• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.11
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• pp.1015-1025
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• 2010

In this present study, we experimentally investigated the effects of electric fields on the characteristics of flames spreading over electric-wires with AC fields. The dependence of the rate at which a flame spreads over polyethylene-insulated wires on the frequency and amplitude of the applied AC electric field was examined. The spreading of the flame can be categorized into linear spreading and non-linearly accelerated spreading of flame. This categorization is based on the axial distribution of the field strength of the applied electric field. The rate at which the flame spreads is highly dependent on the inclined direction of the wire fire. It could be possible to explain the spreading of the flame on the basis of thermal balance.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.6 no.4
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• pp.130-137
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• 1997

The demand for wire-cut EDM is increasing rapidly in the die and tool making industry. In this study machining characteristics such as machining rate, surface roughness, hand drum form and hardness of machined material are investigated experimentally under the conditions varing pulse on time, pulse off time, peak voltage, wire tension after fixing other conditions in SKD 11 and brass and brass workpiece. It was found that various operating conditions had significant influences on machining characteristics. But the hardness of workpiece was uneffected by operating conditions. Also it was obtained experimentally that brass workpeice had better machinability than SKD 11 one.dition according to the current(Ip) in an electric spark machine : 1) Electrode is utilized Cu and Graphite. 2) Work piece is used the material of carbon steel. The condition of experiment is : 1) Current is varied 0.7(A) to 50(A) and the time of electric discharging to work piece in each time is 30(min) to 60(min). 2) After the upper side of work piece was measured in radius(5$\mu$m) of stylus analyzed the surface roughness to ade the table and graph of Rmax by yielding data. 3) Electro wear ratio is : \circled1Cooper was measured ex-machining and post-machining by the electronic balance. \circled2The ex-machining of graphite measured by it, the post-machining was found the data from volume $\times$specific gravity and analyzed to made its table and graph on ground the data. 4) In order to keep the accuracy of voltage affected to the work piece was equipped with the A.V. R and the memory scope was sticked to the electric spark machine. 5) In order to preserve the precision of current, to get rid of the noise occured by internal resistance of electric spark machine and to force injecting for the discharge fluid , it made the fixed table for a work piece to minimize the work error by means of one's failure during the electric discharging.

• Journal of the Korean Society of Propulsion Engineers
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• v.14 no.6
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• pp.89-102
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• 2010

In this paper, a study on the future-oriented actuator introduces the future technology and future direction in aerospace and several industry fields. In particular, the mechanical linkage or hydraulic and pneumatic actuators which have the higher output-to-weight ratio have been used a lot in the past as the aircraft's flight control device. Most recently, Fly-By-Wire system has been used in aircraft and the flight control system has been changed in more electric and all electric systems. Electrohydraulic actuators and electric actuators have been developed continually, because they have better efficiency, safety and lower cost for the flight control system of aircraft. Also, to improve the weight condition, accuracy and response of actuator, new field actuators using new materials have been developed. In this paper we clearly proposed the actuator design and detailed technology development trend for next generation actuation system in aerospace and new field.

• Journal of Korean Society for Atmospheric Environment
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• v.15 no.1
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• pp.33-39
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• 1999

This study has been performed to develop an efficient electrocharged scrubber. To improve collection efficiency of the scrubber, electric-charger was installed at the forefront of the packed crossflow scrubbers, and an experiment of changing discharge electrode shape and fluctuating electric field strength was undertaken. After using a light-oil boiler for generation of particles in the about 80% weight of submicron size particles was exhausted. Collection characteristics of the electrocharged scrubber were similar to those of two-stage electrostatic precipitator. In this study the collection efficiency of submicron size particles has been much improved, compared with the previous ones. In an experiment of changing discharge electrode and electric field strength, a needle-spike shape wire electrode showed a higher collection efficiency than round shape wire. The collection efficiency becomes increased with an increase of electric field strength.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.59 no.2
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• pp.206-211
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• 2010

