• 한국자기학회지
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• 제22권3호
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• pp.97-102
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• 2012

본 논문은 전선을 통하여 전력을 전달하는 일반적인 전력전송방식이 사용될 수 없는 환경에서 무선으로 전력을 전송하는 비접촉 전력전송기기 개발에 관한 것이다. 전력전송 방식은 자기공명방식보다 큰 전력을 전송하기에 적합한 전자기유도방식을 이용 하였다. 전력전송기기의 설계 방법은 전기장하(Electirc loading)와 자기장하(Magnetic loading)의 비율로 코어와 코일을 설계하는 장하분배법(Loading Distribution Method)으로 설계 하였고 유한요소법(Finite Elements Method)으로 기기에 발생하는 전자기장을 해석하여 설계한 전력전송기기의 적합성을 판단하고 적정한 설계치를 보정하였다. 본 연구를 통하여 개발된 전력전송방식은 비접촉식으로 수 mm 거리를 가지는 근거리에서 무선으로 전력을 전송하기에 적합함을 보였다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2010년도 추계학술대회 논문집
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• pp.223-224
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• 2010

• Journal of Welding and Joining
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• 제34권2호
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• pp.11-15
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• 2016

FE analyses for weldment of ship structure are required for various reasons such as stress concentration for bead tow, residual stress and distortion after welding, and hydrogen diffusion for prediction of low temperature crack. These analyses should be done by solid element modeling, but most of ship structures are modeled by shell element. If we are able to make solid element in the shell element FE modeling it is easily to solve the requirement for solid elements in weld analysis of large ship structures. As the nodes of solid element cannot take moments from nodes of shell element, these two kinds of element cannot be used in one model by conventional modeling. The PSCM (Perpendicular shell coupling method) can connect shell to solid. This method uses dummy perpendicular shell element for transferring moment from shell to solid. The target of this study is to develop a FE pre-processing system applicable at welding at ship structure by using PSCM. We also suggested glue-contact technique for controlling element numbers and element qualities and applied it between PSCM and solid element in automatic pre-processing system. The FE weldment modeling through developed pre-processing system will have rational stiffness of adjacent regions. Then FE results can be more reliable when turn-over of ship-block with semi-welded state or ECA (Engineering critical assessment) of weldment in a ship-block are analyzed.

• 대한기계학회논문집A
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• 제33권2호
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• pp.153-161
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• 2009

Three-dimensional finite-element methods(FEM) have been used to analyze the thermal stress of an exhaust gas recirculation(EGR) cooler due to thermal and pressure load. Since efficiency and capability of the heat exchanger are mainly dependent on net heat transferring area of the EGR cooler system, the tube inside the system has a numerous dimples on the surface. Thus for finite element analysis, firstly the dimple-typed tube is modeled as a plain element without the dimple, and then the equivalent thermal conductivities and elastic modulus are calculated. This work describes the numerical homogenization procedure of the dimple-typed tube and verifies the equivalent material properties by comparison of a single unit and the actual full model. Finally, the homogenization scheme presented in this study can be efficiently applied to finite element analyses for the thermal stress and deformation behavior of the EGR cooler system with the dimple-typed tube.

• Computers and Concrete
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• 제21권5호
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• pp.547-557
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• 2018

This paper measures the mechanical response of precast pavement joints under moving axle loads using the finite-element method, and the models were validated with results of field tests. In order to increase the ability to use the non-linear FE analysis for design and assessment of precast pavement subjected to moving axle load, this paper investigated the effects of different load transfer between the slabs using the ABAQUS finite-element package to solve the nonlinear explicit model equations. The assembly of the panels using dowels and groove-tongue keys has been studied to assess the efficiency of keyway joint system. Concrete damage plasticity model was used to calculate the effects of permanent damages related to the failure mechanisms. With aggregate interlock as the only load transferring system, Load transfer efficiency (LTE) is not acceptable when the axle load reaches to slab joints. The Finite-element modelling (FEM) results showed that keyway joints significantly reduced tensile stresses developed at the mid-slab. Increasing the thickness of the tongue the LTE was improved but with increasing the height of the tongue the LTE was decreased. Stresses are transferred to the adjacent slab efficiently when dowels are embedded within the model. When the axle load approaches joints, tensile damage occurs sooner than compressive damage, but the damage rate remains constant, then compressive damage increases significantly and become the major form of distress under the dowels.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1988년도 전기.전자공학 학술대회 논문집
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• pp.247-249
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• 1988

The most space-consuming element of digital image processing system is the video memory. Though this problem is solved by DRAMs, timing constraints posed by video data rates. The cycle time of DRAMs can be diminished by serial transferring and reading or writing pixel datas at the same time. This paper resents the design of 1024${\times}$512 video memory using this technique.

