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제어기 모드 스위칭을 이용한 사이버 물리 시스템의 검지 회피 센서 공격 대응
전희균(Heegyun Jeon),은용순(Yongsoon Eun) 제어로봇시스템학회 2021 제어·로봇·시스템학회 논문지 Vol.27 No.2
This paper reports on a detection technique for stealthy sensor attacks on cyber-physical systems (CPS). The considered attack is a pole-dynamics attack, in which false data are injected to cancel the unstable trajectory of a plant captured on the feedback sensor output. In this attack, the systems appear to operate normally in the steady-state while the plant is destabilized. The target system is a linear plant, including unstable pole-dynamics, and we assume that the adversary knows the model to carry out the attack. The proposed detection method employs a switching mechanism of two control modes that play different roles. The first mode is the normal mode, which consists of a linear controller and an anomaly detector, having the same structure as those used in conventional networked control systems. The second mode is the attack detection mode, which utilizes an internal feedback controller. It is assumed that this internal controller is not known to the adversary. When the system is in the attack detection mode, owing to the use of the internal controller, the overall system dynamics differ from those adopted by the adversary, thereby the effect of the attack is revealed. The CPS periodically switches between the attack detection mode and normal mode. The timing of the switch is determined to ensure that any attack is revealed before the physical system becomes unstable. The results are validated via simulations of quadrotor control.
심장조직 정밀분석을 위한 고주파 초음파 횡파 탄성 영상 시스템
이승엽(Seungyeop Lee),은영민(Lucy Youngmin Eun),황재윤(Jae Youn Hwang),은용순(Yongsoon Eun) 한국비파괴검사학회 2021 한국비파괴검사학회지 Vol.41 No.4
심장질환 진단을 위한 다양한 영상 장치가 있지만 작은 병변 또는 경미한 단계의 질환을 발견하는 것은 어렵다. 본 연구에서는 심장질환에 의한 미세한 심장 조직 변화를 분석할 수 있는 고주파 초음파 횡파영상 시스템을 제안한다. 제안된 시스템은 작은 병변을 감지할 수 있도록 높은 해상도의 영상을 얻기 위하여 38 MHz 초음파 변환자를 제작 이용하였고, 조직 내의 충분한 횡파의 발생을 위해 기계적 진동기를 사용하였다. 시스템의 성능 확인을 위해 팬텀을 이용하여 심장의 횡 방향 / 축 방향 분해능을 측정하였고, 해상도는 각각 144 μm와 168 μm가 측정되었다. 시스템의 유효성 확인을 위해 돼지 심장을 이용한 체외 실험을 수행하였다. 돼지 심장 실험은 정상 심장 조직을 국소적으로 냉각 및 가열시킨 후 실험하였고, 본 시스템으로 심장조직의 국소적 변화를 관찰할 수 있었다. 따라서 향후 본 연구에서 제안하는 영상 시스템을 적용한 임상연구를 거쳐 심장질환 조기진단이 가능하게 될 것이다. Several imaging devices have been used to diagnose heart disease. However, these imaging devices have limitations with regard to the observation of small lesions, which makes early detection of heart disease difficult. This study proposes a shear wave imaging system with a high-frequency ultrasound transducer to measure the mechanical properties of heart tissue to diagnose heart disease. A 38-MHz ultrasound transducer is used to achieve a high-resolution image, and a mechanical vibrator is used to generate shear waves in the heart tissue. In the phantom experiments, spatial resolutions are experimentally determined. The lateral and axial resolutions are 144 and 168 μm, respectively. The feasibility of the proposed system is demonstrated in the experiments pertaining to induced disease-like deformations. The obtained images exhibit local variations in the mechanical properties. Thus, the proposed imaging system can detect small lesions in heart tissue, which is important for early detection of heart disease.
열차 제어 시스템을 위한 자동 진단 및 실시간 모니터링 소프트웨어
서동진(Dong-Jin Suh),박재근(Jaegeun Park),원유창(Yuchang Won),은용순(Yongsoon Eun) 제어로봇시스템학회 2021 제어·로봇·시스템학회 논문지 Vol.27 No.3
Train control systems consist of supervisory controller, network, and multiple trains. Actual trains are controlled and supervised by computer based signals, which put this system in the paradigm of CPS (Cyber-Physical Systems). Recent trends in train control systems are adopting wireless communication protocols to improve operational efficiency. While efficiency is improved by overcoming legacy fixed block based operation, wireless communication channels open new surfaces for external attack and malfunction. Actual attacks on CPS indeed have been materialized in trains, and as a result, attention from academia and industry for resiliency for train control systems are increasing. This manuscript overviews the trend and latest effort to this regard and introduces status of train control software that enhances the aspect of automatic diagnosis and real-time monitoring features.