• 한국군사과학기술학회지
• /
• 제10권4호
• /
• pp.38-51
• /
• 2007

This paper describes research results for the measurement and analysis method of magnetic signatures generated from the ship's magnetic mock-up model. In this paper, we present the theoretical and experimental techniques for the separation of the permanent and the induced magnetic field from the measured magnetic signature of the mock-up model. Also, we describe the prediction method of the induced magnetic field generated from mock-up model using the Magnet s/w, one of the FEM analysis tools for the electro-magnetic field and the magnetic dipole modelling method based on the least square techniques. The proposed modelling and analysis methods can be used for the prediction and the analysis of the static magnetic field generated from the real naval ship as well as the mock-up model.

• Journal of applied mathematics & informatics
• /
• 제25권1_2호
• /
• pp.345-351
• /
• 2007

Using more precise majorizing sequences we provide a finer convergence analysis than before [1], [7] of Newton's method in Riemannian manifolds with the following advantages: weaker hypotheses, finer error bounds on the distances involved and a more precise information on the location of the singularity of the vector field.

• 대한의용생체공학회:의공학회지
• /
• 제27권5호
• /
• pp.229-236
• /
• 2006

The acoustic field analysis method is the superior calibration method for rectifying the ultrasonic probe sensitivity. This method also can be applied to evaluate the probe performance in clinical fields without numerical analysis and precise measurements. In this paper, we propose the method of acoustic field pattern analysis with probe channel division for the evaluation of diagnostic ultrasound probe characterization. In order to verify our purpose, we performed a set of experiments. We measured the acoustic-field pattern of the three inferiority probes by channel division to evaluate an acoustic field distribution and impulse response characteristics. By comparing the results of acoustic field measurement method with that of conventional method such as impulse response and live image test for linear array probes, it is demonstrated that the ultrasound field measurement method is more effective then conventional method in detection of defective elements.

• Nuclear Engineering and Technology
• /
• 제30권3호
• /
• pp.202-211
• /
• 1998

Interfacial stresses at two-material interfaces and initial displacement field over the entire domain are obtained by modifying the potential energy functional with a penalty function, which enforces continuity of the stresses at the interface of two materials. Based on the initial displacement field and interfacial stresses, a new methodology to generate a continuous stress field over the entire domain has been proposed by combining the modified projection method of stress-smoothing and Loubignac's iterative method of improving the displacement field. Stress analysis is carried out on two examples made of dissimilar materials : one is a two-material cantilever composed of highly dissimilar materials and the other is a zirconium-lined cladding tube made of slightly dissimilar materials. Results of the analysis show that the proposed method provides an improved continuous stress field over the entire domain, and accurately predicts the nodal stresses at the interface, while the conventional displacement-based finite element method produces significant stress discontinuities at the interface. In addition, the total strain energy evaluated from the improved continuous stress field converges to the exact value in a few iterations.

• 한국농공학회:학술대회논문집
• /
• 한국농공학회 1998년도 학술발표회 발표논문집
• /
• pp.425-430
• /
• 1998

The theory of consolidation has been achieved remarkable development, but associated properties are very difficult to determine in the laboratory. The theoretical shortcomings of those consolidation theories and uncertainties of associated properties make inevitably some discrepancy between theoretical and field settlements. Field settlement measurement by settlement plate is, therefore, widely used to overcome the discrepancy. Among the various methods of ultimate settlement predictions using field settlement data, hyperbolic method and Asaoka's method are most commonly used because of their simplicity and ability to give a reasonable estimate of consolidation settlement. In this paper, the applicability of hyperbolic method and Asaoka's method has been estimated by the analysis of the laboratory consolidation test and field measured data. It is shown that both hyperbolic method and Asaoka's method are significantly affected by the direction of drainage, and Asaoka's method is better to reflect the properties of the soft foundation than hyperbolic method.

• 한국농공학회지
• /
• 제38권6호
• /
• pp.35-41
• /
• 1996

The theory of consolidation has been achieved remarkable development in terms of theory such as finite consolidation theory, two dimensional Rendulic consolidation theory. Though those theories are well defined, the analysis is by no means straightforward, because associated properties are very difficult to determine in the laboratory, Therefore Terzaghi's one dimensional consolidation theory and Barron's cylindrical consolidation theory are still widely used in engineering practice. The theoretical shortcomings of those consolidation theories and uncertainties of associated properties make inevitably some discrepancy between theoretical and field settlements. Field settlement measurement by settlement plate is, therefore, widely used to overcome the discrepancy. Ultimate settlement is one of the most important factor of embankment construction on soft soils. Nowadays the ultimate settlement prediction methods using field settlement data are widely accepted as a helpful tool for field settlement analysis of embankment construction on soft soils. Among the various methods of ultimate settlement prediction, hyperbolic method and Asaoka's method are most commonly used because of their simplicity and ability to give a reasonable estimate of consolidation settlement. In this paper, the reliability of hyperbolic method and Asaoka's method has been examined using analytical methods. It is shown that both hyperbolic method and Asaoka's method are significantly affected by the direction of drainage.

