• Interaction and multiscale mechanics
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• 제3권2호
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• pp.157-171
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• 2010

In this paper, a theoretical method has been developed for the electric double layer interaction under condition of the variable dielectric permittivity of water. Using Poisson-Boltzmann equation (PBE), for one plate and two plates having similar or dissimilar constant charge or constant potential, we have investigated the electric double layer potential, its gradient and the disjoining pressure as well as the effect of variation of dielectric permittivity on these parameters. It has been assumed that plates are separated by a specific distance and contain a liquid solution in between. It is shown that reduction of the dielectric permittivity near the interfaces results in compression of electric double layers and affects the potential and its gradient which leads to a decreased electrostatic repulsion. In addition, it is shown that variation of dielectric permittivity in the case of higher electrolyte concentration, leads to a greater change in potential distribution between two plates.

• Journal of Electrical Engineering and Technology
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• 제12권5호
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• pp.1729-1742
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• 2017

In designing System Protection Schemes (SPSs) in power systems, protecting transmission network against extreme undesired conditions becomes a significant challenge in mitigating the transmission line overloading. This paper presents an intelligent Special Protection and Control Scheme (SPCS) using of Differential Evolution with Adaptive Mutation (DEAM) approach to obtain the optimum generation rescheduling to solve the transmission line overloading problem in system contingency conditions. DEAM algorithm employs the attraction-repulsion idea that is applied in the electromagnetism-like algorithm to support the mutation process of the conventional Differential Evolution (DE) algorithm. Different N-1 contingency conditions under base and increase load demand are considered in this paper. Simulation results have been compared with those acquired from Genetic Algorithm (GA) application. Minimum severity index has been considered as the objective function. The final results show that the presented DEAM method offers better performance than GA in terms of faster convergence and less generation fuel cost. IEEE 30-bus test system has been used to prove the effectiveness and robustness of the proposed algorithm.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1991년도 하계학술대회 논문집
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• pp.114-117
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• 1991

In magnetic levitation and repulsion systems, the eddy current on the rail induced by the motion of vehicle, plays an important role on forces. The 3-dimensional finite element method is used to analyze these phenomina. The non-linear analysis is also carried out using Newton-Raphson method. The levitation, drag, and guidance forces are compared with those obtained by two-dimensional linear analysis and three-dimensional linear analysis.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2011년도 제42회 하계학술대회
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• pp.914-915
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• 2011

최근 지구온난화의 문제점으로 저 탄소 친환경 자동차로 배터리 전력과 가솔린 엔진을 같이 사용하는 하이브리드 자동차가 주목 받고 있다. 최근에 개발되고 있는 하이브리드 자동차는 전력의 효율적인 사용을 위해 배터리의 전압이 증가되고 있고 이에 따라 DC High Voltage를 다룰 수 있는 Relay의 용량이 요구된다. 이런 측면에서 하이브리드 자동차에 사용되는 EV-Relay의 경우 소형화에 따른 문제점이 발생한다. 그 대표적인 문제점으로 EV-Relay의 접점에 일시적인 과전류가 흐르면서 전기적 반발력이 발생하여 EV-Relay의 폭발과 같은 위험한 문제점이 발생 할 수 있다. 이에 따라 본 논문에서는 Relay에서 발생하는 전기반발력의 힘을 MAXWELL프로그램을 통해 모의하는 연구를 하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 추계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.80-82
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• 2004

This paper deals with design of linear switched reluctance motors(LSRM) which drive a testing machine of eddy current magnetic repulsion system using Halbach array and conducting plate. The design method employing finite element method and parameter estimation method and a characteristic of LSRM according to variation of parameter is introduced.

