• Transactions of Materials Processing
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• v.8 no.5
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• pp.507-519
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• 1999

An approach using the energy method has veen proposed for the analysis of cone spinning having the complicated deformation modes mixed by shear and normal deformation. In the proposed method, the corresponding solution is found through optimization of the total energy dissipation with respect to the parameters assumed by the velocity field defined as the variation of the length in longitudinal direction. The sheet blank is divided into three layers to consider the bending effect and the energy dissipated by shear deformation is superposed to the energy consumption due to normal deformation related with the shrinking deformation is superposed to the energy consumption due to normal deformation related with the shrinking deformation of axi-symmetric sheet element for the evaluation of total deformation energy. In order to check the validity of the proposed method, the complex spinning for making the conical cup is analyzed and the computed results are compared with the experimental results. In comparison of the computed results with existing experimental results,, the good agreement is obtained for the variation of outer radius and the distribution of thickness, and it has thus been shown that the present approach is applicable to the analysis of complex spinning.

• Journal of the Korean Ceramic Society
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• v.33 no.10
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• pp.1079-1088
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• 1996

Discontinuous ${\gamma}$-LiAlO2 fibers for fiber-reinforcing MCFC matrixes have been produced by the sol-gel process using the centrifugal spinning apparatus of the Rotary type. Gel fibers could be obtained through spinning of stable LiAlO2 complex polymetric sols under the optimum spinning conditions (hollow-disc rotating velocity 9000 rpm sol feeding rate of 4ml/min flowing N2 temperature of 4$0^{\circ}C$ and flowing N2 pressure of 4 bar). It was found that defect free and densified ${\gamma}$-LiAlO2 fibers with the relative density of 98% and the mean diameter of 4.7${\mu}{\textrm}{m}$ were prepared when the spinned fibers were heat-treated to 100$0^{\circ}C$ on the specified heating schedule. in particular the mean diameter and length of fibers could be controlled by the pressure of flowing N2 and the chopping-sieving method respectively.

• Transactions of Materials Processing
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• v.7 no.5
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• pp.489-495
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• 1998

Spinning is a chipless forming method for producing axially symmetric parts by using axial-radial motions of a spinning roller. This process has still some advantages in such a view point that a variety of complex shapes which can not be formed in a press can be easily spun at a low cost although it is one of the oldest forming methods for spinning mainly cookware parts for a long time. This study is to investigate the optimum roller path in order to obtain the maximum spinnability in producing cylindrical cups of Aluminum(A1050-H16) sheet metal. Working conditions applicable to any size of blank were predetermined through preliminary spinning tests. 9 types of roller path were proposed and experiments were carried out. The modified involute curve was shown to give the maximum drawing ration and more uniform quality of spun cups as compared with other results of this study. in addition thickness distribution and dimensional accuracy of spun cups were examined and discussed.

• Journal of Fashion Business
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• v.1 no.1
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• pp.43-52
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• 1997

The main purpose of this study was to examine the sectors of Korean textile complex based on various economic characteristics and performances. The sectors in the textile complex differed in many aspects. Man-made fiber industry showed capital-intensive characteristics even though most of the sectors in the textile complex were labor-intensive. Textile industry is composed of weaving and spinning, knitting, dyeing and finishing sectors and even within the textile industry, each sector had different characteristics from each others. Weaving and spinning sector seemed to require relatively high capital investment, while dyeing and finishing was very labor-intensive. Labor-intensive apparel industry has faced decrease in labor-productivity while wage has increased. Slow growth in labor productivity in Korean textile complex was shown to be a more problem than increase in wage or ratio of labor cost to value added. Apparel companies appeared to be in better financial states than the textile companies, even though the exports of apparel products have decreased in the 1990s. However, in overall the financial states of the Korean textile complex were not as strong as those of the other manufacturing sectors.

