• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2005년도 추계종합학술대회
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• pp.163-166
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• 2005

Multilayer LTCC technology enables RF modules to be reduced dramatically by taking advantage of the three dimension flexibility. Compared to a conventional two dimensional PCB, LTCC allows higher density, reduced size, and lower cost. In this research, BPF based on LTCC for 900MHz ZigBee application was implemented which can replace SAW filter with using the material of the Dupont9599's dielectric constant 7.8. And distributed baud pass filter for 900MHz ZigBee system applications is presented. Using resonator stripline and capacitance, 2nd order band pass filter was designed. Adjusting resonator's length and capacitance is easy to tune at accurate center frequency by shifting band because ZigBee system is using narrow bandwidth, $902MHz^{\sim}928MHz$. Also resonator has no limitation in space, so reducing size is possibile. Designed filter had I.L. 2.8dB at 915MHz and attenuation at 815MHz, 1015MHz was 16dB, 15dB, respectively. Therefore, the sharpe cut-off and good insertion loss for ZigBee system application.

• 방사선산업학회지
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• 제9권3호
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• pp.137-141
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• 2015

A single-shot dual-energy x-ray imaging technique has been developed using a sandwich detector by stacking two detectors, in which the front and rear detectors respectively produce relatively lower and higher x-ray energy images. Each detector layer is composed of a phosphor screen coupled with a photodiode array. The front detector layer employs a thinner phosphor screen, whereas the rear detector layer employs a thicker phosphor screen considering the quantum efficiency for x-ray photons with higher energies. We have applied the proposed method into the inspection of printed circuit boards, and obtained dual-energy images with background clutter suppressed. In addition, the single-shot dual-energy method provides sharper-edge images than the conventional radiography because of the unsharp masking effect resulting from the use of different thickness phosphors between the two detector layers. It is promising to use the single-shot dual-energy x-ray imaging for high-resolution nondestructive testing. For the reliable use of the developed method, however, more quantitative analysis is further required in comparisons with the conventional method for various types of printed circuit boards.