• Tribology and Lubricants
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• v.26 no.4
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• pp.230-239
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• 2010

Mechanical face seal installed in boiler feedwater pump prevents leakage of working fluid using thin fluid film between stator and rotor. If the leakage of working fluid exceeds the allowable volume, serious malfunction of boiler feedwater pump will be happen. The thinner fluid film exists between stator and rotor, the less working fluid leaks out. However, if the thickness of fluid film is not enough, the wear of seal face will be increased. And it causes the decrease in life of mechanical face seal. Therefore appropriate design is necessary to maximize the performance and life of mechanical face seal. In this study, numerical analysis using finite volume method was conducted to investigate the static characteristics of wavy mechanical face seals which have 4 different wavy surface profiles on rotor. As a result, opening force, leakage volume of working fluid and friction torque were obtained. For the same minimum film thickness, the static characteristics of mechanical face seal were affected by the wavy surface profile which can change the thickness of working fluid film and pressure distribution.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.34 no.4
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• pp.333-338
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• 2008

The evaluation for the visage volume was performed with human and dummy face using PRIMOS $body^{(R)}$. Three researchers measured the dummy face attached different volume of clay (6.6 mL, 13.2 mL, and 19.8 mL). It is identified that the high correlation between measured values and real volume ($R^2=0.99$). The percent (%) of relative standard deviation (RSD) of the data was shown below 10%. In Gage R&R analysis, the percent of contribution, the percent of study variation and distinct categories values were 0.78%, 8.85%, and 15% respectively. Therefore this method was regarded as the good standard condition in aspect of reproducibility and repetitiveness of data. The face volume variation was measured by PRIMOS $body^{(R)}$ on the face in participated 10 healthy Korean women volunteers. Subjects used the product once a day for two weeks as night sleeping pack. After application of the test products, the 3D image data of face were taken 1 and 2 weeks later. We found the face volume was significantly decreased after using products. In conclusion, this novel non-invasive technique was useful in measuring and visualizing alterations in face volume as a consequence of certain treatments. This system will provide a rapid and precise analysis of 3D topographical information for face.

• Tribology and Lubricants
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• v.27 no.5
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• pp.240-248
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• 2011

Mechanical face seal installed in primary heat transport pump used for heavy water reactor prevents leakage of working fluid using thin working fluid film between primary seal ring and mating ring. If the leakage of working fluid exceeds the allowable volume, serious accident can be happened by the trouble of primary heat transport pump. The thinner fluid film exists between primary seal ring and mating ring, the less working fluid leaks out. On the other hand, if the thickness of fluid film is not enough, the life of mechanical face seal will be reduced by friction and wear. Therefore appropriate design is necessary to maximize the performance and life of mechanical face seal. In this study, numerical analysis using finite volume method was conducted to investigate the performance of mechanical face seals which have same deep straight groove and 11 different net coning values. As results, equilibrium clearance between primary seal ring and mating ring, leakage volume of working fluid, friction torque on sealing surface and stiffness of working fluid film were obtained. With increasing net coning value, equilibrium clearance and leakage volume increase, and friction torque and stiffness of fluid film decrease.

• Steel and Composite Structures
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• v.23 no.3
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• pp.251-261
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• 2017

In this paper, thermal effect on the vibration and stability of initially stressed sandwich plates with functionally graded material (FGM) face sheets is analyzed. Material properties of FGM face sheet are graded continuously in the thickness direction. The variation of FGM properties assumes a simple power law distribution in terms of the volume fractions of the constituents. The governing equations of arbitrarily initially-stressed sandwich plates including the effects of transverse shear deformation and rotary inertia are derived. The initial stress is taken to be a combination of a uniaxial extensional stress and a pure bending stress in the examples. The eigenvalue problems are formed to study the vibration and buckling characteristics of simple supported initially stressed FGM/metal/FGM plates. The effects of volume fraction index, temperature rise, initial stress and layer thickness of metal on the natural frequencies and buckling loads are investigated. The results reveal that the volume fraction index, initial stresses and layer thickness of metal have significant influence on the vibration and stability of sandwich plates with FGM face sheets.

• Tribology and Lubricants
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• v.28 no.2
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• pp.70-80
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• 2012

Non-contact type mechanical face seals installed in mechanical systems prevent leakage of working fluid using thin working fluid film between stator and rotor. For that purpose, various kinds of surface profiles, grooves and conings have been applied on seal surfaces of stator and rotor to generate hydrodynamic and hydrostatic pressure. The thickness distribution of working fluid film is one of important factors which affect the working performances of mechanical face seal, and it is strongly affected by the surface height profiles of stator and rotor. Therefore, appropriate design of surface height profiles of stator and rotor is necessary to optimize the working performances and life of mechanical face seal. In this study, numerical analysis using finite volume method was conducted to estimate the working performances of wavy mechanical face seals which have 36 coning combinations. As results, minimum thickness of working fluid film, leakage volume of working fluid and friction torque in static equilibrium condition of mechanical face seal, and stiffness of working fluid film were obtained. The results show that the working performances of mechanical face seal were affected by the coning combinations which can change the thickness distribution of working fluid film and pressure distribution in sealing region of mechanical face seal.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.42 no.5
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• pp.87-96
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• 2005

