• 한국생산제조학회지
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• 제21권2호
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• pp.305-310
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• 2012

Planetary gear box is a power transmitter having very high gear ratio in compact volume. The planetary step-down gear box converts high speed and low torque into low speed and high torque, which is widely used in constructional and industrial machinery field. And, the planetary step-up gear box does vice versa working, which is used as main gear box of large sized wind mill system. The large sized planetary gear box must be performed the normal-opposite rotation test as a its durability test for achieving the reliability. The large sized planetary gear box is composed by triple gear trains of sun gear, carrier, and ring gear. If input power is supplied into one of them and the other is fixed, and then another becomes the output part. In this paper, we designed a new test equipment which can do rapid normal and opposite rotational change with only small displacement by supplying test power using the above rotation (driving) characteristics and hydraulic cylinder and link, and also compared and analyzed with existing method through various experiments.

• 동력기계공학회지
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• 제16권2호
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• pp.5-10
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• 2012

The parking brake is one of the essential units embedded in track driving motor for forward and backward motion of an excavator. It is composed of multi-friction discs. When the hydraulic motor stops, the multi-friction discs closely stick to the facing discs by acting of multi-spring forces. So, the friction forces generate the braking force by compressing the cylinder barrel of hydraulic motor. In this study, we combined the multi-friction discs to two kinds of spring which have different spring force, and the maximum torque measured at the rotational starting point of hydraulic motor through gradually increasing the rotational torque of load side hydraulic motor by use of 1 and 2 sheets of friction plates. And, under this experimental condition, the maximum coefficient of static friction and the characteristics of paper friction sheet were analyzed. The obtained experimental results will be applied to the design of parking brake system for producing large size excavator in the 85-ton weight class.

• 한국기계가공학회지
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• 제9권3호
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• pp.83-88
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• 2010

This study aimed to enhance the durability by distributing the stress concentration at the contact and increasing the mechanical characteristics, as well as by changing the surface shape for LIP in the low-pressure seal among oil seals installed to the power steering of automotive. Accordingly, results were derived from comparisons and reviews with oil seals under the existing mass production by carrying out the performance tests after designs and productions are done with the addition of embo shapes on the surface of LIP in the low-pressure seal. As a result of this study, it has been identified that the durability of oil seals with the addition of embo shapes was enhanced with higher radial force and less variation in the internal diameter for the LIP. In addition, it was seen that the sealing ability for those oil seals is superior to the existing oil seals as their rotational torque values are less than those of the existing oil seals.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2011년도 추계학술대회 초록집
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• pp.33.2-33.2
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• 2011

The 'NREL Phase VI' model with a 10.06m diameter was tested in the NASA Ames tunnel to make a reference data of the computational models. The test was conducted at the one rotational speed, blade tip speed 38m/s and the Reynolds number of the sectional airfoils in that test was around 1E6. The 1/5 scale down model of the 'NREL Phase VI' model was used in this paper to study the power characteristics in low Reynolds number region, 0.1E6 ~ 0.4E6 which is achievable range for the conventional wind tunnel facilities. The torque generated by the blade was directly measured by using the torque sensor installed in the rotating axis for a given wind speed and rotational speed. The power characteristics below the stall condition, lambda > 4, was presented in this paper. The power coefficient is very low in the condition below the Re. 0.2E6 and rapidly increases as the Re. increases. And it still increases but the variation is not so big in the condition above the Re. 0.3E6. This results shows that to study the performance of the wind turbine blade by using the scaled down model, the Re. should be larger than the 0.3E6.

• 한국정밀공학회지
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• 제17권12호
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• pp.151-156
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• 2000

A vibration in a high-speed machine may lead to machinery malfunction and even catastrophic failure. So solving the vibration problem is a fundamental requirement for the stability of the high-speed machine. The flywheel energy storage system using superconducting magnetic bearings is a device to store electrical energy as rotational kinetic energy by motor and to convert it to electrical by generator when necessary. The high-speed rotating flywheel has large amplitude at a critical speed. And it has an unstable behavior by the electric torque at the first stage of the energy generation. In this paper, the stability analysis is performed with an analytical model and equations of motion-which is considered the effect of the electric torque-to identify the stable driving condition and the dynamic behavior.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.9-12
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• 2003

Brushless do motors have been replacing brush type motors in machine tool and robotics applications over the last number of years This Paper deals with the design and application of the slot-less permanent magnet synchronous motor (PMSM). The slot-less PMSM eliminates rotational cogging torque due to permanent magnet preferred positions decreases core loss and thus increases efficiency, provides excellent torque-to-volume and power-to-volume ratios, and has a linear current versus torque relation. The PMSM with slot-less stator is designed and manufactured, which will be used for high speed and high efficiency application such a medical instruments.

• 한국정밀공학회지
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• 제20권11호
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• pp.91-99
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• 2003

When the driver suddenly depresses the brake pedal under critical conditions, the desired trajectory of the vehicle can be changed. In this study, the vehicle dynamics and fuzzy logic controller are used to control the vehicle trajectory. The dynamic vehicle model consists of the engine, the rotational wheel, chassis, tires and brakes. The engine model is derived from the engine experimental data. The engine torque makes the wheel rotate and generates the angular velocity and acceleration of the wheel. The dynamic equation of the vehicle model is derived from the top-view vehicle model using Newton's second law. The Pacejka tire model formulated from the experimental data is used. The fuzzy logic controller is developed to compensate for the trajectory error of the vehicle. This fuzzy logic controller individually acts on the front right, front left, rear right and rear left brakes and regulates each brake torque. The fuzzy logic controlling each brake works to compensate for the trajectory error on the split - $\mu$ road conditions follows the desired trajectory.

• 조명전기설비학회논문지
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• 제20권9호
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• pp.84-89
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• 2006

This paper presents the thickness effect of hysteresis ring of hysteresis motor using finite element method combined with a vector hysteresis model. From the magnitude and direction of the magnetic field intensity, the magnetization of each ring element is calculated by a vector hysteresis model. The developed torque can be obtained with the vector sum of individual torque of each element on the hysteresis ring. From these calculations, it can be found that the motor torque is not in proportion to the thickness of the ring. As a result, there exists a proper point of thickness and that can be determined using the proposed methoㅇ in this paper.

• 한국공작기계학회논문집
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• 제16권5호
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• pp.70-76
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• 2007

The purpose of this study is to analyze the characteristics of a domestic developed hydraulic axial piston motor. An experimental apparatus was constructed and the output torque, the input oil pressure, the input flow rate, the speed of motor and oil temperature were measured. They were measured under both no load and load conditions. The results are as follows; 1. Motion of motor became steady state conditions after 5 seconds. 2. Output torque of motor was proportional to input oil pressure under both load and unload. 3. Speed of motor decreased with increasing load. 4. Oil temperature was almost constant. The results of this study will offer the basic data in designing and operating hydraulic axial piston motors.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 추계학술대회 논문집 학회본부 A
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• pp.9-11
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• 1999

This paper presents the problems of design and theoretical model of electrostatically driven axial-gap type wobble motor. The motor design benefits from large axial rotor-to-stator overlap and large gear ratios, and motor designs with rotor radii of 50 and $100{\mu}m$ are capable of generating torques in the [nNm] range at high electrostatic fields. Because of the large gear ratio, smaller angular steps and lower rotational speed are obtained, compared to radial-gap motor design. Aspects like gear ratio, torque generation, excitation schemes and torque coverage, normal forces, friction are addressed.