• KSII Transactions on Internet and Information Systems (TIIS)
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• v.4 no.2
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• pp.191-204
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• 2010

There is a well-defined propagation model, named the random constant spread (RCS) model, which explains worms that spread their clones with a random scanning strategy. This model uses the number of infected hosts in a domain as a factor in the worms' propagation. However, there are difficulties in explaining the characteristics of new Internet worms because they have several considerable new features: the denial of service by network saturation, the utilization of a faster scanning strategy, a smaller size in the worm's propagation packet, and to cause maximum damage before human-mediated responses are possible. Therefore, more effective factors are required instead of the number of infected hosts. In this paper, the network bandwidth usage rate is found to be an effective factor that explains the propagations of the new Internet worms with the random scanning strategy. The analysis and simulation results are presented using this factor. The simulation results show that the scan rate is more sensitive than the propagation packet for detecting worms' propagations.

• Proceedings of the KSME Conference
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• 2001.06c
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• pp.470-475
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• 2001

The elevator gear box with the helical gears needs to be developed instead of the one with the worm gears to improve the efficiency. In order to develop the gear box, the analytical tool to predict the helical gear noise is necessary to meet customer's noise requirement. Gear noise is related to the loaded transmission error. Therefore, the simulation program for the loaded transmission error analysis of the helical gears is developed in this study. Using the developed program, the effects of tooth modification such as tip relief and the extent of tip relief are investigated. Finally, the procedures to determine the tip relief and the extent of tip relief are proposed.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.12
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• pp.2695-2702
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• 2002

The elevator gear box with the helical gears needs to be developed instead of the one with the worm gears to improve the efficiency. In order to develop the gear box, the analytical tool to predict the helical gear noise is necessary to meet customer's noise requirement. Gear noise is related to the loaded transmission error. Therefore, the simulation program fer the loaded transmission error analysis of the helical gears is developed in this study. Using the developed program, the effects of tooth modification such as tip relief and the extent of tip relief are investigated. Finally, the procedures to determine the tip relief and the extent of tip relief are proposed.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2018.05a
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• pp.234-235
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• 2018

The development of insulation,the most important factor, is slow. The curtain wall market is getting bigger as the bulidings are getting bigger, but the insulation of the window is getting a problem. In order to solve this problem, we want to develop the insulation block used in the window frames. We will examine the insulation effect by using the existing Azon insulation block and the thermal worm convex which is to be developed with Therm 7.4 program.

• Journal of Power System Engineering
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• v.12 no.1
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• pp.80-86
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• 2008

A motor cylinder apparatus is used to transfer a load in industrial applications. The apparatus is composed of a motor and power transmission elements such as worm gear and screw. In this case, the nonlinear friction of the transmission elements has a bad influence on the position control performance. To overcome this problem, the position control system consists of a feedback controller to achieve nominal control performance and a disturbance observer to compensate nonlinear friction. Especially the filter of a disturbance observer is designed from viewpoint of robust stability. Finally, the simulation result shows that the proposed control system is effective for the disturbance elimination as well as the friction compensation.

• Proceedings of the Korean Information Science Society Conference
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• 2005.07a
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• pp.214-216
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• 2005

현재 인터넷 웜에 관한 관심과 연구가 활발해 지면서 인터넷 웜 전파 특성 시뮬레이션 방법에 관한 연구가 많이 진행 되고 있다. 하지만, 연구 되어온 기법들은 대부분 웜의 스캔기법과 같은 웜 자체에 전파 되는 알고리즘에 대해서만 고려한 시뮬레이션 환경을 제시 하였다. 웜의 특성 상 좀더 실제 네트워크 환경과 비슷한 환경을 제공 하려면, 웜의 전파 알고리즘 외에, 각 호스트들에 취약점 패치 유무, 타깃 호스트들의 Computing Power, 각 네트워크의 밴드위스 & 지연시간, 네트워크 별 보안 장비(방화벽, IPS)의 유무 등 여러 가지 웜 전파에 영향을 미치는 요소들이 존재한다. 따라서 본 연구에서는 먼저 웜의 전파에 영향을 미치는 요소를 특성에 따라 크게 4가지로 분류 해보고, 이를 효율적으로 시뮬레이션 환경에 적용 할 수 있는 방안을 제안한다.

• The Journal of the Korea Contents Association
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• v.5 no.2
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• pp.115-121
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• 2005

In the present internet environment, various traffic flooding attacks and worm attacks cause economical loss. If IPv4 is substituted by IPv6 because of the lack of IP address, it will be more serious. Therefore, we design and implement the traffic analysis tool which can detect attacks by expecting them encountered in the IPv6 environment. Proposed tool is composed of packet generation module, packet gathering module, discrimination module, and display module in X-windows. As a simulation result, it is proved that it can effectively detect DAD-NA message attack, TCP SYN flooding attack, UDP flooding attack and ICMP flooding attack in the IPv6 environment.