• Transactions of Materials Processing
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• v.21 no.6
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• pp.360-365
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• 2012

The aim of this study was to investigate the effects of forming depth on the deformation behavior of cup-like tubes made of AISI1020 steel in tube spinning process. Spinning process was performed on cup-like tubes, which had an inner diameter of 34mm and thicknesses of 7, 8.5 or 11.5mm. The forming depths achieved were 3, 4, and 5.5mm. The complex deformation behaviors occurring during the tube spinning process was explained using the experimental results. Also analyzed were the causes of the material buildup and the bulge defect of inner surface, observed on cross section of tubes. The relationship between tube spinning conditions and the height of bulge defect was examined. The results indicate that bulge defect is increased with a decrease of the forming depth. Moreover, a critical forming depth exists for preventing the generation of the bulge defect in the tube spinning process. The present results will be useful for future decisions of forming depths for successful tube spinning of cup-like tubes.

• The Journal of the Korea Contents Association
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• v.15 no.7
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• pp.591-600
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• 2015

Recently high interest in health and fitness has led to vibrant researches for the active fitness system to learn and enjoy the exercise program for oneself. In this paper, we design and implement the active spinning training system which enables user to have self-learning and experience of customized spinning training program by the biometric and movement information acquired from user's physiological signals. The proposed system provides the appropriate difficulty of spinning program which reflects the concordance rate of spinning dance gestures and the amount of exercising by analyzing the physical status of participant from his brain and pulse waves and recognizing the skeletal movement in real time. For the higher exercise effect, the system offers a virtual personal trainer to show the correct poses and controls the level of difficulty depending on the concordance rate of participant's motions. The experiment with various participants through the proposed system shows that it is able to help users in getting the available exercise effect in comparatively short time.

• Transactions of Materials Processing
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• v.32 no.5
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• pp.268-275
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• 2023

ISO 21029 cryogenic vessel is used to transport cryogenic fluids. High-manganese steel (High-Mn steel) is widely regarded as suitable for use at cryogenic temperatures. The conventional way of manufacturing an ellipsoidal vessel head involves incremental stretching, followed by a spinning process. In this study, an alternative method for forming an ellipsoidal vessel head was proposed. Finite element analysis (FEA) was used to theoretically examine the strain evolution during a multi-stage forming process, which involved progressive stretching, deep drawing, and spinning of High-Mn steel. The distribution of effective strain and strain components were analyzed at different regions of the formed part. The FEA results revealed that only normal strains were evident in the dished region of the vessel head due to the stretching process. However, the flange region experienced complex strain evolution during the subsequent deep drawing and spinning process.

• 한국전산유체공학회:학술대회논문집
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• 2008.03a
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• pp.367-373
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• 2008

Spinning detonations propagating in a circular tube were numerically investigated with a one-step irreversible reaction model governed by Arrhenius kinetics. Activation energy is used as parameter as 10, 20, 27 and 35, and the specific heat ratio and the heat release are fixed as 1.2 and 50. The time evolution of the simulation results was utilized to reveal the propagation mechanism of single-headed spinning detonation. The track angle of soot record on the tube wall was numerically reproduced with various levels of activation energy, and the simulated unique angle was the same as that of the previous reports. The maximum pressure histories of the shock front on the tube wall showed stable pitch at Ea=10, periodical unstable pitch at Ea=20 and 27 and unstable pitch consisting of stable, periodical unstable and weak modes at Ea=35, respectively. In the weak mode, there is no Mach leg on the shock front, where the pressure level is much lower than the other modes. The shock front shapes and the pressure profiles on the tube wall clarified the mechanisms of these stable and unstable modes. In the stable pitch at Ea=10, the maximum pressure history on the tube wall remained nearly constant, and the steady single Mach leg on the shock front rotated at a constant speed. The high and low frequency pressure oscillations appeared in the periodical unstable pitch at Ea=20 and 27 of the maximum pressure history. The high frequency was one cycle of a self-induced oscillation by generation and decay in complex Mach interaction due to the variation in intensity of the transverse wave behind the shock front. Eventually, sequential high frequency oscillations formed the low frequency behavior because the frequency behavior was not always the same for each cycle. In unstable pitch at Ea=35, there are stable, periodical unstable and weak modes in one cycle of the low frequency oscillation in the maximum pressure history, and the pressure amplitude of low frequency was much larger than the others. The pressure peak appeared after weak mode, and the stable, periodical unstable and weak modes were sequentially observed with pressure decay. A series of simulations of spinning detonations clarified that the unsteady mechanism behind the shock front depending on the activation energy.

