• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.35 no.7
• /
• pp.655-660
• /
• 2007

A canard-leading edge flap deflection scheduling laws have been established to enhance the maneuverability of the canard type fighter class aircraft. These scheduling laws are the relation of canard-leading edge flap deflections and flight conditions to maximize the lift-drag ratio. For these purposes, the corrected supersonic panel method has been used to predict the lift-drag characteristics due to canard-leading edge flap deflections. In addition, the high speed wind tunnel test has been conducted with 1/20 scale model to validate the predicted scheduling laws. Good agreements have been obtained compared with the results of high speed wind tunnel test. Based on the results obtained from the experimental and numerical studies, the corrected supersonic panel method has shown to be useful to establish the canard-leading edge flap deflection scheduling law for the aerodynamic design of canard type fighter class aircraft.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
• /
• v.30 no.5
• /
• pp.477-484
• /
• 2012

Recently, as earthquake is more frequently taking place around the world due to diastrophism, the importance of diastrophism and disaster detection is becoming more important. In this study, to analyze the interpretation of seismic displacement by the Japanese earthquake in March, 2011, and monitor the diastrophism of plates in Japan and surrounding Eurasia, Pacific, and Philippines before and after the earthquake, the observational data from IGS observatories in Japan and Asian regions were processed by precise point positioning. The displacement was biggest in MIZU, which was the closest to the epicenter, and the earthquake-affected region was in inverse proportion to the distance from the epicenter. The result of calculating the diastrophism speed before and after the earthquake, based on precise point positioning of IGS observatories located in the 4 plates around Japan, showed that the displacement speed changed and different plates showed different results. The comparison with the plate fate model allowed to analyze the change in diastrophism by earthquake, and to understand the characteristics of the displacement of the plates around Japan. Later, a continuous diastrophism monitoring based on GPS is needed for earthquake prediction and diastrophism research, and the data gained by continuous GPS-based monitoring of diastrophism will be fully used as basic data for relevant research and earthquake disaster management.

• Journal of KSNVE
• /
• v.8 no.2
• /
• pp.260-266
• /
• 1998

According to the conventional method of analysis for the seismic sliding of equipment submerged in a pool, in general, only the initial condition of fluid gap is used to estimate the hydrodynamic effect between the two structures throughout the seismic analysis. This is based on the assumption of small displacement relative to the fluid gap thickness during earthquakes. In a narrow fluid gap condition, however, this method may lead to a result of unconservative side. Through example seismic analyses for equipment submerged in a pool of a building, in this paper, it is studied when and how much the sliding response can be underestimated. And method of updating the hydrodynamic effect in each step of time integration is proposed to avoid excessive error in estimation of peak sliding response in such a case.

• Computational Structural Engineering
• /
• v.9 no.4
• /
• pp.127-134
• /
• 1996

This paper is about a progressive fracture analysis of concrete by boundary element method. From both displacement boundary integral equation and traction boundary integral equation of solids with cracks, a boundary integral equation for crack problem is derived. For the analysis of progressive fracture of concrete, fracture process zone is modelled based on Dugdale-Barenblatt model with linear tension-softening curve. By using the boundary element modeling, the progressive fractures of concrete beam and compact-tension specimens with various loading conditions are analyzed and compared with experiments. The analysis results show that the technique in this paper can predict the maximum strength and the nonlinear behavior of concrete including post-peak behavior.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2003.03a
• /
• pp.797-804
• /
• 2003

본 연구에서는 진동대 실험을 실시하여 매립지에서 널리 사용되고 있는 지오멤브레인과 지오텍스타일 사이의 동적 접촉 마찰 특성을 살펴보았다. 연직응력, 진동 주파수, 건조/수침 상태의 영향에 대해서 평가하였으며, 또한 지오멤브레인과 지오텍스타일 사이의 상대적인 미끄러짐의 정도를 측정하였다. 실험 결과, 지오멤브레인과 지오텍스타일 사이를 통해 전달되는 한계 가속도(limited acceleration)가 있음을 확인할 수 있었으며, 이를 통해 지오멤브레인과 지오텍스타일 사이의 동적 접촉 마찰각을 산정할 수 있었다. 이러한 가속도는 수침상태의 경우 건조상태보다 더 작게 산정되었으며, 변위의 경우 수침상태에서 더 크게 발생함을 관찰하였다. 또한 실험조건에 따라 지오멤브레인과 지오텍스타일 사이에 발생하는 상대적인 미끄러짐의 정도가 다르게 측정되었다. 본 연구에서는 지오멤브레인과 지오텍스타일 사이의 slip equation을 제안하였으며, 이 식을 통해 주어진 가속도와 주파수에서 지오멤브레인과 지오텍스타일 사이를 따라 발생되는 최대 미끄러짐의 정도를 예측 가능하게 하였다.

