• 한국자기학회지
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• 제7권6호
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• pp.314-320
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• 1997

폴리에스터 film 위에 자성도료를 도포 후 자성체의 배향 거동을 살펴보았다. static orientation 처리하여 평가한 결과 자성도료가 도포된 film이 배향자석을 통과할 때 배향자석의 입구측과 출구측에서 배향성이 최대로 나타나나 출구측이 약간 낮게 나타났으며 배향자석의 출구를 지나면서 static energy의 감소와 entropy의 증가에 의하여 도막의 건조과정 중 배향성은 서서히 감소되다가 완전히 건조되면서 일정한 수준으로 유지되었다. 그리고 film의 중심부보다 양쪽의 edge 부위에서의 배향성은 떨어지는데 그 원인은 배향자석의 형태에 기인하는 것으로 생각된다. Dynamic orientation 처리하여 평가한 결과 자기 tape에서 자성도막의 배향성이 향상됨에 따라 전 대역에서의 출력 특성은 향상되었으며 건조 조건에 따라서도 tape의 배향성이 변하였다. 따라서 자기 tape의 출력특성을 향상시키기 위하여는 배향자석의 설계 및 자성도료의 건조 조건 등의 검토가 필요하다고 생각한다.

• 한국해양공학회지
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• 제12권2호통권28호
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• pp.1-21
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• 1998

In this paper, a non-conforming 3-D 8-node solid element(MQM10) has beets applied to the analyses of static and dynamic bending problems of laminated composite plates The QM10 element exhibits stiffer bending stiffness which is caused by the reduction of degree of freedom from Q11 element. As an effective way to correct the relative stiffness stiffening phenomenon the modification of Gauss sampling points for composite plates is proposed. The quantity of modification is a function of material properties. Also, another two modified equations are obtained, one is modification for stress, and the other is modification of coefficient of shear modulus in free vibration. It is noted that MQM10 element can analyse the static and free vibration problems of various 3-dimensional composite plates composed of unidirectional laminae, woven laminae or braided laminae. The results of MQM10 element are in good agreement with those of 20-node element.

• 감성과학
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• 제10권1호
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• pp.113-125
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• 2007

본 연구에서는 동영상 자극과 정지 영상 자극을 사용하여 얼굴 표정의 영역(얼굴 전체/눈 영역/입 영역)에 따른 정서 상태 전달 효과를 알아보고자 하였다. 동영상 자극은 7초 동안 제시되었으며, 실험 1에서는 12개의 기본 정서에 대한 얼굴 표정 제시 유형과 제시 영역에 따른 정서 인식 효과를, 실험 2에서는 12개의 복합 정서에 대한 얼굴 표정 제시 유형과 제시 영역에 따른 정서 인식 효과를 살펴보았다. 실험 결과, 동영상 조건이 정지 영상 조건보다 더 높은 정서 인식 효과를 보였으며, 입 영역과 비교하였을 때 동영상에서의 눈 영역이 정지 영상 보다 더 큰 효과를 보여 눈의 움직임이 정서 인식에 중요할 것임을 시사하였다. 이는 기본 정서 뿐 아니라 복합 정서에서도 어느 정도 관찰될 수 있는 결과였다. 그럼에도 불구하고 정서의 종류에 따라 동영상의 효과가 달라질 수 있기 때문에 개별 정서별 분석이 필요하며, 또한, 얼굴의 특정 영역에 따라서도 상대적으로 잘 나타나는 정서 특성이 다를 수 있음을 사사해 준다.

• 한국지반환경공학회 논문집
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• 제10권3호
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• pp.5-12
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• 2009

본 연구는 발전소의 적치장에서 채취한 석탄회의 정적 및 동적 강도를 제시하였다. 석탄회는 주로 저회로 이루어져 있으며 정적 및 동적 강도를 평가하기 위하여 NGI형 단순전단시험, 반복단순전단시험 및 직접전단시험을 수행하였으며, 이러한 시험으로부터의 강도를 모래의 강도와 비교하였다. 본 연구에 사용된 석탄회 속에 있는 저회는 입도분포에 의하면 모래로 분류되었으며 모래보다 높은 강도 특성을 보였다. 석탄회를 토목공사에 활용되기 위해서 사질토와 석탄회를 50:50의 비율로 배치플랜트에서 섞어 사용하는 것은 사질토층과 석탄회층을 교대로 층별 시공하는 것보다 비효율적이다. 혼합시공과 층별시공을 모사하기 위하여 모래와 석탄회가 50:50으로 조성된 시료를 준비하였다. 시험결과 혼합에 의한 시료가 층별시료보다 약간 큰 정적 및 동적 강도를 나타내었다. 높은 강도는 주로 저회의 모난 입자로부터 기인된 것으로 보인다. 혼합시료에서 액상화시의 반복응력비는 반복횟수가 증가함에 따라 층별시료보다 급격히 감소하였다.

