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변형 스플라인 보간법(곡선맞춤)을 통한 가속도 센서의 동적 온도 보상 시스템 개발
이후창(Hoochang Lee),고재두(Jaedoo Go),유광호(Kwangho Yoo),김완일(Wanil Kim) 한국자동차공학회 2014 한국 자동차공학회논문집 Vol.22 No.3
Sensor fusion is the one of the main research topics. It offers the highly reliable estimation of vehicle movement by processing and mixing several sensor outputs. But unfortunately, every sensor has drift which degrades the performance of sensor. It means a single degraded sensor output may affect whole sensor fusion system. Drift in most research is ideally assumed to be zero because its usually a nonlinear model and has sample variation. Plus, it’s very difficult for the acceleration to separate drift from the output signal since it contains many contributors such as vehicle acceleration, slope angle, pitch angle, surface condition and so on. In this paper, modified spline interpolation is introduced as a dynamic temperature compensation method covering sample variation. Using the last known output and the first initial output is suggested to build and update compensation factor. When the system has more compensation data, the system will have better performance of compensated output because of the regression compensation model. The performance of the dynamic temperature compensation system is evaluated by measuring offset drift between with and without the compensation.
3축 가속도센서를 이용한 도로 등판각 및 횡경사각 추정 방법
이후창(Hoochang Lee),윤정운(Jeongun Yoon),김건하(Gunha Kim),유광호(Kwangho Yoo),김완일(Wanil Kim) 한국자동차공학회 2015 한국자동차공학회 학술대회 및 전시회 Vol.2015 No.11
The climbing and road bank angle are the one of the most important information for active safety systems. But unfortunately, it isn’t easy to simply calculate since the angle is estimated from 2axis accelerometer which is also including driving acceleration and lateral slip angle. So current estimation algorithm requires complex equations and many variables from other sensors in order to extract the angles from measured acceleration. In this paper, a new angle estimation method based on 3axis accelerometer has been introduced with relatively simple equations. The performance of new approach has been evaluated by measuring the calculated angles.
Hoo Chang Lee(이후창),Bo Kyung Hwang(황보경),Tae Soo Kim(김태수) Korean Society for Precision Engineering 2018 한국정밀공학회지 Vol.35 No.6
Recently, the use of stainless steels have been increased steadily as a sustainable structural material in infrastructures and thanks to its superior corrosion resistance, fire resistance and ductility compared with those of carbon steels. In this paper, block shear fracture behaviors in base metal of fillet-welded connection fabricated with austenitic stainless steel (STS304L) were investigated through monotonic tensile test. Main variables are weld lengths in the longitudinal and the transverse directions of applied force. Gas tungsten arc welding (GTAW) which is also known as tungsten inert gas (TIG) welding was chosen to join two metals. As a result, test specimens failed by typical block shear fracture (the combination of tensile fracture and shear-out fracture) in base steel. With the increase of two weld lengths, the ultimate strengths of specimens tended to get higher. Block shear fracture strengths predicted by current design specifications and existing proposed equations for welded connections were compared with those of test results. It is found that the discrepancy of strength prediction resulted from the effect of stress triaxiality on welded connections and the difference of material properties with carbon steel. Therefore, modified block shear fracture equation was suggested in this paper.