• Journal of the Korean Society for Precision Engineering
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• v.20 no.6
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• pp.214-221
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• 2003

Tension mask assembly is positioned right behind the glass-made front panels of CRT type display devices. The frame-supported thin metal sheet contains numerous slits, through which electron beams are focused to enhance definition. Pretension is imposed on the masks, especially for enlarged flat screens, in order to avoid vibration due to acoustic or mechanical impact. High temperature assembly process subsequent to pretensioning, however, degenerates the creep resistance of common mask materials, and if tensile stress is high enough, tension on the mask may be loosened substantially due to creep deformation. In this study, the assembly is modeled as a combined structure of beams and wire array, and a numerical simulation is attempted for pretensioning followed by high temperature process. According to a model study, small amount of creep strain is likely to be generated, but its adverse influence is not negligible. Some structural modification measures to reduce the creep-induced tension loosening are proposed and evaluated. Also, optimal configuration of frame structure is sought for, which maintains high tension of masks and minimizes the possible creep of frame simultaneously.

• Journal of Ocean Engineering and Technology
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• v.24 no.1
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• pp.10-19
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• 2010

ANSYS multi-physics software was applied to solve the coupled dynamic problem related to a full-scale TLP foundation for floating wind turbines. In this coupled dynamics simulation, the forced oscillation imposed on the tethers' top resulting from the sway of the wind turbine platform and the self-excited vortex-induced vibration (VIV) along the tether span have been taken into account. The stability of this tensioned tether system has been validated in the form of separate static and dynamic analyses. The dynamic characteristics of the tensioned tether linked to the floating wind turbine were analyzed by the resultant modal form and its corresponding vortex shedding pattern. The calculated result shows that even a slight forced oscillation imposed on the tethers' top leads to the VIV amplification and enhances the risk of instability in the case of low pretension. It is also found that the "synchronization" would be aggravated when the top tension decreases and the "2P" vortex shedding mode takes place. The increased top tension imposed on the tethers contributes to the stability of the tensioned legs by diminishing the oscillation amplitude markedly.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.2 no.2
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• pp.173-178
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• 1969

Few reports have been written regarding the measurement of stern trawler warp tension under conditions of a full catch. This report compares the tension imposed on the warps at the time the boat begins to tow the net and the tension at the time the cod end is filled with a large quantity of fish. The structure of the otter boards and trawl net used for the experiment was the same types as used by Koyama, Sakurai, and Sumikawa (1968). The warp tension was measured with a load cell tension meter. 3) This meter continuously records the tension on a pen oscillograph. The net towing speed was measured with the CM-lA type current meter, Toho Dentan Co. Ltd., Japan. The data collected in the experiment are shown in Table 1. This table indicates that shooting No. 2 and No. 11 show a large catch volume, and the types of fish caught are shown in Table 2. The tension meter recordings when the boat began to tow the net and when the cod end was filled with a large quantity are shown in Fig. 1 and Fig. 2. It is indicated that the barracouta Thyrsites atun (EUPHRASEN) causes little tension difference between the time before they enter the net and the time after they enter the net before hauling. Other types of fish influence tension similarly. According to these results, the warp tension measurements as recorded on a big stern trawler are more influenced by rough sea wave action than by the volume of fish caught.

• Korea-Australia Rheology Journal
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• v.12 no.2
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• pp.107-117
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• 2000

Prediction of the product shape in sheet casting process is performed from the numerical simulation. A three-dimensional finite element method is used to investigate the flow behavior and to examine the effects of processing conditions on the sheet produced. Effects of inertia, gravity, surface tension and non-Newtonian viscosity on the thickness profile of the sheet are considered since the edge bead and the flow patterns in the chill roll region have great influence on the quality of the products. In the numerical simulation with free surface flows, the spine method is adopted to update the free surface, and the force-free boundary condition is imposed along the take-up plane to avoid severe singularity problems existing at the take-up plane. From the numerical results of steady isothermal flows of a generalized Newtonian fluid, it is shown that the draw ratio plays a major role in predicting the shape of the final sheet produced and the surface tension has considerable effect on the bead thickness ratio and the bead width fraction, while shear-thinning and/or tension-thickening viscosity affect the degree of neck-in.

