• 한국해양공학회지
• /
• 제37권6호
• /
• pp.256-265
• /
• 2023

Many numerical methods have been developed since 1961, but unresolved issues remain. This study developed a numerical method to address these issues and determine the coefficients and properties of rotational waves with a shear current in a finite water depth. The number of unknown constants was reduced significantly by introducing a wavelength-independent coordinate system. The reference depth was calculated independently using the shooting method. Therefore, there was no need for partial derivatives with respect to the wavelength and the reference depth, which simplified the numerical formulation. This method had less than half of the unknown constants of the other method because Newton's method only determines the coefficients. The breaking limit was calculated for verification, and the result agreed with the Miche formula. The water particle velocities were calculated, and the results were consistent with the experimental data. Dispersion relations were calculated, and the results are consistent with other numerical findings. The convergence of this method was examined. Although the required series order was reduced significantly, the total error was smaller, with a faster convergence speed.

• Journal of applied mathematics & informatics
• /
• 제42권2호
• /
• pp.321-331
• /
• 2024

We consider the numerical treatment of blow-up problems having non-monotonic singular solutions that tend to infinity at some point in the domain. The use of standard numerical methods for solving problems with blow-up solutions can lead to significant errors. The reason being that solutions of such problems have singularities whose positions are unknown in advance. To be able to integrate such non-monotonic blow-up problems, we describe and use a method of non-local transformations. To show the efficiency of the method, we present a comparison of exact and numerical solutions in addition to some comparison with the work of other authors.

• 한국분무공학회지
• /
• 제29권1호
• /
• pp.1-6
• /
• 2024

This paper is a numerical analysis study for evaluating the energy efficiency of electric vehicles. Currently, the methods for testing and evaluating the energy consumption efficiency of electric vehicles have limitations such as resources and time. Therefore, there is a need for research on developing models to predict the energy consumption efficiency of electric vehicles. In this study, a numerical analysis research is conducted to predict the energy efficiency of electric vehicles using a vehicle dynamics numerical analysis model. To validate the accuracy of the simulation model, it is compared the results of dynamometer tests with the simulation results and used the Unified Diagnostic Services (UDS) protocol to acquire internal data from the electric vehicle. It is ensured the reliability of the simulation model by comparing data such as motor speed, battery voltage, current, state of charge (SOC), regenerative braking power generation, and total driving distance of the test vehicle with dynamometer test data and simulation model results.

• 한국전산구조공학회논문집
• /
• 제20권1호
• /
• pp.83-92
• /
• 2007

대형의 유체-구조물 연계시스템(FSI) 해석을 위해 많은 수치기법들이 있지만, 유체의 슬로싱에 의해 발생되는 집중적이고 불규칙한 동수압의 영향 때문에, 신뢰할 수 있는 수치 결과와 수치안정성을 확보하기 위해 매우 조밀한 메쉬를 필요로 한다. 그 결과, 신뢰할 수 있는 장기적인 시간 응답을 구하기 위한 수치해석은 상당히 많은 CPU 시간을 요구한다. 본 논문의 목적은 국부 상세 모델을 이용하여 LNG운반선의 화물창 시스템의 유탄성적 거동을 해석하기 위한 전역-국부 해석기법을 제시하고자 한다. 본 논문에서 제시한 해석기법의 타당성을 증명하고 이 기법을 통해 LNG운반선 화물창 시스템의 국부응답을 효율적으로 예측한 결과를 제시하였다.

• 한국통신학회논문지
• /
• 제18권12호
• /
• pp.1935-1944
• /
• 1993

레이저 다이오드단면의 최적 무반사 코팅 조건을 활성층 두께의 함수로써 세가지 간단한 수치해석 방법을 사용하여 계산하였다. 세가지 간단한 수치해석 방법을 사용하여 얻은 결과가 서로 가른 것은 각 방법에서 사용한 레이저 다이오드내의 유효 굴절율이 다르기 때문이다. 또한 간단한 수치해석 방법의 정확성을 검토하기위하여 정확한 수치해석 결과와 그 결과들을 비교하였다. 레이저 다이오드의 유효 굴절율이 도과모드를 구성하는 각 편면파의 입사간도에 따라 변해 굴절율이 도파모드를 구성하는 각 평면파의 입사각도 따라 변화하도록 설정한 방법이 TE와 TM 모드에 대해서 또 활성층 굴절율과 클래딩층의 굴절율차가 작은 경우 클 경우 각각에 대하여 정확한 수치해석 결과와 잘 일치함을 알 수 있었다.

