| 48001. |
- Lee, Dongpil, et al.
(författare)
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Combined Lateral and Longitudinal Control with Variable Reference Path for Automated Driving
- 2020
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Ingår i: Advances in Dynamics of Vehicles on Roads and Tracks. - Cham : Springer International Publishing. - 2195-4356 .- 2195-4364. - 9783030380779 ; , s. 1114-1120
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Konferensbidrag (refereegranskat)abstract
- This paper presents combined lateral and longitudinal trajectory control with variable reference path for autonomous vehicle. A longitudinal velocity controller is designed to determine whether the current velocity is appropriate for the real-time or planned path. A steering control algorithm has been constructed using Ackermann steering geometry based path tracking controller known as pure pursuit method. The pure pursuit algorithm calculates the steering angle using the characteristics of the Ackerman steering geometry of the vehicle. This algorithm is not suitable at high speed but robust against disturbance and is a good method to apply in normal autonomous driving situations. The risk of the current speed is analyzed through the predicted lateral acceleration. However, the predicted lateral acceleration will vary depending on the vehicle. Therefore, the accuracy of the predicted lateral acceleration is improved using an adaptive neural network algorithm. The proposed algorithm has been verified by computer simulation with two consecutive curvature roads in city driving. The verification results were quite satisfactory.
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| 48002. |
- Lee, Dong Hun, et al.
(författare)
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Computational models for the ultimate compressive strength analysis of a steel stiffened plate structure at cryogenic condition
- 2019
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The aim of the present study is to develop computational models for the ultimate strength analysis of steel stiffened plate structures under axial compressive loading and cryogenic condition. As the number of vessels fueled by liquefied natural gas (LNG) are increasing, there are potential hazards that LNG leaks to hull structures, leading to cryogenic condition with a temperature of -160 deg. C. Under extreme compressive loading, steel stiffened plate structures under cryogenic condition can exhibit brittle fracture before and after ultimate strength is reached. The authors have shown such an evidence through a physical model testing on a large scale steel stiffened plate structures, which was presented in a separate paper. In the present paper, computational models using nonlinear finite element method are developed to simulate the ultimate compressive strength behavior of steel stiffened plate structures at cryogenic condition, involving brittle fracture. The numerical computations are compared with test database obtained from the physical model testing.
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| 48003. |
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| 48004. |
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| 48005. |
- Lee, Dong Hun, et al.
(författare)
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Ultimate compressive strength of steel stiffened-plate structures triggered by brittle fracture under cryogenic conditions
- 2022
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Ingår i: Low-temperature technologies and applications. - : IntechOpen. - 9781839685859 ; , s. 67-90
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- This chapter presents a practical method to investigate the effects of brittle fracture on the ultimate compressive strength of steel stiffened-plate structures under cryogenic conditions. Computational models are developed to analyse the ultimate compressive strength of steel stiffened-plate structures, triggered by brittle fracture, under cryogenic condition. A phenomenological form of the material model for the high-strength steel at cryogenic condition is proposed, that takes into account the Bauschinger effect, and implemented into a nonlinear finite element solver (LS-DYNA). Comparison between computational predictions and experimental measurements is made for the ultimate compressive strength response of a full-scale steel stiffened-plate structure, showing a good agreement between them.
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| 48006. |
- Lee, Dae-Yong, et al.
(författare)
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Hull structural response prediction using distortion base modes
- 2021
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Ingår i: Developments in the Analysis and Design of Marine Structures - Proceedings of the 8th International Conference on Marine Structures (MARSTRUCT 2021). - London : CRC Press. - 9781032136653 ; , s. 556-562
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Konferensbidrag (refereegranskat)abstract
- The hull structure health monitoring system is attracting attention by many ongoing vessels to prevent possible failure of the hull structure. As one of these efficient monitoring methods, the conversion method based on the mode superposition assumption had been introduced (Baudin et al., 2013, Bigot et al., 2015). It has the advantage that once the modal amplitudes are determined, it enables to estimate lots of structural behavior such as hull girder loads or stresses of structural members in a simply way. In this research, a case study of applying the conversion method on floating production storage and offloading unit (FPSO) hull model is introduced. Furthermore, the empirical processes in the mode selection stage have been optimized with respect to the target performance accuracy. The validity of this modification is verified by several case studies.
