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111.
We investigated the effects of the fuel injection timing — both for early and late injection — in conjunction with the throttle
opening ratio on the fuel-air mixing characteristics, engine power, combustion stability and emission characteristics of a
DI CNG spark engine and control system that had been modified and designed according to the author’s original idea. We verified
that the combustion characteristics were affected by the fuel injection timing and that the engine conditions were affected
by the throttle opening ratios and the rpm. The combustion characteristics were greatly improved for a complete open throttle
ratio with an early injection timing and for a partial throttle ratio with a late injection timing. The combustion duration
was governed by the duration of flame propagation in late injection timing scenarios and by the duration of early flame development
in cases of early injection timing. As the result, the combustion duration is shortened, the lean limit is improved, the air-fuel
mixing conditions are controlled, and the emissions are reduced through control of the fuel injection timing and vary according
to ratio of the throttle opening. 相似文献
112.
Until recently, passenger cars have primarily interested in pedestrian protection performance. Nowadays, however, it is important
for a sport-utility vehicle (SUV) to meet the bumper system standards for pedestrian safety. For a SUV bumper system, there
are some difficulties in attaining a high level of pedestrian performance for the lower legform. An SUV has a high bumper
position from the ground level, and the bumper approach angle must also be secured, which has an effect on car insurance fees.
Due to these reasons, it is difficult to meet the pedestrian performance of the lower legform for an SUV. In this paper, a
comparative study was performed on various SUV bumper systems, and a concept model for a SUV bumper system was developed,
which is expected to meet the pedestrian performance by using the Pugh method. The design control factors were defined to
affect the bumper pedestrian performance through the experiences of tests and analyses. For the noise factor to affect the
pedestrian performance, the deviation of the impactor position was selected at the moment of impact. The design control factors
were optimized by using the Taguchi optimization technique. For the Taguchi method, an L18 orthogonal array table of design
control factors was used in the optimization process. Particularly, for the optimization of the bumper corner region, an optimization
analysis was performed three times to meet pedestrian performance. Based on the results of the Taguchi optimization method,
the sensitivity of the bumper design parameters was studied, and a new SUV bumper system is proposed that satisfies the pedestrian
performance of the lower legform. The optimized bumper system should obtain a full Euro-NCAP score of 6 points for the bumper
test. The pedestrian performance of the optimized bumper system is validated by using a CAE (Computer Aided Engineering) analysis,
which has been proven to be in accurate. A comparison between the test and analysis results is shown for the validation of
accuracy. By using the optimized bumper system, the tests and development costs of a bumper can be reduced. 相似文献
113.
Sung Jun Ha Ung Chun Jong Yun Park Moon Sang Kim 《International Journal of Automotive Technology》2017,18(5):779-784
High pressure acting on the vehicle’s body plays an important role in deciding the aerodynamic drag. An idea has been suggested to enhance the aerodynamic performance for small passenger car by relieving the high pressure in the engine room. The high pressure inside the engine room can be released to the outside of the vehicle through a hole perforated on the wheel house liner. About 1 % of the drag coefficient can be improved with the 1.88 % of the radiator air mass flow rate increment by installing the top hole with slots on the wheel house liner. Flow simulations are performed at the driving velocity of 110 km/h with the moving wall condition of the same velocity. The tire is rotating to catch more precise flow physics around a tire and wheelhouse liner. 相似文献
114.
Myeong Jae Han Chul Hyung Lee Tae Won Park Jung Min Park Sung Min Son 《International Journal of Automotive Technology》2017,18(6):1027-1035
In vehicle braking systems, the non-uniform contact pressure distribution on the brake pad is a major cause of uneven wear. The experimental approach of the wear phenomenon is the time consuming and costly. For this reason, a threedimensional finite element (FE) model of a brake system is presented for numerical simulation in this paper. A coupled thermo-mechanical analysis is carried out to confirm the non-uniform contact pressure distribution. A correlation between the non-uniform contact pressure and uneven wear is confirmed by measuring the amount of wear in the brake pad. The shape optimization of the brake pad is performed to reduce the uneven wear. In addition, the simulation results, such as natural frequency and temperature, are compared to experimental results. 相似文献
115.
