• Journal of the Microelectronics and Packaging Society
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• v.10 no.4
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• pp.61-64
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• 2003

The fractography was used to observe the stress profile on a single ion-exchanged glass. In the processing, the temperature was varied during the ion exchange, and then the stress profile on the single ion-exchanged glass was shifted from glass surface to slightly below the glass surface. The hackle mark and mirror surface were varied according to process conditions, and the glass strength was increased with increasing the number of hackle markers. In case of breaking the stress profile by using indenter, the breaking property was similar to the annealed glass.

• Proceedings of the Korean Fiber Society Conference
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• 2002.04a
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• pp.297-300
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• 2002

유리는 광학적으로 우수한 재료이나, 역학적 성질이 취약하여 이를 보완하기 위해 열처리 공정을 받게 된다. 열처리 공정에서 유리는 두께 방향으로 분포를 가지는 잔류 응력을 얻게 되고 이로부터 유리는 물성의 향성을 얻을 수 있다. 본 연구의 목적은 잔류 응력을 구하는 기존 방법[1]에 개선된 수치 해석법[2]을 도입하고, 보다 정확한 열변형율의 계산[2]을 통해, 기존의 잔류 응력 값[l]보다 향상된 잔류 응력 값을 구하는데 있다. (중략)

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 1997.04a
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• pp.181-187
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• 1997

고강도 알루미늄 합금 링롤재의 급냉, 링 팽창(expansion) 및 링 압축(compression) 응력제거처리후 잔류응력을 예측하기 위하여 2차원 축대칭 열해석 및 탄소성 해석을 수행하였다. 급냉 및 응력제거처리 후 2단 과시효 처리(T73)된 링롤재에 대하여 3단계 절단법(Three step sectioning method)을 적용하여 링롤재의 두께에 따른 잔류응력 분포를 측정하였으며, 측정결과를 급냉 및 응력제거처리후 잔류응력 해석결과와 비교분석하였다. 링의 급냉후 원주 및 축방향의 잔류응력 해석값은 T73후 측정값과 비슷한 경향을 보였으며, 링의 내면과 외면에서 압축응력을 나타내었고 중심에서 인장응력을 나타내었다. 잔류응력은 링 팽창(T7351) 및 링 압축(T7352) 적용후 T73에 비해 현저히 감소하였으며, 축방향의 제거 효과가 원주방향보다 우수하게 나타났다. 또한 링 압축에 의한 제거효과가 링 팽창보다 크게 나타났다. 링롤재의 응력제거처리는 제거 효과 및 실용성 측면에서 링 압축 공정이 유리하며, 치수제어 및 장비용량 측면에서 링 팽창 공정이 유리하다는 결론을 얻었다.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.50 no.7
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• pp.455-463
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• 2022

As the need for R&D for high reliability cameras, such as satellite cameras, increases, the reliability of the bonding strength properties between an opto-mechanical structure and an optical component has been secured through specimen tests. However, the widely used specimen shape is not suitable for the application of glass and glass-ceramic material, which is fragile, making it difficult to obtain accurate bonding properties due to stress concentration in glass parts before reaching the bonding strength limit. In this study, the stress distribution characteristics in the shear test condition for various specimen shapes were studied analytically, based on the test results of the glass material's own fracture. Through this, the shape characteristics capable of relieving the stress concentration of the glass part were derived, and the range of the bonding shear strength verifiable by the specimen test was improved.

• Journal of the Korean Ceramic Society
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• v.31 no.8
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• pp.902-910
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• 1994

Residual stress measurements were made for cylindrical glass rods to compare experimental results with the calculated values obtained by Instant Freezing Model. According to the photoelastic measurements, the stress ratio of surface compression and center tension was increased from 1.4 to 2.0 as the heat-treatment temperature was lowered, the fictitious forzen temperature was found to be closer to the heat-treatment temperature and the fictitious coefficient was increased.

