• Proceedings of the KSME Conference
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• 2003.04a
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• pp.1730-1735
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• 2003

The plume-induced shock wave is a complex phenomenon, consisting of plume-induced boundary layer separation, separated shear layer, multiple shock waves, and their interactions. The knowledge base of plume interference effect on powered missiles and flight vehicles is not yet adequate to get an overall insight of the flow physics. Computational studies are performed to better understand the flow physics of the plume-induced shock and separation particularly at high plume to exit pressure ratio. Test model configurations are a simplified missile model and two rounded and porous afterbodies to simulate moderately and highly underexpanded exhaust plumes at the transonic/supersonic speeds. The result shows that the rounded afterbody and porous wall attached at the missile base can alleviate the plume-induced shock wave phenomenon, and improve the control of the missile body.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.752-757
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• 2003

The steady stress, modal analysis for the damaged blade was carried out to evaluate the integrity of LP 4 blade row. As a result, 4 dangerous modes for LP blade row were found in the interference diagram and it was confirmed that the nozzle passing frequency has nothing to do with the blade failure. And then the dynamic stress are analysed for the 4 dangerous modes. There are some points far out of maximum allowable stress in the cover and tenon. Therefore the blade is not safe according to the Goodman judgement. So the manufacturer have modified the design of cover and tenon. Until now, the power plant is being operated without special problems.

• Journal of the Korean Society for Precision Engineering
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• v.12 no.5
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• pp.46-56
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• 1995

As demands on the precision bevel gears are increased in the related industry, the exact kinematical investigations of a pair of spherical involute bevel gears are required for the computer aided design. The exact angular velocity ratio based on the characteristics of the spherical involute tooth is derived and verified from the relationship between rotational angles. Elementary kinematics of the gearsets is investigated by applying the transformation of the coordinate systems. The tooth contact lines based on logarithmic tooth-wise curve are examines in three dimentional space. Contact ratio is formulated and simulated according to the system parameters such as shaft angles, pressure angle, and spiral angles. The condition of teeth interference is dervied and the critical numbers of gear teeth are calculated. The whole surface geometry of a spiral bevel gearsets are discretized and visualized by a computer graphic tool.

• Transactions of Materials Processing
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• v.18 no.1
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• pp.80-86
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• 2009

This paper presents the plastic inhomogeneous deformation behavior of bimetal composite rods during the axisymmetric and steady-state extrusion process through a conical die. The rigid-plastic FE model considering frictional contact problem was used to analyze the co-extrusion process with material combinations of Cu/Al. Different cases of initial geometry shape for composite material were simulated under different conditions of co-extrusion process, which includes the interference and frictional conditions. From the simulation results, the sleeve cladding rate at the core/sleeve interface was recorded as a distribution of diameter ratio and interference conditions, which will be useful for the investigations of the bonding process during co-extrusion process. In addition, the results of the co-extrusion, connected with the results of the variations of diameter rate and average contact pressure, demonstrate a good agreement and present the possibility of describing the parameters of the plastic zones in non-uniform deformation of these type of composite materials.

• 한국전산유체공학회:학술대회논문집
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• 2003.08a
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• pp.120-125
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• 2003

Recently, lateral jet has been adopted as an effective control device for high maneuverable tactical missiles in supersonic regime. Aerodynamic interference caused by the lateral jet can be categorized into two phenomena : local interaction redistributing surface pressure near the jet exit region and downstream interaction affecting tail control effectiveness. As part of on-going research, this paper deals with the aerodynamic modeling to predict the variation of force and moment when lateral jet of is activated on the missile body. For this purpose, a series of numerical simulation has been performed and the results are presented. Using the information obtained by CFD, aerodynamic model of preliminary level has been constructed and is reviewed. Some relevant comparison with wind tunnel tests are presented.

• 연구논문집
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• s.24
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• pp.175-188
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• 1994

Water seal is composed of metal case, garter spring, and NBR. Axisymmetric, large deformation non-linear contact problems were solved by using the finite element method for the evaluation of performance of the water seal. Effects of the interference between seal and shaft, and the garter spring on the seal characteristics were considered in this analysis. The contact force and sealing performance increased as the interference and spring stiffness increases. And middle seal is main role sealing performance. Further research efforts are required to consider the effects of the garter spring stiffness, the eccentricity by the shaft or case, and the water pressure.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.1
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• pp.129-135
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• 2003

Optical fiber has many advantages, such as high reliability, long lifetime, immunity to the electromagnetic interference, high speed response and low cost. In this study, we proposed and developed an optical fiber impact and pressure sensor for prevention of accident which occurs in the automatic system or auto door. The principle of the sensor is to detect different optical intensity caused by variation of a speckle pattern due to the external perturbation. Speckle pattern appears at the end of a multimode fiber in which coherent beam propagates. The fabricated sensor in this study was tested. As a result of experiments, amplitude of the output signal isn't linear, but it has sufficient sensitivity for a sensor. Moreover, we can control sensitivity of the sensor by an amplifier at receiver. It has several advantages which are ability of detection at all point on the multimode fiber, large sensitive area, and many application areas for a sensing impact and pressure.

