• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.15 no.11
• /
• pp.889-894
• /
• 2003

The objectives of this study are to present a proper mathematical model for a thermoelectric cooler equipped with the spacer and to investigate the effect of its geometries by heat transfer analysis. In order to enhance the efficiency of the thermoelectric cooler, the spacer is inserted between TEM (thermoelectric module) and cold plate. The theoretical results show that the COP (coefficient of performance) increases nonlinearly as high as 0.63 with increasing the depth of spacer and the depth of TEM and with decreasing the area of insulator.

• Korean Journal of Human Ecology
• /
• v.24 no.2
• /
• pp.285-295
• /
• 2015

To identify optimized thermal properties of mold brassiere cup for improved thermal comfort during summer, we compared the thermal resistance and the water vapor permeability of Polyurethane (PU) foam, 3D spacer fabric and the two combined materials of the PU foam and the 3D spacer fabric. Four experimental mold brassieres were made of the materials for wearing test. Six women in their twenties evaluated the wearing sensation in the hot and humid environment. The changes in microclimate temperature and humidity while wearing test brassiere cups were measured. Results indicate that thermal resistance increased as more PU foam were combined, while the water vapor permeability was higher as the content of the 3D spacer fabric increased at thickness of 18mm and over. However, in the wear test, the PU foam brassiere was the most preferred in all ambient conditions due to its soft, flexible and smooth texture, despite its high thermal resistance and low water vapor permeability. This indicates that the textures of mold foams are more dominant properties than thermal properties for mold foams in determining the wear comfort of mold brassieres.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.33 no.3
• /
• pp.225-230
• /
• 2020

Recently, with the miniaturization of GIS, there is a need for the miniaturization of spacers as accessories. Miniaturized spacers make it difficult to secure adequate insulation distances, resulting in a more concentrated electric field at the triple junction of high-voltage (HV) conductor-insulator (spacer)-insulation gas (SF₆), which is a weakness in GIS. Therefore, by introducing a new concept design technology, functionally graded material (FGM), which is recently applied to various materials and parts industries, three-dimensional control of the dielectric constant distribution in a spacer can be expected to alleviate triple-junction electric field occupancy and improve insulation performance. In this study, we propose an optimized model using NSGA-II to optimize the permittivity distribution of FGM applied spacer.

• The Journal of Korean Academy of Prosthodontics
• /
• v.37 no.5
• /
• pp.640-650
• /
• 1999

As an optimal quality of the restorations, there should be a least amount of seating discrepancy between the casting and abutment teeth. However, high viscosity of the cementing medium and its resulting thickness may prevent complete seating of the restoration. The use of die spacing material provides adequate internal relief for the cementing medium. The purpose of this study is to compare the thickness of three commonly used die spacing materials. Materials and Methods: Stone plates were fabricated and divided into 12 sections to be painted with die spacers. Tru-Fit, Whip-Mix and Belle do St. Claire die spacer which are commonly used in dental practice were tested in this study. Each die spacers were painted layer by layer according to the manufacturer's recommendation. The average thickness of each die spacers were measured with light microscope(${\times}100$) and compared between them. Results and Conclusions. A silver-colored Tru-Fit die spacer has the lowest value of thickness without statistical significance comparing with a gold-colored Tru-Fit die spacer and a gray layer of Whip-Mix die spacer has the highest value of thickness without any statistical significance comparing with Belle de St. Claire die spacer. Three and four layers of Tru-Fit die spacer and two layers of Whip-Mix and Belle de St. Claire die spacers seem to be in the acceptable range of thickness of 25 to $45{\mu}m$ for optimal seating of the restorations. The standard experimental design and method should be fur thor evaluated for more consistent and objective results.

• Journal of the Korean Society of Clothing and Textiles
• /
• v.41 no.5
• /
• pp.939-949
• /
• 2017

This study uses 3D printing technology to design and fabricate a fall impact protection pad with a spacer fabric structure. The design of the pads consists of hexagonal three-dimensional units connected in a honey-comb shape; in addition, the unit consists of a surface layer and a spacer layer. Protect pads were designed as either a hexagonal type or diamond type according to the surface layer structure; subsequently, a spacer filament was also designed as the most basic I-shape type. Designed pads were printed using four types of flexible filaments to select suitable material for a fall impact protection pad. Impact protection performance and bending stiffness were evaluated for the eight type of pad outputs. As a result of the impact protection performance evaluation, when the force of 6,500N was applied, the force passed through the pad was in the range of 1,370-2,132N. FlexSolid$^{(R)}$ and Skinflex$^{TM}$ showed good protection performance and cubicon flexible filament showed the lowest protection. NinjaFlex$^{(R)}$ was found to be the most flexible in the bending stiffness evaluation.

