• Korean Institute of Interior Design Journal
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• no.38
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• pp.48-56
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• 2003

This study is purposed to find the transition of the perspective connected with visual modality. The perspective based on Greek optics and euclidean geometry and rediscovered in Renaissance represents the object according to the particular moment and the point of view, is a principal fact which affect architecture, the form of a city and the spatial organization and symbolizes an ideal of the times. It embodied perception which treats the space rationally on the basis of realism and became visual modality based on the separation of the seeing subject and the world of the object. The point of view became one with the vanishing point which made up the shape and after Renaissance for four hundred years a straight line, a right angle and a circle got to be favorite geometrical choices in architecture. A fixed point of view of the subject is getting to change and break up fundamentally by the new visual technologies of the modem times.

• International Journal of CAD/CAM
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• v.5 no.1
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• pp.19-27
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• 2005

As three-dimensional range scanners make large point clouds a more common initial representation of real world objects, a need arises for algorithms that can efficiently process point sets. In this paper, we present a method for extracting smooth surfaces from dense point clouds. Given an unorganized set of points in space as input, our algorithm first uses principal component analysis to estimate the surface variation at each point. After defining conditions for determining the geometric compatibility of a point and a surface, we examine the points in order of increasing surface variation to find points whose neighborhoods can be closely approximated by a single surface. These neighborhoods become seed regions for region growing. The region growing step clusters points that are geometrically compatible with the approximating surface and refines the surface as the region grows to obtain the best approximation of the largest number of points. When no more points can be added to a region, the algorithm stores the extracted surface. Our algorithm works quickly with little user interaction and requires a fraction of the memory needed for a standard mesh data structure. To demonstrate its usefulness, we show results on large point clouds acquired from real-world objects.

• Korean Journal of Acupuncture
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• v.31 no.2
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• pp.49-55
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• 2014

Objectives : Five transport points are often used in acupuncture treatment. However, there is no clear explanation about the reason why the five transport points are matched five phases in this manner. Therefore, we reviewed the literatures and theses about the principal of matching and researched a new way to understand the reason. Methods : We found 8 theses and 3 literatures related to the matching of five transport points to five phases by searching the web sites. And, we reviewed the principal of matching and researched another new way to understand the reason why they are matched so. Results and Conclusions : In the viewpoint of the natural state and function of five phases, the start points arising in yin- and yang-meridian are matched to wood and metal respectively. Therefore, well point matches the wood and metal in yin- and yang-meridian respectively. And by following the flow of five transport points, the other points match with fire, earth, metal, water in yin-meridian and water, wood, fire, and earth in yang-meridian.

• Journal of Korean Ophthalmic Optics Society
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• v.6 no.2
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• pp.11-16
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• 2001

The polariscope to measure :he stress in lens was made up quarter-wave plate polarizer and we analyzed two components of light's wave $E_1$ and $E_2$ following the steps. It is clear that the principal-stress difference ${\sigma}_1-{\sigma}_2$ can be determined in 2-D model if fringe order N is measured each point in sample moreover. the optical axes of sample coincide with the principal-stress directions. The birefringence acted to a light wave and a phase retardation were in proportioned to the principal-stressed difference (${\sigma}_1-{\sigma}_2$) and the intensity of final light wave was proportioned to $sin^2({\Delta}/2)$, when ${\Delta}/2=n^{\pi}$ (n=0, 1, 2, ...) and the extinction occurs. As a experimental result, the extinction band shifted owing to a magnitude of lens' external stress.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2006.04a
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• pp.1001-1008
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• 2006

The main objective of this paper is to compare economical effectiveness of typical methods for checking stability in principal components of steel cable-stayed bridges. Elastic and inelastic buckling analyses are carried out for frame-like numerical models of cable-stayed bridges. The axial-flexural interaction equations prescribed in AASHTO Allowable Stress Design (ASD) and AASHTO Load and Resistance Factor Design (LRFD) are used in order to check the stability of principal components. Parametric studies are performed for numerical models which have the center span length of 300m, 600m, 900m and l200m with different girder depths. Peak values of the interaction equations are calculated at the intersection point between girders and towers. These peak values are considered as a major factor to design of principal components of cable-stayed bridges. As a result, more economical design for girders and towers can be feasible using the inelastic buckling analysis. In addition, LRFD codes are more economical about 20% on the average than ASD codes for all numerical models of cable-stayed bridges.

