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박정률(Jeong Lyul Park),이상범(Sang Beom Lee),임홍재(Hong Jac Yim) 한국자동차공학회 2001 한국 자동차공학회논문집 Vol.9 No.3
Joint stiffnesses can affect the vibrational characteristics of car body structures and, therefore, should be included in vehicle system models. In this paper, a numerical approximation of joint stiffness is presented for considering joint flexibility of thin walled beam jointed structures. Using the proposed method, it is possible to optimize joint structures considering the change of section shapes in vehicle structures. The numerical approximation of joint stiffnesses is derived using the RSM(Response Surface Method) in terms of beam section properties. The study shows that joint stiffnesses can be effectively determined in designing vehicle structure.<br/>
[구조강도부문] 차체 구조물의 최적설계를 위한 결합부 강성의 근사적 수식화에 관한 연구
박정률(Jeong Lyul Park),이상범(Sang Beom Lee),임홍재(Hong Jae Yim) 한국자동차공학회 2000 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
Joint stiffnesses can effect the vibrational characteristics of car body structures and, therefore, should be included in vehicle system models. In this paper, a numerical formulation of joint stiffness is presented for considering joint flexibility of thin walled beam jointed structures. Using the proposed method, it is possible to optimize joint structures considering the change of section shapes in vehicle structures. The numerical approximation of joint stiff nesses is derived using the RSM(Response Surface Method) in terms of beam section propcr1ies. The study shows that joint stiffnesses can be effectively determined in designing vehicle structure.
일과성 뇌허혈에서 혈당의 변화가 국소 뇌조직의 신경전달물질 농도변화에 미치는 영향에 관한 실험적 연구
김봉룡,박정률,박윤관,정흥섭,이기찬,이훈갑 대한신경외과학회 1994 Journal of Korean neurosurgical society Vol.23 No.8
Hyper glycemia during either global or regional ischemia is widely known to be detrimental, and ischemia induced release of diverse neurotransmitters and the ensuing activation of specific postsynaptic receptors have been suggested to play a important role in the development of ischemic selective vulunerability. This study was undertaken to investigate the influence of blood glucose change on tissue concentration of some catecholamies ; dopamine, norepinephrine, serotonin, of the transient ischemic rat's brain, estimated by high performance liquid chromatography(HPLC) assay system, following trnasient bilateral forebrain ischemia in the rat's model subjected to 20 minutes of normothermic ischemia by two vessels occulusion plus profound hypotension. Norepinephrine, dopamine and serotonin levels were measured in the frontal cortex, hippocampus and striatum respectively by HPLC. The concentrations of catecholamines were significantly decreased in all sampled ares in experimental groups compared with the control group(p<0.05), respectively(average decrease rate : norepinephrine 71%, dopamine 89%, serotonin 80% in frontal cortex ; norepinephrine 33%, dopamine 35%, and serotonin 78% in striatum). Dopamine was relatively decreased in concentration in frontal cortex and hippocampus, and serotonin was relatively decreased in striatum. But no statistic significancy(p>0.05) of catecholamines level between each experimental group(hyper-, hypo- and normoglycemic group) according to the change of blood sugar. The results suggested that blood glucose level did not influence the tissue concentration of dopamine, norepinephrine and serotonin in frontal cortex, hippocampus and striatum of transient ischemic rat's brain.
디젤 기관의 연소와 배출물에 관한 연구 -경유-물물의 유화연료 사용시-
조진호,김형섭,박정률 대한기계학회 1992 대한기계학회논문집 Vol.16 No.1
본 연구에서는 와류실식 디젤 기관에 경유-물의 유화연료 사용시 시관의 회전 속도(1500rpm)가 일정인 경우 물의 첨가량(체적비, 0~20%)과 기관의 부하(BMEP,2.1~ 7.5kg/$\textrm{cm}^2$)변화에 따른 연소실내 압력, 압력상승률 및 열발생률, 착화지연 기간, 연료 소비율 등의 연소특성과 CO, HC, NOx 및 매연의 배출능도 등 유해 배출 가스에 미치는 영향에 관하여 실험적으로 구한 것이다. By means of the compatibility according to solving environmental pollution and energy problem due to the emissions of NOx and smoke from diesel engine this paper experimentally inspected the effect of using emulsified fuel, gas oil-water, for combustion characteristic, that is combustion pressure, pressure rise rate, heat generating rate, the period of ignition delay and specific fuel consumption, and CO, HC, NOx concentration and smoke density. When using emulsified fuel, as a water addition rate was increased, combustion pressure, pressure rise rate and heat generating rate was increased, the period of ignition delay was lengthening, the specific fuel consumption was some what increased in contrast to diesel fuel in low load, but deceased in high load region. And NOx concentration was decreased, CO concentration was increased in low load, but decreased in high load region, HC concentration was increased in contrast to diesel fuel in all region.
내연기관용 엔진제어 최적화 개발을 위한 고도 별 차량 운전환경을 재현하는 시뮬레이터에 관한 연구
정찬(Chan Jeong),박정률(Jungryul Park) 한국자동차공학회 2012 한국자동차공학회 부문종합 학술대회 Vol.2012 No.5
The oxygen partial pressure for internal combustion engines is a major factor that affects engine performance. At high altitudes, engine performance is degraded because the reduction of oxygen partial pressure makes less air flow into the combustion chamber. This is a general characteristic of high-altitude driving conditions. The ambient pressure is a required input for engine management system(EMS). Functions such as fuel injection, exhaust gas recirculation (EGR) and canister purge need to know the ambient pressure to perform the necessary control functions. For the purpose, some of local testing at the real high altitude inevitably has to perform to obtain reliable EMS calibration data, although it requires much time and cost. Instead of the local testing, special facility (chassis dynamometer as Super Wind Tunnel) which can control the ambient pressure may be used but, there is a limit to simulate all possible actual road driving conditions. Therefore, the present research was designed for a vehicle simulator which can reproduce vehicle driving conditions by altitude at a sea level or available altitudes in Korea, to enable the optimization of engine control parameters. This design was examined as an effective countermeasure enough to obtain minimum EMS calibration data required at each altitude, save local testing cost and shorten vehicle development lead time.
Birfield Joint(BJ)의 내부력에 대한 다물체 동역학 해석
유창범(Changbeom Yu),박정률(Jeonglyul Park),오병기(Byungki Oh) 한국자동차공학회 2010 한국자동차공학회 학술대회 및 전시회 Vol.2010 No.11
The purpose of this paper is to analyze internal forces of Birfield Joint(BJ) using multibody dynamics. Calculating internal forces is critical to optimize design of BJ. The dynamic model of BJ is defined by considering relative motions between internal parts which are inner race, ball, cage and outer race. The contact forces between internal parts are modeled by Hertzian contact theory and frictions are modeled by fluid friction using MSC.ADAMS user-written subroutines. Internal forces of BJ with articulation angle variation are studied and verified with experimental results.