• 정보보호학회논문지
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• 제11권6호
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• pp.115-125
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• 2001

분산환경의 정보보호를 위해 인증 및 접근통제 서비스는 필수적인 요구 사항이다. 권한위임은 개시자 편에서 중개자가 목적지 응용서비스의 접근권한을 허용하는 과정으로 분산환경에서 안전성을 유지하면서 서비스의 가용성을 증대시키는 방법이다. 단일 도메인 내에서 역할기반 접근통제(RBAC) 권한위임이 용이하게 제공된다. 그러나 다중 도메인 환경에서 도메인간 개시자가 중개자에게 문서공유를 위해 권한위임을 요청할 경우 권한남용 방지를 위해서 접근권리을 제한하여 처리할 수 있도록 권한위임 제약 기능이 필요하다. 본 논문에서 문서공유 문제를 RBAC으로 해결하고자 권한위임 제약을 하는 권한위임 뷰를 제안한다. 제안된 모델은 다중 권한위임에서 발생하는 문서과잉 노출을 방지할 뿐만 아니라 통신 및 시스템의 과부하 현상방지, 효율적인 보안관리가 가능하다.

• International Journal of Naval Architecture and Ocean Engineering
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• 제12권1호
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• pp.241-257
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• 2020

The rapid proliferation of oil/gas drilling and wind turbine installations with jack-up rig-formed structures increases structural safety requirements, due to the greater risks of operational collisions during use of these structures. Therefore, current industrial practices and regulations have tended to increase the required accidental collision design loads (impact energies) for jack-up rigs. However, the existing simplified design approach tends to be limited to the design and prediction of local members due to the difficulty in applying the increased uniform impact energy to a brace member without regard for the member's position. It is therefore necessary to define accidental load estimation in terms of a reasonable collision scenario and its application to the structural response analysis. We found by a collision probabilistic approach that the kinetic energy ranged from a minimum of 9 MJ to a maximum 1049 MJ. Only 6% of these values are less than the 35 MJ recommendation of DNV-GL (2013). This study assumed and applied a representative design load of 196.2 MN for an impact load of 20,000 tons. Based on this design load, the detailed design of a leg structure was numerically verified via an FE analysis comprising three categories: linear analysis, buckling analysis and progressive collapse analysis. Based on the numerical results from this analysis, it was possible to predict the collapse mode and position of each member in relation to the collision load. This study provided a collision strength assessment between attendant vessels and a jack-up rig based on probabilistic collision scenarios and nonlinear structural analysis. The numerical results of this study also afforded reasonable evaluation criteria and specific evaluation procedures.

• Earthquakes and Structures
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• 제20권3호
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• pp.325-335
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• 2021

The majority of Turkey's geography is at risk of earthquakes. Within the borders of Turkey, including the two major active faults contain the North-Eastern and Eastern Anatolia, earthquake, threatening the safety of life and property. On January 24, 2020, an earthquake of magnitude 6.8 occurred at 8:55 p.m. local time. According to the data obtained from the stations in the region, peak ground acceleration in the east-west direction was measured as 0.292 g from the 2308 coded station in Sivrice. It is thought that the earthquake with a magnitude of Mw 6.8 was developed on the Sivrice-Puturge segment of the Eastern Anatolian Fault, which is a left lateral strike slip fault, and the tear developed in an area of 50-55 km. Aftershocks ranging from 0.8 to 5.1 Mw occurred following the main shock on the Eastern Anatolian Fault. The earthquake caused severe structural damages in Elazığ and neighboring provinces. As a result of the field investigations carried out in this study, significant damage levels were observed in the buildings since it did not meet the criteria in the earthquake codes. Within the study's scope, the structural damage cases in reinforced concrete and masonry structures were investigated. Many structural deficiencies and mistakes such as non-ductile details, poor concrete quality, short columns, strong beams-weak columns mechanism, large and heavy overhangs, masonry building damages and inadequate reinforcement arrangements were observed. Requirements of seismic codes are discussed and compared with observed earthquake damage.

