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21.
Jinggao Li I. Kim S. Lee S. Han C. Lee S. Cheon W. Lee K. An G. Cho J. Hwang D. Mun 《Journal of Marine Science and Technology》2011,16(1):76-83
In the shipbuilding industry, different computer-aided design (CAD) systems are used for different design domains, structure, and outfitting. We need to exchange data among different CAD systems such as Tribon, AutoCAD, Intergraph or PDMS to complete the whole design and production process. There are two approaches to data exchange. One is direct translation; the other is indirect translation, which is based on a neutral format. If we use a neutral format, the data specification is open to the public and the design model can be used by other CAD systems, including next-generation CAD systems. In this paper, we propose an indirect method that uses ISO 10303 (STandard for the Exchange of Product model data) AP227 and ISO 15926 to define neutral formats. A separate ShapeDB is constructed to manage the geometry information, referenced to the catalogue data defined by ISO 15926. An experimental implementation for data exchange between Tribon and PDMS is described. 相似文献
22.
Idle stop and go (ISG) is a low cost but very effective technology to improve fuel efficiency and reduce engine emissions by preventing unnecessary engine idling. In this study, a new method is developed to improve the performance of conventional ISG by monitoring traffic conditions. To estimate frontal traffic conditions, an ultra-sonic ranging sensor is employed. Several fuzzy logic algorithms are developed to determine whether the engine idling is on or off. The algorithms are evaluated experimentally using various data gathered in real areas with traffic congestion. The evaluation results show that the method developed can reduce the chance of false application of ISG significantly while improving fuel efficiency up to 15%. 相似文献
23.
Junho Cho Tae-Kyung Kim Kyu-Hong Kim Kwanjung Yee 《International Journal of Automotive Technology》2017,18(6):959-971
To reduce the aerodynamic drag, the performance of the underbody aerodynamic drag reduction devices was evaluated based on the actual shape of a sedan-type vehicle. An undercover, under-fin, and side air dam were used as the underbody aerodynamic drag reduction devices. In addition, the effects of the interactions based on the combination of the aerodynamic drag reduction devices were investigated. A commercial sedan-type vehicle was selected as a reference model and its shape was modeled in detail. Aerodynamic drag was analyzed by computational fluid dynamics at a general driving speed on highway of 120 km/h. The undercover reduced the slipstream area through the attenuation of the longitudinal vortex pair by enhancing the up-wash of underflow, thereby reducing the aerodynamic drag by 8.4 %. The under-fin and side air dam showed no reduction in aerodynamic drag when they were solely attached to the actual complex shape of the underbody. Simple aggregation of the effects of aerodynamic drag reduction by the individual device did not provide the accurate performance of the combined aerodynamic drag reduction devices. An additional aerodynamic drag reduction of 2.1 % on average was obtained compared to the expected drag reduction, which was due to the synergy effect of the combination. 相似文献
24.
Joonsoo Han Junho Lee Youngtaig Oh Gyubaek Cho Hongsuk Kim 《International Journal of Automotive Technology》2017,18(6):951-957
Urea-SCR systems have been widely used in diesel vehicles according to the strengthened NOx (Nitrogen Oxides) emission standard. The NOx removal efficiencies of the latest well optimized urea-SCR system are above 90 % at moderate exhaust gas temperature of 250 ~ 450 °C. However, a large amount of NOx is emitted from diesel vehicles at cold start or urban driving conditions, when the exhaust gas temperature is not high enough for SCR catalyst activation. Although many researchs have been stuied to improve NOx conversion efficiency at these low temperature conditions, it is still one of important technical issues. In this study, the effect of UWS injection at low exhaust gas temperature conditions is studied. This study uses a 3.4 L diesel engine equipped with a commertial urea SCR system. As a result, it is found that about 5 % of NOx removal efficiency is improved in the NRTC test when UWS injection starts at the SCR inlet temperature of 150 °C compared to 200 °C. It is also found that urea deposits can be formed on the wall of exhaust pipe, when the local wall temperature is lower than temperature of urea decomposition. 相似文献
25.
