• Journal of rehabilitation welfare engineering & assistive technology
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• v.7 no.2
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• pp.101-107
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• 2013

In this paper, we were to investigate effect of correction to muscle imbalance in lower limbs according to reduction of weight bearing methods of four point of horizontal shaft using two-belt treadmill. Participants were divided to two group according to each ten peoples who have difference of muscle function in left and right legs over 20%. Experiment progressed forty minutes a day three days a week, total four weeks and we estimated the maximal peak torque and average power for testing joint torque in hip, knee and ankle. The results showed that the correction effect of muscle imbalance to the maximal muscle strength was the most effective in hip joint. Also in knee joint, correction effect of muscular reaction was the most effective too. We thought that reduction of weight bearing methods could be positive effect to correct muscle imbalance in lower limbs.

• Transactions of the Korean Society of Automotive Engineers
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• v.21 no.6
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• pp.201-208
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• 2013

Recently, there has been an active study about weight reduction for automotive. This study is prediction and evaluation of one pice type steering component, which is universial joint. Steering system is a core of major safe device in vehicle. Universial shaft adopted in steering system transmit steering torque between olumn and steering gear. Conventional universial shaft is produced by welding process because of geometric complexity. But welding process has some weakness such as deflection on surface, residual stress, and deteronration of material properties so it can deteriorate durability of vehicle.

• Journal of the Korean Society for Precision Engineering
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• v.33 no.4
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• pp.287-293
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• 2016

A monobloc tubular drive shaft is designed to obtain the improved structural safety and the weight reduction of the drive shaft together. The monobloc tubular drive shaft can be manufactured from an incremental hot rotary forging process. The aim of this study was to experimentally determine conditions of an incremental hot rotary forging process for a monobloc tubular drive shaft. Induction heating experiments were performed to estimate a proper heating time of an initial workpiece in an induction heating process. Several incremental hot rotary forging experiments were carried out using a mechanical press with the designed set-up. The step distance and the step angle were chosen as controllable forming parameters. Based on the results of the experiments, the influence of forming parameters on the quality of the forged part was investigated. Finally, a forming map and a proper forming condition of the incremental hot rotary forging process were estimated.

• Journal of Bio-Environment Control
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• v.4 no.2
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• pp.232-239
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• 1995

This study was carried out to get required torque data needed to design and develop a roll-up ventilation system in a pipe-constructed plastic film green-house. The results obtained from this study are as follows : 1. The required torques of a roll-up ventilation system in greenhouse are the functions of its length. The torques should multiplied by the conversion coefficients (2.0 in ceiling vent, 1.8 in side vent) in case of application. 2. In constructing pipe-constructed plastic film greenhouse, a shaft pipe is the largest essential element in roll - up shaft weight constitution which have an effect on the required torques. Therefore, the pipe should be light using nonferrous materials like aluminum alloy. 3. A planetary reduction ventilator of differential ring gear type is suitable for a roll-up ventilation system, because it can make high efficient reduction just using the first step shift.

• Journal of Veterinary Clinics
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• v.34 no.3
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• pp.200-203
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• 2017

The objective of this study was to evaluate the effectiveness of the minimally invasive plate osteosynthesis (MIPO) method for treatment of tibial shaft fractures in dogs by comparing MIPO radiographic and fracture healing time results with those from the popular open reduction and internal fixation (ORIF) technique. In this clinical study at the Royal Animal Medical Center, five consecutive dogs with diagnoses of comminuted tibial shaft fractures were treated with the MIPO surgical approach. For comparison, an additional five breed-, age-, and weight-matched dogs with comminuted tibial shaft fractures were treated with the ORIF technique. Mean healing time was $75.6{\pm}12.5$ days in the MIPO group and $131.8{\pm}18.6$ days in the ORIF group (p < 0.01). The mean surgery time in the MIPO group ($36.4{\pm}3.5$ minutes) was significantly shorter (p < 0.01) than that for the ORIF group ($47.0{\pm}2.2$ minutes). Based on the short surgical and healing times, the MIPO approach is clinically superior to the ORIF approach and should be the preferred approach in tibial fracture cases.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2006.05a
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• pp.153-158
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• 2006

Nowadays, hollow upper-shaft of monobloc type has been considered for weight reduction and high quality in the automobile industry. To form the upper-shaft under tube cold extrusion, Taguchi method is applied to optimize the die design in this study. Taguchi method for optimum die design is to establish the optimal combination of design parameters and to reduce a number of experiments. Effect of parameters including the die relief, mandrel, die half angle is investigated and analyzed based on FEA analysis using a FEM commercial software MSC_Marc. Furthermore extrusion experiments have been performed to verify the results investigated in the FEM simulations.

