• Journal of the Korean Institute of Gas
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• v.28 no.1
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• pp.59-64
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• 2024

In this study, we conducted research on a miniaturized transmission system suitable for ultra-compact electric vehicles, such as electric arts or small electric cars. While conventional electric vehicles eliminate multi-gear transmissions and control motor output or secure initial driving force through reducers, in vehicles like electric karts or compact electric cars, which have relatively small battery capacities, the driving range can be reduced or the motor can be stressed epending on the loading state. Therefore, in this study, we developed a low stage ratio 0.625 and high stage ratio 1.6 a two-stage transmission system that can change gears as needed, considering factors such as slope conditions and loading status, by applying the continuously variable transmission (CVT) mechanism. Based on the selected gear ratios, we designed the transmission and created a test rig to verify the power transmission efficiency of the developed transmission. Using the test rig, we varied the rotational speed and load of the transmission to confirm its power transmission characteristics and also examined the heat generation characteristics during shifting and operation. As a result, developed a two-stage transmission with a CVT structure.

• Journal of Drive and Control
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• v.21 no.1
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• pp.22-30
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• 2024

Gearboxes designed for reciprocating motion operating mechanisms operate under conditions where both the load and speed undergo continuous variations. When conducting durability tests on gearboxes designed for such applications, operating the target gearbox under conditions similar to the intended usage is essential. The gearbox must be operated for the required number of cycles to validate its durability under conditions mirroring its intended usage. This study devised an accelerated test method for gearboxes, which reduces operating angles and operational strokes. The reliability of the accelerated test was verified by comparing the stresses imposed on the gears under general and acceleration conditions through multi-body dynamic simulations. The results confirmed that the maximum contact stress levels under normal and accelerated conditions were within a 0.1% error range, indicating a minimal difference in the gear damage rates. However, a difference in the maximum contact stress results between the normal and accelerated conditions was observed when inertial forces acted on the output shaft due to the operational acceleration of the gearbox. Therefore, when conducting this acceleration test, caution should be exercised to ensure that the operational load on the gearbox, which affects inertia, does not significantly deviate from the conditions observed under normal operating conditions.

• Journal of Biosystems Engineering
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• v.43 no.1
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• pp.1-13
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• 2018

Purpose: The development of compact tractors that can be used in dry fields, greenhouses, and orchards for pest control, weeding, transportation, and harvesting is necessary. The development and performance evaluation of power transmission units are very important when it comes to tractor development. This study evaluates the performance of a driving power transmission unit of a 50 kW multi-purpose narrow tractor. Methods: The performance of the transmission and forward-reverse clutch, which are the main components of the driving power transmission unit of multi-purpose narrow tractors, was evaluated herein. The transmission performance was evaluated in terms of power transmission efficiency, noise, and axle load, while the forward-reverse clutch performance was evaluated in terms of durability. The transmission's power transmission efficiency accounts for the measurement of transmission losses, which occur in the transmission's gear, bearing, and oil seal. The motor's power was input in the transmission's input shaft. The rotational speed and torque were measured in the final output shaft. The noise was measured at each speed level after installing a microphone on the left, right, and upper sides. The axle load test was performed through a continuous equilibrium load test, in which a constant load was continuously applied. The forward-reverse clutch performance was calculated using the engine torque to axle torque ratio with the assembled engine and transmission. Results: The loss of power in the transmission efficiency test of the driving power unit was 6.0-9.7 kW based on all gear steps. This loss of horsepower was equal to 11-18% of the input power (52 kW). The transmission efficiency of the driving power unit was 81.5-89.0%. The noise of the driving power unit was 50-57 dB at 800 rpm, 70-77 dB at 1600 rpm, and 76-83 dB at 2400 rpm. The axle load test verified that the input torque and axle revolutions were constant. The results of the forward-reverse clutch performance test revealed that hydraulic pressure and torque changes were stably maintained when moving forward or backward, and its operation met the hydraulic design standards. Conclusions: When comprehensively examined, these research results were similar to the main driving power transmission systems from USA and Japan in terms of performance. Based on these results, tractor prototypes are expected to be created and supplied to farmhouses after going through sufficient in-situ adaptability tests.

• Journal of Advanced Marine Engineering and Technology
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• v.41 no.4
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• pp.330-336
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• 2017

This study performs a root cause analysis of the sticking that occurs in the hydraulically actuated wet type multi-disc friction clutch in a ship's diesel engine propulsion system that uses rubber elastic coupling. The fishbone method was used to study the sticking through dismantling investigation of the reduction gear and clutch, investigation of the components, and onboard system tests including nondestructive testing. The friction plate sticking is caused by the slip due to friction heat resulting from the leakage of control oil through cracks in the assembled hollow shaft. The friction plate cooling oil also leaks simultaneously through the crack, and partial sticking occurs due to the hot spots in the friction plates. These are caused by insufficient amount of cooling oil due to oil leakage.

• Proceedings of the KIEE Conference
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• 2002.06a
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• pp.187-190
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• 2002

In contrast to conventional electromagnetic motor, USM(Ultrasonic Motor), as piezoelectric ceramic applying ultrasonic mechanical vibration and as frictional-movement type motor, get rotational torque by elastic friction between stator and rotator, The USM, which is small motor without iron cores and coil as a simple structure, has little load weight, has character of high torque at low speed, and can apply a direct drive type without deceleration gear as low speed type. A response of USM from control input is satisfactory, and also generates much torque in low speed driving, and holding torque is much without supplying power. In this study, I designed and made Ultrasonic motor-digital multi controller(USM- DMC) using FPGA chip, A54SX72A made in Actel Corporation. By the minute, USM-DMC can control frequency, duty ratio, and phase difference of USM by llbit digital input from Pc. Therefore, when we use this controller, we can apply to typical parameter, frequency, phase difference, and voltage parameter, to control as well as we can do mixing control like phase-frequency, phase-voltage, frequency-voltage, frequency-phase-voltage, What is more, the strongest point is that it can trace frequency based on optimized frequency because we can input optimized resonant frequency while in motoring.