• 한국전산유체공학회지
• /
• 제19권3호
• /
• pp.52-61
• /
• 2014

The present paper deals with the efficient computation of higher-order CFD methods for compressible flow using graphics processing units (GPU). The higher-order CFD methods, such as discontinuous Galerkin (DG) methods and correction procedure via reconstruction (CPR) methods, can realize arbitrary higher-order accuracy with compact stencil on unstructured mesh. However, they require much more computational costs compared to the widely used finite volume methods (FVM). Graphics processing unit, consisting of hundreds or thousands small cores, is apt to massive parallel computations of compressible flow based on the higher-order CFD methods and can reduce computational time greatly. Higher-order multi-dimensional limiting process (MLP) is applied for the robust control of numerical oscillations around shock discontinuity and implemented efficiently on GPU. The program is written and optimized in CUDA library offered from NVIDIA. The whole algorithms are implemented to guarantee accurate and efficient computations for parallel programming on shared-memory model of GPU. The extensive numerical experiments validates that the GPU successfully accelerates computing compressible flow using higher-order method.

• Journal of the Korean Society for Industrial and Applied Mathematics
• /
• 제7권1호
• /
• pp.7-14
• /
• 2003

The main concern of this paper is to develop a new class of quasi-newton methods. These methods are intended for use whenever memory space is a major concern and, hence, they are usually referred to as limited memory methods. The methods developed in this work are sensitive to the choice of the memory parameter ${\eta}$ that defines the amount of past information stored within the Hessian (or its inverse) approximation, at each iteration. The results of the numerical experiments made, compared to different choices of these parameters, indicate that these methods improve the performance of limited memory quasi-Newton methods.

• 응용통계연구
• /
• 제25권6호
• /
• pp.1049-1058
• /
• 2012

Nonparametric methods are often used as an alternative to parametric methods to estimate density function and regression function. In this paper we consider improved methods to select the Bezier points in Bezier curve smoothing that is shown to have the same asymptotic properties as the kernel methods. We show that the proposed methods are better than the existing methods through numerical studies.

• 천문학논총
• /
• 제15권spc2호
• /
• pp.65-71
• /
• 2000

We have investigated the numerical methods to calculate model atmosphere for the analysis of spectral lines emitted from the sun and stars. Basic equations used in our calculations are radiative transfer, statistical equilibrium and charge-particle conservations. Transfer equation has been solved to get emitting spectral line profile as an initial value problem using Adams-Bashforth-Moulton method with accuracy as high as 12th order. And we have calculated above non linear differential equations simultaneously as a boundary value problem by finite difference method of 3 points approximation through Feautrier elimination scheme. It is found that all computing programs coded by above numerical methods work successfully for our model atmosphere.

• 한국생물정보학회:학술대회논문집
• /
• 한국생물정보시스템생물학회 2005년도 BIOINFO 2005
• /
• pp.237-242
• /
• 2005

Predicting the cellular location of an unknown protein gives a valuable information for inferring the possible function of the protein. For more accurate prediction system, we need a good feature extraction method that transforms the raw sequence data into the numerical feature vector, minimizing information loss. In this paper, we propose new methods of extracting underlying features only from the sequence data by computing pairwise sequence alignment scores. In addition, we use composition based features to improve prediction accuracy. To construct an SVM ensemble from separately trained SVM classifiers, we propose specificity based weighted majority voting. The overall prediction accuracy evaluated by the 5-fold cross-validation reached 88.53% for the eukaryotic animal data set. By comparing the prediction accuracy of various feature extraction methods, we could get the biological insight on the location of targeting information. Our numerical experiments confirm that our new feature extraction methods are very useful for predicting subcellular localization of proteins.