• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.05a
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• pp.417-418
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• 2009

Aiming at time-dependent performance prediction of Liquid Rocket Engine(LRE) system, Program for Dynamic Characteristic Prediction of LRE is overviewed, and a modeling and dynamic analysis of rocket engine system with reference to developed transient simulator for LRE is outlined.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2004.04a
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• pp.191-196
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• 2004

This study proposed the analysis of mass position detection and modified stiffness due to the change of the mass and stiffness of structure by using the original and modified dynamic characteristics. The method is applied to examples of a cantilever and 3 degree of freedom by modifying the mass. The predicted detection of mass positions and magnitudes are in good agrement with these from the structural reanalysis using the modified mass.

• Speech Sciences
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• v.15 no.3
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• pp.7-15
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• 2008

This paper proposes the method to extract new feature vectors using the difference between the cepstrum for static characteristics and delta cepstrum for dynamic characteristics in speaker recognition (SR). The difference vector (DV) which it proposes from this paper is containing the static and the dynamic characteristics simultaneously at the intermediate characteristic vector which uses the deference between the static and the dynamic characteristics and as the characteristic vector which is new there is a possibility of doing. Compared to the conventional method, the proposed method can achieve new feature vector without increasing of new parameter, but only need the calculation process for the difference between the cepstrum and delta cepstrum. Experimental results show that the proposed method has a good performance more than 2.03%, on average, compared with conventional method in speaker identification (SI).

• Journal of the Korean Society of Safety
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• v.7 no.2
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• pp.71-79
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• 1992

This paper presents a least-square algorithms of lattice structures and their use for adaptive prediction of time series generated from the dynamic system. As the view point of adaptive prediction, a new method of Identification of dynamic characteristics by means of estimating the parameters of linear auto regressive model is proposed. The fast convergence of adaptive lattice algorithms is seen to be due to the orthogonalization and decoupling properties of the lattice. The superiority of the least-square lattice is verified by computer simulation, then predictor coefficients are computed from the linear sequential time data. For the application to the dynamic characteristic analysis of unknown system, the transfer function of ideal system represented in frquency domain and the estimated one obtained by predicted coefficients are compared. Using the proposed method, the damping ratio and the natural frequency of a dynamic structure subjected to random excitations can be estimated. It is expected that this method will be widely applicable to other technical dynamic problem in which estimation of damping ratio and fundamental vibration modes are required.

• 연구논문집
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• s.23
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• pp.5-13
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• 1993

The present work deals with the theoretical prediction of static & dynamic characteristic of annular type externally pressurized thrust air bearings with metal-sintered porous media. For the evaluation of surface loading effect by machining, it is assumed that the flow at the porous surface is dominant and which is equivalent to the flow through orifice. Finite different method with over-relaxation method is used to solve the numerical problems. The influences of radius ratio, supply pressure and squeeze number on performances are investigated, as the results. The results of this study can be used to predict the optimal running condition and stable realm of porous bearings.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.11a
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• pp.459-468
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• 2009

Analysis of the uncertainty to have engineering solution of gas-dynamic and hydrodynamic problems is based on the comparison the prospective engineering solution with experimental result. In this paper, the mathematical model to estimate heat flux along gas-dynamic channel wall and the solution sequence are shown. Statistical information and generalizing experimental characteristics about gas- and hydro-dynamic channels were applied to the mathematical model. As the results, it is possible to draw a conclusion that models of the integrated approach, using the averaged statistical data of generalizing characteristics for a turbulent flow, without consideration of the turbulent mechanism (characteristic pulsations), can predict a nominal operating regime for gas-dynamic and hydrodynamic systems. The probable deviation of operating regime for newly designed the gas-dynamic channel can achieve 20% from a regime predicted on a basis 1-D or 3-D modelling irrespective of a kind of used models.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.6 s.171
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• pp.144-151
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• 2005

Spin coater is regarded as a major module rotating at high speed to be used build up polymer resin thin film layer fur bonding process of GaAs wafer. This module is consisted of spin unit for spreading uniformly, align device, resin spreading nozzle and et. al. Specially, spin unit which is a component of module can cause to vibrate and finally affect to the uniformity of polymer resin film layer. For the stability prediction of rotation velocity and uniformity of polymer resin film layer, it is very important to understand the dynamic characteristics of assembled spin coater module and the dynamic response mode resulted from rotation behavior of spin chuck. In this paper, stress concentration mode and the deformed shape of spin chuck generated due to angular acceleration process are presented using analytical method for evaluation of structural safety according to the revolution speed variation of spin unit. And also, deformation form of GaAs wafer due to dynamic behavior of spin chuck is presented fur the comparison of former simulated results.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.15 no.5
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• pp.337-345
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• 2003

In the case of heat exchangers operating under frosting condition, the growth of frost layer causes the heat exchanger to increase the thermal resistance and pressure loss of the air flow. In this paper, a transient characteristic prediction model of the heat transfer for multi inverter heat pump with frosting on its surface was presented taking into account the change of the fin efficiency due to the growth of the frost layer. In this dynamic simulation program, which was peformed for a basic air conditioning system model, such as evaporator, condenser, compressor, linear electronic expansion valve (LEV) and bypass circuit. The theoretical model was driven from the obtained heat transfer coefficient and mass transfer coefficient, independently. And we consider heat transfer performance was only affected by a decrease of the wind flow area. The calculated results were compared with some cases of experiments for frosting conditions.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.11a
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• pp.287-293
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• 2010

본 연구에서는 개방형 로켓엔진시스템의 제어시스템을 구성하기 위한 선행연구로서, 시동특성을 예측하기위해 Simulink 모델을 구성하였다. 구성품별 동특성 모델을 바탕으로 로켓엔진시스템의 예측 프로그램을 구성하였으며, 대상으로 하는 시스템의 천이 작동상태에서의 동특성 변화의 예측과 더불어 그 모델링의 타당성 검증을 위하여 실제 개방형 로켓엔진 상사모델의 수류실험을 통해 실험적으로 측정하여 비교하였다. 또한 Simulink모델이 제어시스템을 구성하기위해 적합한지를 판단하기위해 기 수행된 천이 동특성 예측 프로그램의 결과와 비교하였고 검증하였다.

• Proceedings of the KSR Conference
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• 2001.05a
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• pp.147-154
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• 2001

Dynamic behavior of high speed train is very important because the high speed train should be safe and satisfied with the ride comfort. An eddy current brake system is mounted on trailer bogie and wheelset. The eddy current braking force longitudinally exerts on the articulated trailer bogie and the attraction force vertically exerts on the wheelset. Because a frame of eddy current brake system is flexible, these forces generate the vertical vibration at middle point of the frame. Also, the vibration change the vertical clearance between an electromagnet and top of rail which affect the magnitude of braking and attracting forces. Therefore, the dynamic behavior of the eddy current braking system must be predicted for design the dynamic characteristic of its mounting system when normally operate on rail which have irregularity. Vampire program is used for Prediction of the dynamic behavior of an eddy current braking system.