• Transactions of the Korean Society of Mechanical Engineers B
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• v.25 no.8
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• pp.1005-1012
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• 2001

When vortex tubes are applied to enhance the coefficient of performance of refrigeration system, the smaller one is preferable. However, the existing vortex generator with a nozzle hole diameter of 0.5mm was not suitable due to chocking of the nozzle hole. Therefore, experimental investigation was made to find an appropriate geometry of vortex generator, which could give a comparable effect of energy separation to commercial ones without chocking problem. The tested vortex generators were tangential and spiral types, which had single inducing channel with larger cross-sectional area than that of conventional multi-hole ones. The experimental result showed that the performance of the spiral type was better than that of the tangential one. As a small size of spiral one, the diameter of cold-end orifice is proposed to an half of tube diameter for the application to refrigeration system, while cold mass fraction ratio is 0.5∼0.6 for a desirable operation.

• JSTS:Journal of Semiconductor Technology and Science
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• v.10 no.1
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• pp.37-44
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• 2010

New features of motion compensation, such as variable block size and multiple reference frames are introduced in H.264/AVC. However, these new features induce significant implementation complexity increases. In this paper, an efficient architecture for spiral-type motion estimation is proposed. First, we propose a hardware-friendly spiral search order. Then, an efficient processing element (PE) architecture for ME is proposed to achieve the proposed search order. The improved PE enables one-pixel-move of the reference pixel data to top, bottom, right, and left by four ports for input and output. Moreover, the parallel calculation architecture to calculate all block size with the SAD of 4x4 is introduced in the proposed architecture. As the result of hardware implementation, the hardware cost is about 145k gates. Maximum clock frequency is 134 MHz in the case of FPGA (Xilinx Vertex5) implementation.

• Advances in concrete construction
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• v.14 no.2
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• pp.79-92
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• 2022

The amount and configuration of transverse reinforcement are known as critical parameters that significantly affect the lateral confinement of concrete, the ductility capacity, and the plastic hinge length of RC columns. Based on test results, this study investigated the effect of the three variables on structural indexes such as neutral axis depth, lateral expansion of concrete, and ductility capacity. Five reinforced concrete column specimens were tested under cyclic flexure and shear while simultaneously subjected to a constant axial load. The columns were reinforced by two types of reinforcing steel: rectangular hoops and spiral type reinforcing bars. The variables in the test program were the shape, diameter, and yield strength of transverse reinforcement. The interactive influence of the amount of transverse reinforcement on the structural indexes was evaluated. Test results showed that when amounts of transverse reinforcement were similar, and yield strength of transverse reinforcement was 600 MPa or less, the neutral axis depth of a column with spiral type reinforcing bars was reduced by 28% compared with that of a column reinforced by existing rectangular hoops at peak strength. While the diagonal elements of spiral-type reinforcing bars significantly contributed to the lateral confinement of concrete, the strain of diagonal elements decreased with increases of their yield strength. It was confirmed that shapes of transverse reinforcement significantly affected the lateral confinement of concrete adjacent to plastic hinges. Transverse reinforcement with a yield strength exceeding 600 MPa, however, increased the neutral axis depth of normal-strength concrete columns at peak strength, resulting in reductions in ductility and energy dissipation capacity.

• Journal of the Korean Geotechnical Society
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• v.30 no.7
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• pp.55-61
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• 2014

The need of geothermal energy is constantly increasing for economical and environmental utilization. Horizontal ground heat exchangers (GHEs) can reduce installation cost and increase efficiency. There are many kinds of GHEs, and it is known that slinky and spiral coil type GHEs show high thermal performance. Therefore, this paper presents experimental results of heat exchange rates in horizontal slinky and spiral coil type GHEs installed in a steel box whose size is $5m{\times}1m{\times}1m$. Dried Joomunjin standard sand was filled in a steel box, and thermal response tests (TRTs) were conducted for 30 hours to evaluate heat exchange rates by changing different pitch spaces of horizontal slinky and spiral coil type GHEs. As a result, spiral coil type GHE showed 30~40% higher heat exchange rates per pipe length than horizontal slinky type GHEs. Furthermore, long pitch interval (Pitch/Diameter=1) showed 200~250% higher heat exchange rates per pipe length than short pitch interval (Pitch/Diameter=0.2) in both spiral coil and horizontal slinky type GHEs, respectively.

