• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.20 no.3
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• pp.350-356
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• 2011

In this paper, we proposed the automatic cutting mechanism of the perforation pipes in an automobile muffler. This cutting mechanism makes continuous work possible, because it performs the batch work via the sequential operation of loading, feeding, cutting, and discharging. The proposed cutting mechanism consists of the frame unit, escape unit, turning unit, feeding unit, vision system, clamping unit, spindle/cutting unit and cooling unit. And, these mechanisms have been modularized through mechanical, dynamical and structural optimized design using the SMO (SimDesigner Motion) analysis module. Also, the virtual prototype was carried out using the 3-D CAD program. The cutting process cycle is performed in the order of loading, vision processing, feeding, clamping, cutting and discharging. And the cycle time for cutting one piece was designed to be completed in four seconds.

• Journal of Electrical Engineering and Technology
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• v.13 no.3
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• pp.1138-1146
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• 2018

Performance comparisons of switched reluctance motor for cooling fan application are dealt in this paper. Conventional and novel segmental type motors with the same dimension are compared. The conventional 12/8 type is very popular and used widely. The structure of segmental rotor type motor is constructed from a series of discrete segments, and the stator is constructed from two types of stator poles: exciting and auxiliary poles. This type of motor has short flux path and no flux reversal in the stator. The auxiliary poles are not wound by the windings and only provide the flux return path. Compared with conventional SRM, the segmental structure increases electrical utilization of the machine and decreases core losses, which leads to higher efficiency. To verify the segmental structure, finite element method (FEM) is employed to get static and dynamic characteristics of both SRMs. Finally, the prototypes of conventional and segmental SRMs are tested for characteristics comparisons.

• Proceedings of the KIPE Conference
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• 2015.07a
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• pp.505-506
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• 2015

In this paper, two types of switched reluctance motors (SRMs) with segmental rotors are presented in detail. One is 6/5 segmental rotor type; the other is 12/8 segmental rotor type. Both motors have the same stator, rotor and winding configurations. The stator is constructed with special stator poles in which the exciting and auxiliary poles are designed exclusively. The rotor is constructed from a series of discrete segments, each of which is embedded in the magnetic isolator. The windings are only wound on the exciting poles, and no windings are wound on the auxiliary poles. These structures result in short flux path and high flux-linkage utilization in the proposed motors, which may reduce the magneto motive force (MMF) requirement and increase the electrical utilization of the machine. To verify the proposed two structures, the characteristics of the proposed two types are analyzed and compared with that of conventional 12/8 SRM.

• Proceedings of the KIEE Conference
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• 1998.11a
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• pp.10-12
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• 1998

Pumping liquid metal in nuclear power plant application by conventional centrifugal pumps pose difficulties such as bearing wear out at high temperatures and leak proof sealing of the liquid metal. MHD machine is obtained by replacing solid conducting secondary of conventional motors with ionized gas or liquid metal. It is used for reactor cooling pump because of construction simplicity, perfect sealing and easy operation/maintenance MHD pump is complicated because it includes electromagnetic and hydrodynamic phenomena. The principle of MHD Pumps is described in this paper. We design small laboratory size Flat Linear Induction Pump(FLIP) for transferring sodium.

• Journal of the Korean Society of Mechanical Technology
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• v.13 no.4
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• pp.49-55
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• 2011

Recently, various efforts to make more speedy and precision machine tool to improve productivity and also various efforts to solve environmental problem are going on, so that dry cutting in manufacturing industry, which needs environmental conscious design and development of manufacturing technique, is becoming a very important assignment to solve. Because dry cutting does not use cutting fluid, we need other methods that can be used instead of cutting fluid, which does cooling, lubricating, chip washing, and anti-corrosion. Especially, because turning is a continuous work, the consideration of tool life and surface roughness due to continuous heat and poor lubrication is important. The purposes of this paper are the consideration of how well the compressed air can work instead of cutting fluid, and also the development of the method to select the optimum machining condition by the minimum numbers of experiments through the Taguchi method.

• The Transactions of the Korean Institute of Power Electronics
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• v.27 no.5
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• pp.397-401
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• 2022

The construction of the ITER tokamak machine is ongoing at a 77% process rate to achieve the first plasma in 2025. The 18 sets of power supply systems comprising 400 MVA thyristor AC/DC converters for the superconducting magnets supplied by Korea (KO) are being installed with other systems, such as PF converters (China), DC busbars (Russia), and cooling water systems (India), in two buildings (Europe). The system interfaces have been defined during the design stage, and the systems have been manufactured. However, during the on-site installation work, several installation and integration issues emerged due to the manufacturing tolerance and design mistakes. To continue the installation and testing, the engineers of each system resolved the interface issues, planned the commissioning, and integrated the test plan. This paper describes the on-site installation status and issues and the commissioning plan of KO AC/DC converters.

