Young-Joon Won

The Great East Japan Earthquake and Tsunami on March 11, 2011, disrupted a significant part of communications infrastructures both within the country and in connectivity to the rest of the world. Nonetheless, many users, especially in the Tokyo area, reported experiences that voice networks did not work yet the Internet did. At a macro level, the Internet was impressively resilient to the disaster, aside from the areas directly hit by the quake and ensuing tsunami. However, little is known about

SUMMARY Current efforts to classify Internet traffic highlight accuracy. Previous studies have focused on the detection of major applications such as P2P and streaming applications. However, these applications can generate various types of traffic which are often considered as minor and ignorant traffic portions. As network applications become more complex, the price paid for not concentrating on minor traffic classes is in reduction of accuracy and completeness. In this context, we propose a fi

The latest nationwide survey of Pakistan showed that considerable progress has been made toward reducing all child mortality indicators except neonatal mortality. The aim of this study is to compare Pakistan's under-five mortality, neonatal mortality, and postnatal newborn care rates with those of other countries. Neonatal mortality rates and postnatal newborn care rates from the Demographic and Health Surveys (DHSs) of nine low- and middle-income countries (LMIC) from Asia and Africa were analy

Collecting aftermath information after a wide-area disaster is a crucial task in the disaster response that requires important human resources. We propose to assist reconnaissance teams by extracting useful data sent by the users of social networks that experienced the disaster. In particular we consider the photo sharing website Flickr as a source of information that allows one to evaluate the disaster aftermath. We propose a methodology to detect major event occurrences from the behavior of Fl

SUMMARY Industrial control networks (ICNs) and systems support robust communications of devices in process control or manufacturing environments. ICN proprietary protocols are being migrated to Ethernet/IP networks in order to merge various different types of networks into a single common network. ICNs are deployed in mission‐critical operations, which require a maximum level of network stability. Network stability is often described using several categories of network performance quality‐of‐ser

LTE-Advanced (LTE-A) theoretically can provide better network performance than 4G LTE. Mobile network operators around the world are eager to deploy LTE-A to attract more subscribers. However, is it really making difference to the user experience compared to the existing LTE service? To investigate this question, we collected the cellular network performance log from 111 user smartphones on 3G, LTE, and LTE-A. For in-depth analysis, we also asked for privacy information, such as data plan, subsc

To preserve consistent throughput, smartphones are equipped with a network switch feature (handover in heterogeneous networks). Frequent switching is often blamed to be a QoE downgrader in populated areas. In this paper, we measured auto switch occurrences between Wi-Fi and mobile data networks. We deployed an Android monitoring application for 89 participants and collected network status information up to 10 days long. We observed that auto switch occurred on average 2.53 times per hour and RTT

Considering diversified HTTP types, the performance bottleneck of signature-based classification must be resolved. We define a signature model classifying the traffic in multiple dimensions and suggest a hierarchical signature structure to remove signature redundancy and minimize search space. Our experiments on campus traffic demonstrated 1.8 times faster processing speed than the Aho-Corasick matching algorithm in Snort.

Internet traffic classification is an essential step for stable service provision. The payload signature classifier is considered a reliable method for Internet traffic classification but is prohibitively computationally expensive for real-time handling of large amounts of traffic on high-speed networks. In this paper, we describe several design techniques to minimize the search space of traffic classification and improve the processing speed of the payload signature classifier. Our suggestions

Abstract—We present the longitudinal trending analysis of traffic anomalies on a trans-Pacific backbone network over nine years. Throughout our analysis, we try to answer several questions: how frequent do such anomalies appear and how long do they last? Does a set of anomalous hosts occur correspondingly? We answer these by applying the state-ofthe-art anomaly detectors to (un)anonymized packet traces and look into interesting insights from the long-term analysis. The key observations are as fo

LTE-Advanced (LTE-A) theoretically can provide better network performance than 4G LTE. Mobile carriers around the globe are eager to deploy LTE-A to attract more subscribers. However, is it really making difference to the user experience compared to the existing LTE service? To investigate this question, we collected the network performance log from 111 user smartphones on 3G, LTE, and LTE-A. For in-depth analysis, we also asked for privacy information, such as data plan, subscribed network, mon

This paper provides a temporal cellular and WiFi networks analysis from a nationwide crowdsourcing measurement study. Our dataset consists of 2.98M user-initiated quality tests on 3G/LTE/WiFi involving 157K mobile devices from Nov. 2012 to July 2016 (187 weeks) in South Korea. Our analysis explains changes in QoS from the user perspective, not Mobile Network Operators (MNO). We revealed that WiFi shows twice higher compounded quarterly growth rate for download throughput against LTE. Yet, LTE an

To preserve consistent throughput, smartphones are equipped with a network switch feature (handover in heterogeneous networks). Frequent switching is often blamed to be a QoE downgrader in populated areas. In this paper, we measured auto switch occurrences between Wi-Fi and mobile data networks. We deployed an Android monitoring application for 89 participants and collected network status information up to 10 days long. We observed that auto switch occurred on average 2.53 times per hour and RTT

Application-level traffic classification is an essential requirement for stable network operation and resource management. The payload signature-based classifier is considered a reliable method for Internet traffic classification. However, with this system, processing speeds are slower when high volumes of traffic are being classified in high-speed networks in real time. In this paper, we propose a method for server IP-port pair cachebased traffic classification, with the aim of increasing the p