• Proceedings of the KSME Conference
• /
• 2003.04a
• /
• pp.774-779
• /
• 2003

Arc-shaped line array slits have been used for the laser generation of focused Lamb waves. The spatially expanded Nd:YAG pulse laser was illuminated through the arc-shaped line array slit on the surface of a sample plate to generate the Lamb waves of the same pattern as the slit. Then the generated Lamb waves were focused at the point of which distance from the slit position is dependent on the curvature of slit arc. The proposed method showed better spatial resolution than the conventional linear array slit in the detection of laser machined linear defect and drill machined circular defect on aluminum plates of 1mm thickness.

• Proceeding of KASS Symposium
• /
• 2005.05a
• /
• pp.125-132
• /
• 2005

Membrane structures, a kind of lightweight soft structural system, are used for spatial structures. The material property of the membrane has strong axial stiffness, but little bending stiffness. The design procedure of membrane structures are needed to do shape finding, stress-deformation analysis and cutting pattern generation. In shape finding, membrane structures are unstable structures initially. These soft structures need to be introduced initial stresses because of its initial unstable state, and it happens large deformation phenomenon. And also there are highly varied in their size, curvature and material stiffness. So, the approximation inherent in cutting pattern generation methods is quite different. Therefore, in this study, to find the structural shape after large deformation caused by Initial stress, we need the shape analysis considering geometric nonlinear ten And the geodesic line on surface of initial equilibrium shape and the cutting pattern generation using the geodesic line is introduced.

• Journal of Korean Association for Spatial Structures
• /
• v.15 no.4
• /
• pp.49-56
• /
• 2015

The roof grid of single-layer space frame structure, for Energy Core of Incheon Airport Second Terminal, is very simple and aesthetic, but it is apt to buckle under external force because of mild curvature and complex shape. The object of this study is to estimate the stability of single-layer space frame structures for Energy Core of Incheon Airport Second Terminal with the analytical conditions of structural design. The results show that the buckling load of model(pin-pin, uniform load, rigid joint), that is, the most similar model to the analytical conditions of structural design. was $10.7kN/m^2$.

• International journal of advanced smart convergence
• /
• v.4 no.2
• /
• pp.163-169
• /
• 2015

This study proposes a sports simulation device with various harmonics generation. The proposed system is composed of 6 degrees of freedom simulator devices and three types of sports simulation such as walking, snowboard, and jet-ski. In this research, every joint movement is designed with a crank-and-slider mechanism, which is efficient for generating continuous curvature smoothly. Contrary to the conventional spatial simulator with linear actuators, harmonics generation and its spatial combinations become the crucial issue in this research. The harmonic pattern in each joint is modelled for generating smooth curvatures that are also superposed for achieving overall motions. In addition, the targeted motions of sports simulations have different physical factors of periodic gait motion, frictionless surface, and buoyant effects, which are respectively designed by integrating three dimensional graphics information.

• Transactions of the Society of Information Storage Systems
• /
• v.10 no.2
• /
• pp.55-60
• /
• 2014

Laser projector has many advantages of high brightness, high resolution and small size, but the huge drawback of image degradation called speckle which generated by coherence of laser and roughness of surface interrupts their general use. There are many methods to reduce speckle pattern, but they need effective optical systems to realize display to the far field with huge volume. We designed speckle reduction element by using microlens with controlled curvature to reduce spatial coherence. Vibration element was also applied to reduce temporal coherence which considered response time of eye. Designed element was fabricated by simple reflow method and imprinting method. From the results, the fabricated element performed 48.33% of speckle reduction efficiency and 41.29% of optical efficiency with a single doublet lens.

• Proceedings of the KSRS Conference
• /
• 2003.11a
• /
• pp.135-137
• /
• 2003

The purpose of this preliminary study is the applied to geology using the Landsat TM satellite image of the Tanggung area of southern part of the Bandung, Indonesia to provide basic information for geological survey. For this, topography, geology and satellite image were constructed to spatial database. Digital elevation, slope, aspect, curvature, hill shade of topography were calculated from the topographic database and lithology was imported from the geological database. Lineament, lineament density, and NDVI were extracted the Landsat TM satellite image. The results showed the close relationship between geology and terrain and satellite image. Each sedimentary rock seldom corresponds with geology and analyses of topography but as a whole for sedimentary rocks coincide with them. Tuff and volcanic breccia in the volcanic rocks correspond with the result of terrain analyses. Talus deposits is well matched with the analyses of opography/satellite image.

