• Journal of the Korean Society for Precision Engineering
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• v.19 no.10
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• pp.202-211
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• 2002

The basic concept of 'tooth profile modification' to change a part of the involute profile to reduce the load in that area and appropriate profile modifications can help gears to run quietly and resist scoring, pitting and tooth breakage. In this study, the modification of tooth profile to make a smooth transmission of the normal loads in spur gears has been developed. The modified tooth profile has been determined by the total deflection at contact points. We use the AGMA Standard to design basic gear profile. We also developed a gear design program using tooth profile modification.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.3 no.3
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• pp.64-70
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• 2004

The sub-surface stress field beneath the spur gear's contact surface in lubricated condition has been analysed. The surface pressure was obtained by the elasto-hydrodynamic lubrication analysis using the accurate geometric clearances around the contact region of the teeth. The sub-surface stress field was calculated by using the Love's rectangular patch solution. The analysis results show that the sub-surface stress distribution is quite dependent on the surface pressure distribution. The pattern of sub-surface stress field is similar to that of the external load. The depth where the maximum effective stress occurs is not proportional to the intensity of the external load.

• The korean journal of orthodontics
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• v.2 no.1
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• pp.29-34
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• 1971

저자는 교정환자 치료에 흔히 사용되는 Light wire torquing auxiliary의 반경의 크기 및 교합면에 대한 spur 각도의 증감에 따라 Light wire torquing auxiliary 애서 발생되는 힘이 어떻게 변화하는 가를 Dentiform typodont 위에서 측정 관찰하여 아래와 같은 결과를 얻었다. 1) Light wire torquing auxiliary circle의 반경의 크기가 감소할 수록 발생되는 힘의 크기는 증가하였으나, 반경의 크기에 반비례하지는 않았다. 즉, Light wire torquing auxiliary circle의 반경을 20 mm.에서 10mm.로 하였을때 발생되는 force는 2배로 나타나지는 않았다. 2) 교합 평면에 대한 spur의 각도가 감소할 수록 force는 증가하였다. 이때 교합 평면에 대한 spur의 각도를 감소시킨 상태에서 교합 평면과 치아가 이루는 각도를 증가시켜 줌으로써 항속적인 힘의 증가를 나타냈다.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.04b
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• pp.183-186
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• 1995

A simulation method basee on upper bound method is developed in order to characterize forging characters in forging of spur gears. In this paer, utlizing a kinematically admissible velocity field and applying it to study the effect of inner diameter of holow billet. To predict the variation of inner diameter of hollow billet, neutal surface has been introduced into forging of hollow gears from hollow billes with flat punch. The neutral surface of each step is assumed as a circle and determined in order to have minimum forging energy by golden section method. According to the analysis, the magnitude of inner diameter of initial billet is vary important to reduce the relative pressure and forging load. And the variation of inner diameter of billet during spur gear forging is successfully predicted.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.8
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• pp.106-112
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• 1999

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 the sintered steel bend specimens of various densities 6.6 to 7.0 g/$cm^3$ and the sintered spur gear to consisted of Fe-Cu-C. 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. The fatigue strength S for fatigue life N of the specimen with the initial length of crack ai is simulated, and they are shown as N-S-A curves. This study investigate the crack growth characteristics by experiments and present crack growth simulation method for sintered gear

• Journal of the Korean Society for Precision Engineering
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• v.16 no.6
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• pp.148-159
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• 1999

A numerical method is presented for the dynamic analysis of spur gears rotating with very high angular speeds. For an efficient computation each gear is assumed to consist of a rotating rigid disk and an elastic tooth having mass, and finite element formulations are used for the equations of motion of the tooth. The geometric constraint is imposed between the rigid disk and the elastic tooth to fix them, and contact condition is imposed between the meshing teeth of the gears. At each iteration of each time step the Lagrange multiplier and contact force are revised by using the constraint error vector, and then the whole equations of motion are time integrated with the given Lagrange multiplier and contact force. For the accurate solution the velocity and acceleration constraints as well as the displacement constraint are satisfied by the monotone reductions of the constraint error vectors. Computing procedures associated with the iterative schemes are explained and numerical simulations are conducted with the spur gears.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.2
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• pp.223-230
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• 2003

Stress patterns are created in the plastic spur gear tooth body by introducing a hole or a steel pin to improve stress distribution. Static analysis using finite element method is carried out to show the effect. The result shows that maximum stress as well as tooth tip displacement is dependent on the size and location of a hole or a steel pin. When a hole located on the tooth center line, the maximum static stress level and the tooth tip deflection is always higher than that of a solid gear. But, a considerable reduction in the maximum stress and tooth tip displacement is achieved by insertion of steel pin.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2002.10a
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• pp.3-10
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• 2002

This study proposed a technique for inverse problem, linear approximation of contact position and loading in single and double meshing of spur gear, using 2-dimension model considered near the tooth by root stress. Determine root stress is carried out for the gear tooth by finite element method and boundary element method. Boundary element discretization near contact point is carefully performed to keep high computational accuracy. And from those estimated results, the comparing estimate value with boundary element method value was discussed.

• Journal of the Korean Society of Industry Convergence
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• v.25 no.6_1
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• pp.941-952
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• 2022

In this study, additive manufacturing technology was applied to restore a planner miller that was unusable due to aging. The drive spur gear of the planner miller was inoperable due to many defects in the teeth. The shape of the defective gear teeth was restored by deposition of the defective teeth using the DED method. However, as the location of the deposition head and the location of the set origin became farther, the deposition shape was different from the modeling shape. Nonetheless, since the modeling of the deposition part was designed to be larger than the tooth shape of the original gear, it was possible to completely restore all gear teeth through post-processing. The arrangement interval of the flow lines of the deposition part was narrower than that of the substrate. The hardness of the substrate was 172 HV, and that of the deposition part was 345 HV, which was twice as high as that of the substrate.

• Journal of Species Research
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• v.12 no.1
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• pp.90-94
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• 2023

The morphology and infraciliature of three newly recorded Aspidisca species in Korea, two collected from the eastern coast and one collected from Jeju Island, were investigated in vivo and after protargol impregnation. The three species are as follows: A. dentata Kahl, 1928, A. hexeris Quennerstedt, 1869, and A. polystyla Stein, 1859. The three species are characterized by having a "polystyla-arrangement" of frontoventral cirri: 1) A. dentata is characterized by having a broadly rotund body shape, a distinct peristomial spur, and a dorsal thorn; 2) A. hexeris is characterized by a broadly oval body shape, four projections along the left margin of body, and the single peristomial spur; and 3) A. polystyla has the broadly rotund body shape, transverse cirri each split into several parts (especially in vivo), and lacking of the peristomial spur. Among them, A. dentata and A. polystyla are poorly known and lack morphological description based on silver staining. In the present study, we provide a brief diagnosis, remarks, and photomicrographs.