• 한국조명전기설비학회지:조명전기설비
• /
• 제11권6호
• /
• pp.74-80
• /
• 1997

본 논문에서는 저압 배전용 전선퓨즈의 I-t 특성을 다루었다. 전선퓨즈 엘리먼트는 과전류 영역을 담당하는 낮은 온도 용융영역(LTME)과, 대전류 영역을 담당하는 높은 온도 용융영역(HTME)으로 나누어 진다. 이들부분에 의하여 퓨즈의 용단특성이 결정되는 것이다. 따라서 이들 부분에 대한 열적, 전기적인 특성을 시뮬레이션하므로서, 퓨즈 엘리먼트 설계의 타당성을 이론적으로 검증하였다. 유한요소법(Finite Element Method)을 이용하여 전선퓨즈의 I-t특성을 시뮬레이션 하였다. 그리고 시뮬레이션 결과와 실혐결과를 비교해 보았을 때 대전류영역과 소전류영역에서의 상당히 유사한 결과를 얻을 수 있었다.

• 전기학회논문지
• /
• 제63권3호
• /
• pp.404-408
• /
• 2014

In this research we evaluate the excitation homogeneity and SAR of three different Tx arrays after B1+ Shimming in the human body at 3T. Through the simulations, we compared the field properties that are standard deviation and mean value of transverse magnetization for 1) strip line TEM array, 2) rectangular loop array, 3) combined array of strip line element and rectangular loop and shown the utilities of B1+ shimming in human body model. After B1+ shimming, it is evaluated four different types of SAR for body mesh through whole body simulation; those are average, maximum 1-cell, maximum 1-gram, and maximum 10-gram SAR. It appears that in this particular comparison an array based on strip line elements can produce better homogeneity and lower SAR than an array of rectangular loops or an array of combined elements (strip line and loop). While many factors are considered in designing coils for production, it is hoped that methods and results like these will be used in the future to guide decisions and maximize benefit.

• 대한기계학회논문집A
• /
• 제20권1호
• /
• pp.79-87
• /
• 1996

SMC(Sheet Molding Compound) is made of unsaturated polyester resin and other additives reinforced with randomly distributed chopped fiberglass strands. Because of its higher stiffness per unit mass, SMC was used as a substitute for steel for automotive steel outer panels. Thus, understanding of flow characteristics during fabrication of SMC is of importance since the formation of weld line depends on material flow. In the present study, SMC compression molding simulations in the flat and T-shape molds were accomplished. During simulations, the preferential the preferential flow occurred at the low mold closing speed while plug flow was observed for the higher mold closing speed. When the preferential flow was observed, the weld line was seen at the final stage. For simulations, rigid-viscoplastic finite element method was applied. Self-contact algorithm was also applied in order to predict the formation of the weld line. Simulation results were compared to the experimental results available in the literature.

• Wind and Structures
• /
• 제13권5호
• /
• pp.451-469
• /
• 2010

The majority of weather-related failures of transmission line structures that have occurred in the past have been attributed to high intensity localized wind events, in the form of tornadoes and downbursts. A numerical scheme is developed in the current study to assess the performance of transmission lines under tornado wind load events. The tornado wind field is based on a model scale Computational Fluid Dynamic (CFD) analysis that was conducted and validated in a previous study. Using field measurements and code specifications, the CFD model data is used to estimate the wind fields for F4 and F2 full scale tornadoes. The wind forces associated with these tornado fields are evaluated and later incorporated into a nonlinear finite element three-dimensional model for the transmission line system, which includes a simulation for the towers and the conductors. A comparison is carried between the forces in the members resulting from the tornadoes, and those obtained using the conventional design wind loads. The study reveals the importance of considering tornadoes when designing transmission line structures.

• 대한토목학회논문집
• /
• 제13권2호
• /
• pp.41-49
• /
• 1993

2차원 곡선보요소를 이용하여 대변형효과 및 탄소성거동을 고려한 유한요소법을 제시한다. Total Lagrangian 방법을 적용하며, 보요소는 평면응력요소로부터 유도된다. 또한, 임의의 단면을 갖는 평면뼈대 구조의 탄소성 해석을 수행하기 위하여 layered approach를 사용한다. 비선형 유한요소해석은 하중증분 또는 변위증분법을 적용한다. 본 연구에서 제안한 보요소의 거동과 정확도를 검증하기 위하여, 다른 문헌의 결과와 본 연구의 결과를 비교 분석한 해석예제를 제시한다.

