• 분석과학
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• 제22권3호
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• pp.235-246
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• 2009

제조 공장의 구분이 가능한지 검토하기 위하여 LA-ICP-MS를 이용한 한국 자동차 전면 유리의 미량원소 분석을 실시하였다. 먼저 Si를 내부 표준물질로 하여 표준품 NIST 610, 612, 614과 616을 분석하여 검량선을 작성하였다. 시료와 표준품은 24원소에 대해 정량을 실시하였고 LOQ는 0.11 mg/kg(Ti)-4.91 mg/kg(Ca) 였다. 2개 공장의 11개 시료에 대하여 각각 5개씩의 위치에 따른 부시료를 분석하였다. 검출한계이하의 원소들(Cu, Cr, Cd와 Ni), 표준품에 존재하지 않는 원소들(Ti, Pr, Mg, Nb, Nd)과 균질성에 문제가 있는 원소들(Pb와 Sn)은 분석 대상 원소에서 제외하였다. 제조공장과 제조년도와 관련하여 삼각 다이어그램을 그려 본 결과 구별의 가능성을 볼 수 있었으며 Mn, Ce와 Rb를 토대로 한 정준 판별 분석식에 의해 제조공장의 구별이 가능하였다.

• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2023년도 추계학술발표대회
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• pp.252-256
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• 2023

쇼어 알고리즘을 실행할 수 있는 양자 컴퓨터의 발전으로 인해 기존 ECC(Elliptic Curve Cryptography)를 사용하던 블록체인이 PQC(Post Quantum Cryptography)로의 전환을 고려하고 있다. 하지만 PQC 는 기존 암호에 비해 큰 사이즈, 느린 서명/검증 속도 등과 같은 문제점이 존재한다. 본 논문에서는 우리가 WISA'23 에서 새롭게 제안한 PQ-DPoL 합의 알고리즘에 NIST(National Institute of Standards and Technology)가 선정한 Crystal-Dilithium, Falcon 그리고 Sphincs+를 적용하여 비교 분석하였다. 실험 결과에 따르면, 매우 큰 서명 크기를 가지고 있기 때문에 블록에 담기는 트랜잭션의 수가 감소하므로 Sphincs+의 성능이 가장 떨어짐을 확인하였다. 또한 Dilithium 은 Falcon 과 비슷한 성능을 보여주었다. 그 중에서도 Falcon 이 가장 우수한 성능을 보여주었다. 이는 Falcon 의 공개키와 서명의 크기가 다른 알고리즘에 비해 작기 때문이다. 따라서 양자내성을 갖는 블록체인에는 Falcon 512 알고리즘이 가장 적합할 것으로 생각된다. 그러나 블록체인의 속도와 보안 강도는 Trade-off 관계이므로 보안성을 중요시하는 블록체인 네트워크에서는 Sphincs+가 적합할 수 있을 것으로 보인다. 따라서 블록체인 네트워크의 상황과 목적에 따라 적절한 알고리즘을 사용해야 될 것으로 생각된다.

• Journal of Radiation Protection and Research
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• 제44권2호
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• pp.72-78
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• 2019

Background: In the calibration and testing laboratory of Korea Atomic Energy Research Institute, the old X-ray generator used for the production of reference X-ray fields was replaced with a new one. For this newly installed X-ray irradiation system, beam alignment as well as the verification of beam qualities was conducted. Materials and Methods: The existing X-ray generator, Phillips MG325, was replaced with YXLON Y.TU 320-D03 in order to generate reference X-ray fields. Theoretical calculations and Monte Carlo simulations were used to determine initial filter thickness. Beam alignment was performed in three steps to deliver a homogeneous radiation dosage to the target at different distances. Finally, the half-value layers were measured for different X-ray fields to verify beam qualities by using an ion chamber. Results and Discussion: Beam alignment was performed in three steps, and collimators and other components were arranged to maintain the uniformity of the mean air kerma rate within ${\pm}2.5%$ at the effective beam diameter of 28 cm. The beam quality was verified by using half-value layer measurement methods specified by American National Standard Institute (ANSI) N13.11-2009 and International Organization for Standardization (ISO)-4037. For each of the nine beams than can be generated by the new X-ray irradiation system, air kerma rates for X-ray fields of different beam qualifies were measured. The results showed that each air kerma rate and homogeneity coefficient of the first and second half-value layers were within ${\pm}5%$ of the recommended values in the standard documents. Conclusion: The results showed that the new X-ray irradiation system provides beam qualities that are as high as moderate beam qualities offered by National Institute of Standards and Technology in ANSI N13.11-2009 and those for narrow-spectrum series of ISO-4037.

