• 한국재료학회:학술대회논문집
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• 한국재료학회 2000년도 추계학술발표강연 및 논문개요집
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• pp.84-84
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• 2000

• 한국정보기술응용학회:학술대회논문집
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• 한국정보기술응용학회 2005년도 6th 2005 International Conference on Computers, Communications and System
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• pp.35-38
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• 2005

In this paper, a wideband balun of tapered structure using planar microstrip is desigde ad analyzed. The balun structure was fabricated on a Teflon substrate with a thickness of 0.8mm and relative dielectric constant ${\varepsilon}_r$ of 2.5. Two back-to back CPW-to-CPS transitions were simulated and optimized using HFSS. A movel plaar balun using tapered structure of microstip to CPW is suggested and designed. The measurement result, the bandwidth for a reflection coefficient better than -10dB of the balun is 2GHz to 8GHz. The planar balun can improved the performance of wide band spiral antenna.

• 한국연소학회:학술대회논문집
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• 한국연소학회 1997년도 제15회 KOSCO SYMPOSIUM 논문집
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• pp.13-21
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• 1997

Excitations of eight pumping transitions for nitric oxide fluorescence imaging are analyzed under equivalent experimental conditions to determine the detection. Frequency mixed dye laser pumping, 1st anti-Stokes $H_2$ Raman of KrF excimer laser pumping and ArF excimer laser pumping show good sensitivities.

• Journal of Mechanical Science and Technology
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• 제15권12호
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• pp.1808-1815
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• 2001

The characteristics of a pulsed plasma jet originating from an electrothermal capillary discharge have been investigate using laser-induced fluorescence (LIF) measurement. Previous emission measurements of a 3.1 kJ plasma jet show trial upstream of the Mach disk the temperature and electron number density are about 14,000 K and and 10$\^$17/ cm$\^$-3/, while downstream of the Mach dick tole values are about 25,000 K and 10$\^$18/ cm$\^$-3/, respectively. However, these values are barred on line-of-sight integrated measurements that may be misleading. Hence, LIF is being used to provide both spatially and temporally resolved measurements. Our recent work has been directed at using planar laser-induced fluorescence (PLIF) imaging of atomic copper in the plasma jet flow field. Copper is a good candidate for PLIF studies because it is present throughout the plasma and has electronic transitions that provide an excellent pump-detect strategy. Our PLIF results to date show that emission measurements may give a misleading picture of the flow field, as there appeals to be a large amount of relatively low temperature copper outside the barrel shock. which may lead to errors in temperature inferred from emission spectroscopy. In this paper, the copper LIF image is presented and at the moment, relative density of atomic copper, which is distributed in the upstream of the pulsed plasma jet, is discussed qualitatively.

• 한국군사과학기술학회지
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• 제6권2호
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• pp.73-82
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• 2003

For measurements and analysis of dielectric characteristics of planar slabs of microwave absorbing materials, I have applied a free-space method in the frequency range of 8~14 GHz. The measurement system for free-space method consists of transmit and receive antennas, mode transitions, precision coaxal cables, the network analyzer, and a computer Special Spot-focused horn lens antenna was used to eliminate diffraction effects. Diffraction effects at the edges of the sample are minimized by satisfying the condition for minimum transverse dimension of the plate and the beamwidth of the antennas at the focus. The time-domain gating feature of the network analyzer and the thru, reflect, and line(TRL) calibration technique were used to eliminate the effects of undesirable multiple reflections. The complex coefficients of reflection and transmission, $S_{11}$ and $S_{21}$, of planar samples were measured for standard materials such as Teflon, Rexolite$\textregistered$ 2200. The results were compared with existing measurement method. And I applied a free-space method for measurement to measure dielectric constants of some electromagnetic absorbing materials. Dielectric properties for the same samples were also measured with a 7mm coxial transmission line method for purposes of comparison with the free-space method.

