• Journal of computational fluids engineering
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• v.14 no.3
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• pp.16-24
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• 2009

Numerical simulation has been carried out to investigate the influence of radial temperature gradient on the Circular-Couette flow. Varying the Grashof number, we study the detailed flow and temperature fields. The current numerical results show good agreement with the analytical and experimental results currently available. It turns out that spiral vortices are generated by increasing temperature gradient. We classify the flow patterns for various Grashof number based on the characteristics of flow fields and spiral vortices. The correlation between Richardson number with wave number shows that the spiral angle and size of spiral vortices increase with increasing Richardson number.

• Transactions of Materials Processing
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• v.17 no.1
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• pp.5-8
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• 2008

As the semi-solid forming technology has a lot of advantages compared to the die casting, squeeze casting and hot/cold forging, it has been studied actively. This paper focuses on the thixoforging of the rheological materials fabricated by the spiral mechanical stirring equipment with A356 casting aluminum alloy and A6061 wrought aluminum alloy. Formability tests of rheological materials fabricated by spiral mechanical stirring were carried out and the microstructures of forged sample were observed. After thixoforging experiment, the heat-treated conditions of forged samples are investigated to improve the mechanical properties. These results are able to suggest the possibility of commercialization for rheological materials fabricated by spiral mechanical stirring.

• 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.

• Proceedings of the KIEE Conference
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• 2000.07d
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• pp.3207-3209
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• 2000

X-ray CT(Computed Tomography) has been a good modality for non-invasive diagnosis and recently, Conventional CT has been replaced rapidly with Spiral CT in recent. In X-ray CT, spiral scanning has various advantages such as better image quality, reduced scan time (in a single breath-hold), a lower x-ray dose. But, it requires very fast and high performance image processing system to reconstruct slice images from spiral scanning. This paper describes the fast image reconstruction techniques with filtered back projection from the viewpoints of fast algorithm as well as hardware implementation for real-time imaging.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.11
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• pp.1967-1971
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• 2007

In this paper, we verified basic forms and equivalent circuits of spiral inductors and various kinds of parasitics of equivalent circuits by using HFSS and Nexxim program that were 3-D EM analysis tools, and fabrication on-chip spiral inductors using Hynix's 0.25um 1-poly and 5-metal CMOS process. Comparing with PGS(patterned ground shield) and NPGS(non patterned ground shield) of spiral inductors of 3.5 turn, 4.5 turn and 5.5 turn, etc, the application of PGS could improve maximum Q value by 8-12%.

• Proceedings of the KIEE Conference
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• 2006.07c
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• pp.1301-1302
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• 2006

In this paper, embedded spiral inductors are investigated into the PCB substrate for low cost RF SOP applications. The spiral inductors designed with geometrical variations were simulated, fabricated, measured, and characterized by using 3D EM simulator, 8 layered PCB standard process and HP 8510B network analyzer (or verifying their applicability. The fabricated embedded spiral inductor has inductance of 9.4 nH at 800MHz, maximum quality factor of 64.8 at 1.09GHz and self resonant frequency of 3.93GHz, respectively. As the measured inductances and quality factors are well matched with simulated ones. PCB embedded spiral inductors are promising for advanced electronic systems with various functionality, low cost, small size and volume.

• Asian Journal for Public Opinion Research
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• v.10 no.3
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• pp.149-177
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• 2022

This study analyzes how inoculation affects the spiral of silence. Inoculation could be a beneficial tool in a democracy as it elevates citizens' resistance to attitude change "forced" by "the winning opinion" in the spiral of silence on a certain controversial issue. The study examines essential variables combined with the theories of inoculation and spiral of silence, such as resistance to counter-attitudinal attack, fear of isolation, and issue-involvement. A two-wave field experiment was employed to assess the formation of public opinion on Taiwan's political future with the People's Republic of China. Results support that inoculation enhanced people's resistance to attitude change and decreased their fear of isolation. Individuals who are more issue-involved were also shown to be more affected by inoculation, which allowed them to resist attitude change. The decreased fear of isolation, coupled with more issue involvement, might elevate people's willingness to speak out in public. More political discussions regarding an important public issue might be expected in a democracy.

• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.7
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• pp.1381-1390
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• 1992

This paper presents a dynamic characteristics of flow induced vibration of circular cylinder set with inclined angle against flow direction. The effect of the cylinder bounded by spiral fin and wire on the damping of flow induced vibration is investigated, i.e., inclined angle, spiral pitch angle and number of spiral thread are studied. As the results, the cylinder with spiral fin is most effective for the damping. Also the cylinder bounded by pitch angle 50.deg. and 2 spiral thread is most effective.

• Journal of the Korean Society for Nondestructive Testing
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• v.28 no.5
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• pp.416-420
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• 2008

In EMAT field, spiral RF coils are much more widely used when compared with solenoid coils. In the field of the magnetostrictive strip transducers for long range ultrasonic testing of cylindrical structures, however, solenoid coils has been used. This seems to be attributed to the difficulty in fabricating low frequency (i.e., large size) spiral coils. In this paper, we describe a method for fabricating spiral coil magnetostrictive strip guided wave transducers from FFC (flexible flat cable). It is demonstrated through a comparison experiment that the spiral coil transducer has much superior performance (sensitivity, SNR, and guided wave direction control capability) than the previous transducer with solenoid coils.

• Journal of Chest Surgery
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• v.30 no.3
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• pp.344-347
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• 1997

A 49-year-old female patient who had obstruction of superior vents cave(SVC) with SVC syndrome was successfully managed by bypass operation of superior vents cava with spiral vein graft. A composite spiral vein graft was placed between the right innominate vein and the right atrium to bypass the occluded SVC. The graft was constructed from the patient's own saphenous vein, which was split longitudinally and wrapped around a stent in spiral fashion and the edges of the vein were sutured together to form a large autogenous conduit. The patient was relieved o SVC obstructive symtoms and signs and discharged 21 days postoperatively without any complication.