• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.3
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• pp.555-564
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• 1994

This study has been made to investigate the stress distribution around defects and inclusions that behave as stress concentrators. The stress distribution and interation effects around defects and inclusions was analyzed using Finite Element Method. The results are as follows;(1) Maximum stress point in case of $E_I/E_M>1$($E_I$:elasticity modulus forthe inclusion, $E_M$/:elasticity modulus for the base material)is the vertical point with respect to force direction and in case of $E_I/E_M<1$ it is the parallel point along the hole edge. (2) Interaction effects of ${\sigma}_y$ for the inclusion side is larger than the defect side when the interval between inclusion and defect is near. (3) stress interation effects is large if the difference of ${\sigma}_y$ is small and it is small if the difference of ${\sigma}_y$ is large for the case that the interval between inclusion and defect whose size and property are different is near.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.23 no.6 s.165
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• pp.968-978
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• 1999

The effective elastic properties of materials containing spherical inclusions were calculated by the elastic wave scattering theory. In the formulation additional scattering fields by the presence of random multiple scatterers that affects the effective properties were found by the single scattering approximation. In calculating the scattering fields the ensemble average on the displacements and strains inside the scatterer was found from the static approximation at long wavelength limit. The displacements were assumed to be equal to the incident field, while the strains were calculated by Eshelby's equivalent inclusion principle on the single inclusion problem. Four different models were considered and they reflected different degrees of multiple scattering effects based on the approximation introduced in the process of embedding the inclusion in the matrix. The expressions for the effective elastic constants were given in each model, and their relations to the results obtained from other scattering theory and elasticity theory were discussed. The theoretical predictions were compared with experimental results on the epoxy matrix composites containing tungsten particles of different sizes and volume fractions

• Conservation Science in Museum
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• v.10
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• pp.1-13
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• 2009

A part of the bronze bell from Goryeo (918-1392) in the collection of Buyeo National Museum was missing, and it was noted to retain corrosion products and burial accretions. Chemical analysis showed that the chemical composition of the bronze bell is Cu (74.18%), Sn (9.58%), Pb (15.77%), and very small amounts of As, Fe, Sb, Bi, and Ag. It was noted that the microstructure of the bronze bell was mainly made up of α phase and α+δ eutectoid phase, and gray (S) and black (Pb segregation) prevailed. Conservation treatment has been done for the preservation of this bronze bell.

• Composites Research
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• v.17 no.6
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• pp.8-13
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• 2004

A new three-dimensional model fur stress-strain relation of a porous shape memory alloy has been proposed, where Eshelby's equivalent inclusion method with Mori-Tanaka's mean field theory is used. The predicted stress-strain relations by the present model are compared and show good agreements with the experimental results for the Ni-Ti shape memory alloy with porosity of 12%. Unlike linear stress-strain relations during phase transformations by other models from the literature, the present model shows nonlinear stress-strain relation in the vicinity of martensite finish region.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.5
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• pp.1259-1268
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• 1995

The stress distribution around micro holes and the behavior of stress interaction between micro holes are considerd in the study. Several conclusions are extracted as follows : (1) The stress interaction varies with the distance e between micro holes. When the two micro holes are spaced in such a manner that theri two closest points are separated by a distance of micro hole radius (e=1), stress distribution is affected by a opposite micro hole in all the closest region. In addition, if two closest points are seperated by twice the distance of a micro hole radius (e=2), stress distribution is affected by a opposite micro hole in the region of -0.8.leq.x/r.leq.0.8 and the interaction effect can be neglected for e=4. (2)If the depth becomes larger than the radius, or the radius varies, the shape and magnitude of stress distribution around micro holes varies. (3) Hoop stress around a micro hole for the two dimensional configuration is larger than that of the three dimensional micro hole located on the surface of material for .theta. < 60.deg., but it is reversed for .theta > 60.deg.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.15 no.12 s.105
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• pp.1347-1354
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• 2005

The free vibration characteristics of Al cantilever square plates with a brass inclusion were analyzed experimentally and numerically The experimentally obtained natural frequencies and mode shapes were compared with the FEM analysis results. The impulse exciting method was used for experiment and ANSYS software package was used for FEM analysis. The natural frequencies obtained iron experiment and numerical analysis matched within $0\%$. It was found that the natural frequencies of the Al cantilever square plates with a brass inclusion decrease as the size of inclusion increases. For the third mode shape, comparing the nodal line of the Al plate and the Al plate with a inclusion, the mode shape showed the reversed quadratic curve. The natural frequencies of inclusion plate were decreased as the location of inclusion moves from the clamped edge to the tree edge.

