Effect of Wavelength and Intensity of Light on a-InGaZnO TFTs under Negative Bias Illumination Stress

We investigated degradation mechanism of a-IGZO TFTs under NBIS with different wavelengths. and intensities IL of light. Negative gate bias was applied for 4000 s while drain and source were grounded, and illuminations with lambda = 450, 530, or 700 nm were applied. Illumination with photon energy exceeding similar to 2.3 eV (530 nm) induced noticeable change in threshold voltage shift Delta V-th, which can be interpreted in terms of ionization of oxygen vacancies V-O. In addition, I-L of blue illumination (450 nm) was varied from 6 to 200 lux and saturation in Delta V-th was observed after exceeding a certain I-L. We suggest that the saturation occurs because V-O-ionization rate is saturated by outward relaxation of metal atoms in the a-IGZO film. (C) The Author(s) 2016. Published by ECS.1174Ysciescopu

Phenotypic and Genetic Relationships between Kidney Function and Carotid Intima-Media Thickness in Koreans: The Healthy Twin Study

Background: The phenotypic and genetic relationships between carotid intima-media thickness (CIMT) and estimated glomerular filtration rate (eGFR) or urinary albumin-creatinine ratio (ACR) were evaluated in Korean twins and families. Methods: We recruited 688 participants (296 individual twins and 392 singletons, age 30-74 years) who were without myocardial infarction and stroke among participants in the Healthy Twin Study. eGFR was calculated using the Chronic Kidney Disease Epidemiology Collaboration equation. CIMT was measured using B-mode carotid ultrasound. Covariates were sex, Framingham risk scores, alcohol use, exercise, BMI, high-sensitivity C-reactive protein and triglycerides. Quantitative genetic and linear mixed analyses were performed. Results: In adjusted models there were associations between kidney function and CIMT with [beta] estimates ranging from -0.022 to -0.032 between eGFR and CIMT, and from 0.042-0.060 between ACR and CIMT. The covariate-adjusted heritabilities for eGFR, ACR and composite CIMT were 0.75, 0.32 and 0.45, respectively (p < 0.001). The adjusted genetic correlation between eGFR and CIMT was from -0.20 to -0.28 (p < 0.05), whereas there was no genetic correlation between ACR and CIMT. Conclusion: Kidney function is a surrogate marker of carotid atherosclerosis and further studies of the pleiotropic relationships between CIMT and eGFR are warranted. Copyright (C) 2012 S. Karger AG, BaselOAIID:oai:osos.snu.ac.kr:snu2012-01/102/0000040632/16SEQ:16PERF_CD:SNU2012-01EVAL_ITEM_CD:102USER_ID:0000040632ADJUST_YN:YEMP_ID:A077602DEPT_CD:902CITE_RATE:1.596FILENAME:phenotypic and genetic relationships between kidney function and carotid intima-media thickness in koreans the healthy twin study.pdfDEPT_NM:보건학과SCOPUS_YN:YCONFIRM:

Biomechanical Analysis in Five Bar Linkage Prototype Machine of Gait Training and Rehabilitation by IMU Sensor and Electromyography

The prototype machine of gait training and rehabilitation (MGTR) with a five-bar linkage structure was designed to improve the common end-effector type. Additionally, the study was conducted to evaluate the joint angle and muscle activity during walking for the evaluation of prototype: (1) Background: The gait rehabilitation systems are largely divided into exoskeletal type and end-effector type. The end-effector type can be improved a gait trajectory similar to normal gait according to this prototype. Therefore, a new design of prototype MGTR is proposed in this study. (2) Methods: The gait experience was conducted with thirteen healthy male subjects using an inertial measurement unit (IMU) sensor and electromyography (EMG). It was compared that the hip and knee joints and the muscle activity between the normal gait and MGTR. (3) Results: The results showed that there was a high correlation between the knee joint angle for normal gait and MGTR. The range of motion (RoM) was small for the MGTR. The EMG results showed that the activation of the rectus femoris muscle was most similar to the normal gait and MGTR. (4) Conclusions: The characteristics of the kinematic variables of the subjects varied widely. It is necessary to modify the machine so that the link length can be adjusted in consideration of various segment lengths of patients

Smoothed particle hydrodynamics modeling and analysis of oxide reduction process for uranium oxides