• Steel and Composite Structures
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• 제10권2호
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• pp.129-149
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• 2010

The objective of this study is to formulate a general 3D material-structural analysis framework for the thermomechanical behavior of steel-concrete structures in a fire environment. The proposed analysis framework consists of three sequential modeling parts: fire dynamics simulation, heat transfer analysis, and a thermomechanical stress analysis of the structure. The first modeling part consists of applying the NIST (National Institute of Standards and Technology) Fire Dynamics Simulator (FDS) where coupled CFD (Computational Fluid Dynamics) with thermodynamics are combined to realistically model the fire progression within the steel-concrete structure. The goal is to generate the spatial-temporal (ST) solution variables (temperature, heat flux) on the surfaces of the structure. The FDS-ST solutions are generated in a discrete form. Continuous FDS-ST approximations are then developed to represent the temperature or heat-flux at any given time or point within the structure. An extensive numerical study is carried out to examine the best ST approximation functions that strike a balance between accuracy and simplicity. The second modeling part consists of a finite-element (FE) transient heat analysis of the structure using the continuous FDS-ST surface variables as prescribed thermal boundary conditions. The third modeling part is a thermomechanical FE structural analysis using both nonlinear material and geometry. The temperature history from the second modeling part is used at all nodal points. The ABAQUS (2003) FE code is used with external user subroutines for the second and third simulation parts in order to describe the specific heat temperature nonlinear dependency that drastically affects the transient thermal solution especially for concrete materials. User subroutines are also developed to apply the continuous FDS-ST surface nodal boundary conditions in the transient heat FE analysis. The proposed modeling framework is applied to predict the temperature and deflection of the well-documented third Cardington fire test.

• Journal of Positioning, Navigation, and Timing
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• 제12권4호
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• pp.437-445
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• 2023

A space system refers to a network of sensors, ground systems, and space-craft operating in space. The security of space systems relies on information systems and networks that support the design, launch, and operation of space missions. Characteristics of space operations, including command and control (C2) between space-craft (including satellites) and ground communication, also depend on wireless frequency and communication channels. Attackers can potentially engage in malicious activities such as destruction, disruption, and degradation of systems, networks, communication channels, and space operations. These malicious cyber activities include sensor spoofing, system damage, denial of service attacks, jamming of unauthorized commands, and injection of malicious code. Such activities ultimately lead to a decrease in the lifespan and functionality of space systems, and may result in damage to space-craft and, lead to loss of control. The Cybersecurity Adversarial Tactics, Techniques, and Common Knowledge (ATT&CK) matrix, proposed by Massachusetts Institute of Technology Research and Engineering (MITRE), consists of the following stages: Reconnaissance, Resource Development, Initial Access, Execution, Persistence, Privilege Escalation, Defense Evasion, Credential Access, Discovery, Lateral Movement, Collection, Command & Control, Exfiltration, and Impact. This paper identifies cybersecurity activities in space systems and satellite navigation systems through the National Institute of Standards and Technology (NIST)'s standard documents, former U.S. President Trump's executive orders, and presents risk management activities. This paper also explores cybersecurity's tactics attack techniques within the context of space systems (space-craft) by referencing the Sparta ATT&CK Matrix. In this paper, security threats in space systems analyzed, focusing on the cybersecurity attack tactics, techniques, and countermeasures of space-craft presented by Space Attack Research and Tactic Analysis (SPARTA). Through this study, cybersecurity attack tactics, techniques, and countermeasures existing in space-craft are identified, and an understanding of the direction of application in the design and implementation of safe small satellites is provided.

• 한국항공우주학회지
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• 제43권12호
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• pp.1108-1115
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• 2015

본 연구에서는 마우스피스 방법을 이용하여 산소의 질량유량 측정과 헬륨의 체적유량 측정에 대한 관계식을 정리하였다. 마우스피스 방법은 상사된 실험식을 이용함으로써 시험비용을 절감할 수 있다. 마우스피스 방법에서는 기체헬륨을 측정하여 용이하게 액체산소의 누설량을 측정할 수 있다. 시제품의 누설량 측정에서 상온과 극저온 상태의 헬륨과 산소간의 누설량 관계를 이해하기 위해 실험을 수행하여 비교하였다. 헬륨의 누설 체적유량[$A.m{\ell}/s$]은 액체상태의 산소 누설의 질량유량[g/s]에 대비하여 174배였다. 실험식과 비교된 계산식은 미국 국립기술표준원의 자료를 이용하여 증명하였다.

• 한국광학회지
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• 제15권5호
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• pp.443-448
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• 2004

국제단위계 중의 하나인 칸델라 눈금을 두 개의 광도계를 사용하여 실현하였다. 광도계의 분광감응도는 광출력을 전기출력으로 치환하여 측정하는 극저온 절대복사계에 소급하여 측정하였다. 광도계 외부에 설치된 정밀 개구는 다이아몬드 회전가공기로 가공하였으며 그 면적은 불확도 0.05%(k = 1) 이내로 측정하였다. 이 광도계를 사용하여 광도 벤치 위에서 1 kW FEL 전구로 칸델라 단위를 실현할 때 불확도를 분광감응도, 감응도의 공간 균일도, 개구 면적, FEL 전구의 색온도와 위치 재현성을 고려하여 평가한 결과 0.25%(k = 1)를 얻었다. 실현한 눈금의 유효성을 확인하기 위하여 미국 NIST의 눈금과 비교한 결과 0.1% 이내에서 일치하였다.