Since high-speed train is a dynamic load in which electric power is externally supplied, contact loss between the catenary and pantograph occurs. This phenomena including vibrations generates frequently irregular arcs, which, in turn causes EMI. Thus it is very important to develop the approach to reduce arc phenomenon by contact loss, as speed of electric railway vehicle increases. In case of an electric railway vehicle using electrical power, compared with diesel rolling stock, Power Line Disturbance(PLD) such as harmonics, transient voltage and current, Electromagnetic Interference(EMI), and dummy signal injection etc usually occur. In this study, the dynamic characteristics of a contact wire and a pantograph suppling electrical power to high-speed train are investigated with an electrical response point. To implement power line disturbance induced by contact loss phenomenon for high speed train operation, a hardware simulator which considers contact loss between contact wire and pantograph as well as contact wire deviation is developed. It is confirmed by the experiments that contact loss effect is largely dependent on voltage conditions when the contact loss occurs. Also, a passive filter is designed to reduce power disturbance and the designed system is verified by experiment.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.25 no.7
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• pp.496-502
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• 2015

In this study, seismic performance tests for 500 kV EBA are conducted through the IEEE Std. 693. It is hard to conduct both the static tests and dynamic tests for 500 kV EBA as IEEE Std. 693 because the size of specimen, 9 m in height, is too large to be examined. To do so, it can cause the unnecessary time and cost, and also the damage on the specimen. However, in this study, both static tests and dynamic tests are conducted in the same test field as IEEE Std. 693 to achieve more accurate and reliable test results. From the test results Taihan Electric Wire Co. can win contract for 500 kV extra-high voltage project in the U.S.A., therefore it can be evaluated that the tests are conducted successfully and the capability to estimate large electric power facilities are achieved as IEEE Std. 693.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.32 no.6
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• pp.507-511
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• 2019

The purpose of an electric railway system contact wire is to supply electric energy to trains through a contacted pantograph. This energy is then converted into mechanical energy. Recent developments in overhead contact lines include the increase in the tension force up to 34 kN according to train speeds that reach up to 400 km/h with a verified safety. Rigid conductor catenary (R-Bar) for high speeds of up to 250 km/h have been developed in tunnels to save on construction costs. This is significant because minor defects in R-bars in aspects, such as height and stagger affect installation conditions. In this study, we propose the use of a detector that measures the static characteristics to reduce the R-bar installation errors. This detector has been developed to measure the height and stagger of the contact wire using video images.

• Transactions of Materials Processing
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• v.27 no.4
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• pp.244-249
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• 2018

Rhodium is a representative platinum group material. Rhodium is used in several industrial fields including jewelry, chemical reaction catalyst, electric component etc. In recently, ultra-fine rhodium wire has been applied to the pins of probe card used to test a semiconductor. In this study, in order to produce a fine rhodium wire with the diameter of $50{\mu}m$, a fine rhodium wire drawing process was designed. After design of the fine wire drawing process by using a uniform reduction ratio theory, finite element analysis was performed. Finally, fine wire drawing experiment was performed to verify the effectiveness of the designed process.

• Progress in Superconductivity and Cryogenics
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• v.9 no.1
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• pp.57-60
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• 2007

Superconducting electric power devices need to stack HTS wires to increase the current carrying capacity. Uniform multi-stacked wires(UMS) which were made of the same HTS wires have been used. This paper shows the magnetization loss of hybrid multi-stacked(HMS) wire made of BSCCO wires and YBCO wires. Five HMS wires, YB(YBCO-BSCCO), YYBB. YBYB, YBBY and BYYB, were made and tested. Magnetization losses of each UMS wire were compared with corresponding HMS wire. Test results show that magnetization losses per unit length of HMS wire are between the corresponding UMS BSCCO wire and HMS YBCO wire below critical magnetic field. Above the critical magnetic field, magnetization losses of HMS wires are larger than that of corresponding both VMS wires.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2012.05a
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• pp.935-936
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• 2012