• Steel and Composite Structures
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• v.33 no.6
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• pp.793-803
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• 2019

Concrete-filled steel tubular (CFST) beam-columns are widely used owing to their good performance. They have high strength, ductility, large energy absorption capacity and low costs. Externally stiffened CFST beam-columns are not used widely due to insufficient design equations that consider all parameters affecting their behavior. Therefore, effect of various parameters (global, local slenderness ratio and adding hoop stiffeners) on the behavior of CFST columns is studied. An experimental study that includes twenty seven specimens is conducted to determine the effect of those parameters. Load capacities, vertical deflections, vertical strains and horizontal strains are all recorded for every specimen. Ratio between outer diameter (D) of pipes and thickness (t) is chosen to avoid local buckling according to different limits set by codes for the maximum D/t ratio. The study includes two loading methods on composite sections: steel only and steel with concrete. The case of loading on steel only, occurs in the connection zone, while the other load case occurs in steel beam connecting externally with the steel column wall. Two failure mechanisms of CFST columns are observed: yielding and global buckling. At early loading stages, steel wall in composite specimens dilated more than concrete so no full bond was achieved which weakened strength and stiffness of specimens. Adding stiffeners to the specimens increases the ultimate load by up to 25% due to redistribution of stresses between stiffener and steel column wall. Finally, design equations previously prepared are verified and found to be only applicable for medium and long columns.

• Tunnel and Underground Space
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• v.11 no.1
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• pp.30-35
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• 2001

Focusing on the bench length, this paper presents the results of 3-dimensional elafto-plastic FE Analysis un tunnels of full face, mini-bench and short bench excavated in weathered rock. Influences of unsupported span, horizontal to vertical stress ratio, thickness of shotcrete on the behavior of rock and support were a1so studied. Results showed that displacements of mini-bench tunnels responded more sensitively to bench lengths than those of short bench. The effects of bench excavation on upper half displacement increased with longer unsupported span. Horizontal to vertical stress ratio showed a greater influence on displacement and preceding displacement ratio or sidewall rather than those of crown and invert.

• Korean Journal of Applied Biomechanics
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• v.28 no.2
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• pp.135-141
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• 2018

Objective: The purpose of this study was to investigate the effect of functional ankle instability (FAI) and surgical treatment (ST) on postural stability and leg stiffness during vertical-drop landing. Method: A total of 21 men participated in this study (normal [NOR]: 7, FAI: 7, ST: 7). We estimated dimensionless leg stiffness as the ratio of the peak vertical ground reaction force and the change in stance-phase leg length. Leg length was calculated as the distance from the center of the pelvis to the center of pressure under the foot. Furthermore, the analyzed variables included the loading rate and the dynamic postural stability index (DPSI; medial-lateral [ML], anterior-posterior [AP], and vertical [V]) in the initial contact phase. Results: The dimensionless leg stiffness in the FAI group was higher than that of the NOR group and the ST group (p = .018). This result may be due to a smaller change in stance-phase leg length (p = .001). DPSI (ML, AP, and V) and loading rate did not show differences according to the types of ankle instability during drop landing (p > .05). Conclusion: This study suggested that the dimensionless leg stiffness was within the normal range in the ST group, whereas it was increased by the stiffness of the legs rather than the peak vertical force during vertical-drop landing in the FAI group. Identifying these potential differences may enable clinicians to assess ankle instability and design rehabilitation protocols specific for the impairment.

• International Journal of Naval Architecture and Ocean Engineering
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• v.12 no.1
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• pp.617-635
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• 2020

The purpose of this study is to discuss how to improve the maneuverability of lifting and diving for underwater vehicle's vertical motion. Therefore, to solve these problems, applied the 3-D numerical simulation, Taguchi's Design of Experiment (DOE), and intelligent parameter design methods, etc. We planned four steps as follows: firstly, we applied the 2-D flow simulation with NACA series, and then through the Taguchi's dynamic method to analyze the sensitivity (β). Secondly, take the data of pitching torque and total resistance from the Taguchi orthogonal array (L9), the ignal-to-noise ratio (SNR), and analysis each factorial contribution by ANOVA. Thirdly, used Radial Basis Function Network (RBFN) method to train the non-linear meta-modeling and found out the best factorial combination by Particle Swarm Optimization (PSO) and Weighted Percentage Reduction of Quality Loss (WPRQL). Finally, the application of the above methods gives the global optimum for multi-quality characteristics and the robust design configuration, including L/D is 9.4:1, the foreplane on the hull (Bow-2), and position of the sail is 0.25 Ls from the bow. The result shows that the total quality is improved by 86.03% in comparison with the original design.

• Korean Journal of Computational Design and Engineering
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• v.12 no.2
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• pp.137-145
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• 2007

This paper concerns about residential environment analysis program implementation for design and analysis on public housing complexes such that view and daylight analysis processes are automated and integrated into existing design routine to achieve better design efficiency. Considering the architectural design trends this paper chooses ArchiCAD as a platform for a CAD system, which contains the concepts such as integrated object-oriented CAD, virtual building and BIM. Residential environment analysis system consists of three components. The first component is the 3D modeling part defining 3D form information for external geographic contour models, site models and interior/exterior of apartment buildings. The second is the parametric library part handling the design parameters for view and daylight analysis. The last is the user interface for the input/output and integration of data for the environment analysis. Daylight analysis shows rendered images as well as results of daylight reports and grades per time and performs the calculations for floor shadow. It separates the site-only analysis from the analysis of site and exterior environmental parameters. View analysis considers horizontal and vertical view angles to produce view image from each unit and uses the bitmap analysis method to determine opening ratio, scenery ratio and void ratio. We could expect better performance and precision from this residential environment analysis system than the existing 2D drawing based view and daylight analysis methods and overcome the existing one-way flow of design information from 3D form to analysis reports so that site design modifications are automatically reflected on analysis results. Each part is developed in a module so that further integration and extension into other related estimation and construction management systems are made possible.

