• Aerospace Engineering and Technology
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• v.12 no.2
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• pp.221-229
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• 2013

To achieve the best performance, the concept of drag reduced and power increased Human Power Aircraft(HPA) was presented by analyzing the HPAs in the world. To participate the '2012 HPA competition' in Korea, the streamlined fuselage and the simultaneous use of hands and feet were introduced. Furthermore the CFD analysis and power unit design were performed to verify the concept. In order to make the best use of streamlined fuselage effect, the fuselage shape design is important and to supply the hand power to the power unit, the control system design is important, also the test flight is required for validation.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.6
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• pp.1060-1068
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• 2002

Compound continuously variable transmission(CVT) mechanisms are proposed, which can offer a backward mode, a geared neutral, an underdrive mode and an overdrive mode. They are composed of a 2K-H I type differential gear unit, a V-belt type continuously variable unit(CVU), a few friction clutches and gears, and not required of a starting device as a torque converter. Compound CVT mechanisms developed here present two distinct operating modes which are a power circulation mode and a power split mode. The transition of two modes takes place at the particular CVU speed ratio. For these CVT mechanisms, performance analysis related to speed ratio, power ratio and efficiency are executed and proven by experimental studies.

• International Journal of Precision Engineering and Manufacturing
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• v.6 no.1
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• pp.5-14
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• 2005

Continuously variable transmission (CVT) mechanisms combine the functions of a K-H-V type differential gear unit and a V-belt type continuously variable unit (CVU). For the 24 different mechanisms, 12 of them are power circulation modes while the other 12 are power split modes. Some useful theoretical formulas related to speed ratio, power flow and efficiency were derived and analyzed. These mechanisms have many advantages: they decrease CVT size and weight, increase overall efficiency, extend speed ratio range, and generate geared neutral. Compound CVTs were developed by combining the power circulation mode and power split mode, which can offer backward motion, geared neutral, underdrive and overdrive.

• Journal of the Korean Society for Precision Engineering
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• v.29 no.7
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• pp.770-777
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• 2012

This paper deals with the design and modal characteristics analysis of a drive-train for a paralleltype hybrid electric vehicle (HEV). The function of the drive-train system (DTS) in the HEV combines or divides the torque and velocity from the internal combustion engine along with the induction motor. The system consists of a compound planetary gear and unit's electromagnetic clutch to provide the operation modes such as Engine Only (EO), Electric Vehicle (EV), and Hybrid Electric Vehicle (HEV) modes. In order to investigate the characteristics of the velocity and torque flow for the system, dynamic models of the HEV with DTS are derived from the prototype DTS. The performance of the derived dynamic models is evaluated by both computer simulations and experiments according to each mode.

• Journal of Drive and Control
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• v.17 no.2
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• pp.19-27
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• 2020

The purpose of this study was to suggest design criteria for the HMT (hydro-mechanical transmission) of a 55 kW-class agricultural tractor, develop a simulation model, and evaluate its performance such as axle rotational speed, tractor speed, and power transmission efficiency. In this study, the HMT comprised a compound planetary gear and a HSU (hydro-static unit), and the compound planetary gear comprised two planetary gear sets. The HMT has three gear stages, and the maximum tractor speed was selected as 40 km/h. The simulation time was set at 2736 hours considering the lifetime of the tractor, and the simulation was performed for each gear stage at the engine-rated power conditions. As a result of the simulation, the axle rotational speeds for each gear stage were 39, 77, and 158 rpm, respectively. The range of tractor speed for each gear stage were 1.05-10.22 km/h, 10.74-20.17 km/h, and 20.70-41.40 km/h, respectively. The APE (absolute percentage gear) for the tractor's maximum speed between target value and simulation results were 2.20%, 0.85%, and 3.50%, respectively. Also, the power transmission efficiency for each gear stage were 0-75%, 72-81%, and 69-81%, respectively. The simulation results for the power transmission efficiency of the HMT were similar with the results of the previous research. This was a basic study on the development of the HMT for an agricultural tractor. In future studies, it is necessary to develop a tractor platform and evaluate the performance. The comparison between the simulation model and the HMT tractor should be performed.