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공기 유압식 브레이크 라인 파손 사례 및 파손 분석 연구
박정만,박종진,Park, Jeongman,Park, Jongjin 한국자동차안전학회 2020 자동차안전학회지 Vol.12 No.2
In this case study, the brake line failure of air over hydraulic(AOH) brake system is described. AOH brake system is applied to commercial vehicles between 5 to 8 tons. It consists of a hydraulic system using compressed air and operates the air master to form hydraulic pressure to transfer braking power to the wheels. When the brake lines of the system applied to vehicles with high load capacity are damaged, the braking force of one shaft is lost, and the braking distance increases rapidly, leading to a big accident. Failure of the brake line occurs due to various causes such as road surface fragmentation, corrosion of the line, and aged deterioration of air brake hose. The braking force could be decreased even when a very small break in the form of a pin-hole occurs. However, it is difficult to find a part where the thickness of the line is thin due to stone pecking or corrosion generated in the pin-hole formed on the brake line located under the lower part of the vehicle by the sensory evaluation or the conventional braking force test. Accordingly, it is necessary to analyze the condition and cause of the failure of the brake line more precisely when the accident investigation of the heavy vehicles, and also to examine the necessity of the advanced test for the aged brake line.
2 stage CVT 가속성능 개선 변속 제어 알고리즘 개발
박정만(Jeongman Park),지건(Jian Ji),권오은(Oheun Kwon),채민재(Minjae Chai),심장선(Jangsun Sim),임광혁(Kwanghyuk Lim),조서연(Seoyeon Cho),김현수(Hyunsoo Kim) 한국자동차공학회 2012 한국자동차공학회 학술대회 및 전시회 Vol.2012 No.11
In this study, a 2 stage CVT shift control algorithm is proposed for kickdown shift to improve acceleration performance. The proposed shift control algorithm controls a desired secondary pressure to increase a variator shift speed and a release clutch pressure to shift a planetary gear smoothly. In order to evaluate acceleration performance of the control algorithm, a 2 stage CVT vehicle simulator is developed based on MATLAB/Simulink and SimDriveline. It is found from the simulation results that an acceleration performance is improved in terms of an increase of variator shift speed.
박정만(Jeongman Park),김강현(Kanghyun Kim),신종호(Jongho Shin) 한국지반환경공학회 2018 한국지반환경공학회논문집 Vol.19 No.3
파이핑은 가장 대표적인 제방의 붕괴 유형으로 불투수성 수리구조물과 지반 경계면에서 Backward Erosion Piping인 루핑(Roofing)이 흔하게 발생한다. 루핑에 대한 검토는 주로 경험적 방법인 크립비를 이용하지만 이는 지반-구조물 경계면의 특성을 고려하지 않는 문제가 있다. 본 연구에서는 지반-구조물 경계면 특성이 루핑에 미치는 영향을 평가하기 위해 모형시험과 수치해석을 이용하여 파이핑 위험도를 고찰하였다. 모형시험에서 경계면 조도가 커질수록 파이핑 포텐셜이 감소함을 확인하였으며, 이를 수치해석에 적용하였다. 기존의 일반적인 수치해석방법은 수위차만을 고려하므로 경계면에서의 입자거동을 적절히 모사할 수 없다. 논문에서는 침투해석을 통해 침투력을 구하고, 입자해석기법을 이용해 파이핑의 입자거동을 모사한 침투-입자거동 연계해석을 수행하여 지반-구조물 경계면 조건에 따른 루핑 포텐셜을 조사하였다. 해석결과 경계면의 조도가 감소할수록 루핑 발생 확률이 증가함을 확인하였다. Piping is one of the most frequently occurring collapse type of a levee, and is often caused by roofing (backward erosion piping) at the ground-structure interface. Roofing is generally evaluated using creep ratio. However, creep ratio does not take into account the characteristics of the ground-structure interface. In this study, the roofing risk was investigated by using model test and numerical analysis considering the ground-structure interface characteristics. In the model test, it was confirmed that the piping potential decreased as the interface roughness increased, and this was applied to the numerical analysis. Existing numerical methods can not adequately simulate the particle behavior at the ground-structure interface because only the water level difference is considered. In this paper, particle behavior at the interface was investigated by performing seepage analysis and then, carrying out particle analysis technique simulating the boundary condition of the ground-structure interface. Analysis results have shown that the roofing resistance decreases as the ground-structure interface roughness decreases.
