• Current Optics and Photonics
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• v.5 no.3
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• pp.322-328
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• 2021

In this paper, a pretreatment method for a matrix in convex optimization is proposed to optimize the spectral reconstruction process of a disordered dispersion spectrometer. Unlike the reconstruction process of traditional spectrometers using Fourier transforms, the reconstruction process of disordered dispersion spectrometers involves solving a large-scale matrix equation. However, since the matrices in the matrix equation are obtained through measurement, they contain uncertainties due to out of band signals, background noise, rounding errors, temperature variations and so on. It is difficult to solve such a matrix equation by using ordinary nonstationary iterative methods, owing to instability problems. Although the smoothing Tikhonov regularization approach has the ability to approximatively solve the matrix equation and reconstruct most simple spectral shapes, it still suffers the limitations of reconstructing complex and irregular spectral shapes that are commonly used to distinguish different elements of detected targets with mixed substances by characteristic spectral peaks. Therefore, we propose a special pretreatment method for a matrix in convex optimization, which has been proved to be useful for reducing the condition number of matrices in the equation. In comparison with the reconstructed spectra gotten by the previous ordinary iterative method, the spectra obtained by the pretreatment method show obvious accuracy.

• The Research Journal of the Costume Culture
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• v.30 no.1
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• pp.1-15
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• 2022

This study aims to investigate the socio-cultural background of Poulaines, which influenced fashion and contemporary shoe design. Analyzing the characteristics of the Poulaines provided basic data for different shoes. The study method utilized previous studies to explore the concept and characteristics of Poulaines. In the empirical analysis, shoe design data mainly came from collections that illustrate formative elements of contemporary shoe design from the 2010 S/S season to the 2020 S/S season. A total of 709 photo materials were collected and analyzed. The results showed that the morphological characteristics of Poulaines were exaggerated to symbolize classes of the past and sexual expression. The expanding structure was divided into the fore nose, heel, and top-line and featured a design that expressed the formative beauty of Poulaines. Additionally, the decorative desire to represent wealth and class using various materials introduced new designs into contemporary shoe designs while showing extreme decorativeness through over-trimming and color contrast. Furthermore, the heterogeneous characteristics that come from the change and harmony of the shoes' body and heel that deviated from the existing shoe shapes were classified into the dissolution of shapes and mixing and matching. Thus, they broke the monotonous silhouette of shoes and gave variety delicately.

• Steel and Composite Structures
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• v.43 no.6
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• pp.759-772
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• 2022

Concrete-filled double skinned steel tubular (CFDST) columns have been used to construct modern structures such as tall buildings and bridges as well as infrastructures as they provide better, lesser weight, and greater stiffness in structural performance than conventional reinforced concrete or steel members. Different shapes of CFDST columns may be needed to satisfy the architectural and aesthetic criteria. In the study, three-dimensional FE simulations of circular and elliptical CFDST columns under axial compression were developed and verified through the experimental test data from the perspectives of full load-displacement histories, ultimate axial strengths, and failure modes. The verified FE models were used to investigate and compare the structural performance of CFDST columns with circular and elliptical cross-section shapes by evaluating the overall load-deformation curves, interaction stress-deformation responses, and composite actions of the column. At last, the accuracy of available design models in predicting the ultimate axial strengths of CFST columns were investigated. Research results showed that circular and elliptical CFDST column behaviors were generally similar. The overall structural performance of circular CFDST columns was relatively improved compared to the elliptical CFDST column.

• Journal of Korean Association for Spatial Structures
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• v.21 no.4
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• pp.23-30
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• 2021

In this paper, a twisted shape structure with an elevation form favorable to the resistance of vibration caused by wind loads is selected from among the forms of high-rise buildings. The analytical model is a square, triangular, and hexagonal plane with a plane rotation angle of one degree from 0 to 3 degrees per each story. As a result of the analysis, as the twist angle increased, story drift ratio is increased. Responses with different eccentricity rates were shown by analytical models. Therefore planar shapes designed symmetrically to the horizontal axis of X and Y are considered advantageous for eccentricity and torsion deformation. In the case of the bending moment of the column, the response was amplified in the column supporting the base floor, the roof floor, the floor in which the cross-section of the vertical member changes, and the floor having the same number of nodes as the base floor. Finally, the axial force response of the column is determined to be absolutely affected by the gravity load compared to the lateral load.

• Structural Engineering and Mechanics
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• v.84 no.5
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• pp.665-673
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• 2022

Additive manufacturing is an emerging method to manufacture objects with complex shapes and intricate geometry, such as cellular structures. The cellular structures can widely be used in lightweight application as it provides a high strength-to-load ratio. Under the various testing condition, each topology shows different mechanical properties. This study investigates the structural response of various types of cellular structures in compression loading, both experimentally and numerically. For that purpose, honeycomb, modified honeycomb, and spiral-type topology were selected to investigate. Besides, structural properties change by changing the cell size for each topology is also investigated. The specimens were subjected to a compression test by a universal testing machine to determine the absorbed energy and other mechanical properties. An implicit numerical study was also conducted to determine cellular structure's mechanical characteristics. The experimental and numerical results show that the honeycomb structure absorbs the maximum energy compared to the other structures. The experimentally and numerically calculated absorbed energy for the 4.8 mm honeycomb structure was 32.2J and 30.63J, respectively. The results also show that the increase of cell size for a particular cellular structure reduces the energy-absorbing ability of that structure.

