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11.
Jae Woo Chung Nam Ho Kim Deok Jin Kim Seong Sik Jang 《International Journal of Automotive Technology》2018,19(2):209-220
Recently, to improve vehicle fuel economy, as well as the performance of internal combustion engines, optimized system matching between a vehicle’s drivetrain and engine has become a very important technical issue. For this reason, the need for simulation research on engine and vehicle performance improvement has increased. But in general, since both engine simulation and vehicle simulation require initial engine calibration map input, a simple engine calibration method is required for the efficient configuration of various virtual engine calibration map setups. On this background, in this study, an example of waste gate turbocharger (WGT) cooled — exhaust gas recirculation (EGR) Diesel engine calibration using a test-based mean value engine model is presented as a suitable engine calibration map setting method. Also, the feasibility of an engine calibration model is confirmed through various engine tests. Using the simple model presented here, it is possible for diverse engine operating conditions and engine performance maps to be acquired. 相似文献
12.
Cheol Woong Park Chang Gi Kim Young Choi Sun Youp Lee Sung Won Lee Ui Hyung Yi Jang Hee Lee Tae Min Kim Duk Sang Kim 《International Journal of Automotive Technology》2017,18(6):1061-1066
Natural gas fuel, as an alternative energy source of transportation, has been used widely since it has an advantage of low emission levels. However, new technologies are required in order to meet the reinforced emission regulations. For this purpose, research into the development of hydrogen-compressed natural gas (HCNG) blend engine was carried out to evaluate its feasibility and emission characteristics. The Engine Research Department at the Korea Institute of Machinery and Materials carried out a large number of tests based on various parameter changes that could affect the performance and emission of HCNG engine in different operating conditions. An earlier stage of the research project focused on the lean combustion of a HCNG engine for heavy duty vehicles to meet the EURO-VI standards. An 11-L/6-cylinder CNG engine was used for the test. The effects of the excess air ratio change were assessed based on various content ratios of hydrogen in the natural gas fuel. In the later part of the HCNG research, a stoichiometric mixture operation was suggested to meet reinforced emission regulation without requiring a De-NOx system. Additionally, an exhaust gas recirculation (EGR) system was introduced for the purpose of improving thermal efficiency and durability. The optimal operating conditions were selected to achieve the best thermal efficiency to meet the required emission levels. In this paper, we demonstrate that a HCNG engine can achieve a significant decrease in NOx emissions, as compared to that of a CNG engine, while meeting the requirements of the EURO-VI standards during a transient mode cycle test. EGR can suppress the weakness of stoichiometric mixture combustion strategy, such as the deterioration of the durability and thermal efficiency, while the emission level can be lowered with the use of a three-way catalyst. The possibility of further reduction of emissions and CO2 with EGR was evaluated to access practical application of a HCNG engine in the field. From that evaluation, the HCNG engine with stoichiometric mixture operation for heavy duty vehicles was developed. The emission levels of HCNG engine were 50 % lower when compared to the EURO-VI standards with a greater than 10 % decrease in CO2 compared to that of a natural gas engine. 相似文献
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Beom-Seon Jang Benedikte Harstad Kallåk Chang-Hyun Lee Dae-Eun Ko Yong-Suk Suh Young-Soon Yang 《Journal of Marine Science and Technology》2010,15(1):23-33
As the concept of concurrent engineering has emerged along with support for optimization techniques, lots of endeavors have
been made to apply optimization techniques to real design problems for holistic decision-making. Even if the range of design
problems to which optimization is applicable has been extended, most ship designs use an iterative and manual approach due
to the difficulties of seamless integration of all related design activities. This paper proposes a process-centric management
framework for the preliminary ship design process depending on these approaches. Requirements for the framework are generated
based on the features of the ship design process first. The proposed framework consists of both process scheduling and process
management parts. Each of these modules is divided into submodules, and the modules and their interactions are elaborated
to reflect actual design practice. The designed framework is embodied within a workflow system and its usefulness examined
through a pilot project. 相似文献
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At the initial design stage, for rapid evaluation of strength of ship structures, finite element analysis using beam elements is carried out as a rule. In beam modeling of ship structures, brackets are usually represented by rigid elements to simplify the analysis. The extent of rigid ends, which is called the span point, can be determined from the three kinds of view points, i.e., bending, shearing and axial deformation.
