A5065653327- Spectroscopy and Quantum Chemical Studies
- Spectroscopy and Laser Applications
- Advanced Fiber Laser Technologies
- Laser-Matter Interactions and Applications
- Photochemistry and Electron Transfer Studies
- Spectroscopy Techniques in Biomedical and Chemical Research
- Photosynthetic Processes and Mechanisms
- Sensorless Control of Electric Motors
- Cold Atom Physics and Bose-Einstein Condensates
- Electric Motor Design and Analysis
- Photonic and Optical Devices
- Photoreceptor and optogenetics research
- Advanced Frequency and Time Standards
- Mechanical and Optical Resonators
- Magnetic Properties and Applications
- Quantum Information and Cryptography
- Multilevel Inverters and Converters
- Luminescence and Fluorescent Materials
- Analytical Chemistry and Sensors
- Genetic Associations and Epidemiology
- Molecular spectroscopy and chirality
- Electron Spin Resonance Studies
- Cholesterol and Lipid Metabolism
- Advanced NMR Techniques and Applications
- Mass Spectrometry Techniques and Applications
Chungbuk National University
2023-2025
Pohang University of Science and Technology
2012-2023
Princeton University
2021-2022
Yonsei University
2021-2022
Institute for Basic Science
2018-2021
Electronics and Telecommunications Research Institute
2014
Korea Center for Disease Control and Prevention
2013
Korea National Institute of Health
2002-2012
Korea Institute of Ceramic Engineering and Technology
2011
Korea University
2011
Although approximately 25 common genetic susceptibility loci have been identified to be independently associated with breast cancer risk through genome-wide association studies (GWAS), the variants reported date only explain a small fraction of heritability cancer. Furthermore, GWAS-identified were primarily in women European descent. To evaluate previously Korean and identify additional novel variants, we conducted three-stage GWAS that included 6,322 cases 5,897 controls. In validation...
In a very high-speed operation (≥ 50 kr/min), the iron loss is not sufficiently small to be neglected. The alters angle and magnitudes of back electromotive force (EMF). resistance representing calculated priori from finite-element analysis incorporated into lookup table, because it dependent on current magnitudes. Utilizing extended EMF method, sensorless control method developed for model that takes account. proposed overcomes difference in region, performance demonstrated through...
Electrically excited synchronous motors are designed to have high power density for electric vehicle applications. During a high-torque operation, severe nonlinearities associated with saturation observed: change of inductances, emergence cross-coupling effects, variation back EMF coefficient, etc. A flux linkage map over the current plane is obtained via finite-element analysis (FEA), and it fitted by third-order polynomial use least square method. Then, grouping terms polynomial,...
Abstract Mid‐infrared (MIR) spectroscopy has emerged as a pivotal tool for studying molecular dynamics with ultrafast time resolution, allowing precise investigations into structural changes, chemical reactions, and energy transfer processes. This review explores the transformative capabilities of femtosecond MIR techniques such pump‐probe (PP) two‐dimensional infrared (2DIR) spectroscopy, which offer unparalleled specificity in probing vibrations exploring complicated landscapes across...
Dual frequency comb (DFC) nonlinear spectroscopy is an emerging technique that can be used to study a variety of molecular responses by exploiting the automatic pulse-to-pulse time delay scanning and fast data acquisition characteristics DFC techniques. Here, we propose DFC-based photon echo (DFC-PES), where two optical lasers have slightly different repetition rates are also allowed carrier frequencies. We first demonstrate our theoretical approach for linear spectroscopy. Then, signals...
The reaction dynamics of a photochemical is typically described by coordinates based on the Born–Oppenheimer (BO) approximation. A strong interaction between electrons and nuclei, conventionally occurring at conical intersections, however, breaks BO approximation has major consequences for efficiency reaction. Despite its importance, related studies into non-BO are scarce. Here, we investigate excited-state intramolecular proton transfer (ESIPT) in 10-hydroxybenzo[h]quinoline (HBQ). Two...
Maternally inherited mitochondrial DNA (mtDNA) has been suggested to be a genetic factor for diabetes. Reports have shown decrease of mtDNA content in tissues diabetic patients. We investigated the effects depletion on glucose metabolism by use ρ 0 SK-Hep1 human hepatoma cells, whose was depleted long-term exposure ethidium bromide. The cells failed hyperpolarize membrane potential response stimulation. Intracellular ATP content, glucose-stimulated production, uptake, steady-state mRNA and...
Coherent nuclear wave packet motions in an electronic excited state of a molecule are measured directly by time-resolved spontaneous fluorescence spectroscopy with unprecedented time resolution using two-photon absorption excitation and upconversion noncollinear sum frequency generation. With estimated approximately 25 fs, vibrational modes up to 1600 cm-1 recorded for coumarin 153 ethanol. Two-color transient at 13 fs confirm the result. Vibrational displacements between ground states...
