• Bulletin of the Korean Mathematical Society
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• v.47 no.1
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• pp.73-79
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• 2010

A pair of point vortices of the same strength but opposite sign is called a vortex dipole. We consider the limiting case where two vortices approach infinitely close while the ratio of the strength to the distance kept constant. The motion of such point vortex dipole on the ellipsoid of revolution is investigated geometrically to conclude that the trajectory draws a geodesic up to the leading order of perturbation, whose direction is determined by the initial orientation of the dipole. Related issues are also remarked.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.3
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• pp.321-328
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• 2008

In this paper, a novel log-periodic cantor dipole antenna(LPCDA), which is composed of the cantor-dipole elements instead of the existing dipole elements, is proposed. The proposed antenna makes possible the antenna miniaturization by using the cantor-dipole elements. To investigate the reliability of the proposed antenna, LPCDA is designed and analyzed at $1{\sim}4GHz$ band and compared with LPDA(Log-Periodic Dipole Antenna) characteristics. It is shown that although the elements of LPCDA are 13.3% shorter than LPDA, the gain increases about 2dB and VSWR is less than 2 in at the upper band.

• Journal of the Society of Naval Architects of Korea
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• v.57 no.2
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• pp.114-123
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• 2020

A high-order potential-based panel method based on Green's theorem, with piecewise-linear dipole strength on triangular panels, is formulated for the analysis of potential flow around a three-dimensional wing. Previous low-order panel methods adopt square panels with piecewise-constant dipole strength, which results in inherent errors. Square panels can not represent a high curvature lifting body, such as propellers, since the four vertices of the square panel do not locate at the same flat plane. Moreover the piecewise-constant dipole strength induces inevitable errors due to the steps in dipole strength between adjacent panels. In this paper a high-order panel method is formulated to improve accuracy by adopting a piecewise linear dipole strength on triangular panels. Firstly, the square panels are replaced by triangular panels in order to increase the geometric accuracy in representing the shape of the object with large curvature. Next, the step difference of the dipole strength between adjacent panels is removed by adopting piecewise-linear dipole strength on the triangular panels. The calculated results by the present method is compared with analytical ones for simple non-lifting geometries, such as ellipsoid. The results for an elliptic wing with zero thickness at finite angle of attack are compared with Jordan's results. The comparison shows reasonable agrements for the both lifting and non-lifting bodies.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2013.05a
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• pp.61-62
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• 2013

In this paper, a design method for a compact broadband planar dipole antenna fed by a microstrip (MS) line is studied. The proposed broadband dipole is optimized for terrestrial digital television (DTV) receiving. The dipole is fed by an MS line with 75-ohm characteristic impedance on an FR4 substrate and its size is $90mm{\times}180mm$. The dipole is modified to half bow-tie type for size reduction. A simplified balun is adopted for the impedance matching between the MS line and coplanar strip which feeds the dipole. The optimized dipole antenna for DTV band (470-806 MHz) is fabricated on an FR4 substrate and tested experimentally to verify the results of this study.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.2
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• pp.128.1-128.1
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• 2012

최근 태양주기 21, 22, 23을 지나 24주기로 감에 따라 태양활동의 지표인 태양상수, 행성간 자기장, 태양극자기장 등과 같은 여러 태양물리량들이 감소하여 태양 활동이 약화되었고 23/24주기의 극소기가 길어졌다. 태양 자기장의 극성은 대체로 Dipole의 형태로 근사하여 나타나지만 dipole 뿐만 아니라 Quadrupole 등과 같은 다중극의 합으로 나타난다. 본 연구에서는 Wilcox Solar Observatory (WSO)에서 제공하는 21주기부터 23주기 동안의 총 태양 자기장의 구조화 함수 coefficient의 세기, dipole 성분 및 Multipole 성분의 변화를 분석하였다. 분석 결과 최근 23 태양주기 시작 이후로 총 태양 자기장의 세기가 감소하는 추세를 보이며 21, 22주기에 비해 23주기에 multipole 성분 보다 dipole 성분이 더 큰 감소율을 보여 dipole이 약해지고 multipole이 강해진 것을 알 수 있었다. 그러므로 태양활동 변화에 Multipole 성분도 중요한 역할을 한다고 볼 수 있다. 전반적으로 태양활동 극대기에는 dipole의 세력이 약하고 극소기에는 dipole의 세력이 강하게 나타난다. 또한 태양주기 23/24의 극소기일 때, 다중극 성분 중 특히 Quadrupole 성분이 차지하는 비율이 두드러지게 증가하였다. 태양활동 극소기에 23/24주기처럼 태양활동이 더 저조해지면 상대적으로 quadrupole 성분이 증가하게 되는 것으로 여겨진다. 그러므로, 다음 태양주기 24/25의 극소기에는 태양활동이 더 약해져서 Quadrupole 성분이 더욱 두드러지게 증가하게 될 것으로 예측된다.

