• Proceedings of the Korean Society For Composite Materials Conference
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• 2005.04a
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• pp.245-248
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• 2005

During manufacturing thick composite cylinders, large thermal residual stresses are developed and induce catastrophic interlaminar failures. Since the residual stresses are dependent on many process parameters, such as temperature distribution during cure, cure shrinkage, winding tension, and migration of fibers, calculation of the residual stresses is very difficult. Therefore a radial-cut method have been used to measure the residual stresses in the composite cylinders. But the conventional radial-cut method needs to know numerous material properties which are not only troublesome to obtain but also vary with change of fiber arrangement during consolidation. In this paper, a new radial-cut method with cut-cylinder-bending test was proposed and the measured residual stresses were compared with calculated thermal residual stresses. It was found that the new radial-cut method which does not need to know any of material properties gave better estimation of residual stresses regardless of radial variation of material properties. Additionally, interlaminar tensile strength could be obtained by the cut-cylinder-bending test.

• Progress in Superconductivity and Cryogenics
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• v.13 no.1
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• pp.12-16
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• 2011

In this paper, the prototype of the HTS motor with an on-board cryocooler, is fabricated and tested. The overall system is composed of the stator with conventional copper winding, the rotor with superconductor, and the rotating cryocooler designed from the on-board concept. The rotor is fabricated as the race-track coil with 2G, YBCO tape and contacts with the on-board cryocooler while being rotated together. An inline-type pulse tube refrigerator is used as the on-board cryocooler. The cryocooler is fabricated from optimal process to satisfy the structure and thermal stability of the on-board system. Each component is integrated according to carefully defined sequence. Specially, a combining method of torque tubes is an important part for sustaining stability of the rotor and the cryocooler. In the rotating test, the HTS motor is successfully operated with 240 rpm of rotating speed when 75 A current is supplied to the superconducting rotor. In this paper, potential problems of the HTS motor system using the on-board cryocooler are proposed and solved, and realistic possibility of this concept is also confirmed.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.520-522
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• 2011

In this paper, the bearing strengths and fracture behaviors of the pin-jointed carbon fiber/epoxy composites were investigated through pin loading test. The composites were fabricated by a filament winding process, and two types of laminated patterns were considered. According to the results, type 1 pattern revealed a net-tension failure mode, whereas type 2 pattern exhibited a bearing failure mode. Also, acoustic emission energy of the type 2 pattern was higher than that of the type 1 pattern. Therefore, the type 2 pattern was found to be structurally safer than the type 1 pattern.

• The Transactions of the Korean Institute of Power Electronics
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• v.12 no.6
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• pp.472-482
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• 2007

The LLC series resonant converter with a LLT (Inductor-Inductor-Transformer) transformer design process and experimentation results for PDP TV power supply is presented. LLT transformer used to combine the inductor and transformer into one unit has the increased leakage inductance in the primary and secondary due to the winding method and the use of the gaped core. The increased leakage inductance in the primary and secondary of LLT transformer can be impacted on the DC voltage gain characteristics of LLC series resonant converter, In this paper, DC gain characteristics and the experimental results of the LLC series resonant converter with a LLT transformer are verified on the Math-CAD simulation based on the theoretical analysis and the 600W experimental prototype.

• The Research Journal of the Costume Culture
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• v.9 no.3
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• pp.398-411
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• 2001

Funeral rites relate to the last ceremonies involving the process of human beings moving from this world to the other world, becoming part of a life which remarkably reflects the world after death. They can be said to be the best culture created by the conception of death. The ceremonies of mourning, or ubiquitius folk phenomena of all the ages from the ancient times to modern times, represent the mass belief of each nation in spiritual worlds as well as the feelings of individuals facing death. In so far as their methods are concerned, the ceremonies vary in accordance with ages, nations, regions and culture. The practices of today\`s funeral rites conducted in the West have been formed and changed throughout its long history. Now that the ceremonies are a combination of complicated cultures, they serve as an important tool for inquiring into the spiritual life of the people of an age in question and the pictures of the society concerned. Therefore this paper is designed to look into the culture of shrouds showing respect for the dead in the West. With the view of examining death, and grave clothes for them, but also with the spiritual culture of human beings in relation to death represented in their pictures. I resort to literature and materials related to the shrouds of the dead which appeared in a period from the Medieval Age to the 19th century.