박종진,박정만,이연섭,Park, Jongjin,Park, Jeongman,Lee, Yeonsub 한국자동차안전학회 2020 자동차안전학회지 Vol.12 No.3
Usage of EDR(Event Data Recorder) report for traffic accident analysis is currently increasing due to government regulation of EDR data release. Nevertheless, a lot of investigators simply adopt by comparing the number of ignition cycles(crash) at event to the number of ignition cycles(download) without an exact judgment whether event data occurred by this accident or not. In the EDR report, besides ignition cycles, there are many factors such as event record type, algorithm active(rear/rollover/side/frontal), time between events, event severity status(rollover/rear/right side/reft side/frontal), belt switch circuit status, driver/passenger pretensioner/air-bag deployment, PDOF(Principal Direction of Force) by ΔV to be able to decide whether or not to adopt. also the event data is considered enough to vehicle damaged state, accident situation at the scene of the accident. and there is described in "all data should be examined in conjunction with other available physical evidence from the vehicle and scene" in the CDR(Crash Data Retrieval) report. Therefore many investigators have to decide whether or not to adopt after they consider sufficiently to above factors when they are the traffic accident analysis and investigate the causes of a accident on the adopted event data. In this paper, we report to traffic accident investigators notable points and analysis methods on the basis of thousands of cases and the results of one's own experiment in NFS(National Forensic Service).
박종진,최영수,박정만,Park, Jongjin,Choi, Youngsoo,Park, Jeongman 한국자동차안전학회 2021 자동차안전학회지 Vol.13 No.3
Recently a traffic accident of heavy duty vehicles under the mandatory installation of ADAS (Advanced Driver Assistance System) is often reported in the media. Heavy duty vehicle accidents are normally occurring a high number of passenger's injury. According to report of Insurance Institute for Highway Safety, FCW (Forward Collision Warning) and AEB (Automatic Emergency Braking) were associated with a statistically significant 12% reduction in the rate of police-reportable crashes per vehicle miles traveled, and a significant 41% reduction in the rear-end crash rate of large trucks. Also many countries around the world, including Korea, are studying the effects of ADAS installation on accident reduction. Traffic accident statistics of passenger vehicle for business purpose in TMACS (Traffic safety information Management Complex System in Korea) tends to remarkably reduce the number of deaths due to the accident (2017(211), 2018(170), 2019(139)), but the number of traffic accidents (2017(8,939), 2018(9,181), 2019(10,095)) increases. In this paper, it is introduced a traffic accident case that could lead to high injury traffic accidents by being equipped with AEB in a bus. AEB reduces accidents and damage in general but malfunction of AEB could occur severe accident. Therefore, proper education is required to use AEB system, simply instead of focusing on developing and installing AEB to prevent traffic accidents. Traffic accident of AEB equipped vehicle may arise a new dispute between a driver's fault and vehicle defect. It is highly recommended to regulate an advanced event data recorder system.
2 stage 금속 벨트 CVT의 변속 제어 알고리즘 개발 및 성능 해석
전영호(Youngho Jun),지건(Jian Ji),박정만(Jeongman Park),김병준(Byungjun Kim),심장선(Jangsun Sim),조서연(Seoyeon Cho),김현수(Hyunsoo Kim) 한국자동차공학회 2011 한국자동차공학회 학술대회 및 전시회 Vol.2011 No.11
A shift control algorithm was proposed for a 2 stage CVT by considering the shift speed of the CVT and the planetary gear. In order to evaluate shift quality for the suggested shift control algorithm, a 2 stage CVT performance simulator was developed based on the CVT powertrain. From the simulation results, it was found that variation of the total gear ratio can be decreased in transient period. Consequently, torque variation of driveshaft was decreased, which provides improved shift quality. In addition, when the target gear ratio changed during the shift, the total gear ratio followed the target gear ratio by shift control algorithm.