• Transactions of the Korean Society of Automotive Engineers
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• v.10 no.4
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• pp.149-157
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• 2002

This paper is to investigate collapse mechanisms of CFRP(Carbon Fiber Reinforced Plastics)composite tubes and to evaluate collapse characteristics on the change of interlaiminar number and ply orientation angle of outer under static and impact axial compression loads. When a CFRP composite tube is crushed, static/impact energy is consumed by friction between the loading plate and the splayed fronds of the tube, by fracture of the fibers, matrix and their interface. These are associated with the energy absorption capability. In general, CFRP tube with 6 interlaminar number(C-type), absorbed more energy than other tubes(A, B, D-types). The maximum collapse load seemed to increase as the interlaminar number of such tubes increases. The collapse mode depended upon orientation angle of outer of CFRP tubes and loading status(static/impact). Typical collapse modes of CFRP tubes are wedge collapse mode, splaying collapse mode and fragmentation collapse mode. The wedge collapse mode was shown in case of CFRP tubes with 0° orientation angle of outer under static and impact loadings. The splaying collapse mode was shown in only case of CFRP tubes with 90°orientation angle of outer under static loadings, however in Impact tests those were collapsed in fragmentation mode .

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.13 no.8
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• pp.674-681
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• 2001

An experiment is conducted to investigate the effect of the inclination angle on convective boiling heat transfer of a uniformly heated tube. The test section used is a stainless steel tube with10.7mm in inner diameter. The hating length is 3m and is heated directly by an AC current. The test fluid is R-113. Experiment are carried out with mass flow rates of 300, 500 and $700\;kg/m^{2}s$, and heat fluxes varying from 5 to 65 kW/$m^2$. The inclination angles of the tube are $0^{\circ},\;5^{\circ},\;11^{\circ}\;and\;25^{\circ}$. the circumferential temperature variation at low quality region and the location of dryout at high quality region are mainly observed. Circumferential anisothermality occurring at low mass flow rate and low quality conditions is gradually reduced with the increase in the inclination angle and finally disappears at the inclination angle of $25^{\circ}$. Critical quality where dryout is initiated is seriously influenced by the inclination angle. Wall temperature after critical quality is also affected by the inclination angle.

• Journal of Mechanical Science and Technology
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• v.19 no.12
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• pp.2296-2302
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• 2005

This study is focused on the comparison of heat transfer performance of two thermosyphons having 60 straight and helical internal grooves. Distilled water has been used as working fluid. Liquid fill charge ratio defined by the ratio of working fluid volume to total internal volume of thermosyphon, the inclination angle and operating temperature were used as experimental parameters. The heat flux and heat transfer coefficient are estimated from experimental results. The conclusions of this study may be summarized as follows; Liquid fill charge ratio, inclination angle and geometric shape of grooves were very important factors for the operation of thermosyphon. The optimum liquid fill charge ratio for the best heat flux were $30\%$. The heat transfer performance of helically grooved tube was higher than that of straight grooved tube in low inclination angle (less than $30^{\circ}$), but the results were opposite in high inclination angle (more than $30^{\circ}$). As far as optimum inclination angle concerns, range of $25^{\circ}\~30^{\circ}$ for a helically grooved tube and about $40^{\circ}$ for a straight grooved tube are suggested angles for the best results.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.12 no.7
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• pp.623-631
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• 2000

Effects of the taper angle and the angular velocity of a pulse tube on the enthalpy flow loss associated with the steady mass streaming were analysis by two-dimensional analysis of a pulse tube with variable cross-section. It was shown that the steady mass flux can lead to a large steady second-order temperature. The enthalpy flow loss associated with the steady mass streaming increases as the angular velocity increases. For a pulse tube where the viscous penetration depth is far thinner than the inner radius, the enthalpy flow loss can be significantly reduced by tapering the pulse tube since both the steady mass flux and the steady second-order temperature decrease as the taper angle increase.

• Transactions of Materials Processing
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• v.15 no.7 s.88
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• pp.512-517
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• 2006

In this paper, the cold extrusion process for internal spline forming using a thin and long tube has been analyzed by using a rigid plastic finite element code. The internal spline consists of 10 tooths. The cold extrusion process has been focused on the comparisions of load-stroke relation and filling states of the teeth according to design parameters. The design parameters involve extrusion ratio, extrusion angle and friction factor. The internal spline forming can cause the buckling and folding during the cold extrusion process because of using a thin and long tube. The optimum design parameters have been obtained through rigid-plastic finite elements analysis. The extrusion ratio and extrusion angle have great effects on the deformation characteristics of the cold extrusion process.