• 조명전기설비학회논문지
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• 제25권3호
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• pp.40-49
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• 2011

This paper presents novel circuit topology of half-bridge soft-switching PWM inverter type DC-DC high power converter for DC bus feeding power plants. The proposed DC-DC power converter is composed of a typical voltage source-fed, half-bridge high frequency PWM inverter with a high frequency planar transformer link PWM control scheme and parallel capacitive lossless snubbers. The operating principle of the new DC-DC converter treated here is described by using switching mode-equivalent circuits, together with its unique features. All the active power switches in the half-bridge arms and input DC bus lines can achieve ZCS turn-on and ZVS turn-off commutation transitions. The total turn-off switching losses of the power switches can be significantly reduced. As a result, high switching frequency IGBTs can actually be selected in the frequency range of 40[kHz] under the principle of soft-switching. The performance evaluations of the experimental setup are illustrated practically.

• 한국정보통신설비학회:학술대회논문집
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• 한국정보통신설비학회 2002년도 하계학술대회 및 세미나
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• pp.21-23
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• 2002

In millimeter wave applications, it is often necessary to use transitions between waveguide and planar circuits. Finline structures can be used effectively to this purpose. In multilayered case, it is necessary to analyze the structure with numerical method such as spectral domain immittance method. The design procedure uses tile cutoff frequency for each taper width. The dispersion data in a single layer are compared with those in literature. The performance of the designed finline taper is verified with the FEM simulation using HFSS.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2012년도 추계학술대회
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• pp.570-572
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• 2012

In this paper, a three-dimensional (3-D) low-loss and wide-band BPF based on low-temperature co-fired ceramic (LTCC) has been presented for mm-wave wireless communication applications. The proposed BPF is designed in a 6-layer LTCC substrate. The double patch resonators are fully integrated into the LTCC dielectrics and vertical via and planar CPW transitions are designed for interconnection between embedded resonators and in/output ports and MMICs, respectively. The designed BPF was fabricated in a 6-layer LTCC dielectric. The fabricated BPF shows a centre frequency (fc) of 53.23 GHz and a 3dB bandwidth of 14.01 % from 49.5 to 56.9 GHz (7.46 GHz). An insertion loss of -1.56 dB at fc and return losses below -10 dB are achieved. Its whole size is $4.7{\times}1.7{\times}0.684mm^3$.

• Journal of Electrical Engineering and Technology
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• 제2권1호
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• pp.89-97
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• 2007

This paper presents a new circuit topology of active edge resonant snubbers assisted half-bridge soft switching PWM inverter type DC-DC high power converter for DC bus feeding power plants. The proposed DC-DC power converter is composed of a typical voltage source-fed half-bridge high frequency PWM inverter with a high frequency planar transformer link in addition to input DC busline side power semiconductor switching devices for PWM control scheme and parallel capacitive lossless snubbers. The operating principle of the new DC-DC converter treated here is described by using switching mode equivalent circuits, together with its unique features. All the active power switches in the half-bridge arms and input DC buslines can achieve ZCS turn-on and ZVS turn-off commutation transitions. The total turn-off switching losses of the power switches can be significantly reduced. As a result, a high switching frequency IGBTs can be actually selected in the frequency range of 60 kHz under the principle of soft switching. The performance evaluations of the experimental setup are illustrated practically. The effectiveness of this new converter topology is proved for such low voltage and large current DC-DC power supplies as DC bus feeding from a practical point of view.

• 한국전자파학회논문지
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• 제21권9호
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• pp.1037-1044
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• 2010

본 논문에서는 한 쌍의 동위상 및 역위상 전이 구조로 이루어진 초광대역 위상 역전 전이 구조를 이용하여 소형화된 크기와 광대역 특성을 갖는 새로운 구조의 링 하이브리드를 제안하고, 그 응용의 예로서, 단일 평형 주파수 체배기를 구현한 예를 보여주고 있다. 제안된 링 하이브리드는 기존의 링 하이브리드 대비 65 % 축소된 크기를 가지며, $\sum$ 단자와 $\Delta$ 단자에서 각각 92.5 %와 81.3 %의 대역폭을 갖는다. 또한, 동작 주파수 대역에서 균일한 크기 및 위상의 평형도를 가지므로, 다양한 평형 소자에 응용될 수 있다. 새로운 구조의 링 하이브리드를 이용하여 제작된 주파수 체배기는 회로 시뮬레이션 결과와 유사한 특성을 가지며, 15 dBm의 입력 신호를 인가 할 경우 4~12 GHz 대역에서 평균 10.5 dB 변환 손실과 28 dB 이상의 입력 주파수 신호 억압도를 나타낸다.