• Journal of the Korean Society of Safety
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• v.29 no.6
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• pp.28-33
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• 2014

Vibro ripper worked by high frequency vibration is developed to do rock fragmentation and work of ripper is the different concept with other existing breakers. The gear box-shank welded joint of vibro ripper is very important part to deliver vibromotive force to tooth, so this part should endure high frequency vibration environments. The purposes of this study are to choose the optimal welding conditions for fatigue strength. The conditions were made using three kind of shank materials and two kind of filler metals. Shank materials are Hadox-hituf, Posten80 and AR400, and filler metals are CSF-71T and CSF-81T. The fatigue test was conducted each condition. Fracture surface was observed to estimate fracture characteristics of welded joint using SEM.

• Transactions of the Korean Society of Automotive Engineers
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• v.16 no.4
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• pp.135-142
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• 2008

Hydraulic power steering system has been adopted in seniority passenger and commercial vehicle system for an easy maneuverability and a smoother ride. In this study, hydraulic power steering system analysis model which includes hydraulics and mechanical sub-systems was developed using commercial software, AMESim in order to predict characteristics for various steering components. Each component which constructs system was modeled and verified by experimentally obtained characteristics curves of each components. The parameter sensitivity analysis such as valve opening area, torsional stiffness of torsion bar for system design are carried out by the analysis and experimental method. The predicted results by the development model were a good agreement with experimentally obtained results. The sensitivity investigation results rotary torque when changing an input shaft edge width, was most sensitive, to change in angle and slot width and supply flow of input shaft edge is not a lot sensitively.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2013.04a
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• pp.373-378
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• 2013

Impact wrench has a sophisticated structure to implement various pre-designed mechanisms with specific functions. In the structure of impact wrench, the gear box has an important role to generate impacting force of anvil from actuating torque. Since, it requires to design systematically the gear box for accurate mechanism of operation and transferring motions. In this paper, a methodology of dynamic analysis, which is useful to design mechanical system, is proposed and applied to impact wrench, sequentially. At first, the way to perform dynamic analysis for design, which is progressed from component to assembled system, is introduced. Secondly, the proposed methodology is applied to designing impact wrench. Eventually, the results of parameter study with proposed methodology are applied to actual design for design optimization. And optimized-design is evaluated in the view of accurate operation and structural stability.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.15 no.2
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• pp.46-50
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• 2016

When rotating the clutch drum in the power take-off (PTO) gear box of an armored recovery vehicle, lots of inner oil is drained through the adapter by centrifugal force. Therefore, a lack of lubrication is caused by inner oil loss, and the bearing is damaged by overheating. This study, therefore, aims to design an oil-controlling adapter by using shape alteration to prevent oil loss. Both the original and improved adapters were tested at 1,800rpm by using an operational test machine. When applying the original adapter to the gear box, the bearing was damaged by overheating, which was caused by the lack of lubrication. When applying the improved oil-controlling adapter, on the other hand, it prevented the loss of inner oil. Applying the improved adapter is expected to prevent the overheating caused by lack of lubrication.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.23 no.4
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• pp.301-307
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• 2013

MRU(motor reduction unit) for KTX is a assembled complex structure that is equipped with a lot of parts at the express train KTX and that is the core power source operating variable speeds. This study is recorded the dynamic characteristics analysis results tested by EMA which is done through the parts and assembly test, transient analysis and stoped train test in order to design the online monitoring system for KTX MRU. And the mode shapes result from critical vibration frequency explain the relation with variable speeds of express train over 250 km/hr. Also these variable speeds make variable operational frequencies at pinion, axle gear mesh frequency and normal bearing fault frequencies. As the specified speed can make resonance with natural frequencies of the MRU, for the train operating stability, this study also presents the MRU's critical speeds calculated by the each train speed.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2010.10a
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• pp.124-129
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• 2010

Wind load characteristics is investigated for vibration analysis of wind turbine gearbox. A normal wind model assumed, of which the wind velocity is increased according to the height from ground. A blast wind model is assumed, of which the maximum velocity is located at the center and the velocity profile is normally distributed. The periodical torque and bending moments transmitted to the main shaft of wind turbine are investigated. The average values and the harmonic terms of the transmitted moments are studied on the wind direction of range $-45^{\circ}{\sim}45^{\circ}$ and the bending moment characteristics are examined, which is regarded as the main source of the misalignment of gear train.

• Journal of Applied Reliability
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• v.14 no.4
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• pp.208-212
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• 2014

An experimental gear-box was set-up to simulate the real situation of the wind-turbine. Artificial cracks of different sizes were machined into the gear. Vibration signals were acquired to diagnose the different crack fault conditions. Time-domain features such as root mean square, variance, kurtosis, normalized 6th central moments were used to capture the characteristics of different crack conditions. Normal condition, 1 mm crack condition, 2mm crack condition, 6mm crack condition, and tooth fault condition were compared using ANFIS and DAG-SVM methods, and three different DAG-SVM models were compared. High-pass filtering improved the success rates remarkably in the case of DAG-SVM.

• Proceedings of the IEEK Conference
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• 1998.06a
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• pp.487-490
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• 1998

During driving an automobile, drivers push the clutch and transmit gear by their feeling. At the automobile which have the manually operated gear box by using apart designed equipment, for get the semi-auto function, a lot of research to realize the system which have passive transmission and automotive transmission has developed. In this paper, basically using one chip .mu.-comcontrolled the clutch of automobile by means of LPF, F/V converter and TR driver circuit which is designed. In the past, it was controlled the motor by operating relay which is int eh output system to control the clutch. This system some noises is made by on and off the relay, lessen the motor speed and causes many error due to consume the large power on driving the motor. In this paper, to solve these problems the output TR is operated by using one chip .mu.-com decrease the electic power consumption and designed the actuator to control the clutch by measns of vacuum.

• Proceedings of the KSR Conference
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• 2009.05a
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• pp.688-694
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• 2009

As a drive system for next generation train, we have been making research and development of a direct drive traction motor system without the conventional reduction gear. This traction motor is expected to have many advantages such as low noise, reduced maintenance, and energy saving. Due to the demand for high-output motors in the limited space between the wheels, open-ventilating traction motors with gear box have been widely used for many years. However, a conventional open-ventilating traction motor is necessary periodical disassembly to remove the accumulated dust from open-air ventilation. Reducing this burden, as well as increasing energy efficiency and reducing noise, would benefit the next generation of traction motors. To address these needs, KRRI have been developing a fully enclosed type direct drive motor(DDM) with high-efficiency permanent magnet for the next generation train.

• 한국신재생에너지학회:학술대회논문집
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• 2006.06a
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• pp.319-322
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• 2006

Under the national project for the development of 2MW wind energy convert system, we are under development of the prototype of 2MW wind turbine with low speed gearbox. This system adopts low speed gear box with planetary and spur gear and is pitch regulated variable speed type with the synchronous permanent magnet generator. The compromised size of generator in diameter and width are adopted to meet the structural design requirements. In this paper, the concept study for the type, the aerodynamic design for the blade and the details of load calculation will be presented. The detailed characteristics of the system will also be introduced.