• Journal of the Korea Institute of Information Security & Cryptology
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• v.20 no.1
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• pp.123-128
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• 2010

Graph expression of attack scenarios is a necessary method for analysis of vulnerability in server as well as the design for defence against attack. Although various requirement analysis model are used for this expression, they are restrictive to express combination of complex scenarios. Role Based Petri Net suggested in this paper offer an efficient expression model based role on Petri Net which has the advantage of concurrency and visuality and can create unknown scenarios.

• Journal of the Korean Professional Engineers Association
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• v.44 no.5
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• pp.26-30
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• 2011

The hacking attacks as a DDoS attack on a telecommunications network has depleted the network resources. When hacking attack occurs a user can not access to the network and can not use the telecommunication services. Professional Engineers with expertise and experience in the field of Information and communication could play an important role to respond to the hacking attacks. Professional Engineers will build the information and communication network system for the hacking countermeasures.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05b
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• pp.209-212
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• 2006

Until now, sulfate attack is not completely understood. The purpose of this study is to provide a fundamental data to understand deterioration mechanism by sulfate attack. Chemical processes for products formed by sulfate attack were explained in this study. ASTM C1012 test and microstructural observations such as XRD and BSE analysis were carried out to manifest behavior and role of the products formed during sulfate attack. Regarding the dominant causes of sulfate attack, the main deterioration modes could be divided into 3 types; (1) expansive type, (2) onion-peeling type, and (3) acidic type.

• Journal of Korea Society of Digital Industry and Information Management
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• v.6 no.4
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• pp.153-160
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• 2010

MANET composed mobile nodes without central concentration control like base station communicate through multi-hop route among nodes. Accordingly, it is hard to maintain stability of network because topology of network change at any time owing to movement of mobile nodes. MANET has security problems because of node mobility and needs intrusion detection system that can detect attack of malicious nodes. Therefore, system is protected from malicious attack of intruder in this environment and it has to correspond to attack immediately. In this paper, we propose intrusion detection system based on rules in order to more accurate intrusion detection. Cluster head perform role of monitor node to raise monitor efficiency of packet. In order to evaluate performance of proposed method, we used jamming attack, selective forwarding attack, repetition attack.

• The Journal of the Korea Contents Association
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• v.5 no.6
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• pp.172-177
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• 2005

Hit judgement is essential factor in design for battle-style MMORPG game system and sets foundation for other game systems. Hit judgement model consists of attack power and attack rate. The former contains minimum, maximum, and critical attack, the latter has miss, hit, and critical blow rate. Random function generates one value of attack rate and consequently the damage is calculated. In this article, we propose hit judgement model which Is widely acceptable for generic MMORPG and describe the effort of applying the proposed model to Travia Online in detail.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.11
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• pp.5354-5369
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• 2019

Sensor networks are deployed in unheeded environment to monitor the situation. In view of the unheeded environment and by the nature of their communication channel sensor nodes are vulnerable to various attacks most commonly malicious packet dropping attacks namely blackhole, grayhole attack and sinkhole attack. In each of these attacks, the attackers capture the sensor nodes to inject fake details, to deceive other sensor nodes and to interrupt the network traffic by packet dropping. In all such attacks, the compromised node advertises itself with fake routing facts to draw its neighbor traffic and to plunge the data packets. False routing advertisement play vital role in deceiving genuine node in network. In this paper, behavior based routing misbehavior detection (BRMD) is designed in wireless sensor networks to detect false advertiser node in the network. Herein the sensor nodes are monitored by its neighbor. The node which attracts more neighbor traffic by fake routing advertisement and involves the malicious activities such as packet dropping, selective packet dropping and tampering data are detected by its various behaviors and isolated from the network. To estimate the effectiveness of the proposed technique, Network Simulator 2.34 is used. In addition packet delivery ratio, throughput and end-to-end delay of BRMD are compared with other existing routing protocols and as a consequence it is shown that BRMD performs better. The outcome also demonstrates that BRMD yields lesser false positive (less than 6%) and false negative (less than 4%) encountered in various attack detection.

• Wind and Structures
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• v.4 no.2
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• pp.131-146
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• 2001

A full-scale synchronized data acquisition system was set up on the roof of the experimental building at the Texas Tech University Wind Engineering Research Field Laboratory to simultaneously collect approaching wind data, conical vortex images, and roof corner suction pressure data. One-second conditional sampling technique has been applied in the data analysis, which makes it possible to separately evaluate the influencing effects of the horizontal wind angle of attack, ${\theta}$, and the vertical wind angle of attack, ${\varphi}$. Results show a clear cause-and-effect relationship between the incident wind, conical vortices, and the induced roof-corner high-suction pressures. The horizontal wind angle of attack, ${\theta}$, is shown to be the most significant factor in influencing the overall vortex structure and the suction pressures beneath. It is further revealed that the vertical wind angle of attack, ${\varphi}$, plays a critical role in generating the instantaneous peak suction pressures near the roof corner.

• Journal of the Korean Ceramic Society
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• v.44 no.9
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• pp.465-470
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• 2007

This paper presents an experimental study of the sulfate resistance of mortars and pastes exposed to sodium sulfate solutions up to one year. In order to check deterioration modes due to sulfate attack, the sodium sulfate solution was varied at three concentration steps (3,380, 10,140 and 33,800 ppm of $SO_4^{2-}$ ions), and maintained at ambient temperature. The tests include a visual examination, expansion and compressive strength loss measurements as well as x-ray diffraction tests. The experimental data indicated that the use of cement with a low $C_3A$ content and low silicate ratio has a beneficial effect on the sulfate attack of mortars. In contrast, the mortars with a high $C_3A$ content and high silicate ratio became severely degraded due to the formation of ettringite, gypsum and/or thaumasite in the cement matrix.

• Journal of Aerospace System Engineering
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• v.3 no.2
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• pp.1-11
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• 2009

A structural modelling for study on dynamic characteristics of tapered composite aircraft wings in the form of thin-walled beam is presented. The proposed structural model includes effects of transverse shear flexibility exhibited by the advanced composite materials and warping restraint characterizing elastic anisotropy and induced structural couplings. The complex effects of these factors could have a role in more efficient analysis on those structural models.

• Journal of the Society of Naval Architects of Korea
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• v.50 no.6
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• pp.421-428
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• 2013

This study aims at numerically investigating the angle of attack characteristics of the rudder behind a rotating propeller. The rotating propeller of 5 blades and the full spade rudder are placed in the numerical water tunnel with a uniform flow condition to consider propeller-rudder interaction. The turbulence closure model is employed to simulate the three-dimensional unsteady incompressible viscous turbulent flow around the propeller and the rudder. The present numerical method are well verified by comparing with the experimental results. In order to identify the dependence of the angle of attack of the rudder on the rudder angle, a wide range of rudder angles is considered. The present study carried out the quantitative and qualitative analysis of the angle of attack in terms of the pressure distribution, streamlines and the evaluation of the flow incidence, resulting in that the angle of attack increases as we move from the root and the tip to the center of the rudder, regardless of the rudder angle. The distribution of the angle-of-attack along the span is strongly affected by rotating propeller flow and rudder angle. Consequently, the distribution of the angle-of-attack of the oncoming flow against the rudder leading edge plays a role in determination of rudder performance.