• 한국소음진동공학회논문집
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• 제11권9호
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• pp.454-461
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• 2001

Acoustic noise and vibration of a BLDC motor is a coupled phenomenon between mechanical characteristics and electromagnetic origins through the motor air-gap. When a relative misalignment of rotor in the air-gap center exists on the assemblage, it is considered to influence the motor system characteristics. In this paper, the back electro motive force(BEMF) is analyzed by Finite Element Method(FEM) and verified by experiments for the SPM and IPM type motors. For magnetic field analysis, a FEM is used to account for the magnetic saturation. Using these results, the FEM is made to determine the appropriate electromagnetic field analysis in BLDC motors with rotor eccentricity ratio. A radial magnetic imbalance force of BLDC motor with rotor eccentricity is analyzed. Results demonstrate that the imbalance force is increased according to the degree of misalignment. An IPM motor, mostly chosen to realize high-speed operation, shows a worse effect on magnetic unbalanced forces and dynamic responses compared with SPM motor due to magnetic saturation when the rotor eccentricity exists.

• 한국자기학회지
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• 제20권6호
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• pp.239-243
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• 2010

본 논문은 반응표면법(Respone Surface Methodology)과 유한요소법(Finite Element Method)을 이용하여 250 kW급 견인 유도 전동기의 효율 향상을 위한 최적설계기준에 대해서 다루었다. 본 논문의 주 관점은 첫째, 회전자 형상 및 치수변화에 따른 토크 비교를 통해 설계 해를 찾는 것이다. 둘째, 중심합성법(Central Composite Design)과 결합된 해석방법이 도입되었고, 추정된 회귀모델의 적합성을 결정하기 위해 분산분석(Analysis Of Variance)이 수행되었다. 이렇게 제안된 실험 절차는 기존의 초기 모델로 부터 시작하여 회전자 형상 및 치수를 최적설계 하였다.

• Structural Engineering and Mechanics
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• 제54권4호
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• pp.607-622
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• 2015

This paper presents a comparative study of analytical method and finite element method (FEM) for analysis of a continuous contact problem. The problem consists of two elastic layers loaded by means of a rigid circular punch and resting on semi-infinite plane. It is assumed that all surfaces are frictionless and only compressive normal tractions can be transmitted through the contact areas. Firstly, analytical solution of the problem is obtained by using theory of elasticity and integral transform techniques. Then, finite element model of the problem is constituted using ANSYS software and the two dimensional analysis of the problem is carried out. The contact stresses under rigid circular punch, the contact areas, normal stresses along the axis of symmetry are obtained for both solutions. The results show that contact stresses and the normal stresses obtained from finite element method (FEM) provide boundary conditions of the problem as well as analytical results. Also, the contact areas obtained from finite element method are very close to results obtained from analytical method; disagree by 0.03-1.61%. Finally, it can be said that there is a good agreement between two methods.

• 한국진공학회지
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• 제17권6호
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• pp.487-494
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• 2008

준 2차원 수치적 모델을 사용하여 침-평판(point-plane)형의 전극 사이에 있는 중간 압력 질소의 방전에 대한 시뮬레이션을 수행하였다. 이 모델에서는 전자와 이온에 대한 연속방정식을 풀어 시. 공간적으로 변하는 전하분포를 계산하고, 공간 전하 분포의 변화에 따라 결정되는 전기장은 푸아송 방정식을 풀어 얻는다. 연속 방정식은 FCT (Flux-corrected transport) 알고리즘과 FEM (Finite Element Method) 방법을 적용하여 수치적으로 다루어 졌다. 50Torr 압력에서의 질소 방전에 대한 시뮬레이션 결과는 중간 압력 질소 방전의 물리적 특성에 관한 상세한 이해를 제공한다. 또 계산 결과와 실험 결과[1]와의 비교는 정성적으로 잘 일치하는 것을 보여 준다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 춘계학술대회 논문집 방전 플라즈마 유기절연재료 초전도 자성체연구회
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• pp.125-129
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• 2004

The mold transformers have been widely used in underground substations in large building and have some advantages in comparison to oil-transformer, that is low fire risk, excellent environmental compatibility, compact size and high reliability. In addition, the application of mold transformer for outdoor is possible due to development of epoxy resin. The mold transformer generally has cooling duct between low voltage coil and high voltage coil. A mold transformer made by one body molding method has been developed for small size and low loss, but it needs some cooling method because heat radiation between each winding is difficult. The life of transformer is significantly dependent on the thermal behavior in windings. Many transformer designers have calculated temperature distribution and hot spot point by FEM(finite element method) to analyze winding temperature rise. In this paper, the temperature distribution and thermal stress analysis of 100kVA pole cast resin transformer for power distribution are investigated by FEM program.

