• 한국구조물진단유지관리공학회 논문집
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• 제25권5호
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• pp.68-75
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• 2021

본 연구에서는 콘크리트의 균열조건에 따른 수분 흡수 현상을 해석적으로 분석하였다. 흡수 시간의 증가에 따라 콘크리트 표면을 통해 흡수되는 수분의 양을 실험적으로 분석한 기존 연구 결과들을 바탕으로 2차원 유한요소해석 모델을 개발하였다. 고려된 균열조건은 균열 폭(0.1 mm, 0.3 mm), 균열 깊이(0 ~ 250 mm), 균열 간격(0 ~ 200 mm)이며 총 30개 모델에 대한 유한요소해석을 수행하였다. 유한요소해석을 수행한 결과, 콘크리트 균열부의 수분 흡수량 증가에 중요한 영향을 미치는 조건은 균열 폭 및 균열 깊이의 변화로 확인되었다. 또한 비균열 조건의 콘크리트에 비해 균열부에서 추가로 흡수되는 물의 양을 정량적으로 분석하기 위하여, 균열부 수분 흡수계수(S_crack) 개념을 도입하고 이를 추정하기 위한 예측 식을 제안하였다. 균열 깊이에 대한 분석 결과, 콘크리트 균열 폭과 관계없이 균열 깊이 150 mm 이하에서는 균열로 인한 수분 흡수가 활발하게 발생할 수 있음을 확인하였다. 따라서 외부에 노출된 철근콘크리트 구조물은 제설제와 같은 수용액 등의 흡수로 인하여 철근 부식이 발생할 수 있음을 고려하면, 실제 시설물의 균열 조건을 파악하기 위해서는 시설물의 점검 및 진단 시에 기존 균열 폭에 대한 조사뿐만 아니라 균열 깊이에 대한 조사도 함께 수행되어야 할 것으로 판단된다.

• Journal of Electrical Engineering and Technology
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• 제8권5호
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• pp.1146-1151
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• 2013

This paper deals with design consideration and validation of a new pole-slot combination for permanent magnet vernier machine (PMVM) with consequent pole (CP) rotor especially for extremely low speed servo applications. A 136pole-24slot PMVM with CP rotor is introduced and analyzed by 2D and 3D finite element analysis (FEA) and discussion on experimental validation is also included.

• 한국포장학회지
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• 제23권3호
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• pp.183-190
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• 2017

Carton clamp truck is widely perceived as the high-efficient handling equipment of factory premises and warehouse by its capability of palletless handling. Therefore, the significance of a lab-based handling simulation is becoming higher with the growth of clamp truck usage. In this study, preliminary FEA and design of handling test courses for the lab-based simulation of carton clamp truck handling were performed, and the PSD analyses were performed for the modified one for the test course proposed by Park et al. (2017) as well as ASTM D 6055 and ISTA 3B standards. For the vibration in all directions, the vibration energy intensity analyzed by ISTA 3B standard showed higher than that by the other two cases. A FEA was performed for the handling operation of the sudden stop of the clamps after lifting the target HCP (heavyweight refrigerator corrugated package, w=180 kgf) up to the specified height. The slip distance between the clamp arm and the target HCP was 0.85 mm. The simulation result of 0.85 mm was 3.7 times lower than the experimental result (3.2 mm) obtained by Park et al. (2017), and it was estimated that the deviation comes from both the experimental error by weight imbalance of target HCP, and excessive simplification during the FE modelling of target HCP.

• 구강회복응용과학지
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• 제21권1호
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• pp.1-14
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• 2005

The purpose of this study was to assess the loading distributing characteristics of implant prosthesis of internal connection system(ITI system) according to position and direction of load, under vertical and inclined loading using finite element analysis (FEA). The finite element model of a synOcta implant and a solid abutment with $8^{\circ}$ internal conical joint used by the ITI implant was constructed. The gold crown for mandibular first molar was made on solid abutment. Each three-dimensional finite element model was created with the physical properties of the implant and surrounding bone. This study simulated loads of 200N at the central fossa in a vertical direction (loading condition A), 200N at the outside point of the central fossa with resin filling into screw hole in a vertical direction (loading condition B), 200N at the centric cusp in a $15^{\circ}$ inward oblique direction (loading condition C), 200N at the in a $30^{\circ}$ inward oblique direction (loading condition D) or 200N at the centric cusp in a $30^{\circ}$ outward oblique direction (loading condition E) individually. Von Mises stresses were recorded and compared in the supporting bone, fixture, and abutment. The following results have been made based on this study: 1. Stresses were concentrated mainly at the ridge crest around implant under both vertical and oblique loading but stresses in the cancellous bone were low under both vertical and oblique loading. 2. Bending moments resulting from non-axial loading of dental implants caused stress concentrations on cortical bone. The magnitude of the stress was greater with the oblique loading than with the vertical loading. 3. An offset of the vertical occlusal force in the buccolingual direction relative to the implant axis gave rise to increased bending of the implant. So, the relative positions of the resultant line of force from occlusal contact and the center of rotation seems to be more important. 4. In this internal conical joint, vertical and oblique loads were resisted mainly by the implant-abutment joint at the screw level and by the implant collar. Conclusively, It seems to be more important that how long the distance is from center of rotation of the implant itself to the resultant line of force from occlusal contact (leverage). In a morse taper implant, vertical and oblique loads are resisted mainly by the implant-abutment joint at the screw level and by the implant collar. This type of implant-abutment connection can also distribute forces deeper within the implant and shield the retention screw from excessive loading. Lateral forces are transmitted directly to the walls of the implant and the implant abutment mating bevels, providing greater resistance to interface opening.

