• Journal of the Korean Geophysical Society
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• v.3 no.2
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• pp.127-138
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• 2000

This study was conducted to examine the differences between dynamic and static elastic constants by use of some laboratory tests of cement mortar specimens which have different water/cement mixing ratios. Specific gravity measurement, ultrasonic velocity estimating and uniaxial compression test were adopted to acquire the dynamic and static elastic constants. Digital data acquisition and processing enhanced the accuracy of estimating the velocities of specimens drastically, Also, the method using the gradient of propagation delay time in according to increment of specimen length more enhanced the accuracy than the method using the only one specimen length over total propagation time. The correlation between density and the P and S wave velocity of specimens shows reliable positive relation and the correlation between density and the strength of uniaxial compression has the similar relationship. The dynamic Young's modulus $(E_D)$ is alway greater than the static Young's modulus $(E_S)$ and there is increasing tendency of the ratio $(E_D/E_S)$ according to the increase of density or strength of the specimens. On the other hand, there is no typical relationship between dynamic Poisson's ratio $({\nu}_D)$ and static Poisson's ratio $({\nu}_S)$ and just the ratio of ${\nu}_D/{\nu}_S$ ranges front 69 to 122 %.

• The Journal of the Korea Contents Association
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• v.21 no.12
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• pp.896-905
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• 2021

In the field of SIEM(Security information and event management), many studies try to use a feedback system to solve lack of completeness of training data and false positives of new attack events that occur in the actual operation. However, the current feedback system requires too much human inputs to improve the running model and even so, those feedback from inexperienced analysts can affect the model performance negatively. Therefore, we propose "active model improving feedback technology" to solve the shortage of security analyst manpower, increasing false positive rates and degrading model performance. First, we cluster similar predicted events during the operation, calculate feedback priorities for those clusters and select and provide representative events from those highly prioritized clusters using XAI (eXplainable AI)-based event visualization. Once these events are feedbacked, we exclude less analogous events and then propagate the feedback throughout the clusters. Finally, these events are incrementally trained by an existing model. To verify the effectiveness of our proposal, we compared three distinct scenarios using PKDD2007 and CSIC2012. As a result, our proposal confirmed a 30% higher performance in all indicators compared to that of the model with no feedback and the current feedback system.

• Convergence Security Journal
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• v.18 no.5_2
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• pp.3-10
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• 2018

The drone is an unmanned aircraft that can be steered and controlled using radio waves on the ground, and the pilot moves unmanned without boarding. The history of the unmanned airplane began with military use, and the first unmanned aerial flight was the first successful flight of the 'Sperry Aerial Torpedo' drones built in the United States in 1917 with a bomb. With the development of unmanned aerial technology, the use of military drones has expanded to a wider field. Recently, the use of drones has been utilized in various fields such as agriculture, industry, logistics, broadcasting, and safety, and the scale of the market is also expanding. Although the drones are becoming indispensable to penetrate our lives, they can be used for bad purposes depending on the intended use of the user, but the risk factors are overlooked. Therefore, technical defects related to drones and accidents caused by operator's mistakes can not be completely prevented. However, privacy infringement, security leakage, and terrorism, which may be caused by illegal use of drones, It will not be inhibited and will accelerate.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.24 no.8
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• pp.1052-1057
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• 2020

With the development of new ICT technology, smart keys for vehicles are terminals with ICT technology. Therefore, when the vehicle and the smart key communicate with RF, a cyber hacking attack is possible. Cyber-attacks on smart keys can pose a threat to vehicle theft and vehicle control. Therefore, it is necessary to study hacking attacks and vulnerabilities of smart keys for autonomous vehicles. In this paper, we analyze the cyber attack case of RF communication for vehicles and smart keys. In addition, a real RF cyber attack on the smart key is performed, and the vulnerability of radio wave replication in the same frequency band is found. In this paper, we analyze the vulnerability of RF communication between vehicles and smart keys, and propose a countermeasure against cyber security. In the future, plans to strengthen cyber attacks and security through the popularization of autonomous vehicles will become basic data to protect human and vehicle safety.

• Journal of Digital Convergence
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• v.19 no.7
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• pp.209-215
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• 2021

This study is a system development for voice information protection equipment in major meetings and places requiring security. Security performance and stability were secured with information leakage prevention technology through generation of false noise and ultrasonic waves. The cutoff frequency band for blocking the leakage of voice information, which has strong straightness due to the nature of the radio wave to the recording prevention module, blocks the wideband frequency of 20~20,000Hz, and the deception jamming technology is applied to block the leakage of voice information, greatly improving the security. To solve this problem, we developed a system that blocks the recording of a portable smartphone using a battery, and made the installation of a separate device smaller and lighter so that customers do not recognize it. In addition, it is necessary to continuously study measures and countermeasures for efficiently using the output of the anti-recording speaker for long-distance recording prevention.

