• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 1997.10a
• /
• pp.210-215
• /
• 1997

Safety diagnosis on the driving system of electric train is performed using the vibration and noise signals of running railway train. Safety diagnosis is tried on the viewpoints of the appreciation of superannuation and the fault diagnosis of motor, reduction gear and boggie. The appreciation of superannuation is checked by the rms vibration levels of driving parts and the fault diagnosis is done by analyzing the frequencies of the vibration signals. The methods of measuring and analyzing the signals are decided on the basis of field 1-measured signals. The results shows that the vibration levels of each parts increase as the train goes older and each parts have their own frequency patterns of the vibration. As the results, the vibration and noise can be utilized successfully for the safety diagnosis of the driving part of electric train.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.25 no.7
• /
• pp.487-495
• /
• 2015

A generalized special program called planetary transmission analysis(here in after PTA) is developed to improve planetary gear noise in automatic transmission. PTA is capable of analyzing any typical one-degree-of-freedom automatic transmission gear train containing any number of simple, compound or complex-compound planetary gear sets. The kinematics module in PTA can compute the rotational speeds of gears and carriers and calculate the order frequencies to predict the planetary noise components. The power flow analysis module performs a complete static force analysis providing forces, moments, or torques of gears, bearings, clutches and connections. Based on the given type and number of planetary gear sets, the search algorithm determines all possible kinematic configurations and gear tooth combinations in a required set of gear ratios, while eliminating whole kinematic redundancies and unfavorable clutching sequences. By using PTA program, planetary internal speeds of new developed automatic transmission are early obtained; therefore, possibility of the noise problem could be predicted in early design stage. As implementing PTA in planetary gear NVH development procedure, planetary gear noise was successfully reduced by 10 dBA.

• Journal of Biosystems Engineering
• /
• v.25 no.6
• /
• pp.445-456
• /
• 2000

A can type high-speed transplanting mechanism was developed. The mechanism consists of a cam and an epicycle gear train with one sun gear in the middle and four planet gears in a row but symmetric with respect to the sun gear. Two planting knives are pivoted on the two outer gears. When sun gear rotates with a constant velocity the planting knife rotates also with a constant velocity. This constant motion of the transplanting knife is accelerated partially by a cam fixed in the gear housing so that the locus of the planting knife becomes similar to that generated by a crank-type transplanting mechanism. This cam-type transplanting mechanism can solve the problems associated with the rotary-type transplanting mechanisms. The mechanism was designed with an aid of computer simulation and proved applicable to high speed transplanters by its mock-up model. The design process of the mechanism was presented and dynamic analysis was also carried out to show the advantages of the mechanism over the rotary type high-speed planting mechanism.

• Journal of Ocean Engineering and Technology
• /
• v.37 no.4
• /
• pp.164-171
• /
• 2023

Vibration and noise must be considered to maximize the efficiency of a yaw system and reduce the fatigue load acting on a wind turbine. This study investigated a method for analyzing yaw-system vibration based on the change in the load-duration distribution (LDD). A substructure synthesis method was combined with a planetary gear train rotational vibration model and finite element models of the housing and carriers. For the vibration excitation sources, the mass imbalance, gear mesh frequency, and bearing defect frequency were considered, and a critical speed analysis was performed. The analysis results showed that the critical speed did not occur within the operating speed range, but a defect occurred in the bearing of the first-stage planetary gear system. It was found that the bearing stiffness and first natural frequency increased with the LDD load. In addition, no vibration occurred in the operating speed range under any of the LDD loads. Because the rolling bearing stiffness changed with the LDD, it was necessary to consider the LDD when analyzing the wind turbine vibration.

• Journal of the Korean Society for Railway
• /
• v.2 no.2
• /
• pp.13-20
• /
• 1999

The vibration signals of driving parts of electric train are distorted its signal patterns due to the impact components, which occurs when wheel passes rail joints. An elimination method of the impact components is investigated using adaptive signal processing technique in this study The result shows that adaptive interference canceling method seems to be more effective than line enhancement technique. The application of adaptive interference canceling method to the signal measured at bogie shows that the extractions of the signals of driving parts of traction motor, reduction gear, and axle bearing are successful. Therefore, only the signals of bogie, which is the place to attach an accelerometer easily, is sufficient for the fault diagnosis and the safety evaluation of electric train. Also, adaptive interference canceling method can be applicable to evaluate the performance of vibration isolation between bogie and car body and to investigate the characteristics of indoor sound.

