• Convergence Security Journal
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• v.8 no.4
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• pp.173-181
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• 2008

Recently, Worm epidemic models have been developed in response to the cyber threats posed by worms in order to analyze their propagation and predict their spread. Some of the most important ones involve mathematical model techniques such as Epidemic(SI), KM (Kermack-MeKendrick), Two-Factor and AAWP(Analytical Active Worm Propagation). However, most models have several inherent limitations. For instance, they target worms that employ random scanning in the network such as CodeRed worm and it was able to be applied to the specified threats. Therefore, we propose the probabilistic of worm propagation based on the Markov Chain, which can be applied to cyber threats such as Mass SQL Injection worm. Using the proposed method in this paper, we can predict the occurrence probability and occurrence frequency for each threats in the entire system.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.184-184
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• 2010

Write-once-read-many times (WORM) 메모리 소자는 1회에 한해 쓰기 가능한 저장 장치로서 반영구적인 기록 보존을 필요로 하는 분야에서 널리 사용되는 저항 구조의 비휘발성 메모리 소자이다. 무기물을 사용한 WORM 메모리 소자의 제작과 소자의 전기적 특성에 관한 많은 연구가 활발히 진행되었으나 절연성 고분자인 Polystyrene (PS) 박막에 분산된 ZnO 나노입자를 이용한 무기물/유기물 복합 구조의 WORM 메모리 소자에 관한 연구는 상대적으로 미흡하다. 본 연구에서는 ZnO 나노입자가 분산되어 있는 PS를 스핀코팅 방법으로 박막 형태로 증착하여 WORM 메모리 소자를 제작하고 전기적인 성질을 조사하였다. 소자를 제작하기 위해 ZnO 나노 입자와 PS를 용매인 N,N-디메틸포메미드에 혼합하여 소자를 제작하였다. 그 후 하부 전극인 ITO가 증착되어 있는 유리 기판 위에 ZnO와 PS가 분산되어 있는 고분자 용액을 스핀 코팅 방법으로 도포한 후에 열을 가해 용매를 제거하여 박막을 형성하였다. ZnO 나노입자가 분산되어 있는 PS 박막 위에 Al을 상부 전극으로서 증착하였다. 전압을 인가하여 측정한 전류-전압 특성은 1.5 V에서 소자의 전도도가 크게 향상이 되는 것을 관측하였다. 읽기 전압에서 낮은 전도도(OFF 상태)와 높은 전도도 (ON 상태)의 크기는 $10^3$으로 이며, ON 상태가 된 이후에는 OFF 상태로 전환되지 않는 전형적인 WORM 메모리 소자의 특성이 관측되었다. ZnO 나노 입자가 없이 PS 만으로 박막을 제작한 소자는 쌍안정성 특성이 나타나지 않았다. 따라서 소자에서 전류 쌍안정성으로 나타난 원인은 PS안에 분산되어 있는 ZnO 나노입자에 기인함을 알 수 있었다. 제작된 WORM 메모리 소자의 기억 유지 특성에 대한 결과는 장시간에 걸친 측정에서 ON 전류 및 OFF 전류의 변화가 거의 없었다. 이 실험 결과는 제작된 무기물/유기물 복합 구조를 가진 WORM 메모리 소자는 우수한 기억 특성을 가지고 있으며 반영구적인 메모리 소자로 사용할 수 있음을 제시하고 있다.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.17 no.3
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• pp.43-53
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• 2007

Internet becomes more and more popular, and most companies and institutes use web services for e-business and many other purposes. With the explosion of Internet, the occurrence of cyber terrorism has grown very rapidly. Simulation is one of the most widely used method to study internet worms. But, it is quite challenging to simulate very large-scale worm attacks because of various reasons. In this paper, we propose a hybrid modeling method for RCS(Random Constant Spreading) worm simulation. The proposed hybrid model simulates worm attacks by synchronizing modeling network and packet network. So, this model will be both detailed enough to generate realistic packet traffic, and efficient enough to model a worm spreading through the Internet. Moreover, our model have the capability of dynamic updates of the modeling parameters. Finally, we simulate the hybrid model with the CodeRed worm to show validity of our proposed model for RCS worm simulation.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2013.05a
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• pp.521-522
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• 2013

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2009.06a
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• pp.731-732
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• 2009

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2008.06a
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• pp.727-728
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• 2008

• Journal of the Korean Society for Precision Engineering
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• v.28 no.1
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• pp.11-18
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• 2011

A worm screw is widely used in a geared motor unit for motion conversion from rotation to linear. For mass production of a high quality worm, the current rolling process is substituted with the milling process. Since the milling process enables the integration of all operations of worm manufacturing on a CNC(Computer Numerical Control) lathe, productivity can be remarkably improved. In this study, the tooling system for side milling on a CNC lathe to improve machinability is developed. However, the cutting tool-workpiece interference is important factors to be considered for producing high quality worms. For adaptability of various worms machining, the tool-workpiece interference simulation system based on a tool-tip trajectory model is developed. The developed simulation system is verified through several kinds of worms and experimental results.

• Transactions of the Korean Society of Automotive Engineers
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• v.22 no.1
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• pp.77-84
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• 2014

The worm gear is used in the motor drive system of automotive CVVL because of its compactness and self-locking ability. A ZK worm and an involute helical gear can be meshed in order to reduce production cost. However, the gearing is not suitable for the reliability and the NVH problem. To improve the dynamic performances, an optimal design process is considered. The transmission error is calculated theoretically and minimized with the several gear design parameters. An inequality condition such as the teeth interference elimination is added.

• Journal of Veterinary Clinics
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• v.16 no.2
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• pp.506-508
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• 1999

An one-year-old, female pointer dog with conjunctival hyperemia, corneal opaque and ocular pain in right eye was referred to Veterinary Medical Teaching Hospital, Chungbuk National University. In the ophthalmic examination the worm was observed in anterior chamber, The heart worm antigen test was positive. A modified Knott's test was negative. The values of complete blood count and serum chemistry (TP, BUN, creatinine, AST, ALT, ALP, albumin, globuline) showed normal ranges. Any abnormality was not detected in the heart using a thoracic radiography and cardiac sonography. Therefore, this dog was diagnosed as ocular filariasis. The worm was removed by surgical incision through a limbus of cornea. The closure of limbal incision was sutured in a simple interrupted suture pattern with 6-0 silk and the eye was reinflated with sterile saline solution. Antibiotics and dexamethasone ophthalmic solution were applied to right eye every 24 hours for 7 days. To prevent latent filariasis, ivermectin was also administered on day 14 of operation. The heart worm antigen test on day 60 was negative. The dog was successfully cured.

• Proceedings of the Korea Information Assurance Society Conference
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• 2004.05a
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• pp.333-337
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• 2004

The Internet worm is changed rapidly and virus vaccine can not defense the whole Internet worm. To prevent them form spreading into network and analysis specifications, we design and implement the Internet Worm Traffic Generator. In this research, we offer the real worm propagation environment through protocol and scenario specification.