• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.12
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• pp.2590-2597
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• 2002

A new torque measuring apparatus adopting the basic principle of a capacitive type sensor is proposed in this article. Two plate electrodes are working as a capacitive sensor, whose capacitance varies as torque is applied. One end of each plate is connected to the torque carrying shaft. Output characteristics of the torque sensor were theoretically analyzed and its validity was investigated through experiment. Calculations and calibration experiments show that the output is nonlinear, that is, the sensitivity is very high at low torque but decreases as torque increases. The sensitivity of the proposed system is about 100 times roughly higher than that of a conventional 4-strain gauge type torque sensor.

• Proceedings of the KSME Conference
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• 2000.11b
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• pp.757-763
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• 2000

In vehicle exhaust systems the sound attenuation and the reduction of flow losses are often two competing demands. The present study considers a fully vehicle exhaust system and investigates experimentally both the sound attenuation and the flow performance of production configurations including the catalyst, the resonator, and the muffler. Dynamometer experiments have been This study is on the development of a new muffler composed of a valve system using an elasticity of spring. The valve system conducted with the daewoo 1500cc Lanos engine with speeds ranging from 1000 to 5000 rpm. Measurements include the flow rates, the temperatures and the absolute dynamic pressures of the hot exhaust gases at point locations. The present study describes the experimental aspects of an ongoing effort to validate and use the nonlinear fluid dynamic models in the time-domain for the prediction of the acoustic and power performance of firing internal combustion engines with full production exhaust systems.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.485-490
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• 2003

In this paper, a nonlinear finite-element method was employed to analyze mechanical behaviors of the balloon-expandable stent. Beyond safety considerations, this type of analysis provides mechanical properties that are often difficult to obtain by experiments. Mechanical properties of the stent expansion pressure, radial recoil, longitudinal recoil and foreshortening were studied using commercial FEM code, ANSYS. As a result, the pressure necessary to expand the stent up to a diameter of 3mm was 7.6atm, longitudinal recoil, radial recoil and foreshortening were -0.388%, 2.87% and 4.07% respectively. In conclusion, a finite element model used in this study could help in designing new stents or analyzing actual stents.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.11a
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• pp.683-686
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• 2000

A new approach to the task of aligning a robot using camera is presented in this paper. We apply an elitist GA to find the joints angles of manipulator to reach target position instead of using nonlinear least error method. Since it employs parallel search and have good performance in solving optimization problems. In order to improve convergence speed, the floating coding method and geometry constraint conditions are used. Experiments are carried out to exhibit the effectiveness of vision-based control using elitist genetic algorithm.

• International Journal of Precision Engineering and Manufacturing
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• v.3 no.3
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• pp.82-89
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• 2002

The need of ultra-precision machine tools, which manufacture and machine the high precision parts used in computers, semi-conductors and other precision machines, has been increased over years. Therefore it is important to design the driving parts, which affect significantly on their performances. In this paper, the dynamic analyses on the belt-driven system were explored. Relation of the acoustical natural frequency and the tension of belt was derived and presented through experiments. Also, while the dynamic loads on motor system were changed, dynamic deflections were calculated through finite element analysis. Nonlinear characteristics of the bearings having an effect on the dynamic performance were studied and the belt connecting the motor (driving part) to spindle of a machine tool (driven part) was modeled as truss and beam elements fur simulations under various conditions, and a beam element model was verified to be more useful.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.8
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• pp.2039-2050
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• 1995

The nonlinear low-Reynolds-number k..epsilon. model of park and Sung is extended to predict the turbulent heat transports in separated and reattaching flows. The equations of the temperature variance( $k_{\theta}$ and its dissipation rate(.epsilon.$_{\theta}$ are solved, in concert with the equations of the turbulent kinetic energy(k) and its dissiation rate(.epsilon). In the present model, the near-wall effect and the non-equilibrium effect are fully taken into consideration. The validation of the model is then applied to the turbulent flow behind a backward-facing step and the flow over a blunt body. The predicted results of the present model are compared and evaluated with the relevant experiments.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.04a
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• pp.521-527
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• 1997

Irregular shapes and growth behavior of surface micro-crack showed very complex and nonlinear propeties and many investigators have performed theoretical analysesand experiments on them to characterize fatigue strength. They had difficulties in estimating fatigue life due to random distribution, growth and coalescence of surface micro-cracks. The straightness of crack growth along intergranular and transgranular was prevented from irregular microstructure and precipitates. Euclid geometry can't quantify shape of surface micro-crack but ftractal geometry can. Therefore, it is suggested that average fractal dimension of surface micro-cracks is able to estimate fatigue life but fractal dimension of maximum surface micro-crack is not in Al 2024-T3 alloy.

• Journal of KSNVE
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• v.6 no.6
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• pp.819-825
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• 1996

Nonlinear dynamic characteristics of rubbing phenomenon in rotor dynamics are investigated experimentally and numerically. Rubbing phenomenon occurs when rotor contacts with stator during whirling and causes the large amplitude of vibration, high whirl frequencies, and possibly catastrophic failure. Rubbing has various types of forward whirl, backward rolling, backward slipping, and partial rub depending on the system parameters of rotating machinery and running speed. Experiments are performed for forward whirl and backward whirl. And numerical analysis are conducted to explain the changes between backward rolling and backward slipping. Experimental and numerical results show that the types of whirling motion depends on the friction coefficient between rotor and stator and the eccentricity of rotor.

• Wind and Structures
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• v.6 no.5
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• pp.357-386
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• 2003

A number of methods based on various ideas have been proposed for simulating the non-Gaussian stationary process. However, these methods have some limitations. This paper reviewed several simulation methods based on the translation method using logarithmic and polynomial functions, which have emerged in the history of statistics and in the field of civil engineering. The applicability of each method is discussed from the viewpoint of the reproducibility of higher order statistics of the object function in the simulated sample functions, and examined using pressure signals measured from wind tunnel experiments for various shapes of buildings. The parameter estimation methods, i.e. the method of moments and quantile plot, are also reviewed, and the useful aspects of each method are discussed. Additionally, a simple worksheet for parameter estimation is derived based on the method of moment for practical application, and the accuracy is discussed comparing with a set of previously proposed formulae.

• 제어로봇시스템학회:학술대회논문집
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• 1995.10a
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• pp.460-463
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• 1995

The present paper studies a robot manipulator's contact tasks on the uncertain flexible objects. The flexible object's distributed parameter model is approximated into a lumped "position state-varying" model. By using the well-known nonlinear feedback compensation, the robot's control space is decomposed into the position control subspace and the object's torque control subspace. The optimal state feedback is designed for the position loop, and the robot's contact force is controlled through controlling the resultant torque on the object using model-reference simple adaptive control. Experiments of a PUMA robot interacting with an aluminum plate show the effectiveness of this control approach. approach.