• 제목/요약/키워드: Terahertz-Ray

검색결과 17건 처리시간 0.028초

Terahertz Time Domain Spectroscopy, T-Ray Imaging and Wireless Data Transfer Technologies

  • Paek, Mun-Cheol;Kwak, Min-Hwan;Kang, Seung-Beom;Kim, Sung-Il;Ryu, Han-Cheol;Choi, Sang-Kuk;Jeong, Se-Young;Kang, Dae-Won;Jun, Dong-Suk;Kang, Kwang-Yong
    • Journal of electromagnetic engineering and science
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    • 제10권3호
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    • pp.158-165
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    • 2010
  • This study reviewed terahertz technologies of time domain spectroscopy, T-ray imaging, and high rate wireless data transfer. The main topics of the terahertz research area were investigation of materials and package modules for terahertz wave generation and detection, and setup of the terahertz system for time domain spectroscopy(TDS), T-ray imaging and sub-THz wireless communication. In addition to Poly-GaAs film as a photoconductive switching antenna material, a table-top scale for the THz-TDS/imaging system and terahertz continuous wave(CW) generation systems for sub-THz data transfer and narrow band T-ray imaging were designed. Dielectric properties of ferroelectric BSTO($Ba_xSr_{1-x}TiO_3$) films and chalcogenide glass systems were characterized with the THz-TDS system at the THz frequency range. Package modules for terahertz wave transmitter/receiver(Tx/Rx) photoconductive antenna were developed.

FRP 복합재료의 T-Ray 비파괴특성 평가 및 적용 (Evaluation and Application of T-Ray Nondestructive Characterization of FRP Composite Materials)

  • 임광희
    • 비파괴검사학회지
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    • 제30권5호
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    • pp.429-436
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    • 2010
  • 최근에는 T-ray(terahertz ray)를 이용한 비파괴기술이 새로운 분야로 주목을 받고 있다. 본 연구에서는 FRP 복합재료의 내재결함이나 레이업(lay-up) 특성을 검사 및 평가하기 위한 T-ray 시간영역 분광기(time-domain spectroscopy)를 활용하였으며 또한 이 T-ray 분광기의 일반적인 반사 및 투과모드를 이용하여 T-ray 이미지를 구현하였다. 특히, 2개의 톱날 인공결함이 내재한 GFRP 복합재의 평가방법을 제시하였다. CFRP 복합재료에 대해서는 T-ray 전파는 탄소섬유로 인해 진행 장해를 받는다. 이에 따라 T-ray의 전기장(E-field)의 방향과 탄소섬유 방향의 의존성을 분석하였다. 한편 인공결함인 알루미늄 테이프, 박리, 충격손상, 이물혼입 등을 T-ray를 이용하여 비파괴 검사 및 평가하였다. 이를 통해 FRP 복합재료의 T-ray비파괴평가의 적용 가능성 및 한계 등을 확인 할 수 있었다.

T-ray를 이용한 풍력터빈 브레이드 비파괴결함평가 (Nondestructive Evaluation of the Turbine Blade of Wind Energy By Using T-Ray)

  • 임광희;정종안;;이길성
    • 한국생산제조학회지
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    • 제21권1호
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    • pp.102-108
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    • 2012
  • A study of terahertz waves (T-ray) was made for the nondestructive evaluation of FRP (Fiber reinforced plastics) composite materials. The to-be-used systems were time domain spectroscopy (TDS) and continuous wave (CW). The composite materials investigated include both turbine blades of wind energy (non-conducting polymeric composites) and conducting carbon fiber composites. Terahertz signals in the TDS mode resembles that of ultrasound; however, unlike ultrasound, a terahertz pulse was not able to detect a material with conductivity. This was demonstrated in CFRP (Carbon fiber reinforced plastics) laminates. Refractive index (n) was defined as one of mechanical properties; so a method was solved in order solve the "n" in the material with the cut parts of the turbine blades of wind energy. The defects and anomalies investigated by terahertz radiation were foreign material inclusions and simulated disband. Especially, it is found that the T-ray went through the turbine blade with greater thickness (about 90mm).

테라헤르츠 신호를 이용한 영상의 글자 추출을 위한 화질 개선처리에 대한 연구 (A Study of Image Enhancement Processing for Letter Extraction of Image Using Terahertz Signal)

  • 김성윤;최현근;박인호;김영섭;이용환
    • 반도체디스플레이기술학회지
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    • 제16권3호
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    • pp.111-115
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    • 2017
  • Terahertz waves are superior to conventional X-ray or Magnetic Resonance Tomography(MRI), and the amount of information that can be transmitted is as large as thousands of times that conventional X-ray or MRI. In addition, Terahertz waves have great performance in analyzing an object which have some layered structure. By using this advantage, we can extract the letters of a page by analyzing information such as absorption amount and reflection amount by irradiating a closed book with pulses of various frequencies within gap of a terahertz wave. However, in the image of each page using the Terahertz wave might be obtained various kinds of noise and the different character occlusion region. So, to extract letters from the terahertz image, we must take the noise and occlusion region away. We have been working to enhancement the image quality in various ways, and keep on studying de-noising processing for enhancement about the image quality and high resolution. Finally, we also keep on studying about OCR(Optical Character Recognition) technology, which based on pattern matching technique, to read letters.