• Proceedings of the Korean Society of Computer Information Conference
• /
• 2024.01a
• /
• pp.23-26
• /
• 2024

본 논문에서는 그래프 구조의 데이터에서 각 노드의 신호를 예측하는 연구를 진행하였다. 이를 위해 분석하고자 하는 그래프에 대해 연결 관계를 기반으로 각 노드에 비-유클리드 공간 상에서의 좌표를 부여하여 그래프의 공간적 임베딩을 얻은 뒤, 각 노드의 공간적 임베딩을 입력으로 받고 해당 노드의 신호를 예측하는 그래프 암시적 신경 표현 모델을 제안 하였다. 제안된 모델의 검증을 위해 네트워크형 데이터와 3차원 메시 데이터 두 종류의 그래프 데이터에 대하여 신호 학습, 신호 예측 및 메시 데이터의 초해상도 과정 실험들을 진행하였다. 전반적으로 기존의 그래프 암시적 신경 표현 모델과 비교하였을 때 비슷하거나 더 우수한 성능을 보였으며, 특히 네트워크형 그래프 데이터 신호 예측 실험에서 큰 성능 향상을 보였다.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.7 no.4
• /
• pp.1-13
• /
• 2003

For spatial free vibration of non-symmetric thin-walled curved beams with shear deformation, an improved formulation is proposed in the present study. The elastic strain and the kinetic energies are first derived by considering constant curvature and shear deformation effects due to shear forces and restrained warping torsion. Next equilibrium equations and force-deformation relations are obtained using a stationary condition of total potential energy. And the finite element procedures are developed by using isoparametric curved beam element with arbitray thin-walled sections. Particularly not only shear deformation and thickness-curvature effects on vibration behaviors of curved beams but also mode transition and crossover phenomena with change in curvatures of beams are parametrically investigated. In order to illustrate the accuracy and the reliability of this study, various numerical solutions for spatial free vibration are compared with results by available references and ABAQUS's shell element.

• Journal of The Geomorphological Association of Korea
• /
• v.25 no.2
• /
• pp.1-14
• /
• 2018

The main objective of this paper is to classify properties of the locational environment for each debris type by calculating likelihood ratio based on the correlation between the distributions for each type of debris landform. A total of 8 thematic maps, like as elevation, slope, aspect, curvature, topographic wetness index (TWI), soil drainage, geology, and landcover including with GIS spatial information generally used in this type of debris landform analysis. The results of this study showed that the block stream had a high likelihood ratio compared to talus in areas with relatively high elevation; and concerning slope, the block stream had a high likelihood ratio in a relatively low region than talus. Concerning aspect, a clear correlation could not be analyzed for each debristype, and concerning curvature, the block stream displayed a developed slope on the more concave valley than the talus. Analysis concerning TWI, the block stream displayed a higher likelihood ratio in wider sections than talus, and concerning soil drainage, the talus and block stream both displayed a high likelihood ratio in regions with well-drained soil. The talus displayed a high likelihood ratio in the order of metamorphic rocks, sedimentary rocks, and granite, while the block stream displayed a high likelihood ratio in the order of volcanic rocks, granite, and sedimentary rocks. In addition, concerning landcover, the likelihood ratio had the most concentrated distributed compared to natural bare land only concerning talus. Based on the likelihood ratio result, it can be used as basic data for extracting the possible areas of distribution for each debris type through the GIS spatial integration method.

• Proceedings of the KSRS Conference
• /
• 2004.10a
• /
• pp.302-305
• /
• 2004

The aim of this study is to apply and crossvalidate a spatial logistic multiple-regression model at Boun, Korea, using a Geographic Information System (GIS). Landslide locations in the Boun area were identified by interpretation of aerial photographs and field surveys. Maps of the topography, soil type, forest cover, geology, and land-use were constructed from a spatial database. The factors that influence landslide occurrence, such as slope, aspect, and curvature of topography, were calculated from the topographic database. Texture, material, drainage, and effective soil thickness were extracted from the soil database, and type, diameter, and density of forest were extracted from the forest database. Lithology was extracted from the geological database and land-use was classified from the Landsat TM image satellite image. Landslide susceptibility was analyzed using landslide-occurrence factors by logistic multiple-regression methods. For validation and cross-validation, the result of the analysis was applied both to the study area, Boun, and another area, Youngin, Korea. The validation and cross-validation results showed satisfactory agreement between the susceptibility map and the existing data with respect to landslide locations. The GIS was used to analyze the vast amount of data efficiently, and statistical programs were used to maintain specificity and accuracy.