• Journal of the Korean Society of Manufacturing Process Engineers
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• v.21 no.9
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• pp.21-27
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• 2022

The rotorcraft engine gearbox transmits the power generated by the turboshaft engine to the rotor by reducing the rotational speed and increasing the torque. The core of the rotorcraft engine gearbox is lightweight performance, which requires maximum weight reduction within the range that meets various requirements and constraints. Therefore, lightweight design through gear macro geometry optimization is necessary. In this study, gear macro geometry optimization was performed to reduce the weight of a rotorcraft engine gearbox. NSGA-III was used for the optimization, resulting in a combination of the gear ratio and macro geometry that minimizes the weight of the total gear. In addition, the safety factor of the gears satisfied the given conditions.

• 한국신재생에너지학회:학술대회논문집
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• 2006.11a
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• pp.109-112
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• 2006

In the recent studies, various types of multi mode electric variable transmission for hybrid electric vehicle have been proposed. Multi mode electric variable transmission consists of two or more different type planetary gear hybrid powertrain system(PGHP), which can change its power flow type by means of clutches for improving transmission efficiencies. Generally the power flows can be classified into three different types such as Input split, output split nd compound split. In This paper, we present velocity and torque equations of the input-split powertrain and analyze its optimal Performances. There are six combinations of the input-split powertrain, each combination has various lever length. We find optimal planetary gear ratios for fuel economy and acceleration performance, and compare performances of each combination.

• Journal of Energy Engineering
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• v.24 no.1
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• pp.88-96
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• 2015

Gear pump has a simple structure high reliability, easy operation and maintenance, widely used as a source of hydraulic system of hydraulic. In general, the gear pump was designed using variety of variables, the variables through the analysis of the mass flow rate and efficiency. In this paper, three-dimensional flow of the gear pump, in order to produce the optimal design of product, analysis was performed by using commercial software ANSYS v15.0 CFX. And then, combination of design parameters selected by ANSYS was carried out to confirm the simulation result. The efficiency and mass flow rate of the gear pump were studied by varying its rotational speed and the clearance between the gear tip and the housing. In the simulation results, as the rotational speed were increased, the average mass flow rate and efficiency increased. Furthermore, as the clearance between the gear tip and the housing was increased, the average mass flow rate and efficiency decreased.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.48 no.12
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• pp.953-960
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• 2020

This paper presents an optimization of gear web design used in a main gear train of an engine reduction gearbox for a rotorcraft. The optimization involves the minimization of a total weight, transmission error, misalignment, and face load distribution factor. In particular, three design variables such as a gear web thickness, location of rim-web connection, and location of shaft-web connection were set as design parameters. In the optimization process, web, rim and shaft of gears were converted from the 3D CAD geometry model to the finite element model, and then provided as input to the gear simulation program, MASTA. Lastly, NSGA-II optimization method was used to find the best combination of design parameters. As a result of the optimization, the total weight, transmission error, misalignment, face load distribution factor were all reduced, and the maximum stress was also shown to be a safe level, confirming that the overall gear performance was improved.

• Journal of the Korean Society for Precision Engineering
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• v.23 no.4 s.181
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• pp.37-43
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• 2006

In this paper, an approach to adaptive finite element analysis of three-dimensional forging processes is presented with emphasis on remeshing. In the approach, an optimal tetrahedral element generation technique is employed and the mesh density is specified by the combination of the weighted normalized effective strain and the normalized effective strain rate as well as the weighted normalized curvature. The approach is applied to computer simulation of an enclosed die forging process of a bevel gear and its results are compared with its related experiments. It has been shown that the analyzed results are in good agreement with the experimental ones.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.24 no.5
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• pp.407-413
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• 2014

The diesel engine and reduction gear combination is one of the common propulsion system in a naval vessel. Since the diesel engine has torsional vibration caused by reciprocating motion of the mass and gas pressure force of the cylinder, high cycle torsional fatigue can be occurred. Therefore, ROK navy restricts the maximum stress of the propulsion shaft according to MIL G 17859D. In this paper, the root cause for the failure of the diesel engine and reduction gear connecting shaft occurred in typical naval vessel is investigated based on the measured bending and torsional moment according to MIL G 17859D procedure.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2005.10a
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• pp.99-102
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• 2005

An approach to adaptive finite element analysis of three-dimensional forging processes is presented in this paper. In the approach, an optimal tetrahedral element generation technique is employed and the mesh density is specified by the combination of the normalized effective strain and the normalized effective strain rate. The approach is applied to computer simulation of an enclosed die forging process of a bevel gear and its results are compared with experiments.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.36 no.2
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• pp.121-130
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• 2023

Finite element analysis is widely used to predict the structural stability and tooth contact performance of gears. This study focused on the effect of finite element modeling conditions of a spur gear on the simulation result and the model simplification. The gear body and teeth, teeth width, configuration of mesh, frictional coefficient, and simulation time interval (gear mesh cycle division) were selected for model simplification for gear analysis. The static transmission error during a single-gear mesh cycle was calculated to represent the performance of the gear, and the elapsed time was measured as a simplification factor. Contact stress distribution was also checked. The differences in maximum transmission error and elapsed time depending on the model simplification methods were analyzed. After all simplification methods were estimated, an optimal combination of the methods was defined, and the result was compared with that of the most detailed modeling methods.

• Transactions of the Korean Society of Automotive Engineers
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• v.18 no.2
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• pp.1-6
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• 2010

This study presents the practical design modification to improve the retracting performance of the pyro-typed high power pretensioner. 3 components of the pretensioner are redesigned and the usefulness of the design modification is verified by the experiment. During the pretensioning process, the gas blast generated from the gunpowder is transferred to the rack-pinion gear through the manifold. The rack-pinion gear is connected with the spool where the webbing is rolled up. According to the rotation of the pinion, the spool is turned and the webbing is winded. To help the gas blast flow well, the shape of the inner cross section of the manifold is changed. The spur gear design program is developed and used to find the best combination of the rack-pinion gear pair to increase the power transmission efficiency. The pinion guide is installed on the spool to prevent the vibration of the pinion. As a result of the experiment, the amount of the web retraction length is increased when every single design modification is applied. Therefore, the retracting performance of the pretensioner is considered to be improved if the presented design modifications are applied.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.2
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• pp.185-192
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• 2014

Planetary gear design is complex because it involves a combination of discrete variables such as module, integer variables such as the number of teeth, and continuous variables such as face width and aspect ratio. Thus, an optimum design technique is needed. In this study, we applied a genetic algorithm to the design optimization of a planetary gear. In this algorithm, tooth root strength and surface durability are assessed with fundamental variables such as the number of teeth, module, pressure angle, and face width. With the help of this technique, gear designers could reduce trial and error in the initial design stages, thus cutting the time required for planetary gear design.