• Journal of electromagnetic engineering and science
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• v.6 no.1
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• pp.36-46
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• 2006

In this paper, we present a two-element circularly-polarized antenna array for UHF-band RFID reader applications. The antenna element in the array is a comer-truncated rectangular patch placed on a thick plastic-foam dielectric. The patch is fed on one of its edges by a microstrip line printed on a separate thin substrate. The array antenna is fed by a microstrip power divider. Parametric studies on the patch are carried out, from which an optimum design of a single antenna element is derived. The element spacing and the feed network of the array are investigated. A commercial electromagnetic software is employed in the analysis and design of the antenna. The designed array is fabricated and tested. Measurements show good performance characteristics of the fabricated antenna: a 11.2-dBi gain, a reflection coefficient of - 14 dB, an axial ratio less than 3 dB over 3-dB beamwidths of 40 and 60 degrees on two principal planes.

• Transactions of the Korean Society of Automotive Engineers
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• v.17 no.5
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• pp.74-83
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• 2009

Recently, usage of electric and electronic system for car increases rapidly. Consequently power monitoring supplied to the system is essential for management and controlling. Generally, battery status is monitored through measuring and diagnosing the current measurement method utilizing Hall Effect. Therefore, in this paper, we analysed magnetic field to develop the solution of DC current sensor using Hall Effect which is the core of design and development. By analysing the magnetic field by FEM using Maxwell 3D software, the location of the highest output current and stable part in the Hall IC sensor was shown. Also, the optimal core design of DC current sensor using parametric and Simplex method was presented. A car battery charge and discharge process dependant on time effect on the changing of magnetic field was simulated and compared to the result from the experiment result of actual vehicle.

• 한국전산유체공학회:학술대회논문집
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• 2008.03b
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• pp.218-219
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• 2008

A gas-liquid centrifugal separator is widely used in industry because of its simple geometry and little maintenance. Also, these separators have considerable advantages over filters, scrubbers or precipitators in term of compact design, low pressure drop and higher capacity. A gas-liquid centrifugal separator is a device that utilizes centrifugal force and low pressure to separate liquid from gas by density difference. Design parameters such as length of separation space, swirl vane exit angle, inlet to outlet pipe diameter ratio, models for separation efficiency and low pressure drop as a function of physical dimension are not available in literature. In present study, length of separation space (from vane to gas exit opening) has been studied using CFD. The 3-D Navier-Stokes equations are numerically solved using a fully implicit finite volume scheme. Based upon the obtained solutions, tangential velocities, centrifugal forces, vortices and total pressure losses are analyzed to find the best design parameters.

• Journal of KIISE
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• v.44 no.3
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• pp.332-337
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• 2017

When using IFC data consisting of STEP schema based on the EXPRESS language, it is not easy for collaborating project stakeholders to share BIM modeling shape information. The IFC viewer application must be installed on the desktop PC to review the BIM modeling shape information defined within the IFC, because the IFC viewer application not only parse STEP structure information model but also process the 3D feature construction for a 3D visualization. Therefore, we propose a lightweight data structure design for web visualization by parsing IFC data and constructing 3D modeling data. Our experimental results show the weight reduction of IFC data is about 40% of original file size and the web visualization is able to see the same quality with all web browsers which support WebGL on PCs and smartphones. If applied research is conducted about the web visualization based on IFC data of the last construction phase, it could be utilized in various fields ranging from the facility maintenance to indoor location-based services.

• Advances in Computational Design
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• v.5 no.4
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• pp.381-396
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• 2020

This study aimed to develop an optimal model of transportation for people with disabilities. To achieve this goal, powers of research and design should be involved, including CAD software. This paper investigates both: the concept of optimal model of transportation for people with disabilities (functional, ergonomic, constructive, technological and aesthetic solutions included); and its implementation as a fully-fledged 3D-model designed in SolidWorks environment. The optimal model of transportation is complex and consists of two objects. The first object is for indoors that is a wheelchair, the second one is for street driving that is an individual vehicle. The optimal model of transportation is universal and multifunctional, which have become possible with parametric feature-based approach utilized in SolidWorks.

