• Bulletin of the Korean Chemical Society
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• 제11권6호
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• pp.487-493
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• 1990

A complete potential profile of an electrical double layer is calculated from a distribution function of charged particles based upon a model where the effect of a charged electrode and the finite size of ion are explicitly included. Electrons which are distributed on the electrode surface are assumed not to penetrate the electrode/electrolyte boundary. Formation of the constant density regions and their effects on potential and the electrical double layer capacitances are studied in great detail. The distribution of surface electrons as well as the constant density regions are found to be essential in characterizing the electrical double layer. The introduction of the ion size into the prior electrical double layer model of an ideally polarizable electrode/point charged electrolyte system, shows a great improvement in its characteristics mostly at negative potential region.

• 전기학회논문지
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• 제67권4호
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• pp.554-560
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• 2018

Since Korea has a small land area, it is expected to construct the conductor return type with neutral wire in the case of ${\pm}500kV$ HVDC double bipole transmission line. Therefore, in order to apply ${\pm}500kV$ HVDC double bipole transmission line with neutral wire in Korea, it is necessary to develop technology for insulation and environmental designs. In this study, radio interference, audible noise, electric field and ion current density according to the polarity arrangement were compared and assessed in the ${\pm}500kV$ HVDC double bipole transmission line with the conductor return method. And the optimum configuration of HVDC double bipole transmission line was determined from the viewpoint of electrical environment.

• 디지털산업정보학회논문지
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• 제8권3호
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• pp.133-145
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• 2012

This paper describes the high density discrete wavelet transformation which is one that expands an N point signal to M transform coefficients with M > N. The double-density discrete wavelet transform is one of the high density discrete wavelet transformation. This transformation employs one scaling function and two distinct wavelets, which are designed to be offset from one another by one half. And it is nearly shift-invariant. Similarly, triple-density discrete wavelet transformation is a new set of dyadic wavelet transformation with two generators. The construction provides a higher sampling in both time and frequency. Specifically, the spectrum of the first wavelet is concentrated halfway between the spectrum of the second wavelet and the spectrum of its dilated version. In addition, the second wavelet is translated by half-integers rather than whole-integers in the frame construction. This arrangement leads to high density wavelet transformation. But this new transform is approximately shift-invariant and has intermediate scales. In two dimensions, this transform outperforms the standard and double-density discrete wavelet transformation in terms of multiple directions. Resultingly, the proposed wavelet transformation services good performance in image and video processing fields.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 추계학술대회 논문집 전력기술부문
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• pp.46-50
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• 2004

This paper analysed the induced current density inside human body of hot-line worker for 765kV double circuit transmission line according to locations of human body Human was modelled by several organs, which included brain, heart, lungs, liver and intestines. We applied the 3 dimensional boundary element method to calculate induced electric fields.

• 대한교통학회지
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• 제31권5호
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• pp.48-59
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• 2013

본 연구에서는 도로투자 사업으로 인한 편익 중 일반적으로 계상하고 있는 통행시간 절감 및 차량운행비용 절감 등 직접적인 편익 이외에 추가적으로 이용자입장에서 체감할 수 있는 도로 주행 중 운전쾌적성 편익을 산정하고자 운전쾌적성의 정의를 마련하였고 운전쾌적성 산정방법론을 개발하였다. 도로특성(도시부/지방부) 및 차량 밀도(차간거리)에 따른 이용자의 지불용의액을 CVM 방법 중 가장 최근에 활발히 활용되고 있는 이중양분선택형(double-bounded dichotomous choice)질문법을 활용하여 설문조사한 후 그 결과를 로짓모형에 적용하여 운전쾌적성 가치를 도출하였다. 도시부 및 지역간 도로에서 공히 지불용의액의 크기는 전반적으로 기존 차간거리가 짧을수록 큰 것으로 분석되었고, 도로의 차간거리 변화가 같더라도 사업 전의 차간거리와 사업 후의 차간거리에 따라 지불용의액이 다른 것으로 나타났다. 즉, 도로의 차간거리가 증가하더라도 기존 차간거리가 어느 정도인지에 따라 지불용의액이 다르게 나타나 지불용의액이 기존 차간거리에 영향을 받는 것으로 분석되었다.