We experimentally demonstrate a dual-frequency comb-based transient absorption (DFC-TA) technique, which has 12 fs time resolution and an ultrafast scan rate. Here, the fast rate is achieved by employing asynchronous optical sampling (ASOPS), utilizes two independent mode-locked lasers with slightly detuned repetition rates. The ASOPS approach advantageous because photodegradation damage of sample during TA measurements can be minimized gated sampling. show that vibrational electronic...
Ultrafast intersystem crossing (ISC) of ruthenium complexes is time-resolved directly. Coherent nuclear wave packets suggest that metal–ligand stretching or symmetry breaking vibrational modes are strongly coupled with the ISC.
How atoms and electrons in a molecule move during chemical reaction how rapidly energy is transferred to or from the surroundings can be studied with flashes of laser light. However, despite prolonged efforts develop various coherent spectroscopic techniques, lack an all-encompassing method capable both femtosecond time resolution nanosecond relaxation measurement has hampered applications studying correlated electron dynamics vibrational coherences functional materials biological systems....
Lensless digital holography (LDH) is gaining considerable attention lately due to a simple experimental setup, wide field-of-view, and three-dimensional (3D) imaging capability. Since the resolution of LDH limited by Nyquist frequency detector array, major drawback resolution, lot efforts were made enhance LDH. Here we propose demonstrate fast noniterative sub-pixel shifting super-resolution technique that can effectively factor two. We provide detailed frequency-domain formulae for our...
Exciton relaxation dynamics in multichromophore systems are often modeled using Redfield theory, where bath fluctuations mediate the among exciton eigenstates. Identifying vibrational or phonon modes that implicated allows more detailed understanding of dynamics. Here we focus on a well-studied light-harvesting II complex (LH2) isolated from photosynthetic purple bacterium Rhodoblastus acidophilus strain 10050. Using two synchronized mode-locked lasers, carried out polarization-dependent...
Electrically excited synchronous motors (EESM) are designed to have high power density for electric vehicle (EV) applications. Thus, severe nonlinearity is observed during torque operation. The associated with core saturation modeled by incorporating the cross coupling inductances which also behave nonlinearly. analytic equation yielded good results that matched well FEM data and experimental data. Further, an extended maximum per ampere (MTPA) method was proposed EESM model inductances.
A complete understanding of a photochemical reaction dynamics begins with real-time measurements both electronic and vibrational structures photoexcited molecules. Time-resolved impulsive stimulated Raman spectroscopy (TR-ISRS) femtosecond actinic pump, probe pulses is one the incisive techniques enabling to investigate structural changes Herein, we demonstrate that such TR-ISRS feasible synchronized triple mode-locked lasers without using any time-delay devices. Taking advantage precise...
Oscillatory features observed in two-dimensional electronic spectroscopy (2DES) manifest coherent vibrational and dynamics even the interplay of them. Recently, we developed a 2DES technique utilizing pair synchronized repetition-frequency-stabilized lasers, which enables wide dynamic range measurements signals rapidly. Here, apply this dual-laser to investigate energy transfer (EET) process bacterial light-harvesting complex II consisting B800 B850 circular aggregates at ambient...
We demonstrate that a dual frequency comb-transient absorption (DFC-TA) technique can be combined with time-domain interferometric detection to measure both the transient and refraction spectra of molecules in solution. To do this, pump–probe signal field DFC-TA is allowed interfere time-delayed local oscillator time domain. show this DFC spectroscopy (DFC-IPS) has unique ability extract phase amplitude information on using just single-scan data, while conventional techniques require an...
Time-domain spectroscopies with time resolution shorter than the vibrational periods of interest were employed to reveal reaction kinetics and molecular dynamics intramolecular charge transfer (ICT) thioflavin T in liquids. Time-resolved fluorescence spectra provided detailed kinetics, wave packets observed time-resolved transient absorption structural information on intermediate. Upon photoexcitation, Franck-Condon state undergoes relaxation minor conformational change form a stable planar...
Recent advances in single-photon femtosecond spectroscopy have highlighted the power of entangled photons probing properties materials, previously inaccessible through semiclassical spectroscopic approaches. In this study, we theoretically propose a new single-photon-based time-resolved technique termed transient stimulated emission (SP-TSE). SP-TSE not only enables selective investigation singly excited superposition states but also harnesses quantum mechanical nature for efficient data...
Cholesterol-rich diet impairs endothelial NO synthase (eNOS) and enhances inducible NOS (iNOS) expression. In this study, we investigated effects of cholesterol on iNOS expression in high-fat-fed rat models, HepG2 RAW264.7 cells. The high-fat increased the plasma total level 6-7 fold low-density lipoprotein (LDL-C) approximately 70 slightly lipid peroxidation as determined by thiobarbituric acid-reactive substance assay. also nitric oxide (NO) concentrations up to 5 fold, induced mRNA liver....