• The Korean Journal of Physiology
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• v.23 no.1
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• pp.35-42
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• 1989

The present study was performed to observe the effects of cations on resting membrane potential and pump activity in the unfertilized eggs of ICR strain mice. After an induction of superovulation, the fresh eggs with zona pellucida were collected and the membrane potentials were recorded. Recordings of membrane potential in this study was obtained from the physiological conditions ($37^{\circ}C$ and 4mM Ca in standard solution), differently from the another reports with unphysiological conditions (room temprature and high Ca in standard solution) for a stable and long-lasting observations. Presented data was obtained within 6 hours after collection from the oviduct. The results observed are as follows, 1) Resting potential of the unfertilized eggs was $-25.8{\pm}3.8mV$ $(Mean{\pm}Se,\;n=31)$. 2) As the K ion concentration was increased, resting membrane potential was depolarized but showed hyperpolarization with $K^{+}$ below 25mM. 3) Alteration of the resting membrane potential for the changes of $Na^{+}$ concentration were hardly observed, while resting potential was hyperpolarized as $Ca^{2+}$ concentration was increased. 4) Pump activity as transient or prolonged hyperpolarization was $-2.29{\pm}0.75mV$ $(Mean{\pm}Se,\;n=16)$, the hyperpolarization was increased in both amplitude and duration under the 10mM $Ca^{2+}$ solution. 5) Hyperpolarization due to pump activity was decreased or disappeared by $5{\times}10^{-5}\;M$ ouabain treatment and could not be observed under the both Na-free and Ca-free solutions. 6) Above results are likely to suggest that the resting potential of the mouse unfertilized eggs is affected to mainly by Ca-dependent K conductance and Na-Ca exchange mechanism and that there is pump activity coupling between $K{+}$, $Na^{+}$ and $Ca^{2+}$.

• Journal of Power System Engineering
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• v.9 no.2
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• pp.45-49
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• 2005

Liquefied natural gas takes up six hundredths of the volume of natural gas, which makes storage and transportation much easier. To send out natural gas via a pipeline network across the nation, high-pressure LNG pumps supply highly compressed LNG to high-pressure vaporization facilities. The Number of high-pressure LNG pumps determined the send-out amount in LNG receiving terminal. So it is main equipment at LNG production process and should be maintained on best conditions. In this paper, to find out the cause of high beat vibration at cryogenic pumps, vibration and motor current signal analysis have been performed. High vibration of cryogenic pumps could be reduced due to the modification of motor rotor.

• Proceedings of the KIEE Conference
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• 1993.11a
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• pp.198-200
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• 1993

This paper represents the experimental results of electrohrdrodynamic(EHD) micropump driven by traveling- wave voltage. We fabricated 60 electrodes array with $100{\mu}m$ width and $100{\mu}m$ interval on the pyrex glass. On that glass we fabricated the micro channel which had the cross section of 3mm by 0.5mm. This pump was driven by 6 phase square traveling-wave voltage. We used the corn oil for experiments and increased the temperature of fluid by resistive heater. An optical microscope with CCD camera and monitor was used for observation. The fluid velocity was large for the large driving voltage and the high temperature. This EHD pump had the fluid velocity in specific frequency (near 1Hz) which had relation to the charge relaxation time in that oil.

• Proceedings of the KIPE Conference
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• 2005.07a
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• pp.421-423
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• 2005

A bootstrap circuit for floating power supply has the advantage of being simple and inexpensive. However, the duty cycle and on-time are limited by the requirement to refresh the charge in the bootstrap capacitor. Hence, this paper deals with a design of charge pump circuit for a floating gate power supply of an IPM. The operation of the proposed circuit applied by three-phase inverter system for driving induction motor are verified through the experiments.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.258-259
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• 2011

This paper shows the load characteristics of IH (Induction Heating) Cookers which are those of essential appliances for electrifying residential buildings in smart places. Load experiments are carried out in the same manner as like previous two studies. The results will be used to develop new load models for smart places including heat pump loads for analyzing changed power system environments by the smart grid.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.11a
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• pp.400-405
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• 2005

The diagnosis of mechanical load and of power transmission system failures is usually carried out through mechanical signals such as vibration signals, acoustic emissions, motor speed envelope. If the mechanical load comes from an electrical machine the mechanical failures could be detected previously. Mechanical rotor imbalances and rotor eccentricities are reflected in electric, electromagnetic and mechanical quantities. Therefore, many surveillance schemes apply to the Fourier spectrum of a line current in order to monitor the motor condition. Due to the interaction of the currents and voltages, both these current harmonics are also reflected by a single harmonic component in the frequency spectrum of the electric power. Motor Current Signature Analysis is the usuful technique to assess machine electrical condition.

• Proceedings of the Korean Nuclear Society Conference
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• 2004.10a
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• pp.299-300
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• 2004

• Asian Pacific Journal of Cancer Prevention
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• v.13 no.6
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• pp.3005-3006
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• 2012

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.23 no.1
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• pp.65-72
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• 2013

This case study presents a practical method to reduce resonant vibration of large vertical pumps. The pumps are driven at 400 rpm rated speed by induction motor. The vibration was not significantly large when operated at this rated speed. Large vibration was occurred when the pump was operated below the rated speed for flow control. Due to the large vibration resonance, variable speed operation of the pump was not possible for several months at worst cases. To find an efficient vibration control method, the flexural responses of pumps for both normal and transient operations were measured. The measured modal characteristics were compared with those of finite element analysis. When the pump was operated at a specific rpm, the natural mode whose resonance frequency is twice the rotating angular speed induced the large vibration. The retrofit utilizing stiffeners to reduce this resonant vibration were performed. Effects of designed stiffeners on reducing vibration were validated through tests after actual installation.

• Proceedings of the KIEE Conference
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• 2006.10d
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• pp.212-214
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• 2006

Air Management System is composed by Pump, Fan, Compressor and Blower In general their performances depend on the capability of the motor, power converter device and controller. Especially, it should be noticed upon designing Air Management System using for Fuel Cell System, that Pump, Fan, Compressor and Blower satisfy the condition of the high performance, high efficiency, high density and reasonable price considering the safety and Economic Efficiency. In order for this, it should be studied that which kind of Motor is the most suited for Air Management System for Fuel Cell, such as Induction Motor, Brushless DC Motor, and Switched Reluctance Motor which is widely using in industry. This paper presents the designing and manufacturing of Outer Rotor Type BLDC Motor and Driver for Air Blower of Air Management System. Experimental results from a laboratory prototype arc presented to validate the feasibility of the proposed Air Blower Motor and Driver.