• Journal of information and communication convergence engineering
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• v.14 no.4
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• pp.207-214
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• 2016

In this paper, we propose a radial reference map-based location fingerprinting technique with constant spacing from an access point (AP) to all reference points by considering the minimum dynamic range of the received signal strength indicator (RSSI) obtained through an experiment conducted in an indoor environment. Because the minimum dynamic range, 12 dBm, of the RSSI appeared every 20 cm during the training stage, a cell spacing of 80 cm was applied. Furthermore, by considering the minimum dynamic range of an RSSI in the location estimation stage, when an RSSI exceeding the cumulative average by ${\pm}6dBm$ was received, a previously estimated location was provided. We also compared the location estimation accuracy of the proposed method with that of a conventional fingerprinting technique that uses a grid reference map, and found that the average location estimation accuracy of the conventional method was 21.8%, whereas that of the proposed technique was 90.9%.

• International Journal of Naval Architecture and Ocean Engineering
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• v.7 no.5
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• pp.906-919
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• 2015

The Deep Draft Semi-Submersible (DDS) concepts are known for their favourable vertical motion performance. However, the DDS may experience critical Vortex-Induced Motion (VIM) stemming from the fluctuating forces on the columns. In order to investigate the current-induced excitation forces of VIM, an experimental study of flow characteristics around four square-section cylinders in a square configuration is presented. A number of column spacing ratios and array attack angles were considered to investigate the parametric influences. The results comprise flow patterns, drag and lift forces, as well as Strouhal numbers. It is shown that both the drag and lift forces acting on the cylinders are slightly different between the various L/D values, and the fluctuating forces peak at L/D = 4.14. The lift force of downstream cylinders reaches its maximum at around ${\alpha}=15^{\circ}$. Furthermore, the flow around circular-section-cylinder arrays is also discussed in comparison with that of square cylinders.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.1081-1084
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• 2008

Column specimens were constructed with main parameters significantly affecting the strength of the compression lap splice, such as lap length, spacing of lapped bars, amount and location of transverse reinforcements, and concrete strength. An experimental study has been conducted with column specimens in concrete strength of 40 to 60 MPa. Diameters of lapped reinforcing bars are 22 mm. An axial load was monotonically applied to the column specimens. All specimens failed in a brittle sudden manner and cover concrete was blasted out at maximum load. Compression lap splice strengths of specimens were evaluated from strains measured at the beginning of the lap length. Effects of the main parameters on the strengths of compression lap splice are assessed. Similarly to strengths of tension lap slice, the compression splice strength is found to be affected by lap length, spacing of lapped bars, transverse reinforcements.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.35D no.12
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• pp.1-11
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• 1998

A line profile synthesis method is presented that minimizes the nearest-neighbor crosstalk peak level for high-speed pulse transmission in multi-coupled microstrip signal buses. We adopted the optimization technique for the reflected wave control on bus lines resulting in increasing the average spacing between strip conductors, since in a parallel-conductor bus the crosstalk energy is concentrated at the nearest neighbors of the driven line. The generalized S-matrix technique is applied for the input and output waveform prediction, and crosstalk characteristics of various nonuniform lines synthesized for increasing the average spacing are analyzed by comparing each other. Simulation results demonstrate that the Chebyshev taper with dips is adequate to significantly minimize the crosstalk peak level under the satisfactory waveform integrity since the profile is oriented to evenly reflect significant pulse spectra within the frequency range of pulse.

• Geomechanics and Engineering
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• v.21 no.4
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• pp.379-390
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• 2020

The behavior of a piled raft system in multi-layered soil subjected to vertical loading has been studied numerically using 3D finite element analysis. Initially, the 3D finite element model has been validated by analytically simulating the field experiments conducted on vertically loaded instrumented piled raft. Subsequently, a comprehensive parametric study has been conducted to assess the performance of a combined piled raft system in terms of optimum pile spacing and settlement of raft and piles, in multi-layered soil stratum subjected to vertical loading. It has been found that a combined pile raft system can significantly reduce the total settlement as well as the differential settlement of the raft in comparison to the raft alone. Two different arrangements below the piled raft with the same pile numbers show a significant amount of increase of load transfer of piled raft system, which is in line with the load transfer mechanism of a piled raft. A methodology for the factor of safety assessment of a combined pile raft foundation has been presented to improve the performance of piled raft based on its serviceability requirements. The findings of this study could be used as guidelines for achieving economical design for combined piled raft systems.

