• 한국자동차공학회논문집
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• 제18권4호
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• pp.74-78
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• 2010

Turbocharger in the application to a diesel engine was widely used in automobile industries for the improvement of engine performance. To comply with stringent emission standards, ball bearing turbocharger has been developed by applying new emission reduction technology. Up to date turbocharger has been proved as an essential part of diesel engines by demonstrating its improved engine performance, fuel efficiency and reduced emission as well. In this research, the performance of the ball bearing turbocharger was compared by the conventional journal bearing type turbocharger. The results shows that ball baring turbocharger was proved to be 10~13% higher fuel efficiency and 30% less average emission than journal bearing turbocharger.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 1998년도 제27회 춘계학술대회
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• pp.241-245
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• 1998

The traditional approach is to characterize the behavior and performance of fluid film hydrodynamic journal bearings by means of linearized bearing analysis. The objective of this paper is to examine the nonlinear characteristics of the journal bearing when an external sinusoidal shock is given to the system. The oil film force is obtained by solving the finite width Reynolds equation at each time step by the solution of the column method. Frequency response functions obtained from both linear and nonlinear bearing simulations are compared with each other.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2003년도 춘계학술대회논문집
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• pp.100-106
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• 2003

In order to improve the instability of a plane journal bearing, the leaf spring dampers (LSD) are introduced. The effects of LSD on the stability of a plane journal bearing are investigated theoretically. The stability of a plane journal bearing with LSD are compared with the results of a plane journal bearing without LSD. And the effects of the asymmetry of the stiffness of the leaf spring damper on the stability of rotors are also investigated.

• 한국정밀공학회지
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• 제30권8호
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• pp.839-846
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• 2013

Because the performance of a reciprocating compressor in refrigeration and air-conditioning systems is influenced by the lubrication characteristics of sliding components, the lubrication characteristics between the crankshaft and journal bearing have to be researched for the design and the performance improvement of reciprocating compressors. Thus, the proper supply of lubricant for a lubrication between the crankshaft and journal bearing is essential, and an oil path for lubricant supply is installed in the shaft or bearing. However, in order to guarantee the lubrication performance of the journal bearing, it is necessary to design the position of the oil path. Therefore, it is studied to find the optimum position of the oil path by the analysis of the pressure distribution in the journal bearing. The results show that the position of the oil path is significantly influenced by the pressure distribution of the oil film in the journal bearing.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2013년도 춘계학술대회 논문집
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• pp.141-146
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• 2013

This research investigates the stability analysis for the rotating and the stationary grooved journal bearing. The dynamic coefficients of the journal bearing are calculated by using FEM and the perturbation method. When journal bearing is in whirling motion, the dynamic coefficients have time-varying components as a sine wave due to the reaction force of oil film toward the center of journal even in the steady state. The solutions for the equations of motion can be assumed as the Fourier series expansion. The equations of motion can be rewritten as the linear algebraic equations with respect to the Fourier coefficients. Then, stability of the grooved journal bearing can be calculated by Hill's infinite determinant. The periodic function of dynamic coefficients is derived using Fourier Fast Transform(FFT).The stability of journal bearing is determined as rotating speed increases and the stability of rotating grooved journal bearing is compared and discussed with the stability of stationary grooved journal bearing.

• Structural Monitoring and Maintenance
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• 제5권1호
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• pp.93-110
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• 2018

In order to provide a novel strategy for long-span bridge health monitoring system design, this paper proposes a novel ultimate bearing capacity ratios based bridge internal force monitoring design method. The bridge ultimate bearing capacity analysis theories are briefly described. Then, based on the ultimate bearing capacity of the structural component, the component ultimate bearing capacity ratio, the uniformity of ultimate bearing capacity ratio, and the reference of component ultimate bearing capacity ratio are defined. Based on the defined indices, the high bearing components can then be found, and the internal force monitoring system can be designed. Finally, the proposed method is applied to the bridge health monitoring system design of the second highway bridge of Wuhu Yangtze river. Through the ultimate bearing capacity analysis of the bridge in eight load conditions, the high bearing components are found based on the proposed method. The bridge internal force monitoring system is then preliminary designed. The results show that the proposed method can provide quantitative criteria for sensors layout. The monitoring components based on the proposed method are consistent with the actual failure process of the bridge, and can reduce the monitoring of low bearing components. For the second highway bridge of Wuhu Yangtze river, only 59 components are designed to be monitored their internal forces. Therefore, the bridge internal force monitoring system based on the ultimate bearing capacity ratio can decrease the number of monitored components and the cost of the whole monitoring system.