• Nuclear Engineering and Technology
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• 제54권1호
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• pp.84-96
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• 2022

In the worst case, a temporary ignition source (also known as transient combustibles) between two electrical panels can damage both panels. Mitigation strategies for electrical panel fires were previously developed using fire modeling and risk analysis. However, since they do not comply with deterministic fire protection requirements, it is necessary to analyze the boundary values at which combustibles may damage targets depending on various factors. In the present study, a sensitivity analysis of input variables related to the damage threshold of two electrical panels was performed for dimensionless geometry using a Fire Dynamics Simulator (FDS). A new methodology using a damage evaluation map was developed to assess the damage of the electrical panel. The input variables were the distance between the electrical panels, the vertical height of the fuel, the size of the fire, the wind speed and the wind direction. The heat flux was determined to increase as the vertical distance between the fuel and the panel decreased, and the largest heat flux was predicted when the vertical separation distance divided by one half flame length was 0.3-0.5. As the distance between the panels increases, the heat flux decreases according to the power law, and damage can be avoided when the distance between the fuel and the panel is twice the length of the panel. When the wind direction is east and south, to avoid damage to the electrical panel the distance must be increased by 1.5 times compared to no wind. The present scale model can be applied to any configuration where combustibles are located between two electrical panels, and can provide useful guidance for the design of redundant electrical panels.

• 한국항공우주학회지
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• 제50권10호
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• pp.739-745
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• 2022

전투기의 여러 가지 환경 요구도 중 폭발성 대기는 항공기 체계와 승무원의 안전을 위해 군수품의 점화 여부를 확인하는 시험이다. 시험은 한국생산기술연구원(KITECH)에서 보유하고 있는 폭발성 대기 시험장비를 활용하였고, 보수적으로 시험을 수행하기 위해 일반 연료보다 점화 특성이 민감한 n-hexane을 사용하였다. 미 군용 환경시험 규격서인 MIL-STD-810G w/Change 1, Method 511.6, Procedure I을 바탕으로 적용 범위와 테일러링(Tailoring) 가이드, 세부 시험절차를 확인하고 전투기의 각 계통에 대한 본 시험의 필요성을 고찰한다. 본 연구를 통해 전투기에 장착되는 구성품에 대한 폭발성 대기 시험 결과를 분석하고, 도출한 주안점을 공유하여 올바른 테일러링 방안을 제시한다.

• 정보보호학회논문지
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• 제32권5호
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• pp.891-898
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• 2022

세계적 관심과 함께 드론은 물품 수송, 산림 보호, 안전 관리 등 활용 분야의 저변을 확대해 나가고 있으며 드론은 활용 분야 확대 및 규모 확장에 따라 군사 작전, 환경 감시 등 다양한 분야에서 군집 비행이 응용되고 있다. 현재 국내에서는 특정 산업 분야의 서비스를 위한 이음 5G와 같은 특화망을 구축해 나가고 있다. 이와 관련하여 드론 시스템 또한 AI와 자율비행 등과 융합된 서비스를 제공하기 위해 특화망을 구축하려는 움직임이 보이고 있다. 드론이 여러 서비스와 융합됨에 따라 다양한 환경에서의 다양한 보안 위협 또한 종속되고 있으며, 이에 대응하여 국내에서는 드론 보안에 대한 요구사항과 가이드라인을 마련하고 있는 추세이다. 본 논문에서는 드론 시스템 중 드론의 군집 비행 시스템과 이를 위한 이음 5G와 같은 이동통신 특화망에서 무선랜과 양자 엔트로피 기반 난수 발생기를 탑재한 암호모듈을 활용하여 군집 비행 드론 간 피아식별 및 안전한 정보 제공 기술 방법을 제안하고, 구현에 참고할 수 있는 테스트 벡터를 제공한다.

• Geomechanics and Engineering
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• 제27권6호
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• pp.561-571
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• 2021

Cofferdams made of teel sheet piles are commonly utilized as support structures for excavation of sea-crossing bridge foundations. As cofferdams are often subject to tide variation, it is imperative to consider potential effects of tide on stability and serviceability of sheet piles, particularly, ultralong steel sheet piles (USSPs). In this study, a real USSP cofferdam constructed using new construction technology in Nanxi River was reported. The design of key parts of USSP cofferdam in the presence of tidal action was first introduced followed by the description of entire construction technology and associated monitoring results. Subsequently, a three-dimensional finite-element model corresponding to all construction steps was established to back-analyze measured deflection of USSPs. Finally, a series of parametric studies was carried out to investigate effects of tide level, soil parameters, support stiffness and construction sequence on lateral deflection of USSPs. Monitoring results indicate that the maximum deflection during construction occurred near the riverbed. In addition, measured stress of USSPs showed that stability of USSP cofferdam strengthened as construction stages proceeded. Moreover, the numerical back-analysis demonstrated that the USSP cofferdam fulfilled the safety requirements for construction under tidal action. The maximum deflection of USSPs subject to high tide was only 13.57 mm at a depth of -4 m. Sensitivity analyses results showed that the design of USSP cofferdam system must be further improved for construction in cohesionless soils. Furthermore, the 5th strut level before concreting played an indispensable role in controlling lateral deflection of USSPs. It was also observed that pumping out water before concreting base slab could greatly simplify and benefit construction program. On the other hand, the simplification in construction procedures could induce seepage inside the cofferdam, which additionally increased the deflection of USSPs by 10 mm on average.