• Wind and Structures
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• v.28 no.6
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• pp.355-367
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• 2019

Control of horseshoe vortex in the circular cylinder-plate juncture using vortex generator (VG) was studied at $Re_D$(where D is the diameter of the cylinder) = $2.05{\times}10^5$. Impact of a number of parameters e.g., the shape of the VG's, number of VG pairs (n), spacing between the VG and the cylinder leading edge (L), lateral gap between the trailing edges of a VG pair (g), streamwise gap between two VG pairs ($S_{VG}$) and the spacing between the two VG's in parallel arrangement ($Z_{VG}$) etc. were investigated on the horseshoe vortex control. The study is conducted using surface oil flow visualization and surface pressure measurements in low speed wind tunnel. It is observed that all the parameters studied have significant control effect, either by reduction in separation region or by lowering the adverse pressure along the symmetric axis upstream of the juncture.

• Geomechanics and Engineering
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• v.32 no.2
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• pp.193-207
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• 2023

In general, the numerous classical approaches available in the literature can anticipate the settlement of shallow foundations. As long as the footings are not in close proximity to other subsurface buildings, the findings achieved using these methods are legitimate and acceptable. However, due to increased urbanisation and land scarcity, footings are frequently built close together. As a result, these footings' settlement behaviour differs from those of isolated footings. A simpler approach for assessing the settlement behaviour of two square or rectangular footings placed in close proximity is presented in this work. A Parametric study has been carried out to examine the interference effect on the settlement of these footings placed in close vicinity on the surface of a homogeneous, isotropic and elastic soil medium. The interaction factors are examined by varying the different aspect ratios (L/B), clear spacing ratio (S/B) and intensity of loading on the right footing with respect to the left footing. Further, variation of the settlement ratio (δ/B) with respect to embedment depth ratio D_f/B is examined. For square and rectangular footings, the interference settlement profile is also investigated by varying the clear spacing ratio (S/B) and the degree of loading. The results were compared to 3D finite element analysis and experimental data that were available.

• 한국약용작물학회:학술대회논문집
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• 2010.10a
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• pp.266-267
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• 2010

• Korean Journal of Remote Sensing
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• v.22 no.5
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• pp.351-356
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• 2006

Based on current practical needs for geo-spatial information on mobile platform, the main theme of this study is a design and implementation of dynamic 3D terrain rendering system using spaceborne imagery, as a kind of texture image for photo-realistic 3D scene generation on mobile environment. Image processing and 3D graphic techniques and algorithms, such as TIN-based vertex generation with regular spacing elevation data for generating 3D terrain surface, image tiling and image-vertex texturing in order to resolve limited resource of mobile devices, were applied and implemented by using graphic pipeline of OpenGL|ES (Embedded System) API. Through this implementation and its tested results with actual data sets of DEM and satellite imagery, we demonstrated the realizable possibility and adaptation of complex typed and large sized 3D geo-spatial information in mobile devices. This prototype system can be used to mobile 3D applications with DEM and satellite imagery in near future.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.29 no.2 s.233
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• pp.325-332
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• 2005

This paper presents a study on defects in pearlite lamella structure of high carbon steel by means of finite-element method(FEM) simulation. High carbon pearlite steel wire is characterized by its nano-sized microstructure feature of alternation ferrite and cementite. FEM simulation was performed based on a suitable FE model describing the boundary conditions and the exact material behavior. Due to the lamella structure in high carbon pearlite steel wire, material plastic behavior was taken into account on deformation of ferrite and cementite. The effects of many important parameters(reduction in area, semi-die angle, lamella spacing, cementite thickness) on wire drawing process can be predicted by DEFORM-2D. It is possible to obtain the important basic data which can be guaranteed in the ductility of high carbon steel wire by using FEM simulation.