• Journal of the Korean Society of Clothing and Textiles
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• v.47 no.3
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• pp.409-424
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• 2023

This study aimed to reveal prospective fashion designers' predominant perceptions regarding the ideal body size and shape and to suggest an educational guideline for the design process. Sketch tasks and surveys involving the college students in a fashion design department were conducted over the course of a year. A total of 113 participants designed a white cotton shirt for women in their 30s and 40s. Immediately after the sketching task, the participants answered survey questions on the specific body sizes and shapes they had been picturing. According to the results, the participants designed shirts for a medium-sized, hourglass body shape. As the percentage of women in their 30s and 40s with an hourglass shape is low, a discrepancy exists between the ideal design and the body of the actual consumer. Furthermore, 55% of the participants indicated that they would change the design for a woman with a different body shape. The majority of the participants agreed that understanding the body shape and size is important when initiating ideas. These findings can help educators understand the importance of improving designers' awareness of various body sizes and shapes; they also suggest new directions for fashion design education.

• Current Optics and Photonics
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• v.7 no.4
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• pp.419-427
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• 2023

The structural design of an optical-telescope assembly (OTA) for satellite laser ranging (SLR) is conducted in two steps. First, the results of a parametric study of the major design variables (e.g. dimension and shape) of the OTA part are explained, and the detailed structural design of the OTA is derived, considering the design requirements. Among the structural-shape concepts of various OTAs, the Serrurier truss concept is selected in this study, and the collimation of the telescope according to the design variables is extensively discussed. After generating finite-element models for different structural shapes, self-gravity analyses are performed. To minimize the deflection and tilt of the mirror and frame for the OTA under the limited design requirements, a parametric study is conducted according to design variables such as the shapes of the upper and lower struts and the spider vane. The structural features found in the parametric study are described. Finally, the OTA structure is designed in detail to maintain the optical alignment by balancing the gravity deflections of the upper and lower trusses using the optimal combination of the parameters. Additionally, thermal analysis of the optical telescope design is evaluated.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.5A
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• pp.817-822
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• 2006

Post-tensioning the full-depth precast slab longitudinally is to eliminate the tensile stresses in the transverse joints and to prevent any leakage through the joints. When the prestressing is applied to full-depth precast slab which does not composite steel girder, stress concentration occurs at the corners of shear pocket, and compressive stress is not uniformly distributed in the section of precast slab. In this paper, full-depth precast slabs using four different shapes of shear pockets are analyzed by commercial finite element program. Round type of shear pockets is superior to reduction in stress concentration.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.4A
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• pp.375-382
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• 2010

This paper presents the extraction of natural frequencies and mode shapes of a cable-stayed bridge using data acquired from GNSS. The response signals of 6 GNSS measuring points installed at the Seohae cable-stayed bridge are used for analysis of dynamic characteristics. Using normalization process and a third order Butterworth filter for the measured signals, the related pass band's signals have been isolated. Then, the acceleration data by double differentiation for these signals are obtained. Total five natural frequencies have been extracted by the fast Fourier transform and compared to the results of different studies. For the acceleration obtained from GNSS signals, the mode shapes of the bridge have been successfully extracted by TDD technique.

• Geomechanics and Engineering
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• v.35 no.2
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• pp.135-147
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• 2023

Sand columns in clayey soil are considered one of the most economical and environmentally-friendly soil-improving techniques. It improves the shear strength parameters, reduces the settlement, and increases the bearing capacity of clayey soils. The aim of this paper is to study the effect of grain shape in sand columns on their performance in improving the mechanical properties of clayey soils. An intensive series of consolidated-drained triaxial tests were performed on clay specimens only and clay specimens with sand columns. The parameters examined during the experimental work were grain shape in sand columns (angular, rounded, sub-rounded) and effective confining pressure (50 kPa, 100 kPa, 200 kPa). The results indicated that there is a significant improvement in the deviatoric stress and stiffness values of specimens with sand columns. Improving deviatoric stress values in the use of angular sand grains was found to be higher than those in the use of sub-rounded and rounded sand grains. A 187%, 159%, and 153% increment in deviatoric stress values were observed for the sand columns with angular, sub-rounded, and rounded grain shapes, respectively. The specimens were observed to be more contractive as the sand column was installed, and as the angularity of grains in the sand column was increased. Sand column installation improves significantly the angle of internal friction, and the effective angle of internal friction increases as the angularity of the sand grains increases.