• Journal of Broadcast Engineering
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• v.27 no.6
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• pp.885-896
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• 2022

Motor failure in manufacturing plays an important role in future A/S and reliability. Motor failure is detected by measuring sound, current, and vibration. For the data used in this paper, the sound of the car's side mirror motor gear box was used. Motor sound consists of three classes. Sound data is input to the network model through a conversion process through MelSpectrogram. In this paper, various methods were applied, such as data augmentation to improve the performance of classifying fault motors and various methods according to class imbalance were applied resampling, reweighting adjustment, change of loss function and representation learning and classification into two stages. In addition, the curriculum learning method and self-space learning method were compared through a total of five network models such as Bidirectional LSTM Attention, Convolutional Recurrent Neural Network, Multi-Head Attention, Bidirectional Temporal Convolution Network, and Convolution Neural Network, and the optimal configuration was found for motor sound classification.

• Journal of the Korean Society of Safety
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• v.22 no.5
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• pp.1-6
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• 2007

Vibro-impacts in manual transmissions result due to several nonlinearities such as multi-staged clutch characteristics and gear backlashes. For the sake of understanding the torsional system, one specific manual transmission with front engine and front wheel drive configuration is investigated with a linear model under the several assumptions substituting the nonlinear factors. First, this system is examined with the mathematical approaches by expressing the governing equations to find out the torsional motions. Second, this system is analyzed using the linear model in order to understand its modal and frequency response characteristics using eigensolution method and the FRF(Frequency Responses Function) analysis. Third, with the given results from the eigensolutions, several mode shapes are investigated related to the torsional motion characteristics. Fourth, the system characteristics with the FRFs are studied with the basic approach, with which the several key parameters will be suggested based upon the results in the further studies.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2006.05a
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• pp.399-402
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• 2006

The outer race of CV(constant velocity) joint is an important load-supporting automotive part, which transmits torque between the transmission gear box and driving wheel. The outer race is difficult to forge because its shape is very complicated and the required dimensional tolerances are very small. Traditional warm and cold forging methods have their own limitations to produce such a complex shaped part; warm forging requires complex system with relatively higher manufacturing cost, while cold forging is not applicable to materials with limited formability. Therefore, multistage forging may be advantageous to produce complex shaped parts. In order to build a multistage forging system, it is necessary to characterize mechanical properties in response to system design parameters such as temperature, forging speed and reduction. For the analysis of formability of multistage forging process, finite element method(FEM) has been used for the process analysis. As a model case, a constant velocity (CV) joint forging process is analyzed by FEM, since CV joint has a complex shape and also its required dimensional tolerances are very tight. The data acquired by FEM is compared with operational forging data obtained from an industrial production line. Based on this comparative analysis, multistage forging process for CV joints is proposed.

• CDE review
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• v.4 no.3
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• pp.26-31
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• 1998

Recent trend of popularity of CAE(Computer Aided Engineering) tools and its availability, partly contributed by significant price reduction of H/W and SW, makes us believe CAE has already established terra firma as de jure tools, enablint the design improvement in the manufacturing am. However, if your jobs are required to be working closely with engineers located in the front line of manufacturing site, CAE is observed far from popularity, still being regarded as exclusive tools for engineers holding advanced degrees. Conventional methodologies depending on knowledge that was accumulated thorough trial and errors, depending primarily on engineering tables and formulas or proprietary know-how, are preferred as the de factor standard under the roof of contemporary development shops. Samsung camera, having stared its business since early 、80, has accumulated enough technological strength to compete in the world market. As today's consumers demand more sophisticated featured-lighter weight, built-in multi zoom and miniature size fitting in the palm-from camera manufacturer, so should Samsung camera respond to ever-delicate consumer's needs with great flexibility. Consequently conventional designers, without sophisticated analytical tools, with encounter solving the critical design factors that have never been treated as seriousness-marginal safety factors induced by reduced size of parts. In the study, CAE results of boss and gears were demonstrated as examples, which confirms the facts that the simple analysis done by front line designers, can bring distinguishable effects on the potential improvements of design and on the consequential influences on the future design process-simulation before actual tooling and productions.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2005.06a
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• pp.149-153
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• 2005

Marine Propulsion shafting system coupled with medium diesel engine forms multi-degree torsional vibration system which consist of many inertia masses such as crank, flywheel, propeller and sometimes gear system is adopted additionally for the purpose of improving propeller's propulsion efficiency or connecting with PTO/PTI. The periodic excitation torques generated by combustion pressure in cylinder and reciprocating masses induce various kinds of vibrations in this shafting system. If the frequency of this excitation torques is equal to the natural frequency of the shafting, the amplitude of the torsional vibration increases steeply and the damage of crankshaft or gears may be occurred by that. This frequency is called critical speed. When making a plan for shafting system, it is important for this frequency to be expected exactly and not to be in commonly used speed. For this reason, this paper introduces the experimental equipment for torsional vibration of marine propulsion shafting system and describes the theoretic and the experimental methods to look for natural frequencies.