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LOWER EXTREMITY INJURY OF VIETNAMESE PEDESTRIAN IN CRASH BY A SEDAN USING NUMERICAL SIMULATION
Phu Thuong Luu Nguyen,Hung Anh Ly,Thien Phu Nguyen 한국자동차공학회 2023 International journal of automotive technology Vol.24 No.1
Pedestrians are among the most vulnerable road users, who often suffer serious injuries in road collisions. Therefore, evaluating the injury of a pedestrian is absolutely necessary. This paper aims to evaluate the lower extremity injuries for Vietnamese people by numerical simulation using a Human Body Model (HBM) – Total Human Model for Safety (THUMS). Considering that the HBM has the anthropometrical and biomechanical properties of the North American and European bodies, it is required to scale it down to represent Vietnamese anthropometry. Furthermore, it is necessary to develop a scaling algorithm to scale the published lower extremity injury criteria to properly assess the injury risk of a Vietnamese. After a Vietnamese-sized HBM is obtained from the scaling procedure, its posture is adjusted to represent a walking pedestrian. A sedan is employed for simulating the pedestrian collision with the impact velocity ranging from 20 to 50 km/h. The car models are simplified to reduce computational time. The findings illustrate that the bending moment and resultant force of femur and tibia increase with respect to the impact velocity. The knee ligaments have been injured at high risk.
( Nguyen Phu-thien ),( Lee Young-chan ) 한국정보시스템학회 2017 情報시스템硏究 Vol.26 No.4
Purpose Customer Loyalty is the most important factor of customer relationship management (CRM). Especially in retailing industry, where customers have many options of where to spend their money. Classifying loyal customers through customers’ data can help retailing companies build more efficient marketing strategies and gain competitive advantages. This study aims to construct classification models of distinguishing the loyal customers within a Korean retailing company using data mining techniques with R language. Design/methodology/approach In order to classify retailing customers, we used combination of support vector machines (SVMs) and other classification algorithms of machine learning (ML) with the support of recursive feature elimination (RFE). In particular, we first clean the dataset to remove outlier and impute the missing value. Then we used a RFE framework for electing most significant predictors. Finally, we construct models with classification algorithms, tune the best parameters and compare the performances among them. Findings The results reveal that ML classification techniques can work well with CRM data in Korean retailing industry. Moreover, customer loyalty is impacted by not only unique factor such as net promoter score but also other purchase habits such as expensive goods preferring or multi-branch visiting and so on. We also prove that with retailing customer’s dataset the model constructed by SVMs algorithm has given better performance than others. We expect that the models in this study can be used by other retailing companies to classify their customers, then they can focus on giving services to these potential vip group. We also hope that the results of this ML algorithm using R language could be useful to other researchers for selecting appropriate ML algorithms.
Nguyen Minh Phu,Vo Tuyen,Tu Thien Ngo 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.7
The paper presents the effect of the Reynolds number, relative roughness height and relative roughness pitch on the heat transfer and pressure loss in a solar air heater. A novel absorber plate with metal shavings from the turning of a steel shaft is employed to reduce the cost of production and to be available for the manufacturing industry. The parameters studied ranged from 5000 to 25000 for the Reynolds number, from 4.7 to 9.4 for the relative roughness pitch (P/e) and from 0.26 to 0.43 for the relative roughness height (e/D h ). The results show that there are some characteristics that differ from the published studies. The optimum e/D h is 0.35 to obtain the highest thermo-hydraulic performance parameter, and the parameter increases with a decrease in P/e. Within the scope of the study, the maximum thermo-hydraulic performance parameter is approximately 1.5. The correlations between the Nusselt number and the friction factor are developed based on the experimental data. The results from the correlations and from the experimental data are fairly in agreement.
Computational fluid dynamics analysis for basement ventilation in case of a fire
웬반합,Trinh Thi Minh Nguyen,Phu Minh Nguyen,Tu Thien Ngo 한국마린엔지니어링학회 2020 한국마린엔지니어링학회지 Vol.44 No.4
The basement parking lot, which provides a certain number of car spaces for users, is an effective solution for parking in crowded cities. The required ventilation system design is generally based on the number of air changes per hour, provided by local authority standards. An appropriately designed ventilation system plays an important role in ensuring a safe environment for people in case of a fire. This study aims to establish the smoke spread behavior and tenability criteria for a car fire in a basement parking lot with a small area of 2,700 m2, by using Autodesk computational fluid dynamics 2019 software. The car-fire growth rate was assumed to be a low t-squared curve. For numerical analysis, a steady-state fire was adopted at the sixth minute of the curve. The completely developed heat release rate of the car fire was 4 MW. Two common ventilation systems–a ductwork system and a combined impulse and ductwork system–were used for the simulation. The ventilation system was designed to extract 10 air changes per hour. The results suggested that the two ventilation systems guarantee a safe route for evacuation through the ramp. Besides, the ductwork ventilation system performs better at preventing the smoke from spreading, as compared to the combined ventilation system, during 6 min after ignition.