• Journal of Mechanical Science and Technology
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• v.19 no.11
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• pp.1967-1974
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• 2005

The subsurface stress field caused by both normal loads and tangential loads has been evaluated using the rectangular patch solution. The effect of tangential loading on the subsurface stress field has been investigated in detail for both the cylinder-on-cylinder contact and a spur gear teeth contact. For the cylinder-on-cylinder contact, the subsurface stress fields are moved more to the direction of tangential loads and the positions where the maximum stress occur are getting closer to the surface with the increasing tangential loads. The subsurface stress fields of the gear teeth contact are expanded more widely to the direction of tangential loads with the increasing tangential loads. The friction coefficient of a gear teeth contact is low because they are operated in a lubricated condition, and therefore surface tractions in the EHL condition hardly affect on the subsurface stress field.

• Tribology and Lubricants
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• v.20 no.4
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• pp.190-196
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• 2004

The effect of tangential loading on the subsurface stress field has been investigated numerically. As tangential load increases, the subsurface stress field expands more widely to the direction of the tangential load. Places of the maximum shear stress and the maximum effective stress are getting closer to the surface with the increasing tangential load. The tangential load in an elasto-hydrodynamic lubrication condition is so low that it does not affect the subsurface stress field.

• Journal of the Korea Furniture Society
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• v.17 no.1
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• pp.1-10
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• 2006

Movement behavior, shrinkage and equilibrium moisture content (EMC), in this experiment reflected a change of hygroscopicity mainly affected by continuously compressive load during radio-frequency/vacuum (RF/V) drying and humidity changes during equilibrating. As a result of interaction of the compressive load and moisture content changing under the RF/V condition, the shrinkages in loading direction were significantly increased while those perpendicular to loading direction were decreased. The shrinkages were affected most in tangential, and least in longitudinal direction. The shrinkages showed higher values in continuous drying than in intermittent drying. In the direction of increased shrinkage, all the movements were also increased, for example, the tangential movement for the loaded-RS and the radial movement for loaded-TS; in the direction of decreased shrinkage, all the movements except the tangential movement for the loaded-TS were decreased such as the tangential and radial movements for the loaded-ES, and the radial movement for the loaded-RS, comparing with those of the load-free. EMCs of the loaded specimens were all higher than that of the load-free specimen, and the highest for the loaded-TS, the lowest for the loaded-ES. The transverse hygroscopicity of specimen was reduced for the loaded-ES, but increased for the loaded-TS.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.04a
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• pp.856-860
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• 2008

Wire-suspensions in the conventional actuators mechanically support the moving part and guarantee the accuracy of the actuator without tangential tilt actuation. However, such a suspension configuration has considerable stiffness in the tangential tilt direction with two additional wire beams for the tangential tilt. Thus, we performed a design sensitivity analysis for the wire-suspension stiffness of 4-axis actuator and controlled the main parameters such as distance among wire-suspensions and wire-suspension length to allow tangential tilt flexibility. The elasticity of frame PCB that supports the moving part by wire-suspensions was also exploited to improve the flexibility of wire-suspension in the tangential tilt direction. A novel suspension structure was devised by establishing eight wire-suspensions at both sides of the moving part for electrical connection to coils. The magnetic circuit according to the proposed 4-axis actuator using multi-polar magnet and coils was also suggested for the generation of electromagnetic forces in the focusing, tracking, radial and tangential tilt directions.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.7
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• pp.1185-1192
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• 2003

Governing parameters for determination of the location of crack initiation and direction of crack initiation were investigated by performing fretting fatigue tests and analysis on Al 2024-T351. Fatigue tests were carried out using biaxial fatigue machine. It was shown that the dominant fatigue crack tended to initiate at the outer edge of one of the four bridge pads, growing at an angle beneath a pad, before turning perpendicular to the orientation of the axial load. Distribution of stresses generated during fretting fatigue loading along the interface was calculated by elastic FE simulation. It can be known that the location of crack initiation can be predicted by using the maximum tangential stress range. Futhermore, the crack initiation direction can also be predicted by a maximum tangential stress range.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2004.11a
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• pp.261-268
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• 2004

For cam and roller-follower contacting surfaces, the effect of tangential loading on the subsurface stress field at an elaso-hydrodynamic lubrication condition has been studied numerically. As tangential load increases, the subsurface stress field extended more widely to the direction of the tangential load. The positions of the maximum shear stress and the maximum effective stress are getting closer to the surface with the increasing tangential load. The tangential load at the elasto-hydrodynamic lubrication condition is of little consequence to the subsurface stress field.