• Journal of Advanced Technology Convergence
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• v.2 no.1
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• pp.17-21
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• 2023

In this study, using an X-ray device (Drgem TS-CSP) and foot phantom (SFT-1556), the angle of the X-ray tube was changed to 30°, 35°, 40°, 45°, and 50°, and the image was evaluated by quantitative and qualitative evaluation. In the blind test, it was the highest at 4.34 points at 40°, and in the part calculation using the Image J program, the angle was the largest at 1750 at 50°. In addition, in the area evaluation excluding overlapping areas, the X-ray tube showed the largest value at 40° Therefore, it was found that the X-ray tube angle was suitable when the X-ray tube angle was 40° as a projection method for observing the calcaneus.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.17 no.7
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• pp.635-641
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• 2005

This study experimented to understand the effects of transporting ice slurry through elbow and inclined tube. And at this experiment it used propylene glycol-water solution and a diameter of about 2mm ice particle. The experiments were carried out under various conditions, with velocity of water solution at the entry ranging from 1.0 to 3.5 w/s and elbows and inclined tubes of 4 kinds angle with $30^{\circ},\;45^{\circ},\;90^{\circ}\;and\;180^{\circ}$. The pressure drop between the tube entry and exit were measured. According to angle of bending, the highest pressure drop was measured at $30^{\circ}$ elbow and the lowest pressure drop was measured at $90^{\circ}$ elbow, and there are only a little differences of pressure drop between $45^{\circ}$ elbow and $180^{\circ}$ elbow. According to angle of inclined tube, the highest pressure drop was measured at $90^{\circ}$ inclined tube and the pressure drop at $45^{\circ},\;30^{\circ},\;180^{\circ}$ inclined tubes were lower successively. The lowest pressure drop in elbows and inclined tubes was measured at velocity of $2.0\~2.5$ m/s and concentration of $10\;wt\%$.

• Solar Energy
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• v.19 no.3
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• pp.85-91
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• 1999

This study represented experimental research on the flat-plate solar collector. The heat performances were measured the tube array surface temperature by thermal-couple. The solar collector($W{\times}H$) of $580{\times}1100$, various tilt angles of 30, 45, 60 degree and the internal tube number of 4, 6, 8, 10(ea) were utilized in the present investigation. It is found that the thermal concentration is higher as the tilt angle become larger and the solar tubes are more and more. In this stuby obtained results of following: The array of tubes in collector has the best nice in that the number of tube is eight and the tilt angle is 60 degree. The collect energy by each tube array shown high value by increase the number of tubes and tilt angles. In addition to, the collect energy depends on by the tilt angle than the number of tube.

• Journal of radiological science and technology
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• v.43 no.6
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• pp.489-494
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• 2020

The Law method is observing the temporal bone. There are two types of methods: the double angle method, which manipulates the center ray angle of the tube twice, and the single angle method, which manipulates once. The purpose is to increase the reproducibility of the image by making vertical incidence by making an assistive device using a 3D printer. Two assistive devices with a wedge-shaped 8.5 × 10 × 2.3 cm, an inclined surface of 7.5 cm, and an inclination angle of 15° were fabricated. Assistive devices can be combined with each other in the form of grooves, and PLA (Poly Lactic Acid) is used as a material. In the first experiment, 10 examiners operated the tube 15° in the caudad direction and 15° in the anterior direction, and measured it with a protractor to conduct a reproducibility experiment. Second, two examiners acquired vertically incidence images using the existing law method and assistive devices, and measured the distance between each measurement point to evaluate the reproducibility. The tube center ray angle reproducibility experiment was not statistically significant, but the angle difference was up to 9° between examiners. The reproducibility experiment of radiographic images was not statistically significant with the conventional method, and the method using an assistive device was statistically significant. Therefore, regardless of skill level, an image capable of securing reproducibility, which is the advantage of vertical incidence, could be obtained.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2000.04a
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• pp.15-19
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• 2000

Recently Western countries are now beginning to use ACM (Advanced Composites Material), in the construction industry Compared with existing construction materials, ACM possesses many advantages such as light-weight, high-strength, corrosion resistant property. Among other fabrication process of ACM, pultrusion is one of the promising one for civil infrastructure application. In this paper, the structural characteristics of pultruded GFRP strip and structural members of angle and tube type were studied. For the strip, parametric studies of pultrusion process has been carried out. Considered parameters were volume fraction, temperature, pulling speed and fiber orientations. For the pultruded angle and tube, compression test and buckling analysis has been carried out. The results were compared with calculated values using coded formulae