• 대한기계학회논문집A
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• 제24권7호
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• pp.1731-1739
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• 2000

The Vibration signals of a gear driving system is often associated with gear tooth faults. Many studies have been done on the detection of impulsive vibration signals, which characterize the breaka ge of a gear tooth. Also, most of the studies on gear fault diagnosis are only about the fault existence at one gear-pair. This study concerns on the several possible faults of a geared motor that has three gear pairs. The measurement and analysis on the vibration signals of a running geared motor shows the relationship between the gear faults and the vibration signals. This study also shows that adaptive interference canceling technique can be appropriately applicable to detect which gear-pair has the fault, and that wavelet is better than spectrogram to figure out the gear fault.

• 한국가스학회지
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• 제26권2호
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• pp.9-13
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• 2022

벨트나 체인을 이용한 감속기는 간단한 장치이긴 하지만 공간을 많이 차지하여 공간상의 제약이 있기 때문에 전동휠체어 구동부에는 부적합하다. 하지만 유성기어형태의 감속기는 동일 축에서 감속이 이루어지기 때문에 부피를 작게 할 수 있어 공간의 제약이 벨트나 체인형태의 감속기보다 덜하다. 따라서 본 연구에서는 수·전동전환이 가능한 휠체어의 구동부에 대한 연구를 통하여 유성기어형태를 이용한 감속기로 큰 추진력을 얻을 수 있는 구동부를 개발하였다. 그에 따라 감속기에 적용되는 유성기어의 치형을 Kisssoft 프로그램을 이용하여 설계를 진행하였다. 또한 기존 휠체어 바퀴에 적용 가능하도록 구동부의 설계를 진행하였고, 구동부의 수·전동 전환원리 및 작동원리에 대한 메커니즘의 최적화를 진행하였다. 연구내용을 토대로 하나의 선기어와 2개의 유성기어, 하나의 링기어를 갖는 유성기어 형태의 휠체어 감속기 구동부의 최종 설계 및 제작을 진행하였다.

• 한국기계가공학회지
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• 제16권4호
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• pp.69-75
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• 2017

In this study, the performances of five input split type hybrid electric vehicle sub-drivetrains were analyzed. The five sub-drivetrains consist of chain, helical gears and planetary gears. For the analyzing above five sub-drivetrains, the mathematical equations were derived. From the analysis, we found that the sub-drivetrain with chain shows slower acceleration performance and larger energy consumption on the city driving. And, the sub-drivetrain with only helical gear shows smallest energy consumption on the city driving. If the sub-drivetrain can change its gear speed, it shows fastest acceleration performance, but it has largest energy consumption on the city driving due to its additional auxiliary components.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2009년도 춘계학술대회 논문집
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• pp.60-63
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• 2009

Manufacturing technologies of micro spur gear and micro mold by micro PIM were studied with stainless steel feedstock. For molding of gears, micro mold with gear cavity of 1.2 mm in diameter was produced by wire EDM. The proper injection pressure was selected to 70bar by observation and measuring of shapes and shrinkage of gears before/after sintering. For fabrication of micro mold, a tiny polymer gear was produced by injection into the mold. Then, 316L feedstock was again injected/compressed on the polymer gear and debinded together with polymer gear followed by sintering. As a result, another metal mold with gear cavity reduced to about 20% was fabricated and through repetition of this process chain, micro gear mold with cavity about below 800 um was finally obtained. In reduction of size by injection/compression molding, height of gear tooth was shrunk more and the effort for decrease of roughness of micro cavity were carried out ultrasonic polishing and as a result, the roughness in cavity decreased from 3-4 um to about 200 nm.

