• Journal of the Korean Society of Safety
• /
• v.28 no.3
• /
• pp.56-62
• /
• 2013

The occurrence of the ventricular fibrillation is directly dependent on the magnitude and duration of the current. The current which flows through the human body is proportional to the touch voltage applied across the body and is in inverse proportion to the impedances in the circuit. The circuit impedances consist of human body impedance, line impedance, equipment impedance, earth terminal impedance and impedance of shoes which a person put on. The impedance of shoes greatly affect the severity of the electric accidents. The human body impedances relevant to the contact areas, contact conditions, current paths and touch voltages are already determined in the IEC 60479-1. However, the impedance of shoes is ignored or substituted by a simple value because of the absence of the sufficient data. For example, the impedance of shoes plus ground contact resistance is postulated to be $1,000{\Omega}$ in the IEC 61200-612. In IEEE 80, the shoe resistance plus ground contact resistance is assumed to be bare foot with ${\rho}/4b{\Omega}$. In this paper, we measured and analyzed the impedance of shoes with respect to conditions such as applied weight, environment variables and voltages. The results showed that the impedance of shoes is dependent on environment variables regardless of the types of shoes. Most of shoes showed the correlation with the applied force, whereas a few shoes showed characteristics related to the applied voltage. In terms of severity of electric shock, one thirds of test samples indicated to be dangerous in saltwater conditions.

• Proceedings of the KIEE Conference
• /
• 2002.07b
• /
• pp.1015-1017
• /
• 2002

This is the study on static excitation system of synchronous generator of large capacity in new model, which was developed by KEPRI using triple redundant digital method, associate three bridges of thyristor phase controlled rectifier. This paper will discuss the design conception and the application results of system which includes the power control devices(thyristors, GTO) and power excitation potential transformer. The multi-paralleling thyristor bridge converters of N+1 method have firing circuit. The initial product manufactured by proposed design in the study is in commercial operation, completing installation and commissioning in 400MW Thermal Power Plant. The performance test is done in practical technique.

• Tribology and Lubricants
• /
• v.18 no.4
• /
• pp.299-304
• /
• 2002

This paper reports the studies on the wear-corrosion behavior of ductile cast iron in the acidic environment. In atmosphere and variety of pH solution, specific wear rate and wear-corrosion characteristics of GCD 60 with various sliding speed and distance were investigated. And electrochemical polarization test of GCD 60 was examined in the environment of various pH values. The main results are as following : As the contact pressure increases, the critical velocity of specific wear rate becomes transient at low sliding speed. As pH value becomes low, wear-corrosion loss increases in the aqueous solution. As the corrosion environment is acidified, corrosion potential of GCD 60 becomes noble and corrosion current density increases.

• Proceedings of the KSR Conference
• /
• 2011.05a
• /
• pp.948-953
• /
• 2011

In AC railway feeding system, three phase received from the network is changed to two phase power sources with different phases. The main circuit breaker installed train is automatically open by track signal when the train passes the neutral section. In order to continuously supply power source to train, the changeover system was used in Japan. Therefore, the train is able to operate under powering condition when it was passing through the neutral section. We investigated the control method to reduce the inrush current flowing main transformer in train. To examine the inrush current and operate the static semiconductor switch such as thyristor, we manufactured the small scale the changeover system and carried out performance tests.

• Journal of the Korean Society of Manufacturing Technology Engineers
• /
• v.9 no.4
• /
• pp.137-146
• /
• 2000

The hydraulic energy regnerative brake systems is introduced in this work. An accumulator stores kinetic energy during braking action, and the stored energy is used in a following acceleration action. The dynamic model of the brake system is derived for computer simulation study, and the Runge-Kutta numerical integration method is applied to the simulation work. Since the model contains several unknown parameters, these were determined by data which had been proceeded. Through a series of computer simulation , dynamic performance of the energy regenerative brake system is compared with that of a conventional system in which a conventional brake circuit is used. A series of test is carried out in the laboratory. The dynamic characteristics of the hydraulic motor system, such as the surge pressure and response time, are investigated in both brake action and acceleration action.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
• /
• 2001.10a
• /
• pp.304-310
• /
• 2001

Flow pulsation often causes vibration and noise in piping systems and therefore has been a troublesome concern for fluid system engineers. According to frequency increase in this paper under the influence wave form of velocity in springly flow and viscosity are drop coefficient of viscosity become increase so that impedance and resistance. The transient variations of flow rate are measured by a modified impedance tube method which is realized by virtue of the present analytical technique. At pipe line in order to eliminate vibration, confirm happened intermittently impedance characteristics. We make a test and frequency analysis and have to minimize obstructive component at hydraulic circuit.

• Journal of Electrical Engineering and Technology
• /
• v.10 no.5
• /
• pp.2001-2008
• /
• 2015

This paper proposes the concept of FlexPCB(flexible Printed Circuit Board) conductive structure for electrodynamic bearings. It has three main advantages: easy “printing” of considerably thin conductive wires, resulting in potential reduction in stray eddy currents; realization of specific conductive configurations with high precision to optimize the eddy current flowing; simplicity in being wound to cylinders or hollow cylinders of different diameters. To verify this new concept, the FlexPCB conductive structure was manufactured, an axial electrodynamic bearing test rig was built and the conductive structure's induced voltage was measured along the axial displacements from 0mm to 56mm at three rotating speeds. The finite element method was used to calcuatlate the flux density of electrodynamic bearing and induced voltage of the FlexPCB conductive structure. The experimental results are compared with the results from the FEM calculation. It is concluded that the measured and calculated induced voltages have consistency in the middle part of the bearing.

• Journal of Electrical Engineering and information Science
• /
• v.3 no.1
• /
• pp.8-13
• /
• 1998

Often ESOP(Exclusive Sum of Products) expressions provide more compact representations of logic functions and implemented circuits are known to be highly testable. Motivated by the merits of using XOR(Exclusive-OR) gates in circuit design, ESOP(Exclusive Sum of Products) expressions are considered s the input to the logic synthesis for random pattern testability. The problem of interest in this paper is whether ESOP expressions provide better random testability than corresponding SOP expressions of the given function. Since XOR gates are used to collect product terms of ESOP expression, fault propagation is not affected by any other product terms in the ESOP expression. Therefore the test set for a fault in ESOP expressions becomes larger than that of SOP expressions, thereby providing better random testability. Experimental results show that in many cases, ESOP expressions require much less random patterns compared to SOP expressions.

• Journal of the Korean Institute of Telematics and Electronics D
• /
• v.36D no.4
• /
• pp.8-17
• /
• 1999

In this paper, a proposal for improving the performance of IF in-phase combiner is presented in view of simple hardware design and good performance for space diversity application. By adding the stable normalization circuit to the phase detector, better performances are obtained even for a severe notch depth of 30 dB. To check the validity of this proposal, various results based upon numerical simulation and laboratory test are presented here in conjunction with 64-QAM digital radio relay system.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
• /
• 2004.10a
• /
• pp.468-473
• /
• 2004

This paper deal with basic concept of Hardware In the Loop System(HILS) for hydraulic excavator. Hydraulic excavator has many nonlinearities because of P-Q diagram, dead zone and saturation of valve, single acting cylinder, heavy manipulator. So, actual test is needed when new component or control algorithm is developed but many restrictions exist. Hydraulic circuit of excavator is too complex to model mathematically but dynamic equation of manipulator has made good progress in previous studies. Basic concept of HILS and AMESim model of hydraulic components is contained in this paper.