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정성필(Sung Pil Jung),박태원(Tae Won Park),김욱현(Wook Hyeon Kim),홍요선(Yo Sun Hong) Korean Society for Precision Engineering 2010 한국정밀공학회지 Vol.27 No.3
The pretensioner is used to retract the belt webbing and tighten up any slack in the event of a crash. The retracting force of the pretensioner helps move the passenger into the optimum crash position in his or her seat. In this paper, the new concept of an operating mechanism of the pretensioning system is presented. The internal gear design program is developed using MATLAB. Two kinds of numerical analysis model are created. The first one, the rigid body dynamic model, is used to estimate the performance of several gear pairs. The initial performance of the new operating mechanism is analyzed and the best combination of the gear pairs is selected. The second one, the structural dynamic model, is used to calculate the deformation of the gear teeth. To decrease the deformation and interference of the teeth, the shape of the gear pairs is changed.
고속 제동 시 브레이크 시스템 성능의 영향 인자에 대한 분석
정성필(Sung Pil Jung),박형배(Hyung Bae Park) 한국자동차공학회 2018 한국 자동차공학회논문집 Vol.26 No.2
In this paper, sensitivity analysis was used on the influence parameters for high-speed braking performance. A new test method for brake dynamometer was developed in order to represent the circuit driving condition. The braking energy of a vehicle was calculated by using the vehicle speed data, while the new test method was derived by using the accumulated power during braking. The numerical regression model between the friction coefficient and influence parameters was derived by using the least squares method and its reliability was proven by using the ANOVA table.
정성필(Sung Pil Jung),조준희(Jun Hee Jo) 한국자동차공학회 2018 한국 자동차공학회논문집 Vol.26 No.6
This paper presents a new test method to calculate the tire rolling resistance when considering the vehicle’s cornering condition. The difference of force and torque methods in ISO 28580 is explained theoretically and experimentally. Vehicle test was performed in two locations, namely, Korea International Circuit(KIC) and real road. A mathematical model to represent the relationship between lateral acceleration, and slip and camber angles was derived from the test results at KIC. Lateral acceleration was measured from the real road test, while the slip and camber angle variation was estimated by using the derived mathematical model. The new rolling resistance coefficient of the tire when considering the cornering condition is calculated and compared with the one measured according to ISO 28580.
유한 요소법을 이용한 자동차용 디스크 브레이크의 열간 저더 해석
정성필(Sung Pil Jung),박태원(Tae Won Park),정원선(Won Sun Chung) 대한기계학회 2011 大韓機械學會論文集A Vol.35 No.4
차량 제동시 디스크와 패드사이의 미끄럼 접촉에 의해 발생하는 마찰열은 재질의 열 탄성 변형을 일으키고, 이는 접촉면의 압력 분포에 영향을 끼친다. 이러한 열탄성 불안정성 (Thermo-Elastic Instability, TEI)은 디스크의 고유 진동모드와 결합되어 열섬 현상 및 열간 저더 진동을 발생시킨다. 본 연구에서는 상용 유한 요소 해석 프로그램인 SAMCEF 를 이용하여 자동차용 통풍식 디스크에 대한 3 차원 열간 저더 해석을 수행하였다. Staggered approach 에 의거한 중간 처리기를 이용하여 구조-동역학 해석 결과와 열 전달 해석 결과를 교환하였다. 디스크 표면에 열섬이 발생하는 것을 확인하였고, 이를 디스크 고유 진동 모드와 비교함으로써 모드 형상과 열섬 분포의 관계를 분석하였다. Thermal energy generated because of the friction between the disc and pad is transferred to both sides and causes thermal expansion of the material, which affects the contact pressure distribution. This phenomenon, which is called thermoelastic instability (TEI), is affected by the natural mode of a disc. TEI results in the formation of a hot spot and causes hot judder vibrations. In this study, three-dimensional analysis of the hot judder of a ventilated disc for automotives was performed by using the commercial finite element analysis program, SAMCEF. The intermediate processor based on a staggered approach was used to exchange the result data of the mechanical and thermal model. The hot spot was formed on the surface of the disc, and the number of hot spots was compared with the natural mode of the disc.