• Journal of the Korean Society of Safety
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• v.13 no.4
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• pp.34-40
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• 1998

It is very important to have exact informations on the properties and characteristics of the sintered steel as a new material of machine elements. The bending fatigue tests are performed for sintered steel bend specimens and spur gears, which are notched by using a slicing blade. The fatigue test at a constant stress amplitude is performed by using an electrohydraulic servo-controlled pulsating tester. Consequently, the S-N curves are obtained and the fatigue strength is compared with flaw depth. Accordingly, this study presents the fatigue strength of sintered spur gears, the critical notch depth of sintered steel and the effects of flaw depth on the bending fatigue strength. The enhancement of fatigue strength due to carburized treatment is clarified.

• Journal of the Korean Society of Safety
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• v.12 no.3
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• pp.30-37
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• 1997

This paper deals with the residual stress of carburized spur gears is calculated being on the assumption that the main cause of residual stress is the volume difference between case and core due to the martensitic transformation in cooling. A formula is proposed to estimated the residual stress from the hardness and the amount of retained austenite. The estimated residual stress is close to the stress measured by X-ray method. The estimated residual stress is applied to the analysis of the fracture mechanics of carburized spur gear teeth. The stress intensity factor due to the residual stress is demonstrated. The stress intensity factor is computed by the influence function method, and it is shown that the factor is decreased by the residual stress in Carburized gear tooth.

• Journal of Fisheries and Marine Sciences Education
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• v.22 no.3
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• pp.354-361
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• 2010

Author investigated the distribution of debris by a bottom trawler in the eight sea stations over the sea between Busan and Jeju island. 2,118 debris in number and 2,401.5kg in weight were collected. Most of collected debris were fishing gears which seemed to be lost or discarded during operations, and also most of the fishing gears was an eel pot. The densities of debris per hectare in number and weight were 1.21pieces and 2.639kg respectively. Station A was the highest densities compared to other stations, showing 2.7pisces and 4.9kg per hectare in number and weight. The closer to Busan it is, the higher density of debris can be collected.

• Tribology and Lubricants
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• v.25 no.6
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• pp.399-403
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• 2009

The objective of this paper is to predict pitting initiation by using a contact analysis and subsurface stress. Contact stresses are obtained by contact analysis of a semi-infinite solid based on the use of influence functions. Subsurface stress field is obtained using rectangular patch solutions. It is used Mesoscopic multiaxial fatigue criterion to predict contact fatigue life. It is important to predict pitting initiation to enhance reliability of the mechanical elements. Pitting life prediction in the spur gears which are fundamental mechanical element is presented in this paper.

• Tribology and Lubricants
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• v.29 no.6
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• pp.378-385
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• 2013

An epicyclic gearing system is compact and lightweight. However, it is difficult to share the driving force equally because the system has closed gear trains with multiple driving points, and it always has geometrical errors in the elements. Thus, in the case of planetary gears, the first problem is how to distribute the load evenly to the numerous planets. The method widely used abroad for this purpose is to utilize the elastic deformation of the components of the structure. However, the deflection is very complicated, and it is very easy for vibration problems to occur because of the decrease in the natural frequencies. Therefore, to equalize the load on the planets, this paper discusses the principle and theory behind the functioning of a floating intermediate ring. This magnifies the displacement of a planet's center arising from the equilibrium of the load and the lubricating film pressure, which improves the compliance of the planets. The results show that load equalization of the planets is possible through this improvement in their compliance.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2003.10b
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• pp.63-66
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• 2003

Forged gears have the obvious advantages with the greater utilisation of raw material and high productivity over the machined gears. The forged bevel gear has been used in differential gear for automotive with a high reliance. On the other hand, the studies have been continued to improve the accuracy and expand the applying areas. In this paper, a whole manufacturing process for forged gear from die design and cold forging to heat-treatment was introduced. The stress and elastic deformation for forging die have been analysed by the 3D-FEM-package. The real elastic deformation of die was measured by the strain-gages. The elastic deformation of die was reached to 1mm, in terms of the present study. The analysed quantitative dimension of die was taken into consideration into the CAD/CAM data for forging die.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2003.10b
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• pp.10-17
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• 2003

The amount of production orders from Japanese car and construction machine industries have slightly increased in 2002, but the costs of the forged parts have decreased due to severe competitions with the other Asian countries. Most of the forging industries and some universities are making more efforts for technological researches and developments to meet the demand for higher accuracy and higher quality products, shortening of delivery time, and development of forged parts for new industrial fields. Some helical gears of which surfaces can be net-shaped have been started for commercial base production to be shipped to car industries. Some non-graphite lubricants for hot forging and some conversion coating free lubricants for cold forging have been developed to improve some environmental problems.

• Proceedings of the KSME Conference
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• 2001.11a
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• pp.579-583
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• 2001

Cause of noise/vibration for the sheet feeding apparatus of digital MFP is investigated by analyzing the measured sound pressure and the strategy for reducing the noise level is suggested. Factors related to the noise/vibration are found by loading test and the measurement of the noise by assembling the components. By checking the center distance between gears and the boss height, precision of assembly is identified as a main factor of noise. From the result of analysis, it can be concluded that the noise level of sheet feeding apparatus can be reduced by maintaining the distance between gears and the precision of assembly adequately.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.217-220
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• 2001

We have developed the gear sound recognition system of mechanical timer. A mechancal timer is superior in endurance to electronic timer. So it is reliable under severe operating environment. It is putting together several kind of gears. Therefore when the timer operates, it emits mechanical sound of gears. We have chosen a microphone to detect the gear sound. A microphone is more efficient and convenient than other sensors. Because it is of low price and non-contact type sensor. For ease of measurement we designed real-time processing software based on graphical user interface.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.13 no.3
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• pp.103-110
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• 2014

In this study, spur and helical box models of an existing machine tool are investigated using structural and fatigue analyses. As the helical box model is shown to have less stress and deformation than those characteristics of the spur box model, the helical box has more strength and more transmission efficiency on the structure. In terms of fatigue analysis, the helical box model has more repeated fatigue strength than that of the spur box model. These study results can be effectively utilized in the design of real gear boxes of machine tools by anticipating and investigating prevention and durability against damage.