In this paper, a mesh simplification algorithm using face constriction is proposed which considers the conservation of the volume of a 3D model. The face constriction method replaces three vertices of the candidate triangle with a new vertex, removing four faces at once. We propose a modified method, compensating an existing method, of considering curvature in the decision of the removing order of triangles. We also propose a method of determining a new vertex replacing the candidate triangle, which reflects curvature difference of the three surrounding areas of the three vertices of the triangle, while conserving the volume. It is shown by simulation that the proposed method conserves the volume and shows good constriction performance comparable to the other methods.

• Korean Journal of Computational Design and Engineering
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• v.2 no.1
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• pp.28-34
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• 1997

A swept volume is a useful tool for solving various types of interference problems. Previous works have concentrated on sweeping an object along an arbitrary path, that results in complex algorithms. This paper concerns the volume swept by translating an object along a linear path. After analyzing the structure of the swept volume, we present an incremental algorithm for constructing a swept volume. Our algorithm takes O(n/sup 2/ *.alpha.(n)+T/sub c/) time where n is the number of vertices in the original object and T/sub c/ is time for handling face cycles.

• The Korean Journal of Physiology
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• v.14 no.1
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• pp.15-23
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• 1980

In an attempt to clarify the influence of lung volume and water temperature on the heart rate response during apneic face immersion in the trained athletes, 10 soccer players were studied while holding their breath as long as possible after full inspiration(TLC), full expiration(RV) or normal breath(FRC) with face immersion in water. The electrocardiogram(Lead II) was recorded before and during each manuever and compared with 20 control subjects. The results are summarized as follows; 1) Resting heart rate was significantly lower in the athletes than that of the control groups. 2) During apneic face immersion, severe bradycardia were observed in both groups and the heart rate was significantly lower in the athletes than that of the control groups. 3) The degree of the bradycardia (maximum percent reduction of heart rate, HRmax.) were inversely propotional to the lung volume and water temperature. In the above results, bradycardial response was more sensitive in the athletes than the control. It was suggested that diving bradycardia was related to the gas content in the lung and reflex from the cold receptor in the face.

• Transactions of the Korean Society of Automotive Engineers
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• v.15 no.2
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• pp.143-150
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• 2007

Ring and cylinder bore wear may not be a problem in most current automotive engines. However, a small change in ring face and cylinder bore diameter can significantly affect the lubrication characteristics and ring axial motion. This in turn can cause to change inter-ring pressure, blow-by and oil consumption in an engine. Therefore, by predicting the wear of piston ring face and cylinder bore altogether, the changed ring end gap and the changed volume of gas reservoir can be calculated. Then the excessive oil consumption can be predicted. Here, the oil amount through top ring gap into combustion chamber is estimated as engine oil consumption. Furthermore, the wear theories of ring and cylinder bore are included. The changed oil consumption caused by the new end gap and the new volume of oil reservoir around second land, can be calculated at some engine running interval. Meanwhile, the wear amount and oil consumption occurred during engine durability cycle are compared with the calculated values. The wear data of rings and cylinder bore are obtained from three engines after engine durability test. The calculated wear data of each part are turn out to be around the band of averaged test values or a little below. It is shown that the important factor regarding oil consumption increasement is the wear of ring face.

• Geomechanics and Engineering
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• v.29 no.3
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• pp.291-300
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• 2022

Tunnel boring machines combined with the earth pressure balanced shield method (EPB shield TBMs) have been adopted in urban areas as they allow excavation of tunnels with limited ground deformation through continuous and repetitive excavation and support. Nevertheless, the expansion of TBM construction requires much more minor and exquisitely controlled surface settlement to prevent economic loss. Several parametric studies controlling the tunnel's geometry, ground properties, and TBM operational factors assuming ordinary conditions for EPB shield TBM excavation have been conducted, but the impact of excessive excavation on the induced settlement has not been adequately studied. This study conducted a numerical evaluation of surface settlement induced by the ground loss from face imbalance, excessive excavation, and tail void grouting. The numerical model was constructed using FLAC3D and validated by comparing its result with the field data from literature. Then, parametric studies were conducted by controlling the ground stiffness, face pressure, tail void grouting pressure, and additional volume of muck discharge. As a result, the contribution of these operational factors to the surface settlement appeared differently depending on the ground stiffness. Except for the ground stiffness as the dominant factor, the order of variation of surface settlement was investigated, and the volume of additional muck discharge was found to be the largest, followed by the face pressure and tail void grouting pressure. The results from this study are expected to contribute to the development of settlement prediction models and understanding the surface settlement behavior induced by TBM excavation.