This paper deals with the lane assignment problem in the Automated Highway Systems (AHS). The purpose of lane assignment strategies
is to increase throughput on multi-lane highways with many entry and exit points, based on the itineraries of vehicles using
the highway (point of entry, time of entry and exit point) and the effects of maneuvers. Using partitioned lane assignment
strategies, the lane assignment problem is formulated as an optimization problem to find the proper positions of partitions.
Then the optimal problem is solved using a Genetic Algorithm (GA). The proposed algorithm has been validated by comparing
its solution with that of an all-cases algorithm for a simple case. Moreover, a traffic simulator with a realistic car-following
model as well as lane change logic has been developed. The simulation results show the efficiency of the proposed genetic
algorithm, compared with random assignment algorithms. 相似文献
26.
Ki-Hyun Kim Sudhir Kumar Pandey Hang Thi Nguyen Soo-Yeoun Chung S.-J. Cho M.-Y. Kim J.-M. Oh Young Sunwoo 《Transportation Research Part D: Transport and Environment》2010,15(3):168-174
The concentrations of particulate matter, PM2.5, PM10, and TSP at an urban roadside and an urban background station are analyzed. Data collected over a 10 year period are analyzed. The concentrations of the particulates measured at the urban site are systematically larger than at the background station. The mean PM values at the former also exhibit a slight fall over the decade unlike those at the background station. Overall, the particulate matters at both locations are in an intermediate range of global level, e.g., approximately two times lower than those in other Asian regions but higher than in Europe. 相似文献
27.
Control of Wheel Slip Ratio Using Sliding Mode Controller with Pulse Width Modulation 总被引:3,自引:0,他引:3
Seongho Choi Dong-Woo Cho 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》1999,32(4):267-284
For the control of anti-lock brake system (ABS), a longitudinal four-wheel vehicle model with brake actuator is described and a sliding mode controller with pulse width modulation (PWM) method has been developed for passenger vehicles. In our research, we introduce actuator dynamics of solenoid-solenoid valve type in system equation and derive the sliding mode control input theoretically. We propose using PWM method to compensate for the discrete nature of actuator dynamics by duty control. The effectiveness of the proposed control algorithms was confirmed by vehicle test on an in-door test bench that was specially constructed for the purpose concerned. 相似文献
28.
Bu-Geun Paik Seong-Rak Cho Beom-Jin Park Dongkon Lee Byung-Dueg Bae Jong-Hwui Yun 《Journal of Marine Science and Technology》2009,14(1):115-126
In this study, basic experiments regarding the wireless sensor network were conducted on a 3,000-ton-class training ship as
the first step in applying the ubiquitous technology to a real ship. Various application fields of the technology in terms
of the provision of safety and convenience on a ship were identified through these experiments. To efficiently adopt the ubiquitous
technology for ship application, it is necessary to identify the state-of-the-art ubiquitous technology and to prepare countermeasures
against the harsh environment of a ship. The characteristics of the wireless sensor network were investigated on a test bed
ashore as well as on a real ship before full-scale ship application. In particular, experimental results concerning communication
depth, data transmission ratio, and battery consumption in a sensor node are described in detail. 相似文献
29.
Optimal liner fleet routeing strategies 总被引:1,自引:0,他引:1
30.
Fatigue life prediction based on the rainflow cycle counting method for the end beam of a freight car bogie 总被引:1,自引:0,他引:1
This paper presents a system for treating of the actual measured data for load histories. The approach consists of two steps:
stress analysis and fatigue damage prediction. Finite element analysis is conducted for the component in question to obtain
detailed stress-strain responses. A significant number of failures occurred in a brake end beam which led to economic losses
and disruption of service. The cracks appeared to be fatigue cracks caused by the dynamic load produced in the loaded bogie
frame. Strain gauge data were analyzed, and fatigue cycles were calculated from this data. Rainflow cycle counting was used
to estimate cumulative damage of the end beam under in-service loading conditions. The fatigue life calculated with the rainflow
cycle counting method, the P-S-N curve, and the modified Miner’s rule agreed well with actual fatigue life within an error
range of 2.7%~31%. 相似文献