• Korean Journal of Agricultural Science
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• v.45 no.2
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• pp.283-289
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• 2018

Agricultural gear reducers are used in a variety of agricultural machinery designs such as in agricultural tractors and transport cars, and even greenhouses. For greenhouses, a gear reducer is used to control windows on the side and the roof. Gear reducers for agricultural applications are designed using the empirical method because of the lack of a standard for experimentation. Simulation is necessary for the optimal design of an agricultural gear reducer. There are many advantages to this optimization such as low-cost maintenance, reduced size, and weight. In this study, bending and contact safety factor simulation for the gear reducer of a greenhouse was conducted by decreasing the face widths of helical gear shaft 2 and shaft 3 from 30.8 and 30 mm, respectively, at an interval of 4 mm. The bending and contact safety factors were calculated using AGMA standard. Simulation results showed that bending and contact safety factors decreased rapidly when the face width of the helical gear on shaft 2 was 30 mm and the face width of helical gear on shaft 3 decreased from 30.8 mm to 26.8 mm, suggesting that it would be safe to reduce the face width of the helical gear on shaft 3 to 26.8 mm. The reduction of the face width also reduced the weight of the agricultural gear. This study suggests that the agricultural gear reducer safety factor decreases as the face width decreases.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.13 no.1
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• pp.107-114
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• 2014

A friction hinge system which moves without power was designed and developed using the principle of friction force, which is caused by interference between the inner diameter of a silicon cap and the outer diameter of a cylindrical roller bearing with one-way rotation in a counterclockwise direction. The system was applied to the lid of buffet ware, which moved up by external force and moved down by gravitational force. However, design conditions which included a rotation angle of the hinge of more than 80 degrees and a closing time of more than 20 seconds were required when the lid of the buffet ware closed due to gravitational force. The design safety of the friction hinge body connected to the lid of the buffet ware from the hinge system was checked on the basis of structural, fatigue and thermal analyses. The material of the shaft, cap and flange among the hinge elements was changed to polyethylene from steel to reduce the weight of the friction hinge system. An injection molding simulation was performed and injection molds of the shaft, cap and flange were created. The weight of the hinge system was decreased from 805g to 219g.

• Journal of the Korean Society of Propulsion Engineers
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• v.5 no.4
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• pp.31-39
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• 2001

Composite propeller shafts for a vehicle have major advantages such as reduction of vibration, noise, and weight. A propeller shaft was designed with a carbon/epoxy composite material using the finite element method(FEM), and prototype shafts for tests were manufactured by the filament winding manufacturing process. In order to verify the design procedure by FEM, Two kinds of experimental tests were carried out using a FFT analyzer with impact hammers and a critical speed measuring apparatus for measurement of natural frequencies and critical speeds. The difference between the FEM analysis result and the test result was less than 3.4%, showing FEM analysis results to be acceptable. The parametric study was focused on determining the factor affecting the vibration and strength characteristics of the propeller shaft based on FEM. In investigation of the change in natural frequency without an increase in propeller shaft weight, it was found that the winding angle is the most significant factor affecting the vibration and strength characteristics.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.48 no.12
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• pp.953-960
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• 2020

This paper presents an optimization of gear web design used in a main gear train of an engine reduction gearbox for a rotorcraft. The optimization involves the minimization of a total weight, transmission error, misalignment, and face load distribution factor. In particular, three design variables such as a gear web thickness, location of rim-web connection, and location of shaft-web connection were set as design parameters. In the optimization process, web, rim and shaft of gears were converted from the 3D CAD geometry model to the finite element model, and then provided as input to the gear simulation program, MASTA. Lastly, NSGA-II optimization method was used to find the best combination of design parameters. As a result of the optimization, the total weight, transmission error, misalignment, face load distribution factor were all reduced, and the maximum stress was also shown to be a safe level, confirming that the overall gear performance was improved.