• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 하계학술대회 논문집 E
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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.

• 천문학회보
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• 제43권2호
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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.

• 식품기술
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• 제22권1호
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• pp.110-116
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• 2009

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 춘계학술대회 논문집 방전 플라즈마 유기절연재료 초전도 자성체연구회
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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.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 하계학술대회 논문집 Vol.5 No.2
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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.

• 센서학회지
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• 제21권1호
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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.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집E
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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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• 제34권4호
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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.

• 한국산학기술학회논문지
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• 제1권1호
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• pp.15-22
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• 2000

다상유체의 작동에 의해서 그 기능을 수행하는 산업기계는 매우 광범위하게 이용된다. 이들 중 일부는 서로 분리된 2상 유체가 반대방향으로 흐르는 특성을 이용하고 있다. 서로 반대방향으로 흐르는 액체상과 기체상의 최대 유량은 역류유동제한 현상으로 제한된다. 이상유동의 질량 및 운동량 보존 방정식을 세우고 쌍곡선형 방정식이 시스템의 특성방정식으로부터 역류유동제한 현상을 예측할 수 있는 모델을 개발하였다. 현재의 모델은 액체상 유입부의 기하학적 모양이 수직이거나 이와 유사한 형태로 되어 있어서 주변에 비등류가 형성되는 경우에 적용된다. 이 모델은 액체와 기체 사이의 질량전달을 일으키는 기계에 대한 유체역학적 운전제한 조건으로 이용될 수 있다.

• 한국전기전자재료학회논문지
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• 제26권3호
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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.