• Journal of the Korea Institute of Information and Communication Engineering
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• v.9 no.5
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• pp.1089-1095
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• 2005

This paper presents a new low-cost Built-In Self-Test (BIST) circuit for 50Hz low noise amplifier (LNA). The BIST circuit is designed for system-on-chip (SoC) transceiver environment. The proposed BIST circuit measures the LNA specifications such as input impedance, voltage gaih, noise figure, and input return loss all in a single SoC environment.

• Journal of Welding and Joining
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• v.19 no.2
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• pp.98-103
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• 2001

Root gap out of standard by welding deformation is frequently produced at butt weld joints of steel bridge. For example although standard root gap is below 6mm at butt weld joints of plates under 15mm thickness. maximum 35mm root opening is produced at the weld field. At this case, the part out of standard is generally built up and the rest part is welded by WPS. Direct welding without built-up welding is preferred in weld field because built-up welding process bring about the cost-up at manufacturing. To apply this direct weld to root gap out of standard, the investigation about mechanical properties and fatigue at weldment is required. Inthisstudy, therefore the verification for direct weld without built up is performed at weldment as root gap. It includes tension, bending. hardness, impact and fatigue test for each welding specimen of 6mm, 25mm, 35mm root gap.

• Architectural research
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• v.12 no.1
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• pp.15-23
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• 2010

This paper will discuss three different ways of framing relationships between identity and built forms mainly through the theoretical frame works of David Harvey, Christine M. Boyer, Jane M. Jacobs, Doreen Massey, Paul Rabinow, and Michel Foucault. From these scholars, this paper will argue the relationships between identity and built forms are categorized as such: "Becoming", "Politics of Difference", and "Construction of Self". Besides these three approaches of framing identity and built forms, relevant ideas will be drawn from the work of other scholars in so far as their theoretical positions relate and support these three key frameworks. To approach the critical points of each debate, these three categories are further analyzed by juxtaposing the epistemological positions between them. Through the comparisons, this paper illustrates the interrelationships and interdependence of these three categories whose discursive power gains rapid popularity in Western scholarships. By incorporating the three ways to view the relationship between built form and the identity of social groups, drawn is a suggestion for a broader imagining of new spatial identity.

• International conference on construction engineering and project management
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• 2009.05a
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• pp.920-927
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• 2009

Many schedule delays and cost overruns in interior construction are caused by a lack of understanding in detailed and complicated interior works. To minimize these potential impacts in interior construction, a systematic approach for project managers to detect discrepancies at early stages and take corrective action through use of visualized data is required. This systematic implementation is still challenging: monitoring is time-consuming due to the significant amount of as-built data that needs to be collected and evaluated; and current interior construction progress reports have visual limitations in providing spatial context and in representing the complexities of interior components. To overcome these issues, this research focuses on visualization and computer vision techniques representing interior construction progress with photographs. The as-planned 3D models and as-built photographs are visualized in a 3D walk-through model. Within such an environment, the as-built interior construction elements are detected through computer vision techniques to automatically extract the progress data linked with Building Information Modeling (BIM). This allows a comparison between the as-planned model and as-built elements to be used for the representation of interior construction progress by superimposing over a 3D environment. This paper presents the process of representing and detecting interior construction components and the results for an ongoing construction project. This paper discusses implementation and future potential enhancement of these techniques in construction.

• Steel and Composite Structures
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• v.33 no.4
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• pp.595-614
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• 2019

In cold-formed steel (CFS) structures, such as trusses, transmission towers and portal frames, the use of back-to-back built-up CFS unequal angle sections are becoming increasingly popular. In such an arrangement, intermediate welds or screw fasteners are required at discrete points along the length, preventing the angle sections from buckling independently. Limited research is available in the literature on axial strength of back-to-back built-up CFS unequal angle sections. The issue is addressed herein. This paper presents an experimental investigation on both the welded and screw fastened back-to-back built-up CFS unequal angle sections under axial compression. The load-axial shortening and the load verses lateral displacement behaviour along with the deformed shapes at failure are reported. A nonlinear finite element (FE) model was then developed, which includes material non-linearity, geometric imperfections and modelling of intermediate fasteners. The FE model was validated against the experimental test results, which showed good agreement, both in terms of failure loads and deformed shapes at failure. The validated FE model was then used for the purpose of a parametric study to investigate the effect of different thicknesses, lengths and, yield stresses of steel on axial strength of back-to-back built-up CFS unequal angle sections. Five different thicknesses and seven different lengths (stub to slender columns) with two different yield stresses were investigated in the parametric study. Axial strengths obtained from the experimental tests and FE analyses were used to assess the performance of the current design guidelines as per the Direct Strength Method (DSM); obtained comparisons show that the current DSM is conservative by only 7% on average, while predicting the axial strengths of back-to-back built-up CFS unequal angle sections.

