• 한국전자파학회논문지
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• 제21권4호
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• pp.340-351
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• 2010

전기적인 장치를 기반으로 한 테라헤르츠 송신기(Terahertz Transmitter: Tx)를 이용하여 0.34 THz의 전자기파를 발생시키는 소형 CW sub-THz 이미징 시스템을 제시하였다. Tx에 의해 발생된 0.34 THz의 전자기파는 테라 헤르츠 수신기(Terahertz Receiver: Rx)를 이용하여 샘플의 진폭(magnitude)과 위상(phase) 정보를 각각 측정하였다. 이 논문에서는 보다 좋은 이미지 해상도를 얻기 위하여 데이터 수집 시 이미지의 분해능(resolution)에 영향을 미치는 주사 스테이지(scanning stage)의 시간 지연과 스텝 거리를 변수로 두어 다양한 샘플들을 주사하여 그 결과를 측정, 비교하였다. 또한 플라스틱, 종이, 나무 등 다양한 샘플들의 이미징 측정을 통해 테라헤르츠 파의 응용 가능성을 확인하였다.

• 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.

• 비파괴검사학회지
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• 제30권4호
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• pp.352-358
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• 2010

전기적인 장치를 기반으로 한 테라헤르츠 송신기(terahertz transmitter; Tx)를 이용하여 0.34 THz의 전자기파를 발생시키는 소형 CW sub-THz 이미징 시스템을 제시하였다. Tx에 의해 발생된 0.34 THz의 전자기파를 point by point 스캔방식으로 샘플에 투과시켰고, 여기서 얻어진 데이터는 테라헤르츠 수신기(terahertz receiver; Rx)를 이용하여 진폭(magnitude)과 위상(phase) 정보로 측정한 후 이를 영상화하였다. 이 논문에서는 보다 좋은 이미지 해상도를 얻기 위하여 데이터 수집 시 이미지의 분해능(resolution)에 영향을 미치는 주사 스테이지(scanning stage)의 시간지연과 스텝거리를 변수로 두어 다양한 샘플들을 주사하여 그 결과를 측정, 비교하였다. 또한 플라스틱, 종이, 나무 등 다양한 샘플들의 이미징 측정을 통해 테라헤르츠 파의 응용 가능성을 확인하였다.

• 한국전자파학회논문지
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• 제29권2호
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• pp.77-82
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• 2018

테라헤르츠 영역에서 MIM(Metal - Insulator - Metal) 도파관이 주기적으로 배열되어 있는 경우, 도파관 두께의 변화에 따른 전자파의 투과 특성은 널리 연구되지 않았다. 본 논문에서는 금속이 금으로 구성된 주기 구조의 경우 MIM 도파관에 수직으로 입사하는 수평 편파에 의한 전자파의 투과 특성을 다양한 테라헤르츠 주파수 영역에서 확인하고, 그 결과를 분석하고자 한다. 또한 완전 도체의 경우와 비교해 봄으로써 그 차이점을 확인한다.

• 한국전자파학회지:전자파기술
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• 제23권5호
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• pp.25-35
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• 2012

• 대한방사성의약품학회지
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• 제6권2호
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• pp.102-115
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• 2020

In the state of Positronium (Ps), which is an unstable material created by the temporary combination of electrons and positrons, the imaging technology through photo-conversion methodology is emerging as a new research theme under resonance conditions through terahertz electromagnetic waves. Normally, Positronium can be observed in the positron emission computed tomography (PET) process when an unstable, separate state that remains after the pair annihilation of an electron and a positron remains. In this study, terahertz (THz) waves and Cherenkov radiation (CR) are generated using the principle of ponderomotive force in the plasma wake-field acceleration, and electrons and positrons are simultaneously generated by using a relativistic electron beam without using a PET device. We confirm the possibility of Positronium photoconversion technology in terahertz electromagnetic resonance conditions through experimental studies that generate an unstable state. Here, a relativistic electron beam (REB) energy of 0.5 MeV (γ=2) was used, and the terahertz wave frequencies is G-band. Meanwhile, a THz wave mode converting three-stepped axicon lens was used to apply the photoconversion technology. Through this, light emission in the form of a luminescence-converted Bessel beam can be verified. In the future, it can be used complementarily with PET in nuclear medicine in the field of medical imaging.

