• Journal of the Computational Structural Engineering Institute of Korea
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• v.28 no.3
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• pp.283-291
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• 2015

In this paper, the two-dimensional(2D) and three-dimensional(3D) analyses have been performed in order to evaluate the structural integrities and compare 2D and 3D results for nozzles attached to cylindrical shells. Three nozzles, which are currently used in the nuclear power plant, are chosen to evaluate the structural integrities, and each nozzle is subjected to internal pressure, temperature variation and external loads. It is found that the 2D analysis for internal pressure should be performed with a factor of more than 1.5 or a stress concentration factor; 2D and 3D analysis results for temperature variation are almost similar to each other regardless of cladding; and the analysis results for external loads by WRC Bulletin 297 are more conservative than the 3D analysis results.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.4
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• pp.437-442
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• 2014

The equipment or with a constant torque and a variable stress due to axial vibration such as the turbine-generator system in nuclear power plant show the fatigue fracture behavior. Thus this study whoul aim to measure the torsional stress and analyze the fatigue fracture behavior. To achieve this, we manufactured the equipment similar with turbine-generator system and applied various torsional vibration stress due to external load. In particular, the evaluation was conducted with the existing evaluation methods of the fatigue behavior of known stress-life, strain-life, crack growth assessment methods. With increasing the external load and independent methods tends to decrease the fatigue life was confirmed up to 10 times in 5 kV external load compared to without external load.

• Journal of Aerospace System Engineering
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• v.16 no.1
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• pp.97-103
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• 2022

An aircraft component can only be mounted on an aircraft if it has been certified to have a structural robustness under flight load conditions. Among the major components of the aircraft, a pylon is a structure that connects external equipment such as an engine, and external attachments with the main wing of an aircraft and transmits the loads acting on it to the main structure of the aircraft. In civil aircraft, when there is an incident of fire in the engine area, the pylon prevents the fire from spreading to the wings. This study presents the results of structural static tests performed to verify the structural robustness of a fuel pylon used to mount external fuel tank in an aircraft. In the main text, we present the test set-up diagram consisting of test fixture, hydraulic pressure unit, load control system, and data acquisition equipment used in the structure static test of the fuel pylon. In addition, we introduce the software that controls the load actuator, and provide a test profile for each test load condition. As a result of the structural static test, it was found that the load actuator was properly controlled within the allowable error range in each test, and the reliability of the numerical analysis was verified by comparing the numerical analysis results and the strain obtained from the structural test at the main positions of the test specimen. In conclusion, it was proved that the fuel pylon covered in this study has sufficient structural strength for the required load conditions through structural static tests.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.5
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• pp.605-611
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• 2019

The fuel sloshing due to the rapid manoeuvre of the aircraft causes significant loads on internal components, which may break components or piping. In particular, a significant load is applied to the joint of the external fuel tank by sloshing movement, which may affect the safety of the aircraft when the joint of the external fuel tank is damaged. Therefore, in order to improve the survivability of aircraft and crew members, the design of external fuel tanks, and joints should be performed after evaluating the sloshing load through a numerical analysis of the fuel sloshing conditions. In this paper, a numerical analysis was performed on the sloshing test of the external fuel tank for rotorcraft. ALE (Arbitrary Lagrangian Eulerian) technique was used, and the test conditions specified in the U.S. Military Specification (MIL-DTL-27422D) was applied as the conditions for numerical analysis. As a result of the numerical analysis, the load on the joint of the external fuel tank was calculated. Moreover, the effects of sloshing movement on structural soundness were assessed through analysis of stress levels and margin of safety on metal fittings and composite containers.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.76-81
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• 2004

Problems with the control, oscillatory motion and compliance of pneumatic systems have prevented their widespread use in advanced robotics. However, their compactness, power/weight ratio, ease of maintenance and inherent safety are factors that could be potentially exploited in sophisticated dexterous manipulator designs. These advantages have led to the development of novel actuators such as the McKibben Muscle, Rubber Actuator and Pneumatic Artificial Muscle Manipulators. However, some limitations still exist, such as a deterioration of the performance of transient response due to the changes in the external inertia load in the pneumatic artificial muscle manipulator. To overcome this problem, a switching algorithm of the control parameter using a learning vector quantization neural network (LVQNN) is newly proposed. This estimates the external inertia load of the pneumatic artificial muscle manipulator. The effectiveness of the proposed control algorithm is demonstrated through experiments with different external inertia loads.

