• Journal of the Korean Society of Manufacturing Process Engineers
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• v.18 no.10
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• pp.54-59
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• 2019

The final reduction drive in tactical vehicles has a wear-pad that helps to maintain adequate end floating when the hub assay operates. The input axis and sun gear move repeatedly with the axis when tactical vehicle is operating. The hub assay is designed so that the wear pads won't seize during operation. Seizure of the wear pads during operation results in oil leakage. In our study, the fault mechanism was analyzed to prevent the seizure of the wear pads and an optimal design for the shape and material of the wear-pad was explored. We then observed the changes in temperature, shape, and material of several important parts.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.56 no.3
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• pp.341-346
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• 2023

This study aimed to suggest an alternative income generation (AIG) for local artisanal fisheries communities in the southern coastal area of Bangladesh, which is vulnerable to climate change. To analyze the problems of local artisanal fisheries caused by climate change, field surveys and in-depth interviews with fishermen and government officials were conducted. Livelihood risk factor (LRF) in the marine fishing sector included reduction of fishing days and fish production and damage to fishing vessels and fishing gear due to cyclone and sea-level rise. LRF in the aquaculture sector included cultured fish escape, reduction of aquaculture production, and water pollution due to Monsoon flood. A common challenge for two sectors was high interest rate on commercial loans. Small-scale tank aquaculture is recommended as AIG for securing income of artisanal fisheries communities. In the early stages of dissemination of small-scale tank aquaculture technology, it is necessary to prevent fishermen from struggling to repay high-interest rate loans through technology transfer and facility support by official development assistance. The aquaculture training center, along with the technical education, will also contribute toward expansion of local distribution network and marketing support to establish a value chain for local artisanal fisheries communities.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.41 no.12
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• pp.987-993
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• 2013

Korean Utility Helicopter(KUH) is the first korean-developed helicopter. Its first flight was performed in March 2010 and then its development was completed successfully by June 2012. During flight test phase, KUH faced various vibration problems and appropriate vibration-reduction devices were designed and applied to solve the problems. The vibration-reduction devices were applied to main rotor blades, main gear box(MGB) supporting structure, cockpit, cabin and pilot seats to reduce rotor-induced 4/rev vibration. Also, dome-fairing was introduced in order to reduce the tail-shake vibration. This paper shows design technique and flight test results for vibration-reduction devices that have been incorporated into KUH.

• Journal of the Institute of Electronics and Information Engineers
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• v.54 no.6
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• pp.117-122
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• 2017

Cabin noise due to the electric powertrain of electrical vehicle may consists of motor noise caused by electrical mismatch and gear noise coming from reduction gearbox. These sound may be considered rather small noise compared to those of internal combustion engine, but without masking effect, the noise can be more annoying for customer. Thus, this paper demonstrates the characteristics of electrical vehicle powertrain noise, and the effect of passive damping material for the noise reduction. The typical motor noise can be affected by the motor torque. Also, it is demonstrated that the reduction gearbox may be a weak point for the noise path compared to the motor housing. With vehicle test, it is shown that the damping patch is more effective for noise reduction with deceleration condition than with acceleration condition.

• Transactions of the Korean Society of Automotive Engineers
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• v.19 no.1
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• pp.17-24
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• 2011

TMED(Transmission Mounted Electric Device) parallel hybrid configuration can realize EV(Electric Vehicle) mode by disengaging the clutch between an engine and a transmission-mounted motor to improve efficiencies of low load driving and regenerative braking. In the EV mode, however, jerk can be induced since there are insufficient damping elements in the drive-train. Though the jerk gives demoralizing influence upon driving comport, adding a physical damper is not applicable due to constraints of the layout. This study suggests the jerk reduction control, composed of active damping method and torque profiling method, to suppress the jerk without hardware modification. The former method creates a virtual damper by generating absorbing torque in the opposite direction of the oscillation. The latter method reduces impulse on the mated gear teeth of the drive-train by limiting the gradient of traction torque when the direction of the torque is reversed. To validate the effectiveness of the suggested strategy, a series of vehicle tests are carried out and it is observed that the amplitude of the oscillation can be reduced by up to 83%.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.21 no.11
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• pp.1074-1083
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• 2011

