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231.
J. D. Kee J. H. Rho K. H. Kim D. H. Lee 《International Journal of Automotive Technology》2014,15(5):741-747
The driving stability of a passenger car at high-speed and under crosswind conditions is affected by aerodynamic characteristics as well as their dynamic characteristics, suspension, and weight distribution. In this study, the total measuring system was thought up to understand the transient vehicle dynamics and aerodynamics with driver’s control inputs all together. The test results were taken from a full-scale wind tunnel test, a crosswind generator test and an on-road test. We investigated major aerodynamic parameters that affect the driving stability of passenger cars under crosswind effects such as overtaking, passing each other, natural crosswind, etc. The reaction rate of high-speed stability will be improved when we minimize the total lift, side force and especially the yawing moment. 相似文献
232.
In order to effectively solve modern automotive design problems including the results of nonlinear FEA and multi-body dynamics, a progressive meta-model based design optimization is presented. To reduce the number of initial sample points, two sampling methods are introduced. Then, for efficient and stable construction of meta-models, three metamodel methods are newly introduced which are numerically based on the singular value decomposition technique. To design a practical system considering manufacturing tolerances and optimizing multiple performances, a robust design optimization, 6-sigma constraints and multi-objective strategies are implemented when solving the approximate optimization problem constructed from the meta-models. Until the convergence criteria are satisfied, the initially developed meta-models are progressively improved by adding only one point that minimizes the approximate Lagrangian in the consecutive optimization iterations. Finally, one validation sample and four automotive applications are solved to show the effectiveness of the proposed approach. 相似文献
233.
234.
235.
Sejoon Kim 《Coastal management》2018,46(3):222-234
The release of captive dolphins (Tursiops aduncus) from South Korean marine parks, which occurred in 2013, 2015, and 2017, is described and evaluated for its usefulness for conservation of coastal ecosystems. The campaign to free the dolphins created a flagship species, uniting the efforts of national government agencies, local government, and NGOs. However, the Korean management agencies framed the release as a species-specific conservation intervention, while the NGOs brought forward welfare-based demands for the curtailment of cetacean captivity. We argue that the release of the Korean dolphins changed the policy climate, to facilitate two major policy changes: revision of anti-whaling regulations to prohibit capture of cetaceans for exhibit, and improvement of regulations for rescue, rehabilitation, and release of stranded marine animals. Tradeoffs between welfare and conservation concerns are described in terms of risk for the management agency, welfare for the animals, and feasibility of a continued commitment to maintain the viability of the dolphin stock in the wild. The release of captive animals to their native range relies on a single-species conservation focus which poses little risk for management agencies but does not guarantee their continued commitment. 相似文献
236.
In this study, we propose a method for estimating the amount of expansion that occurs in subsea pipelines, which could be applied in the design of robust structures that transport oil and gas from offshore wells. We begin with a literature review and general discussion of existing estimation methods and terminologies with respect to subsea pipelines. Due to the effects of high pressure and high temperature, the production of fluid from offshore wells is typically caused by physical deformation of subsea structures, e.g., expansion and contraction during the transportation process. In severe cases, vertical and lateral buckling occurs, which causes a significant negative impact on structural safety, and which is related to on-bottom stability, free-span, structural collapse, and many other factors. In addition, these factors may affect the production rate with respect to flow assurance, wax, and hydration, to name a few. In this study, we developed a simple and efficient method for generating a reliable pipe expansion design in the early stage, which can lead to savings in both cost and computation time. As such, in this paper, we propose an applicable diagram, which we call the standard dimensionless ratio (SDR) versus virtual anchor length (LA) diagram, that utilizes an efficient procedure for estimating subsea pipeline expansion based on applied reliable scenarios. With this user guideline, offshore pipeline structural designers can reliably determine the amount of subsea pipeline expansion and the obtained results will also be useful for the installation, design, and maintenance of the subsea pipeline. 相似文献
237.
