• Proceedings of the KAIS Fall Conference
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• 2011.05b
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• pp.529-532
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• 2011

A theoretical model has been studied to describe the sound radiation analysis for structure vibration noise of vehicle tires under the action of random moving line forces. When a tire is analyzed, it had been modeled as curved beams with distributed springs and dash pots that represent the radial, tangential stiffness and damping of tire, respectively. The reaction due to fluid loading on the vibratory response of the curved beam is taken into account. The curved beam is assumed to occupy the plane y=0 and to be axially infinite. The expression for sound power is integrated numerically and the results examined as a function of Mach number, wave-number ratio and stiffness factor. The experimental investigation for structure vibration noise of vehicle tire under the action of random moving line forces has been made. Based on the Spatial Transformation of Sound Field techniques, the sound power and sound radiation are measured. Results strongly suggest that operation condition in the tire material properties and design factors of the tire govern the sound power and sound radiation characteristics.

• Journal of the Korean GEO-environmental Society
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• v.7 no.5
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• pp.67-77
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• 2006

Bearing capacity of soil can be improved by several conventional ground improvement techniques like stabilization and compaction. Recently, the necessity on the reseaches for the bearing capacity of footing reinforced by Geotextile is being significantly increased. In this paper, a series of model tests on sandy ground reinforced by a layer of Geotextile were performed under plane strain condition, and the effects of bearing capacity improvement and behaviour of sandy ground were observed through tests for position and horizontal length, material strength of reinforcement.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.11a
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• pp.358-361
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• 2000

To reduce the leadtime for a new model according to the strict market requirements, automobile manufacturer begins to utilize 3-dimensional CAD based techniques such as DMU(Digital Mock-Up). RP(Rapid Prototyping), VE(Virtual Engineering). But, not so many satisfactory utilities have been introduced to deal with the emotional properties such as embossment on the surface of interior parts and touch from material characteristics in virtual environment. It is required to manufacture prototype parts to verify actual feeling of the passengers in real automobile. This paper suggests a methodology to enhance emotional property via embedding embossment on the surface of prototype car interior trim without deterioration of dimensional accuracy using RIM(Reaction Injection Molding) and vacuum forming method.

• Journal of Power System Engineering
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• v.15 no.6
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• pp.5-10
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• 2011

A turbocharger is subjected to rapid temperature changes during thermal cyclic loads. In order to predict the thermo-mechanical failures, it's very important to estimate temperature distributions under the thermal shock test. This paper suggest the finite element techniques with the temperature histories, a constitutive material model and the mechanical constraints to calculate the thermal stresses and plastic strain distributions for the turbine housing. The first step was to develop a simple coupon approach to represent the failure mechanism of the classical design shapes and secondly applied the actual turbocharger to predict and validate the weak locations under the physical engine test.

• Smart Structures and Systems
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• v.22 no.2
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• pp.193-200
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• 2018

From the viewpoint of engineering applications, the prediction of the failure of bogies plays an important role in preventing the occurrence of fatigue. Fatigue is a complex phenomenon affected by many uncertainties (such as load, environment, geometrical and material properties, and so on). The key to predict fatigue damage accurately is how to quantify these uncertainties. A Bayesian model is used to account for the uncertainty of various sources when predicting fatigue damage of structural components. In spite of improvements in the design of fatigue-sensitive structures, periodic non-destructive inspections are required for components. With the help of modern nondestructive inspection techniques, the fatigue flaws can be detected for bogie structures, and fatigue reliability can be updated by using Bayesian theorem with inspection data. A practical fatigue analysis of welded bogies is utilized to testify the effectiveness of the proposed methods.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.1560-1565
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• 2003

Tapping mode atomic force microscopy (TM-AFM) utilizes the dynamic response of a resonating probe tip as it approaches and retracts from a sample to measure the topography and material properties of a nanostructure. We present recent results based on nonlinear dynamical systems theory, computational continuation techniques and detailed experiments that yield new perspectives and insight into AFM. A dynamic model including van der Waals and Derjaguin-Muller-Toporov (DMT) contact forces demonstrates that periodic solutions can be represented with respect to the approach distance and excitation frequency. Turning points on the surface lead to hysteretic amplitude jumps as the tip nears/retracts from the sample. Experiments are performed using a tapping mode tip on a graphite sample to verify the predictions.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.05a
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• pp.362-367
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• 2003

A new mechanical-electrical hybrid passive dam ping treatment is proposed to improve the performance of structural vibration control. The proposed hybrid passive damping system consists of a constrained layer damping treatment and a shunt circuit. In a passive mechanical constrained layer damping, a viscoelastic material damping layer is used to control the structural vibration modes in high frequency range. The passive electrical damping is designed for targeting the vibration amplitude in the low frequency range. The governing equations of motion are derived through the Hamilton's principle. The obtained mathematical model is validated experimentally. The presented theoretical and experimental techniques provide invaluable tools for controlling the multiple modes of a vibrating structure over a wide frequency band.

• Proceedings of the KIEE Conference
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• 2003.11a
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• pp.210-212
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• 2003

Conventional PDC relaying with 2nd harmonic restraint makes some doubt in reliability. It can contain second harmonic component to a large extent even during internal fault, and shows a tendency of relative reduction because of the advancement of transformer's core material. It is, therefore, necessary to develop a new algorithm as well as a new technique for the effective and accurate discrimination. This paper deals with advanced algorithm, fuzzy logic based relaying by using flux differential, and a new fault detection criterion logic scheme by using wavelet transform. To comparative analysis of proposed techniques, the paper constructs power system model including power transformer, utilizing the EMTP, and collects data through simulation of various internal faults and magnetizing inrush.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.11a
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• pp.852-855
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• 2005

Structural Dynamic Modification(SDM) is a technique to improve structure's dynamic characteristics by adding and removing substructures or changing material properties and shape of structures. This paper describes SDM techniques applied to a large structure with too many DOFs. The goal of this SDM technique is to modify a targe structure efficiently for its natural frequencies to avoid excitation frequencies. In this case, models reduced by Component Mode Synthesis(CMS) method that is a coupling technique are used to analyze a large structure efficiently. This paper considers a helicopter deck model with 55,000 DOFs as an application.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.11b
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• pp.682-686
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• 2001

A fundamental structural design consideration for a vehicle is the overall vibration characteristics in bending and torsion. Vibration characteristics of a vehicle system are mainly influenced by dynamic stiffness of the vehicle body structure and material and physical properties of the components attached to the vehicle body structure. The first step in satisfying this requirement is to obtain a satisfactory dynamic model of the vehicle structure. In this paper. modeling techniques of the vehicle components are presented and the effects of the vehicle components on the vibration characteristics of the vehicle are investigated,