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"Park, Min-Kyu"
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Charge-trap synaptic device with polycrystalline silicon channel for low power in-memory computing
Processing-in-memory (PIM) is gaining tremendous research and commercial interest because of its potential to replace the von Neumann bottleneck in current computing architectures. In this study, we implemented a PIM hardware architecture (circuit) based on the charge-trap flash (CTF) as a synaptic device. The PIM circuit with a CT memory performed exceedingly well by reducing the inference energy in the synapse array. To evaluate the image recognition accuracy, a Visual Geometry Group (VGG)-8 neural network was used for training, using the Canadian Institute for Advanced Research (CIFAR)-10 dataset for off-chip learning applications. In addition to the system accuracy for neuromorphic applications, the energy efficiency, computing efficiency, and latency were closely investigated in the presumably integrated PIM architecture. Simulations that were performed incorporated cycle-to-cycle device variations, synaptic array size, and technology node scaling, along with other hardware-sense considerations.
Journal Article
Fast-switching laterally virtual-moving microlens array for enhancing spatial resolution in light-field imaging system without degradation of angular sampling resolution
We present an electrically controllable fast-switching virtual-moving microlens array (MLA) consisting of a stacked structure of two polarization-dependent microlens arrays (PDMLAs) with optical orthogonality, where the position of the two stacked PDMLAs is shifted by half the elemental pitch in the diagonal direction. By controlling the polarization of the incident light without the physical movement of the molecules comprising the virtual-moving MLA, the periodic sampling position of the MLA can be switched fast using a polarization-switching layer based on a fast-switching liquid crystal cell. Using the fast-switching virtual-moving MLA, the spatial-resolution-enhanced light-field (LF) imaging system was demonstrated without a decrease in the angular sampling resolution as compared to the conventional LF imaging system comprising a passive MLA; two sets of elemental image arrays were captured quickly owing to the short switching time of the virtual-moving MLA of 450 μs. From the two captured sets of the elemental array image, four-times resolution-enhanced reconstruction images of the directional-view and depth-slice images could be obtained.
Journal Article
Titanium dioxide nanoparticles oral exposure to pregnant rats and its distribution
Background
Titanium dioxide (TiO
2
) nanoparticles are among the most manufactured nanomaterials in the industry, and are used in food products, toothpastes, cosmetics and paints. Pregnant women as well as their conceptuses may be exposed to TiO
2
nanoparticles; however, the potential effects of these nanoparticles during pregnancy are controversial, and their internal distribution has not been investigated. Therefore, in this study, we investigated the potential effects of oral exposure to TiO
2
nanoparticles and their distribution during pregnancy. TiO
2
nanoparticles were orally administered to pregnant Sprague-Dawley rats (12 females per group) from gestation days (GDs) 6 to 19 at dosage levels of 0, 100, 300 and 1000 mg/kg/day, and then cesarean sections were conducted on GD 20.
Results
In the maternal and embryo-fetal examinations, there were no marked toxicities in terms of general clinical signs, body weight, food consumption, organ weights, macroscopic findings, cesarean section parameters and fetal morphological examinations. In the distribution analysis, titanium contents were increased in the maternal liver, maternal brain and placenta after exposure to high doses of TiO
2
nanoparticles.
Conclusion
Oral exposure to TiO
2
during pregnancy increased the titanium concentrations in the maternal liver, maternal brain and placenta, but these levels did not induce marked toxicities in maternal animals or affect embryo-fetal development. These results could be used to evaluate the human risk assessment of TiO
2
nanoparticle oral exposure during pregnancy, and additional comprehensive toxicity studies are deemed necessary considering the possibility of complex exposure scenarios and the various sizes of TiO
2
nanoparticles.