• Journal of Mechanical Science and Technology
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• v.18 no.8
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• pp.1388-1400
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• 2004

Problems with the control, oscillatory motion and compliance of pneumatic systems have prevented their widespread use in advanced robotics. However, their compactness, power/weight ratio, ease of maintenance and inherent safety are factors that could be potentially exploited in sophisticated dexterous manipulator designs. These advantages have led to the development of novel actuators such as the McKibben Muscle, Rubber Actuator and Pneumatic Artificial Muscle Manipulators. However, some limitations still exist, such as a deterioration of the performance of transient response due to the changes in the external inertia load in the pneumatic artificial muscle manipulator. To overcome this problem, a switching algorithm of the control parameter using a learning vector quantization neural network (LVQNN) is newly proposed. This estimates the external inertia load of the pneumatic artificial muscle manipulator. The effectiveness of the proposed control algorithm is demonstrated through experiments with different external inertia loads.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.49 no.2
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• pp.85-92
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• 2000

30 kVA rotating-field type Super-Conducting Generator is built and tested with intensive FE(Finite Element) analysis. The generator is driven by VVVF inverter-fed induction motor. Open Circuit Characteristic(OCC) and Short Circuit Characteristic(SCC) are presented in this paper. Also, the test result under the light load(up to 3.6 kW) are given. From the design stage, 2-D FE analysis coupled with the external circuit has been performed. The external circuit includes the end winding resistance and reactance as well as two dampers. When compared with the test data, the FE analysis results show a very good agreement.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 1996.06c
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• pp.369-378
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• 1996

A Lugged steel wheel was operated with two kinds of travel reduction on a sandy clay. " Small -sized transucers of the three-surfaced lug type " were installed to the wheel for the measurement of normal and tangential forces acting on a trailing lug side, lug face and a leading lug side separately . The external results acting on each surface were calculated from those measured forces. This results proved qualitatively that the relationships between external forces and lug surfaces obtained from mathematical analyses were external forces and lug surfaces obtained from mathematical analyses were correct. The traction, the motion resistance and the dynamic load were changing at the three lug surface under various operating conditions . Therefore, total analyses of three surface were indispensable to discuss the performance of the wheel lug.

• Journal of Institute of Control, Robotics and Systems
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• v.11 no.2
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• pp.103-108
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• 2005

Loading/Unloading task in the real industry is performed by crane, but most of the loading/unloading task with the weight of 5kg∼30kg is done by human workers and this kind of work causes industrial disaster of workers. Therefore it is necessary to develop low cost loading/unloading manipulator system to prevent this kind of industrial accidents. This paper is concerned with the design and fabrication of 2 axis pneumatic manipulators using on/off solenoid valves and accurate position control without respect to the external load and low damping in the pneumatic rotary actuator. To overcome the change of external load, switching of control parameter using LVQNN (Learning Vector Quantization Neural Network) is newly applied, which estimates the external loads in the pneumatic cylinder. As an underlying controller, a state feedback controller using position, velocity and acceleration is applied to the switching control system. The effectiveness of the proposed control algorithms are demonstrated through experiments of pneumatic cylinder with various loads.

• Journal of the Korea institute for structural maintenance and inspection
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• v.9 no.3
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• pp.178-186
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• 2005

In this study, the PSC girder bridge retrofitted with external tendons is tested to verify the strengthening effects. We measure the variations of the displacement and strain at mid-span of each beam as external tendons are removed in sequence. The structural behavior of the bridge are examined using controlled truck load tests for the systems before and after all external tendons were removed. From the test results, the characteristics of structural behavior of the bridge do not change significantly, but the natural frequency is decreased after the external tendons are removed. The strengthening effects of bridges can be exactly estimated by analytical methods some extent. As a result of this study, when a PSC girder bridge is deteriorated, the bridge can be retrofitted effectively by External Prestressing Strengthening Method, and the strengthening effects can be predicted through accurate structural analysis.