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Guidance Properties of Metal Wire Waveguide by Terahertz Pulse Propagation
지영빈,전태인,Eui Su Lee,Jin Seok Jang,Kang-Yong Kwang,Min Hwan Kwak 한국물리학회 2007 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.50 No.I
We report an experimental and theoretical study of the guidance properties on the surface of copper and stainless steel wires in the terahertz frequency range. Instead of using quasioptic coupling, optoelectronically generated THz pulses by silicon on sapphire (SOS) photoconductive dipole antenna were directly launched onto a 0.5-mm-diameter copper and stainless steel wire. After a 71-cm propagation of the curved wires, the guided THz pulses were directly detected at the end of the wires using another SOS photoconductive dipole antenna. The guided THz pulses for the two wires have very high attenuation and group velocity dispersion. Because of the stainless steel wire's minimal conductivity, it has better guidance property compared with that of copper wire. To explain the results, we theoretically calculated the field distribution for the two cases. Also, we suggest the use of the copper wire for the straight region and stainless steel wire for the curved region to ensure minimal THz attenuation.
Coupling Properties of a Conical Tungsten-Wire Waveguide in the Terahertz Frequency Range
전태인,지영빈,이의수,장진석,김상훈,곽민환,강성범,강광용 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.53 No.2
The coupling properties of a conical tungsten-wire waveguide in the terahertz (THz) frequency range were investigated through theoretical simulations and experiments. As the tip of a conical wire has a smaller diameter than that of a cylindrical wire, it has a greater THz field density than the latter. After the THz pulse had been coupled to the receiver (Rx) by using a 1-μm-diameter conical wire tip, the detected THz pulse increased 5.3 times compared with the pulse when a 500-μm-diameter cylindrical wire tip was used. This result coincides with that of the theoretical simulations, in which a high-frequency structure simulator (HFSS) was used, when likewise conrmed that coupling a conical wire to Rx was about 1,000 times more sensitive than wire-to-wire coupling.
전태인,지영빈,Jeon, Tae-In,Ji, Young-Bin 한국광학회 2006 한국광학회지 Vol.17 No.3
전기전도도가 높은 구리선 도파로에 THz 전자기파의 결합은 THz 유선방식의 전파에 있어 테라파의 크기 및 주파수 특성을 결정짓는 중요한 요인 중의 하나이다. 본 연구에서는 직경 $480{\mu}m$, 길이 23 cm의 구리선 도파로에 테라파를 전파시켜 1 THz 주파수 범위를 가진 THz 펄스를 측정하였다. 도파로와 transmitter chip 또는 receiver chip 사이의 공극 간격을 최대 $275{\mu}m$까지 확대하여 송신부와 수신부의 결합 특성을 접촉상태와 비교 분석하였다. 실험결과 송신부의 결합민감도가 수신부보다 약 3배 이상 높게 나타났으며 수신부에서 도파로와 receiver사이의 공극을 통하여 테라파가 공기 중으로 전파됨을 알 수 있었다. 또한 구리선 도파로에 pin hole를 위치시켜 pin hole의 직경에 따른 테라파의 변화를 연구하였으며 대부분의 THz field는 구리선 표면에 분포됨을 확인할 수 있었다. The coupling between copper wire and a THz electromagnetic wave is one of the important factors to build up the magnitude and spectrum of a THz wave. We measured a I THz spectrum range THz pulse into a $480{\mu}m$ diameter and 23cm long copper wire waveguide. We measured THz pulses up to $275{\mu}m$ air gap between the end of the copper wire and transmitter or receiver chips. The coupling sensitivity of the transmitter is 3 times bigger than that of the receiver. The THz pulses propagated to air by the end of the receiver-side copper wire tip acting as a transmitter antenna. We confirmed that the THz field concentrates near the copper wire surface by opening the pin hole to the copper wire waveguide.
