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MODEL-BASED SENSOR FAULT DIAGNOSIS OF VEHICLE SUSPENSIONS WITH A SUPPORT VECTOR MACHINE
Kicheol Jeong,Seibum Choi 한국자동차공학회 2019 International journal of automotive technology Vol.20 No.5
In this paper, a means of generating residuals based on a quarter-car model and evaluating them using a support vector machine (SVM) is proposed. The proposed model-based residual generator shows very robust performance regardless of unknown road surface conditions. In addition, an SVM classifier without empirically set thresholds is used to evaluate the residuals. The proposed method is expected to reduce the effort required to design fault diagnosis algorithms. While an unknown input observer is used to generate the residual, the relative velocity of the vehicle suspension is obtained additionally. The proposed algorithm is verified using commercial vehicle simulator Carsim with Matlab & Simulink. As a result, the fault diagnosis algorithm proposed in this paper can detect sensor faults that cannot be detected by a limit checking method and can reduce the effort required when designing algorithms.
MR 댐퍼의 상대속도 추정을 위한 Takagi-Sugeno 퍼지 관측기 개발
정기철(Kicheol Jeong),최세범(Seibum Choi),이준명(Junmyung Lee),김현태(Hyuntae Kim) 한국자동차공학회 2019 한국자동차공학회 부문종합 학술대회 Vol.2019 No.5
In this paper, the Takagi-Sugeno (T-S) fuzzy observer is proposed to estimate the relative velocity of magnetorheological (MR) damper. MR damper has highly nonlinear dynamics therefore the linear observer design method cannot be adopted. Therefore, T-S modeling technique such as sector nonlinearity is used to design T-S fuzzy model. The T-S model is developed from the experimental dataset. This paper uses two MR damper models. First, the phenomenological model is used as a plant. This model is used to build the damper force for vehicle simulator Carsim. Next, the bouc-wen model is used to design T-S fuzzy observer. This paper proposes T-S fuzzy observer which has unmeasured premise variables. To verify the stability of this observer, Lyapunov stability theorem is used. The proposed observer is verified to vehicle simulator Carsim and Matlab/Simulink. Consequently, this paper proposed the relative velocity estimator which has robustness to unknown road input.
딥러닝을 활용한 전기자동차 감속기 베어링의 고장 특징 추출
정기철(Kicheol Jeong),문철우(Chulwoo Moon),진효민(Hyomin Jin) 한국자동차공학회 2022 한국자동차공학회 부문종합 학술대회 Vol.2022 No.6
Recently, an EV (electric vehicle) is the key word of world-wide vehicle industry. The EV is actuated by a traction motor. In order to adjust a torque of the traction motor, a gearbox is necessary part of the EV. The gearbox consists of gears, bearings, and shafts. Especially, the input shaft bearings are subjected to several tons of axial load. Therefore, the fault caused by axial load in bearings has a negative impact on driving quality and vehicle safety. Consequently, the bearing fault diagnosis method is necessary especially EV power train system. In this paper, the gearbox fault feature extraction method is proposed. The proposed method constitutes a training part and an implementation part. In the training part, two accelerometers are used to implement adaptive noise cancellation algorithm. Using this preprocessed signal, supervised learning is conducted. In the implementation part, only one accelerometer is used. Consequently, the pre-trained deep learning architecture generates enhanced signal and fault features are extracted. In order to validate the proposed method, experiments using power-train dynamometer is conducted.
멀티 모델 추정기를 활용한 3륜 틸팅 차량의 노면 경사각 추정
정기철(Kicheol Jeong),최세범(Seibum Choi) 한국자동차공학회 2018 한국자동차공학회 부문종합 학술대회 Vol.2018 No.6
This paper introduces the road angle observer. In this paper, the estimator that combines a kinematic model with a dynamic model of a three wheel vehicle is proposed. The dynamic model has four states, including lateral velocity, yaw rate, tilt angle, and tilt angle ratio. Likely, kinematic model has two states, including roll and pitch angles. According to the models, Kalman filter is used to estimate vehicle lateral speed, vehicle roll and pitch angle. To verify this proposed algorithm, simulation verification using Carsim ADAMS and Matlab&Simulink is performed and a discussion of the result is provided. In addition, this paper proposes a semi-active tilt system.
