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김동국(Dongguk Kim),윤형주(Hyungjoo Yoon),진재현(Jaehyun Jin) 한국항공우주학회 2013 韓國航空宇宙學會誌 Vol.41 No.10
본 논문에서는 반구형 공진자이로에 대한 연구를 위해 NI FPGA 장비를 기반으로 한 실험 장치를 개발하였고 공진유도, 진폭제어 및 회전실험을 통해 실험 장치에 대한 적합성을 판별하고 시스템에 대한 파라미터를 추정하였다. 또한 공진기의 형상 불 균일로 인해 진동패턴이 표류하는 현상을 확인하고, 이를 정렬시킴으로써 구동모드중 하나인 FTR 모드 구현에 대한 선행연구를 수행하였다. The authors have developed a test system for a hemispherical resonator gyroscope by using NI FPGA equipment. We have verified its suitability for the research of resonator gyroscopes through several tests: deriving resonance, controlling amplitudes, and estimating resonator parameters. The authors have adjusted a vibrating pattern to be aligned with the driving axis (or electromagnets). This pattern alignment is a basic and important operation of the FTR mode, which is one of operating modes for resonant gyroscopes.
김동국(DongGuk Kim),장성용(SeongYong Jang),이원영(WonYoung Lee),김용호(YongHo Kim),박창현(Changhyun Park) 한국정보보호학회 2009 정보보호학회논문지 Vol.19 No.5
포렌식 수사 절차상의 무결성을 입증하기 위한 방안으로 해쉬 함수 알고리즘을 적용한 디지털 증거의 경우, 무결성이 손상되면 그 자료는 폐기되어야만 했다. 즉, 주요 사건의 핵심 부분에 대한 증거 확보를 위해서는 삭제 영역에 대한 증거 복원이 필수적임에도 불구하고, 전체적인 해쉬값이 처음 해쉬값과 달라 증거 데이터가 훼손됨으로 인하여 결정적인 증거 능력 확보에 어려움이 있었다. 본 논문에서는 이와 같은 문제점을 해결하기 위한 방안으로서 새로운 모바일 포렌식 절차 모델인 Evidence-Finder (이하 E-Finder) 모바일 포렌식 절차 모델 을 제안한다. E-Finder 절차는 5개 영역의 총 15개 절차 모델로 구성되며 E-Finder 절차를 기존 NIST(National Institute of Standards and Technology)모델, Tata Elxsi Security Group 모델과 비교 및 고찰하였다. 이로 인하여, 현재까지 모바일 포렌식 분야에서 표준화 되지 않고, 검증되지 않은 방법론을 개선하는 기대효과를 달성하였다. To prove the integrity of digital evidence on the investigation procedure, the data which is using the MD 5(Message Digest 5) hash-function algorithm has to be discarded, if the integrity was damaged on the investigation. Even though a proof restoration of the deleted area is essential for securing the proof regarding a main phase of a case, it was difficult to secure the decisive evidence because of the damaged evidence data due to the difference between the overall hash value and the first value. From this viewpoint, this paper proposes the novel model for the mobile forensic procedure, named as E-Finder(Evidence Finder) , to solve the existing problem. The E-Finder has 5 main phases and 15 procedures. We compared E-Finder with NIST(National Institute of Standards and Technology) and Tata Elxsi Security Group. This paper thus achieved the development and standardization of the investigation methodology for the mobile forensics.
진재현(Jaehyun Jin),김동국(Dongguk Kim) 제어로봇시스템학회 2014 제어·로봇·시스템학회 논문지 Vol.20 No.5
This article focuses on a hemispherical resonator gyro driven by the Coriolis effect. A hemispherical shell, called a resonator, is maintained in the resonance state by amplitude control and phase locking control. Parametric excitation has been used to control the amplitude. For rate measurement mode or FTR mode, nodal points have been kept to an amplitude of zero. Angular rate measurement has been demonstrated by rotating a resonator. Frequency mismatch between two stiffness principal axes is a major cause of low performance: vibrating pattern drift and reduced control effectiveness. This mismatch has been reduced significantly by the addition of small mass. A negative spring effect, which lowers resonance frequencies, has been verified experimentally.
진재현(Jaehyun Jin),최홍택(Hong-taek Choi),윤형주(Hyungjoo Yoon),김동국(Dongguk Kim),Sergii Sarapulov 제어로봇시스템학회 2013 제어·로봇·시스템학회 논문지 Vol.19 No.10
This article focuses on a hemispherical resonator gyro driven by the Coriolis effect. The operational principle of resonator gyros and mathematical models are introduced. These models are useful to explain the behavior of a resonator and to design controllers. Several control tests of a resonator have been done. A resonator has been excited by electromagnets controlled by a computer. Its amplitude has been adjusted by a PI control. The transient response is matched with a simulation result based on a mathematical model. A vibrating pattern may drift due to non-uniform factors of a resonator. The drift of the vibrating pattern is controlled and aligned to a reference direction by a PI control. These results are very useful to understand the behavior of resonator gyros and to design advanced control algorithm for better performance.