• Journal of the Microelectronics and Packaging Society
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• v.4 no.2
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• pp.17-24
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• 1997

Spacer가 없는 Field Emission Display 정보표시소자의 진공 패키징시 패널 유리 두 께에 따른 패널 유리가 받는 응력과 패널의 중앙 부위에서의 변위를 계산하였다. 판의 각 모서리가 고정된 상태에서 일정한 압력을 받는 경우의 bending moment로부터 우리가 받는 압력을 계산하였으며 3.7"와 5.7"크기의 두가지 경우를 실험하여 계산값과 파괴양상 및 중앙 에서의 변위를 비교하였다.변위를 비교하였다.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.10 no.4
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• pp.330-336
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• 2000

Effects of microstructure and indentation stress on fracture behavior of glass-infiltrated alumina composite for dental restorative application were investigated by the Hertzian and Vickers indentation method. Indentation stress-strain curve of glass-infiltrated alumina has showed the quasi-plastic behavior - deviation from linearity at high stress and the classical Hertzian cone crack, which could be confirmed the subsurface damage micrographs using bonded-interface specimen technique. The indentation stress-strain curves for the starting preforms are strongly dependent on porosity and microstructure of the preforms. On the other hand, the curves for the infiltrated composites are relatively insensitive to these factors. The failure of composite is originated at quasi-plastic deformation region. Damage and fracture behavior due to Hertzian stress field is theoretically examined, so that the indentation stress field plays a great role in material degradation. After Hertzian indentation annealing processing changes fracture behavior of alumina composite, so that stress field in material is healed through annealing.

• The Journal of Engineering Research
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• v.2 no.1
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• pp.125-131
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• 1997

The regenerator is important part of the glass melting furnace to increase the temperature of the intake air through the combustion flame. The insulation, checker brick, prevention of the air leak has been studied to decrease the fuel consumption in glass melting industries. Thus the new types of checker brick and the design of the rider arch has been studied to prolong the life of the glass melting furnace. The height of the regenerator increased from 5.64 m to 7.89 m in the reforming of the glass melting furnace. Thus the stability of the rider arch is studied under the condition of increased load of checker brick in this research. The rider arch was estimated to be stable inspite of the increase of load according to the calculation. The max. sustained compressive stress of the rider arch is 163 kg/$cm^2$ and the max. sustained shear stress is 6.37 kg/$cm^2$.

• Korean Journal of Materials Research
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• v.8 no.12
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• pp.1121-1126
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• 1998

For vacuum seated panel, stresses and displacements in the glass plate were calculated. The geometric variables for our experiment were the thickness of glass plate, the size of panel and the width of sealing line. The fracture behaviors and displacements of its under the vacuum were measured. From the measurement of strains and fracture, it was considered that the maximum stress acted at the middle of the sides of the panel. The stresses and displacement distribution of manufactured panels were greatly dependent on the width of the sealing line in the panel. The measured values are more similar to the values which were calculated from the condition of built-in edge as the width of the sealing line is larger. The measured displacement of the panel, made of 3mm thick glass plate, with size of $80\Times120\textrm{mm}^2$ and 20mm sealing line was $57\mu\textrm{m}$. This value is similar to calculated value, $54\mu\textrm{m}$, from built- in edge condition in the finite element method.

• Proceedings of the KIEE Conference
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• 2003.07c
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• pp.1439-1441
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• 2003

전기절연재의 구조재로 많이 사용되고 있는 FRP(fiber reinforced plastics)는 열경화성 수지를 접착성 결합제(binder)로 하고 고강도 섬유를 보강재로 한 복합재료로서 기계적, 화학적, 전기적 특성이 매우 우수하다. FRP의 기계적 강도는 유리섬유에 의존 하고 있으므로 유리섬유의 방향과 힘을 가하는 방향에 따라서 그 강도의 차이는 매우 크게 나타난다. 본 연구에서는 섬유의 배향에 따른 강도의 변화를 이해하기 위하여 시편을 제작하여 압축강도를 측정하고 압축강도와 응력의 분포를 유한요소법으로 시뮬레이션하였다. FRP rod에 압축응력이 가해졌을 때 섬유의 배향에 따른 파괴강도와 응력의 분포를 유한요소법을 이용하여 시뮬레이션하였고 모델링에는 3-D Shell과 3-D Brick 요소를 사용하였다. 제작된 시편의 강도특성과 시뮬레이션을 통한 응력의 분포를 서로 비교하여 시편의 파괴에 미치는 응력을 고찰하였다.