• Electronics and Telecommunications Trends
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• v.34 no.5
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• pp.26-35
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• 2019

Modern imaging technologies utilizing electromagnetic waves are indispensable in our daily lives. Applications, such as television and smartphone screens, radar imaging for weather forecast, and medical imaging, can be attributed to technology developments in various electromagnetic regions. Terahertz (THz) waves, electromagnetic (EM) waves located between far infrared and microwave regions, had left unexplored EM waves. Recent advances in technology have led to various two-dimensional and three-dimensional THz imaging techniques. In this article, we explain THz imaging techniques as well as the experimental results from our laboratory. Additionally, we introduce commercial THz cameras developed worldwide. Finally, we present the applications of THz imaging techniques.

• Electronics and Telecommunications Trends
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• v.32 no.3
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• pp.56-67
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• 2017

오랫동안 미개척 주파수 대역이었던 테라헤르츠 대역은 소자 및 시스템 기술 연구성과의 축적과 기술 성숙 과정을 거쳐, 최근 다수의 상용화 시스템이 출시되는 등 산업 분야에의 응용이 확산되었다. 특히, 투과 이미징이 가능한 테라헤르츠 이미징 시스템은 산업 분야에서 비접촉 비파괴 품질검사 분야 등에 많은 응용이 기대되고 있다. 이밖에 분광 기술에 기반을 둔 막 두께 측정 시스템, 초고속 통신 시스템 등도 향후 중요한 테라헤르츠 기술 응용 분야로 여겨지고 있다. 본고에서는 테라헤르츠 응용 기술에 관한 최근의 연구 동향을 간략히 살펴보고, 한국전자통신연구원 전파위성연구본부 테라헤르츠 창의원천연구실에서 주력해 온 포토닉스 기반 테라헤르츠 소자 및 시스템에 관해 상세히 소개한다.

• Electronics and Telecommunications Trends
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• v.36 no.3
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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 the Korean Society for Nondestructive Testing
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• v.30 no.4
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• pp.352-358
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• 2010

This paper presented compact CW sub-THz imaging system using the terahertz transmitter(Tx) that generating 0.34 THz electromagnetic wave on based electronic device. Using 0.34 THz electromagnetic wave generated by Tx, we transmitted to sample by point by point scan method and measured transmitting terahertz wave magnitude and phase information respectively with terahertz receiver(Rx) based on sub harmonic mixer. This paper measured and compared images of several samples to obtain better imaging results by changing time delay and step distance of scanning stage which affect image resolution. Also, through the imaging measurement of various samples, we were able to assure possibility of application of terahertz wave.

• Conservation Science in Museum
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• v.29
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• pp.111-132
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• 2023

Terahertz radiation cannot pass through metal and therefore reflect and return most signals. Utilizing this property, this study analyzed information on paintings to verify the usage of metal materials on paintings and the scope of their application. First, the study tested specimens of metal-based pigments and synthetic pearl pigments with metallic colors and textures in order to compare basic characteristics of terahertz images, such as signal severance caused by metallic substances, traits reflected in cross-section images, and high degree of reflection. Subsequently, based on the collected information, the study diagnosed various types of paintings including Korean traditional paintings and oil paintings using the terahertz imaging technique to confirm the usage of metal-based pigments in the inner layers of paintings and their scope of application. The terahertz imaging technique could has the potential to provide scientific evidence for previously-undiscovered information and art-historical records about various types of paintings that used metalbased pigments, thereby rendering significant utility for the conservation and authentication of paintings.

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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• v.26 no.1
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• pp.65-67
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• 2015

주요 미래 전파자원으로 주목 받아온 테라헤르츠 주파수 대역을 이용한 시스템 개발은 최근 향상된 성능과 낮은 비용으로 제공되는 능동 전자소자의 대두로 현실화 가능성이 급속히 증가하고 있다. 인체에 무해하며, 향상된 정밀도를 제공하는 테라헤르츠 전자파의 특성을 활용한 은닉 무기 탐지 시스템을 낮은 제작비용에 이동이 용이한 소형 구조로 구현하는 연구 과제를 2012년 이후 고려대에서 수행 중에 있다.

• Electronics and Telecommunications Trends
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• v.24 no.5
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• pp.119-132
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• 2009

새로운 전파자원으로서 초고속 무선통신뿐만 아니라 분광, 센싱, 이미징 등 여러 분야에서 다양한 응용이 기대되는 연속 밀리미터파와 테라헤르츠-파에 대한 발생 및 응용기술을 논하였다. 밀리미터파의 경우 전자소자를 이용한 방법을 주로 사용하지만, 테라헤르츠-파는 전자 및 광기술을 모두 사용하여 발생시킬 수 있다. 본 글에서는 광학적 방식을 이용한 연속 밀리미터/테라헤르츠-파의 발생기술과 이를 이용한 응용기술에 대하여 논하였다. 최근 고출력 PD의 기술발전에 따라 광학적 발생방식의 밀리미터/테라헤르츠-파를 이용한 CW 분광 측정이 유용할 것으로 보인다. 현 단계에서 1THz에서의 최대 가용 출력은 약 $10{\mu}W$ 정도이나, 포화전류와 열 관리 문제를 해결하고 PD 성능의 개선을 함으로써, 단일 소자에서 1THz에 대한 최대 가용출력이 $100{\mu}W$ 수준이 될 것으로 기대된다. 연속 밀리미터/테라헤르츠-파 분광법은 더욱 정밀하고, 다양하며 경제적인 분광 시스템 기술에 크게 기여할 것으로 전망된다.

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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• v.26 no.5
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• pp.51-57
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• 2015

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.4
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• pp.340-351
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• 2010

This paper presented compact CW sub-THz imaging system using the terahertz transmitter(Tx) that generates 0.34 THz electromagnetic wave based on electronic device. Using 0.34 THz electromagnetic wave generated by Tx, we measured transmitting terahertz wave magnitude and phase information respectively with terahertz receiver(Rx) based on sub harmonic mixer. This paper measured and compared images of several samples to obtain better imaging results by changing time delay and step distance of scanning stage which affect image resolution. Also, through the imaging measurement of various samples, we were able to assure possibility of application of terahertz wave.

• Journal of Conservation Science
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• v.32 no.2
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• pp.235-247
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• 2016

Conventional imaging techniques such as ultraviolet, infrared, and X-ray are used mainly to diagnose the damaged parts of the painted cultural assets in Korea. These techniques, however, have limits in diagnosing damages of interlayer parts. We have performed and extensive study on the applicability of Terahertz(THz) analysis technique, introduced recently to this field of study on cultural properties in Korea, to diagnose painted cultural assets. The specimens, produced to imitate the damage types of Korean painted properties, were analyzed over their painting, supporting, and backing layers by terahertz pulse imaging technique. The analyzed results provided information about the cracks, the separated areas, and the separated distances between layers on the specimens. Our research, then, was extended to real painted cultural remains, Birojana Sam-shin Gwebul-do at Bongseon Temple in Namyang-ju, Korea National Treasure Number 1792, through which we have obtained 3D information about the extent and pattern of damages to the asset. These results demonstrate that terahertz 3D imaging technique has the capability of noncontact 3D diagnosis on painted cultural properties.