• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1999.10a
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• pp.464-469
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• 1999

Recently, the need for designing multi-stage gear drive has been increased as the hear drives are used more in the applications with high-speed and small volume. The design of multi-stage gear drives includes not only dimensional design but also configuration design of various machine elements. Until now, however, the researches on the design of gear drives are mainly focused on the single-stage gear drives and the design practices for multi-stage gear drives, especially in configuration design activity, mainly depend on the experiences and 'sense' of the designer by trial and error. We propose a design algorithm to automate the dimension design and the configuration design of multi-stage gear drives. The design process consists of four steps. The number of stage should be determined in the first step. In second step, the gear ratios of each reduction stage are determined using random search, and the ratios are basic input for the dimension design of gears, which is performed by the exhaustive search in third step. The designs of gears are guaranteed by the pitting resistance and bending strength rating practices by AGMA rating formulas. In configuration design, the positions of gears are determined to minimize the volume of gearbox using simulated annealing algorithm. The effectiveness of the algorithm is assured by the design example of a 4-stage gear drive.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.14 no.4
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• pp.41-48
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• 2005

In recent years, the need for multi-stage gear drives which highly reduce output speed has been increased. However, the design of multi-stage gear drives has been carried out by a limited number of experts. The consideration for the direction of input and output axes also makes their design very difficult. The purpose of this study is to develop an algorithm for automatically generating complex multi-stage gear drives and to implement a design supporting system for multi-stage gear drives. There are 4 stages in the proposed algorithm, and major design parameters, such as the direction of input and output axes, reduction ratio, etc. are set up in the first stage. In the second stage, all mechanisms are generated, and various rules are applied to select feasible mechanisms. In the third stage, the gear ratio of each stage is divided from total gear ratio. Next, the specifications of gears for feasible mechanisms are calculated and their bending strength and surface durability are estimated. In the forth stage, appraised indexes are calculated and provided to support the estimation of the generated gear drives.

• Journal of Biosystems Engineering
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• v.43 no.4
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• pp.263-272
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• 2018

Purpose: The load on the planet gear of a planetary gear set is uniformly distributed. However, manufacturing and assembly errors cause uneven load sharing in the planetary gear set. To solve this problem, most studies have suggested applying a floating sun gear to the planetary gear set. However, the effect of the floating ring gear and floating carrier has not been extensively studied. This study aimed to investigate the effect of the floating ring gear. Methods: Two models were developed; one was the fixed ring gear model, and the other was the floating ring gear model. In the fixed ring gear model, the clearance between the ring gear and the housing was $0{\mu}m$, and in the floating ring gear model, the clearance was from $10{\mu}m$ to $100{\mu}m$. The load sharing of the planetary gear set was evaluated by the load sharing factor. Results: Our study showed that with increase in clearance, the load sharing factor of the planetary gear set approached unity. In addition, when the clearance increased above a certain level by which a fully floating ring gear was achieved, the load sharing factor was not affected by the clearance. Conclusions: This indicates that the fully floating ring gear increased the power density of the planetary gearbox by uniformly dividing the load of the planetary gear set. For this reason, the size of the gearbox could be decreased by using a fully floating ring gear.

• International Journal of Precision Engineering and Manufacturing
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• v.1 no.1
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• pp.62-70
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• 2000

The design of gear train is a kind of mixed problems which have to determine various types of design variables; i,e., continuous, discrete, and integer variables. Therefore, the most common practice of optimum design using the derivative of objective function has difficulty in solving those kinds of problems and the optimum solution also depends on initial guess because there are many sophisticated constrains. In this study, the Genetic Algorithm is introduced for the optimum design of gear trains to solve such problems and we propose a genetic algorithm based gear design system. This system is applied for the geometrical volume(size) minimization problem of the two-stage gear train and the simple planetary gear train to show that genetic algorithm is better than the conventional algorithm solving the problems that have continuous, discrete, and integer variables. In this system, each design factor such as strength, durability, interference, contact ratio, etc. is considered on the basis of AGMA standards to satisfy the required design specification and the performance with minimizing the geometrical volume(size) of gear trains

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.24 no.6
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• pp.470-475
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• 2014

In the past, transmission error(T.E.) has been identified as one of the main sources of gear whine noise, which cause serious passengers irritation at high frequency. In this study, to identify the correlation of the T.E. and gear whine noise, a T.E. measuring system was developed. By comparing the T.E. and gear whine noise level, T.E. target value which can represent the gear noise was proposed. The conclusions are followed: (I) It is possible to measure T.E. of the gear pairs (II) Similar trends are observed between T.E. and gear whine noise. (III) By observing the T.E. pattern, presence of sideband noise can be predicted. (IV) Proposed T.E. target value can be adopted to the gear manufacturing for gear noise quality management.