• 한국인터넷방송통신학회논문지
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• 제22권3호
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• pp.171-176
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• 2022

신속한 차단 사양을 위한 통신 신호는 시스템 구성과 관계없이 NEC 2014, NEC 2017 또는 해당 UL 규격에서는 "적용되는 모든 태양광(PV) 시스템의 빠른 차단 요구사항을 지원하도록 설계한다"라고 규정되어 있다. 한편 신재생에너지 관련 국내 규정 등을 보면 각 기관에서 정한 기준이나 규정, 지침 등은 일반적이거나 해당 기관이 필요한 부분만 제정해서 운영 중이다. 이러한 것들을 태양광 시설에 적용하기에는 미흡한 점이 많아 설계, 감리자와 검사기관의 검사 기준, 검사자의 기술 수준에 따라 과도하게 설비를 하는 경우 등이 발생하고 있다. 국제적으로 통용되는 IEC 규격은 각종 시설규격을 자세히 다루고 있다. 유럽 각국에서는 IEC를 근간으로 별도의 시설 규정이 있는데, 특히 기기의 성능, 안전성 등을 상세하게 다루고 있고, 미국 등 북미에서 적용하는 'NEC Article 690'인 경우 각 항목이 매우 상세하게 기술하고 있다. 따라서 본 논문에서는 국제적으로 통용 및 현재 적용되고 있는 태양광(PV) 셧다운(Shutdown) 기술에 대한 세부 내용들을 살펴보고자 한다.

• 정보보호학회논문지
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• 제32권2호
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• pp.255-266
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• 2022

메신저 애플리케이션은 서버로 메시지 노출을 방지하고자 종단간 암호화를 자체적으로 적용하였다. 안전하고 효율적인 메시지 통신을 위해 종단간 암호화가 적용된 그룹 메시징 프로토콜인 MLS (Message Layer Security)의 표준화가 진행 중이다. 본 논문은 MLS의 동작 과정과 보안 요구사항을 기반으로 안전성 점검을 수행한다. 메신저 통신에서 필수 보안 요구사항인 중앙 서버에 대한 기밀성은 서버 관리자에 의해 쉽게 위반될 수 있다. 그룹의 통신 내용이 궁금한 서버 관리자를 curious admin으로 정의하고 관리자가 MLS에서 그룹키를 획득하는 공격을 제시한다. 메신저 애플리케이션 사용자에게 서버가 언제든 통신 내용을 열람할 수 있다는 점을 상기시킨다. Curious admin 공격을 방지하기 위해 서버를 거치지 않고 사용자 간 인증하는 방안에 대해 논의한다.

• International Journal of Computer Science & Network Security
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• 제22권5호
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• pp.103-114
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• 2022

The Internet of Things (IoT) is one of the fastest technologies that are used in various applications and fields. The concept of IoT will not only be limited to the fields of scientific and technical life but will also gradually spread to become an essential part of our daily life and routine. Before, IoT was a complex term unknown to many, but soon it will become something common. IoT is a natural and indispensable routine in which smart devices and sensors are connected wirelessly or wired over the Internet to exchange and process data. With all the benefits and advantages offered by the IoT, it does not face many security and privacy challenges because the current traditional security protocols are not suitable for IoT technologies. In this paper, we presented a comprehensive survey of the latest studies from 2018 to 2021 related to the security of the IoT and the use of machine learning (ML) and deep learning and their applications in addressing security and privacy in the IoT. A description was initially presented, followed by a comprehensive overview of the IoT and its applications and the basic important safety requirements of confidentiality, integrity, and availability and its application in the IoT. Then we reviewed the attacks and challenges facing the IoT. We also focused on ML and its applications in addressing the security problem on the IoT.