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Enhanced ARP: preventing ARP poisoning-based man-in-the-middle attacks
Seung Yeob Nam,Dongwon Kim,Jeongeun Kim IEEE 2010 IEEE communications letters Vol.14 No.2
<P>In this letter, an enhanced version of Address Resolution Protocol (ARP) is proposed to prevent ARP poisoning-based Man-in-the-Middle (MITM) attacks. The proposed mechanism is based on the following concept. When a node knows the correct Media Access Control (MAC) address for a given IP address, if it retains the IP/MAC address mapping while that machine is alive, then MITM attack is impossible for that IP address. In order to prevent MITM attacks even for a new IP address, a voting-based resolution mechanism is proposed. The proposed scheme is backward compatible with existing ARP and incrementally deployable.</P>
Estimation of available bandwidth for an M/G/1 queueing system
Nam, Seung Yeob,Kim, Sunggon,Sung, Dan Keun Elsevier 2009 Applied mathematical modelling Vol.33 No.8
<P><B>Abstract</B></P><P>This paper is concerned with estimating the available bandwidth, the residual processing capacity, of a single-server queueing system whose service rate and the input traffic load are not known in advance. We analyze the minimal-backlogging method which has been proposed to estimate the available bandwidth by sending probing packets. We show that an M/G/1 queueing system probed by the minimal-backlogging method is stable. A consistent estimator of the inverse of available bandwidth is proposed based on the sojourn times of the probing packets. We also estimate the available bandwidth of a local server which is connected to the probing node with non-zero delay as an application of the theory developed for a single-server queue. We evaluate the accuracy of the proposed available bandwidth estimation scheme by simulation.</P>
Defending HTTP Web Servers against DDoS Attacks through Busy Period-based Attack Flow Detection
( Seung Yeob Nam ),( Sirojiddin Djuraev ) 한국인터넷정보학회 2014 KSII Transactions on Internet and Information Syst Vol.8 No.7
We propose a new Distributed Denial of Service (DDoS) defense mechanism that protects http web servers from application-level DDoS attacks based on the two methodologies: whitelist-based admission control and busy period-based attack flow detection. The attack flow detection mechanism detects attach flows based on the symptom or stress at the server, since it is getting more difficult to identify bad flows only based on the incoming traffic patterns. The stress is measured by the time interval during which a given client makes the server busy, referred to as a client-induced server busy period (CSBP). We also need to protect the servers from a sudden surge of attack flows even before the malicious flows are identified by the attack flow detection mechanism. Thus, we use whitelist-based admission control mechanism additionally to control the load on the servers. We evaluate the performance of the proposed scheme via simulation and experiment. The simulation results show that our defense system can mitigate DDoS attacks effectively even under a large number of attack flows, on the order of thousands, and the experiment results show that our defense system deployed on a linux machine is sufficiently lightweight to handle packets arriving at a rate close to the link rate.
Synthesis and Rust Preventing Properties of Dodecyl Succinate Derivatives Containing Triazole Groups
Baek, Seung-Yeob,Kim, Young-Wun,Yoo, Seung-Hyun,Chung, Keunwoo,Kim, Nam-Kyun,Kim, Joon-Seop American Chemical Society 2012 INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH - Vol.51 No.28
<P>Green corrosion inhibitors, <I>n</I>-dodecyl succinate derivatives containing one (HSE) or two triazole groups (DSE), were prepared by three step reactions, that is, nucleophilic substitution reaction, click coupling reaction, and esterification reaction. The characterization results obtained from <SUP>1</SUP>H NMR, FT-IR, and elemental analysis indicated that the succinate derivatives were synthesized successfully. The rust preventing properties of the final products were also investigated using both ASTM D665 and weight loss methods. It was found that the strength of rust-preventing property due to the presence of succinate derivatives in paraffin oil was largely determined by the concentration of alkyl chains, not by their length or by the types of functional groups.</P>
Development of an articulated mine-detecting manipulator system for mobile robots
Yu, Seung-Nam,Choi, Chang-Hwan,Lee, Seung-Yeol,Lee, Jeong-Yeob,Han, Chang-Soo 대한기계학회 2011 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.25 No.4
This paper presents a servo motor selection technique for a mobile mine detection system which is operated in the field condition. As a first step, mine detection sensor should follow the earth profile while maintaining a constant distance to the earth surface. In order to acquire a reasonable manipulator trajectory and its required torque, a kind of modeling technique is devised to remove the unwanted fluctuations in the earth data. Then, Straete et al.'s normalization method is adopted and is improved to select the adequate actuator for each joint of manipulator. The improvements are as follows: First, an equivalent output power lines are plotted at the same load curve, which gives another selection criterion. Second, a temperature based criterion is proposed for the continuous limit, which estimates the steady state winding temperature of a motor, and can be used to determine a suitable motor and gear ratio. This formulation gives not only the selection of a motor and gear ratio, but also gives the estimated operating temperature. Finally, realized system is verified through the basic performance test.