In this study, we propose a method for estimating the amount of expansion that occurs in subsea pipelines, which could be applied in the design of robust structures that transport oil and gas from offshore wells. We begin with a literature review and general discussion of existing estimation methods and terminologies with respect to subsea pipelines. Due to the effects of high pressure and high temperature, the production of fluid from offshore wells is typically caused by physical deformation of subsea structures, e.g., expansion and contraction during the transportation process. In severe cases, vertical and lateral buckling occurs,which causes a significant negative impact on structural safety, and which is related to on-bottom stability, free-span, structural collapse, and many other factors. In addition, these factors may affect the production rate with respect to flow assurance, wax, and hydration, to name a few. In this study, we developed a simple and efficient method for generating a reliable pipe expansion design in the early stage, which can lead to savings in both cost and computation time. As such, in this paper, we propose an applicable diagram, which we call the standard dimensionless ratio(SDR) versus virtual anchor length(LA) diagram, that utilizes an efficient procedure for estimating subsea pipeline expansion based on applied reliable scenarios. With this user guideline,offshore pipeline structural designers can reliably determine the amount of subsea pipeline expansion and the obtained results will also be useful for the installation, design, and maintenance of the subsea pipeline. 相似文献
238.
In 1994, Townend proposed a method to calculate the relative changes in various wave characteristics and structure-related parameters due to sea level rise for regular waves. The method was extended to irregular waves by Cheon and Suh in 2016. In this study, this method is further extended to include the effect of future change in offshore wave height and the sea level rise. The relative changes in wavelength, refraction coefficient, shoaling coefficient, and wave height in nearshore area are presented as functions of the relative changes in water depth and offshore wave height. The calculated relative changes in wave characteristics are then used to estimate the effect of sea level rise and offshore wave height change on coastal structures by calculating the relative changes in wave run-up height, overtopping discharge, crest freeboard, and armor weight of the structures. The relative changes in wave characteristics and structure-related parameters are all expressed as a function of the relative water depth for various combinations of the relative changes in water depth and offshore wave height. 相似文献
239.
Cheul-Kyu Lee Yong-Ki Kim Phirada Pruitichaiwiboon Jung-Suk Kim Kun-Mo Lee Chang-Sik Ju 《Transportation Research Part D: Transport and Environment》2010,15(4):197-203
Carbon fiber reinforced plastic is applied to railway car bodies to lighten them and reduce fuel consumption. This study looks at recycling methods for carbon fiber reinforced plastic used in a car body of a tilting train. It looks at four types of recycling: acid, pyrolysis in oxygen and nitrogen, organic solvents and supercritical process under various operating conditions. It evaluates the environmental performance of the recycling methods in terms of footprints of energy consumption and greenhouse gas emissions. A simplified life-cycle analysis is applied focusing mainly on the recycling treatment system. Only acid and pyrolysis in oxygen were capable of passing the technical and recyclate quality criteria. The energy footprint by pyrolysis in oxygen is approximately six times greater than acids and greenhouse gas emissions are some five times greater than with the acid recycling method. 相似文献
240.
DongYoung Lee GyungNam Jo YunHo Kim Hang S. Choi Odd M. Faltinsen 《Journal of Marine Science and Technology》2011,16(3):323-330
In this paper, we investigated the effect of sloshing on the sway motions of two-dimensional rectangular cylinders in regular
waves, bearing in mind possible applications for LNG-FPSO and LNG-FSRU. First, we carried out experiments for two models with
different drafts, or the same draft but different filling ratios, in which the models were firmly connected to each other.
The sway motion was measured with a noncontact video camera. This is an extension of Rognebakke and Faltinsen’s work for a
single model (J Ship Res 47(3):208–221, 2003). It was found that the sway motion became small when the incident wave frequency was close to the lowest natural frequency
of each model. The sway motion greatly increased when the wave frequency was higher than this frequency. The measured data
were compared with numerical results obtained by a single-dominant multi-modal method; relatively good agreement was noted.
However, the numerical results deviated from the experimental results near the lowest natural frequency of the smaller model,
which was believed to be due to overturning waves, as observed during the experiment. Since this is out of the valid range
for the single-dominant multi-modal method, other, more appropriate, methods such as the multi-dominant modal method must
be applied instead. 相似文献