A5043663350- Terahertz technology and applications
- Photonic and Optical Devices
- Ferroelectric and Piezoelectric Materials
- Microwave Dielectric Ceramics Synthesis
- Acoustic Wave Resonator Technologies
- Spectroscopy and Laser Applications
- Microwave Engineering and Waveguides
- Superconducting and THz Device Technology
- Metamaterials and Metasurfaces Applications
- Advanced Antenna and Metasurface Technologies
- Antenna Design and Analysis
- Semiconductor Lasers and Optical Devices
- Millimeter-Wave Propagation and Modeling
- Image Enhancement Techniques
- Semiconductor Quantum Structures and Devices
- Radio Wave Propagation Studies
- Image and Signal Denoising Methods
- Multiferroics and related materials
- Advanced Image Processing Techniques
- Ferroelectric and Negative Capacitance Devices
- Advanced Fiber Laser Technologies
- Generative Adversarial Networks and Image Synthesis
- Advanced Memory and Neural Computing
- Surface Roughness and Optical Measurements
- Remote Sensing and LiDAR Applications
Sahmyook University
2015-2025
Samsung (South Korea)
2015
Korea Institute of Science and Technology
2015
Electronics and Telecommunications Research Institute
2004-2014
Changwon National University
2014
Korea Advanced Institute of Science and Technology
2010
Massey University
2005
This work reviews the results of NTIRE 2023 Challenge on Image Shadow Removal. The described set solutions were proposed for a novel dataset, which captures wide range object-light interactions. It consists 1200 roughly pixel aligned pairs real shadow free and affected images, captured in controlled environment. data was white-box setup, using professional equipment lights acquisition sensors. challenge had number 144 participants registered, out 19 teams compared final ranking. extend...
An electrically controllable square-loop metamaterial based on vanadium dioxide (VO2) thin film was proposed in the terahertz frequency regime. The shaped adopted to perform roles not only as a resonator but also micro-heater for electrical control of VO2. A dual-resonant structure designed realize band-pass characteristics desired band. measured Q-factors basic and scaled-down metamaterials fabricated VO2 films were 2.22 1.61 at center frequencies 0.44 1.14 THz passbands, respectively....
The effects of anisotropic dielectric properties ferroelectric Ba1−xSrxTiO3 (BST) films on the characteristics interdigital (IDT) capacitors have been studied in microwave regions at room temperature. Ferroelectric BST with (001), (011), and (111) orientation were epitaxially grown MgO substrates, respectively, by pulsed laser deposition method. engineered investigated using capacitors. calculated constant tunability 40 V dc bias variation quality factor values for IDT based oriented 9 GHz...
We demonstrate a tunable continuous-wave (CW) terahertz (THz) homodyne system with novel detuned dual-mode laser diode (DML) and low-temperature-grown (LTG) InGaAs photomixers. The optical beat source the DML showed frequency tuning range of 0.26 to over 1.07 THz. Log-spiral antenna integrated LTG photomixers are used as THz wave generators detectors. CW radiation was continuously tuned 1 Our results clearly show feasibility compact fast scanning spectrometer consisting fiber-coupled...
In this paper, we propose an asymmetric split-loop resonator with outer square loop (ASLR-OSL) based on vanadium dioxide (VO2) which can actively control the transmission characteristics of a terahertz wave while maintaining high quality factor (ASLR) by adding loop. The proposed ASLR-OSL demonstrated similar to those ASLR, and were successfully controlled directly applying bias voltage. These results show simple method for imposing active properties common metamaterial having structure.
Compositionally graded (Bax, Sr1−x)TiO3 (BST) thin films were deposited on MgO substrates by pulsed laser ablation. The microwave properties of the BST investigated at frequencies with coplanar waveguide (CPW) meander-line phase shifters as a function direction composition gradient respect to substrate room temperature. CPW using BaTiO3(BT)→SrTiO3(ST) and ST→BT exhibited differential shift 73° 22° 10 GHz dc bias voltage 150 V, respectively. figure merit was 14.6 deg/dB for BT→ST film, film....
Abstract The construction site is one of the most dangerous industries because number occupational injuries and fatalities significantly higher compared to other industries. Proper use personal protective equipment (PPE) by workers can reduce risk fatalities. However, for a variety reasons, tend not wear their PPEs properly. To address these issues, we propose vision-based framework monitoring wearing PPE. developed based on real-time pixel-level detect model YOLACT, which employs...
A simple thickness measurement method based on the coherent homodyne CW THz system was demonstrated; it does not require precise control of frequencies beat source, and only accurate scanning optical delay line is needed. Three are sufficient for measuring a sample without considering modulo 2π ambiguity. novel compact 1.55 μm λ/4 phase-shifted dual-mode laser (DML) developed as an source system. The accurately estimated from measurements using proposed method. Our results clearly show...