저 비트율 비디오를 위한 효과적인 후처리 기법 및 성능 평가
전기철(Kicheol Jeon),김종호(Jongho Kim),정제창(Jechang Jeong) 한국방송·미디어공학회 2005 한국방송공학회 학술발표대회 논문집 Vol.2005 No.-
본 논문에서는 인터넷 스트리밍 및 모바일 응용 등에서 요구되는 저 비트율 비디오를 위한 효과적인 후처리 기법을 제안한다. 블록기반 압축영상의 특성상 낮은 비트율에서는 블록킹 현상과 같은 화질열화가 불가피하다. 이러한 블록기반 압축영상의 블록킹 현상에 대하여 본 논문에서 제안한 디블록킹 기법은 블록 경계 주변의 특성에 따라 필터링 모드를 달리 적용하여 효율적으로 블록킹 현상을 제거함으로서 주관적, 객관적 화질을 향상시킨다. 제안한 알고리즘에서는 모드 선택의 정확성을 높이기 위하여 저역통과필터를 이용한 간단한 전처리 과정을 거치도록 하고, 또한 영상의 실제 에지와 블록킹 현상을 구분하기 위하여 3가지 모드를 도입하며, 이를 통해 필터링에 의한 실제 에지 부분의 화질열화를 방지하도록 한다. 마지막으로 comer outlier와 같은 특수한 artifact의 제거를 위해 별도의 모드를 추가한다. 실험에서는 MPEG-4로 복호된 영상에 대하여 제안한 필터를 적용하고, 최근 표준화가 완료된 H.264의 루프필터 및 최근 발표된 저 비트율 비디오에 대한 후처리 기법과의 비교실험을 통하여 제안된 방법의 성능을 평가한다.
Lee, Jeong-Ho,Lee, Kicheol,Lee, Da Hyun,Shin, Soon Young,Yong, Yeonjoong,Lee, Young Han 한국응용생명화학회 2015 Applied Biological Chemistry (Appl Biol Chem) Vol.58 No.4
The invasive potential of malignant tumor cells is critical for their metastasis. This study was undertaken to evaluate the anti-invasive activity of ${\beta}$-myrcene, a natural compound found in the essential oil from Pinus koraiensis cones (EOPC), in metastatic MDA-MB-231 human breast cancer cells. Among four major constituents that included ${\alpha}$-pinene, ${\beta}$-myrcene, 3-carene, and d-limonene, ${\beta}$-myrcene showed the most potent inhibition of tumor necrosis factor-${\alpha}$ ($TNF{\alpha}$)-induced nuclear factor ${\kappa}B$ (NF-${\kappa}B$) activity. Pretreatment with ${\beta}$-myrcene suppressed $TNF{\alpha}$-induced phosphorylation of inhibitor of ${\kappa}B$ kinase and NF-${\kappa}B$ as well as matrix metalloproteinase-9 (MMP-9) gene expression in a dose-dependent fashion. Furthermore, ${\beta}$-myrcene inhibited $TNF{\alpha}$-induced invasion of MDA-MB-231 cells as determined by three-dimensional spheroid invasion assays. These findings suggest that EOPC may promote anti-metastatic activity in breast cancer cells through its downregulation of NF-${\kappa}B$-mediated MMP-9 expression.
이기철(Kicheol Lee),김동욱(Dongwook Kim),박정준(Jeong-Jun Park) 한국지반신소재학회 2017 한국지반신소재학회 논문집 Vol.16 No.2
도심지가 고도화되고 지상 공간이 포화됨에 따라 지하공간 개발 및 활용이 활발히 이루어지고 있다. 이와 동시에 지반함몰 현상, 각종 지하공간 사고 등으로 시민들의 안전이 위협받고 있다. 지반함몰을 방지하기 위하여 지하에 발생한 공동을 탐지하고 공동등급을 설정하여 공동복구 순서 및 위험도를 평가해야 한다. 기존의 일본 간선도로 공동관리 등급은 일본 현지의 기준을 대상으로 하여 국내 지반실정에 적용하기가 적합하지 않다. 최근 국내 실정에 맞게 서울형에서 공동관리 등급이 개발되었으며, 도로 하부지반 및 아스콘 포장층의 상태 등을 추가로 고려하여 공동의 등급을 지정하였다. 본 연구에서는 ○○지역를 대상으로 209개의 공동을 탐사하고, 공동 등급에 따른 공동의 형상을 분석하였다. 또한 일본의 간선도로 공동관리 등급과 새롭게 개발된 서울형 공동관리 등급으로 분류된 결과를 상호 비교하였다. 비교 분석 결과, 일본 간선도로 공동관리 등급기준으로 긴급복구로 분류되 공동들은 상당히 보수적으로 평가되었으며, 이는 일본의 기준이 도로 포장층 두께를 고려하지 않고, 공동의 폭과 토피만을 고려하였기 때문이다. Due to the rapid development of cities, densities and heights of urban structures are increased, and much larger and more underground spaces are being developed accordingly. Increasing development of underground spaces has induced more ground sinks and underground cavities. Therefore, safety of people is threatened by potential ground collapses and possible accidents, which may result from underground cavity. To actively respond against potential danger of ground sink, evaluation of existing cavity grade and development of recovery procedure are important. There exists the ground sinking management grade system of expressway developed as local standards in Japan. Recently, ground sinking management grade system of Seoul was developed with consideration of road and asphalt conditions. In this study, 209 underground cavities of ○○ area were explored and their cavity shapes and grades were evaluated based on both ground sinking management grade systems of Japan and Seoul. Comparison is made between cavity grades evaluated based on both grading systems from Japan and Seoul. As a result of comparative analysis, the conservatively-estimated cavity grades requiring emergency restoration based on the Japanese management grade system of expressway result from neglection of layer thickness of surface pavement, considering only width and cover depth of a cavity.