• Proceedings of the KIEE Conference
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• 1997.07e
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• pp.1712-1714
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• 1997

This paper deals with the surge counter drived by lightning and switching currents. In order to install the effective surge protective devices, it is important to find the parameters of incident surges. In this paper, for the purpose of protecting the electronic circuits and counting the occuring frequency, the current driving type surge counter is designed and fabricated. The surge counter consists of surge protective divices, current detector, metal oxide varistor(MOV), rectifier, capacitor, and electromagnetic counter. This surge counter is able to count the occuring frequency of surges and to clamp lightning surge current. To evaluate the performance of the surge counter, impulse voltage and current were applied at the surge counter by the surge generator. As a result, applied surges were exactly counted and clamped.

• The Bulletin of The Korean Astronomical Society
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• v.43 no.2
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• pp.45.2-45.2
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• 2018

Twisted magnetic flux tubes (also called magnetic flux ropes) are believed to play a crucial role in solar eruptive phenomena. The evolution of a single flux rope with or without the influence of an overlying field of a simple geometry has been extensively studied and its physics is rather well understood. Observations show that interacting flux tubes are often involved in solar eruptions. It was Lau and Finn (1996) who intensively studied the interaction between two flux ropes, whose footpoints are anchored in two parallel planes. In this too simplified setting, the curvature of the flux rope axial fields is totally ignored. In our study, the footpoints of flux ropes are placed in a single plane containing a polarity inversion line as in the real solar active region. Our simulation study is performed for four cases: (1) co-axial field and co-axial current (co-helicity), (2) counter-axial field and co-axial current (counter-helicity), (3) co-axial field and counter-axial current (counter-helicity), and (4) counter-axial field and counter-axial current (co-helicity). Except case 3, each case is found to be related with certain eruptive features.

• Bulletin of Food Technology
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• v.22 no.1
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• pp.110-116
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• 2009

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.05b
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• pp.30-33
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• 2004

A surge counter is installed under surge arrester, which is protecting the power system apparatuses against abnormal voltage and surges originated in power system line. A surge counter is the device of knowing the times of surge flowed in. There are two methods to get the electric power for mechanical movement and detect the surge. One is using ZnO varistor resister and the other is using the current transformer. In this paper, the characteristics of these methods are presented with using the test and evaluation of them. The process of evaluating the characteristics is essential to develop the domestic surge counter.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07b
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• pp.1134-1137
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• 2004

The main function of surge counter is knowing the times of surge flowed in, which is installed under surge arrester. Two methods are presented in this paper to get the electric power for mechanical movement and detect the surge with surge counter. One is using ZnO varistor resister and the other is using the current transformer.

• Journal of Sensor Science and Technology
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• v.21 no.1
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• pp.1-6
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• 2012

Using a current-mode multiple reset, a current-to-voltage(I-V) converter with a wide dynamic range was produced. The converter consists of a trans-impedance amplifier(TIA), an analog-to-digital converter(ADC), and an N-bit counter. The digital output of the I-V converter is composed of higher N bits and lower bits, obtained from the N-bit counter and the ADC, respectively. For an input current that has departed from the linear region of the TIA, the counter increases its digital output, this determines a reset current which is subtracted from the input current of the I-V converter. This current-mode reset is repeated until the input current of the TIA lies in the linear region. This I-V converter is realized using 0.35 ${\mu}m$ LSI technology. It is shown that the proposed I-V converter can increase the maximum input current by a factor of $2^N$ and widen the dynamic range by $6^N$. Additionally, the I-V converter is successfully applied to a photometric sensor.

• Proceedings of the KSME Conference
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• 2001.06e
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• pp.229-234
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• 2001

An adiabatic counter-current vertical two-phase flow of air and water in narrow rectangular channels with offset strip fm was investigated experimentally. Tests were systematically performed with downward liquid superficial velocities and upward gas velocities covering 0 to 0.06 m/s and 0 to 2.5 m/s ranges, respectively. Two-phase flow regimes were classified by examining the video images of flow patterns in transparent test sections of 760 mm long and 100 mm wide channel with gaps of 3.0 and 5.0 mm. The channel average void fraction was measured by the quick-closing valve method. Unlike the flow regimes in the channels without fin, where bubbly, slug, chum, and annular flow were identified, only bubbly and chum flow regimes were found for the channels with offset strip fin. However the existence of fin in the channels showed negligible effects on the void fraction. Instead counter-current flow limitations were found to happen at lower air superficial velocity once offset strip fin was introduced in narrow rectangular channels.

• Nuclear Engineering and Technology
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• v.34 no.4
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• pp.396-405
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• 2002

An experimental study on counter-current flow limitation phenomena in narrow annular passages was carried out The gap sizes tested were 1, 2 and 3 mm. This is very small compared with the outer diameter of the annular passage, 500 mm. It was visually observed that a CCFL might occur in some part of the periphery while the other part is remained in a counter current flow pattern. That is, non-uniform behaviour of fluids due 4o a 2-dimensional effect appear in a large diameter facility. Because of this non-uniformity, a CCFL is defined in the present work as the situation where net water accumulation is sustained. That is, some amount of water should not be allowed to penetrate the gap and accumulate over the gap at CCFL criterion. The measured data are presented in the form of Wallis＇type correlation with characteristic length of gap size. It was found that the present correlation is in good agreement with other empirical correlation based on measurements whose test section diameter is close and the gap size is much larger than that of the present test section.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.1 no.1
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• pp.15-22
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• 2000

There are lots of industrial machines of which functions are achieved by operation of multi-phase fluids. Some of them take advantage of the characteristics of counter-current two-phase flow The maximum flow rates of gas and liquid phases which flow in opposite-directions (counter-current flow) are limited by a phenomenon known as a Counter-Current Flow Limitation (CCFL or Flooding) The mass and momentum conservation equations for each Phase were established to build a first-order hyperbolic partial derivative equations system. A new CCFL model is developed based on the characteristic equation of the hyperbolic PDE system. The present model has its applicationto the case in which a non-uniform flow is developed around a square or sharp-edged entrance of liquid phase. The model is able to he used to Predict the operating-limit of components in which mass and heat transfer are taking place between liquid and gas phases.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.26 no.3
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• pp.209-215
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• 2013

DSSCs electrical characteristics and efficiency fabricated with different tape casting thickness Pt counter electrodes and different thickness between $TiO_2$ photo electrode and Pt counter electrode substrate were studied. 1 layer Pt counter electrode shows 3.979% efficiency. Efficiency increased as tape casting thickness decreased. The lowest open-circuit voltage was a 0.726 V and the highest short-circuit current was a 2.188 mA on 1 layer Pt counter electrode. On the different thickness between two substrates, the lowest open-circuit voltage 0.712 V and the highest short-circuit current 2.787 mA was measured at $60{\mu}m$ surlyn film thickness and it shows the highest value of 5.067% efficiency.