• 한국정보통신학회논문지
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• 제15권1호
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• pp.115-125
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• 2011

해쉬함수는 데이터와 명령에 대한 위변조를 방지와 같은 무결성 제공하거나 서명이나 키 분배 등 다양한 보안 프로토콜에서 서명 및 인증, 키 분배 목적으로 많이 사용되는 일방향성 함수(one-way function)다. 2005년 Wang에 의해 암호학적 취약성이 발견되기까지 해쉬함수로는 SHA-1이 많이 사용 되었다. SHA-1의 안전성에 문제가 생기게 되자 NIST(National Institute of Standards and Technology)에서는 암호학적으로 안전한 새로운 해쉬함수 개발 필요성을 느껴 2007년 11월에 공개적으로 새로운 해쉬함수에 대한 공모를 시작했으며, SHA-3로 명명된 새로운 해쉬함수는 2012년 최종 선정될 예정이다. 현재 제안된 SHA-3 함수들에 대한 암호학적인 특성과 하드웨어로 구현했을 때의 하드웨어 복잡도, 소프트웨어로 구현했을 때의 성능 등에 대한 평가가 이뤄지고 있다. 하지만 하드웨어로 구현된 해쉬함수의 중요한 특성 평가 척도(metrics)인 소비 전력 특성에 대한 연구는 활발히 이뤄지지 않고 있다. 본 논문에서는 제안된 SHA-3 해쉬함수를 하드웨어로 구현했을 경우의 소비 전력 특성을 분석하고 소비전력 특성 분석 결과를 토대로 SHA-3 해쉬함수 중에서 새로운 SHA-3 해쉬함수로 선정될 확률이 높은 Luffa 함수에 대한 저전력 구조를 제안한다. 제안된 저전력 구조는 기존의 Luffa 하드웨어보다 약 10% 정도 적은 전력을 소비함을 보인다.

• Journal of Information Technology Applications and Management
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• 제26권5호
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• pp.13-25
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• 2019

Recently, as evaluation of information security (IS) management become more diverse and complicated, the contents and procedure of the evidence to prepare for actual assessment are rapidly increasing. As a result, the actual assessment is a burden for both evaluation agencies and institutions receiving assessments. However, most of them reflect the evaluation system used by foreign government agencies, standard organizations, and commercial companies. It is necessary to consider the evaluation system suitable for the domestic environment instead of reflecting the overseas evaluation system as it is. The purpose of this study is as follows. First, we will present the problems of the existing information security assessment system and the improvement direction of the information security assessment system through analysis of existing information security assessment system. Second, it analyzes the technical guidance for information security testing and assessment and the evaluation of information security management in the Special Publication 800-115 'Technical Guide to Information Security Testing and Assessment' of the National Institute of Standards and Technology (NIST). Third, we will build a framework to implement the evidence collection system and present a system implementation method for the '6. Information System Security' of 'information security management actual condition evaluation index'. The implications of the framework development through this study are as follows. It can be expected that the security status of the enterprises will be improved by constructing the evidence collection system that can collect the collected evidence from the existing situation assessment. In addition, it is possible to systematically assess the actual status of information security through the establishment of the evidence collection system and to improve the efficiency of the evaluation. Therefore, the management system for evaluating the actual situation can reduce the work burden and improve the efficiency of evaluation.

• Nuclear Engineering and Technology
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• 제54권9호
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• pp.3317-3323
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• 2022

Half Value Layer calculations theoretically need prior specification of linear attenuation calculations, since the HVL value is derived by dividing ln(2) by the linear attenuation coefficient. The purpose of this study was to establish a direct computational model for determining HVL, a vital parameter in nuclear radiation safety studies and shielding material design. Accordingly, a typical gamma-ray transmission setup has been modeled using MCNPX (version 2.4.0) general-purpose Monte Carlo code. The MCNPX code's INPUT file was designed with two detection locations for primary and secondary gamma-rays, as well as attenuator material between those detectors. Next, Half Value Layer values of some well-known gamma-ray shielding materials such as lead and ordinary concrete have been calculated throughout a broad gamma-ray energy range. The outcomes were then compared to data from the National Institute of Standards and Technology. The Half Value Layer values obtained from MCNPX were reported to be highly compatible with the HVL values obtained from the NIST standard database. Our results indicate that the developed INPUT file may be utilized for direct computations of Half Value Layer values for nuclear safety assessments as well as medical radiation applications. In conclusion, advanced simulation methods such as the Monte Carlo code are very powerful and useful instruments that should be considered for daily radiation safety measures. The modeled MCNPX input file will be provided to the scientific community upon reasonable request.