• 전력전자학회논문지
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• 제21권5호
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• pp.381-387
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• 2016

Many efforts have focused on the improvement of power density and efficiency by downsizing the motor and inverter. Recently, Toyota, Honda, and GM realized that the compact-sized motor uses the hairpin structure with increased space factor. Reducing the maximum torque from high-speed technique also makes it possible to design the high-power density model. Toyota and Honda used the newly developed power semiconductor IGBT to decrease conduction loss for high-efficiency inverter. In particular, Toyota used the boost converter to increase the DC link voltage for high efficiency in low-torque high-speed region. Toyota and GM also used the double-sided cooling structure for miniaturization of inverter for high-power density.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• 제11권1호
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• pp.71-83
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• 2007

The double diffusive convection of cold water in the vicinity of its density maximum in a rectangular partitioned enclosure of aspect ratio 5 with isothermal side walls and insulated top and bottom is studied numerically. A thin partition is attached to the hot wall. The species diffusivity of the fluid is assumed to vary linearly with concentration. The governing equations are solved by finite difference scheme. The effects of position and height of the partition, variable species diffusivity and enclosure width are analyzed for various hot wall temperatures. It has been found that adding partition on the hot wall reduces the heat transfer. The density inversion of the water has a great influence on the natural convection. When increasing species diffusivity parameter heat and mass transfer rate is decreased.

• Communications for Statistical Applications and Methods
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• 제17권3호
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• pp.451-457
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• 2010

This paper considers the problem of nonparametric deconvolution density estimation when sample observa-tions are contaminated by double exponentially distributed errors. Three different deconvolution density estima-tors are introduced: a weighted kernel density estimator, a kernel density estimator based on the support vector regression method in a RKHS, and a classical kernel density estimator. The performance of these deconvolution density estimators is compared by means of a simulation study.

• Bulletin of the Korean Chemical Society
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• 제32권6호
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• pp.1851-1858
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• 2011

Details of the double-bond isomerization of 1-hexene over H-ZSM-5 were clarified using density functional theory. It is found that the reaction proceeds by a mechanism which involves the Br${\o}$nsted acid part of the zeolite solely. According to this mechanism, 1-hexene is first physically adsorbed on the acidic site, and then, the acidic proton transfers to one carbon atom of the double bond, while the other carbon atom of the double bond bonds with the Br${\o}$nsted host oxygen, yielding a stable alkoxy intermediate. Thereafter, the Br${\o}$nsted host oxygen abstracts a hydrogen atom from the $C_6H_{13}$ fragment and the C-O bond is broken, restoring the acidic site and yielding trans-2-hexene. The calculated activation barrier is 12.65 kcal/mol, which is in good agreement with the experimental value. These results well explain the energetic aspects during the course of double-bond isomerization and extend the understanding of the nature of the zeolite active sites.

• 전기화학회지
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• 제25권1호
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• pp.32-41
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• 2022

Various steps in the electrode production process, such as slurry mixing, slurry coating, drying, and calendaring, directly affect the quality and, consequently, mechanical properties and electrochemical performance of electrodes. Herein, a new method of slurry coating is developed: Double-coated electrode. Contrary to single-coated electrode, the cathode is prepared by double coating, wherein each coat is of half the total loading mass of the single-coated electrode. Each coat is dried and calendared. It is found that the double-coated electrode possesses more uniform pore distribution and higher electrode density and allows lesser extent of particle segregation than the single-coated electrode. Consequently, the double-coated electrode exhibits higher adhesion strength (74.7 N m^-1) than the single-coated electrode (57.8 N m^-1). Moreover, the double-coated electrode exhibits lower electric resistance (0.152 Ω cm^-2) than the single-coated electrode (0.177 Ω cm^-2). Compared to the single-coated electrode, the double-coated electrode displays higher electrochemical performance by exhibiting better rate capability, especially at higher C rates, and higher long-term cycling performance. Despite its simplicity, the proposed method allows effective electrode preparation by facilitating high electrochemical performance and is applicable for the large-scale production of high-energy-density electrodes.