• Journal of Korea Foundry Society
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• v.38 no.1
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• pp.9-15
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• 2018

Electromagnetic continuous casting (EMCC) was used to fabricate Ti-6Al-4V alloys with properties suitable for medical applications. Ti-6Al-4V alloy ingots fabricated by EMCC were subjected to heat treatment, such as residual stress removing (RRS), furnace cooling after solution treatment (ST-FC) and water-cooling after solution treatment (ST-WC), in order to obtain characteristics suitable for the standard. After component analysis, the microstructure and mechanical properties (tensile strength and elongation) were evaluated by ICP, gas analysis, OM, SEM, a Rockwell hardness tester and universal testing machine. The Ti-6Al-4V alloy ingot fabricated by EMCC was fabricated without segregation, and the lamellar structure was observed in the RRS and ST-FC specimens. The ST-WC specimen showed only martensite structure. As a result of evaluating the mechanical properties based on the microstructure results, we found that the water-cooled heat treatment condition after the solution treatment was most suitable for the Ti-6Al-4V ELI standard.

• Korean Journal of Materials Research
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• v.4 no.5
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• pp.502-509
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• 1994

New damping measurement equipment was designed using the dynamic strain gage and high speed analog to digital signal 12 bit converter and compared it with existing equipment. The damping properties of general material and high damping material were also studied by this machine. The SDC (specific damping capacity) was measured with various heat treatment condition, initial vibration amplitude and internal stress. The vibration amplitude of high damping material is decreased within nearly less than 0.4 second after applying the initial forced vibration. But that of general material is still vibrating at the same time. After furnace-cooling heat treatment, SDCmax of Fe-lGwt.%Cr system was more than 40% and that of Fe-5.5wt.%Al alloy was more than 30% after air-cooling heat treatment. Upon increasing of initial vibration amplitude, it is detected the migration of SDCmax into the region of small vibraton amplitude. Damping capacity is decreased rapidly as the internal stress Increases. Damping measurement equipment in the present study was ahln to give the more accurate results of damping properties in the small vibration amplitude region.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.11a
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• pp.245-253
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• 2010

The present study shows some results of developing evaporative heat exchangers with mini-channels. Heat exchangers with three different water paths were manufactured and tested to compare performances of cooling and pressure drop. Among the three types of heat exchangers, Type 2 with full-etching was proved to be the best in the cooling performances for considered operating conditions, and thus it is recommended to adopt Type 2 for its simplicity of production and outstanding performance. However, Type 1 was shown to be better when it is operated at a high air inlet temperature condition. The developed evaporative heat exchanger will be installed in Environmental Control Systems(ECSs) for aerial vehicles, and it can be used effectively in case an ECS is not only limited in its weight and volume but also required to absorb heats without supplying water (or a coolant) for a certain period of time.

• Progress in Superconductivity and Cryogenics
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• v.14 no.4
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• pp.24-27
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• 2012

The measurement of the coefficient of thermal expansion (CTE) of polypropylene laminated paper (PPLP) as electric insulating material is important for its practical superconducting device application. The thermal strain induced to HTS tapes and its insulating material during cooling from room temperature might largely affect the critical current ($I_c$) of HTS tapes. In this study, the thermal contraction of PPLP material was measured during cooling from 300 K to 77 K using double extensometers. Initially, the CTE of a brass tape was measured and it was compared with a reference data. It was found that the measured thermal expansion data of the brass material approaches that of the reference one. Based on the results, it was then confirmed that the measurement technique could be applied to thin and flexible samples. Therefore, the same measurement procedure was applied to PPLP material using double extensometers. As a result, the linear CTE of the PPLP at 77 K has been measured to be ${\sim}15.3{\times}10^{-6}/K$. Also, it was found that the thermal contraction characteristics of PPLP was dominated by polypropylene on the cross direction (higher thermal contraction) while it was dominated by Kraft paper on the machine direction (lower thermal contraction). Overall, this measurement procedure could be adopted for the determination of CTE of flexible materials such as PPLP.