A5078169515- Rocket and propulsion systems research
- Combustion and flame dynamics
- Advanced Combustion Engine Technologies
- Engineering Applied Research
- Heat transfer and supercritical fluids
- Combustion and Detonation Processes
- Semiconductor materials and devices
- Catalytic Processes in Materials Science
- Energetic Materials and Combustion
- Innovative Energy Harvesting Technologies
- Aerodynamics and Fluid Dynamics Research
- Spacecraft and Cryogenic Technologies
- Hydraulic and Pneumatic Systems
- Acoustic Wave Phenomena Research
- Ferroelectric and Negative Capacitance Devices
- Fire dynamics and safety research
- Refrigeration and Air Conditioning Technologies
- Catalysis and Oxidation Reactions
- Biodiesel Production and Applications
- Advanced Memory and Neural Computing
- Aerodynamics and Acoustics in Jet Flows
- Advanced Thermodynamic Systems and Engines
- Vehicle Noise and Vibration Control
- Vehicle emissions and performance
- Energy Harvesting in Wireless Networks
Seoul National University
1999-2025
Chungnam National University
2014-2024
Virginia Tech
2017-2021
University of Seoul
2015-2016
New Generation University College
2013
Samsung (South Korea)
2002-2012
Hyundai Motors (South Korea)
1998-2011
Czech Academy of Sciences, Institute of Physics
2010
Kia Motors (South Korea)
2009-2010
Korea Aerospace Research Institute
2003-2010
The resistive switching mechanism of 20- to 57-nm-thick TiO2 thin films grown by atomic-layer deposition was studied current-voltage measurements and conductive atomic force microscopy. Electric pulse-induced resistance repetitively (> a few hundred times) observed with ratio ⪢102. Both the low- high-resistance states showed linear log current versus voltage graphs slope 1 in low-voltage region where did not occur. thermal stability both conduction also studied. Atomic microscopy...
The evolution of ferroelectricity in undoped-HfO<sub>2</sub> thin films is systematically studied by controlling the deposition temperature during atomic layer deposition.
For the development of resistive memory devices using NiO, improvements several switching properties are required. In NiO cells with noble metal electrodes, broad dispersions parameters generally observed continuous switchings. We report in minimizing all thin IrO2 layers between and electrodes. The role on growth stabilization discussed.
The effects of the internal field and conduction mechanism carriers in ferroelectric Hf<sub>0.5</sub>Zr<sub>0.5</sub>O<sub>2</sub> thin films are systematically investigated by controlling in-depth profile oxygen vacancy concentrations.
10-nm-thick hafnium dioxide (HfO2) and aluminum-doped titanium (Al-doped TiO2, ATO) thin films were respectively interposed between the 20-nm-thick amorphous Zn–Sn–O (a-ZTO) channel layer 30-nm-thick silicon (SiO2) gate insulator for thin-film transistor (TFT) performance evaluation. Despite using identical atomic-layer deposition process, a-ZTO with higher Sn concentration deposited on HfO2 ATO film (Sn/Zn atomic ratio 0.82 0.81, respectively) than SiO2 (0.74). Ion interdiffusion Zn2+ Ti4+...
A theoretical model for the radially dependent effective piezoelectric coefficient and corresponding potential in intrinsic ZnO nanowires (NWs)/nanotubes (NTs) is presented. Substrate-bound structures oriented along c-axis with diameters of 100–5000 nm (NWs) inner 100–900 (NTs; fixed outer diameter, 1000 nm) were examined using finite element method analysis. The depended nonlinearly on NT/NW size, which we explain peak potentials. We propose that this can be used to judge degree enhancement NWs/NTs.
To measure the displacement of a shape memory alloy (SMA) coil spring actuator for feedback control, sensors larger than are normally required. In this study, novel method estimating an SMA without sensor is proposed. Instead sensor, inductance used displacement. Coil estimated by measuring voltage and transient response current. It has one-to-one relationship with not affected load. Previous methods using resistance measurements heavily load variations. The experimental results herein show...
Stochastic resonance is referred to as a physical phenomenon that manifest in nonlinear systems whereby weak periodic signal can be significantly amplified with the aid of inherent noise or vice versa. In this paper, stochastic considered harvest energy from two typical vibrations rotating shafts: random whirl vibration and stick-slip vibration. Stick-slip impose constant offset centrifugal force distort potential function harvester, leading asymmetry. A numerical analysis based on finite...
An electrostatic force microscopy (EFM) method has been used for the detection and control of microdomain in ferroelectric single crystal [triglycine sulfate (TGS)] thin film piezoelectric transducer (PZT). In this method, EFM is operated a dynamic contact mode that allows simultaneous measurement topographic domain contrast images. Through analysis between tip surface, surface charge density TGS obtained. Polarization obtained 2.7 μC/cm2 at room temperature. A complex pattern was written on...
Monitoring rail temperature is very important for determining the safe running speed of trains and to prevent buckling. In general, maximum variation internal can be >7 ℃ depending on point measurement. However, there as yet no sufficient information about how predict measurement represent thermal deformation due distribution. this study, authors report a new point, called representative at which measured. This considers average through structural analysis by adopting experimental actual...
The effect of baffle gaps on the damping enhancement a liquid rocket engine combustor has been elucidated through series tests, which include cold acoustic tests under both atmospheric and simulated viscous conditions combustion tests. injector-formed baffles, consist an array protruded coaxial injectors, were found to have much greater than conventional planar baffles. For several axial lengths, optimal capacitance achieved at 0.1 ∼ 0.2 mm gap. reason there exists gap is thought be mainly...
High-quality silicon oxide (SiO2) thin films are deposited by plasma-enhanced atomic layer deposition (PEALD) using bis(diethylamino)silane as a Si precursor and ammonia/oxygen plasmas at substrate temperature of 150°C. The SiO2 formed growth rate ∼0.137 nm/cycle in high purity. overall quality the PEALD-SiO2 assessed infrared spectroscopy, wet etch 0.5% hydrofluoric solution, Auger electron current-voltage analysis. low combination compares well with higher temperatures (350°C) oxygen plasma only.