• 전기학회논문지P
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• 제60권2호
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• pp.82-90
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• 2011

The small precision spindle motors in the high value-added products including the visible home appliances such as DLP projector require not only the energy conversion devices but also high efficiency, low vibration and sound operation. However, the spindle motors using the conventional ball bearing and sintered porous metal bearing have following problems, respectively: the vibration by the irregularity of balls and the short motor life cycle by the ball's abrasion and higher sound noises by dry contact between shaft and sleeve. In this paper, it is proposed that the spindle motor with a fluid dynamic bearing is suitable for the motor to drive the color wheel of the DLP(digital lightening processor) in the visible home appliances. The proposed spindle motor is composed of the fluid dynamic bearing with both the radial force and the thrust force. The fluid dynamic bearing is solved by the finite element analysis of the mechanical field with the Reynolds equations. The magnetic part of spindle motor, which is a type of Brushless DC Motor, is designed by the electro-magnetic field analysis coupled with the Maxwell equation. And the load capacity and the friction loss of fluid dynamic bearing are analyzed to bearing clearance variation by the fabrication error in designed motor. The design of the proposed motor is implemented by the load torque caused by the eccentricity and the unbalance of the fluid dynamic bearing when the motors are fabricated in error. The prototype of the motor with the fluid dynamic bearing is manufactured, and experiment results show the vibration, sound, and phase current at no load and color wheel load of the motors in comparison. The high performance characteristics with the low vibration, the low acoustic noise and the optimal mechanical structure are verified by the experimental results.

• 대한족부족관절학회지
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• 제4권1호
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• pp.5-12
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• 2000

Purpose: The purpose of this study is to assess the amount of changes in the foot size on weight bearing in adult women, which might help in choosing an appropriate size of the shoes. Materials and Methods: The authors measured the length and width of the feet of 200 healthy women on weight bearing and non-weight bearing, and the size of the shoes they wore. Results: Foot length and width differences between right and left sides were 2.53 mm and 2.16 mm respectively on non-weight bearing, and 2.47 mm and 1.77 mm respectively on weight bearing. Foot length and width increased by 2.89% and 7.50% respectively on weight bearing than those on non-weight bearing. Shoe width was 6.82% longer and 9.54% narrower than the weight bearing foot size. There were 25 women who had shoe-related foot pain, all of them wore shoes that were 13.01 % or more narrower than the weight bearing foot width. Foot pain was significantly correlated with the shoe-foot width difference(p=0.0001). Conclusion: The foot size was increased by 2.89% in length and 7.50% in width with weight bearing. The width of their shoes was narrower. than the weight bearing foot width. Shoe-related foot pain was correlated with the foot-shoe width difference.

• 한국지반신소재학회논문집
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• 제13권2호
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• pp.41-47
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• 2014

헬리컬 파일은 나선형 원판이 부착된 철제 축과 나선형 원판이 모두 지지력을 발휘하기 때문에 지지력을 예측하는데 있어 기존의 일반적인 말뚝과는 다른 다양한 산정법이 적용되고 있다. 대표적으로 Individual bearing method, Cylindrical shear method, Torque correlation method가 사용되고 있다. 본 연구에서는 국내 지반에 시공된 중소구경 헬리컬 파일의 지지력을 예측하는데 있어 적절한 지지력 산정 방법을 검토하기 위해 연계논문의 현장 정재하시험에서 측정된 지지력과 3가지 방법으로 예측한 지지력을 비교 분석하였다. 비교 결과, 실측 지지력이 Individual bearing method와 Cylindrical shear method로 예측한 지지력의 최대값과 최소값 사이에 위치함을 확인하였으며, 상대적으로 Torque correlation method으로 예측한 결과가 실측지지력과 가장 유사함을 보였다.

• Tribology and Lubricants
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• 제15권1호
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• pp.108-115
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• 1999

The electrical and frictional properties of oil-impregnated sintered-metal bearing (OSB) and herringbone-grooved fluid bearing (HFB) with varying loads and speeds were measured. OSB shows very good performance up to 20,000 rpm and 0.05 N, and HFB successfully works up to 35,000 rpm and 0.05 N. From the endurance tests on start-stop and continuous operation, it was confirmed that those bearings could be mass-produced fur use on scanner motor in a laser scanner unit.