• Tribology and Lubricants
• /
• v.33 no.1
• /
• pp.1-8
• /
• 2017

Drag torque reduction in a wet clutch pack is a key aspect of the design process of the dual clutch transmission (DCT) system. In order to reduce the drag torque caused by lubricant shear resistance, recently developed wet clutch pack systems of DCT, as well as automatic transmission and other four-wheel drive (4WD) couplings, frequently utilize wavy wet clutch pads. Therefore, wavy shape of friction pad are made on the groove patterns like waffle pattern for the reduction of drag torque. Additionally, the groove patterns are designed with larger channels at several locations on the friction pad to facilitate faster outflow of lubricant. However, channel performance is a function of the waviness of the friction pad at the location of the particular channel. This is because the discharge sectional area varies according to the waviness amplitude at the location of the particular channel. The higher location of the additional channel on the friction pad results in a larger cross-sectional area, which allows for a larger flow discharge rate. This results in reduction of the drag torque caused by the shear resistance of DCTF, because of marginal volume fraction of fluid (VOF) in the space between the friction pad and separator. This study computes the VOF in the space between the friction pad and separator, the hydrodynamic pressure developed, and the shear resistance of friction torque, by using CFD software (FLUENT). In addition, the study investigates the dependence of these parameters on the location and waviness amplitude of the channel pattern on the friction pad. The paper presents design guidelines on the proper location of high waviness amplitude on wavy friction pads.

• Solar Energy
• /
• v.16 no.2
• /
• pp.39-47
• /
• 1996

The horizontal thermal storage tank with heat pipe which is suitable for the sensible heat storage system is able to store a hot water from the heat source such as heating pad efficiently and to supply a hot water to load rapidly. And arrangement of heating pad play an important role in thermal flow and thermal storage efficiency. In this experiments, number of heating pad is ranged from three, five and nine, and when there is no change on number of heating pad, arrangements are two types of concentration-type and dispersion-type. Strong entrainment take place in the case of concentration-type of heating pad, and rapid temperature rise(${\Delta}{\doteqdot}1.6{\sim}3.2^{\circ}C$) in the tank is obtainable on the concentration-type than dispersion-type. In the constant number of heating pad, the concentration-type has the higher efficiency with about $5{\sim}6%$ than the dispersion-type Therefore, concentration-type of heating pad is an efficient design in constant number of heating pad.

• Tribology and Lubricants
• /
• v.28 no.5
• /
• pp.197-202
• /
• 2012

In this study, with the purpose of fundamentally improving the unbalance response vibration of a large PRT motor-generator rotor by design, a performance improvement design analysis is carried-out by retrofitting tilting pad bearings, replacing the plain partial journal bearings that were originally applied for operation at a rated speed of 1,800 rpm. In this process, a goal of the design analysis is to obtain a design solution for maximizing the direct stiffness of the bearings while satisfying the key basic lubrication performance requirements such as the minimum lift-off speed and maximum oil-film temperature. The results show that with a careful design application of tilting pad journal bearings for operation at such a relatively low speed of 1,800 rpm, direct stiffness increment of the bearings by about two times can be effectively achieved. Prevention of pad unloading is also considered in the analysis. Moreover, the designs of elliptical and offset half journal bearings are also analyzed and reviewed.

• The Research Journal of the Costume Culture
• /
• v.30 no.3
• /
• pp.403-413
• /
• 2022

The purpose of this study was to develop a 3D mesh-type impact protection pad with excellent motion adaptability and functionality by applying 3D printing technology. The hexagonal 3D mesh, which constitutes the basic structure of the pad, comprises two types: small and large. The bridge connecting the basic units was designed as the I-type, V-type, IV-type, and VV-type. After evaluating the characteristics of the bridge, it was found that the V-type bridge had the highest flexibility and tensile elongation. The hip joint pad and knee pad were completed by combining the hexagonal 3D mesh structure with the optimal bridge design. The impact protection pad was printed using a fused deposition modeling-type 3D printer with a filament made of thermoplastic polyurethane material, and the protection pad's performance was evaluated. When an impact force of approximately 6,500N was applied to the pad, the force attenuation percentage was 78%, and when an impact force of approximately 8,000N was applied, the force attenuation percentage was 75%. Through these results, it was confirmed that the 3D-printed impact protection pad with a hexagonal 3D mesh structure connected by a V-shaped bridge developed in this study can adapt to changes in the body surface according to movement and provides excellent impact protection performance.