• 한국초전도ㆍ저온공학회논문지
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• 제16권4호
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• pp.57-61
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• 2014

Output fluctuation which is generated in wind power farm can hinder stability of total power system. The electric energy storage (EES) reduces unstable output, and superconducting magnetic energy storage (SMES) of various EESs has the proper performance for output compensation of wind power farm since it charges and discharges large scale power quickly with high efficiency. However, because of the change of current within SMES, the electromagnetic losses occur in the process of output compensation. In this paper, the thermal effect of the losses that occur in SMES system while compensating in wind power farm is analyzed. The output analysis of wind power farm is processed by numerical analysis, and the losses of SMES system is analyzed by 3D finite element analysis (FEA) simulation tool.

• Transactions on Electrical and Electronic Materials
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• 제14권3호
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• pp.143-147
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• 2013

This paper describes a low frequency driven electromagnetic energy harvester (EMEH) which consists of a thin flame resistant (FR-4) planar spring, NdFeB permanent magnets, and a copper coil. The FR-4 spring was fabricated using a desk computer numerical control (CNC) 3D modeling machine. Mathematical modeling and ANSYS finite element analysis (FEA) were used totheoretically investigate the mechanical properties of the spring mass system. The proposed EMEH generates a maximum power of 65.33 ${\mu}W$ at a resonance frequency of 8 Hz with an acceleration of 0.2 g (1 g = 9.8 $m/s^2$) and a superior normalized power density (NPD) of 77 ${\mu}W/cm^3{\cdot}g^2$.

• Restorative Dentistry and Endodontics
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• 제31권5호
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• pp.359-370
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• 2006

본 연구의 목적은 네 가지 형태의 비우식성 치경부 병소에 과다한 교합하중을 가했을 때 각 와동에 나타나는 응력 분포를 3차원적으로 조사하고자 하였다. 임상적으로 많이 관찰되는 다양한 형태의 병소 중 4가지 형태의 서로 다른 병소를 대표적으로 선택하여 발치된 상악 제2소구치에 3차원 유한요소 모형을 제작하였다. 형성된 모형에 협측교두와 설측교두에 500 N의 하중을 가한 후 치경부병소 첨부와 수직 절단면의 주 응력을 분석하여 다음과 같은 결과를 얻었다. 1 서로 다른 네 가지 형태의 와동에서 응력분포 양상은 비슷했지만 응력의 크기가 서로 달랐다. 2. 최대치 응력은 근심협측 우각부에서 나타났으며, 또한 병소의 첨부에 응력의 집중을 보였다. 3. 하중 A에서는 주된 응력이 압축 응력이었고 하중 B에서는 주된 응력이 인장 응력이었다. 4. 이러한 하중 하에서 수복치료를 하지 않으면 와동의 크기는 점차 커지고 치아구조에는 유해하게 작용하리라 생각된다.

• Journal of Electrical Engineering and Technology
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• 제12권1호
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• pp.256-261
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• 2017

This paper deals with the experimental evaluation on power loss of a double-side permanent magnet synchronous motor/generator (DPMSM/G) applied to a flywheel energy storage system (FESS). Power loss is one of the most important problems in the FESS, which supplies the electrical energy from the mechanical rotation energy, because the power loss decreases the efficiency of energy storage and conversion of capability FESS. In this paper, the power losses of coreless DPMSM/G are separated by the mechanical and rotor eddy current losses in each operating mode. Moreover, the rotor eddy current loss is calculated by the 3-D finite element analysis (FEA) method. The analysis result is validated by separating the power loss as electromagnetic loss and mechanical loss by a spin up/down test.

• 한국초전도저온공학회:학술대회논문집
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• 한국초전도저온공학회 2002년도 학술대회 논문집
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• pp.312-314
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• 2002

Magnetic circuit design of HTS (High Temperature Superconducting) motor is important to achieve the power at a given load condition, and it is essential to the thermal design for HTS motor rotors. To determine the result of thermal design, the magnetic field distribution has to be known exactly. On the basis of the 2 dimensional magnetic field analysis, the magnetic field distributions due to several cases are calculated by using Biot-Savart equation and magnetic image method. And the I$_{c}$ of HTS field coil was calculated by using I$_{c}$-B(equation omitted) curve and 3D FEA(Finite Element Analysis).is).

• Journal of Magnetics
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• 제21권4호
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• pp.577-585
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• 2016

In this paper, model of the axial-flux permanent magnet synchronous generator (AFPMSG) having arc-shaped trapezoidal permanent magnets (PM) is presented. The proposed model reduces the cogging torque and torque ripple, at the expense of lowering the average output torque. Optimization of the proposed model is performed by considering the asymmetric overhang configuration of the PMs, as to make the output torque of the proposed model competitive with the conventional model. The time stepped 3D finite element analysis (FEA) is performed for the comparative analysis. It is demonstrated that the torque ripple of the optimized model is highly reduced as well as average output torque is increased.