• 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.

• 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.

• 전자공학회논문지A
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• 제32A권1호
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• pp.45-52
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• 1995

A new Kirchhoff approximation(KA) method was proposed for microwave scttering from randomly rough surfaces. Using the spectral representation of delta function and its sifting theorem, a new KA was formulated directly without any further approximation, and this formulated was used to compute exact backscttering coefficients. The validity of the KA was verified by a numerical method, and this new KA technique was used to evaluate the existing approximated KkA methods; i.t., the zeroth-order and the first-order approximated physical optics(PO) models. It was shown that the first-order approximated PO model has small error than the zeroth-order approximated PO model at low incidence angles and the opposite happens at higher incidence angles. This new KA model can be used to compute exact scattering coefficients in the validity regions of KA and to evaluate other theoretical and numerical models for scattering from randomly rough surfaces.

• 한국정밀공학회지
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• 제22권5호
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• pp.55-62
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• 2005

This paper presents mainly a procedure to get the mathematical form of the manufactured aspherical lens. Generally Schulz formula describes the aspherical lens profile. Therefore, the base curvature, conic constant. and high-order polynomial coefficient should be set to get the approximated design equation. To find the best-approximated aspherical form, lens profile is measured by a commercial stylus profiler, which has a sub-micrometer measurement resolution. The optimization tool is based on the minimization of the root mean square of error sum to get the estimated aspherical surface equation from the scanned aspherical profile. Error minimization step uses the Nelder-Mead simplex (direct search) method. The result of the lens refractive power measurement shows the experimental consistency with the curvature distribution of the best-approximated aspherical surface equation

• 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].

• 한국전산유체공학회지
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• 제1권1호
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• pp.64-70
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• 1996

Three dimensional turbulent flow fields around ships are simulated by a numerical method. Reynolds Averaged Navier-Stokes equations are used where Reynolds stresses are approximated by Baldwin-Lomax and Sub-Grid Scale(SGS) turbulence models. Body-fitted coordinate system is introduced to conform three dimensional ship geometries. The governing equations are discretized by a finite volume method. Temporal derivatives are approximated by the forward differencing and the convection terms are approximated by the QUICK or Kawamura scheme. The 2nd-order centered differencing is used for other spatial derivatives. Pressure and velocity fields are simultaneously iterated by the Highly Simplified Marker-And-Cell method. To verify the numerical method and turbulence models, flow fields around ships are simulated and compared to the experiments.

• 한국정보전자통신기술학회논문지
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• 제1권2호
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• pp.33-38
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• 2008

심전도의 기저선 변동은 심전도의 P-파 및 Q,-, R-, S-파를 검출하기 어렵게 하는 원인이 된다. 본 연구에서는 기울기추적파를 이용하여 심전도의 기저선 변동을 제거하는 두 가지 방법에 대하여 제시하고 비교하였다. 첫 번째 방법은 이미 제안된 것으로 상승기울기에 의한 기울기추적파를 이용하여 기저선을 제거하는 방법이고 둘째 방법은 제안할 근사적인 S파의 궤적을 적용하는 방법이다. 이 두 가지 방법 모두 기울기추적파를 이용한 방법이지만, 전자는 상승기울기 추적파와 ECG와의 차신호를 구하는 방법이고, 후자는 하강기울기 추적파에서 얻은 근사적인 S파의 궤적을 이용하여 기저선을 제거하는 방법이다. 이 방법들을 판별하기 위하여 MIT/BIH 데이터베이스의 심전도를 대상으로 실험하였다.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 1995년도 추계 학술대회논문집
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• pp.148-153
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• 1995

Three dimensional turbulent flow fields around ships are simulated by a numerical method. Reynolds Averaged Navier-Stokes equations are used where Reynolds stresses are approximated by Baldwin-Lomax and Sub-Grid Scale(SGS) turbulence models. Body-fitted coordinate system is introduced to conform three dimensional ship geometries. The governing equations are discretized by a finite volume method. Temporal derivatives are approximated by the forward differencing and the convection terms are approximated by the QUICK or Kawamura scheme. The 2nd-order centered differencing is used for other spatial derivatives. Pressure and velocity fields are simultaneously iterated by the Highly Simplified Marker-And-Cell method. To verity the numerical method and turbulence models, flow fields around ships are simulated and compared to the experiments.

• 대한전자공학회논문지
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• 제27권6호
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• pp.921-928
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• 1990

A multivariable equalizer is designed which compensates transmission distortion for coaxial transmission line. The characteristic transfer function with bilateral parameter domain is approximated using the expansion method of orthonormal function and Gram Schmidt orthogonal function, but the parameter domain of approximated function is limited to unilateral. To solve that problem, Bode type transfer function is used to give bilateral variable characteristic to approximated function. The multivariable equalizer in this paper can be substituted for the current equalizer which consist of a fixed equalizer and a variable equalizer.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1991년도 한국자동제어학술회의논문집(국내학술편); KOEX, Seoul; 22-24 Oct. 1991
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• pp.208-212
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• 1991

LQG/LTR method cannot applied to nonminimum phase plant. In this paper, we present a new approximation method which guaratee the approximation error equal to zero and exact loop transfer recovery. Zero structure of plant and approximated plant are considered in approximation procedure. It is shown that the properties of plant and approximated plant at pole and zero frequency response are exactly same. It is shown by example that the suggested method can avoide the NMP plant constraint arised in designing LQG/LTR.