• Proceedings of the KOR-BRONCHOESO Conference
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• 1987.05a
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• pp.15.1-15
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• 1987

1980년 1월 1일부터 1986년 12월 31일까지 7년 동안 가톨릭의과대학부속 성모병원 이비인후과에 내원한 식도 및 기도이물환자 246명을 분석하여 다음과 같은 결론을 얻었다. 1) 식도 및 기도이물의 빈도는 4.5 : 1이었다. 2) 식도이물의 종류별 빈도는 주화가 55.2%로 가장 많았고 다음이 골편, 식품류 등의 순이었다. 기도이물에서는 콩류가 57.8%로 가장 많았고 첨단 철물류와 식품류는 다음으로 많았다. 3) 식도이물의 56.7%가 5세이하이었으며 주화 및 원반류는 5세 이하가 대부분이었다. 기도이물의 88.9%가 5세이하이었으며 콩류에서는 96.2%가 5세 이하이었다. 4) 식도이물은 남자가 58.7%로 여자보다 많았으며 기도이물은 남자가 82%로 여자보다 많았다. 5) 식도이물의 개재부위는 제 1협착부에 78.1%로 가장 많았으며 식품류는 제 2협착부에서 높은 빈도를 보였다. 기도이물에서는 기관지가 84.4%로 가장 많았고 좌우기관지별 이물의 비는 1 : 1로 같았다. 6) 이물의 개재기간은 식도이물이 1일 이내가 72.6%, 기도이물이 1일 이내가 17.8%이었다. 7) 기도이물의 흉부 X-선 소견은 폐쇄성 폐기종과 폐염이 각각 37.8%, 26.7%로 가장 많았다.

• Proceedings of the KOR-BRONCHOESO Conference
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• 1995.04a
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• pp.93.1-93
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• 1995

저자들은 1985년 9월부터 1995년 2월까지 계명대학교 의과대학 이비인후과에 내원한 환자중 기도이물을 의심하여 환기형 기관지경술을 시행한 54례의 유소아 환자들을 대상으로 임상적 고찰을 하여 다음과 같은 결론을 얻었다.1) 기도이물을 의심한 환자 54례중 4세 이하가 49례(90.7%)로 대부분을 차지하였고, 남녀의 비는 3.5:1 이었다. 2) 이물개재 시간별 분포는 7일에서 30일 이내가 13례(24.0%)로 가장 많았고 다음이 2일에서 3일이내로 12례(22.2%)였다. 3) 기도이물의 증상으로는 기침(85.1%), 호흡곤란(38,9%), 고열(31.5%) 등의 순이었다. 4) 기도이물의 종류로는 식물성이 23례(67.6%)로 가장 많았고, 이중 땅콩이 19례였으며, 금속류, 플라스틱류 순이었다. 5) 이물이 있었던 34례중 흉부단순 X-선 소견상 이상소견을 나타낸 경우는 32례(94.1%)였으며, 이중 폐기종이 가장 많은 빈도를 보였고, 식물성이물은 전례에서 이상소견을 보였다. 6) 기도이물을 의심한 환자 54례중 이물이 없었던 20(37.0%)례 모두 흉부단순 X-선 소견상 이상소견을 나타내었고 이중 폐렴이 10례(50%)로 가장 많았고 무기폐, 페기종의 순이었다. 7) 이물의 개재부위는 주기관지 26례(우:14, 자:12), 기관 6례, 성문 2례의 순이었다.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2012.05a
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• pp.294-299
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• 2012

An investigation into the influence of ultrasonic standing wave on the structural behavior of propane/air premixed flame has been made to get a clue to the combustion reaction acceleration and combustion instability, as well. Visualization technique utilizing the Schlieren method was employed for the observation of structural variation of the premixed flame. The flame shape and propagation velocity were measured according to the variation of equivalence ratio. It was found that the standing wave distorted the flame front and expedited a transition to the flame with turbulent nature.

• Journal of the Korean Society of Propulsion Engineers
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• v.17 no.2
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• pp.16-23
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• 2013

An experimental study has been conducted to investigate the effects of equivalence ratio on the propagation characteristics of $CH_4$-air premixed flame intervened by an ultrasonic standing wave. A Schlieren photography was used for the flame structure visualization, and the flame propagation behavior was investigated in detail throughout the post-processing analysis. It is found that the structural variation of methane/air premixed flame caused by the intervention of ultrasonic standing wave give rise to the enhancement of combustion reaction and flame propagation velocity. Effectiveness of the standing wave on the flame velocity decreases as the equivalence ratio increases. Larger flame velocity with the standing wave becomes undistinguishable in a specific range of equivalence ratios.