• Journal of Hydrogen and New Energy
• /
• v.31 no.2
• /
• pp.194-201
• /
• 2020

Recently, Type 2 high-pressure hydrogen storage tank is studied due to fast defect detection, easy manufacturing, and cost efficiency. Moreover, the dry winding a high-strength metal wire will make increased economic efficiency compare with the wet winding method and the carbon/glass fiber winding method. In this study, a theoretical study on the dry winding of a Type 2 high pressure hydrogen tank using a metal wire was done, and the equations of the total stress on the aligned and the staggered winding for the hoop winding were derived, and the following results were obtained by using these equations. As the diameter of the metal wire, the number of winding layers, and the outer diameter of the liner increase, the maximum stress decreases, but the difference between the maximum stress occurring in the aligned winding and the staggered winding increases. As the pressure increases, the thickness of the winding layer increases, but as the strength of the metal wire increases, the thickness of the winding layer decreases. In addition, regardless of the strength of the metal wire, the thickness of the winding layer of the staggered winding was about 13.4% thinner than that of the aligned winding.

• Journal of the Korean Vacuum Society
• /
• v.9 no.3
• /
• pp.207-215
• /
• 2000

Al films on cold-rolled steel sheet have been prepared by vacuum evaporation and arc-induced ion plating, respectively, and the evaporation rate and vapor distribution (thickness distribution over the substrate) have been investigated according to deposition conditions. The arc-induced ion plating (AIIP) method have been employed, which makes use of arc-like discharge current induced by ionization electrode located near the evaporation source. The AIIP takes advantage of high ionization rate compared with conventional ion plating, and can be carried out at low pressure of less than $10^{-4}$ torr. Very high evaporation rate of more than 2.0 mu\textrm{m}$/min could be achieved for Al evaporation using alumina liner by electron beam evaporation. The geometry factor n for the $cos^{n/\phi}$ vapor distribution, which affects the thickness distribution of films at the substrate turned out to be around 1 for vacuum evaporation, while it features around 2 or higher for ion plating. For the ion plated films, it has been found that the ionization condition and substrate bias are the main parameters to affect the thickness distribution of the films.

• The Journal of Korean Academy of Prosthodontics
• /
• v.47 no.2
• /
• pp.199-205
• /
• 2009

Purpose: The purpose of this research was to evaluate the shear bond strength between zirconia core and veneer ceramic after surface treatment. Material and methods: Zirconia cores(N=40, n=10, $10mm{\times}10mm{\times}3mm$) were fabricated according to the manufacturers' instructions and ultrasonically cleaned. The veneering ceramics(thickness 3 mm) were built and fired onto the zirconia core materials. Four groups of specimens with different surface treatment were prepared. Group I: without any pre-treatment, Group II: treated with sandblasting, Group III: treated with liner, Group IV: treated with sandblasting and liner. The shear bond strength was tested in a universal testing machine. Data were compared with an ANOVA and $Scheff{\acute{e}}$ post hoc test(P=.05). Results: The shear bond strength of group VI was significantly higher than the other groups. Conclusion: Both mechanically and chemically treated simultaneously on zirconia core surface influenced the shear bond strength between the core and veneering ceramic in all-ceramic systems.

• Tribology and Lubricants
• /
• v.32 no.1
• /
• pp.24-31
• /
• 2016

In this paper hydrodynamic lubrication analysis is carried out to investigate the effects of groove location on the lubrication performance of a piston and cylinder system in a linear compressor. The rectangle shaped grooves having a constant groove depth and width are applied on the lubrication area of the piston. The Universal Reynolds equation is used to calculate the oil film pressure, and the Elrod algorithm with the finite different method is used to solve the governing equation. The JFO boundary condition is applied to predict cavitation regions. Transient analysis for different locations of the grooves on the piston is carried out using the typical operating condition of the linear compressor in order to estimate the variations of frictional power losses and minimum film thicknesses. When the grooves are applied on the lubrication area, both the frictional power loss and the minimum film thickness decrease. The frictional power loss can be reduced effectively, while maintaining a minimum film thickness to enable the piston operation without direct contact with the cylinder surface, by means of choosing a proper location of the grooves. The optimum location of the grooves to improve a lubrication performance depends on the operation condition or the system requirements specification.

• JSTS:Journal of Semiconductor Technology and Science
• /
• v.14 no.5
• /
• pp.649-657
• /
• 2014

In this study, the effects of the frequency-dependent characteristics of through-silicon vias (TSVs) on the performance of 3D ICs are examined by evaluating a typical interconnection structure, which is composed of 32-nm CMOS inverter drivers and receivers connected through TSVs. The frequency-domain model of TSVs is extracted in S-parameter from a 3D electromagnetic (EM) method, where the dimensional variation effect of TSVs can be accurately considered for a comprehensive parameter sweep simulation. A parametric analysis shows that the propagation delay increases with the diameter and height of the TSVs but decreases with the pitch and liner thickness. We also investigate the crosstalk effect between TSVs by testing different signaling conditions. From the simulations, the worst signal integrity is observed when the signal experiences a simultaneously coupled transition in the opposite direction from the aggressor lines. Simulation results for nine-TSV bundles having regular and staggered patterns reveal that the proposed method can characterize TSV-based 3D interconnections of any dimensions and patterns.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.28 no.9
• /
• pp.1384-1390
• /
• 2004