• Proceedings of the Korean Institute of Surface Engineering Conference
• /
• 2016.11a
• /
• pp.201.1-201.1
• /
• 2016

전주된 Invar (Fe-35%Ni) 박판 위에 증착된 Cu 박막은 스퍼터 전력량이 증가할수록 증착속도가 증가하였다. Cu/Invar 박판이 Invar 박판보다 면저항 값이 34%로 작았다. Invar 박판 위에 Cu가 증착되면 최대자화와 투자율은 각각 40.3, 65.0 [%] 감소하였다. Cu 박막의 탄성하강강성도, 마찰계수, 피로한계는 각각 45, 0.130, 0.093 이었다. 동적 나노 압침법으로 얻은 Invaar/Cu 박막의 하중-시간-변위 곡선의 가장 큰 차이는 탄성하강강성도(elastic stiffness) 이었다. 미세경도와 나노경도의 실험적 관계식은 $Y[GPa]=9.18{\times}10^{-3}X[Hv]$ 이었다. 나노압침선단의 하중분포를 이차원 선형 및 비선형 유한요소해석을 통하여 1.0 [mN] 의 정적하중을 가한 Cu 박막은 486 [mN] 으로 예측되었다. 이는 표면탐침현미경으로 관찰한 압흔의 변형정도와 유사한 경향을 보였다.

• Magazine of the Korea Concrete Institute
• /
• v.9 no.6
• /
• pp.255-266
• /
• 1997

본 논문의 목적은 내진상세를 가진 철근콘크리트 골조의 비탄성 거동 예측에서 현재 사용되고 있는 해석적 방법이 가지는 신뢰성을 검토하고 실험에서 실측할 수 없었던 내부 힘의 분포 및 변화과정을 관찰하는 것이다. 이를 위하여 이미 실험이 수행된 2경간 2층 내진상세 모멘트-저항 철근콘크리트 평면골조(1)를 대상으로 ICARC 2D 프로그램(3)을 사용하여비탄성해석을 수행하였다. 해석결과가 실험결과에 최대한 일치하도록 관련 모델 변수들을 조절하였다. 이러한 해석결과가 실험결과와 어느 정도 일치하는 지 비교하였으며, 해석결과 얻어진 내부 힘의 발전과정을 관찰한결과 다음과 같은 결론에 도달하였다. (1)전체 횡력-횡변위 관계는 실험결과에 매우 유사하게 해석결과를 얻을 수 있다. (2)구조물의 힘의 분포 및 재분재 과정에 관련하여 해석은 구체적인 정보를 제사하였으며 실험결과 나타난 균열 및 변형결과와 대체로 일치한 소성힌지 발생과 파괴메카니즘을 나타내어 그 유용성을 입증하고 있다. (3)해석결과가 대체로 실험결가아 일치하나 국부거동과 관련하여 일부분 실제거동과 상당한 차이를 나타내어, 보다 정확한 모델을 개발할 필요성을 느낀다.

• The Journal of Engineering Geology
• /
• v.32 no.3
• /
• pp.351-361
• /
• 2022

Numerical analysis performed to predict the behavior of Ipseok-dae columnar joints in Mudeungsan National Park to understand their stability and movement. The numerical analysis technique, 3DEC, is based on the discrete element method that can analysis discontinuities. The analysis used data for material properties derived from laboratory tests, which found that average density was 2.68 kN/m³, average normal stiffness was 3.15 GPa/m, average shear stiffness was 1.00 GPa/m, average cohesion was 0.51 MPa, and the average friction angle was 33°. The Ipseok-dae columnar joints were modeled on the basis of the field survey data for 15 joints located between the observation platform and the hiking trail. The numerical analysis assessed the behavior of each columnar joint by interpreting the displacement of the edges of its upper and lower surfaces. The greatest maximum displacement was found in columnar joint No. 6, and the greatest minimum displacement was found in joint No. 11. Analyzing the movements of five discontinuities in joint No. 11 indicated that the maximum displacement occurred at the 2nd level. The other levels were ordered 5th, 4th, 1st, and 3rd in terms of subsequent greatest displacements. Considering the total displacement in the 15 studied joints, the Ipseok-dae columnar joints are judged to be stable. However, considering the cultural and historical value of Mudeungsan National Park, it is regarded that the currents slope stability should be maintained by monitoring the individual rock blocks of the joints.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.35 no.2
• /
• pp.165-170
• /
• 2007

During the conceptual design phase of a wing-body-canard type fighter class aircraft, as a method of maneuverability enhancement for an aircraft, effects of canard-leading edge flap scheduling have been studied. In this study, corrected supersonic panel method has been used to predict the drag polar characteristics due to canard-leading edge flap deflections in the high speed regime. Utilizing the predicted drag polar curves, the canard-leading edge flap scheduling laws have been established. These scheduling laws are the relation of canard-leading edge flap deflections and the flight conditions to maximize the lift-drag ratio. Based on the results obtained from the canard-leading edge flap scheduling, the present method has shown to be useful to enhance the maneuverability of wing-body-canard type fighter class aircraft.

• Journal of the Korean Geotechnical Society
• /
• v.20 no.8
• /
• pp.167-180
• /
• 2004

In this study finite element analysis using hyperbolic model was performed to predict the characteristics of stress-strain behaviour on concrete face earth dam (CFED : a tentative name) raised with coarse-grained materials corresponding to the face slab bedding zone of concrete face rockfill dam (CFRD). The results of finite element analysis were compared with field monitoring data, and the comparison showed a good agreement. And, the analysis results including locus of maximum displacement, maximum stress, stress concentration, and irregular load transfer would be used to devise rational field monitoring schemes for construction management and quality control during construction of CFED.