Journal Article
Effects of the COVID-19 lockdown on criteria air pollutants in the city of Daegu, the epicenter of South Korea’s outbreak
The outbreak of COVID-19 in Daegu, South Korea, early in 2020 has led this metropolitan city to become one of the major hotspots in the world. This study investigates the association of meteorology and the new daily COVID-19 confirmed cases and the effects of the city lockdown on the variation in criteria air pollutants (CAPs) in Daegu. Ambient temperature and relative humidity were negatively correlated to the new daily cases and played an important role in the spread of COVID-19. Wind speed could enhance the virus transmission through the inhalation of aerosols and/or droplets and contact with fomites. The lockdown has directly decreased the concentrations of CAPs. In particular, reductions of 3.75% (PM
10
), 30.9% (PM
2.5
), 36.7% (NO
2
), 43.7% (CO), and 21.3% (SO
2
) between the period before and during the outbreak were observed over the entire city. An increase in O
3
(71.1%) was affected by natural processes and photochemical formation other than the lockdown effects. The three central districts were the areas most affected by the virus and showed the highest reductions in CAPs (except for O
3
) during the outbreak. Apart from the influence of the lockdown, the decreasing trend in CAPs may be a result of the actions taken by the government to mitigate air pollutants nationwide since 2019. The results of this study can be useful for government and medical organizations to understand the behavior of the virus in the atmosphere. Further studies are necessary to explore the detailed influences of the lockdown on the environment and public life.
Journal Article
Theophylline Attenuates the Release of Cardiovascular Disease-Related Triglyceride and Cholesterol by Inhibiting the Activity of Microsomal Triglyceride Transfer Protein in Rat Hepatocytes
Background/Objectives: Cardiovascular diseases (CVD) remain the leading cause of diet-related mortality, with hepatic overproduction of very-low-density lipoprotein (VLDL) being a central driver of dyslipidemia. The microsomal triglyceride transfer protein (MTP) is essential for this process, and its activity is negatively regulated by cyclic adenosine monophosphate (cAMP). Theophylline, a methylxanthine found in tea, increases intracellular cAMP. This study aimed to evaluate whether physiologically relevant concentrations of theophylline could beneficially modulate lipoprotein secretion in an ex vivo model of diet-induced MTP activation. Methods: Primary hepatocytes were isolated from rats fed a high-fat, high-carbohydrate diet (HFCD). Cells were treated with 100 µM theophylline, and the secretion of triglyceride (TG), total cholesterol (TC), VLDL-cholesterol (VLDL-C), and HDL-cholesterol (HDL-C) was quantified. Hepatocellular MTP activity and atherogenic indices were also assessed. Results: Compared to untreated control cells, theophylline treatment significantly reduced the secretion of TG by 6% and TC by 24%. Specifically, VLDL-C secretion decreased by 6%, while HDL-C secretion increased substantially by 93%. These lipid-modulating effects were correlated with a 6.9% reduction in MTP activity. Consequently, significant improvements were observed in the atherogenic indices TG/HDL-C, TC/HDL-C, and the atherogenic index (AI) (p < 0.01). Conclusions: Our findings demonstrate that physiologically attainable concentrations of theophylline rebalance lipoprotein secretion by suppressing hepatic MTP activity, shifting the lipid profile toward an anti-atherogenic state. These results highlight the potential of theophylline as a functional dietary component for mitigating diet-induced dyslipidemia and reducing cardiovascular risk.
Journal Article
Review of the Current State of Freely Accessible Web Tools for the Analysis of 16S rRNA Sequencing of the Gut Microbiome
Owing to the emergence and improvement of high-throughput technology and the associated reduction in costs, next-generation sequencing (NGS) technology has made large-scale sampling and sequencing possible. With the large volume of data produced, the processing and downstream analysis of data are important for ensuring meaningful results and interpretation. Problems in data analysis may be encountered if researchers have little experience in using programming languages, especially if they are clinicians and beginners in the field. A strategy for solving this problem involves ensuring easy access to commercial software and tools. Here, we observed the current status of free web-based tools for microbiome analysis that can help users analyze and handle microbiome data effortlessly. We limited our search to freely available web-based tools and identified MicrobiomeAnalyst, Mian, gcMeta, VAMPS, and Microbiome Toolbox. We also highlighted the various analyses that each web tool offers, how users can analyze their data using each web tool, and noted some of their limitations. From the abovementioned list, gcMeta, VAMPS, and Microbiome Toolbox had several issues that made the analysis more difficult. Over time, as more data are generated and accessed, more users will analyze microbiome data. Thus, the availability of free and easily accessible web tools can enable the easy use and analysis of microbiome data, especially for those users with less experience in using command-line interfaces.