The full containment Liquefied Natural Gas(LNG) storage tank is based on a double liquid container concept : two separate containers, one within the other, are capable of containing the LNG. The outer concrete tank provides comer protection(secondary containment) to withstand and safely contain any spill from the inner tank. The comer protection is installed on inside corner surface of outer concrete tank. Because of high and complex stresses, corner protection is designed by ASME section ⅧI Div. 2, Appendix 4 on behalf of API 620 which is main design code for LNG tank. Design guidelines to determine design factors such as liner thickness and knuckle radius are not well understood because Appendix 4 is the design method not based on equation but FEM. Recently, the volume of LNG tank shows a tendency to increase. So it is necessary to set up the design guidelines to cope with change of LNG tank capacity and height/diameter ratio. In this paper, optimum design of corner protection was performed and the design guidelines were suggested by the results of FEM for LNG tanks which have different capacities and height/diameter ratio.

• Journal of the korean society of oceanography
• /
• v.38 no.4
• /
• pp.166-172
• /
• 2003

Multi­Sensor Core Logger (MSCL) is a useful system for logging the physical properties (compressional wave velocity, wet bulk density, fractional porosity, magnetic susceptibility and/or natural gamma radiation) of marine sediments through scanning of whole cores in a nondestructive fashion. But MSCL has a number of problems that can lead to spurious results depending on the various factors such as core slumping, gas expansion, mechanical stretching, and the thickness variation of core liner and sediment. For the verification of MSCL data, compressional wave velocity, wet bulk density, and porosity were measured on discrete samples by Hamilton Frame and Gravimetric method, respectively. Acoustic impedance was also calculated. Physical property data (velocity, wet bulk density, and impedance) logged by MSCL were slightly larger than those of discrete sample, and porosity is reverse. Average difference between MSCL and discrete sample at both sites is relatively small such as 22­24 m/s in velocity, $0.02­-0.08\;g/\textrm{cm}^3$ in wet bulk density, and 2.5­2.7% in porosity. The values also show systematic variation with sediment depth. A variety of factors are probably responsible for the differences including instrument error, various measurement method, sediment disturbance, and accuracy of calibration. Therefore, MSCL can be effectively used to collect physical property data with high resolution and quality, if the calibration is accurately completed.

• The Journal of Korean Physical Therapy
• /
• v.16 no.3
• /
• pp.50-64
• /
• 2004

The studies have been designed to evaluate the effect of wound healing of pulsed ultrasound and chitosan application in diabetic incisive wound of rats. Mild diabetes mellitus was induced in rat used 30 mg/kg streptozotocin. Full thickness skin incision was made on the backs of Sprague-Dawley rats. We used 72 Sprague-Dawley rats which were divided into 4 groups; the subjects were divided into group of 6 rats each 3, 6, and 15 days. The results were summarized as follows; The rate of wound length of pulsed ultrasound with chitosan application groups more decreased than only pulsed ultrasound treatment group. The density of inflammatory cells in the experimental groups was more significantly decreased than diabetic control group(p<0.05). Historically, in the ultrasound with chitosan application groups, reepithelized epithelium was thicker and the collagen fiber were organized in a liner manner and connective tissue was matured faster those of the diabetic control group(p<0.05). From the conclusions above, in this study application of pulsed ultrasound and chitosan can be an effective way of promotion of wound healing in diabetic model.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.21 no.5
• /
• pp.255-264
• /
• 2017

Dynamic numerical simulation of pile-supported slab track system embedded in a soft soil and embankment was performed. 3D model was formulated in a time domain to consider the non-linearity of soil by utilizing FLAC 3D, which is a finite difference method program. Soil non-linearity was simulated by adopting the hysteric damping model and liner elements, which could consider soil-pile interface. The long period seismic loads, Hachinohe type strong motions, were applied for estimating seismic respose of the system, Parametric study was carried out by changing subsoil layer profile, embankment height and seismic loading conditions. The most of horizontal permanent displacement was initiated by slope failure. Increase of the embedded height and thickness of the soft soil layer leads increase of member forces of PHC piles; bending moment, and axial force. Finally, basic guidelines for designing pile-supported slab track system under seismic loading are recommended based on the analysis results.

• Journal of Aerospace System Engineering
• /
• v.17 no.6
• /
• pp.127-132
• /
• 2023

In this study, designing of a Type 4 pressure vessel using the filament winding method was conducted. In order to prevent leakage in consideration of the design of the hydrogen storage tank, a liner was designed by applying high-density polyethylene (HDPE), and the composite structure was designed by stacking carbon/epoxy in the hoop and helical directions. As a theoretical approach, the angle of the helical fiber and fiber thickness of each hoop and helix were designed. The safety of the design was verified using the commercial software ANSYS.