A5001800527- Semiconductor Quantum Structures and Devices
- GaN-based semiconductor devices and materials
- Quantum optics and atomic interactions
- Laser-Matter Interactions and Applications
- Reservoir Engineering and Simulation Methods
- Acoustic Wave Resonator Technologies
- Advanced Fiber Laser Technologies
- Semiconductor Lasers and Optical Devices
- Photonic and Optical Devices
- Hydraulic Fracturing and Reservoir Analysis
- Methane Hydrates and Related Phenomena
- Radio Frequency Integrated Circuit Design
- Optical properties and cooling technologies in crystalline materials
- Thermography and Photoacoustic Techniques
- ZnO doping and properties
- Terahertz technology and applications
- Seismic Imaging and Inversion Techniques
- Ga2O3 and related materials
- Acoustic Wave Phenomena Research
- Quantum Information and Cryptography
- Thermal properties of materials
- Sugarcane Cultivation and Processing
- Thermal Radiation and Cooling Technologies
- Biofuel production and bioconversion
- Drilling and Well Engineering
Seoul National University
1997-2024
Institute of Crop Science
2013
Oklahoma State University
1994
We have studied the effects of an external electric field on photoluminescence spectra and carrier lifetimes in strained ${\mathrm{In}}_{x}{\mathrm{Ga}}_{1\ensuremath{-}x}\mathrm{N}/\mathrm{G}\mathrm{a}\mathrm{N}$ quantum wells embedded $p\ensuremath{-}i\ensuremath{-}n$ light-emitting diode (LED) structures. Two sample structures with $x=0.15$ for blue LED's 0.2 green been investigated, increasing reverse bias up to $\ensuremath{-}30 \mathrm{V}.$ From spectrum-resolved photoluminescence, we...
Femtosecond two beam, self-diffraction experiments are performed in ZnSe and ZnCdSe/ZnSe quantum wells. Degenerate wave mixing signals from the third to thirteenth order easily visible naked eye, implying that nonlinear effects this system may already be nonperturbative regime. Spectrally resolved data indicate nonlinearities originate entirely excitonic resonance. In addition, existence of four-wave bulk at negative time delay suggests exciton-exciton interaction plays an important role....
We show that large amplitude coherent acoustic phonon wave packets can be generated and detected in ${\mathrm{In}}_{x}{\mathrm{Ga}}_{1\ensuremath{-}x}\mathrm{N}∕\mathrm{GaN}$ epilayers heterostructures femtosecond pump-probe differential reflectivity experiments. The of the increases with increasing indium fraction $x$ unlike other oscillations, both period are strong functions laser probe energy. oscillation is substantially almost instantaneously reduced when packet reaches a GaN-sapphire...
Large amplitude time-domain oscillations are detected in InxGa1−xN/GaN structures via femtosecond differential reflectivity spectroscopy. The oscillation increases with increasing indium fraction and abruptly disappears at a critical time that depends on GaN thickness. We show spatially localized, coherent acoustic phonon wave packets generated the photoexcited carriers propagate into samples modulating reflectivity. Our results system strong built-in strain can be very effective source for...
We have studied the anti-Stokes photoluminescence (ASPL) of a type-II ${\mathrm{Al}}_{x}{\mathrm{Ga}}_{1\ensuremath{-}x}{\mathrm{A}\mathrm{s}\ensuremath{-}\mathrm{G}\mathrm{a}\mathrm{I}\mathrm{n}\mathrm{P}}_{2}$ heterojunction. found that ASPL can appear in both layers adjacent to heterojunction when excitation photon energy is higher than below-band-gap (BBG) luminescence. The intensity ${\mathrm{GaInP}}_{2}$-related shows an almost linear dependence on intensity. Time-resolved experiments...
Abstract Yeongil bay is a basin located in Pohang, South Korea. Numerous projects and researches have been conducted for carbon capture storage bay. The objectives of most studies were shifted from enhancing injection efficiency to ensuring safety dioxide (CO2) after the Pohang earthquake occurrence 2017. In this research, we present stepwise CO2 scenario, which gradually increases rate during early stage period. Furthermore, conduct sensitivity analyses on an optimal based variations...
Femtosecond two beam and three ( ${\ensuremath{\omega}}_{1},{\ensuremath{\omega}}_{1};{\ensuremath{\omega}}_{2}$) four-wave mixing (FWM) experiments on GaAs quantum wells have been performed using partially synchronized, independently tunable lasers with external jitter compensation. Heavy light hole beatings are observed these mutually incoherent lasers. FWM signals when ${\ensuremath{\omega}}_{2}$ is completely below the exciton energies, no spectral overlap absorption profile. These...
Qin, Y., Kabir, M. A., Wang, H. W., Lee, Y. H., Hong, S. Kim, J. Yook, J., D. S., C. Kwon, and W. 2013. Assessment of genetic diversity relationships based on RAPD AFLP analyses in Miscanthus genera landraces. Can. Plant Sci. 93: 171–182. In this study, molecular markers, random amplified polymorphic DNA (RAPD) fragment length polymorphism (AFLP) as well combined analysis were used to assess a reference set 38 accessions which 32 collected from South Korea 6 foreign countries. Using 30...
Abstract Ensemble Kalman filter is typically utilized to characterize reservoirs with high uncertainty. However, it requires a large number of reservoir models for stable and reliable update its members, resulting in simulation time. In this study, we propose sampling scheme using convolutional autoencoder principal component analysis fast channel characterization. The proposed method provides good initial similar the reference model gives successful quantification future performances...
Frequency mixing ( $2{\ensuremath{\omega}}_{1}\ensuremath{-}{\ensuremath{\omega}}_{2}$) is demonstrated in femtosecond nondegenerate four-wave (FWM) on GaAs multiple quantum wells using two synchronized, independently tunable lasers. The frequency component the spectrally resolved FWM coexists with exciton resonance, and it dominates over at high intensity detuning. This off-resonant present only for delays smaller than temporal pulse width, whereas resonant survives longer delays.
Abstract Ensemble-based methods involve using multiple models for model calibration to correct initial based on observed data. The assimilated ensemble allow probabilistic analysis of future production behaviors. It is crucial use good obtain reliable history matching and prediction both oil water productions especially channel reservoirs having high uncertainty heterogeneity. In this study, we propose a fast method by selecting streamline deep learning. proposed applied two cases 3D...
We have performed femtosecond and picosecond nondegenerate two-beam three-beam (ω1, ω1;ω2) four-wave mixing experiments by using two partially synchronized, independently tunable lasers with a simple sample-and-hold switch. When the jitter is compensated for externally, heavy- light-hole beating observed these mutually incoherent lasers, synchronous phases of oscillations detuning show that beats are true quantum beats. also see strong completely off-resonant signals, below-bandgap signals...
We perform degenerate and nondegenerate pump-probe experiments on bulk GaAs at 100 K below the band gap. mostly observe a negative differential transmission signal both in experiments. interpret our as due to two-photon absorption. This has different origin from normally considered gap renormalization for resonant excitations.
Femtosecond pump-probe (PP) differential reflectivity spectroscopy (DRS) and four-wave mixing (FWM) experiments were performed simultaneously to study the initial temporal dynamics of exciton line-shapes in GaN epilayers. Beats between A-B excitons found \textit{only for positive time delay} both PP FWM experiments. The rise at negative delay reflection spectra was much slower than signal or transmission (DTS) resonance. A numerical solution a six band semiconductor Bloch equation model...
Quantum interference between real and virtual polarizations is demonstrated in the time domain. Using a novel technique we can visualize excited state quantum amplitude its phase under off-resonant excitation.