• Proceedings of the KSME Conference
• /
• 2000.04a
• /
• pp.731-736
• /
• 2000

An optimal design method is adopted for a spacer grid in nuclear power plant. It is made of punched sheet metal process, functioning as springs and dimples supporting fuel rods. For stress analysis of the assembled fuel rod support, a typical cell out of the repeated pattern in the assembly is modeled using 4-node shell elements. A commercial code, ABAQUS, is used for detailed analysis of contacting phenomena with friction. For the optimization, design varibles are taken from geometric parameters representing the shape of the bent leaf spring part and mating contact region with fuel rod. Objective function is considered in relation to mechanical functions and durability. Maximum yon Mises stress is considered in relation to constrained contact stress.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.26 no.8
• /
• pp.1623-1630
• /
• 2002

Recently, much attention is imposed on the design of the fuel assemblies in the Pressurized Light Water Reactor (PWR). Spacer grid is one of the main structural components in a fuel assembly. It supports fuel rods, guides cooling water, and maintains a coolable geometry from the external impact loads. In this research, a new shape of the spacer grid is designed by the axiomatic approach. The Independence axiom is utilized for the design. For conceptual design, functional requirements (FRs) are defined and corresponding design parameters (DPs) are found to satisfy FRs in sequence. Overall configuration and shapes are determined in this process. Detail design is carried out based on the result of the axiomatic design. For the detail design, the system performances are evaluated by using linear and nonlinear finite element analysis. The dimensions are determined by optimization. Some commercial codes are utilized for the analysis and design.

• Proceedings of the KSME Conference
• /
• 2001.06c
• /
• pp.548-553
• /
• 2001

Recently, much attention is imposed on the design of the fuel assemblies in the Pressurized Light Water Reactor (PWR). Spacer grid is one of the main structural components in a fuel assembly. It supports fuel rods, guides cooling water and protects the system from the external impact loads. Various space grids have been proposed and new designs are also being created. In this research, a new spacer grid is designed by the axiomatic approach. The Independence Axiom is utilized for the design. For conceptual design, functional requirements (FRs) are defined and corresponding design parameters (DPs) are found to satisfy FRs in sequence. Overall configuration and shapes are determined in this process. Detail design is carried out based on the result of the axiomatic design. For the detail design, the system performances are evaluated by using linear and nonlinear finite element analysis. The dimensions are determined by optimization. Some commercial codes are utilized for the analysis and design.

• Journal of Welding and Joining
• /
• v.30 no.1
• /
• pp.59-63
• /
• 2012

The spacer grid is one of the main structural components in a fuel assembly. It supports fuel rods, guides cooling water and maintains geometry from external impact load and cyclic stress by the vibration of nuclear fuel rod, it is necessary to have sufficient strength against dynamic external load and fatigue strength. In this study, the mechanical properties and fatigue characteristics of laser beam welded zircaloy thin sheet are examined. The material used in this study is a zirconium alloy with 0.66 mm of thickness. The fatigue strength under cyclic load was evaluated at stress ratio R=0.1. S-N curves are presented with statistical testing method recommend by JSME- S002 and compared with S-N curves at R.T. and $315^{\circ}C$. As a result of the experimental approach, the design guide of fatigue strength is proposed and the results obtained from this study are expected to be useful data for spacer gird design.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.22 no.4
• /
• pp.219-224
• /
• 2010

Recycling issue for the construction wastes is gradually important to future society. Recently, a star screen has been developed to use for this purpose, however some modifications were needed to enhance the separation accuracy. The objective of study is to evaluate and predict separation ability by verifying the effect for the modified shapes of the screen part. Two analysis models of the screen part were established using commercial software ADAMS to simulate the dynamic interaction of waste particles. Results showed that spacer and gear shapes directly affected separation ability. The modified spacer shapes were much higher screening rate with comparison to default shape. Screening ability for the half number of gear type was greater than other types. Therefore, modification of the design of screen part will be required to achieve better separation ability.