• 동력기계공학회지
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• 제7권2호
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• pp.11-16
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• 2003

Because of the advancement of digital computers and software technologies, simulation methods have been used to reduce time and costs. A lot of simulation methods have been developed for the improvement of charging efficiency on the intake and exhaust system of engines. In this study, as a basic step for the development of the gas flow simulation program for the intake and exhaust system, the gas flow in a pipe-orifice system was calculated with three algorithms(Method of Characteristics, MacCormack Method for conservation, and MacCoramck Method for nonconservation). The calculated results using three numerical algorithms were compared with measured result to verify the calculation accuracy.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2002년도 proceedings of the second asia international conference on tribology
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• pp.285-286
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• 2002

The lubricating characteristics of negative pressure slider were performed by using divergence formulation method with the coordinate transformation method. This method makes it possible to deal with an arbitrary configuration of a lubricated surface. The pressure profile of the slider is calculated. These results are compared to that from direct numerical method. The steady-state, including minimum film thickness, pitching and rolling angle are calculated by multi-dimensional Newton-Rapson method. The stiffness and damping characteristics are also calculated.

• KIEAE Journal
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• 제4권3호
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• pp.45-52
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• 2004

The purpose of this research was to identify the structural characteristics of open housing typologically and systematically. The main method of this study was content analysis and literature review on open housing. This study found that the typological analysis on terminology and the details of the constituents concerning structural patterns in open housing indicated that the main approaches were classified into three criteria such as 'Organization Element', 'Construction Element', and 'Equipment Element'. Organization Element was classified into 'Main Dwelling Unit Area and its Form', 'Room Organization Method', 'Relationship with the Main Dwelling Unit's External Constituents', and 'Combination Method of Support and Infill'. Construction Element was classified into 'Method of Structure' and 'Structural Element Technology'. Equipment Element was classified into 'Method of Using Duct' and 'Wet Zone Method'. The attributes were determined based on these classifications. The results of this study can be used to construct an evaluation tool and further to develop a framework in understanding open housing. Technical research should be conducted on the variables that affect the flexibility of space.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 춘계학술대회논문집
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• pp.688-693
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• 2002

Identification method is formulated to evaluate the dynamic characteristics of air bearings under NFR(Near Field Recording) sliders. Impulse responses and frequency response functions of NFR sliders are obtained on numerical non-linear models including rigid motion of slider and fluid motion of air bearing under the slider. Modal parameters and system parameters are identified by modal analysis method and instrumental variable method. The parameters of sliders are utilized to evaluate the dynamic characteristics of air bearings. Also, this study shows the difference between the dynamic characteristics of NFR and HDD slides, and squeeze effect of air bearings.

• 소음진동
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• 제7권5호
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• pp.847-852
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• 1997

Many investigations about the dynamic analysis of the structural system based on the BBA(Building Block Approach) method which predict dynamic characteristics of synthesized structures from each structure. But it is actually sometimes difficult to remove mounts from structures. In this paper, TFSM(The Transfer Function Separation Method) is developed which can predict dynamic characteristics of separated structures from the data of vibrational experiment of the synthesized structures. By combining TFSM with BBA, this paper also proposes the method which can predict dynamic characteristics of mount-modified structure without removing mounts from structures. And the proposed method is verified by the experimental data of plates.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 춘계학술대회논문집
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• pp.311-314
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• 2007

The experimental method of measuring dynamic properties of structures was presented. The method is based on the flexural wave propagation characteristics. Using the method, change in structural dynamic properties due to damage is measured. The crack has much more significant impact on the strain energy than the inertial effects. From this, the sensitivity of the dynamic stiffness on the crack location is estimated by calculating the strain energy. When the wave propagates, the strain and kinetic energies shows cyclic changed over space. The crack that occurred at locations where the wave energy is in the form of the potential energy affected most significantly the wave propagation characteristics. The effects of crack location on the wave propagation were used to determine the crack location.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2001년도 춘계학술대회논문집
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• pp.27-33
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• 2001

Linear harmonic analysis is a convenient and generally accurate method to use for the acoustic analysis of intake and exhaust silencers for IC engines. The major uncertainty in this form of modelling is the characterisation of the source, which is inherently nonlinear and time-variant. Experimental methods are generally used to determine the source characteristics, and in particular the indirect method is most suitable for an IC-engine source. With reference to an idealised linear time-variant source, it is found that the characteristics of a time-variant source as determined by the indirect method have no physical relevance. The direct method of experimental measurement appears to have some advantage over the indirect method, although in practice it is difficult to apply to an IC engine source. Again, an idealised linear time-variant source can be used to indicate that the characteristics of a time-variant source as determined by the direct method also have no physical relevance. Strangely, these meaningless measured source properties can nevertheless be used to accurately predict the radiated noise from an IC engine and silencer system.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2008년도 춘계학술대회논문집
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• pp.373-382
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• 2008

A method to investigate the design variable tolerance effects on the variances of the response, the characteristics, and the performance of a mechanical system is presented in this paper. The Monte-Carlo method has been conventionally employed to achieve such goals. However, the Monte-Carlo method has some serious drawbacks related to the computation time and the consistent solution convergence. To resolve the drawbacks of the method, a method employing sensitivity information is proposed. Sensitivity equations for a mechanical system are obtained analytically by differentiating the multi-body formulation with respect to a design variable. By using the chain rule along with the sensitivity information, the variances of the response, the characteristics, and the performance of a dynamic system can be calculated.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2008년 영문 학술대회
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• pp.80-83
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• 2008

Because of its advantages of simple structure, fast response speed, strong anti-pollution ability and good stability, high-speed solenoid valve has been widely used in aeroengine control systems, and some performances of the aeroengine control systems were affected directly by the response speed of high-speed solenoid valve. For some two-position two-way highspeed solenoid cone-valve, the paper discusses the establishment of its mathematical model and analyses its response characteristics by simulation model which is run in simulink of Matlab. Further more, a backstepping and segmentation method is used in the research of response characteristics, and the method is proved to be an accurate, fast and new method to get the influences of parameters on the valve s response characteristics.

• 융복합기술연구소 논문집
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• 제5권1호
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• pp.37-40
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• 2015

Numerical analyses on the aerodynamic characteristics of a counter rotating axial flow fan is carried out using the frequency domain panel method. Front rotor and rear rotor blades of a counter rotating axial fan are designed by using the simplified meridional flow analysis method with the radial equilibrium equation and the free vortex design condition, according to design requirements. Performance characteristics of a counter rotating axial flow fan are estimated for the variation of design parameters such as the hub to tip ratio, the taper ratio and the solidity. Pressure losses were higher at leading edge and hub region of rotor blades. Characteristic curve of the counter rotating fan was overpredicted without consideration of viscous effect.