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Air Flow Analysis on Driving Truck with or without Side Pairing
Kyekwang Choi(최계광),Jaeung Cho(조재웅) 한국기계가공학회 2020 한국기계가공학회지 Vol.19 No.5
In this study, the overall states of the airflow when a truck with or without side pairing is driven at a maximum speed of 90 km/h, regulated by domestic law, were investigated through computational fluid dynamics numerical analysis. All the tested models showed that the airflow went under the truck body; specifically, the air did not flow along the underside to the rear of the truck but through the sides of its underside. The drag with the drag coefficient at model 3 was clearly higher than those for the other two models. The results of this study could help to improve the truck performance by reducing its resistance against the air flown from it in driving itself.
Durability Analysis due to Design Shape of Pinion Gear
Kyekwang Choi(최계광),Jaeung Cho(조재웅) 한국기계가공학회 2020 한국기계가공학회지 Vol.19 No.7
The structural analyses were conducted with three models of pinion gears connected to the rack gear which is driven by the steering axle at an automobile. Three models 1, 2 and 3 are designed as the different pinion gears due to the vehicle type. The lower the value of maximum stress, the better the durability of model. Model 3 has the best durability among three models. Models 1 and 2 are expected to require the adjustment in order to improve the durability better. By the utilization of this study result, it is thought to apply at designing the pinion gear with durability at the automobile.
A Study on the Efficient Flow Analysis due to Valve Shape
Kyekwang Choi(최계광),Jaeung Cho(조재웅) 한국기계가공학회 2020 한국기계가공학회지 Vol.19 No.6
This study investigates the flow efficiency based on valve shape. Three models are designed for the throttle, ball, and butterfly valves. Results show that Flow Model B, representing the ball valve, demonstrates the fastest flow rate among the three models. Although pressure contours are present on the side surfaces of the valve wings for all models, Flow Model C, representing the butterfly valve, demonstrates to be under the least amount of applied pressure among the three models. The results of this study can be utilized to efficiently control the air flow through various types of valves.
A Durability Investigation on Automotive Front Bumper Guard
Kyekwang Choi(최계광),Jaeung Cho(조재웅) 한국기계가공학회 2020 한국기계가공학회지 Vol.19 No.8
In this study, three models on the installation of automotive additional front bumper guard were designed and the structural analysis was carried out. The additional front bumper models B and C appears to be safer on stability instead of the basic front bumper model A. Model A with a simple structure is shown to have the safe region overall except in the area where the load is applied directly. Models B and C are shown to have the shortest lives at the regions where the bumpers are connected with each other. By comparing with the least fatigue lives at models A, B and C, Model B has the longest life with the best durability.
Flow Analysis due to the Slant Angle of a Windscreen at the Front of a Car Body
Kyekwang Choi(최계광),Jaeung Cho(조재웅) 한국기계가공학회 2020 한국기계가공학회지 Vol.19 No.9
In this study, CFX analyses were performed with flow models to minimize the flow resistance due to the windscreen on the front of a car body. The results indicated that the greater the slant angle of the windshield, the greater the maximum pressure area. The lower the slant angle of the windscreen, the smaller the area in which the air collides with the front of the car body and the more smoothly the air moves. The results of this study can be applied to increase fuel economy under driving conditions by changing the slant angle of the vehicle’s windscreen.
Flow Analysis near Shell Warhead
Kyekwang Choi(최계광),Jaeung Cho(조재웅) 한국기계가공학회 2020 한국기계가공학회지 Vol.19 No.2
The maximum speed and pressure distribution close to a warhead are altered based on the warhead shape, thereby resulting in changes to the flight distance and the destructive power. In this study, flow analysis was carried out based on the warhead shell shape. The maximum flow rate was detected at the side of shell, with a lower flow rate being found at the rear of the shell. In addition, the maximum pressure was detected at the warhead. It was also found that the reduction in the flow rate between the rear and the side of the shell in model A was smaller than that in model B. The obtained results are expected to be useful in the future design of shell warhead shape.
Flow Analysis according to the Installation of an Aero Part in a Sports Car
Kyekwang Choi(최계광),Jaeung Cho(조재웅) 한국기계가공학회 2020 한국기계가공학회지 Vol.19 No.1
In this study, flow analyses of a vehicle at driving were carried out after each installation of a tuning part, specifically the bonnet air ducts, the rear spoiler, and the rear diffuser. The study models were designed to comprise a total of eight cases in which each of the three parts were mounted individually or all together in vehicles. Assuming that the vehicle were driven with an average high speed of 100 km/h, the speed and pressure around the vehicle were obtained using CFD when driving. The rear diffuser that becomes the most effective among the three mounting parts has a major role in reducing air resistance.
Durability Analysis of Automotive Seat Frame by Shape
Kyekwang Choi(최계광),Jaeung Cho(조재웅) 한국기계가공학회 2020 한국기계가공학회지 Vol.19 No.3
The automotive seat appropriately absorbs the vibrations or shocks transmitted through a vehicle when it is in operation so as to provide a comfortable ride for passengers. In this study, the structural strength and durability of each model were investigated using structural analysis. The natural and critical frequencies at the seat were analyzed through vibration analysis. Through the results of this study on automotive seat frame models, the durability against the load and vibration is shown to be dependent on the configuration of the model.