• Journal of electromagnetic engineering and science
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• 제11권1호
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• pp.42-50
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• 2011

One of the important applications of THz time-domain spectroscopy (TDS) is the detection of explosive materials through identification of vibrational fingerprint spectra. Most recent THz spectroscopic measurements have been made using pellet samples, where disorder effects contribute to line broadening, which results in the merging of individual resonances into relatively broad absorption features. To address this issue, we used the technique of parallel plate waveguide (PPWG) THz-TDS to achieve sensitive characterization of three explosive materials: TNT, RDX, and HMX. The measurement method for PPWG THz-TDS used well-established ultrafast optoelectronic techniques to generate and detect sub-picosecond THz pulses. All materials were characterized as powder layers in 112 ${\mu}m$ gaps in metal PPWG. To illustrate the PPWG THz-TDS method, we described our measurement by comparing the vibrational spectra of the materials, TNT, RDX, and HMX, applied as thin powder layers to a PPWG, or in conventional sample cell form, where all materials were placed in Teflon sample cells. The thin layer mass was estimated to be about 700 ${\mu}g$, whereas the mass in the sample cell was ~100 mg. In a laboratory environment, the absorption coefficient of an explosive material is essentially based on the mass of the material, which is given as: ${\alpha}({\omega})=[ln(I_R({\omega})/I_S({\omega}))]m$. In this paper, we show spectra of 3 different explosives from 0.2 to 2.4 THz measured using the PPWG THz-TDS.

• 전자통신동향분석
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• 제36권3호
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• pp.97-105
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• 2021

The terahertz wave (THz wave) is a band between infrared and microwaves and is defined as an electromagnetic wave having a frequency of 0.1 to 10 THz band. THz waves have the property of transmitting nonpolar materials, which the visible light cannot be transmitted, such as ceramics, plastics, and paper; and the photon energy is low, such as several meV. For this reason, non-destructive testing equipment based on THz imaging technology can be applied to the industrial field. Recently, THz imaging technology was applied in wide industrial fields, such as automobiles, batteries, food, medical, and security, and being actively studied. In this paper, we describe the research trends of terahertz imaging technology and experimental results. Furthermore, we summarize the recent commercialized terahertz camera. Finally, we present the research results in the field of the human security scanner system.

• Journal of electromagnetic engineering and science
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• 제17권4호
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• pp.202-207
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• 2017

This paper presents the performance of a planar, low-profile, and wide-gain-bandwidth leaky-wave slit antenna in different thickness values of high-permittivity gallium arsenide substrates at terahertz frequencies. The proposed antenna designs consisted of a periodic array of $5{\times}5$ metallic square patches and a planar feeding structure. The patch array was printed on the top side of the substrate, and the feeding structure, which is an open-ended leaky-wave slot line, was etched on the bottom side of the substrate. The antenna performed as a Fabry-Perot cavity antenna at high thickness levels ($H=160{\mu}m$ and $H=80{\mu}m$), thus exhibiting high gain but a narrow gain bandwidth. At low thickness levels ($H=40{\mu}m$ and $H=20{\mu}m$), it performed as a metasurface antenna and showed wide-gain-bandwidth characteristics with a low gain value. Aside from the advantage of achieving useful characteristics for different antennas by just changing the substrate thickness, the proposed antenna design exhibited a low profile, easy integration into circuit boards, and excellent low-cost mass production suitability.

• 한국광학회지
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• 제13권5호
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• pp.430-434
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• 2002

$12{\mu}{\textrm}{m}$ 길이, $5{\mu}{\textrm}{m}$ gap의 dipole 안테나에 입사되는 펨토초 레이저의 위치에 따른 테라헤르트 전자기 펄스의 크기를 관찰하였다. 비록 11volt의 작은 전압을 인가 시켰음에도 불구하고 테라헤르츠 전자기 펄스가 최대 4.7nA의 전류로 발생되었는데 이는 dipole 안테나 구조가 아닌 두 전송라인(transmission line)의 간격이 $300{\mu}{\textrm}{m}$ 떨어진 구조의 송신기(transmitter chip)에 비해 6배 작은 전압을 인가하여 3.4배 더 큰 전류가 발생됨을 알 수 있었다. 또한 팸토초 레이저로 여기 되는 dipole 안테나 구조의 송신기에 구형 교류전압을 최소 0.11volt에서 최대 10volt까지 변화시켜 테라헤르트 전자기 펄스의 최대값 크기에 따른 이진신호를 발생시켰다.