• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2014년도 춘계학술대회
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• pp.230-233
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• 2014

최근 보안 위협과 위험이 매우 빠른 속도로 변화하고 있어, 다각화 되는 공격기법에 대응하기 위한 필수 조건으로 기업 및 기관에서 모의 침투 테스트를 진행하고 있다. 침투 테스트(Penetration Test, PenTest)는 합법적이고 승인된 시도로 컴퓨터 시스템을 더 안전하게 하기 위해 시스템의 취약점을 찾아내고, 찾아낸 취약점에 대해 공격을 시도하는 것이다. 모의 해킹 테스트와 같은 용어로 사용되고 있으며 취약점이 어떻게 악용될 수 있는지 공격을 시도하여 보여준다. 한편, 현재 많은 보안업체에서 다양한 방법 및 절차로 침투 테스트를 수행하고 있으나, 실제로 이러한 테스트의 강도와 신뢰성에 대한 평가는 아직 이루어지지 않고 있다. 따라서, 본 연구에서는 이와 같은 침투 테스트에 대하여 검증되고 신뢰할 수 있는 평가 방법을 제시한다. 본 연구에서 제시한 침투 테스트 평가 정보를 활용하여 보다 신뢰할 수 있는 평가 결과를 얻을 수 있고, 결과적으로 효율적인 침투 테스트가 가능할 것으로 기대된다.

• 한국정보통신학회논문지
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• 제24권12호
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• pp.1670-1675
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• 2020

본 연구에서는 DRDoS 공격에 대한 효과적인 네트워크 기반 대응책을 수립하는데 필요한 기초 자료를 제공하고자, DRDoS의 네트워크 기반 특징을 식별하고 이에 대한 확률 및 통계 기법을 적용한 새로운 'DRDoS 공격 다단계 탐지기법'을 제안하고자 한다. 제안된 기법은 DRDoS의 특징인 반사 서버의 증폭에 의한 네트워크 대역폭에서 무제한 경쟁으로 정상적인 트래픽이 무분별하게 차단될 수 있는 한계를 제거하고자 'Server to Server' 및 이에 대한 'Outbound 세션 증적' 여부를 비교하여 정확한 DRDoS 식별 및 탐지가 가능하고 이에 대한 트래픽에 대해서만 통계 및 확률적 임계값을 적용하기에, 네트워크 기반 정보보호 제품은 이를 활용하여 완벽하게 DRDoS 공격 프레임을 제거가 가능하다. 시험을 통해 제안한 기법이 DRDoS 공격에 대한 식별 및 탐지 정확성을 높이고 희생자 서버의 서비스 가용성을 확보함을 확인하였다. 따라서 본 연구결과는 DRDoS 공격 식별 및 대응에 크게 기여할 수 있을 것으로 기대한다.

• 한국산학기술학회논문지
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• 제21권8호
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• pp.147-153
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• 2020

헬기와 같은 항공기의 신규 개발에는 시제품 설계 및 제작과 함께 많은 시간동안 비행시험을 통한 안전성 검증이 요구된다. 비행시험을 수행하는 시험평가 단계는 시스템의 개발에 있어 성공을 좌우하는 중요한 과정이며, 특히, 공격헬기 개발을 위해서는 무장분야 비행시험을 통한 안전성 검증이 매우 중요하다. 이러한 공격헬기의 개발에 있어서 무장분야 비행시험 관련 시험평가 기간 및 비용은 비행시험의 소요탄약 발수와 밀접한 관계가 있다. 따라서, 본 논문에서는 미 군사 규격인 ADS-44-HDBK와 유사 사례로 AH-1 헬기의 분석을 통해 공격헬기 개발 간 무장분야 비행시험에 요구되는 탄약소요량을 제시하였다. AH-1 헬기의 사례 분석을 통해 중복 사격시험 배제 및 형상차이를 고려하여 탄약 요구량 산출이 가능하며, 기관총 장착 형상의 경우 사격시험 관련 탄약이 약 10,500R 요구되고, 로켓 장착 형상의 경우 사격시험 관련 탄약이 약 324R 요구된다. 또한, 무장통합벤치를 적절하게 사용을 한다면 무장분야 비행시험간 발생 가능한 위험요소 식별하여 미연에 배제함으로써 무장분야 비행시험의 효율적 추진이 예상된다.

• Journal of information and communication convergence engineering
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• 제12권1호
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• pp.33-38
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• 2014

This paper investigates the shaping operation problem introduced by Callahan et al., namely the k-fragility maximization problem (k-FMP), whose goal is to find a subset of personals within a terrorist group such that the regeneration capability of the residual group without the personals is minimized. To improve the impact of the shaping operation, the degree centrality of the residual graph needs to be maximized. In this paper, we propose a new greedy algorithm for k-FMP. We discover some interesting discrete properties and use this to design a more thorough greedy algorithm for k-FMP. Our simulation result shows that the proposed algorithm outperforms Callahan et al.'s algorithm in terms of maximizing degree centrality. While our algorithm incurs higher running time (factor of k), given that the applications of the problem is expected to allow sufficient amount of time for thorough computation and k is expected to be much smaller than the size of input graph in reality, our algorithm has a better merit in practice.