A common kinetic feature for oxide reduction chemical/electrochemical processes is oxygen transport via a porous metallic layer, which has been considered as a rate-determining step for reducing uranium oxides to metallic uranium. Accounting this kinetic behavior must involve the resolution of the moving reactive interface between shrinking oxide and expanding metal phases. This study presents a numerical model using smoothed particles hydrodynamics (SPH) to effectively deal with the evolution of the shrinking core reaction interface and oxygen transport via mass transfer of lithium oxide (Li2O) species in multiple mass transfer domains. We successfully validated the proposed model against a theoretical derivation for the oxide reduction process handling a shrinking oxide core with molten salt and metal ash medium on a simple planar geometry. Armed with successful validation results, the model examined a realistic reactant geometry to extend the arguments beyond the one-dimensional analyses, allowing the proposed model to apply to general application scenarios with multi-dimensional geometry. This study demonstrated that the proposed model could simulate and evaluate an arbitrary reaction basket design without iterative experimental trials, which is prohibitive for a scaled high-temperature molten salt study in an inert environment. The construct potentially provides not only deep insights on multiphysics behaviors governing the process dynamics but also a robust framework for evaluating and screening candidate basket designs in the most cost-effective manner. Published by Elsevier Ltd.N

Development of Immersive VR Device for Gait Training Rehabilitation with Biofeedback System-Preliminary Study

Gait-training rehabilitation machines (MGTR) are contraptions used for the motor rehabilitation of patients with movement disorders resulting from stroke and Parkinson’s disease. This study was aimed at implementing a walking pattern similar to the normal gait. Background: Immersion and motivation are important factors in repetitive rehabilitation exercises. This was addressed by synchronizing walking speed and virtual reality (VR) visons to provide a sense of immersion in a convergence environment of MGTR and VR. Methods: The difference in joint angle and gait event was confirmed when the step length was adjusted in this system to control the joint movement. Results: It was confirmed that the joint range of motion also increased significantly as the step length increased. Conclusions: The possibility of developing a more immersive MGTR system that feedback the actual gait state in the VR system was confirmed by applying that the joint movement varies according to the step length. It will be possible to provide an immersive feeling more similar to the actual walking by modifying the gait trajectory of the MGTR

Pulse duration effect during pulsed gate-bias stress in a-InGaZnO thin film transistors

We investigated how the zero-voltage duration (0Vd) affects the tendency of degradation during pulsed gate bias stress in a-InGaZnO thin film transistors (TFTs). DC or pulsed negative bias illumination stress (NBIS) or positive bias stress (PBS) was applied to the TFTs for effective stress time of 4,000 s. While pulsed bias stress was being applied, stress-voltage duration (SVd) was set as either 10 s or 1 s per cycle, and 0Vd was varied from 100% to 1% of the SVd. During NBIS, degradation in both threshold voltage and sub-threshold slope became increasingly severe as 0Vd was shortened. However, during pulsed PBS, these trends were almost absent. These different tendencies may occur because the cause of each stress-induced degradation is fundamentally dissimilar; NBIS involves ionization of oxygen vacancies, whereas PBS involves electron trapping. The proposed mechanism was supported by additional bias stress tests on TFTs that had been immersed in H2O, where hydrogen became dominant factor causing the degradation.11Nsciescopu

Degradation process by effect of water molecules during negative bias temperature stress in amorphous-InGaZnO thin-film transistor

We explained how H2O degrades amorphous-InGaZnO thin-film transistors. H2O caused serious degradation only during negative bias temperature stress (NBTS). Degradation was caused by molecules that were absorbed or diffused from the outside. We suggest that degradation under NBTS is caused by the migration of hydrogen ions among oxygen vacancies. Under illumination, the soaking time t(S) did not affect the threshold voltage shift Delta V-th. We consider that this independence occurred because illumination caused ionization from the oxygen vacancy V-O state to V-O(2+), which impeded hydrogen migration induced by electric field and thereby protected the device from degradation after exposure to water. (c) 2017 The Japan Society of Applied Physics112sciescopu

Relationship between Detrapping of Electrons and Negative Gate Bias during Recovery Process in a-InGaZnO Thin Film Transistors

The relationship between detrapping of electrons and negative gate bias in amorphous InGaZnO thin film transistors (a-IGZO TFTs) is investigated. In these devices, positive gate-bias stress (PBS) traps electrons at the gate insulator (GI) or at the interface between the channel and the GI, and creates acceptor-like states, which the authors speculate may be oxygen interstitials or zinc vacancies. In contrast, negative gate-bias stress (NBS) increases donor-like states, which are speculated as ionized oxygen vacancies, near the interface. When subsequent negative gate bias (SNB) is applied to a TFT after PBS, electrons are detrapped and donor-like states are increased simultaneously. Measurements with various SNB and PBS conditions suggests that SNB accelerates detrapping of electrons, and that those detrapped electrons interrupts the increase of donor-like states.11Nsciescopu