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19 pages, 10637 KiB

Open AccessArticle

A Study on the Determination Method of the Gear Reduction Ratio for Electric Trains Considering Drive Shaft Relative Damage and Motor Efficiency

by Soonhyun Kwon, Jongbok Jeong, Dongkyeom Kim and Wonsik Lim

Appl. Sci. 2024, 14(22), 10472; https://doi.org/10.3390/app142210472 - 14 Nov 2024

Viewed by 1487

Abstract

This study presents a method for determining the optimal gear ratio in electric trains by examining the effects of motor efficiency, wheel wear, and relative damage to the input and output shafts of the reduction gear. In electric trains, reduction gears and wheels are critical for converting the driving motor’s torque and determining the motor’s operational point, which in turn affects efficiency and durability. Over time, wheel wear from regular use and periodic profiling reduces the wheel radius, causing an effective increase in the gear ratio, which impacts the motor efficiency and load distribution across drivetrain components. This study models the dynamic behavior of the vehicle’s drivetrain system using MATLAB/Simulink and incorporates real-world data on wheel wear to address the problem. Through simulations with varying gear ratios, it analyzes changes in motor efficiency and uses Miner’s rule to assess the relative damage on the reduction gear’s input and output shafts. The results enable the identification of a gear ratio that balances motor efficiency and reduces cumulative fatigue damage, which is especially important for maintaining long-term drivetrain durability. This approach provides a systematic way to enhance the overall performance and lifespan of electric train systems by selecting a gear ratio that optimally aligns efficiency and durability. Full article

(This article belongs to the Section Materials Science and Engineering)

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22 pages, 5768 KiB

Open AccessArticle

Estimating Accident Reduction Rate after Maritime Traffic Safety Assessment Using Synthetic Minority Oversampling Technique and Machine Learning Algorithm

by Wolseok Won, Minjeong Lim and Wonsik Kang

Appl. Sci. 2024, 14(8), 3283; https://doi.org/10.3390/app14083283 - 13 Apr 2024

Cited by 1 | Viewed by 1228

Abstract

This study was focused on deriving the MTSA-related accident reduction rate (ARR) required to calculate the safety benefits before and after expanding the scope of the system. By performing spatial analysis using geographic information system technology, MTSA-related accidents were identified on maritime routes near both assessed and unassessed project sites from 2010 to 2014. Subsequently, by applying the synthetic minority oversampling technique to balance the data, the algorithm learned from the random forest using the operational data of coastal passenger ship operations and accident data near unassessed locations where MTSA is not implemented. Then, the trained model was applied to predict accident occurrence in the absence of MTSA near the latest operational information of coastal passenger ship operations at the assessed project sites. The MTSA-related ARR was then calculated by applying the actual accident occurrences during operation near the assessed project sites where MTSA was implemented. The MTSA-marine ARR calculated at 17.41% can be applied to the calculation of safety benefit for MTSA. The results of this study can provide quantitative evidence for the application of higher-level systems considering the burden on regulatory targets when improving MTSA or similar systems. Full article

(This article belongs to the Special Issue Applied Maritime Engineering and Transportation Problems 2022)

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11 pages, 530 KiB

Open AccessArticle

Serum Alkaline Phosphatase as a Predictor of Cardiac and Cerebrovascular Complications after Lumbar Spinal Fusion Surgery in Elderly: A Retrospective Study

by Ann Hee You, Dong Woo Han, Sung Yeon Ham, Wonsik Lim and Young Song

J. Clin. Med. 2019, 8(8), 1111; https://doi.org/10.3390/jcm8081111 - 26 Jul 2019

Cited by 9 | Viewed by 3141

Abstract

We retrospectively enrolled 1395 patients aged > 65 years undergoing posterior lumbar spinal fusion surgery and classified them into tertiles based on serum Alkaline Phosphatase (ALP) levels (<63, 63–79, >79 IU/L). The primary outcome was the incidence of 30-day major adverse cardiac and cerebrovascular events (MACCE; composite endpoint defined as the occurrence of ≥1 of the following events: new-onset myocardial infarction, stroke, or cardiovascular mortality). The incidence of the composite endpoint was the highest in the third serum ALP tertile (0.4% vs. 0.2% vs. 2.2% in the first, second, and third tertile, respectively, p = 0.003). Multivariate analysis showed that the third serum ALP tertile was an independent predictor of the composite endpoint of MACCE (odds ratio 4.507, 95% confidence interval 1.378–14.739, p = 0.013). The optimal cut-off value of preoperative serum ALP showing the best discriminatory capacity to predict postoperative MACCE (measured by receiver-operating characteristic curve analysis) was 83 IU/L (area under curve 0.694, 95% confidence interval 0.574–0.813, p = 0.016). Preoperative serum ALP levels were independently associated with the composite endpoint of postoperative 30-days MACCE. We suggest that serum ALP can be used as a biomarker to predict cardiac and cerebrovascular complications following lumbar spinal fusion surgery in elderly patients. Full article

(This article belongs to the Special Issue Anesthesia for the High-Risk Patient)

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6 pages, 488 KiB

Open AccessArticle

A Dry Clutch Control Algorithm for AMT Systems in a Parallel Hybrid Electric Bus

by Changwoo Shin, Moseong Kim, Chunhua Zheng, Wonsik Lim and Sukwon Cha

World Electr. Veh. J. 2012, 5(2), 469-474; https://doi.org/10.3390/wevj5020469 - 29 Jun 2012

Viewed by 1134

Abstract

A clutch is a mechanical device which provides engine torque to the drive shaft of a vehicle. A dry clutch control for AMT (Automated Manual Transmission) systems has been an important issue to improve fuel economy and drivability in hybrid electric systems. In this paper, we propose a dry clutch control system to apply to the parallel hybrid electric bus. In order to analysis dynamic performance of the target vehicle, a vehicle dynamic model including engine, clutch, motor, transmission and vehicle is designed. For gear shifting simulation, the shifting maps for the hybrid electric bus are applied from the analysis results of DP (Dynamic Programming) theory that is one of the optimal control methods. The shifting maps consist of a pure electric mode and a hybrid electric mode calculated by using driving cycles for commercial vehicles. From vehicle dynamic equations, the control algorithm for a dry clutch is organized by using feedback loops based on the value of an engine, a clutch speed, a clutch release travel and an estimated clutch torque. Simulations are performed to analyze the dynamic performance of the proposed clutch control system during gear shifting. As a result, the vehicle model with the designed clutch controller compares to one with only the lockup controller in energy dissipation during gear shifting. Full article

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