• 화약ㆍ발파
• /
• 제29권2호
• /
• pp.32-42
• /
• 2011

발파진동의 해석영역은 크게 두 가지 영역으로 구분될 수 있다. 첫째는, 대상 지장물에 대한 영향을 평가할 목적으로 시행되는 원거리 진동분석과, 둘째는, 암반의 손상 및 근거리 지중 구조물에 대한 영향을 평가할 목적으로 시행되는 근거리 지중진동 분석이 있다. 전자의 분석방법은 현재 국내외에서 보편적으로 활용되는 방법이며, 후자의 경우는 대체적으로 Holmberg모델을 사용하여 분석이 이루어져 왔고, 이 모델에 의해 제안된 방법은 기본적인 자료를 원거리 지표 진동 측정 데이터를 활용하는 방법을 근간으로 하여 분석이 이루어진다. 그러나, 최근 십수년동안 수행된 근거리 지중진동 실계측 결과에 따르면 Holmberg모델의 보완에 대한 필요성이 대두되었으며, 국내에서도 처음 시도되어 그 방향성을 제시하고자 하였으나 계측하는 방법에만 한정되었을 뿐 적정한 해석 모델 및 예측방법을 제시하지는 못했다. 따라서, 본 연구에서는 근거리 지중진동의 실계측을 통해 그 결과를 근간으로 하여 적정한 해석모델 및 예측방법을 제시하고자 하였다.

• 소성∙가공
• /
• 제18권7호
• /
• pp.550-555
• /
• 2009

In the multi-pass shape drawing process, the pass schedule that includes the determination of reduction ratio and intermediate die shape is very important. This study used the equal reduction, equal load, and electric field analysis method for pass schedule of the multi-pass shape drawing. The reduction ratio was calculated by the equal reduction and equal load method. And the intermediate die shape was determined by the result of the electric field analysis and the calculated reduction ratio. The proposed pass schedule method was applied to a shape drawing for producing cross roller guide. Finally, FE-analysis and shape drawing experiment were performed to verify the effectiveness of the proposed method.

• 대한조선학회논문집
• /
• 제55권5호
• /
• pp.394-400
• /
• 2018

Various numerical methods have been adopted for indoor noise assessments of ship plant. Acoustical radiosity method is one of the high frequency approaches for acoustic field analysis, which assumes diffuse reflections by boundaries so that it could be efficiently applied to the acoustically diffused indoor space noise analysis. In this study, an acoustic field analysis program has been developed based on radiosity method, which could apply for acoustically large enclosures such as ship's indoor space. For this purpose, the procedure of the acoustical radiosity method has been summarized and implemented to an acoustic field analysis program using MATLAB. Numerical example for a rectangular indoor space has investigated validity of the implemented program. Steady state sound pressure levels calculated for a continuous acoustic source signal have shown good agreement with those by other solutions such as an analytic solution and a ray tracing method. Instantaneous sound pressure levels calculated for an impulsive acoustic signal have provided the clues of direct/reflected acoustic field and reverberation time.

• 한국소성가공학회:학술대회논문집
• /
• 한국소성가공학회 2008년도 추계학술대회 논문집
• /
• pp.337-340
• /
• 2008

The cross section shape of intermediate die is one of important parameters to obtain dimensional accuracy of final product in shaped drawing process. Until now it has been designed by the experience or trial and error of the expert. In this study, the cross section shape of intermediate die fur spline shape is determined by the electronic field analysis, shape factor method. The result of the electronic field analysis, shape factor method has been compared with that of the present method. The effects of cross section shape on the dimensional accuracy were investigated by using FE analysis. And then the multi-stage shaped drawing experiments were performed to verify the results of FE analysis. As a result, the cross section shape from the electronic field analysis had the good dimensional accuracy. The electronic field analysis can be used for the method to obtain the cross section shape of intermediate die in shaped drawing process.