• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.9
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• pp.1431-1436
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• 2017

The high-speed railway of catenary system, supplies a stable electric power supply to the train by satisfying the special conditions between pantograph and trolley wire, which operates more than 250km/h mutually sliding and feeding electric lines. According to Korean Railway Standard KRS PW 0026-13 (R), the standard for the grip strength of the dropper clamp in conventional line is established, but the high-speed railway line is not yet. When the grip strength of the dropper clamp is detached from the catenary line of the high-speed railway line, various problems may occur, such as damage to the pantograph due to the collision and arcing. In this paper, it is expected to be used as a basic data for establishing the durability criteria of the high-speed railway dropper clamp by verifying the dropper clamp on the Gyeong-bu and Honam high-speed line.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.8
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• pp.1163-1168
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• 2013

The maximum allowable value of loop impedance($Z_s$) to secure the operation of overcurrent protective devices and the safety for indirect contact is a very important in TN-C-S system. The loop impedance is divided into inner loop impedance which consumer can adjust and external loop impedance($Z_e$) which only electric operator can adjust. Thus, an external loop impedance which limits to less than a certain value is a very important factor for human body protection against electric shock in TN-C-S system. The concept of loop impedance($Z_s$) is recently introduced to the domestic, the study about external loop impedance is yet insufficient. However, the study about the reference impedance as specified by the IEC 60725 standard to improve the quality and reliability of the power supply is being made. In this paper, reference value of external loop impedance($Z_e$) to meet domestic environment will be proposed by the nationwide measurement and statistical analysis.

• Fire Science and Engineering
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• v.24 no.5
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• pp.136-141
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• 2010

The purpose of this study is to examine the structure and heat generation mechanism of low voltage switches used to turn on or off the power supply to an indoor lighting system and investigate how the fixtures and movable contacts of the switches are damaged depending on the types of energy sources in order to secure the judgment base for expected PL disputes. Based on the Korean Standard (KS) testing method for incombustibility, this study applied a general flame to the switch. In addition, current was supplied to the switch using the PCITS (Primary Current Injection Test System). The ambient temperature and humidity were maintained at $22{\pm}2^{\circ}C$ and 40~60% respectively while performing the test. It is thought that the switch generated heat due to a defective connection of the wire and clip, insulation deterioration and defective contact of the movable contact, etc. The surface of the switch damaged by the general flame was uniformly carbonized. When the flame source was removed, the fire on the switch was extinguished naturally. From the result obtained by disassembling the switch carbonized by the general flame, it could be seen that fixtures and movable contacts remained in comparatively good shape but the enclosure, clip support, movable contact, indicating lamp, etc. showed carbonization and discoloration. In the case of the switch damaged by overcurrent, the clip connecting the wires, clip support, etc. showed almost no trace of damage, but the fixtures, movable contact, indicating lamp, etc. were severely carbonized. That is, the sections with high contact resistance were intensively damaged and showed a damage pattern indicating that carbonization progressed from the inside to the outside. Therefore, it is possible to judge the initial energy source by analyzing the characteristics of the carbonization pattern and the metal fixtures of damaged switches.

• Journal of the Korean Society for Precision Engineering
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• v.25 no.6
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• pp.71-79
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• 2008

In the manufacture of flat panel display devices, there is a strong demand for contactless glass panel handling devices that can manipulate a glass panel without contaminating or damaging it. To fulfill this requirement, an electrostatic suspension device far glass panels where the glass panel is supported by electrostatic forces without any mechanical contact is proposed. To implement the system with low cost and compactness, switched-voltage control scheme that is based on the relay feedback control is utilized. Relay feedback control method deploys only a single high-voltage power supply that can deliver a DC voltage of positive and/or negative polarity and thus high voltage amplifiers that are costly and bulky are not needed any more. It is shown that despite the inherent limit cycle property of the relay feedback based control, an excellent performance in vibration suppression is attained due to the presence of a relatively large squeeze film damping originating from the electrodes and levitated object. Using this scheme, a $100{\times}100mm^2$ glass panel was levitated stably with airgap variation decreasing down to $1\;{\mu}m$ at an airgap of $100\;{\mu}m$.

• Journal of Aerospace System Engineering
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• v.11 no.5
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• pp.28-35
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• 2017

Magnetic Suspension and Balance System (MSBS) demonstrates the capacity to levitate an experimental model absent any mechanical contact using magnetic forces and moments. It allows precise control of position and attitude of the model, and measures external forces and moments acting on the model. For the purpose of acquisition of reliable experimental results under stable and safe conditions, the performance and robustness of the position and attitude control system of MSBS needs to be improved. To this end, Iterative Feedback Tuning (IFT) and L1 adaptive output feedback algorithm were employed to automatically increase command following performance and to ensure robust operation of MSBS with failure of electric power supply. The applicability was validated using computational simulation.

