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비접촉식 화학작용제 탐지용 라만 분광계를 위한 Denoising Autoencoder 기반 잡음제거 기술
이창식,유형근,박재현,김휘민,박동조,장동의,남현우,Lee, Chang Sik,Yu, Hyeong-Geun,Park, Jae-Hyeon,Kim, Whimin,Park, Dong-Jo,Chang, Dong Eui,Nam, Hyunwoo 한국군사과학기술학회 2021 한국군사과학기술학회지 Vol.24 No.4
Raman spectrometers are studied and developed for the military purposes because of their nondestructive inspection capability to capture unique spectral features induced by molecular structures of colorless and odorless chemical warfare agents(CWAs) in any phase. Raman spectrometers often suffer from random noise caused by their detector inherent noise, background signal, etc. Thus, reducing the random noise in a measured Raman spectrum can help detection algorithms to find spectral features of CWAs and effectively detect them. In this paper, we propose a denoising autoencoder for Raman spectra with a loss function for sample efficient learning using noisy dataset. We conduct experiments to compare its effect on the measured spectra and detection performance with several existing noise reduction algorithms. The experimental results show that the denoising autoencoder is the most effective noise reduction algorithm among existing noise reduction algorithms for Raman spectrum based standoff detection of CWAs.
단일 프레임 입자 추적법을 이용한 흡입 2밸브 가솔린 기관의 실린더 내 정상 유동 해석
이창식,이기형,임경수,전문수,Lee, Chang-Sik,Lee, Gi-Hyeong,Im, Gyeong-Su,Jeon, Mun-Su 대한기계학회 1997 大韓機械學會論文集B Vol.21 No.5
Analysis and control of intake charge motion such as swirl and tumble are very important factors in improving the gasoline engine performance. In this paper, single-frame PTV (particle tracking velocimetry) is used to investigate intake tumble patterns in a steady flow test rig of gasoline engine with dual-intake-valve and pent-roof combustion chamber. Intake tumble pattern is quantified in accordance with blockage ratio of TIV (tumble intensifying valve) with single- frame PTv.The view of the instantaneous 2-D velocity field gives a realistic understanding of in-cylinder flow field. Thus it is confirmed that PTV is a effective tool in engine design. In conventional port, two tumble structures appear clearly, and the larger one is observed under the exhaust valve side and the smaller is right below the intake valve side. The larger vorticity is observed in TIV port, thus it is concluded that TIV have an effect on intensified tumble motion in cylinder flow.