• 소성∙가공
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• 제14권6호
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• pp.559-564
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• 2005

INCONEL 718, nickel based superalloy, has good formability, high strength, excellent corrosion resistance and mechanical properties at high temperature. Owing to theses attractive properties, it is utilized in applications such as combustion system, turbine engines and nuclear reactors. In such applications, components are typically required to be tolerant of high stress impact loading. This may cause material degradation and lead to catastrophic failure during service operation. Accurate understanding of material's mechanical properties with various strain rates is required in order to guarantee the reliability of structural parts made of INCONEL 718. This paper is concerned with the dynamic material properties of the INCONEL 718 at various strain rates. The dynamic response of the INCONEL 718 at the intermediate strain rate is obtained from the high speed tensile test and at the high strain rate is from the split Hopkinson pressure bar test. The effect of the strain rate on dynamic flow stress, work hardening characteristics, strain rate sensitivity and elongation to the failure is evaluated with the experimental results. Experimental results from both the quasi-static and the high strain rate up to 5000/sec are interpolated in order to construct the Johnson-Cook model as the constitutive relation that should be applied to simulate and design the structural parts made of rNCONEL 718.

• 한국지반공학회논문집
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• 제26권6호
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• pp.71-85
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• 2010

터널의 동적 지진해석은 실무에서 널리 수행되고 있다. 동적해석은 하부 및 측면 경계 조건, Deconvolution, 구성모형, 동적 물성치 등을 적용 또는 결정하기 어려워서 해석 수행 시 주의해야 하지만 이에 대한 명확한 가이드라인이 제시된 바 없다. 또한 많은 경우에는 터널의 동적해석 자체가 필요없지만 이에 대한 필요성과 정적해석과의 차이에 대한 이해 없이 무분별하게 사용되고 있는 실정이다. 본 논문에서는 일차적으로 2차원 동적 해석을 올바르게 수행하기 위한 가이드라인을 제시하였다. 이차적으로는 제시된 가이드라인을 준수한 2차원 동적해석을 수행하였으며 해석결과를 응답변위법을 비교하였다. 응답변위법과 동적해석을 비교한 결과, 두 해석기법간의 차이는 크지 않은 것으로 나타났다. 즉, 터널 갱구부, 초연약지반, 또는 공간적 변이성을 고려해야 하는 경우를 제외하고는 터널의 횡방향 지진해석은 응답변위법으로도 충분히 정확하게 터널의 응답을 예측할 수 있을 것으로 판단된다.

• Journal of the Korean Wood Science and Technology
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• 제16권3호
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• pp.48-64
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• 1988