• Structural Engineering and Mechanics
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• 제86권2호
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• pp.261-276
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• 2023

The use of the ordinary double nut (i.e., ODN) composed of a master nut (i.e., M-nut) and a slave nut (i.e., S-nut) is a highly efficient method to prevent bolts loosening. A novel double nut (i.e., FODN) composed of a master nut (i.e., M-nut) and flat slave nut (i.e., FS-nut) is proposed to save raw materials. The bolt fastening tests with single nut, ODN and FODN are performed to investigate the preload and counterbalance forces. Corresponding finite element analysis (FEA) models are established and validated by comparing the preload with the experimental results. The load-bearing capacity, the extrusion effect, and the contact stress of each engaged thread for ODN and FODN are observed by FEA. The experimental and simulated results revealed that the bolt fastening with double-nut has different load-transferring mechanisms from single-nut. Nevertheless, for double-nut/bolt assemblies, the FS-nut can provide load transfer that is like that of the S-nut, and the FODN is a reasonable and reliable fastening method. Furthermore, based on the theory of Yamamoto, a formula considering the extrusion effect is proposed to calculate the preload distribution of the double-nut, which is applicable to varying thicknesses of slave-nuts in double-nut/bolt assemblies.

• 한국전산구조공학회논문집
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• 제12권3호
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• pp.363-370
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• 1999

본 연구에서는 철근콘크리트기둥과 철골보로 이루어진 혼합구조 접합부의 해석에 대한 유한 유소법을 이용한 해석 모델 방법을 제시하였다. 혼합구조 접합부에서 콘크리트와 강판이 접하는 접촉면은 두 접촉면 사이를 부착과 마찰의 개념으로 표현할 수 있는 주-종속 접촉 알고리즘(master-slave contact algorithm)을 이용하여 모델링하였다. 그리고, 휨응력의 지배를 받는 강관에는 비적합 모드 요소를 사용하였다. 본 연구에서의 혼합구조 특징은 보에서 기둥으로 힘의 전달을 원활히 하기 위하여 다이아프램이 사용되었고, 이러한 혼합구조 접합부 모델링 방법에 대한 타당성을 알아보기 위하여 3차원 비선형 해석을 행하여 실험결과와 비교한 결과 잘 일치하는 결과를 얻었다.

• 한국지반공학회논문집
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• 제18권4호
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• pp.249-256
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• 2002

Slurry trench의 안정성은 안정액의 유압이 filter cake 막을 통하여 trench 벽에 전달됨으로서 확보될 수가 있다. 지반조건의 영향에 따른 slurry trench 공법에서 주변 공극수압의 변화를 수치해석(FEM)으로 추적하였다. 이러한 주변 공극수압의 변화 요인으로는 안정액의 밀도, filter cake의 상태, 토질조건, 시간, trench 심도, 주변지하수위로 조사되었으며, 가장 큰 영향력을 보인 요인으로는 토질조건과 filter cake 상태로 나타났다.

• Journal of Magnetics
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• 제14권4호
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• pp.175-180
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• 2009

This paper describes the design and analysis of a tubular linear actuator for intelligent AAP (Active Accelerate Pedal) system. In a driving emergency, the electromagnetic actuator produces an additional pedal force such as the active pedal force and vibration force to release the driver's foot on accelerator pedal. A prior study found that the linear actuator with a ferromagnetic core had a problem in transferring the additional force naturally to a driver due to the cogging force. To reduce the cogging force and obtain higher performance of the AAP system, a coreless tubular linear actuator is suggested. Electromagnetic finite element analysis is executed to analyze and design the coreless tubular actuator, and dynamic analysis is performed to characterize the dynamic performance of the AAP system with the suggested tubular actuator for two types of thrust force.