size is limited to 2896 bytes. Also, with 64Kbytes of buffer site, the packet round-trip time of the proposed method has been reduced in half, compared the case with the conventional method.

• Journal of KIISE:Information Networking
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• v.37 no.1
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• pp.27-34
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• 2010

In this paper, we examine a long-range dependence in an active measurement of a network traffic which has been a well known characteristic from analyses of a passive network traffic measurement. To this end, we utilize RTT(Round Trip Time), which is a typical active measurement measured by PingER project, and perform a relevant analysis to a time series of both RTT and its volatilities. The RTT time series exhibits a long-range dependence or a 1/f noise. The volatilities, defined as a higher-order variation, follow a log-normal distribution. Furthermore, volatilities show a long-range dependence in relatively short time intervals, and a long-range dependence and/or 1/f noise in long time intervals. From this study, we find that the long-range dependence is a characteristic of not only a passive traffic measurement but also an active measurement of network traffic such as RTT. From these findings, we can infer that the long-range dependence is a characteristic of network traffic independent of a type of measurements. In particular, an active measurement exhibits a 1/f noise which cannot be usually found in a passive measurement.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37B no.11
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• pp.965-974
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• 2012

As the use of smart devices has become popular, the number of smart devices connected to network has increased and the amount of traffic from them has grown rapidly. The management of mobile traffic and IP address for smart devices in an enterprise network is crucial problem for efficient operation of network. The information about connection type of a terminal host to the network will be very useful for stable and efficient management of an enterprise network. Also, this information might be used to identify NAT device. In this paper, we propose a methodology to identify the connection type of a terminal host using RTT (Round-Trip-Time) value extracted from captured packets. We prove the feasibility of our proposed method in a target campus network.

• Journal of the Korean Society for Railway
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• v.16 no.6
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• pp.482-491
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• 2013

Current metro tickets are categorized into transportation cards and monthly season tickets, which offer limited consumer choices. A metro fare system should be introduced based on the diversity of customer demand. Thus, this study's objective is that the metro fare system in Korea should be efficiently operated by analyzing a variety of metro fare systems used in major cities of other countries. In addition, this study proposed the following metro fare systems, one day pass, which is generally used in other countries in a bid to promote public transportation, reduce costs, and increase revenue. A commuting ticket system to increase the demand from cars to subways, and special discounts & a round-trip ticket system for round-trip travelers in case that demand is low was compared with the high supply on the Gyeongchun-line.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.6
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• pp.707-713
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• 2016

In the IEEE 802.11 Wireless LAN environment, the common Access Point (AP) selection of the existing terminal is based on signal strength. However, the signal strength-based AP selection method does not ensure an optimal data rate. Recently, several AP selection methods to solve this problem have been suggested. However, when we select AP, these have a latency problem and don't consider dense environments of AP. In this paper, we confirm the problem of the conventional AP selection about the signal strength and the throughput through the actual measurement, and propose algorithm that selects AP by scoring link speed and wireless round trip time to compensate the problem. Furthermore, the proposed AP selection algorithm through the actual experiment proves the improved performance as compared with the existing methods.

• The Journal of the Convergence on Culture Technology
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• v.9 no.5
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• pp.159-165
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• 2023

This study was limited to the underwater search part among water accidents on the inland water surface, and analyzed five underwater search methods and lifesaving time at 5m underwater. The subjects of the experiment were 10 people. The semi-circle search took the longest with 259 seconds, and the modified round-trip search took 78.60 seconds, showing a significant difference with an average of 180.04 seconds. Subjects B and D showed similar values, with average underwater search times of 199 seconds and 202 seconds, respectively. Subject C showed a significantly higher average underwater search time of 209 seconds. The reason seems to be from increased anxiety and excessive tension due to poor underwater watch. Subject A showed a significantly lower underwater search time of 187 seconds. The reason seems to be the result of E's experience being the most among the test subjects and his rich diving experience in the Han River with poor visibility. As for convenience, semicircle search showed a low score of 6~7, and modified reciprocal search showed a high score of 8~9. The most suitable rescue method as an underwater search method in the Han River where visibility is poor is determined to be a modified round-trip search method.

• Journal of the Institute of Convergence Signal Processing
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• v.24 no.2
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• pp.112-118
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• 2023

Internet of Things(IoT) technology is developing to a stage where the Internet and objects are connected and objects themselves analyze and judge data to interconnect the real world and the virtual world in real time. This technology consists of sensors, actuators, devices, and networks, and it is being applied in various fields. As the number of IoT devices and applications increases, data traffic also increases. In this paper, a messaging system is designed and implemented in order to analyze the performance between an IoT device and MQTT broker. The experimental was performed to measure MQTT-based round-trip time and message transmission time between the IoT device and the broker. The result shows that there is no packet loss, and propagation delay affects round-trip time.