• International journal of advanced smart convergence
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• 제9권3호
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• pp.199-206
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• 2020

A wheelchair is an essential rehabilitation assistant device for the movement of paraplegia patients and generally paralyzed patients who cannot walk normally. In particular, the applicability of the manual/motorized wheelchair is gradually increasing. Until now, decelerators using belt, chain and worm gears, etc have been widely used. However, a decelerator takes a large space although it is a simple device and thus is not ideal for the driving part of manual/motorized wheelchair. For these reasons, in this study we developed a driving part producing a large driving force through a decelerator using planetary gears rather than conventional worm gear-based decelerator. We designed the tooth profile of the planetary gears for decelerator using Kisssoft program, In addition, we designed the driving part so as to apply it to the wheels of conventional wheelchairs, and then optimized the mechanism for the principles of manual/motorized transposition of the driving part and the operational principles. Based on the results of this study, we finally designed and manufactured a driving part for wheelchair decelerator in the form of planetary gears with 1 sun gear, 2 planetary gears and 1 ring gear.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2003년도 The 8th Asian Symposium on Precision Forging ASPF
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• pp.147-151
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• 2003

In the study, the modeling strategies in connection with the quantitative prediction and improvement of product accuracy and quality are proposed. The analysis models are composed of process chain, geometry of die, interface conditions between die and workpiece, material parameters, forming velocity of machine, and so on. A 3D simulation platform, around the software MSC. Superforge, is built up for the applications in net-shape forming parts. Some results for bevel gear are shown to demonstrate the efficiency of the modeling system.

• 한국정밀공학회지
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• 제25권4호
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• pp.118-126
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• 2008

A new approach to the critical speed calculation of general multi-mesh gear chain system included bevel gear is presented. A transfer matrix mode! based on Hibner's branch method is developed and the natural properties of the branched rotor system are calculated with using the ${\lambda}$-matrix formulation. A Campbell diagram, in which the excitation sources caused by the mass unbalance of the rotors, misalignment and the transmitted errors of the gearing are considered, shows that, at the neighborhood of the operating speed, there are the two critical speeds amplifying the first mode and the eighth mode.

• 로봇학회논문지
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• 제14권4호
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• pp.245-250
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• 2019

Milli-scale crawling robots have been widely studied due to their maneuverability in confined spaces. For successful crawling, the crawling robots basically required to fulfill alternating gait with elliptical foot trajectory. The alternating gait with elliptical foot trajectory normally generates both forward and upward motion. The upward motion makes the aerial phase and during the aerial phase, the forward motion enables the crawling robots to proceed. This simultaneous forward and upward motion finally results in fast crawling speed. In this paper, we propose a novel alternating mechanism to make a crab-inspired eight-legged crawling robot. The key design strategy is an alternating mechanism based on double four-bar linkages. Crab-like robots normally employs gear-chain drive to make the opposite phase between neighboring legs. To use the gear-chain drive to this milli-scale robot system, however, is not easy because of heavy weight and mechanism complexity. To solve the issue, the double-four bar linkages has been invented to generate the oaring motion for transmitting the equal motion in the opposite phase. Thanks to the proposed mechanism, the robot crawls just like the real crab with the crawling speed of 0.57 m/s.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 추계학술대회논문초록집
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• pp.329.2-329
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• 2002

This paper presents an improved escalator dynamic model so as to reflect the experimental observation on the pseudo-resonance affected by load applied. The experimental evidence reveals that backlash of gearbox as well as sag of driving chain are most critical factors to the pseudo-resonance in escalators. The dynamic model effectively reflects vibration characteristics measured in real escalators with respect to different conditions of driving chain and the number of passengers. (omitted)

• 한국자동차공학회논문집
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• 제10권3호
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• pp.218-226
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• 2002

This study was carried out to develop continuously variable-speed transmission(CVT) fur an agricultural tractor. The full-toroidal variator mechanism with flour discs and six rollers was utilized as a device fur changing speed ratio continuously. In system layout design, the sizes of the roller cylinders and the end-load cylinder, which were critical factors for controlling the variator, were designed. The planetary gear unit and six pairs of the gear assemblies were designed to establish the maximum speed of the vehicle at 30 ㎞/hr. In addition, the hydraulic clutch, the silent chain, the hydraulic manifold and the electronic controller were designed. Based on the design, a prototype CVT was developed and tested. Test results show that the CVT developed in this study could successfully provide variable speed of the tractor.