• 한국전자파학회:학술대회논문집
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• 한국전자파학회 2002년도 종합학술발표회 논문집 Vol.12 No.1
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• pp.340-343
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• 2002

Electromagnetic(EM) radiation problems and their possible solutions are addressed in this paper for the split power plane of high-speed digital systems. Stitching and decoupling capacitors are proved to be very effective fur reducing signal noise, ground bounce as well as electromagnetic radiation from the split power plane. Simulations based on 3D-Finite Difference Time Domain (FDTD) method are utilized for the analysis of practical high frequency multi-layered PC main board

• Journal of electromagnetic engineering and science
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• 제2권2호
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• pp.75-80
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• 2002

Signal integrity problems and their possible solutions are addressed in this paper for split power plane of high-speed digital systems. Stitching and decoupling capacitors are proved to be very effective for reducing signal noise, ground bounce as well as electromagnetic radiation from the split power plane. Simulations based on 3D-Finite Difference Time Domain (FDTD) method are utilized for the analysis of practical high frequency multi-layered PC main board.

• Journal of Power Electronics
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• 제11권4호
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• pp.401-407
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• 2011

In order to enhance torque density of five-phase permanent magnetic synchronous motor with third harmonic injection for electric vehicles (EVs) applications, optimum seeking method for injection ratio of third harmonic was proposed adopting theoretical derivation and finite element analysis method, under the constraint of same amplitude for current and air-gap flux. By five-dimension space vector decomposition, the mathematic model in two orthogonal space plane, $d_1-q_1$ and $d_3-q_3$, was deduced. And the corresponding dual-plane vector control method was accomplished to independently control fundamental and third harmonic currents in each vector plane. A five-phase PMSM prototype with quasi-trapezoidal flux pattern and its fivephase voltage source inverter were designed. Also, the dual-plane vector control was digitized in a single XC3S1200E FPGA. Simulation and experimental results prove that using the proposed optimum seeking method, the torque density of five-phase PMSM is enhanced by 20%, without any increase of power converter capacity, machine size and iron core saturation.

• 한국전자파학회논문지
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• 제20권12호
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• pp.1272-1278
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• 2009

본 논문은 신호 전송용 비아가 있는 4층 PCB(Printed Circuit Boards)의 P/G(power/ground)면 사이에서 발생되는 공진을 상쇄시켜 복사성 방사(RE: Radiated Emission) 성능을 개선할 수 있는 기법을 제안하였다. 면간 공진 상쇄를 확인하기 위하여 비아가 있는 4층 PCB에서 신호 전송 선로의 전송 특성, PCB 개방 모서리를 통한 방사(radiation)와 RE 세기를 계산하고, 측정하여 제안된 기법의 타당성을 입증하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 추계학술대회 논문집 학회본부
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• pp.534-537
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• 1997

Solar power systems have become popular in the modem electric energy system. In order to supply the DC power, generated by solar cells, to the electric power system, the solar power system requires DC-to-AC power conversion. A line-commutated inverter or a forced-commutated inverter can be used in the DC-to-AC power conversion. Because of the nonlinear V-I characteristics of the solar cells, multiple operating points determined by the control mode of the inverter exist in the DC V-I state plane of the solar power system. In this paper, the stability of utility-interactive solar power system with a line-commutated inverter is analyzed at various operating points, using the eigenvalue method and the state-plane analysis technique. The stability of a forced-commutated inverter case is also anaiyzed and compared to that of the line-commutated inverter case.

• 한국ITS학회 논문지
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• 제15권5호
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• pp.108-115
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• 2016

본 논문에서는 배열 합성 혼 안테나를 설계하고 고출력 마그네트론을 연결하여 방사전력을 측정하였다. 제안된 안테나는 $4{\times}4$ 배열 합성 혼 안테나 특성을 바탕으로 후방 방사를 억제시키기 위해 합성 혼 개구면 상, 하단에 2단 단락구조물을 부착하여 빔폭 E-plane $8.86^{\circ}$, H-plane $7.35^{\circ}$, 전후방비 39.7 dB를 얻었다. 또한 배열된 마그네트론을 이용한 배열 혼 안테나의 방사전력을 측정하기 위하여 도파관 어댑터를 설계하여 마그네트론과 혼 안테나를 연결 시켰고 고출력의 파워를 측정하기 위해 중간단에 에어갭을 넣은 마이크로스트립 라인 커플러를 설계하였다. $4{\times}4$ 배열 합성 혼 안테나의 중앙에 4개의 마그네트론을 연결하여 측정한 결과 평균 방사 출력 0.063 W를 얻었다.

• 대한수학회보
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• 제60권2호
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• pp.507-514
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• 2023

Suppose that a line passing through a given point P intersects a given circle 𝓒 at Q and R in the Euclidean plane. It is well known that |PQ||P R| is independent of the choice of the line as long as the line meets the circle at two points. It is also known that similar properties hold in the 2-sphere and in the hyperbolic plane. New proofs for the similar properties in the 2-sphere and in the hyperbolic plane are given.

• 한국환경과학회지
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• 제20권7호
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• pp.839-843
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• 2011

We have established a wind map of Singapore, a city-state characterized its land cover by urban buildings to confirm a possibility of wind farm development. As a simple but useful approximation of urban canopy, a zero-plane displacement concept was employed. The territory is divided into 15 sectors having similar urban building layouts, and zero-plane displacement, equivalent roughness height at each sector was calculated to setup a terrain boundary condition. Annual mean wind speed and mean wind power density map were drawn by a CFD micrositing model, WindSim where Changi International Airport wind data was used as an in-situ measurement. Unfortunately, predicted wind power density does not exceed 80 $W/m^2$ at 50 m above ground level which would not sufficient for wind power generation. However, the established Singapore wind map is expected to be applied for wind environment assessment and urban planning purpose.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2001년도 춘계학술대회 논문집
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• pp.1085-1088
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• 2001

The process of styrofoam pattern that has been used for material of press die pattern depends chiefly on handwork. Laser manufacturing system developed to increase precision and efficiency of process that is also able to convert the design easily. Applying the RP(rapid prototyping) concept reversely, the unnecessary part of section is vapored away by heat source of laser beam after converting 3-D CAD model into cross-sectional shape information. Laser beam is line-scanned in plane specimens to measure the depth and width of cut, surface roughness, cross-sectional shape as converting laser power, scanning speed, cutting gas pressure. With these basic data, plane surface, inclined surface, hole, outer contour trimming process is experimented and optimum condition are obtained. In plane and inclined surface experiments, 15W laser power and 50mm/s scanning speed make superior processing property and 30W, 10mm/s make processing efficiency increase in trimming process. With these results, simple patterns were manufactured and the possibility of applying laser manufacturing system to styrofoam pattern was convinced.

• 한국전기전자재료학회논문지
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• 제18권5호
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• pp.457-463
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• 2005

This paper presents a method for analyzing irregular shaped power distribution networks. The irregular shaped metal-dielectric-metal plane is split into several piece of rectangular segments to calculate the impedance of the irregular shaped plane. Impedance matrix for each rectangular segments is calculated using the Mobius transform method to reduce the calculation time. Then the segmentation and do-segmentation method is applied to the piece of rectangular segments. Applied to the 6 inch by 5 inch size irregular shaped board, the proposed method shows 10 times faster than the electromagnetic or circuit analysis method.