• Progress in Superconductivity and Cryogenics
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• v.7 no.4
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• pp.24-27
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• 2005

Development of a 600 kJ class Superconducting Magnetic Energy Storage (SMES) system is being in progress by Korea Electrotechnology Research Institute(KERI). High temperature superconducting (HTS) wires are going to be used for the windings for the SMES system is presented in this paper. We considered BSCCO-2223 wire for the HTS windings and the operating temperature of the winding was decided to be 20 K which will be accomplished by conduction cooling method using cyro-coolers. Auto-Tuning Niching Genetic Algorithm was adopted for an optimization method of the HTS magnets in the SMES system. The objective function of the optimal process was minimizing total amount of the HTS wire. As a result, we obtained output parameters for optimization design of 600 kJ class SMES under several constrained conditions. These HTS windings are going to be applied to the SMES system whose purpose is stabilization of the power grid.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07b
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• pp.1248-1253
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• 2004

This work describes the effect of electrode binder on the characteristics of electric double layer capacitor Among carboxymethylcellulose (CMC), Polyvinylpyrrolidone (PVP), Polyvinyl Alcohol (PVA), and Polyvinylidene Fluoride (PVDF), the unit cell using CMC showed good rate capability between $2.5mA/cm^2{\sim}100mA/cm^2$ current density. However, CMC as a binder is incongruent, because the electrode bound with CMC is rigid and easy to crack during a press and winding process for fabrication of capacitor. The unit cell capacitor using the electrode bound with binary binder composed of CMC and Polytetrafluoroethylene (PTFE), especially in composition CMC : PTFE : 60 : 40 wt.%, has exhibited the better mechanical properties than those of the unit cell with CMC. On the other hand, it was also noted that the mechanical properties of CMC+PTFE electrode, coated on underlayer composed of CMC and carbon black, were much improved the binding force.

• Journal of international Conference on Electrical Machines and Systems
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• v.3 no.3
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• pp.256-263
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• 2014

Torque ripple is a very essential index for evaluating the effectiveness of a switched reluctance motor (SRM). Many common design strategies for reducing torque ripples of a SRM are changing the excitation trigger angle of stator windings, delaying the cut-off time of winding excitation, adjusting the ratio of arc angle between stator and rotor, and changing the geometric shape of rotor. However, the output torque or the efficiency of the SRM may drop as the above design strategies are solely adopted. In this paper, a hybrid design model which is obtained by the Taguchi Method for optimally designing a SRM with lower torque ripple and higher efficiency is presented. A 12S/8P motor is taken as a study case, and the 3D finite element method (FEM) is applied to analyze the characteristics of the motor and optimize the design process. The results have shown that the proposed method can achieve the design goal of obtaining a high-performance SRM for light electric vehicle applications.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.10
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• pp.1079-1084
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• 2004

This work describes the effect of electrode binder on the characteristics of electric double layer capacitor. Among carboxymethylcellulose (CMC), Polyvinylpyrrolidone (PVP), Polyvinyl Alcohol (PVA), and Polyvinylidene Fluoride (PVDF), the unit cell using CMC showed good rate capability at current densities between 2.5 mA/$\textrm{cm}^2$～100 mA/$\textrm{cm}^2$. However, CMC as a binder is incongruent, because the electrode bound with CMC is rigid and easy to crack during a press and winding process for fabrication of capacitor. The unit cell capacitor using the electrode bound with binary binder composed of CMC and Polytetrafluoroethylene (PTFE), especially in composition CMC : PTFE =60 : 40 wt.%, has exhibited the better mechanical properties than those of the unit cell with CMC. On the other hand, the mechanical properties of CMC+PTFE electrode, coated on underlayer composed of CMC and carbon black, were much improved.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.5
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• pp.165-170
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• 2001

In the continuos process systems, traction between a moving web and rollers is one of key mechanisms for the study of major issues including the distributed control of tension, guiding, wrinkling, winding, and scratching. Energy is transferred from the driven rollers to the web and from the web to the idle rollers through traction. The characteristics of friction play major role in the determination of the traction force between the moving web and the rollers. In this paper the characteristics of friction between the moving web and the rollers are studied. A procedure to determine the friction coefficient between the moving web and rollers is developed. An experimental setup to validate the procedure is devised. Experimental results showed that the value of traction coefficient decreases as the operating web speed increases and increases as the operation web tension increase.