• Transactions of the Society of Information Storage Systems
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• v.7 no.1
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• pp.19-24
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• 2011

Holographic Data Storage System, one of the next generation data storage devices, is a 2-dimensional page oriented memory system using volume holograms in writing and retrieving process. Recently photopolymer with disc type substrate was selected as a media for the Holographic Data Storage System. The disc tilt occurs when the media rotates and the external disturbance applies. The disc tilt causes the change of the angle between the reference beam and the media, the data cannot be retrieved with the right angle or other data page is retrieved. The tilt is generated in a 2-axis direction (tangential, radial). The tangential tilt direction is the same with the multiplexing plane, while the radial tilt direction is a perpendicular to the multiplexing plane. In this research we propose 2-axis tilt angle servo system. The tilt errors are measured by using external photo detector and the additional red laser. Then the tangential direction tilt is compensated by using the galvano mirror. Also the radial direction tilt is compensated by the rotating prism between the relay lens in the reference field. Finally we confirm the compensation results through the Signal to Noise Ratio(SNR) and Bit Error Rate(BER).

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.156-161
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• 2004

To predict the direction of the fatigue crack initiated from a hole under various types of biaxial fatigue loads with different phase difference and biaxiality, fatigue parameters were investigated. Axial and torsional biaxial fatigue loads were selected with the respective combination of five different phase differences of 0, 45, 90, 145 and 180 degrees and five biaxialities of 0, $1/{\sqrt{3}}$, 1, ${\sqrt{3}}$, ${\infty}$. Directions of the fatigue crack initiation around the hole were found to approach to the circumferential direction of the specimen with increment of the phase difference for fatigue tests with phase differences less than $90^{\circ}$. Whereas directions for tests with phase differences greater than $90^{\circ}$ went away from the circumferential direction and those were symmetric to the directions for tests with phase difference less than $90^{\circ}$. With increase of biaxilities, the fatigue crack initiated more apart from the circumferential direction of the specimen. These crack initiation direction were predicted using maximum tangential stress range and maximum shear stress range obtained at far-field and around the hole. Comparing these two stress parameters, The crack initiation direction can be successfully explained by using the direction of the maximum tangential stress range obtained around the hole and at far-field.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.8 s.179
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• pp.2123-2130
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• 2000

Radial immersion ratio is an important factor to determine the threshold in face milling and should be estimated in process for automatic force regulation. In this paper, presented is a method of on-line estimation of the radial immersion ratio using cutting force. When a tooth finishes sweeping, sudden drop of cutting forces occurs. This force drop is equal to the cutting force that acts on a single tooth at the swept angle of cut and can be obtained from cutting force signal in feed and cross-feed direction. The ratio of cutting forces in feed and cross-feed directions acting on the single tooth at the swept angle of cut is a function of the swept angle of cut and the ratio of radial to tangential cutting force. In the research, it is found that the ratio of radial to tangential cutting force is not affected by cutting conditions and axial rake angle. Therefore, the ratio of radial to tangential cutting force determined by just one preliminary experiment can be used regardless of the cutting conditions. Using the measured cutting force and predetermined ratio, the radial immersion ratio is estimated. Various experiments show that the radial immersion ratio and instantaneous ratio of the radial to tangential direction cutting force can be estimated very well by the proposed method.

• 한국연소학회:학술대회논문집
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• 2002.11a
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• pp.149-155
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• 2002

A promising new approach to achieve low pollutants emission and improvement of flame stabilities is tested experimentally using a hybrid cyclone jet combustor employing both premixed and diffusion combustion mode, Three kind of nozzles are used for LNG(Liquified Natural Gas) as a fuel. The combustor is operated by two method, One is ATI(Air Tangential Injection) mode, generated swirl flow by air as general swirl combustor, and the other is PTI(Premixed gas Tangential Injection) mode, The PTI mode consists of diffusion flame of axial direction and premixed cyclone flame of tangential direction in order to stabilized the diffusion flame. The results showed that the stable region of the PTI mode is more larger than the ATI mode. In addition, the reduction of NOx emission in PTI mode, as compared with that for the ATI mode is at least 50% in stable region. Also, even using the low calorific fuel as $CO_2$-blended gas, the cyclone jet combustor has high performance of flame stability.