• International Journal of Automotive Technology
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• v.7 no.7
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• pp.847-852
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• 2006

A fitting process carried out in the automobile transmission assembly line is classified into three classes; heat fitting, press fitting, and their combined fitting. Heat fitting is a method that applies heat in the outer diameter of a gear to a suitable range under the tempering temperature and assembles the gear and the shaft made larger than the inner radius of the gear. Its stress depends on the yield strength of a gear. Press fitting is a method that generally squeezes gear toward that of a shaft at room temperature by a press. Another method heats warmly gear and safely squeezes it toward that of a shaft. A warm shrink fitting process for an automobile transmission part is now gradually increased, but the parts (shaft/gear) assembled by the process produced dimensional change in both outer diameter and profile of the gear so that it may cause noise and vibration between gears. In order to solve these problems, we need an analysis of a warm shrink fitting process in which design parameters such as contact pressure according to fitting interference between outer diameter of a shaft and inner diameter of a gear, fitting temperature, and profile tolerance of gear are involved. In this study, an closed form equation to predict the contact pressure and fitting load was proposed in order to develop an optimization technique of a warm shrink fitting process and verified its reliability through the experimental results measured in the field and FEM, thermal-structural coupled field analysis. Actual loads measured in the field have a good agreement with the results obtained from theoretical and finite element analysis and also the expanded amounts of the outer diameters of the gears have a good agreement with the results.

• Journal of the Korean Society for Precision Engineering
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• v.23 no.9 s.186
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• pp.54-60
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• 2006

Fitting process carried out in automobile transmission assembly line is classified into three classes; heat fitting, press fitting, and their combined fitting. Heat fitting is a method that heats gear to a suitable range under the tempering temperature and squeezes it toward the outer diameter of shaft. Its stress depends on the yield strength of gear. Press fitting is a method that generally squeezes gear toward that of shaft at room temperature by press. Another method heats warmly gear and safely squeezes it toward that of shaft. Warm shrink fitting process for automobile transmission part is now gradually increased, but the parts (shaft/gear) assembled by this process produced dimensional changes of gear profile in both radial and circumferential directions. So that it may cause noise and vibration between gears. In order to solve these problems, we need an analysis of warm shrink fitting process, in which design parameters are involved; contact pressure according to fitting interference between outer diameter of shaft and inner diameter of gear, fitting temperature, and profile tolerance of gear. In this study, an closed form equation to predict contact pressure and fitting load was proposed in order to develop optimization technique of warm shrink fitting process and verified its reliability through the experimental results measured in the field and FEM, that is, thermal-structural coupled field analysis. Actual loads measured in the field have a good agreement with the results obtained by theoretical and finite element analysis and also the expanded amounts of the gear profile in both radial and circumferential directions are within the limit tolerances used in the field.

• Journal of the Korean Society for Precision Engineering
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• v.23 no.5 s.182
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• pp.37-43
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• 2006

Fitting process carried out in automobile transmission assembly line is classified into three classes; heat fitting, press fitting, and their combined fitting. Heat fitting is a method that heats gear to a suitable range under the tempering temperature and squeezes it toward the outer diameter of shaft. Its stress depends on the yield strength of gear. Press fitting is a method that generally squeezes gear toward that of shaft at room temperature by press. Another method heats warmly gear and safely squeezes it toward that of shaft. Warm shrink fitting process for automobile transmission part is now gradually increased, but the parts (shaft/gear) assembled by this process produced dimensional change in both outer diameter and profile of the gear. So that it may cause noise and vibration between gears. In order to solve these problems, we need an analysis of warm shrink fitting process, in which design parameters are involved; contact pressure according to fitting interference between outer diameter of shaft and inner diameter of gear, fitting temperature, and profile tolerance of gear. In this study, an closed form equation to predict contact pressure and fitting load was proposed in order to develop optimization technique of warm shrink fitting process and verified its reliability through the experimental results measured in the field and FEM, that is, thermal-structural coupled field analysis. Actual loads measured in the field have a good agreement with the results obtained by theoretical and finite element analysis and also the expanded amounts of the outer diameters of the gears have a good agreement with results.