• International Journal of Aeronautical and Space Sciences
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• v.9 no.1
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• pp.137-146
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• 2008

Proper amount of entrained air and nip force should be also considered to minimize ballooning phenomenon since tight contact between a roller and web is required. In this paper, various web materials, PET(Polyester) and OPP(Oriented Poly Propylene) have been selected and investigated to satisfy high-speed printing requirement. Several web speeds, web tensions, and temperature conditions are imposed on each web materials and the pressure and gap profiles as well as nip force have been calculated. Increase of both the winding roller radius and the incoming wrap angle is considered under proper taper tension at 500 m/min of rewinding roller. By solving coupled Reynolds equation and web deflection equation simultaneously, the fluid-structure interaction process has been developed and is applied to the rewinding roller to investigate the ballooning phenomenon which causes guiding problems in high-speed printing performance conditions. By adjusting the linear taper tension, stress distribution between rewinding webs can be remarkably reduced and stable pressure and gap profile with ignorable ballooning phenomenon have been found.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2002.05a
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• pp.29-32
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• 2002

The mechanical joining process of a sheet metal pair has been developed in order to replace the resistance spot welding process in case that joining of mechanically unweldable materials and coated sheet metals with different thickness are needed. Form-joining or clinching, a kind of mechanical joining process, is defined as joining process of a sheet metal pair by geometric constraint imposed by plastic deformation of workpieces without any additive part. It has been reported that the joining strength by commercial form-joining apparatus is 50∼70 percent of that by resistance spot welding. Therefore, a two-step form-joining process with a secondary punch is proposed. The device is designed to improve the joining strength by increasing the geometric constraint of the deformed shape by combining a primary punch, a secondary punch and a female die. In order to verify the improved joining strength by the designed process, the tensile-shear strength, the peel-tension strength and the asymmetric peel-tension strength are compared with those by the TOX process and resistance spot welding.

• Industry Promotion Research
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• v.8 no.3
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• pp.111-123
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• 2023

The purpose of this study is to examine the structural relationship and confirm the effect of labor as a civil servant in charge of civil affairs how excessive social support and delayed tension affect psychological exhaustion. The results are as follow. First, as a result of analyzing the structural relationship between Emotional Labor, social support, perceived stress, and psychological exhaustion of Civil Affairs Officials, Emotional Labor of civil Civil Affairs Officials has a positive effect on social support, perceived stress, and psychological exhaustion. Social support had a significant negative effect on psychological exhaustion. Perceived stress was found to have a positive effect on psychological exhaustion. Second, as a result of soldering the labor effect of social support and involved tension in the relationship between labor and psychological burnout of public officials in charge of financial resources, a partial mediating effect was confirmed.The object should be used to first respond to and show the reinforcement of social support and the reduction of painted pressure, identified as labor variables, before farmers appear.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.9
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• pp.2162-2171
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• 1993

Geneal Structure optimization is utilized to minimize the weight of structures while satisfying constraints imposed on stress, displacements and natural frequencies, etc. Sandwich structures consist of inside core and outside face sheets. The selected sandwich structures are isotropic sandwich beams and isotropic sandwich plate. The face sheets are treated as membrane and assumed to carry only tensions, while the core is assumed to carry only transverse shear. The characteristic of the varying area are considered by adding the projected component of the tension to the transverse shear. The bending theory and energy method are adopted for analyzing sandwich beams and plates, respectively. In the optimization process, the cost function is the weight of a structure, and a deflection and stress constraints are considered. Design variable are thickness and tapering coefficients which determine the shape of a structure. An existing optimization code is used for solving the formulated problems.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.7 no.1
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• pp.27-40
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• 1997

The heat in Czochralski method is transfered by all transport mechanisms such as convection, conduction and radiation and convection is caused by the temperature difference in the molden pool, the rotations of crystal or crucible and the difference of surface tension. This study delvelops the simulation model of Czochralski growth by using the finite difference method with fixed grids combined with new latent heat treatment model. The radiative heat transfer occured in the surfce of the system is treated by calculating the view factors among surface elements. The model shows that the flow is turbulent, therefore, turbulent modeling must be used to simulate the transport phenomena in the real system applied to 8" Si single crystal growth process. The effects of a cusp magnetic field imposed on the Czochralski silicon melt are studied by numerical analysis. The cusp magnetic field reduces the natural and forced convection due to the rotation of crystal and crucible very effectively. It is shown that the oxygen concentration distribution on the melt/crystal interface is sensitively controlled by the change of the magnetic field intensity. This provides an interesting way to tune the desired O concentration in the crystal during the crystal growing.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.31 no.5
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• pp.31-46
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• 1999

A drying paper strives to shrink due to the shrinkage of the individual paper fibres. Laboratory results show that a reduction of the shrinkage or an imposed stretch leads to a large increase in tensile stiffness and a large decrease in strain at break. In c cylinder drying section the water in the web is repeatedly heated on the drying cylinder and evaporated in the free draw. To evaluate the drying process regarding influence on paper properties these sub-processes, or drying phases, have to be studied separately. The effect of the conditions on the drying cylinder and on the VacRoll is investigated in pilot trails. Both the fabric tension on the drying cylinder and on the VacRoll reduces the shrinkage of the paper. The laboratory results are used as input to a numerical simulation of the conditions in the free draw. If the web width is increased or the length of the free draw is reduced the mean shrinkage of the paper web is reduced . However, the difference in shrinkage between the middle and the edge of the web is increased.