• Journal of the Korean Society for Precision Engineering
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• v.28 no.3
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• pp.285-291
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• 2011

The error motion of a machine tool spindle directly affects the surface errors of machined parts. The error motions of the spindle are not desired errors in the three linear direction motions and two rotating motions. Those are usually due to the imperfect of bearings, stiffness of spindle, assembly errors, external force or unbalance of rotors. The error motions of the spindle have been needed to be decreased to desired goal of spindle's performance. The level of error motion is needed to be estimated during the design and assembly process of the spindle. In this paper, the estimation method for the five degree of freedom (5 D.O.F) error motions of the spindle is suggested. To estimate the error motions of the spindle, waviness of shaft and bearings, external force model was used as input data. And, the estimation models are considering geometric relationship and force equilibrium of the five degree of the freedom. To calculate error motions of the spindle, not only imperfection of the shaft, bearings, such as rolling element bearing, hydrostatic bearing, and aerostatic bearing, but also driving elements such as worm, pulley, and direct driving motor systems, were considered.

• Transactions of the Society of Information Storage Systems
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• v.3 no.1
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• pp.34-39
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• 2007

Super-REsolution Near-field Structure (Super-RENS) 재생 현상을 모델링하고 재생 신호를 계산하여 실험 결과와 비교하였다. 약 2mW 내외의 높은 광 파워로 집광된 Spot 은 디스크 내의 상변화 물질인 GST 를 용융시키므로 집광 Spot 내에는 용융 영역과 비 용융 영역이 공존하게 되고 연속적 또는 불연속적인 경계를 이루게 된다. 이러한 열 효과로부터 기인하는 집광 Spot 내에서의 물질의 광학적 특성 변화와 변화 정도의 차이를 가정하였고 변화된 광학적 특성은 집광된 Spot 의 유효 크기를 줄어들게 함으로써 회절한계 이하의 정보를 재생 가능하게 한다. 계산은 FDTD 방법과 Scalar 방법을 병행하였다. FDTD 방법으로는 위와 같은 집광 Spot 내의 물질 굴절률 (n,k) 변화로부터 회절한계 이하의 정보가 재생 가능함과 CNR 문턱 현상을 확인하였고, Scalar 방법으로는 물질 굴절률을 직접 다루지 않고 굴절률 변화로부터 기인하는 광의 Amplitude 와 Phase 변화로부터 회절한계 이하의 정보가 재생 가능함을 확인하였다. 이 때 광의 Amplitude 와 Phase 변화를 모델링하기 위하여 지름, 위치, 반사율 변화량, 위상 변화량의 네가지 변수로 정의되는 광 마스크를 도입하였다. Scalar 방법을 이용하여 재생 RF 신호 등 다양한 Super-RENS 디스크의 신호를 계산 활용 할 수 있고 다음의 두가지 광학계에 대하여 계산과 실험으로 얻은 채널 특성 및 RF 신호를 비교하여 각각 오차평균 4.2%, 4.7%로 일치함을 확인하였다. 파장 659nm, NA=0.6, Min Pit Length=173nm ROM 디스크 System, 파장 405nm, NA=0.85 Min Mark Length=75nm WORM 디스크 System.

• Journal of Internet Computing and Services
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• v.13 no.2
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• pp.41-49
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• 2012

Wireless network support and extended mobile network environment with exponential growth of smart phone users allow us to utilize the network anytime or anywhere. Malicious attacks such as distributed DOS, internet worm, e-mail virus and so on through high-speed networks increase and the number of patterns is dramatically increasing accordingly by increasing network traffic due to this internet technology development. To detect the patterns in intrusion detection systems, an existing research proposed an efficient algorithm called the jumping window algorithm and analyzed approximately 2,000 patterns in Snort 2.1.0, the most famous intrusion detection system. using the algorithm. However, it is inappropriate from the number of TCAM lookups and TCAM memory efficiency to use the result proposed in the research in current environment (Snort 2.9.0) that has longer patterns and a lot of patterns because the jumping window algorithm is affected by the number of patterns and pattern length. In this paper, we simulate the number of TCAM lookups and the required TCAM size in the jumping window with approximately 8,100 patterns from Snort-2.9.0 rules, and then analyse the simulation result. While Snort 2.1.0 requires 16-byte window and 9Mb TCAM size to show the most effective performance as proposed in the previous research, in this paper we suggest 16-byte window and 4 18Mb-TCAMs which are cascaded in Snort 2.9.0 environment.