In this paper, a novel beam element is developed. The developed novel beam element, referred to as the rigid-ended beam element, can consider the effect of three kinds of span point within one element, which was impossible in modeling with the ordinary beam element. Calculated results agree with the exact solution for a cantilever beam and also with results obtained from finite element analysis using membrane elements. Structural analysis using the rigid-ended beam element is revealed to have good computing efficiency due to the elements not needing to correspond to the brackets. 相似文献
17.
Taek S. Jang S.H. Kwon Takeshi Kinoshita 《Journal of Marine Science and Technology》2005,10(4):181-187
A new mathematical formulation for the realization of nonlinear wave profiles and its nonlinear solution procedure, based
on the Banach fixed-point theorem, is proposed. To apply the formulation, a nonlinear equation for the Stokes wave in a finite
depth was derived, and some numerical solutions are given. A numerical study showed that the proposed iteration method, based
on linear progressive wave potential only, enabled us to realize the Stokes nonlinear wave profiles in a finite depth. The
nonlinear strategy of iteration has a very fast convergence rate, i.e., only about 6–10 iterations are required to obtain
a numerically converged solution. 相似文献
18.
The motions of an infinitely long, two-dimensional runway subjected to the dynamic moving load imposed by an airplane taking
off are investigated. The runway is assumed to be floating in an inviscid fluid and is initially at equilibrium before the
plane takes off. The deformation of the runway resulting from the take-off is wave-like and moves in the same direction as
the plane. The maximum drag occurs when the plane catches up with the first wave. Three different runway configurations were
considered: a baseline and ones which were ten and one hundred times more flexible than the baseline. For these runways, the
added drag to the aircraft was very small, ranging from 1% for the stiffest to 10% for the most flexible runway. 相似文献
19.
J. Kim J. Jang K. Lee Y. Lee S. Lee S. Oh 《International Journal of Automotive Technology》2014,15(2):183-189
Recently, biodiesel has emerged as an alternative fuel for achieving low-temperature combustion (LTC). Several articles in the literature have showed that oxygenated biofuels, including biodiesel, can improve combustion stability under high exhaust gas recirculation (EGR) operation, which is considered to be necessary for the removal of nitric oxides (NOx). The objective of this study was to investigate the performance and emissions of 20% biodiesel blended diesel fuel (B20) at various intake pressures and oxygen concentration levels to characterize the fuel for LTC application. The experimental investigation of B20 was carried out using a single-cylinder engine (SCE) at 1400 rpm and 50% load condition. A set of critical flow orifices with synthetic EGR was employed to simulate various intake pressures and EGR levels. The behavior of the B20 was first characterized under various intake conditions. The results showed that with high oxygen intake, B20 exhibited combustion and emission levels that were very similar to conventional diesel. However, B20 reduced combustion deterioration while exhibiting lower carbon monoxide (CO) and hydrocarbon (HC) emissions than diesel under low oxygen intake conditions. 相似文献
20.
D. K. Park C. D. Jang S. B. Lee S. J. Heo H. J. Yim M. S. Kim 《International Journal of Automotive Technology》2010,11(4):489-494
This paper presents a design technique to optimize the shape of a vehicle bumper beam that satisfies both the safety requirements
for a front rigid-wall impact and the regulations protecting pedestrians from lower leg injuries caused by bumper impacts.
An intermediate response surface modeling (IRSM) technique was introduced to approximate the non-linear force-displacement
curves obtained from the front impact analysis of a vehicle bumper. The accuracy of the IRSM model was tested by comparing
its results with those of the non-linear finite element analysis. The maximum displacement error between the two models did
not exceed 3%. Using pedestrian impact analyses based on the experimental arrangement of the Plackett-Burman design, the approximate
functions describing the response values acting on the lower legs were calculated. The shape of the bumper beam was optimized
by integrating the IRSM with the force-displacement model and the approximate functions on lower leg impact. The optimization
results satisfied safety regulations on the maximum allowable displacement of the vehicle bumper, and also the regulations
protecting pedestrians from lower leg injuries caused by bumper impacts. 相似文献