• Structural Engineering and Mechanics
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• v.42 no.5
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• pp.645-675
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• 2012

An effective design technique for symmetrical coupled shear walls is presented. Proposed formulation including assumptions and steps with mathematical formulation has been elaborated to make the design technique. An example has been considered to validate the technique with the DRAIN-3DX (1993) and SAP V 10.0.5 (2000) nonlinear programs. Parametric study has also been considered to find out the limitations along with remedial action of this technique. On the other hand, nonlinear static analysis is considered to determine the response reduction factor of coupled shear walls. Finally, it has been concluded in this paper that the proposed design technique can be considered to design the coupled shear walls under seismic motion.

• Structural Engineering and Mechanics
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• v.84 no.6
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• pp.723-731
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• 2022

Functionally graded materials (FGMs) have been spotlighted as an advanced composite material, accordingly the intensive studies have focused on FGMs to examine their mechanical behaviors. Among them is thermal buckling which has been a challenging subject, because its behavior is connected directly to the safety of structural system. In this context, this paper presents the numerical analysis of thermal buckling of metal-ceramic functionally graded (FG) plates. For an accurate and effective buckling analysis, a new numerical method is developed by making use of (1,1,0) hierarchical model and 2-D natural element method (NEM). Based on 3-D elasticity theory, the displacement field is expressed by a product of 1-D assumed thickness monomials and 2-D in-plane functions which are approximated by NEM. The numerical method is compared with the reference solutions through the benchmark test, from which its numerical accuracy has been verified. Using the developed numerical method, the critical buckling temperatures of metal-ceramic FG plates are parametrically investigated with respect to the major design parameters.

• KSTLE International Journal
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• v.3 no.1
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• pp.1-6
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• 2002

The purpose of this paper is to investigate the effects of design parameters on the friction loss in piston skirt. An analytical model to describe the friction characteristics of piston skirt has been presented, which is based on the secondary motion of piston and mixed lubrication theory, It could be shown that the skirt friction closely depends on the side force acted on the piston pin. The side force is inf1uenced by cylinder pressure at low engine speed, but by inertia force at high engine speed. The usage of extensive skirt area and low weight piston is effective to reduce the friction loss at high speed. The low viscosity oil considerably decreases viscous friction as engine speed increases, but it increases boundary friction at low engine speed. From the parametric study, it is found that the skirt axial profile is the most important design parameter related to the reduction of skirt friction.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.14 no.3
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• pp.74-84
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• 2015

The core activities of a bicycle manufacturer are design, engineering analysis, and manufacturing. Therefore, it is important to develop a configuration design system for bicycles in order to automate the design process and facilitate the use of design data in engineering analysis and manufacturing. In this paper, we present a method to develop a bicycle configuration design system based on the part-shape information model. The proposed method enables the construction of a CAD library using modeling functions with equations and parameters that are common to most 3D mechanical CAD systems. Furthermore, the part-shape information model ensures the independence between the configuration design system and the library, making it possible to extend the CAD library flexibly without changing the system architecture.

• Steel and Composite Structures
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• v.46 no.3
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• pp.403-416
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• 2023

This paper summarised and re-examined the theoretical basis of the commonly used design rule developed by Cochrane in the 1920s to consider staggered bolt holes in tension members, i.e., the s²/4g rule. The rule was derived assuming that the term two times the bolt hole diameter (2d₀) in Cochrane's original equation could be neglected, and assuming a value of 0.5 for the fractional deduction of a staggered hole in assessing the net section area. Although the s²/4g rule generally provides good predictions of the staggered net section area, the above-mentioned assumptions used in developing the rule are doubtful, in particular for a connection with a small gauge-to-bolt-hole diameter (g/d₀) ratio. It was found that the omission of 2d₀ in Cochrane's original equation appreciably overestimates the net section area of a staggered bolted connection with a small g/d₀ ratio. However, the assumed value of 0.5 for the fractional deduction of a staggered hole underestimates the staggered net section area for small g/d₀ ratios. To improve the applicability of the above two assumptions, a modified design equation, which covers a full range of g/d₀ ratio, was proposed to accurately predict the staggered net section area and was validated by the existing test data from the literature and numerical data derived from this study. Finally, a reliability analysis of the test and numerical data was conducted, and the results showed that the reliability of the modified design equation for evaluating the net section resistance of staggered bolted connections can be achieved with the partial factor of 1.25.