• 한국전산유체공학회:학술대회논문집
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• 2008.10a
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• pp.367-373
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• 2008

Spinning detonations propagating in a circular tube were numerically investigated with a one-step irreversible reaction model governed by Arrhenius kinetics. Activation energy is used as parameter as 10, 20, 27 and 35, and the specific heat ratio and the heat release are fixed as 1.2 and 50. The time evolution of the simulation results was utilized to reveal the propagation mechanism of single-headed spinning detonation. The track angle of soot record on the tube wall was numerically reproduced with various levels of activation energy, and the simulated unique angle was the same as that of the previous reports. The maximum pressure histories of the shock front on the tube wall showed stable pitch at Ea=10, periodical unstable pitch at Ea=20 and 27 and unstable pitch consisting of stable, periodical unstable and weak modes at Ea=35, respectively. In the weak mode, there is no Mach leg on the shock front, where the pressure level is much lower than the other modes. The shock front shapes and the pressure profiles on the tube wall clarified the mechanisms of these stable and unstable modes. In the stable pitch at Ea=10, the maximum pressure history on the tube wall remained nearly constant, and the steady single Mach leg on the shock front rotated at a constant speed. The high and low frequency pressure oscillations appeared in the periodical unstable pitch at Ea=20 and 27 of the maximum pressure history. The high frequency was one cycle of a self-induced oscillation by generation and decay in complex Mach interaction due to the variation in intensity of the transverse wave behind the shock front. Eventually, sequential high frequency oscillations formed the low frequency behavior because the frequency behavior was not always the same for each cycle. In unstable pitch at Ea=35, there are stable, periodical unstable and weak modes in one cycle of the low frequency oscillation in the maximum pressure history, and the pressure amplitude of low frequency was much larger than the others. The pressure peak appeared after weak mode, and the stable, periodical unstable and weak modes were sequentially observed with pressure decay. A series of simulations of spinning detonations clarified that the unsteady mechanism behind the shock front depending on the activation energy.

• Proceedings of the Korean Fiber Society Conference
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• 1987.06b
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• pp.11-11
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• 1987

Among other poly(4,4'-terephthanilidealkylamide)s (PTAA's), poly (4,4'-terephthanilideadipamide) (PTAd) gave clear critical concentration curves. For PTAA's with methylene units more than 6, the critical concentration (C*) seemed to be beyond the solubility limit of H₂SO₄. Under shearing conditions, the nematic domains were easily oriented and stretched in the direction of shear , and a fibrillar structure resulted. At low frequencies, a monotollous reduction of loss tangent (tan) was observed as concentration increased. At high frequencies, however, tan was increased above C* again, and showed maximum at saturation concentration (Cs). With increasing temperature, viscosity of isotropic and anisotropic phases was normally decreased, while viscosity of biphases was increased. Plot of complex viscosity (If) against temperature based on rheological measurements exhibited a good correlation with phase diagram constructed by polarizing microscope observations. Rheological parameters suggested the optimum dope concentration of PTAd with inherent viscosity 2.02 at 30oc is in the vicinity of 19.2 wt%, which seemed to agree well with spinning experiments (around 19.4 wt%). In general, effects of spinning and annealing conditions on the mechanical properties of PTAA fibres were most pronounced in PTAd fibre spun from anisotropic spinning dope .