• 한국응용과학기술학회지
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• 제12권1호
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• pp.1-11
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• 1995

In this outline, the stability of solid/liquid dispersion was theoretically investigated the matter from all angles by using the modified DLVO theory. The stability was handled various considerations such as a production and characteristics of electrical double layer, total interaction$(V_T)$ that consisting of attractive force$(V_A)$ and repulsion$(V_R)$. coagulation, the stability ratio(W), critical flocculation concentration (cfc) and zeta potential$(\zeta)$ etc. It was possible for us to examine with the stability ratio(W), critical flocculation concentration (cfc) and zeta potential$(\zeta)$ that may estimation of stability of solid/liquid dispersion experimentally.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 A
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• pp.357-359
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• 1999

It is necessary for the optimum design of switching devices to calculate repulsion forces acting on the closed electric contacts flowing over-current, e.g. inrush current and overload currents. In this paper, the forces generated by currents and flux densities at the contact point when circuit breakers are in closed position are obtained by using 3D finite element method. According to the analysis, the optimum configuration of wipe springs and arc extinguishing chambers are newly designed and consequently type tests show satisfactory results.

• Food Science and Biotechnology
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• 제18권3호
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• pp.610-617
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• 2009

The stability of corn oil-in-water emulsions coated by milk proteins, sodium caseinate (CAS), or whey protein concentrate (WPC), was compared under the environmental stress of pH change. Emulsions were prepared at 0.1 of protein:oil because the majority of droplets were relatively small ($d_{32}=0.34$ and $0.35\;{\mu}m$, $d_{43}=0.65$ and $0.37\;{\mu}m$ for CAS- and WPC-emulsions, respectively) and there was no evidence of depletion flocculation. As the pH of the emulsions was gradually dropped from 7 to 3, there was no significant difference in the electrical charges of the emulsion droplets between the 2 types of emulsions. However, laser diffraction measurements, microscopy measurements, and creaming stability test indicated that WPC-emulsions were more stable to droplet aggregation than CAS-emulsions under the same circumstance of pH change. It implies that factors other than electrostatic repulsion should contribute to the different magnitude of response to pH change.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1999년도 춘계학술대회 논문집
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• pp.345-348
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• 1999

The monolayer behaviors at the air-water interface and the dielectric properties of MI-0 LB films for complex concentration were investigated by the surface pressure-area ($\pi$-A) isotherms and dielectric constant. The molecular area was expanded with increase of metal ions concentration. It is considered that the expansion of molecular area is due to electrostatic repulsion between the polymer chains andhydrophobic increase of ionic strength. In the frequency-dependent complex dielectric constant at room temperature, the real part of dielectric constant($\varepsilon'$) is about 6.0~10.0 in the low-frequency range and is decreasing slowly upto $1O^4$Hz. It decreased abruptly near $1O^5Hz$. It seems to be dielectric dispersion in this frequency range. Also, the imaginary part of dielectric constant ($\varepsilon"$) shows a peak in $1O^5$~$1O^6Hz$. It seems to be dielectric absorption in this frequency range.ange.

• Environmental Analysis Health and Toxicology
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• 제28권
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• pp.6.1-6.7
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• 2013

Objectives In this study, we investigated the influence of ionic strength and natural organic matter (NOM) on aggregation and soil adsorption of citrate-coated silver nanoparticles (AgNPs). Methods Time-resolved dynamic light scattering measurements and batch adsorption experiments were used to study their aggregation and soil adsorption behaviors, respectively. Results The aggregation rate of AgNPs increased with increasing ionic strength and decreasing NOM concentration. At higher ionic strength, the AgNPs were unstable, and thus tended to be adsorbed to the soil, while increased NOM concentration hindered soil adsorption. To understand the varying behaviors of AgNPs depending on the environmental factors, particle zeta potentials were also measured as a function of ionic strength and NOM concentration. The magnitude of particle zeta potential became more negative with decreasing ionic strength and increasing NOM concentration. These results imply that the aggregation and soil adsorption behavior of AgNPs were mainly controlled by electrical double-layer repulsion consistent with the Derjaguin-Landau-Verwey-Overbeek theory. Conclusions This study found that the aggregation and soil adsorption behavior of AgNPs are closely associated with environmental factors such as ionic strength and NOM and suggested that assessing the environmental fate and transport of nanoparticles requires a thorough understanding of particle-particle interaction mechanisms.