We propose a compact fiber-pigtailed InGaAs photoconductive antenna (FPP) module having an effective heat-dissipation solution as well volume of less than 0.7 cc. The the FPP modules when using heat-conductive printed circuit board (PCB) and aluminium nitride (AlN) submount, without any cooling systems, improve by 40% 85%, respectively, compared with chip on conventional PCB. AlN submount is superior to those previously reported solution. Terahertz time-domain spectroscopy (THz-TDS)...
The successful demonstration of an optical fiber-coupled terahertz time–domain spectroscopy (THz-TDS) system is described in this study. output power the emitter with two band rejection filters was 132 nW, which improvement 70% over without any filters. This due to suppression modulated signal that reverse-generated when alternating current bias exceeding a certain threshold applied emitter. Under optimal alignment conditions, detector THz-TDS clearly measured water vapor dips free space.
A widely tunable dual mode laser diode with a single cavity structure is demonstrated. This novel device consists of distributed feedback (DFB) and Bragg reflector (DBR). Micro-heaters are integrated on the top each section for continuous independent wavelength tuning mode. By using gain medium in DFB section, an effective common optical modes realized. The shows wide tunability beat frequency, from 0.48 THz to over 2.36 THz. Continuous wave radiation also successfully generated...
We report a high-speed (~2 kHz) dynamic multiplexed fiber Bragg grating (FBG) sensor interrogation using wavelength-swept laser (WSL) with polygon-scanner-based wavelength filter. The scanning frequency of the WSL is 18 kHz, and 10 dB bandwidth more than 90 nm around center 1,540 nm. output from coupled into FBG array, which consists five FBGs. reflected wavelengths FBGs are 1,532.02 nm, 1,537.84 1,543.48 1,547.98 1,553.06 respectively. A periodic strain ranging 500 Hz to 2 kHz applied one...
Abstract A Ta/TaO x /Pt stacked capacitor-like device for resistive switching was fabricated and examined. The tested demonstrated stable characteristics including uniform distribution of operational parameters, highly promising endurance retention properties. To reveal the mechanism device, micro structure analysis using high-resolution transmission electron microscope (HR-TEM) performed. From observation results, two different phases Ta-metal clusters cubic α-Ta tetragonal β-Ta were...
Electrical endurance characteristic of resistive switching MnOx thin film was investigated associated with various oxygen concentrations. From experimental results top electrode changing on the examined devices and concentration during post-deposition annealing process, it revealed that electrical can be significantly improved by possessing high “non-lattice oxygen” in minimizing out-diffusion switching. Finally, a 250 nm-diameter via-hole structure device, composed TiN/MnOx/Pt, fabricated...
Terahertz (THz) waves are electromagnetic in the 0.1 to 10 THz frequency range, and imaging is utilized a range of applications, including security inspections, biomedical fields, non-destructive examination materials. However, images have low resolution due long wavelength waves. Therefore, improving current hot research topic. We propose novel network architecture called J-Net, which an improved version U-Net, achieve image super-resolution. It employs simple baseline blocks can extract...
Image inpainting and colorization are crucial tasks in image restoration, yet existing methods typically address them independently, limiting their applicability to complex real-world scenarios. Conventional techniques struggle with maintaining structural consistency arbitrarily masked regions, while models often assume fully restored grayscale inputs. To bridge this gap, we propose a unified framework that seamlessly integrates into single pipeline. Our approach leverages three...
Terahertz time-domain spectroscopy has been used to study the optical and dielectric properties of three chalcogenide glasses: Ge30As8Ga2Se60, Ge35Ga5Se60, Ge10As20S70. The absorption coefficients α(ν), complex refractive index n(ν), constants ɛ(ν) were measured in a frequency range from 0.3 THz 1.5 THz. real indices fitted using Sellmeier equation. results show that equation fits well with data throughout imply phonon modes glasses vary glass compositions. theory far-infrared amorphous...
We have developed a 1.3??m phase-shifted dual-mode laser diode (pDML) for tunable continuous-wave terahertz (CW THz) emitter. The mode beat frequency of the pDML is continuously tuned from 250 to 1480?GHz by introducing monolithically integrated micro-heaters and multiple sections an all-active structure. shows narrow spectral linewidth strong four-wave mixing signal throughout entire tuning range. By?combining InGaAs based photomixers, we successfully generated THz radiation, confirmed...
We propose a rapidly frequency-swept optical beat source for continuous wave (CW) THz generation using wavelength swept laser and fixed distributed feedback (DFB) laser. The range of the sweeping bandwidth is about 17.3 nm (2.16 THz), 1541.42-1558.72 nm. achieved side mode suppression ratio both wavelengths within full more than 45 dB. observe CW signals tunable sources fiber coupled measurement system to confirm feasibility our frequency as radiation source. output signal falls thermal...
Autonomous driving includes recognition, judgment, and control technologies, is implemented using sensors such as cameras, LiDAR, radar. However, recognition are exposed to the outside environment their performance may deteriorate because of presence substances that interfere with vision, dust, bird droppings, insects, during operation. Research on sensor cleaning technology solve this degradation has been limited. This study used various types concentrations blockage dryness demonstrate...