Noise of digital camera has been noticeable to its users. Particularly, noise of a barrel assembly module in zoom in/zoom out operation is recorded while taking a video. Reduction of barrel noise becomes crucial but there are not many studies on noise of digital camera due to its short history of use. In this study, experiment-based analyses are implemented to identify sources of noise and vibration because of complexity and compactness of the barrel system. Output noise is acquired in various operation conditions using synchronization for spectral analysis. Noise sources of a barrel assembly in zoom operating are first identified by the comparison with gear frequency analysis and then correlation analysis between noise and vibration is applied to confirm the generation path of noise. Analysis on noise transfer characteristic of zoom module is also carried out in order to identify the most contributing components. One of possible countermeasures of noise in zoom operating is investigated by an experimental approach.

• Journal of the Korean Institute of Intelligent Systems
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• v.17 no.1
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• pp.19-25
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• 2007

Among the precision reduction gent drivers lot robot system, the cycloid reducer is well known for it's high performances. Designing this reducer, there are many factors which must be considered. First, a geometrical analysis of tooth shape must be drawn from the basic concept. Second, loads, stresses and modification factors on tooth should be calculated exactly. Finally, a computer software to optimize the design of cycloid tooth needs developing on the basis of the geometric and force equations. In this research, the expert system to design the cycloid reducer was developed using Visual C++ so, the most important factors can be obtained automatically as the user put the simple input data.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.23 no.3
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• pp.234-239
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• 2013

There are many types of speed reducer for industrial uses. However the cycloid speed reducer is widely used in manipulators based on excellent performance of low backlash, high reduction ratio and compact size. It is essential to use precision speed reducer for accuracy of position controls on robot systems and electric vehicles. The cycloid speed reducer has a eccentric rotating motion and offset to avoid some problem of assembly, so it has a disadvantage for vibration. In this paper, a multi-body dynamic model is developed for a cycloid speed reducer and the dynamic behaviors of the reducer are investigated. The cycloid speed reducer consists of cycloidal plate gears, housing gear, input shaft, output pin and shaft, and eccentric bearings. Using a CAD program, each component of cycloid reducer is modeled based on the offset and eccentric. Multi-body simulations using Recurdyn and test using a rig tester are performed. As a result, the pin reaction force and the amplitude of housing displacement are increased by the larger offset and smaller eccentric value of cycloid reducer.

• Journal of Biosystems Engineering
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• v.25 no.4
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• pp.257-264
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• 2000

A tractor attached TMR(model 430) mixer has been developed in a previous study. However, the mixer was found to be improved through field applications in its capacity, manufacturing cost, ergonomic design and power-train requirement. The TMR mixer was modified into a model TMR500, approved by Institute of Agricultural Mechanization, as follows : 1. Roughage cutting system was seperated from the mixer, resulting in the 33% reduction of manufacturing cost. 2. Enlarged hopper capacity enabled to feed 60 heads at a batch. 3. Hydraulically controlled gate system saved ergonomic man power. 4. Power transmission system was changed from a chain-sprocket system(27:1) to the gear-train reduction system(38.6:1) to satisfy the recommended use of 540rpm PTO input.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2007.05a
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• pp.434-437
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• 2007

Cold forging technology of a gear product is being interested in the dimensional accuracy, high stiffness and reduction of stress concentration. Especially it is needed to avoid the damage due to extremely high local pressure. Therefore it is important to ensure high pressure in die design. In this study, single die insert type and splitted die insert type are considered to recognize the notch effects in the die of sprocket forming. The stress concentration has been released at the notch area by the cushion effect in the splitted die insert.