• Journal of the Korean Society of Industry Convergence
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• v.21 no.4
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• pp.159-165
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• 2018

In electric agricultural machine a reduction gear is needed to convert the high speed rotation motion generated by DC motor to lower speed rotation motion used by the vehicle. The reduction gear consists of several spur gears. Spur gears are the most easily visualized gears that transmit motion between two parallel shafts and easy to produce. The modelling and simulation of spur gears in DC motor reduction gear is important to predict the actual motion behaviour. A pair of spur gear tooth in action is generally subjected to two types of cyclic stress: contact stress and bending stress. The stress may not attain their maximum values at the same point of contact fatigue. These types of failure can be minimized by analysis of the problem during the design stage and creating proper tooth surface profile with proper manufacturing methods. To improve its life expectation in this study modal and stress analysis of reduction gear is simulated using ANSYS workbench based on finite element method (FEM). The modal analysis was done to understand reduction gear deformation behaviour when vibration occurs. FEM static stress analysis is also simulated on reduction gear to simulate the gear teeth bending stress and contact stress behaviour.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.13 no.1
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• pp.48-54
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• 2004

This paper describes the development of automatic shape design program for spur gear. It produces automatically third-dimensional surface and solid model used in CAD/CAM system with inputting simple measurements. This program can maximize user's convenience and get surface and solid model quickly as accepting GUI(graphic user interface). Automatic shape design program for spur gear was developed by Visual LISP, a developer program. Besides, a geometrical method and a mathematical algerian are used in this program. Use frequency of a fine spur gear is on the increase recently and manufacture process of this gear is heat treatment after press processing with molding. In this press processing, the upper punch portion of a fine spur gear shape is drafted by CAM. Therefore, estimated that surface and solid model of spur gear used to CAM are needed in this research. In this research, after 2 ㎜ gear was modeled by auto shape design program, the upper punch portion of a fine spur gear was manufactured as giving third-dimensional model to CAM software and then, displayed the result as applying to press process.

• Transactions of Materials Processing
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• v.21 no.1
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• pp.67-74
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• 2012

Although high productivity is possible, cold forged helical gears have not been widely used due to difficulty in achieving mechanical properties as well as dimensional accuracy of the product. Confidence in the gear characteristics also is very important in heavy-duty gear applications. Therefore, the properties of forged gears must be compared to the properties of conventional machined gears. The properties might be different due to the different fabrication processes. In this study, machined and forged products both before and after heat-treated have been compared by measuring the residual stress and involute curve of the tooth. Characteristics of hardness and microstructure were also compared. Additionally, tooth fracture strength was compared for the heat-treated products. Moreover, the tooth strength and the fracture pattern were compared between the machined and forged gears. The forged gear showed decreased changes in residual stress and decreased changes in dimensions when compared to the machined gear before and after heat treatment. The forged gear was over 10% better than the machined gear in tooth strength.

• Journal of Energy Engineering
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• v.25 no.3
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• pp.51-58
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• 2016

MLCC is key parts of many electronic products and mixer is used to make MLCC. Currently, non-contact mixer is increasingly used due to its many merits. In case of large capacity non-contact mixer, function of driving gear is important. In this study, therefore, in order to reduce manufacturing cost through optimal design of driving gear of large capacity non-contact mixer, study on shape optimization of driving gear without excessive design modification was performed. As the results, because safety factors of modification model were decreased about 3.0 ~ 3.5 times compared with those of model with robust design, the possibility for saving manufacturing cost was confirmed.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1997.10a
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• pp.292-297
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• 1997

The rattle noise is the most significant in many kinds of manual gearbox noises, which is generated at the idle stage of the engine operation. The main torsional vibration source of the driveline is the fluctuation of the engine torque. The gear rattle is impacts generating in the backlash of the free gear due to this torsional vibration. Many researchers reported the clutch torsional characteristic optimization method to reduce the idle gear rattle but only few of them give sufficient consideration to the system parameters like gear backlash, drag torque, system inertia, inertia distribution, engine torque fluctuation, idle engine rotation speed, and accessory load. This paper pays attention to the gear impact mechanism and system design parameters to reduce the idle gear rattle with computer simulation.