• Journal of the Korea institute for structural maintenance and inspection
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• v.16 no.6
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• pp.1-8
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• 2012

This study estimates the performance of confined concrete according to the configuration of transverse steel bars. The main test variables were the yield strength of spiral reinforcement and configuration of transverse reinforcement. A total of 27 specimens with rectangular cross section were cast and tested under monotonic concentric compression. R-type specimens with rectangular spirals, C-type specimens with circular spirals and O-type specimens with combined shape of rectangular and octagon were designed in this study. From experimental results, it is concluded that the proposed configuration of transverse reinforcement can provided improved ductility to the confined concrete compared to rectangular spiral reinforcement.

• Journal of the Korean Solar Energy Society
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• v.24 no.1
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• pp.47-52
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• 2004

An experimental investigation was performed to compare ice making characteristics of ice storage system with smooth and spiral tube. During the freezing processes in the shell and tube type ice storage tank with smooth tube, heat resistance of the ice layer caused a decrease in freezing rate. Also, the phenomena of bridging made the increasing rate of ice making less. In order to improve the ice making rate, spiral tube(pitch=6mm) was used in the present study. The ice making rate and the decreasing of bridging for the spiral tube were higher than those for the smooth tube.

• Journal of Magnetics
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• v.18 no.2
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• pp.111-116
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• 2013

This paper presents a characteristic analysis method of a permanent magnet type transverse flux linear motor (TFLM) with spiral cores. The spiral cores are used as the mover cores in order to make 3-dimensional (3-D) magnetic flux paths at the TFLM which have 3-D magnetic flux flows. The 3-D Equivalent Magnetic Circuit Network Method is used to analyse the magnetic characteristics of the machine, and an imaginary part, 'flux barrier,' is introduced to consider the spiral core characteristic. Magnetic parameters such as flux, inductance, and thrust are calculated from the analysis results. The computed thrust forces are compared to measured values to confirm the accuracy of the analysis.

• The Bulletin of The Korean Astronomical Society
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• v.44 no.1
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• pp.79.3-79.3
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• 2019

Observational evidence for intrinsic galaxy alignments in isolated spiral pairs is presented. From the catalog of the galaxy groups identified by Tempel et al. in the flux-limited galaxy sample of the Sloan Digital Sky Survey Data Release 10, we select those groups consisting only of two spiral galaxies as isolated spiral pairs and investigate if and how strongly the spin axes of their two spiral members are aligned with each other. We detect a clear signal of intrinsic spin alignment in isolated spiral pairs, which leads to the rejection of the null hypothesis at the 99.9999% confidence level via the Rayleigh test. It is also found that those isolated pairs comprising two early-type spiral galaxies exhibit the strongest signal of intrinsic spin alignment and that the strength of the alignment signal depends on the angular separation distance as well as on the luminosity ratio of the member galaxies. Using the dark matter halos consisting of only two subhalos resolved in the EAGLE hydrodynamic simulations, we repeat the same analysis but fail to find any alignment tendency between the spin angular momentum vectors of the stellar components of the subhalos, which is in tension with the observational result. Several possible sources of this apparent inconsistency between the observational and the numerical results are discussed.

• The Bulletin of The Korean Astronomical Society
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• v.44 no.1
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• pp.35.2-35.2
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• 2019

Observational evidence for intrinsic galaxy alignments in isolated spiral pairs is presented. From the catalog of the galaxy groups identified by Tempel et al. in the flux-limited galaxy sample of the Sloan Digital Sky Survey Data Release 10, we select those groups consisting only of two spiral galaxies as isolated spiral pairs and investigate if and how strongly the spin axes of their two spiral members are aligned with each other. We detect a clear signal of intrinsic spin alignment in isolated spiral pairs, which leads to the rejection of the null hypothesis at the 99.9999% confidence level via the Rayleigh test. It is also found that those isolated pairs comprising two early-type spiral galaxies exhibit the strongest signal of intrinsic spin alignment and that the strength of the alignment signal depends on the angular separation distance as well as on the luminosity ratio of the member galaxies. Using the dark matter halos consisting of only two subhalos resolved in the EAGLE hydrodynamic simulations, we repeat the same analysis but fail to find any alignment tendency between the spin angular momentum vectors of the stellar components of the subhalos, which is in tension with the observational result. Several possible sources of this apparent inconsistency between the observational and the numerical results are discussed.

• Journal of the Korean Vacuum Society
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• v.8 no.4A
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• pp.461-464
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• 1999

Planar type thin film inductors have a potential for the application of miniaturized DC-DC converters. For those high current applications, the magnetic film with high current capability is required. The current capability of magnetic films is mainly determined from high saturation magnetization (4$\piM_s$) as well as large anisotropy field $(H_k)$. We fabricated a double rectangular spiral thin film inductor which consist of magnetic layer, coil and insulator. Highest inductance values as well as best frequency characteristics can be obtained from 5 MHz and quality factor exhibit about 7.