• 방사성폐기물학회지
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• 제19권1호
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• pp.39-49
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• 2021

The behaviors of various desorption agents were investigated during the desorption of cesium (Cs) from samples of clay minerals and actual soil. Results showed that polymeric cation exchange agents (polyethyleneimine (PEI)) efficiently desorbed Cs from expandable montmorillonite, whereas acidic desorption solutions containing HCl or PEI removed considerable Cs from hydrobiotite. However, most desorption agents could desorb only 54% of Cs from illite because of Cs's specific adsorption to selective adsorption sites. Cs desorption from an actual soil sample containing Cs-selective clay mineral illite (< 200 ㎛) and extracted from near South Korea's Kori Nuclear Power Plant was also investigated. Considerable adsorbed 137Cs was expected to be located at Cs-selective sites when the 137Cs loading was much lower than the sample's cation exchange capacity. At this low 137Cs loading, the total Cs amount desorbed by repeated washing varied by desorption agent in the order HCl > PEI > NH4+, and the highest Cs desorption amount achieved using HCl was 83%. Unlike other desorption agents with only cation exchange capabilities, HCl can attack minerals and induce dissolution of metallic elements. HCl's ability to both alter minerals and induce H+/Cs+ ion exchange is expected to promote Cs desorption from actual soil samples.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 정기총회 및 추계학술대회 논문집
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• pp.287-296
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• 2011

Turnout is a mechanical installation enabling railway trains to be guided from one track to another at a railway junction. A movable nose crossing frog is a device used at a railway turnout to eliminate the gap at the common crossing (High manganese, block, assembly crossing)which can cause impact damage, noise and vibration. Our government has a plan speed up of conventional line to 250km/h semi-high speed. We had already developed flexible turnout with fixed crossing(High manganese) and SFC fastening system can cover in the semi-high speed line In this study is about development of the movable nose crossing turnout available Semi-high speed line on concrete track. This paper describes about geometry, attack angle, bending stress at the nose, switching force, safety of continuous welded long rails. This movable nose crossing turnout is expected greatly increases passing speed of turnout in national railway.

• International Journal of Aeronautical and Space Sciences
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• 제14권1호
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• pp.1-10
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• 2013

This is a written version of the keynote speech delivered at the International Symposium on Hypersonic Aerothermodynamics - Recent Advances held in Bangalore, India, from December $6^{th}$ to $10^{th}$, 2012. In this document, what was accomplished in the past, the present status, and what is expected in the future in the field of hypersonic aerothermodynamics are reviewed. Solved problems are categorized into four items; unsolved problems into twelve items, and emerging problems into four items. Removing one degree uncertainty in trim angle of attack, studying the thermochemical phenomena in a hydrogen-helium-methane mixture, and entry flights of meteoroids are cited as the tasks for the future.

• Journal of Advanced Marine Engineering and Technology
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• 제30권1호
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• pp.150-156
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• 2006

A Flapping foil Produces an effective angle of attack, resulting in a normal force vector with thrust and lift components, and it can be expected to be a new highly effective propulsion system. A heaving foil model was made and it was operated within a circulating water channel at low Reynolds numbers. The unsteady thrust and lift acting on the heaving foil were measured simultaneously using a 6-axis force sensor based on force and moment detectors. We have been examined various conditions such as heaving frequency and amplitude in NACA 0010 Profile. The results showed that thrust coefficient and efficiency increased with reduced frequency and amplitude. We also Presented the experimental results on the unsteady fluid forces of a heaving foil at various Parameters.

• 대한기계학회논문집A
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• 제29권5호
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• pp.639-646
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• 2005

As the internet communication is prevalent in recent years, it becomes quite possible to monitor and control some mechanical plants from the remote place through the TCP/IP communication. Such a concept is expected to be applied to many industrial systems fur easy maintenance and trouble shooting as well as various kinds of expensive test equipments fo. sharing. Synthetic jet actuate.(SJA) is a kind of high-lifting device to prevent flow separation at high angle of attack and its use for flow control has received a great amount of attention. In this research, remote control and data monitoring system for SJA wind tunnel test is implemented by TCP/IP communication with DSP as a embedded web server. From the tests performed with embedded server, it showed the possibility of reliable remote control system design utilizing the internet communication.

• 한국군사과학기술학회지
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• 제11권6호
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• pp.5-13
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• 2008

A smart submunition drops through the expected trajectory to have a appropriate target searching footprint for the armored ground vehicles. Parachutes can be used as a tool to decelerate and spin the submunition. Usually submunition's descent velocity, spin rate, submunition inclination angle against vertical and dynamic stability affect to its target searching footprint. Therefore it is important to design optimal parachute and load configuration for the overall system performance. In this paper we described the dynamic motion of submunition by the mathematical model of parachute and load. Through the computer simulation we can analyze the submunition footprint affected by parachute and load design.