• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.1451_1452
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• 2009

Owing to the increasing number of intelligent homes(or called Smart home), the corresponding cost is much higher. Low voltage circuit breakers are widely used in the intelligent homes to interrupt fault current rapidly and to assure the reliability of the power supply. The distribution of magnetic field induced by arc current in the contact system of molded case circuit breaker depends on the shape, arrangement, and kinds of material of grids. This paper is focused on understanding the interrupting capability, more specifically of the grid and the arc runner, based on the shape of the contact system in the current MCCB. The magnetic driving force was calculated by using the flux densities induced by the arc current, which are obtained by three-dimensional finite element method. There is a need to assure that the optimum design required to analyze the electromagnetic forces of the contact system generated by current and the flux density be present. This is paper present our computational analysis on contact system in MCCB.

• The KSFM Journal of Fluid Machinery
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• v.18 no.5
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• pp.19-25
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• 2015

As a core component of a hydropower station, hydro turbines play a vital role in the integration of a power station. Research on the technology of hydro turbine is continuously increasing with the development of water electricity. On the basis of one-dimensional loss analysis, for three-dimension design, there are a lot of dimension of the internal flow passage shapes that are determined by experience. Therefore, the effect of the internal flow passage shapes on the performance and internal flow characteristics of a Francis hydro turbine model is investigated in this study. In this study, the small curvature of runner blade trailing edge shape is good for improving the efficiency of Francis turbine. The straight stay vane leading edge is good for suppressing the secondary flow. Moreover, suitable tongue passage shape and stay vane number improve the performance of the turbine considerably.

• International Journal of Fluid Machinery and Systems
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• v.2 no.4
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• pp.375-382
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• 2009

Hydraulic instability associated with pressure fluctuations is a serious problem in hydraulic machinery. Pressure fluctuations are usually a result of a strong vortex created in the centre of a flow at the outlet of a runner. At every radial turbine and also at every single regulating axial turbine, the draft tube vortex appears at part-load operating regimes. The consequences of the vortex developed in the draft tube are very unpleasant pressure pulsation, axial and radial forces and torque fluctuation as well as turbine structure vibration. The consequences of the vortex are transferred upstream and downstream with amplitude and frequency modulation in respect of the turbine operating regime, cavitation conditions and air admitted content. Numerical prediction of the vortex appearance in the design stage is a very important task. The amplitude of the pressure pulsation is different for each operating regime therefore the main goal of this research was to numerically predict pressure pulsation amplitude versus different guide vane openings and to compare the results with experimental ones. For the numerical flow analysis of a complete Francis turbine (FT), the computer code ANSYS-CFX11 has been used.

• Journal of Fashion Business
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• v.17 no.6
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• pp.88-97
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• 2013

'Smart Clothes', which incorporate topnotch digital technology into fashion, are a leading fashion runner in this digital era. The purpose of the study is to first help develop a practical design for outdoor backpacks which are equipped with eco-friendly solar cells that facilitate recharging diverse smart devices during outdoor activities; and, secondly, to offer some practical data from the actual appropriation tests that will be used for manufacturing such products. This trial study finds out how to conjoin some practical IT devices with fashion items and mainly focusses on designing outdoor backpacks which are loaded with solar cells for recharging electric devices, and, later, experiments on designed backpacks with some smart phones to see how it works. According to the desired purposes of backpacks, all the features can be adjusted and modified such as the kinds of solar cell panels, materials, sizes, positions of attachment, weights, etc. Smart Clothes are highly functional and fashionable items that satisfy both practical and emotional purposes, and are being actively developed to serve consumers. This study proves that Smart Clothes or Smart Wear will have practical uses for outdoor activities and will possibly lead our smart lifestyles.