• Korean Journal of Optics and Photonics
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• v.13 no.5
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• pp.430-434
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• 2002

We present the magnitude of terahertz electromagnetic pulses when femtosecond laser pulses are moving along to a dipole antenna. The dipole antenna chip has maximum 4.7 nA THz current, generated at 11 DC volt. This current is 3.4 times bigger than the current of a $300{\mu}{\textrm}{m}$ separated transmission line structure chip that has 70 DC volt. We also apply an AC square wave voltage to the dipole antenna from 0.1 volt to 10 volt for binary signals using the terahertz electromagnetic pulses.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.4
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• pp.606-611
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• 2012

The similarity, analogy and equivalence between the phenomenon due to electric and magnetic dipoles have been discussed in the open literature for different situations. Here we are presenting the numerical proof of the trajectory of leakage electric field due to a semi-infinite electric dipole layer in the external periphery and the electric field in the space between oppositely charged surfaces. The result is also valid for the fringing electric field of a parallel plate capacitor. The result is also proved to be a dual of Amp$\grave{e}$re's law in the electrostatics due to a semi-infinite electric dipole layer.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2018.10a
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• pp.526-528
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• 2018

This paper proposes a small, flexible dipole antenna for wireless power transmission of smart devices in a Wi-Fi environment. The proposed antenna is a mini-dipolar antenna structure with a split ring resonator in the center and is a small dipole antenna with a size of 32mm. The split ring resonator dipole antenna showed a reduction of about 20% compared to the same size of the dipole antenna.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.4 no.1
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• pp.59-65
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• 2000

This paper describes the characteristics of a one dimensional narrow-wall slotted waveguide array with a single-layer linear-to-circular polarization converter consisting of a dipole array. An external boundary value Problem of one slot and three dipoles, which approximates the mutual coupling between the dipole array and an edge slot extending over three faces of a rectangular waveguide, is formulated and analyzed by the method of moments; design of polarization conversion is conducted for this model as a unit element. If every unit element has perfect circular polarization, grating lobes appear in the array pattern due to the alternating slot angle: these are suppressed in this paper by changing the dipole angle and degrading the axial ratio of the unit element. The validity of the design is confirmed by the measurements. The dipole array has negligible effects upon slot impedance; the polarization conversion for existing narrow-wall slotted arrays is realized by add-on dipole array.

• Bulletin of the Korean Chemical Society
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• v.7 no.1
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• pp.15-20
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• 1986

Modified technique in calculating the dipole moments for square pyramidal complexes has been developed and then the dipole moments for bisacetylacetonato(oxo)vanadium(Ⅳ) complexes are calculated, adopting this approach. The calculated dipole moments for bisacetylacetonato(oxo)vanadium(Ⅳ) in benzene and bisacetylacetonato(oxo)vanadium in dioxane solutions are in agreement with the observed values. The calculated dipole moments of bisacetylacetonato(oxo)vanadium(Ⅳ) in dioxane solution is slightly higher than that of bisacetylacetonato(oxo)vanadium(Ⅳ) in benzene. Such a result may suggest that bisacetylacetonato(oxo)vanadium(Ⅳ) interact with dioxane molecule to form bisacetylacetonato(oxo)vanadium(Ⅳ)-dioxane adduct. This calculated dipole moments are also in agreement with the experimental results.