http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Pixel-wise distortion model and its calibration method for AMCW LiDAR
Junwoo Jason Son,Youngbin Son,Byeongho Song,Soohee Han 제어로봇시스템학회 2021 제어로봇시스템학회 국제학술대회 논문집 Vol.2021 No.10
In this conference paper, we proposed pixel-wise distortion model and its calibration method for AMCW (Amplitude Modulated Continuous Wave) LiDAR (Light Detection and Ranging). The proposed model can be reflect square wave distortion, common mode error and non-linear characteristic of the receiving circuit. The model characterise the distance error with actual distance and amplitude of the DCS (Differential Correlation Sample). A simple calibration method is also announced in order to use the proposed model. The method uses modulation signal delay and shutter speed variation to measure the response of the receiving circuit. The experiment was carried out with various signal delay and shutter speed under simple calibration box. The result shows the response of the AMCW LiDAR was changed by both inputs and also the AMCW LiDAR can measure the distance without these errors by using the proposed model and calibration method.
Spray Patterns and Injection Characteristics of Gas-Centered Swirl Coaxial Injectors
Son, Jinwoo,Sohn, Chae Hoon,Park, Gujeong,Yoon, Youngbin American Society of Civil Engineers 2017 Journal of aerospace engineering Vol.30 No.5
<P>Spray characteristics of gas-centered swirl coaxial injectors, which are commonly used in staged combustion cycle engines, are investigated numerically and experimentally. The spray angle and the spreading angle are the quantitative parameters selected for experimental and numerical studies, respectively. Various gas/liquid Reynolds numbers are adopted for the operating conditions. For a fixed gas Reynolds number, the spreading angle increases with the liquid Reynolds number. Through the comparative study of the spray angle from water/air experiments, the spreading angle is analyzed for different momentum flux ratios (MFRs). The comparison of the spray and spreading angles for different MFRs shows good agreement. Modeling and study of gas-gas flow is a useful approach to understanding spray characteristics of gas-liquid flow. (C) 2017 American Society of Civil Engineers.</P>
Cho, Youngbin,Son, Minjeong,Jeong, Hyuntae,Shin, Jennifer H. American Society for Cell Biology 2018 Molecular biology of the cell Vol.29 No.19
<P>During wound healing, cells migrate with electrotactic bias as a collective entity. Unlike the case of the electric field (EF)-induced single-cell migration, the sensitivity of electrotactic response of the monolayer depends primarily on the integrity of the cell–cell junctions. Although there exist biochemical clues on how cells sense the EF, a well-defined physical portrait to illustrate how collective cells respond to directional EF remains elusive. Here, we developed an EF stimulating system integrated with a hydrogel-based traction measurement platform to quantify the EF-induced changes in cellular tractions, from which the complete in-plane intercellular stress tensor can be calculated. We chose immortalized human keratinocytes, HaCaT, as our model cells to investigate the role of EF in epithelial migration during wound healing. Immediately after the onset of EF (0.5 V/cm), the HaCaT monolayer migrated toward anode with ordered directedness and enhanced speed as early as 15 min. Cellular traction and intercellular stresses were gradually aligned perpendicular to the direction of the EF until 50 min. The EF-induced reorientation of physical stresses was then followed by the delayed cell-body reorientation in the direction perpendicular to the EF. Once the intercellular stresses were aligned, the reversal of the EF direction redirected the reversed migration of the cells without any apparent disruption of the intercellular stresses. The results suggest that the dislodging of the physical stress alignment along the adjacent cells should not be necessary for changing the direction of the monolayer migration.</P>
화염 전달함수 및 DMD 기법을 이용한 모형 가스터빈의 연소불안정성 평가
손진우(Jinwoo Son),손채훈(Chae Hoon Sohn),윤지수(Jisu Yoon),윤영빈(Youngbin Yoon) 한국연소학회 2017 한국연소학회지 Vol.22 No.2
To evaluate the combustion instability of a gas turbine combustor, the DMD technique was applied. The mode frequency results for each fuel composition were compared with FFT(Fast Fourier Transform) results. The damping coefficient, which is a quantitative parameter for combustion instability, was evaluated for 5 experimental cases. The flame transfer function (FTF) was calculated in the most unstable test case. In deriving the FTF, gain and phase were calculated using DMD technique. As a result of the analysis of the OH radical perturbation of the DMD, the heat release fluctuation was the highest at 100 Hz, at which the highest value of gain is observed. The frequency of FFT and FTF were different. In order to clarify the reason for this, FTF for various resonance frequencies was performed and it shows that the pattern of gain was similar to FFT.