Journal Article
Selective DUV Femtosecond Laser Annealing for Electrical Property Modulation in NMOS Inverter
Amorphous indium gallium zinc oxide (a-IGZO) is widely used as an oxide semiconductor in the electronics industry due to its low leakage current and high field-effect mobility. However, a-IGZO suffers from notable limitations, including crystallization at temperatures above 600 °C and the high cost of indium. To address these issues, nitrogen-doped zinc oxynitride (ZnON), which can be processed at room temperature, has been proposed. Nitrogen in ZnON effectively reduces oxygen vacancies (VO), resulting in enhanced field-effect mobility and improved stability under positive bias stress (PBS) compared to IGZO. In this study, selective deep ultraviolet femtosecond (DUV fs) laser annealing was applied to the channel region of ZnON thin-film transistors (TFTs), enabling rapid threshold voltage (Vth) modulation within microseconds, without the need for vacuum processing. Based on the electrical characteristics of both Vth-modulated and pristine ZnON TFTs, an NMOS inverter was fabricated, demonstrating reliable performance. These results suggest that laser annealing is a promising technique, applicable to various logic circuits and electronic devices.
Journal Article
On‐Chip Annealing Using Embedded Micro‐Heater for Highly Sensitive and Selective Gas Detection
The demand for gas sensing systems that enable fast and precise gas recognition is growing rapidly. However, substantial challenges arise from the complex fabrication process of sensor arrays, time‐consuming data transmission to an external processor, and high energy consumption in multi‐stage data processing. In this study, a gas sensing system using on‐chip annealing for fast and power‐efficient gas detection is proposed. By utilizing a micro‐heater embedded in the gas sensor, the sensing material of adjacent sensors in the same substrate can be easily varied without further fabrication steps. The response to oxidizing gas is constrained in metal oxide (MOX) sensing material with small grain sizes, as the depletion width of grain cannot extend beyond the grain size during the gas reaction. On the other hand, the response to reducing gases and humidity, which decrease the depletion width, is less affected by grain sizes. A readout circuit integrating a differential amplifier and dual FET‐type gas sensors effectively emphasizes the response to oxidizing gases by canceling the response to reducing gases and humidity. The selective on‐chip annealing method is applicable to various MOX sensing materials, demonstrating its potential for application in commercial fields due to its simplicity and expandability.
By utilizing embedded micro‐heaters for post‐deposition annealing, metal oxide grain size and gas responses of adjacent sensors in the same substrate can be controlled without further fabrication steps. The proposed dual FET‐type gas sensors with on‐chip annealing can directly determine the gas concentration in a mixed gas environment, introducing a new approach for a real‐time energy‐efficient gas sensing system.
Journal Article
Characteristics of metal contamination in paddy soils from three industrial cities in South Korea
Paddy soil contamination is directly linked to human dietary exposure to toxic chemicals via crop consumption. In Korea, rice paddy fields are often located around industrial complexes, a major anthropogenic source of metals. In this study, rice paddy soils were collected from 50 sites in three industrial cities to investigate the contamination characteristics and ecological risk of metals in the soils. The cities studied and their major industries are as follows: Ulsan (petrochemical, nonferrous, automobile, and shipbuilding), Pohang (iron and steel), and Gwangyang (iron and steel, nonmetallic, and petrochemical). Thirteen metals (Al, As, Ba, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, V, and Zn) were analyzed using inductively coupled plasma–optical emission spectrometry (ICP–OES). The mean concentration of Cd (1.98 mg/kg) exceeded the soil quality guideline of Canada (1.4 mg/kg), whereas concentrations of other metals were under the standards of both Korea and Canada. Generally, levels of metal concentrations decreased with increasing distance from industrial complexes. Among the three cities, Pohang showed high concentrations of Zn (142.2 mg/kg), and Ulsan and Gwangyang showed high concentrations of Cr (33.9 mg/kg) and Ba (126.4 mg/kg), respectively. These contamination patterns were influenced by the different major industries of each city, which was clearly demonstrated by the principal component analysis results. Pollution indices suggested that As, Cd, Pb, and Zn were enriched in the paddy soils via anthropogenic activities. Comprehensive potential ecological risk indices were at considerable levels for most sites, especially because of major contributions from As and Cd, which can pose potential ecological threats.
Journal Article