• 한국초전도ㆍ저온공학회논문지
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• 제13권4호
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• pp.26-29
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• 2011

In a High temperature superconducting (HTS) tape with high aspect ratio, the magnetic field applied to the HTS tape can be different considerably within the HTS tape. The current distribution in the HTS tape is generally non-uniform because the current distribution is strongly dependent on the applied magnetic field. Non-uniform current distribution in a HTS tape has not been properly considered when the critical current has been estimated. This paper shows the calculation of critical current of a HTS magnet consisting of pancake windings. Non-uniform distribution of current in the HTS tape is considered during the calculation of the critical current. Results of calculation show the current concentrated in the middle part of the HTS tape which is used for one pancake winding.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 E
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• pp.2299-2301
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• 1999

In this work, experimental investigation was carried out for the breakdown characteristics of $SF_6$, $N_2$ and their mixtures under the uniform and non-uniform electric field, by use of HVAC and standard impulse testing voltages, as a function of different gas pressures from 1 atm to 5 atm. The results show that the dielectric strength of the $SF_6$ mixed in $N_2$ was significantly increased at its portion of 10%, which might imply that the optimum mixture of $SF_6$ for the HV switch gear could be proposed to be 10%.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 하계학술대회 논문집 Vol.8
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• pp.462-463
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• 2007

SF6 widely used as insulating gas is rising as the environment problem. For decreasing this greenhouse gas, electrical breakdown characteristics of composite insulation composed of epoxy resins with N2, air are studied in non-uniform field. The gap of needle to plane was 3mm, 5mm. The pressure of air, nitrogen was varied within the range of 0.1~0.6MPa. The thickness of a needle is 1mm and the curvature radius of the end of needle is 100um. The diameter of a plane made of the stainless steel is 50mm. As a result of the experiment, the breakdown voltage is increased about 3 times when epoxy resins is composited. The thickness of epoxy resins filled opposite to electrode concentrated electric field weakly influences on breakdown voltage.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2004년도 제22회 춘계학술대회논문집
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• pp.69-74
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• 2004

In scramjet engines with sidewall compression inlet, it is well known that a non-uniform flow appears since a separated region is generated near the flow centerline on the body side. The separated region is caused by shock-boundary layer interaction and likely to cause un-start phenomena since the flow in the separated region is subsonic and acts as a communication path between the isolator and the combustor. In the present study, the non-uniform flow characteristics in the scramjet inlet-isolator region are numerically studied in detail. Effect of flow suction from body sidewall surface on the non-uniform flow field numerically examined to clarify the flow mechanism to suppress the un-start transition.

• 조명전기설비학회논문지
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• 제17권6호
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• pp.77-82
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• 2003

본 논문에서는 강한 불평등전계를 형성시킬 수 있는 다선형전극을 강전해수 발생장치내에 설치하여 전계집중효과에 의해 발생되는 기포내의 선행방전의 형태와 기포방전이 수소이온농도와 산화환원전위반응에 미치는 영향을 검토하고자 하였다. 실험결과, 강전해수 발생장치내의 양전극측을 다선형으로 함으로써 양전극측에서 발생되는 기포내에서 비유전율 차이에 의한 기포내의 선행방전을 관찰할 수 있었다. 그리고 기포방전에 의해 발생된 이온들이 강전해수 발생장치내에 용해됨으로써 전해수의 이온농도를 증가시켰다. 이때 발생된 고농도의 이온들을 분리집속 시키고 산화환원작용을 크게 증가시켜 고농도의 강전해수를 발생시킬 수 있었다.

• 조명전기설비학회논문지
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• 제15권5호
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• pp.20-27
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• 2001

본 연구에서는 평등 및 불평등 전계하에서 58.8~137.3[kPa]의 가스 압력변화에 따른 순수 Ar 및 $N_2$가스의 교류절연파괴 특성을 조사하였다. 그리고 가스 압력 변화에 따른 Ar/$N_2$ 혼합 가스의 교류절연파괴 특성과 비교하였다. 실험 결과를 요약하면, 평등 및 불평등 전계하에서 순수 $N_2$가스의 압력 변화에 따른 교류절연파괴 특성은 순수 Ar 가스에 비해 약 4.8배 1.1배 증가된 것으로 나타났으며, 압력이 증가됨에 따라 교류절연파괴전압은 증가되었다. Ar/$N_2$혼합 가스의 절연파괴전압은 순수 $N_2$가스의 혼합비가 적을수록 감소되었으며, 혼합 가스 압력이 101.3[kPa]일 때, 순수 Ar 가스에 비해 Ar 가스 혼합 비율이 각각 85[%] 및 70[%] 인 경우, 교류절연파괴전압은 평등 전계하에서는 약 1.5 및 2.1배 증가되었으며, 불평등 전계하에서는 약 1.1 및 1.3배 증가되었다. 또한 불평등 전계하에서 Ar(70%)$N_2$(30%) 혼합 가스의 코로나개시전압은 순수 Ar 가스에 비해 약 1.5배 증가되었다.

• 전기학회논문지P
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• 제66권3호
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• pp.139-143
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• 2017

In this paper, we propose a separation method of the dielectric particles in the liquid flow. Since particles are dielectric in most cases, they experience dielectrophoretic(DEP) force under non-uniform electric field. The field characteristics in the electromagnetic and fluid dynamic systems are solved by using the finite element method. The motional equation of the particles is calculated by the Runge-Kutta method. The field analysis shows the feasibility of the proposed method. The particle separation model with large DEP force exerting on particles is designed by analyzing field characteristics.

• 한국유체기계학회 논문집
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• 제11권6호
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• pp.46-53
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• 2008

Flow structures in an axial compressor with a non-uniform tip clearance were predicted by solving a simple prediction method. For more reliable prediction at the off-design condition, off-design flow characteristics such as loss and flow blockage were incorporated in the model. The predicted results showed that flow field near the design condition is largely dependent on the local tip clearance effect. However overall flow field characteristics are totally reversed at off-design condition, especially at the high flow coefficient. The tip clearance effect decreases, while the local loss and flow blockage make a complicated effect on the compressor flow field. The resultant fluid induced Alford's force has a negative value near the design condition and it reverses its sign as the flow coefficient increases and shows a very steep increase as the flow coefficient increases.

• 대한수학회보
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• 제51권4호
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• pp.1087-1100
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• 2014

We present an accurate and efficient numerical method for solving the Black-Scholes equation. The method uses an adaptive grid technique which is based on a far-field boundary position and the Peclet condition. We present the algorithm for the automatic adaptive grid generation: First, we determine a priori suitable far-field boundary location using the mathematical model parameters. Second, generate the uniform fine grid around the non-smooth point of the payoff and a non-uniform grid in the remaining regions. Numerical tests are presented to demonstrate the accuracy and efficiency of the proposed method. The results show that the computational time is reduced substantially with the accuracy being maintained.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2006년 제4회 한국유체공학학술대회 논문집
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• pp.171-174
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• 2006

When two particles close to each other are in electrophoretic motion, each particle is under the influence of the non-uniform electric field generated by the other particle. Two particles may attract or repel each other due to the dielectric force depending on their positions in the non-uniform electric field. It is shown analytically that two adjusting rigid particles can form an aggregate due to the dielectric interaction. To verify the validity of the theoretical prediction, an experiment is carried out by using a microchannel. In the experiment, AC electric field is used to eliminate cumbersome electroosmotic flow. The experimental result shows that the particles form a chain-like structure, which is typically observed in electro-rheological fluid, due to the dielectric interaction.