• Journal of the Korean Society of Industry Convergence
• /
• v.23 no.5
• /
• pp.843-852
• /
• 2020

Among the many packaging materials used in cushion packaging, there is a lack of optimum design for packaging trays and cushion pads used in pear packaging for export and domestic distribution. It causes over-packaging due to excessive material input, and can be solved by applying various parameters needed to optimize the design of the packaging tray and cushion pad considering the packaging material and the number of pears in the box. In the case of a cushion pad for pears, the economic efficiency of material and thickness should be considered. Therefore, it is possible to design a packaging tray and cushion pad depending on eco-friendly packaging materials (PLA, PET) used by applying appropriate design parameters. The static characteristics of the materials used for the packaging of pears were analyzed using FEA (finite element analysis) simulation technique to derive the optimal design parameters. In this study, we analyzed the contact stress and deformation of PET, PLA tray (0.1, 0.5 1.0, 1.5 and 2 mm) and PET foam (2.0, 3 .0 and 4.0 mm) with pears to derive appropriate cushion packaging design factors. The contact stress between the pear and PET foam pad placed on PLA, PET trays were simulated by FEA considering the bioyield strength (192.54±28 kPa) of the pears and safety factor (5) of packaging design, which is the criterion of damage to the pears. For the combination of PET tray and PET foam buffer pad, the thickness of the PET foam is at least 3 mm, the thickness of the PET foam is at least 1.0 mm, the thickness of the foam is at least 2 mm, and if the thickness of the PET tray is at least 1.5 mm, the thickness of the foam is at least 1 mm, suitable for the packaging design. In addition, for the combination of PLA tray and PET foam pad, the thickness of the PET foam was not less than 2 mm if the thickness of the PLA tray was 0.5 mm, and 1 mm or more if the thickness of the PLA tray was not less than 1.0 mm, the thickness of the PET foam was suitable for the packaging design.

• Journal of the Korea Safety Management & Science
• /
• v.17 no.2
• /
• pp.235-240
• /
• 2015

Using a progressive die of the multi-stage drawing product, It was experiments for the Influence of the Products Roundness on the die pad process Safety die model, obstacle countermeasure research safety die design When the die pad is independent structure, Sidewall thickness of the inside 2stage, 3stage, 4stage of the product is thicker, the thickness of the inside 1stage and the bottom is thinner. it was become unstable beacuse the inside 1stage related to the Products Roundness is thinner. When the die pad is Integrated structure, Sidewall thickness of the inside 1stage, 2stage of the product is thicker, and Sidewall 3stage and 4stage was a thin. it was become unstable beacuse the inside 3stage related to the Products Roundness is thinner. Therefore, The appropriate combination of and integrated independent is required for each process.

• Tribology and Lubricants
• /
• v.5 no.2
• /
• pp.77-82
• /
• 1989

The influences of ram pressure on the performances of tilting-pad journal bearings are investigated experimentally. The test rig consists of a single tilting-pad and a rotating journal. Film thicknesses and pressure distribution of the lubricating film are measured continuously for several values of coordinate of the pivot position and journal speed. The findings of the investigation are as follows: (]) According as the journal speed increases the ram pressure increases, maximum pressure decreases and the pivot position which maximize the minimum film thickness shifts toward the leading edge. (2) The ram pressure makes it possible to generate the converging wedge and the positive pressure between the pad and the journal even when the pad is supported at the points between the leading edge and the center of the pad. (3) The influence of the ram pressure on the performance of tilting pad bearings is significant and must be considered in the design of these bearings.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.27 no.6
• /
• pp.455-463
• /
• 2022

This study proposes a receiving pad identification coil for wireless charging of electric vehicles. The proposed coil identifies the shape of the receiving pad through magnetic coupling with the receiving pad. Therefore, the shape of the coil is designed to show the different magnetic properties of each receiving pad. The accuracy of this design is verified through finite element method simulation. Furthermore, the operation method of the secondary pad identification circuit is described, and the appropriate magnitude and length of the pulse voltage applied to this circuit for receiving pad identification are derived through simulation. The performance of the proposed identification coil set is verified by the experimental results.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
• /
• 1995.05a
• /
• pp.69-76
• /
• 1995

The horizontal thermal storage tank with heat pipe which is suitable for the sensible heat storage system is able to store a hot water from the heat source such as heating pad efficiently and to supply a hot water to load rapidly. Therefore Arrangement of heating pad affects thermal flow and thermal storage efficiency. So, if effective arrangement is decided for condition of constant number of heating pad, the more rapid thermal flow effect and higher thermal storage efficiency is obtainable by active heat transfer. In this experiments, number of heating pad is ranged from three, five and nine, and when number of heating pad is constant, arrangement are two types of concentration-type and dispersion-type. As a result, for the case of concentration-type of heating pad, strong entrainment take place in horizontal thermal storage tank with heat pipe by active heat transfer and in the constant number of heating pad, the concentration-type has the higher efficiency with about 5∼6% than the dispersion-type. Therefore, when heating pad is equipted to horizontal thermal storage tank with heat pipe, concentration-type of heating pad is an efficient design in constant number. of heating pad.

• The Journal of the Acoustical Society of Korea
• /
• v.39 no.4
• /
• pp.331-341
• /
• 2020

At liftoff, launch vehicles are subject to harmful acoustic loads due to the intense acoustic waves generated by propulsion systems. Because these waves can cause electronic and mechanical components of launch vehicles and payloads to fail, predicting and mitigating acoustic loads is an important design issue. This article presents the latest information about the generation of acoustic waves and the acoustic design methods applicable to the launch pad. The development of the Japanese Epsilon solid launcher is given as an example of the new methodology for launch pad design. Computational fluid dynamics together with 1/42 scale model testing were performed for this development. Effectiveness of the launch pad design to reduce acoustic loads was confirmed by the post-flight analysis.