• Journal of Power System Engineering
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• v.9 no.2
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• pp.81-87
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• 2005

This study is numerical analysis on the increasing temperature characteristics of vaporizer fin for liquefied natural gas with super low temperature. Existing LNG vaporizers use the direct contact heat transfer mode where the extreme super low temperature LNG of $-162^{\circ}C$ flows inside of the tubes and about $20^{\circ}C$air flows on outside of the fin. Recently, the vaporizers with great enhanced performance compared to conventional type have been developed to fulfill these requirements. The vaporizing characteristic of LNG vaporizer with air as heat source has a fixed iced. These characteristic cause a low efficiency in vaporizer, total plant cost and installing space can be increased. The vaporizing characteristics of LNG via heat exchanger with air are analytically studied for an air heating type vaporizer. This study is intended to supply the design data for the domestic fabrication of the thickness and angle vaporizer fin. Governing conservation equations for mass, momentum and energy are solved by STAR-CD based on an finite volume method and SIMPLE algorithm. Calculation parameter is fin thickness, setup angle and LNG temperature. If the vaporization performance of the early stage and late stage of operating is considered, the case of ${\phi}=90^{\circ}$ was very suitable. In this paper was estimated that the heat transfer was most promoted in case of THF=2mm.

• International Journal of Computer Science & Network Security
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• v.22 no.2
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• pp.341-347
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• 2022

This research is designed to help and offer hold up to complete the requirements of aged and disable in a home. The control approach and the tone approach are used to manage the house appliances. The major organize system implementation in technology of wireless to offer distant contact from a phone Internet Protocol connectivity for access and calculating strategy and appliance remotely. The planned system no need a committed server PC with value of parallel systems and offers a new communication-protocol to observe and control a house environment with more than just the switch functionality. To express the possibility and efficiency of this system, devices like as lights switches, power plugs, and motion-sensors have been included with the planned home control system and supply more security manage on the control with low electrical energy activate method. The rank of switches is corresponding in all this control system whereby all user interfaces indicate the real time existing status. This system planned to manage electrical-appliances and devices in house with reasonably low cost of design, user friendly interface, easily install and provide high security. Research community generally specified that the network "Reconnaissance Attacks" in IPv6 are usually impossible due to they will take huge challenge to carry out address scanning of 264 hosts in an IPv6 subnet."It being deployed of IPv6 shows that it definitely enhances security and undermines the probability". This research of the IPv6 addressing-strategies at present utilizes and planned a new strategy and move toward to "mitigate reconnaissance attacks".

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.3
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• pp.2301-2307
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• 2015

The aim of this study was to evaluate the feasibility of application of the high voltage impulse (HVI) technique to the control of scale formation by calcium carbonate, which is pointed out as an important issue in industrial water treatment. The HVI system consisted of the power supply, high voltage generator, capacitors, switch and impulse generator was designed and made in laboratory scale, which can make 17kV impulse. HVI was introduced to the reactor that was filled with synthetic water containing $Ca^{2+}$ion. The concentration of calcium ion decreased only 3.0% after 5 minutes of contact time. However, it decreased up to 13.7% after 60 minutes of HVI contact time. Temperature and pH increased but conductivity decreased due to precipitation of the calcium carbonate. Although the decrease in concentration of calcium ion was not sufficient, it was verified that the HVI technique could be applicable for the softening and desalting processes.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.3
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• pp.1302-1307
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• 2011

The Spiral coil is made considering primary, secondary side coil inductance, turn number, size, thickness, and shielding area with the litz wire-type in case of manufacturing a coil, and at this time, the semi-automation winding machine is used. When deciding on primary and secondary side coil specification and manufacturing a coil, the spiral coil of a specification varied in the various litz wire of a specification is required, and at this time, a difficulty is generated by the manufacture cost, period which during, and failure the manufacture is generated in the coil sample making. A difficulty is in the desired coil quality control of a specification. Since improving the rectifier of the secondary side in order to improve this kind of problem, the range of the coil design and the during the manufacture, various coil manufacture specifications can be comprehensively made.

• Journal of the Semiconductor & Display Technology
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• v.4 no.1 s.10
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• pp.9-16
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• 2005

In this paper, with loosely coupled transformer Relies-parallel resonant type DC/DC converter is analyzed and adopted to the power source of a TFLM(Transverse Flux Linear Motor). To get more efficient operating mode of the series-parallel resonant type DC/DC converter, theoretical analysis using normalized parameters are accepted. The analysis includes a specially made ferrite transformer with two separately wound half cores in order to evaluate analytically and experimentally the changes in magnetizing the leakage fluxes and inductances caused by the distance between the halves. The proposed converter must be operated in switching Pattern III among the three switching patterns for the Zero Voltage Switching operation. According to Pulse Frequency Modulation(PFM) control method, the output voltage of the proposed circuit can be controlled. The results of the theoretical development are compared with practical measurements from a prototype system.