• Journal of the Korea Concrete Institute
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• v.14 no.6
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• pp.874-882
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• 2002

Currently, deep beams are designed according to ACT 318-99 equations derived from experimental data for slender beams with normal-strength concrete. In addition, there is relatively limited information on high-strength concrete deep beams with shear reinforcement. The purpose of this experimental study is to investigate the shear behavior of high-strength concrete deep beams and to grasp the conservatism of ACI shear design provisions. Experimental results on the shear behavior of 22 deep beams under two equal symmetrically placed point loads are reported. compressive strength of concrete cylinder was 800kgf/$\textrm{cm}^2$, and main variables were vertical and horizontal shear reinforcement and shear span-to-overall depth ratio (а/h). Test results showed that for high-strength concrete deep beams with shear span-to-overall depth ratio exceeding 0.75, the vertical shear reinforcement more effectively resisted the shear load than horizontal shear reinforcement. In high-strength concrete deep beams, ACI shear design provisions tended to underestimate the effect of strut-tie action and vertical shear reinforcement and overestimate the ones of horizontal shear reinforcement. Based on the experimental results of high-strength concrete deep beams and shear friction theory, this study modified the equations on the shear capacity specified by the ACI provisions.

• Journal of the Korea Fashion and Costume Design Association
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• v.21 no.4
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• pp.115-126
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• 2019

The purpose of this study is to analyze the characteristics of older women's torso shapes. The data was collected from the 7th Size Korea, which featured 453 women between the ages of 70-85. A factor analysis was performed of 31 indices, including seventeen based on height and length measurements, eight based on circumference measurements, and six based on torso flattening. The torso shape was determined from seven factors: torso flatness ratio, shape of the side upper torso, vertical size of upper torso, silhouette of the torso, silhouette of the bust and abdomen, shape of the hip, and the vertical size of the back of upper torso. The torso shapes of older women were classified into three types based on the results of the factor analysis. Type 1 is called the large rectangle type. They have the lowest degree of forward bend in the torso, the largest vertical and horizontal size, a round body shape, and the upper torso is gently curved. Type 2 is called the inverted triangle type. They also have a round body shape, but the abdominal size is relatively small compared to the size of the bust, and also have an open and drooping bust, and the biggest degree of forward bend in the torso. Type 3 is called the square type. They are characterized by drooping hips, the smallest vertical and horizontal sizes, and the gentlest curve of the torso.

• Journal of Advanced Navigation Technology
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• v.27 no.4
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• pp.463-468
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• 2023

In this paper, we proposed reconfigurable dual polarization patch array antenna that can select two polarizations(Vertical, RHCP) using defected ground structure and Pin diode. The proposed antenna was designed arranging a circular polarization patch antenna implemented with a square microstrip patch and two slots 3x3 at 25.8mm placed, a half-wavelength of 5.8 GHz. Conect the pin diode and the capacitor to the slot diagonally placed on the ground of each antennas, and select polarization using the open/short operating according to the application of DC voltage to the pin diode. As a result of the design, the gain of the antenna is 11.7 dBi at vertical polarization and 11.6 dBic at RHCP. The axial ratio is 20.3 dB at 1.8 dB vertical polarization at RHCP. Mutual Coupling is Maximum to -20.8 dB for vertical polarization and Maximum to -30.1 dB for RHCP.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.38 no.9
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• pp.643-651
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• 2001

Fused vertical directional coupler switches (FVCSs) with switching operation induced section (SOIS) and extinction ratio enhanced section (ERES) are proposed. In these FVCSs, switching operation is achieved by changing the refractive indices of both cores in SOIS and improvement of extinction ratios larger than 30dB for both cross and bar states is achieved by controlling the asymmetry of refractive indices between both cores in ERES. In addition, the design guidelines to have high extinction ratios larger than 30dB with large tolerances of the refractive index of cores are presented.

• 한국연소학회:학술대회논문집
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• 1998.10a
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• pp.79-84
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• 1998

In this paper we show design and operation of 1MWth pulverized coal combustion test facility. The test facility is consists of coal feeding system, furnace and flue gas treatment system. The furnace is equipped with a top-fired burner in order to avoid influence of gravity on the coal particles. There are two part of vertical(VP) and horizontal pass(HP) at furnace. We can measure temperature and species of coal flames in vertical pass. Also, there is horizontally arranged section where investigation regarding corrosion and deposit formation will be carried out. The burner of combustor was externally air staging burner(EASB) type made by IFRF. The pulverized high bituminous(Blair athol) coal from Australia was used as fuel, and the particle size less than 80 ${\mu}m$ was 83.4%. Overall excess air ratio was 1.2.