Young Ho Kim Kyung-Il Chang Jong Jin Park Seon Ki Park Sang-Hyun Lee Young-Gyu Kim Kyung Tae Jung Kuh Kim 《Journal of Marine Systems》2009,78(2):249
Reanalyzed products from a MOM3-based East Sea Regional Ocean Model with a 3-dimentional variational data assimilation module (DA-ESROM), have been compared with the observed hydrographic and current datasets in the Ulleung Basin (UB) of the East/Japan Sea (EJS). Satellite-borne sea surface temperature and sea surface height data, and in-situ temperature profiles have been assimilated into the DA-ESROM. The performance of the DA-ESROM appears to be efficient enough to be used in an operational ocean forecast system.Comparing with the results from Mitchell et al. [Mitchell, D. A., Watts, D. R., Wimbush, M., Teague, W.J., Tracey, K. L., Book, J. W., Chang, K.-I., Suk, M.-S., Yoon, J.-H., 2005a. Upper circulation patterns in the Ulleung Basin. Deep-Sea Res. II, 52, 1617-1638.], the DA-ESROM fairly well simulates the high variability of the Ulleung Warm Eddy and Dok Cold Eddy as well as the branching of the Tsushima Warm Current in the UB. The overall root-mean-square error between 100 m temperature field reproduced by the DA-ESROM and the observed 100-dbar temperature field is 2.1 °C, and the spatially averaged grid-to-grid correlation between the two temperature fields is high with a mean value of 0.79 for the inter-comparison period.The DA-ESROM reproduces the development of strong southward North Korean Cold Current (NKCC) in summer consistent with the observational results, which is thought to be an improvement of the previous numerical models in the EJS. The reanalyzed products show that the NKCC is about 35 km wide, and flows southward along the Korean coast from spring to summer with maximum monthly mean volume transport of about 0.8 Sv in August–September. 相似文献
116.
许筠被朝鲜学者称为朝鲜的李贽.李贽是阳明左派,许筠是儒学者徐敬德、李幌的左派,两人的思想和行为十分相似.当代韩国学术界在分析许筠的思想体系时,常将他与李贽相联系.许筠曾数次接待明廷使臣,又几度以使臣的身份出使明朝,期间购买许多书籍带回半岛.笔者在本文中对许筠何时、如何购得李贽的著作及其反应,进行集中考察. 相似文献
117.
Safety mechanism is required for an automotive battery pack to prevent thermal failure which could lead to catastrophic events. Passively cooled battery packs can prevent thermal failure by conducting adaptive control of battery power without any external cooling device. The key to this power control is how to secure battery safety while minimizing energy loss. This paper proposes a novel, adaptive power control strategy for automotive passive-cooling battery packs. Four different cases with electrochemical battery model are simulated and compared to each other according to a city driving profile. Driving simulation result confirmed that the present power control algorithm is an effective solution for preventing thermal failure along with improving energy efficiency of automotive battery packs. 相似文献
118.
Due to rapid progress in LED (Light Emitting Diode) technology, LEDs have become increasingly prevalent in applications to
automotive lighting. This paper studies recent trends of LED headlamps along with various experiments regarding photometric
characteristics, glare, and visibility. Experimental results are compared to those of halogen and HID (high intensity discharge)
headlamps. LED headlamps are found to be still inferior to conventional headlamps with respect to glare. However, many properties
of LED headlamps (luminous intensity, beam width, energy efficiency, and design) are competitive with halogen and HID headlamps.
The findings in this investigation will henceforth be reported to the Korean Motor Vehicle Safety Standard (KMVSS). 相似文献
119.
Y. -K. Park Y. -J. Moon Y. -S. Cho K. -J. Kum 《International Journal of Automotive Technology》2013,14(2):275-281
This paper demonstrates the results of field tests for assessing a cooperative intersection signal violation warning system (CISVWS), which consists of (a) hardware, including an in-vehicle warning device, roadside antenna, and traffic signal controller, and (b) software to operate and test the cooperative system through vehicle to infrastructure (V2I) communication systems. Field tests were performed under real traffic situations in order to test the system in terms of the initiation time of the signal violation warning from the signal controller, the activation and duration of on board equipment (OBE), and the warning delay based on the relationships between distance variables, including the safe stopping distance, and the location of road side equipment (RSE). Findings from the field test at the real-world signalized intersection sites indicated that the system would be capable of reducing red light violations and intersection collisions through use of the in-vehicle warning device at signalized intersections. 相似文献
120.
Disruptions in automated manufacturing systems for machining automotive parts caused by system changes and disturbances reduce the productivity, and increase the downtime as well as the cost of products. To cope with these challenges, the paper presents a biology inspired manufacturing system (Bio-MS). The model of Bio-MS is inherited from the organization of the living systems in biology and nature such as ant colony, school of fish, bee’s foraging behaviors, and so on. In which, the resources of the manufacturing system are considered as biological organisms, which are autonomous entities so that the manufacturing system has the advanced characteristics inspired from biology such as self-adaptation, self-diagnosis, and self-healing. To realize the Bio-MS, the cognitive agent and swarm intelligence were proposed. The disturbances happening when machining the transmission cases at an automotive company in Korea were analyzed to classify them and to find out the corresponding management methods. Currently, the system utilization was too low due to the manual recovery, only 70–76 percent of total production time is used for manufacturing and the rest of the time is wasted in different disturbances. The Bio-MS with autonomous behaviors adapts efficiently to the changes of the manufacturing environment. It enables to increase the system utilization more than 80 percent. 相似文献