• Design & Manufacturing
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• v.10 no.2
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• pp.50-54
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• 2016

In the semiconductor industry the final products were checked for several environments before sell the products. The burning test of memory and chip was implemented in reliability for all of parts. The memory and chip were developed to high density memory and high performance chip, so circuit design was also high integrated and the test bed was needed to be thin and fine pitch socket. LGA(Land Grid Array) IC socket with thin wall thickness was designed to satisfy this requirement. The LGA IC socket plastic part was manufacture by injection molding process, it was needed accuracy, stiffness and suit resin with high flowability. In this study, injection molding process analysis was executed for 2 and 4 cavities moldings with runner, gate and sprue. The warpage analysis was also implemented for further gate removal process. Through the analyses the total deformations of the moldings were predicted within maximum 0.05mm deformation. Finally in consideration of these results, 2 and 4 cavities molds were designed and made and tested in injection molding process.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.16 no.6
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• pp.137-144
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• 2002

Low voltage circuit breakers which interrupt rapidly and raise the reliability of power supply are widely used in power distribution systems. In the paper, it has been investigated how much interrupting capability is improved by correcting the shape of the contact system in molded case circuit breaker(below MCCB), especially arc runner. Prior to the interrupting testing, it is necessary for the optimum design to analyze electromagnetic forces on the contact system generated by current and flux density. This paper presents both our computational analysis and test results on contact system in MCCB.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.10a
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• pp.279-284
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• 2005

The casting defects that are caused by molten metal were cold shut formation, entrapment of air, gas, and inclusion. But the control of casting defects has been based on the experience of the foundry engineers. In this thesis, the computer simulation analyzed the flow of molten metal. The quantitative analyses which proposed the effective mold design was executed Flow patterns of 0.15-0.16m/s molten metal in 15 mm thin plate casting were investigated in order to optimize die-casting process. As increasing ingate velocity in thin plate casting, cold shot was decreased. The parameters of runner shape that affected on the optimized conditions that was calculated with simple equation were investigated. These die casting process control techniques of automobile valve body mid-plate have achieved good agreement with the experimental data of tensile strength, hardness test, and material structure photographies satisfactory results.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.7
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• pp.4411-4417
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• 2015

The proper design of the gate location for injection molding of plastic goods is obtained from three-dimensional injection molding analysis for various design alternatives. This paper is study on effect of gate location in injection molding. It have a decisive impact on productivity and quality of plastic goods. This objectives of this paper is to analysis effect of hot runner gate location for resin filling, weld line, injection pressure to manufacture of automobile air cleaner upper case with injection molding machine. Thus, to analysis these problems in this paper, location of gate are gave variety in 4 CASEs. In this paper, the CAE simulation considering each variations in location of gate is performed to predict the cause of faulty which appears in the injection molding process.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.1
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• pp.35-42
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• 2015

Injection molding is a high efficient manufacturing technology for producing plastic parts. On the other hand, the warpage of molded plastic parts is an ubiquitous problem in the injection molding process. The main objective of this study was to minimize the amount of warpage occurring in the injection molding process of a hopper of ATDPS made of crystalline polymer (PP) instead of amorphous polymer (ABS). The moldflow CAE simulation was conducted for the molding process of the hopper to clarify the injection moldability, shear rate, shear stress, warpage by changing the gate shape and the number of ribs installed on the top of the hopper flange. The wide gate shape of runner system and multiple rib installation were found to be useful for minimizing the warpage of the hopper. The validity of the CAE simulations was supported by the injection molding experiment for the optimized design case.

• Journal of Korea Foundry Society
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• v.37 no.1
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• pp.1-13
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• 2017

The purpose of this study is to increase the part recovery rate (to more than 70%) during the casting of a ductile cast iron turbo charger housing using a heater around the riser. Before creating a casting mold, various runner and riser systems were designed and analyzed with a casting simulation analysis tool. The design variables were the heater temperature, top insulation, riser location, riser diameter and the riser shape. During the feeding from the riser to the part, the reverse model was better than the forward model. When heating the riser (above $600^{\circ}C$), solidification of the riser was delayed and the feeding effect was suitable compared to that without heating. At a higher heating temperature, less solidification shrinkage and porosity were noted inside the part. On the basis of a casting simulation, eight molds were fabricated and casting experiments were conducted. According to the experimental conditions, external and internal defects were analyzed and mechanical properties were tested. The ultimate tensile strength and elongation outcome were correspondingly more than 540MPa and 5% after a heat treatment. In addition, a maximum part recovery rate of 86% was achieved in this study.