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381.
Sung-Wook Kim Jae-In Ko Ilsoo Cho Hyungjin Kim Joo-Hyung Lee Dongil Dan
Cho 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》2002,37(5):377-394
Conventionally a phase-shift detection method (PSDM) and a frequency-shift detection method (FSDM) have been used in loop detectors. The PSDM has a fast response time and is very effective in detecting vehicles traveling at normal speeds. However, it is well known that the detection results are erroneous for vehicles traveling at low speeds in heavy traffic conditions. On the other hand, the FSDM greatly improves the detector performance for heavy traffic conditions. However, this method is not effective in fast and normal traffic conditions. Thus, in order to collect accurate traffic data for all traffic conditions, this paper proposes combining two methods using the digital OR logic. In the developed circuit, a phase-locked loop (PLL) circuit is used for measuring the phase change. This paper also develops a new loop detector instrumentation method using the so-called M circuit for detecting frequency change. The developed method has been tested for various traffic conditions. Experimental results show that the new combined M and PLL detection method greatly improves the accuracy in all traffic conditions, reducing the error rate in measuring traffic flow by more than 83%, when compared to the PSDM. 相似文献
382.
The current control system of a fully submerged hydrofoil craft has manual input of fore-foil depth and control mode selection to improve the performance of the control system. However, the manual input needs skillful human operation and observation of waves the encountered to work well over a wide range of waves. In order to use information about the waves encountered in the control system, we considered the estimation of wave elevation and wave disturbance which was caused by the orbital motion of the waves in irregular waves. First, we investigated the wave disturbance by a fully submerged hydrofoil craft, in a state-space model of wave disturbance, and in hydrofoil craft motion, etc. We than considered estimations of the wave elevation and wave disturbance using a shaping filter, a Kalman filter, an autoregressive (AR) model, etc. Finally, we confirmed through simulations that the estimation results and estimation error of wave elevation and wave disturbance were valid. 相似文献
383.
Taeksu Jung Yunhwa Hong Sungsu Park Cheongmin Kim Younghoon Hong Chongdu Cho 《International Journal of Automotive Technology》2018,19(2):281-289
Automotive brake noise has become a stubborn problem as automotive cars achieve higher driving torques, since that the increased torque induces the generation of severe noise dissipation during brake operation. Moreover, the global brake tuning market for achieving higher performance of the vehicle has expanded recently. The need to control the noise grows more in this connection. The tuning brake kits have employed cross-drilled and slotted machining pattern on the surface of the rotor. These designs have advantages to improve air ventilation, temperature control, and surface cleaning of brake pad. However, the effects of modal frequency by patterned rotor surfaces are rarely discussed, even if it is highly related with brake squeal phenomenon. Therefore, this study deals with the relationship between patterned surfaces and brake squeal through the numerical methods. The commercial software of a finite element analysis is employed for calculation by varying geometric design factors of each rotor pattern. As a result, the cross-drilled machining patterns are concluded to be an influential factor for in-plane mode frequency while the slotted patterns have more leverage for out-of-plane mode frequency. 相似文献
384.
J. Kim 《International Journal of Automotive Technology》2008,9(6):687-693
In this article, the analysis methods for vehicle handling performance are studied. Using simple models, dynamic characteristic
parameters such as yaw, natural frequency, and the damping coefficient of a vehicle can be theoretically formulated. Here,
the vehicle is simplified by a bicycle (single-track) model, and the tire is modeled by an equivalent cornering stiffness
and first order lag. From the experimental road data, the tire model parameters (equivalent cornering stiffness and time lag
constant) are extracted. These parameters are then inserted into the theoretically formulated equations of dynamic characteristic
parameters. For the purpose of validating the efficiency of the suggested methods, experimental road tests (where the cars
have different handling performances) are performed. The results show that vehicle handling performance can be sufficiently
represented by the suggested dynamic characteristic parameters. So, it is concluded that the proposed method has practical
use for the development of new cars or for the comparison of similar cars since the evaluations of the vehicle handling performance
can be efficiently determined by the suggested dynamic characteristic parameters. 相似文献
385.
In the following paper, a numerical study of the atomization, vaporization and wall impingement processes of hollow-cone fuel
spray from high-pressure swirl injectors under various ambient temperature conditions was carried out. Also, the availability
of applied models and the effect of ambient temperature on spray characteristics is discussed. The Linearized Instability
Sheet Atomization (LISA) model combined with the Aerodynamically Progressed Taylor Analogy Breakup (APTAB) model, the improved
Abramzon model and the Gosman model are used to calculate the atomization, vaporization and wall impingement processes of
hollow-cone fuel spray, respectively. Spray models are implemented with the modified KIVA code. The calculation results of
the spray characteristics under two ambient temperatures, including spray tip penetration, spray structure and radial distance
after spray-wall impingement are compared to the experimental results obtained by the Laser Induced Exciplex Fluorescence
(LIEF) technique. The droplet size distribution, ambient gas velocity field, vapor phase distribution and fuel film mass generated
by spray-wall impingement, measurements which are generally difficult to obtain by experimental methods, are also calculated
and discussed. Quantitative discussions on the effect of the ambient temperature on the spray development process are conducted.
