• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제12권11호
• /
• pp.5179-5202
• /
• 2018

Transmission Control Protocol (TCP) is the most widely used protocol in the cloud data centers today. However, cloud data centers using TCP experience many issues as TCP was designed based on the assumption that it would primarily be used in Wide Area Networks (WANs). One of the major issues with TCP in the cloud data centers is the Incast issue. This issue arises because of the many-to-one communication pattern that commonly exists in the modern cloud data centers. In many-to-one communication pattern, multiple senders simultaneously send data to a single receiver. This causes packet loss at the switch buffer which results in TCP throughput collapse that leads to high Flow Completion Time (FCT). Recently, Software-Defined Networking (SDN) has been used by many researchers to mitigate the Incast issue. In this paper, a detailed survey of various SDN based solutions to the Incast issue is carried out. In this survey, various SDN based solutions are classified into four categories i.e. TCP Receive Window based solutions, Tuning TCP Parameters based solutions, Quick Recovery based solutions and Application Layer based solutions. All the solutions are critically evaluated in terms of their principles, advantages, and shortcomings. Another important feature of this survey is to compare various SDN based solutions with respect to different performance metrics e.g. maximum number of concurrent senders supported, calculation of delay at the controller etc. These performance metrics are important for deployment of any SDN based solution in modern cloud data centers. In addition, future research directions are also discussed in this survey that can be explored to design and develop better SDN based solutions to the Incast issue.

• 한국IT서비스학회지
• /
• 제12권1호
• /
• pp.1-14
• /
• 2013

The government has implemented operating the bus information terminal (hereinafter, 'BIT') to use by building it at a major bus station to solve the problem of traffic congestion. Busan Metropolitan City has been continuously expanding the installation of 'BIT' since 2003. However, there are few research on the factor to use and satisfaction survey on 'BIT' from the perspective of the users. This study, in an effort to inquire into the 'BIT' utilization factor and its vitalization plan, conducted a face to face survey of 172 citizens who had the experience in the 'BIT'. The result of the data analysis showed that usability, convenience, and availability were the critical factors for a BIT use. In addition, the general intention to use 'BIT' was found to be very high as much as 90.7%. The contributions of this study are as follows. The academic contributions is that it proved the relationship between usability, convenience and the intention to use suggested by the information technology acceptance model is supported even in case of 'BIT.' For the practitioners this study provides ground data for a local government to make a plan of a BIT extension.

• 한국동물위생학회지
• /
• 제28권1호
• /
• pp.31-38
• /
• 2005

To examine the prevalence and type of lesions in urinary bladder of Korean cattle, a random sampling survey was performed at a Jeonju abattoir in September 2000 and January 2001. Collected urinary bladder were examined grossly and histopathologically and the patterns of disease were investigated with season and sex. Of 735 cattle(99 bulls and 246 cows in September and 141 bulls, 3 steers, and 246 cows in January) surveyed, $26.3\%$ cattle with evident lesions were found. The most common gross finding was urolithiasis of urinary bladder($23.8\%$). Other lesions included hemorrhage($5.9\%$), congestion($4.1\%$), hematuria($2.7\%$), pyuria($0.7\%$), hyperplasia($0.5\%$). Urinary calculi collected in this study contained 80 to $90\%$ of calcium oxalate and 10 to $20\%$ of struvite, with or without $20\%$ of cystine and $10\%$ of uric acid. This study on urolithiasis and pathology of urinary bladder of slaughtered Korean cattle revealed subclinical aspects and management problem in Korean beef product.

• 한국시뮬레이션학회논문지
• /
• 제11권4호
• /
• pp.43-55
• /
• 2002

Vessel traffic safety management means the managerial technical measures for improving the marine traffic safety in general terms. The main flow of vessel traffic safety management is that: 1) Traffic Survey, 2) Replay by Marine Traffic Flow Simulation, 3) Quantitative Assessment, 4) Policy Alternatives, 5) Prediction·Verification. In the management of vessel traffic safety, it is most important to establish assessment models that can numerically estimate the current safety level and quantitatively predict the correlation between the measures to be taken and the improvement of safety and the reduction of ship handling difficulties imposed on mariners. In this paper, the replay model for traffic flow simulation was made using marine traffic survey data, and the present traffic situation became replay in the computer. An attempt was made to rate the current safety of ports and waterways by applying the Environmental Stress model. And, as a countermeasure for traffic management, by taking of, the promotion of total traffic congestion in early morning rush hour, the correlation between traffic control rate and the reduction in ship handling difficulties imposed on mariners was predicted quantitatively.

• 대한수의학회지
• /
• 제40권3호
• /
• pp.611-625
• /
• 2000

For the improvement of quality control of laboratory mouse, we investigated the environmental condition, histopathological findings and serological test using ELISA to mouse hepatitis virus(MHV), Mycoplasma pulmonis(MP), Clostridium piliforme(TZ) and Sendai virus (HVJ) of ICR, C57BL/6, CBA and C3H/He mice that were supplied from conventional laboratory animal facility. 1. The ammonia concentration of facility was below the recommended concentration, 15ppm, by the KNIH, and the room temperature($21{\sim}23^{\circ}C$) and relative humidity(40~60%) was optimum range recommend by the Ministry of Health and Welfare, respectively. 2. The incidence rate of inapparent disease was 86.6% and the major findings in the liver were vacuolar degeneration with nucleic pleomorphism. The lung was shown the thickening of alveolar wall and interstitial pneumonia with congestion. The kidney and spleen were observed the mild congestion and extramedullary hematopoiesis, respectively. 3. The positive reaction rates against MHV and MP in serological test was 97.9% and 37.5%, respectively but HVJ and TZ were negative. These results suggest that laboratory mice could be infected with MHV and MP under conventional environments. Therefore we recommend to select thoroughly inapparent infected mice and to convert conventional system into SPF facility as soon as possible.

