• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 1999년도 학술대회논문집-국제 전기방전 및 플라즈마 심포지엄 Proceedings of 1999 KIIEE Annual Conference-International Symposium of Electrical Discharge and Plasma
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• pp.172-174
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• 1999

In this paper the approximated analysis method of industrial distribution system using PTW(Power Tools for Windows). System input data, cable impedance and transformer data etc., were calculated by the approximated method using EMTP(Electro Magnetic Transient Program). The effectiveness of this method was improved by electrical characteristics analysis of real factory.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1990년도 하계학술대회 논문집
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• pp.72-76
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• 1990

A new statistical linearization technique for nonlinear system called covariance matching method is proposed in this paper. The covariance matching method makes the mean and variance of an approximated output be identical real functional output, and the distribution of the approximated output have identical shape with a given random input. Also, the covariance matching method can be easily implemented for statistical analysis of nonlinear systems with a combination of linear system covariance analysis.

• 대한기계학회논문집
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• 제16권2호
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• pp.236-247
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• 1992

Optimization has been developed to minimize the cost function while satisfying constraints. Nonlinear Programming method is used as a tool for the optimization. Usually, cost and constraint function calculations are required in the engineering applications, but those calculations are extremely expensive. Especially, the function and sensitivity analyses cause a bottleneck in structural optimization which utilizes the Finite Element Method. Also, when the functions are quite noisy, the informations do not carry out proper role in the optimization process. An algorithm called "Second-order Approximation Method" has been proposed to overcome the difficulties recently. The cost and constraint functions are approximated by the second-order Taylor series expansion on a nominal points in the algorithm. An optimal design problem is defined with the approximated functions and the approximated problem is solved by a nonlinear programming numerical algorithm. The solution is included in a candidate point set which is evaluated for a new nominal point. Since the functions are approximated only by the function values, sensitivity informations are not needed. One-dimensional line search is unnecessary due to the fact that the nonlinear algorithm handles the approximated functions. In this research, the method is analyzed and the performance is evaluated. Several mathematical problems are created and some standard engineering problems are selected for the evaluation. Through numerical results, applicabilities of the algorithm to large scale and complex problems are presented.presented.

• Journal of Advanced Marine Engineering and Technology
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• 제33권1호
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• pp.28-36
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• 2009

In this paper, based on the measured data of hull deflection, an approximated hull deflection curve is drawn using reverse analyzed hull deflection data and the estimation method for flexibility analysis of shaft alignment is proposed by use of the approximate hull deflection curve. Generally an offset value of after stern tube bearing is a datum point with an fore stern tube bearing however the shaft alignment has a tendency which is able to get higher flexibility if the shafting system has the deflection value from after stern tube bearing as reference to bottom direction according to results of on this study. By applying this result of study, the shaft alignment for next similar ships will be able to estimate how to follow the hull deflection and how to be influenced by hull deflection at shaft alignment analysis state using the approximated hull deflection curve.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년 학술대회 논문집 정보 및 제어부문
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• pp.247-249
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• 2006

This paper describes a new method to eliminate the baseline wander for ECG based on waveform morphology analysis. This method uses the descending slope tracing waves[3] to separate the baseline wander from ECG and approximates the separated baseline wander to a corresponding approximated S-waves contour, and finally, subtracts the approximated S-waves contour from the original ECG. To verify its efficacy and validity in practical applications, this method has been applied to MIT/BIH database and compares this method with the other method employing the ascending slope tracing waves to remove a baseline from ECG[4].

• 대한전기학회논문지:전력기술부문A
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• 제51권3호
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• pp.127-133
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• 2002

This paper presents an efficient improvement of the iterative eigenvalue calculation method of the AESOPS algorithm. The intuitively and heuristically approximated iterative eigenvalue calculation method of the AESOPS algorithm is transformed to the Second Order Newton Raphson Method which is generally used in numerical analysis. The equations of second order partial differentiation of external torque, terminal and internal voltages are derived from the original AESOPS algorithm. Therefore only a few calculation steps are added to transform the intuitively and heuristically approximated AESOPS algorithm to the Second Order Newton Raphson Method, while the merits of original algorithm are still preserved.

• 한국정밀공학회지
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• 제21권1호
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• pp.197-204
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• 2004

In this study we presented kinematic and kinetic data of foot joints using approximated equations and partial plantar pressure during gait. The maximum angular displacements of each tarsometatarsal joint were found to range from 4$^{\circ}$to 7$^{\circ}$ and the maximum moments were from 200Nㆍcm to 1500Nㆍcm. It was relatively wide distribution. Foot kinematic data calculated from the approximated equations, which were represented by the correlation between moment and angular displacement, and the data from motion analysis were similar. We found that the movements of foot joint were mainly decided by the passive characteristics of the joint when ground reaction force acts. The method of kinematic and kinetic analysis using approximated equations which is presented in this study is considered useful to describe the movements of foot joints in gait simulations.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1998년도 추계종합학술대회 논문집
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• pp.363-366
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• 1998

High frequency scattered fields by a double impedence wedge are computed. In the procedure of the computation, arbitrary impedence faces and wedge angles are considered. The diffraction coefficients for the single, double and triple diffraction mechanism are founded. The second-order and third-order diffracted fields are approximated via the extended spectral ray method and the modified Pauli-Clemmow method of the steepest descent. The maliuzhinets function which is very difficult to obtain accurate value is approximated by the Volakis's asymtotic expression. Numerical computations are performed for the various wedge angles and surface impedence values.

• 한국CDE학회논문집
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• 제12권3호
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• pp.220-232
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• 2007

Current geometric modeling and analysis are commonly based on B-Rep modeling and a finite elements method respectively. Furthermore, it is difficult to represent an object whose material property is heterogeneous using the B-Rep method because the B-Rep is basically used for homogeneous models. In addition, meshes are required to analyze a property of a model when the finite elements method is applied. However, the process of generating meshes from B-Rep is cumbersome and sometimes difficult especially when the model is deformed as time goes by because the topology of deforming meshes are changed. To overcome those problems in modeling and analysis including homogeneous and heterogeneous materials, we suggest a unified modeling and analysis method based on implicit representation of the model using R-function which is suggested by Rvachev. For implicit modeling of an object a distance field is approximated and blended for a complex object. Using the implicit function mesh-free analysis is possible where meshes are not necessary. Generally mesh-free analysis requires heavy computational cost compared to a finite elements method. To improve the computing time of function evaluation, we utilize GPU programming. Finally, we give an example of a simple pipe design problem and show modeling and analysis process using our unified modeling and analysis method.

• 한국지반환경공학회 논문집
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• 제8권6호
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• pp.37-43
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• 2007

압밀현상을 예측하는데 있어, 압밀특성이 상이한 이질층의 존재 및 투수성에 대한 비선형 물질함수 특성을 고려하는 것은 기존 고전 압밀론에서의 많은 가정사항들을 극복하여 실제 현상에 더욱 부합하는 예측결과를 얻는데 있어 중요한 요소라 할 수 있다. 본 연구에서는 이질층에 대한 경계면 방정식을 유도하고, 이를 기존 유한차분해석기법에 포함시켜 이질층에 대한 압밀해석을 실시하였다. 또한 이질층을 단일토층으로 환산하여 압밀예측에 이용하는 기존방법과 본 연구에 의한 압밀해석 결과를 비교, 분석하였다. 한편, 유효응력단계별 투수성의 비선형성을 고려하기 위하여 기존 선형 압밀이론을 이용하되, 각 유효응력 단계별 압밀계수에 관한 함수식을 적용하는 근사 비선형 해석기법을 개발하여 본 압밀해석에 적용하였다.