• Steel and Composite Structures
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• v.31 no.6
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• pp.601-615
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• 2019

In cold-formed steel (CFS) structures, such as trusses, wall frames and columns, the use of back-to-back built-up CFS angle sections are becoming increasingly popular. In such an arrangement, intermediate fasteners are required at discrete points along the length, preventing the angle-sections from buckling independently. Limited research is available in the literature on the axial strength of back-to-back built-up CFS angle sections. The issue is addressed herein. This paper presents the results of 16 experimental tests, conducted on back-to-back built-up CFS screw fastened angle sections under axial compression. A nonlinear finite element model is then described, which includes material non-linearity, geometric imperfections and explicit modelling of the intermediate fasteners. The finite element model was validated against the experimental test results. The validated finite element model was then used for the purpose of a parametric study comprising 66 models. The effect of fastener spacing on axial strength was investigated. Four different cross-sections and two different thicknesses were analyzed in the parametric study, varying the slenderness ratio of the built-up columns from 20 to 120. Axial strengths obtained from the experimental tests and finite element analysis were used to assess the performance of the current design guidelines as per the Direct Strength Method (DSM); obtained comparison showed that the DSM is over-conservative by 13% on average. This paper has therefore proposed improved design rules for the DSM and verified their accuracy against the finite element and test results of back-to-back built-up CFS angle sections under axial compression.

• Steel and Composite Structures
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• v.42 no.1
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• pp.1-22
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• 2022

In cold-formed steel (CFS) structures, such as trusses, transmission towers and portal frames, the use of back-to-back built-up CFS unequal angle sections are becoming increasingly popular. In such an arrangement, intermediate welds or screw fasteners are required at discrete points along the length, preventing the angle sections from buckling independently. Limited research is available in the literature on axial strength of back-to-back built-up CFS unequal angle sections. The issue is addressed herein. This paper presents an experimental investigation reported by the authors on back-to-back built-up CFS unequal angle sections with intermediate stiffeners under axial compression. The load-axial shortening behaviour along with the deformed shapes at failure are reported. A nonlinear finite element (FE) model was then developed, which includes material non-linearity, geometric imperfections and modelling of intermediate fasteners. The FE model was validated against the experimental test results, which showed good agreement, both in terms of failure loads and deformed shapes at failure. The validated finite element model was then used for the purpose of a parametric study comprising 96 models to investigate the effect of longer to shorter leg ratios, stiffener provided in the longer leg, thicknesses and lengths on axial strength of back-to-back built-up CFS unequal angle sections. Four different thicknesses and seven different lengths (stub to slender columns) with three overall widths to the overall depth (B/D) ratios were investigated in the parametric study. Axial strengths obtained from the experimental tests and FE analyses were used to assess the performance of the current design guidelines as per the Direct Strength Method (DSM); obtained comparisons show that the current DSM is conservative by only 7% and 5% on average, while predicting the axial strengths of back-to-back built-up CFS unequal angle sections with and without the stiffener, respectively.

• Korean Journal of Computational Design and Engineering
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• v.16 no.2
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• pp.126-136
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• 2011

The existing approaches to freeform building construction cause many problems. However, recent BIM technique development based on parametric modeling method and improvement of freeform materials manufacturing technology using IT technology encouraged many advanced countries to try experimental projects. Thus, laser scanning technique is in the limelight as a new alternative in the field of freeform building construction and inspection. This study selected a domestic small freeform building and practiced laser scanning and as-planned modeling by using Reverse Engineering. Then each deviation was comparatively analyzed through figures which extracted data by numerically analyzing the newly modeled as-built and Excel spread sheet. Through the process, limits and follow-up research subjects are discussed as well.

• Steel and Composite Structures
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• v.34 no.3
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• pp.347-359
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• 2020

The objective of this study is to experimentally scrutinize the axial performance of built-up concrete filled steel tube (CFT) columns composed of steel plates. In this case, the main parameters cross section types, compressive strength of filled concrete, and the effect of welding lines. Welded built-up steel box columns are fabricated by connecting two pieces of cold-formed U-shaped or four pieces of L-shaped thin steel plates with continuous penetration groove welding line located at mid-depth of stub column section. Furthermore, traditional square steel box sections with no welding lines are investigated for the comparison of axial behavior between the generic and build-up cross sections. Accordingly, 20 stub columns with thickness and height of 2 and 300 mm have been manufactured. As a result, welding lines in built-up specimens act as stiffeners because have higher strength and thickness in comparison to the plates. Subsequently, by increasing the welding lines, the load bearing capacity of stub columns has been increased in comparison to the traditional series. Furthermore, for specimens with the same confinement steel tubes and concrete core, increment of B/t ratio has reduced the ductility and axial strength.

• Transactions on Electrical and Electronic Materials
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• v.18 no.5
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• pp.257-260
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• 2017

In this paper, we present the design of a 4.5 V low dropout (LDO) voltage regulator implemented in the 130 nm CMOS process. The design uses a two-stage cascaded operational transconductance amplifier (OTA) as an error amplifier, with a body bias technique for reducing dropout voltages. PMOS is used as a pass transistor to ensure stable output voltages. The results show that the proposed LDO regulator has a dropout voltage of 32.06 mV when implemented in the130 nm CMOS process. The power dissipation is only 1.3593 mW and the proposed circuit operates under an input voltage of 5V with an active area of $703{\mu}m^2$, ensuring that the proposed circuit is suitable for low-power applications.