• Proceedings of the KSR Conference
• /
• 2000.11a
• /
• pp.258-264
• /
• 2000

This study is to establish test method and evaluation technology of drive system appropriate to high speed train. The transmission system of high speed train serve in the severe condition compared with those of other trains, namely, they have to transmit high power to run with high speed and they have to make maximum use of the limited space. This paper reports the reviews and results for the test and evaluation method of reduction gearbox for high speed train and discusses various test items and methods about assembly and parts of gearbox transmission.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.64 no.12
• /
• pp.1718-1723
• /
• 2015

The diameter of the rotor of 2MW wind turbine is being developed by a number of companies with more than 80m, reliability and economic efficiency of the wind power generator has been improved. The need for large-scale wind turbine with excellent economy has been attracting attention because the new orders and the location of the wind turbine market has reached a limit. Technology development for enlargement of wind turbine is possible not only the improvement of energy efficiency but also reduce the construction costs per unit capacity. However, mechanical gearboxes used in wind generators have problems of wear, damage, need for lubrication oil and maintenance. Therefore, we want to configure the gearbox of a large-scale wind turbine using a magnetic gear in order to solve these problems of mechanical gearbox.

• Journal of the Korean Society for Precision Engineering
• /
• v.13 no.3
• /
• pp.123-131
• /
• 1996

This paper presents the development of an algorithm for the reliability and life of a hypoid gear axle system (located in the last section of power train) in heavy vehicles. The algorithm is developed about expecting the reliability and service-life for applied loads on each component in the system using the Weibull's probabilistic distribution and the extended Palmgren's model. The probabilistic method is used to results. Also this model is involved in predicting the failure which is related to the number of load cycles with the approaching load. Then the precious evaluation of the reliability and life in the axle system can be effectively carried out. Thus the general procedures of a reliability and life design, including the mathematical formulation and numerical examples, are illustrated for a hypoid gear axle system.

• Journal of the Korean Society for Precision Engineering
• /
• v.12 no.12
• /
• pp.173-179
• /
• 1995

This paper descrived housing design in conception of dynamic characteristics. The vibration and noise in power train system of automobile are important on the environment matter. The vibration caused by meshing teeth of gear is transmitted to the gear box faces through shafts and bearings. Shape of housing is used different radius of curvature(R=0 to 80 mm). The velocity responese, sound power and radiation efficency on the surface of gear box are calculated. The sound power and radiation efficency are compared with different radius of curvature.

• Wind and Structures
• /
• v.27 no.4
• /
• pp.255-267
• /
• 2018

This paper investigated the wind-snow flow around the bogie region of a high-speed train under crosswinds using a coupled numerical method of the unsteady Realizable $k-{\varepsilon}$ turbulence model and discrete phase model (DPM). The flow features around the bogie region were discussed and the influence of bogie fairing height on the snow accumulation on the bogie was also analyzed. Here the high-speed train was running at a speed of 200 km/h in a natural environment with the crosswind speed of 15 m/s. The mesh resolution and methodology for CFD analysis were validated against wind tunnel experiments. The results show that large negative pressure occurs locally on the bottom of wheels, electric motors, gear covers, while the positive pressure occurs locally on those windward surfaces. The airflow travels through the complex bogie and flows towards the rear bogie plate, causing a backflow in the upper space of the bogie region. The snow particles mainly accumulate on the wheels, electric motors, windward sides of gear covers, side fairings and back plate of the bogie. Longer side fairings increase the snow accumulation on the bogie, especially on the back plate, side fairings and brake clamps. However, the fairing height shows little impact on snow accumulation on the upper region of the bogie. Compared to short side fairings, a full length side fairing model contributes to more than two times of snow accumulation on the brake clamps, and more than 20% on the whole bogie.