• 한국환경보건학회지
• /
• 제46권2호
• /
• pp.204-213
• /
• 2020

Objective: This study is aimed at investigating indoor air quality on public transportation (subway, train, and bus) according to changes in season and time. Methods: We evaluated TVOC and HCHO on public transportation based on the un-controlled parameters of the Ministry of Environment. We also measured temperature and humidity since they affect the concentration of TVOC and HCHO. For public transportation classification, subway lines were classified into Lines 1 to 4. Additionally, trains were classified as ITX and KTX. Results: When comparing summer and winter on public transportation, the concentrations of TVOC and HCHO did not show any particular tendency. However, the concentrations of TVOC and HCHO during traffic congestion was higher than levels during times of non-congestion on most public transportation. In summer and winter, the measurement results for temperature and humidity showed a normal range, so temperature and humidity did not affect the concentrations of TVOC and HCHO. In the case of TVOC, TVOC concentrations on new trains were found to be relatively higher than on older ones, but there was no statistically correlation. Conclusions: A survey was conducted on the indoor air quality on public transportation. This study also analyzed data based on TVOC and HCHO for designing policies and managing indoor air quality.

• 한국ITS학회 논문지
• /
• 제1권1호
• /
• pp.33-40
• /
• 2002

서울시 도심에 구축된 남산1호터널 교통정보시스템은 혼잡통행료 징수구간인 남산1호터널을 통과하는 운전자들에게 예측하기 어렵게 빈번히 발생하는 교통정체에 관한 정보를 사전에 제공해주기 위해서 2000년 12월 21일부터 운영중인 국내 최초의 도심부 터널에 대한 첨단교통정보시스템이다. 본 연구는 남산1호터널 교통정보시스템에 대한 모니터링을 통해 도시부 교통정보시스템의 운영효과를 분석한다. 모니터링 결과 남산1호터널 교통정보시스템 운영후, 터널부를 중심으로한 축방향 교통여건은 상당히 호전되었으며, 우회로에 해당되는 주변도로는 이용차량의 증가에도 불구하고 이론적으로 있을 수 있는 과도한 경로전환에 의한 악영향은 별반 나타나지 않았다. 또한, 교통정보시스템에 대한 운전자 만족도 조사결과 높은 지지도를 받고 있어 매우 작은 시스템임에도 불구하고 교통서비스 개선에 크게 기여하고 있는 것으로 분석되었다.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제6권1호
• /
• pp.178-202
• /
• 2012

In this paper, we first survey cross-layer architectures for Wireless Sensor Networks (WSNs) and Wireless Multimedia Sensor Networks (WMSNs). Afterwards, we propose a novel cross-layer architecture for QoS provisioning in clustered and multi-hop based WMSNs. The proposed architecture provides support for multiple network-based applications on a single sensor node. For supporting multiple applications on a single node, an area in memory is reserved where each application can store its network protocols settings. Furthermore, the proposed cross-layer architecture supports heterogeneous flows by classifying WMSN traffic into six traffic classes. The architecture incorporates a service differentiation module for QoS provisioning in WMSNs. The service differentiation module defines the forwarding behavior corresponding to each traffic class. The forwarding behavior is primarily determined by the priority of the traffic class, moreover the service differentiation module allocates bandwidth to each traffic class with goals to maximize network utilization and avoid starvation of low priority flows. The proposal incorporates the congestion detection and control algorithm. Upon detection of congestion, the congested node makes an estimate of the data rate that should be used by the node itself and its one-hop away upstream nodes. While estimating the data rate, the congested node considers the characteristics of different traffic classes along with their total bandwidth usage. The architecture uses a shared database to enable cross-layer interactions. Application's network protocol settings and the interaction with the shared database is done through a cross-layer optimization middleware.

• 대한전자공학회:학술대회논문집
• /
• 대한전자공학회 1998년도 추계종합학술대회 논문집
• /
• pp.297-300
• /
• 1998

The Phone Voting service allows subscribers to propose a voting through a telephone, and enables them to survey public opinion using telephone network. The demand on this service is growing faster and demands will be increased much more. It makes the bust traffic at the Toll SSP system on Intelligent Network because of the temporary bust traffic congestion on the Toll SSP compared to the normal call traffic. This paper will show what the problems and the causes are, and how we can solve them. The solution to these problems is an implementation of the SSP function on the Local Excange for the PV service.

• 한국항해항만학회:학술대회논문집
• /
• 한국항해항만학회 2012년도 춘계학술대회
• /
• pp.52-54
• /
• 2012

Saigon-Vungtau fairway is the main and the most important fairway of the major economic areas: Ho Chi Minh City, Dong Nai Province and Ba Ria-Vung Tau Province in Vietnam. In last 5 years, 80% of accidents happened on the fairway were caused by collision and contact/impact. This presentation study on marine traffic investigation in the adjacent of the fairway to find out problems related to marine traffic for improving Marine Traffic Safety Management in this area.