• 한국도로학회논문집
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• 제18권2호
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• pp.11-18
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• 2016

PURPOSES: This paper investigates behavior and performance of concrete pavement in tunnel based on temperature data from field. METHODS : In this study, there are 4 contents to evaluate concrete pavement in tunnel, First, Comparison for distress was conducted at outside, transition, and inside part of tunnel. Secondly, temperature data was collected in air and inside concrete pavement in outside and inside tunnel. Thirdly, FEM analysis was performed to evaluate stress condition, based on temperature data from field. Finally, performance prediction was done with KPRP program. RESULTS: From the distress evaluation, failure of inside tunnel was much less than it of outside tunnel, Temperature change in tunnel was less than out side, and also it was more stable. According to result of FEM analysis, both curling stress status of inside tunnel was lower than it of outside tunnel. Based on KPRP program analysis, performance of inside tunnel was longer than outside. CONCLUSIONS : Through all study about behavior and performance of concrete pavement in tunnel, condition in tunnel has more advantages from environmental and distress point of view. Therefore, performance of inside tunnel was better than outside.

• Journal of Welding and Joining
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• 제16권1호
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• pp.52-62
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• 1998

Laser beam welding of zinc-coated steel, especially lap joints, has a problem of zinc vapor produced during welding which has a low vaporization temperature of 906.deg. C. It is lower than the melting temperature of steel (1500.deg. C). The high pressure formed by vaporization of zinc during laser welding splatters the molten pool and creates porosities in weld. During laser lap welds of zinc-coated steel sheets with CW CO$_{2}$ laser the gap size has been analyzed and simulated using a FEM. The simulation has been carried out in the range of gap aetween 0 and 0.16 mm. The vaporized zinc gas has effected to prevent heat from conducting toward the bottom of sheets. In vaporized zinc gas has effected to prevent heat from conducting toward the bottom of sheets. In the case of too small gap size, zinc gas has not ejected and existed between two sheets. Therefore heat was difficult to conduct from the upper sheet to lower sheet and the upper sheet could over-melted. In the case of large gap size the zinc gas has been prefectly ejected but only a part of lower sheet has melted. The optimum range of gap size in the lap welds of zinc-coated steel sheets has been calculated to be between 0.08 and 0.12 mm. According to the comparison of experiment, the simulation is proved to be acceptable and applicable to laser lap welds.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 추계학술대회논문집
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• pp.820-825
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• 2004

This paper deals with friction-induced vibration of disc brake system under constant friction coefficient. A linear, finite element parameter model to represent the floating caliper disc brake system is proposed. The complex eigenvalues are used to investigate the dynamic stability and in order to verify simulations which are based on the FEM model, the experimental modal test and the dynamometer test are performed. The comparison of experimental and simulation results shows a good agreement and the analysis indicates that mode coupling due to friction force is responsible for disc brake squeal. And squeal type instability is investigated by using the parametric rotor simulation. This indicates parameters which have influence on the propensity of brake squeal. This helped to validate the FEM model and establish confidence in the simulation results. Also they may be useful during real disk brake model.

• 한국기계가공학회지
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• 제18권11호
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• pp.47-56
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• 2019

A deep neural network (DNN) model was proposed to predict the upset in the inertia friction welding process using a database comprising results from a series of FEM analyses. For the database, the upset length, upset beginning time, and upset completion time were extracted from the results of the FEM analyses obtained with various of axial pressure and initial rotational speed. A total of 35 training sets were constructed to train the proposed DNN with 4 hidden layers and 512 neurons in each layer, which can relate the input parameters to the welding results. The mean of the summation of squared error between the predicted results and the true results can be constrained to within 1.0e-4 after the training. Further, the network model was tested with another 10 sets of welding input parameters and results for comparison with FEM. The test showed that the relative error of DNN was within 2.8% for the prediction of upset. The results of DNN application revealed that the model could effectively provide welding results with respect to the exactness and cost for each combination of the welding input parameters.

• Journal of Magnetics
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• 제15권2호
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• pp.74-77
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• 2010

This paper deals with optimum design criteria for maximum torque density & minimum torque ripple of a Flux Switching Motor (FSM) using response surface methodology (RSM) & finite element method (FEM). The focus of this paper is to find a design solution through the comparison of torque density and torque ripple which vary with rotor shape. And then, a central composite design (CCD) mixed resolution was introduced and analysis of variance (ANOVA) was conducted to determine the significance of the fitted regression model. The proposed procedure allows one to define the rotor dimensions, starting from an existing motor or a preliminary design.