• Journal of Communications and Networks
• /
• 제8권2호
• /
• pp.241-252
• /
• 2006

Traditional service-level agreements (SLAs), defined by average delay or packet loss, often camouflage the instantaneous performance perceived by end-users. We define a set of metrics for service availability to quantify the performance of Internet protocol (IP) backbone networks and capture the impact of routing dynamics on packet forwarding. Given a network topology and its link weights, we propose a novel technique to compute the associated service availability by taking into account transient routing dynamics and operational conditions, such as border gateway protocol (BGP) table size and traffic distributions. Even though there are numerous models for characterizing topologies, none of them provide insights on the expected performance perceived by end customers. Our simulations show that the amount of service disruption experienced by similar networks (i.e., with similar intrinsic properties such as average out-degree or network diameter) could be significantly different, making it imperative to use new metrics for characterizing networks. In the second part of the paper, we derive goodness factors based on service availability viewed from three perspectives: Ingress node (from one node to many destinations), link (traffic traversing a link), and network-wide (across all source-destination pairs). We show how goodness factors can be used in various applications and describe our numerical results.

• 동아시아식생활학회지
• /
• 제6권3호
• /
• pp.355-363
• /
• 1996

Physicochemical properties of marketing and intensive persimmon vinegar were investigated, the results are as following; Total acidity in D, H, S, J, sweet persimmon(SP) and persimmon vinegar were 4.20, 3.03, 2.58, 3.30, 5.92 and 5.81%, respectively, and the value of intensive persimmon(IP) vinegars wre higher than that of others. SP sample was lower than any other vinegar as compared to L value in colors, no sample was lower than H and S vinegar inturbidity and browning. Brix of IP samples were lower than that of other vinegars, there was a little fructose in the all samples. Among the organic acids, galacturonic acid content except acetic acid was the highest, and ascorbic and malic acid were detected a little, Calium content was the highest of minerals in persimmon vinegars, phosphorus was detected a little. Alcohols of 5~6 types were analyzed in each samples, free amino acids of 17~24 dypes were analyzed, D and IP vinegars have more acohols and amino acids, and their contents were higher than the others. Volatile components of 6~9 types were analyzed in each samples, these have more ethanols except acetic acids than other volatile components, and the contents of IP samples were higher than that of marketing persimmon vinegars.

• 한국항행학회논문지
• /
• 제12권6호
• /
• pp.591-597
• /
• 2008

현재 이동통신망의 주요 서비스는 기존의 음성 서비스뿐만 아니라 데이터 서비스의 비중이 점차 늘어가고 있다. 그리고 데이터 서비스는 다양한 미디어가 결합되는 멀티미디어의 형태로 발전하고 있다. 그러나 한재의 네트워크는 멀티미디어 데이터를 기존의 최신형 데이터와 동일하게 처리하여 사용자가 요구하는 QoS를 만족시키지 못한다. 따라서 본 논문에서는 QoS를 제공하는 MPLS기법을 Core망에 적용하여 멀티미디어 데이터의 QoS를 보장할 수 있는 네트워크 구조를 제안한다. 특히 MPLS기법을 Core망에 적용한 경우의 throughput을 시뮬레이션 시간 및 사용자 수의 변화에 따라 비교 분석한다.

• 한국산학기술학회논문지
• /
• 제11권5호
• /
• pp.1640-1645
• /
• 2010

오케스트라 연주에서 각 악기의 연주자가 연주중에 직접 악보를 넘겨야 하는 불편함이 있다. 따라서 본 연구에서는 자동으로 악보를 넘길 수 있는 전자악보 시스템을 Mini-ITX와 LCD Panel을 이용하여 악보대에 일체화 시켜서 제작하였고, 신뢰성 있는 TCP/IP 소켓통신을 사용하여 메시지 및 데이터 전송을 구현하였다. 본 논문에서는 클라이언트에서 자동으로 악보를 표현하는 기능을 구현하였고, 서버 프로그램에서는 악기별로 클라이언트의 개별적 관리가 가능하도록 악보 동기화 기능 및 수동기능을 추가하였다. 그리고, 하나의 악단을 Access파일 하나로 관리 할 수 있기 때문에 악단별 관리가 수월하다. 이와 더불어 TCP/IP 방식의 신뢰성있는 통신을 선택하여, 데이터를 전송하는데 있어서 손실이 생기는 상황을 막아준다.

• 한국컴퓨터정보학회논문지
• /
• 제20권12호
• /
• pp.45-52
• /
• 2015

We propose a hybrid prefix caching scheme to enable high speed IP address lookup. All prefixes loaded in a prefix cache should not be overlapped in address range for correct IP lookup. So, every non-leaf prefix needs to be expanded not so as to be overlapped. The shorter expanded prefix is more preferable because it can cover wider address range just as an single entry in a prefix cache. We exploits advantages of two dynamic prefix expansion techniques, bounded prefix expansion technique and bitmap-based prefix expansion technique. The proposed scheme uses dual bound values whereas just one bound value is used in bounded prefix expansion. Our elaborated technique make the dual bound values be associated with several subtries flexibly using bitmap information, rather than with fixed subtries. We evaluate the performance of the proposed scheme in terms of the average length of the expanded prefixes and cache miss ratio. The experiment results show the proposed scheme has lower cache miss ratio than other previous schemes including both bounded prefix expansion and bitmap-based expansion irrespective of the cache size.

• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2009년도 춘계학술대회 논문집
• /
• pp.848-854
• /
• 2009

Of the rapid development of modem civilization development is one of the IT industry. The Network is the root of the discrete industry. Most of the Protocol is used by LAN and the TCP / IP. Slowly in the railway operation of this Network is being applied. It also used to train and they are operated. The concept of the road, the Network TCP / IP using a non-Star structure of the Main Unit and the Bus Network is designed to structure consists of the Network. This structure is a simplified DATA. Data of complex operations is easy to feel the speed limit is. In addition, all devices must be independent to the operating system with the ability to manage the operation and stability in terms of exactly how the transmission of Data is gonna work pass. And transmission occurs in the middle of the Noise and the device is available to manage the power. Noise in the power of the railway to ensure the efficient transfer of Data is by blocking. Also, by presenting the entire system's operational safety should be guaranteed the safety of the railway.

• 한국식품영양과학회지
• /
• 제24권1호
• /
• pp.160-168
• /
• 1995

Desmutagenicities against 2-amino-1-methyl-6-phenylimidazo[4, 5-b] pyridine(PhIP) and 2-amino-3, 8-dimethylimidazo[4, 5-f]quinoxaline(MelQx) of tea extracts (steamed green tea, roasted green tea, oolong tea and black tea) were investigated. All the fractions obtained from tea extracts showed strong desmutagenic activity against PhIP and MeIQx toward S. typhimurium TA 98 in the presence of the S-9 mix. The crude catechin fraction exhibited the strongest desmutagenic activity. Among these tea extracts, black tea especially exhibited the strongest desmutagenic activity and the activity was 70.9~91.0% against PhIP and 92.2~98.8% against MelQx at a concentration(0.5~1.0mg/plate) for drinking. The activity of authentic catechins of (-)-EGC, (-)-EGCg, (-)-ECg and (-)-EC were 79.5%, 60.2%, 46.1% and 43.5% against PhIP, and were 52.3%, 11.6%, 8.2% and 22.1% against MelQx by addition of 1.0mg/plate, respectively. The desmutagenic activity was supposedly due to the (-)-EGCg, (-)-EGC and (-)-EC in tea polyphenols, and the browning materials. The desmutagenicity was stronger when mutagens were preincubated with S-9 mix after reaciton with black tea extracts than when preincubated with them after reaction with S-9 mix. The desmutagenicity of tea extracts was rather expressed by reacting directly with mutagens than by deactivating the activated forms of mutagens.

• 한국콘텐츠학회:학술대회논문집
• /
• 한국콘텐츠학회 2006년도 춘계 종합학술대회 논문집
• /
• pp.385-387
• /
• 2006

컴퓨터와 통신 기술의 급속한 발전은 사회 전반에 걸쳐 막대한 영향을 미치고 있으며, All-IP망이 도래될 경우 IPv6 환경에서 바이러스와 웜 공격들도 대규모로 증가할 것으로 예상되고 있다. 따라서 IPv6 환경에서 베이지안 기법을 이용한 침해 검출을 제안하였다.

• 융합보안논문지
• /
• 제15권4호
• /
• pp.107-112
• /
• 2015

무선통신기술의 급격한 발달로 인해 상용기술을 접목한 군의 통신 기반체계 또한 무선체계 위주로 변하고 있다. 하지만 군의 통신은 비밀스러운 내용이 많을뿐더러 특히 물리적으로 보안시스템이 불완전한 무선 환경에서는 적의 위협이 더욱더 증가될 것으로 예상된다. 최근 차세대 전술네트워크 통신 시스템이 All IP 기반의 무선체계로 전력화될 예정이다. 본 논문에서는 이러한 무선 환경에서 예상되는 위협요소를 살펴보고 이에 대한 적절한 터널링 기법에 대해 연구해 본다.

• Journal of Communications and Networks
• /
• 제7권2호
• /
• pp.222-230
• /
• 2005

This article presents a field evaluation of an IP-based architecture for heterogeneous environments that has been developed under the aegis of the Moby Dick project, covering UMTS-like (universal mobile telecommunications system) TD-CDMA (time division-code division multiple access) wireless access technology, wireless and wired LANs. The architecture treats all transmission capabilities as basic physical and data-link layers, and replaces all higher-level tasks by IP-based strategies. The Moby Dick architecture incorporates mobile IPv6, fast handovers, AAA-control (authentication, authorisation, accounting), charging and quality of service (QoS) in an integrated framework. The architecture further allows for optimised control on the radio link layer resources. It has been implemented and tested by expert users, and evaluated by real users on field trials with multiple services available.