This study was carried out to investigate the free vibrational properties of traditional and replaceable species for sounding board, using piezoelectrical accelerometer and signal analyzer. In the study, the frequency equations of free-free beam carrying a concentrated mass in the transverse vibration and of free-mass beam in the longitudinal vibration were used. The results obtained were as follows. 1. Average values of dynamic modulus of rigidity of Korean commercial species measured were as follows. Paulownia tomatosa (Thunb.) Steudel: $5.590\times10^9\;dyne/cm^2$ Tilia amurensis Rupr.: $5.414\times10^9\;dyne/cm^2$ Macckia amurensis Rupr.: $10.044\times10^9\;dyne/cm^2$ Fraxinus mandshurica Rupr.: $8.876\times10^9\;dyne/cm^2$ Ulmus davidiana var.japonica Nakai: $8.677\times10^9\;dyne/cm^2$ Pinus rigida Miller: $6.33\times10^9\;dyne/cm^2$ Fraxinus rhynchophylla Hance: $4.666\times10^9\;dyne/cm^2$ 2. The ratio of dynamic transverse Young's modulus to dynamic modulus of rigidity, $E_T/G_{LT}$, was 24.922 for Fraxinus rhynchophylla Hance, which was the highest, 7.317 for Paulownia tomentosa (Thunb.) Steudel, which was the lowest among Korean commercial species measured. 3. The value of longitudinal dynamic Young's modulus was about 3.7% and 19.8%, respectively, higher than those of transverse dynamic and static Young's modulus. The value of transverse dynamic Young's modulus was about 15.5% higher than that of static Young's modulus. 4. Predicted value of MOR in terms of correlation coefficient by transverse dynamic Young's modulus was slightly higher than that of static Young's modulus, but no significance was found out. 5. Transverse dynamic Youne's modulus was $(2.002\pm0.288)\times10^{11}\;dyne/cm^2$ for Fraxinus mandshurlca Rupr., which was the highest, $(0.601\pm0.100)\times10^{11}\;dyne/cm^2$ for Paulownia tomentosa (Thunb.) Steudel, which was the lowest among Korean commercial species measured. The sound velocity of sitka spruce was 5,685 m/sec, which was the highest. 6. Internal friction of Paulownia tomentosa (Thunb.) Steudel was shown the lowest value among Korean commercial species, $(8.795\pm1.795)\times10^{-3}$, but was higher than that of sitka spruce, $(7.331\pm0.991)\times10^{-3}$. Internal friction was shown negative correlation with density and dynamic Young's modulus, respectively. 7. K value was affected largely by internal friction and was the highest, $2.225\times10^8$ for Paulownia tomentosa (Thunb.) Steudel and was the lowest, $0.550\times10^8$ for Fraxinus rhynchophylla Hance. K value of Paulownia tomentosa (Thunb.) Steudel was higher than that of sitka spruce and K values of melapi and cottonwood, which have been considered to be replaceable species with sitka spruce in the piano industry, were lower than those of Paulownia tomentosa (Thunb.) Steudel and mill amurensis Rupr.

• 한국항공운항학회지
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• 제18권4호
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• pp.44-50
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• 2010

Structural vibration is a significant problem in many multi-part or multi-component assemblies. In aircraft industry, structures are composed of various fasteners, such as bolts, snap, hinge, weld or other fastener or connector (collectively "fasteners"). Due to these, prediction and design involving dynamic characteristics is quite complicated. However, the current state of the art does not provide an analytical tool to effectively predict structure's dynamic characteristics, because consideration of structural uncertainties (i.e. material properties, geometric tolerance, dimensional tolerance, environment and so on) is difficult and very small fasteners in the structure cause a huge amount of analysis time to predict dynamic characteristics using the FEM (finite element method). In this study, to resolve the current state of the art, a new approach is proposed using the FEM and probabilistic analysis. Firstly, equivalent elements are developed using simple element (e.g. bar, beam, mass) to replace fasteners' finite element model. Developed equivalent elements enable to explain static behavior and dynamic behavior of the structure. Secondly, probabilistic analysis is applied to evaluate the PDF (probability density function) of dynamic characteristics due to tolerance, material properties and so on. MCS (Monte-Carlo simulation) is employed for this. Proposed methodology offers efficiency of dynamic analysis and reality of the field as well. Simple plates joined by fasteners are taken as an example to illustrate the proposed method.

• Elastomers and Composites
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• 제30권2호
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• pp.112-121
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• 1995

The physical properties of rubber compounds containing silica and siliane coupling agent in order to replace the carbon black and prepare for environmental regulation showed improved dynamic properties(rebound, heat build-up, $60^{\circ}C\;tan\;{\delta}$), but the abrasion resistance did not improve compared with the compounds containing carbon black. Also, curing retardation because of coherent structure of silica improved by the addition of DEG, but the mixing step change of activators did not so much improve the static and dynamic properties of the compounds containing high synthetic rubber, the status of mixing and dispersion showed that the compounds containing carbon black was much better than the compounds containing silica by TEM investigation.

• 한국정밀공학회지
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• 제18권5호
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• pp.98-104
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• 2001

A dynamic fracture toughness test method with a chevron notched ceramic specimens is proposed. The notch angles of the chevron specimens were 90, 100$^{\circ}$and 110$^{\circ}$. Finite element analysis(FEA) were done to determine the geometrical properties of chevron-notch specimens according to notch angles. The static fracture toughness of the chevron notched alumina specimen was 3.8MP$\alpha$√m similar to that of the general fracture specimen with a precrack. Dynamic fracture toughness was 4.5 MP$\alpha$√m slightly higher than the static one. These research showed the possibility of the split Hopkinson pressure bar test method using the newly proposed chevron notched specimens to get the dynamic fracture toughness of extremely brittle materials such as ceramics.