롤투롤 스퍼터링 증착을 통한 납(Pb) 대체용 방사선 차폐필름 개발
김성헌,변정섭,지영빈 한국방사선학회 2023 한국방사선학회 논문지 Vol.17 No.3
Lead(Pb), which is currently mainly used for shielding purposes in the medical radiation, has excellent radiation shielding functions, but is continuously exposed to radiation directly or indirectly due to the harmfulness of lead itself to the human body and the inconvenience caused by its heavy weight. Research on shielding materials that are human-friendly, lightweight, and convenient to use that can block risks and replace lead is continuously being conducted. In this study, based on the commonly used polyethylene terephthalate (PET) film and the fabric material used in actual radiation protective clothing, a multi-layer thin film was realized through sputtering and vacuum deposition of bismuth, tungsten, and tin, which are metal materials that can shield radiation. Thus, a shielding film was produced and its applicability as a radiation shielding material was evaluated. The radiation shielding film was manufactured by establishing the optimized conditions for each shielding material while controlling the applied voltage, roll driving speed, and gas supply amount to manufacture the shielding film. The adhesion between the parent material and the shielding metal thin film was confirmed by Cross-cut 100/100, and the stability of the thin film was confirmed through a hot water test for 1 hour to measure the change of the thin film over time. The shielding performance of the finally realized shielding film was measured by the Korea association for radiation application (KARA), and the test conditions (inverse wide beam, tube voltage 50 kV, half layer 1.828 mmAl) were set to obtain an attenuation ratio of 16.4 (initial value 0.300 mGy/s, measured value 0.018 mGy/s) and damping ratio 4.31 (initial value 0.300 mGy/s, measured value 0.069 mGy/s) were obtained. by securing process efficiency for future commercialization, light and shielding films and fabrics were used to lay the foundation for the application of films to radiation protective clothing or construction materials with shielding functions. 현재 의료방사선 분야에서 차폐를 목적으로 주로 사용되고 있는 납(Pb)소재는 방사선 차폐 기능은 뛰어나지만 납 자체가 가지고 있는 인체 유해성과 무거운 무게에 의한 불편함 때문에 지속적으로 직, 간접적으로 방사선 피폭 위험을 차단함과 동시에 납 소재를 대체할 수 있는 인체 친화적인이며 가벼우면서 사용편의성을 가진 차폐소재의 연구는 지속적으로 진행되어지고 있다. 본 연구에서는 일반적으로 사용되는 PET (polyethylene terephthalate) 필름과 실제 방사선 방호복 사용되는 원단소재를 기재로 하여 방사선을 차폐할 수 있는 금속물질인 비스무트, 텅스텐, 주석을 스퍼터링 진공증착 방식을 통한 다층박막을 구현하여 차페 필름을 제작하여 방사선 차폐소재로의 적용가능성을 평가하였다. 차폐필름을 제작하기 위한 인가전압, 롤 구동속력, 가스공급량을 제어하면서 차폐물질별 최적화된 조건을 확립하여 방사선 차폐필름 제작하였다. 모재와 차폐금속박막간 밀착력 확인은 Cross-cut 100/100으로 확인하였고 시간에 따른 박막의 변화를 측정하기 위해 내열탕 테스트 1시간을 통하여 박막의 안정성을 확인하였다. 최종적으로 구현된 차폐필름의 차폐성능은 한국방사선진흥협회를 통한 실제 방사선 차폐성능을 측정한 결과 시험조건(역넓은 빔, 관전압 50 kV, 반가층 1.828 mmAl)을 설정하여 감쇠비 16.4 (초기값 0.300 mGy/s, 측정값 0.018 mGy/s)와 감쇠비 4.31 (초기값 0.300 mGy/s, 측정값 0.069 mGy/s)의 결과를 얻었다. 추후 제품화를 위한 공정효율성을 확보하여 가벼우면서 차폐성능을 보유한 필름 및 원단을 활용하여 방사선 방호복이나 차폐기능을 가진 건축자재로의 필름적용을 위한 초석을 마련하였다.