It is shown that the applied models are applicable even in the high ambient temperature condition. 相似文献
386.
S. -H. Kim E. -J. Han S. -W. Kang S. -S. Cho 《International Journal of Automotive Technology》2008,9(2):233-247
This paper investigates the brake corner system to reduce brake torque variation in the brake judder problem. A numerical
model for determining brake torque variation was constructed using the multi-body dynamics model. Using this model, the brake
torque variation for a given disc thickness variation was obtained in the time domain. The multi-body dynamics model was verified
by a dynamometer test via the comparison of brake torque variation and load distribution patterns of the pad. To reduce the
simulation time and cost required to determine factors that influence the reduction in brake torque variation, a simple mathematical
model was constructed and used to determine both the brake torque variation and influential factors. The multi-body dynamics
model and dynamometer test were modified on the basis of the results of the simple mathematical model and deformed shape of
the multi-body dynamics model. These influential factors were verified to reduce the brake torque variation. 相似文献
387.
C. Hein S. Hong J. Suh H. Hoffmann N. Kim 《International Journal of Automotive Technology》2008,9(2):211-216
It is essential to develop efficient and cost-effective production methods to achieve or maintain international competitiveness.
An innovative production method, such as rotary blanking, enables manufacturers to both reduce expenses and economize production
time. However, there are not enough numerical analyses for this process. In this paper, numerical simulations of rotary blanking
were performed. After comparing the cutting planes generated by conventional and rotary blanking experimental tests, the cutting
areas of two punch geometries were analyzed. The influence of punch geometry on part quality was then investigated through
simulations. The procedure for die stress analysis was established and stress distributions of the worksheet and the tools
were analyzed. 相似文献
388.
When soot particles are loaded in a diesel particulate filter, it causes increase in back pressure of the exhaust system.
To minimize this pressure drop due to DPF, the filter needs to be regenerated after a certain amount of soot has been accumulated.
It is crucial to estimate the correct amount of soot that has been accumulated by measuring the differential pressure. It
is also important to understand changes in pressure drop due to flow rate variations of the exhaust gas, since the pressure
drop would be influenced by the exhaust flow rate as well as the amount of soot. Furthermore, the heat transfer characteristics
of the catalyzed diesel particulate filter (CDPF) are another major issue, as the filter is occasionally exposed to high temperature
gas. This study presents the characteristics of pressure drop according to the variation of soot loading and the mass flow
rate in CDPF. In addition, heat transfer characteristics in the filter was investigated when a high temperature gas flows
into the CDPF. Tests were performed in several CDPF samples having varying amounts of catalyst coating. Experimental results
indicate that rig-based experiments are useful in understanding the characteristics of pressure drop in the CDPF. In the cake
filtration region, a pressure drop has a proportional relationship according to soot loading and mass flow rate. It was found
that an increased catalyst coating may lead to enhanced convective heat transfer. 相似文献
389.
Hyung Rim Choi Hyun Soo Kim Byung Joo Park Nam-Kyu Park Sang Wan Lee 《Maritime Policy and Management》2013,40(3):197-210
The major characteristics of ERP (Enterprise Resource Planning) are an enterprise-wide system that covers all the business functions and information resources, integrated database, built-in best industry practice, packaged software and open architecture. ERP enables reduction of system development time, flexibility, standardization of workflow and effective business planning capability. ERP is mainly for the manufacturing industry. However, the principles of ERP can also be applied to container terminal operating systems. This paper presents an ERP system approach for a container terminal. It has clustered the workflow of a container terminal and analysed the business process to generate the best workflows. The integrated database is designed to eliminate redundancy and keep integration. The core of ERP for container terminal is the planning facility such as berth planning and yard planning. The planning capability is very tightly coupled with data flow from client entities such as shipping companies. The ERP can handle the existing problems of container terminal operation that are mainly caused by lack of integration of a whole information resource in a container terminal, ad-hoc and poor planning capability, disconnected and incorrect data from client companies. The ERP approach can not only resolve the problems of container terminals but also promote adoption of information systems for container terminals in the world that have not yet implemented terminal operating systems. 相似文献
390.
Jouni Lappalainen Anne Vepsäläinen Kim Salmi Ulla Tapaninen 《WMU Journal of Maritime Affairs》2011,10(2):167-181
The purpose of the International Safety Management Code (the ISM Code) is to promote safety culture in the maritime industry.
Learning the lessons from incidents should help to improve safety performance since incidents and accidents can share the
same root causes. The aim of this paper is to take a closer look at incident reporting in the Finnish shipping industry, to
study the reasons for poor incident reporting and to suggest improvements to increase reporting. The paper consists of a literature
study, which focuses on previous studies concerning incident reporting, and an interview study, which focuses on Finnish shipping
companies and their personnel. The interview study confirmed that incident reporting does not function properly within the
Finnish maritime industry. The maritime personnel have an occupational culture which is incompatible with the rule-based safety
management approach provided by the ISM Code. The willingness to report incidents could be increased if all seafarers were
involved in the reporting process and the preparation of corrective actions. In addition, the reporting procedures should
be streamlined and developed to a more user-friendly direction. 相似文献