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테라헤르츠파를 이용한 풍력터빈 블레이드 NDE 탐상 평가기법 (NDE Inspecting Techniques for Wind Turbine Blades Using Terahertz Waves)

  • 임광희;김선규;정종안;조영태;우용득
    • 공학기술논문지
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    • 제11권4호
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    • pp.245-251
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    • 2018
  • Terahertz waves (T-ray) was extensively studied for the NDE (nondestructive evaluation) of characterization of trailing edges for a use of turbines composed with composite materials. The used NDE system were consisted of both CW(Continuous wave) and TDS (Time domain spectroscopy). The FRP composites were utilized for two kinds of both trailing edges of wind energy (non-conducting polymeric composites) and carbon fiber composites with conducting properties. The signals of T-ray in the TDS (Time domain spectroscopy) mode resembles almost that of ultrasound waves; however, a terahertz pulse could not penetrate a material with conductivity unlike ultrasound. Also, a method was suggested to obtain the "n" in the materials, which is called the refractive index (n). The data of refractive index (n) could be solved for the trailing edges. The trailing edges were scanned for characterization and inspection. C-scan and B-scan images were obtained and best optimal NDE techniques were suggested for complicated geometry samples by terahertz radiation. Especially, it is found that the defect image of T-ray corresponded with defect locations for the trailing edges of wind mill.

Characterization of Fiber Direction Influence in CFRP Composites Using Advanced NDE Techniques

  • Im, Kwang-Hee;Jang, Ju-Hwan;Back, Chong-Gui;Jeong, Ok-Su;Hsu, David K.
    • 한국생산제조학회지
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    • 제21권6호
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    • pp.1003-1007
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    • 2012
  • A nondestructive technique would be very useful. Advanced NDE T-ray (terahertz ray) techniques of technology and instrumentation has provided a probing field on the electromagnetic spectrum. However, the T-ray is limited in order to penetrate a conducting material to some degree. Here, the T-ray would not go through easily the CFRP composite laminates since carbon fibers are electrically conducting while the epoxy matrix is not. So, investigation of terahertz time domain spectroscopy (THz TDS) was made and reflection and transmission configurations were studied for a 48-ply thermoplastic PPS(poly-phenylene sulfide)-based CFRP solid laminate. It is found that the electrical conductivity of CFRP composites depends on the direction of unidirectional fibers.

광전도안테나에 의한 광대역테라헤르츠파의 발생특성 (Generation of Ultra-Wideband Terahertz Pulse by Photoconductive Antenna)

  • 진윤식;김근주;손채화;정순신;김지현;전석기
    • 대한전기학회논문지:전기물성ㆍ응용부문C
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    • 제54권6호
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    • pp.286-292
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    • 2005
  • Terahertz wave is a kind of electromagnetic radiation whose frequency lies in 0.1THz $\~$10THz range. In this paper, generation and detection characteristics of terahertz (THz) radiation by photoconductive antenna (PCA) method has been described. Using modern integrated circuit techniques, micron-sized dipole antenna has been fabricated on a low-temperature grown GaAs (LT-GaAs) wafer. A mode-locked Ti:Sapphire femtosecond laser beam is guided and focused onto photoconductive antennas (emitter and detector) to generate and measure THz pulses. Ultra-wide band THz radiation with frequencies between 0.1 THz and 3 THz was observed. Terahertz field amplitude variation with antenna bias voltage, pump laser power, pump laser wavelength and probe laser power was investigated. As a primary application example. a live clover leaf was imaged with the terahertz radiation.

테라헤르츠 영역에서의 BST 박막의 유전 특성 평가 (Terahertz dielectric characteristics of (Ba,Sr)$TiO_3$ thin films)

  • 조광환;강종윤;윤석진;이영백;맹인희;손주혁
    • 한국전기전자재료학회:학술대회논문집
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    • 한국전기전자재료학회 2007년도 추계학술대회 논문집
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    • pp.28-28
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    • 2007
  • Ferroelectric $(Ba_{0.5}Sr_{0.5})TiO_3$ (BST) thin films of thickness 500nm were deposited on $LaAlO_3$, (LAO) substrates by at $800^{\circ}C$. BST films were characterized for structure using X-ray diffraction (XRD). The surface morphology and thickness of BST the films were characterized by atomic force microscopy (AFM) and field emission scanning electron microscope (FESEM). We measured the dielectric properties at microwave frequencies (1~3 GHz) using a symmetrical stripline resonator with shorted ends and terahertz frequencies (0.2~2.5 THz) using a time-domain terahertz spectroscopy. The real and imaginary parts of the complex dielectric constant of the BST thin films on LAO substrates were in agreement with those previously reported.

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자유전자레이저의 개발현황과 전망 (Status and Prospect of Free Electron Lasers)

  • 이병철;정영욱;박성희;한상준
    • 한국진공학회지
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    • 제15권5호
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    • pp.435-450
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    • 2006
  • 자유전자레이저는 고에너지 전자빔의 운동에너지를 빛 에너지로 바꾸는 장치로서, 다른 어떤 종류의 광원으로도 제공할 수 없는 넓은 범위의 파장가변성과 우수한 분광특성을 갖고 있어, 기초연구에서부터 산업응용에 이르기까지 다양하게 활용될 수 있을 것으로 기대된다. 이 논문에서는 자유전자레이저의 원리와 특성, 요소기술을 소개하고, 최근 주목받고 있는 테라헤르츠파 자유전자레이저와 에너지 회수형 고출력 자유전자레이저에 대하여 자세하게 소개하였다.