숙신산 알킬 하프-아마이드 유도체의 합성 및 해수에 대한 방청성능
백승엽(Seung-Yeob Baek),김영운(Young-Wun Kim),정근우(Keun-Wo Chung),유승현(Seung-Hyun Yoo),김남균(Nam-Kyun Kim) 한국청정기술학회 2011 청정기술 Vol.17 No.4
아마이드 유도체는 방청성능 및 윤활성능이 우수하여 금속가공유 및 유압작동유등의 첨가제로 많이 사용되고 있다. 본 연구에서는 광유계 윤활기유의 방청제로 사용하기 위하여 알킬 무수 숙신산과 여러 가지 아민과의 링개환 반응을 행하여 카르복실 그룹과 아마이드 그룹을 동시에 포함하는 숙신산 알킬 하프-아마이드 유도체들을 97% 이상의 수율로 합성하였으며 합성구조에 따라 1 중량% 농도범위에서 광유계 오일에 용해되었다. 합성 유도체의 구조는 <SUP>1</SUP>H-NMR 및 FT-IR 스펙트럼으로 행하였으며 GC 크로마토그램을 통하여 화합물의 순도를 확인하였다. 또한, 합성 유도체의 해수에 대한 방청성능을 ASTMD 665 표준방법과 무게 중량법으로 평가한 결과, 합성 유도체의 농도가 증가하고 알킬기의 사슬이 짧고 2차 아민으로 합성한 숙신산 알킬 하프-아마이드의 방청성능이 1차 아민으로 합성한 유도체보다 상대적으로 방청성능이 우수하였다. 무게 중량법으로 평가한 방청효율% (IE%)는 알킬기의 사슬이 짧을수록 우수한 방청효율을 나타내었으며 구조에 따라 방청효율에 차이를 나타내었다. 40 ppm 농도를 첨가한 오일의 IE%는 최고 93% 이상이었다. 또한, 발청속도(Corrosion Rate, CR)는 알킬기의 사슬이 짧을수록 낮은 값을 나타내어 합성 유도체 40 ppm 농도를 첨가한 오일의 CR 값은 최고 0.5 mm/year 이하로 나타났다. Several amide derivatives have been used as additives for base oil of metal working fluids and pressure working oils. In this paper, a series of succinic acid alkyl half-amide derivatives were synthesized as over 97% yields by ring-opening reaction of succinic anhydride and several amines and were soluble in 100 N base oil within 1 wt% concentration. The structures of the synthesized amides were confirmed by <SUP>1</SUP>H-NMR, FT-IR spectrum and GC analysis. Anti-corrosion properties of the amides in sea water were evaluated through ASTM D665 method and weight loss method. As the results of anti-corrosion properties, the properties of the amides with shorter alkyl chain and high concentration showed better performance than those with longer alkyl chain and low concentration. Also, the dialkyl amides showed better anti-corrosion properties than those of the monoalkyl amides. Inhibition efficiency% (IE%) was over 93% in the concentration of 40 ppm and corrosion rate (CR) was below 0.5 mm/year in the same concentration.
Localization of Access Points Based on Signal Strength Measured by a Mobile User Node
IEEE 2014 IEEE communications letters Vol.18 No.8
<P>The issue of locating access points (APs) in a building is investigated in detail in this paper. The signal strength of beacon frames from a selected AP is measured at multiple positions, and the location of the selected AP is estimated based on the distance information inferred from the measured signal strength and a modified version of the Hata-Okumara model. A strategy is proposed to select three measurement points to improve localization accuracy for a selected target AP when signal strength is measured at multiple positions. The accuracy of the proposed scheme is evaluated through experiment.</P>