• Wind and Structures
• /
• 제34권2호
• /
• pp.215-230
• /
• 2022

Majority of transmission line system failures at many locations worldwide have been caused by severe localized wind events in the form of tornadoes and downbursts. This study evaluates the structural response of two different transmission line systems under equivalent F2 tornadoes obtained from real incidents. Two multi-span self-supported transmission line systems are considered in the study. Nonlinear three-dimensional finite element models are developed for both systems. The finite element models simulate six spans and five towers. Computational Fluid Dynamics (CFD) simulations are used to develop the tornado wind fields. Using a proper scaling method for geometry and velocity, full-scale tornado flow fields for the Stockton, KS, 2005 and Goshen County WY, 2009 are developed and considered together with a previously developed tornado wind field. The tornado wind profiles are obtained in terms of tangential, radial, and axial velocities. The simulated tornadoes are then normalized to the maximum velocity value for F2 tornadoes in order to compare the effect of different tornadoes having an equal magnitude. The tornado wind fields are incorporated into a three-dimensional finite element model. By varying the location of the tornado relative to the transmission line systems, base shears of the tower of interest and peak internal forces in the tower members are evaluated. Sensitivity analysis is conducted to assess the variation of the structural behaviour of the studied transmission lines associated with the location of the tornado relative to the tower of interest. The tornado-induced forces in both lines due to the three different normalized tornadoes are compared with corresponding values evaluated using the simplified load case method recently incorporated in the ASCE-74 (2020) guidelines, which was previously developed based on the research conducted at Western University.

• 한국통신학회논문지
• /
• 제21권7호
• /
• pp.1756-1764
• /
• 1996

본 눈문에서는 buffered Banyan 네트워크에 적용되는 스위치 소자의 성능을 향상시키는 방안을 제안하고 제안된 스위치 소자의 성능을 측정하여 성능이 향상됨을 보였다. 기존의 buffered Banyan 네트워크의 스위치 소자에 FIFO(First In First Out) 버퍼를 채용하므로서 HOL(Heda-Of-Line) 블로킹이 발생하여 네트워크의 성능을 저하시킨다. 제안된 스위치 소자는 기본정보 이외의 보조정보를 이용하여 버퍼를 관리하는 CASO(Contents ASsociated Output)버퍼를 채용하므로서 HOL(Head-Of-Line) 블로킹의 발생을 제거하여 네트워크의 성능을 향상시켰다. 또한 성능측정을 위하여 buffered Banyan 네트워크의 해석모델인 MY 모델에 근거하여 제안된 네트워크를 해석하였고 이 관계식들을 이용하여 성능을 측정하였다.

• Journal of Magnetics
• /
• 제11권2호
• /
• pp.90-94
• /
• 2006

A finite-element method is used to analyze loss generation and electromagnetic noise absorption characteristics of a coplanar waveguide transmission line integrated with a magnetic thin film. Parameters used in the analysis are the electrical resistivity of the magnetic layer and the thickness of both magnetic and insulating layers. The results indicate that L-C resonance is the main loss mechanism of the electromagnetic noise absorption.

• 비파괴검사학회지
• /
• 제26권3호
• /
• pp.181-189
• /
• 2006

A 2D finite-element numerical simulation has been developed to investigate the generation of ultrasonic waves in a homogeneous isotropic elastic slab under a line-focused laser irradiation. Discussing the physical processes involved in the thermoelastic phenomena, we describe a model for the pulsed laser generation of ultrasound in a metal slab. Addressing an analytic method, on the basis of an integral transform technique, for obtaining the solutions of the elastodynamic equation, we outline a finite element method for a numerical simulation of an ultrasonic wave propagation. We present the numerical results for the displacements and the stresses generated by a line-focused laser pulse on the surface of a stainless steel slab.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2000년도 추계학술대회논문집A
• /
• pp.682-687
• /
• 2000

In this paper, the simulation methods using transmission lines are studied and realized, which are necessary in design and analysis of hydraulic control systems. The basic idea of this method is that system components are separated by transmission line element for simulation. The PI-controller can keep inductance level as low as desired. It can also handle nonlinearities and discontinuities without flag signal when restarting integration. Parallel hydraulic circuits are simulated using parallel processing algorithm. To shoe that using variable timestep size in each subsystem, simulation time can be reduced. Performance of the simulation results is compared with that of Runge Kutta method.