• Earthquakes and Structures
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• v.7 no.5
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• pp.647-665
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• 2014

Squat reinforced concrete walls require enough shear strength in order to promote flexural yielding, which creates the need for designers of an accurate method for strength prediction. In many cases, especially for existing buildings, strength estimates might be insufficient when more accurate analyses are needed, such as pushover analysis. In this case, estimates of load versus displacement are required for building modeling. A model is developed that predicts the shear load versus shear deformation of squat reinforced concrete walls by means of a panel formulation. In order to provide a simple, design-oriented tool, the formulation considers the wall as a single element, which presents an average strain and stress field for the entire wall. Simple material constitutive laws for concrete and steel are used. The developed models can be divided into two categories: (i) rotating-angle and (ii) fixed-angle models. In the first case, the principal stress/strain direction rotates for each drift increment. This situation is addressed by prescribing the average normal strain of the panel. The formation of a crack, which can be interpreted as a fixed principal strain direction is imposed on the second formulation via calibration of the principal stress/strain direction obtained from the rotating-angle model at a cracking stage. Two alternatives are selected for the cracking point: fcr and 0.5fcr (post-peak). In terms of shear capacity, the model results are compared with an experimental database indicating that the fixed-angle models yield good results. The overall response (load-displacement) is also reasonable well predicted for specimens with diagonal compression failure.

• Environmental Engineering Research
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• v.19 no.3
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• pp.197-203
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• 2014

This study estimated spatial and seasonal variation of water quality to understand characteristics of Nakdong river basin, Korea. All together 11 parameters (discharge, water temperature, dissolved oxygen, 5-day biochemical oxygen demand, chemical oxygen demand, pH, suspended solids, electrical conductivity, total nitrogen, total phosphorus, and total organic carbon) at 22 different sites for the period of 2003-2011 were analyzed using multivariate statistical techniques (cluster analysis, principal component analysis and factor analysis). Hierarchical cluster analysis grouped whole river basin into three zones, i.e., relatively less polluted (LP), medium polluted (MP) and highly polluted (HP) based on similarity of water quality characteristics. The results of factor analysis/principal component analysis explained up to 83.0%, 81.7% and 82.7% of total variance in water quality data of LP, MP, and HP zones, respectively. The rotated components of PCA obtained from factor analysis indicate that the parameters responsible for water quality variations were mainly related to discharge and total pollution loads (non-point pollution source) in LP, MP and HP areas; organic and nutrient pollution in LP and HP zones; and temperature, DO and TN in LP zone. This study demonstrates the usefulness of multivariate statistical techniques for analysis and interpretation of multi-parameter, multi-location and multi-year data sets.

• Structural Monitoring and Maintenance
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• v.9 no.1
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• pp.59-80
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• 2022

In the present study, the objective is to detect the structural damages using the responses obtained from the sensors at the optimal location under uncertainty conditions. Reducing the error rate in damage detection process due to responses' noise is an important goal in this study. In the proposed algorithm for optimal sensor placement, the noise of responses recorded from the sensors is initially reduced using the principal component analysis. Afterward, the optimal sensor placement is obtained by the damage detection equation based sensitivity analysis. The sensors are placed on degrees of freedom corresponding to the minimum error rate in structural damage detection through this procedure. The efficiency of the proposed method is studied on a truss bridge, a space dome, a double-layer grid as well as a three-story experimental frame structure and the results are compared. Moreover, the performance of the suggested method is compared with three other algorithms of Average Driving Point Residue (ADPR), Effective Independence (EI) method, and a mass weighting version of EI. In the examples, young's modulus, density, and cross-sectional areas of the elements are considered as uncertainty parameters. Ultimately, the results have demonstrated that the presented algorithm under uncertainty conditions represents a high accuracy to obtain the optimal sensor placement in the structures.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.31 no.2
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• pp.173-178
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• 1986

Principal component analysis was used for ana1zing growth data to know the relationship between growth characteristics and yield as well as its components. The first principal component accounted for average time of the specific leaf area sampled, leaf area index, and dry weight, and the second component for the position of the changing point of growth characteristics. The component scores were more affected by the nitrogen level than variety. Yield were affected by fertility ratio and number of spikelets per hill which have close relation with the component score of leaf area index and dry weight per hill.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2004.04a
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• pp.285-292
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• 2004

The objective of this paper is to develop a simplified method to determine yield line patterns of reinforced concrete floor slabs based on the elastic fields. Unlike other methods mainly focused on the plasticity theory, this paper emphasizes the elastic fields, especially principal moments and maximum shears and shows a link between elasticity field and yield line patterns. General criteria on both positive and negative yield lines are suggested in terms of principal moments and maximum shear forces. The proposed method can predict starting point (or regions) of yielding and the further development of yield lines on whole structures. The yield line patterns determined by the proposed method are shown to be coincident with the classical yield line theory. Furthermore, orthotropy in reinforced concrete slab is investigated and yield line patterns for different type of flat slab with non-isotropic strip are studied broadly.