• Korean Security Journal
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• no.28
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• pp.103-130
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• 2011

This study is the research of enterprise security for raising the profitability and stability of Korean companies in global business environment and strategic cooperation of business. As the scientific technology gets complicated as day goes by and new competitors appear regardless the border in the modern business environment, the situation happens frequently which the huge company hands over their market to the new one armed with the innovative thinking overnight. To survive such new environment, the answer is the change of paradigm regarding business management method at the new point of view. With the low level of security risk management of Korean companies which stick to old habit, the security management which helps the companies secure profits is not affordable. The global village where the population of 7 billions live in 21st century is facing up to the rapid ecological adaptation. The rapid change of climatic environment creates the hundreds of thousands of sufferers in a moment, and we have been watching the millions of livestock are buried alive due to new contagious disease everyday. Such change encourages the humans in global village to change the basic way of living. The business ecosystem which is the basic root for economic life cannot be an exception. To survive the business environment of 21st century, the security risk management at management level is required and the reporting line of companies should be established newly for raising business competing power through security risk management. The companies should bear in mind that they can be disappeared into our old memories overnight if they are not sensitive to the changing environment. Out of new risks for the modern companies, the field especially Korean companies are dealing easily is the security risk. Not like past, the security risk which's size is much more massive and its propagation velocity is very fast is the one of important business risks which the management should take care. Out of security risks which influence on the modern companies significantly, the brand of companies, protection of their reputation, continuity of production and operation and keeping customer's trust are prior to the others. This study offered the suggestion regarding enterprise security and the strategic cooperation of business to deal with such security risk effectively.

• Proceedings of the Korean Information Science Society Conference
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• 2005.11a
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• pp.67-69
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• 2005

현재까지의 보안 라우팅 프로토콜은 유무선에 관계 없이 페이로드 부분은 암호화가 되더라도 패킷 헤더의 내용이 평문 형태로 무방비하게 노출되며 라우팅 경로가 안전하게 보장되더라도 악의적인 노드에게 경로가 알려지는 것을 차단 할 수 없다. 또한 유선 환경과는 달리 Ad-hoc 네트워크와 같은 무선 상황에서는 전파의 전방향성 때문에 송수신 범위 내에 있는 노드들이 평문 형태의 라우팅 정보 및 송수신 노드의 정보를 수집하는 것을 방지 할 수 없다. 본 논문에서 제안하는 은닉 라우팅 프로토콜은 한쌍의 노드가 비대칭키 암호화 알고리즘을 통해 공유한 초증가 수열을 통해 송수신 노드를 은닉하면서도 정당한 수신 노드만 자신이 수신 노드임을 알 수 있는 기법을 제공함으로서 악의적인 노드가 라우팅 경로에 대한 정보를 수집하는 것을 원천적으로 차단한다.

• Electronics and Telecommunications Trends
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• v.27 no.5
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• pp.73-84
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• 2012

테라헤르츠파는 0.1~10THz 대역의 미개발 주파수 자원으로 전자기파 스펙트럼에서 적외선과 밀리미터파의 중간 영역에 위치한다. 전파의 투과성과 광파의 직진성을 동시에 가지고 있어 독특한 물리적 특성을 보유한 테라헤르츠파는 THz 소자, 분광, 영상 기술 등의 기초 과학과 의공학, 보안, 환경/우주, 정보통신 등의 응용 과학 분야에서 이미 그 중요성이 검증되어 향후 폭넓은 산업 응용으로 다양한 분야에서 새로운 형태의 시장이 형성될 것으로 기대된다. 이러한 테라헤르츠파 기술의 사회, 경제적 파급력을 극대화하기 위해서는 테라헤르츠 대역 소자의 특성을 향상시키고, 크기와 가격을 낮추는 것이 매우 중요하다. 본고에서는 크기와 가격을 낮출 수 있는 포토닉스 기반의 테라헤르츠 가변형 연속파 신호원 및 검출기 기술과 이를 기반으로 구현 가능한 응용 기술 동향에 대하여 기술하였다.

• Proceedings of the Korean Information Science Society Conference
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• 2004.04a
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• pp.295-297
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• 2004

현대 사회는 무선통신 기술의 급속한 발달로 인해 사용자가 자신의 위치에 상관없이 어디서든지 네트워크에 접속하여 서비스를 제공받을 수 있게 되었다. 하지만, 무선은 유선에 비해 상대적으로 보안에 취약하여 정보보호에 특별한 주의가 필요하다. 유선 네트워크는 침투를 위해서 물리적으로 침투위치를 확보해야만 공격을 수행할 수 있었으나, 무선의 경우에는 전파도달 거리내의 아무 곳에서나 공격을 시도할 수 있어 무선랜을 통한 많은 공격시도가 현실화되고 있다. 또한 공격자가 공공장소, 대학교, 카페 등의 개방된 곳에서 자신이 습득한 다른 사용자의 ID를 사용하여 공중 무선랜 서비스에 접속하여 어느 특정 기관을 공격, 해킹 할 경우에 공격 근원지와 공격자에 대한 추적이 사실상 불가능하다. 이러한 무선랜이 갖는 취약성을 보완하고 안전한 무선랜 환경을 구축하기 위해서, 본 논문에서는 무선랜 장비인 AP를 이용하여 침입자를 탐지하는 방법을 제시하고 있다. 제시된 방법은 현재 사용되어지고 있는 무선랜 환경에 추가적인 장비의 도입을 하지 않고, AP의 기능을 이용하는 방법을 제시하고 있다. 향후 AP와 무선 센서를 기반으로 하여 좀 더 정밀하고, 정확하게 침입자를 탐지하는 기술을 보강할 예정이다.

• 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.