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| 48007. |
- Lee, Elisabeth, 1980, et al.
(författare)
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A Comparative Study between Cone Crushers and Theoretically Optimal Crushing Sequences
- 2011
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Ingår i: Minerals Engineering. - : Elsevier BV. - 0892-6875. ; 24:3-4, s. 188-194
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Tidskriftsartikel (refereegranskat)abstract
- The supply of minerals, ores and aggregates are crucial for the continuous development of today’s society. With a rising world population, growing urbanization, and increasing standards of living, the performance and efficiency of existing crushers must be improved in order to meet the escalating demand on these products. The current paper thus presents a comparative study between existing cone crushers and theoretically optimal crushing sequences. Full scale experiments are conducted in order to examine the effects of Closed Side Setting (CSS), stroke, and eccentric speed on crusher output. The performance of the examined cone crusher is then compared against what is considered as theoretically optimal. The subsequent analysis shows that significant gains can be made in terms of both product yield and overall capacity by adjusting crusher operation depending on the conditions at hand, e.g. increasing the CSS while maintaining the same stroke or decreasing the eccentric speed. It is also shown that a mixture of breakages modes is more optimal than the sole application of one optimized breakage mode.
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| 48008. |
- Lee, Eunji, 1980, et al.
(författare)
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Development of Verified Innovation Process for Healthcare Solutions (VIPHS): A Stepwise Model for Digital Health
- 2023
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Ingår i: Studies in health technology and informatics. - 1879-8365 .- 0926-9630. ; 302, s. 736-740
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Tidskriftsartikel (refereegranskat)abstract
- Many digital health projects often stop in the pilot or test phase. Realisation of new digital health services is often challenging due to lack of guidelines for the step-by-step roll-out and implementation of the systems when changing work processes and procedures are needed. This study describes development of the Verified Innovation Process for Healthcare Solutions (VIPHS) - a stepwise model for digital health innovation and utilisation using service design principles. A multiple case study (two cases) involving participant observation, role play, and semi-structured interviews were conducted for the model development in prehospital settings. The model might be helpful to support realisation of innovative digital health projects in a holistic, disciplined, and strategic way.
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| 48009. |
- Lee, Elisabeth, 1980, et al.
(författare)
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Implementation of optimized compressive crushing in full scale experiments
- 2013
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Ingår i: Minerals Engineering. - : Elsevier BV. - 0892-6875. ; 43-44:Special Issue: SI, s. 135-147
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Tidskriftsartikel (refereegranskat)abstract
- Commonly used at the coarser end of the comminution process, cone crushers often operate as the final crushing stage in the aggregate industry, or as the supplier of feed material for HPGRs or ball mills in the mining industry. As such, the performance of cone crushers undoubtedly affects the performance and efficiency of the overall process. The aim of this study is therefore to implement theoretical optimizations of compressive crushing for two different applications. Three different prototypes of crushing chambers have been manufactured based on the conceptual designs obtained from theoretical optimizations. Tested in full scale experiments, the results for these prototypes (designed for aggregate production and mining operation) were subsequently compared to the measured data for the corresponding reference crushing chambers. The performed analysis suggests that the performance of cone crushers can be improved in terms of product yield as well as reduction ratio.
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| 48010. |
- Lee, Elisabeth, 1980, et al.
(författare)
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Implementation of Optimized Compressive Crushing in Full Scale Experiments
- 2012
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Ingår i: Proceedings of Comminution '12.
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Konferensbidrag (refereegranskat)abstract
- Commonly used at the coarser end of the comminution process, cone crushers often operateas the final crushing stage in the aggregrate industry, or as the supplier of feed material forHPGRs or ball mills in the mining industry. As such, the performance of cone crushersundoubtedly affects the performance and efficiency of the overall process. The aim of thisstudy is therefore to implement theoretical optimizations of compressive crushing for twodifferent applications.Three different prototypes of crushing chambers have been manufactured based on theconceptual designs obtained from theoretical optimizations. Tested in full scale experiments,the results for these prototypes (designed for aggregate production and mining operation)were subsequently compared to the measured data for the corresponding reference crushingchambers. The performed analysis suggests that the performance of cone crushers can beimproved in terms of product yield as well as reduction ratio.
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