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result(s) for
"Jeong, Junhyuk"
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A Novel Computational Approach for the Discovery of Drug Delivery System Candidates for COVID-19
by
Jeong, Junhyuk
,
Han, Hyo-Sang
,
Cho, Taeheum
in
A549 Cells
,
Anti-Inflammatory Agents - chemistry
,
Anti-Inflammatory Agents - therapeutic use
2021
In order to treat Coronavirus Disease 2019 (COVID-19), we predicted and implemented a drug delivery system (DDS) that can provide stable drug delivery through a computational approach including a clustering algorithm and the Schrödinger software. Six carrier candidates were derived by the proposed method that could find molecules meeting the predefined conditions using the molecular structure and its functional group positional information. Then, just one compound named glycyrrhizin was selected as a candidate for drug delivery through the Schrödinger software. Using glycyrrhizin, nafamostat mesilate (NM), which is known for its efficacy, was converted into micelle nanoparticles (NPs) to improve drug stability and to effectively treat COVID-19. The spherical particle morphology was confirmed by transmission electron microscopy (TEM), and the particle size and stability of 300–400 nm were evaluated by measuring DLSand the zeta potential. The loading of NM was confirmed to be more than 90% efficient using the UV spectrum.
Journal Article
Interplay between electrochemical reactions and mechanical responses in silicon–graphite anodes and its impact on degradation
2021
Durability of high-energy throughput batteries is a prerequisite for electric vehicles to penetrate the market. Despite remarkable progresses in silicon anodes with high energy densities, rapid capacity fading of full cells with silicon–graphite anodes limits their use. In this work, we unveil degradation mechanisms such as Li
+
crosstalk between silicon and graphite, consequent Li
+
accumulation in silicon, and capacity depression of graphite due to silicon expansion. The active material properties, i.e. silicon particle size and graphite hardness, are then modified based on these results to reduce Li
+
accumulation in silicon and the subsequent degradation of the active materials in the anode. Finally, the cycling performance is tailored by designing electrodes to regulate Li
+
crosstalk. The resultant full cell with an areal capacity of 6 mAh cm
−2
has a cycle life of >750 cycles the volumetric energy density of 800 Wh L
−1
in a commercial cell format.
The degradation in silicon-graphite anodes is originated from Li ion crosstalk between silicon and graphite, and the pressure-induced staging transition of the graphite. Here, the authors demonstrate a prismatic cell with improved volumetric energy density and cycle stability by targeted solving above issues.
Journal Article
Developing a Motor Imagery-Based Real-Time Asynchronous Hybrid BCI Controller for a Lower-Limb Exoskeleton
by
Kim, Keun Tae
,
Kim, Laehyun
,
Kim, Hyungmin
in
Brain-Computer Interfaces
,
Electroencephalography
,
Exoskeleton Device
2020
This study aimed to develop an intuitive gait-related motor imagery (MI)-based hybrid brain-computer interface (BCI) controller for a lower-limb exoskeleton and investigate the feasibility of the controller under a practical scenario including stand-up, gait-forward, and sit-down. A filter bank common spatial pattern (FBCSP) and mutual information-based best individual feature (MIBIF) selection were used in the study to decode MI electroencephalogram (EEG) signals and extract a feature matrix as an input to the support vector machine (SVM) classifier. A successive eye-blink switch was sequentially combined with the EEG decoder in operating the lower-limb exoskeleton. Ten subjects demonstrated more than 80% accuracy in both offline (training) and online. All subjects successfully completed a gait task by wearing the lower-limb exoskeleton through the developed real-time BCI controller. The BCI controller achieved a time ratio of 1.45 compared with a manual smartwatch controller. The developed system can potentially be benefit people with neurological disorders who may have difficulties operating manual control.
Journal Article
Phase patterning of liquid crystal elastomers by laser-induced dynamic crosslinking
2024
Liquid crystal elastomers hold promise in various fields due to their reversible transition of mechanical and optical properties across distinct phases. However, the lack of local phase patterning techniques and irreversible phase programming has hindered their broad implementation. Here we introduce laser-induced dynamic crosslinking, which leverages the precision and control offered by laser technology to achieve high-resolution multilevel patterning and transmittance modulation. Incorporation of allyl sulfide groups enables adaptive liquid crystal elastomers that can be reconfigured into desired phases or complex patterns. Laser-induced dynamic crosslinking is compatible with existing processing methods and allows the generation of thermo- and strain-responsive patterns that include isotropic, polydomain and monodomain phases within a single liquid crystal elastomer film. We show temporary information encryption at body temperature, expanding the functionality of liquid crystal elastomer devices in wearable applications.
Lack of local phase patterning in liquid crystal elastomers has hindered their broad implementation. The authors report a laser-induced dynamic crosslinking approach with allyl sulfide groups to achieve reconfigurable high-resolution patterning of multiple liquid crystalline phases in a single film.
Journal Article
Rosuvastatin Versus Atorvastatin for Cardiovascular Disease Risk in Patients with Type 2 Diabetes: A Korean Cohort Study
by
Chang, Junhyuk
,
Kim, Chaeyoon
,
Park, Rae Woong
in
Cardiac arrest
,
Cardiovascular disease
,
Cardiovascular diseases
2025
: Rosuvastatin and atorvastatin are indicated for cardiovascular protection in patients with type 2 diabetes (T2D) but may differ in clinical effectiveness and safety. This study compared real-world cardiovascular and safety outcomes associated with rosuvastatin versus atorvastatin in patients with T2D, with an emphasis on older adults.
: This retrospective cohort study used electronic health records from 10 Korean hospitals standardized to the Common Data Model. Adults (≥18 years) with T2D who were newly prescribed rosuvastatin or atorvastatin were included. After propensity score matching, primary outcomes (myocardial infarction [MI], heart failure, stroke, cardiac arrest, and in-hospital death), secondary outcomes (peripheral arterial disease [PAD] and glaucoma), and safety outcomes (acute kidney injury, cataract, and myalgia) were compared. Subgroup and sensitivity analyses were conducted among patients aged ≥65 years.
: Among 49,034 patients (rosuvastatin, 16,123; atorvastatin, 32,911), baseline characteristics were well balanced. Across all participating hospitals, the comparative analyses showed no meaningful differences in cardiovascular or safety outcomes between the two statins. However, among patients aged ≥65 years, rosuvastatin was associated with a higher risk of PAD (hazard ratio [HR] 1.19; 95% confidence interval [CI] 1.03-1.38), and this finding was consistent in sensitivity analysis (HR 1.31; 95% CI 1.01-1.70).
: Rosuvastatin and atorvastatin demonstrated comparable cardiovascular effectiveness and safety. Although rosuvastatin was associated with a modestly higher incidence of PAD in older adults, the difference was small. From a clinical perspective, these findings underscore the importance of individualized statin therapy tailored to patient-specific factors such as age, comorbidity, and vascular health. Overall, both statins provide overall therapeutic equivalence for cardiovascular prevention.
Journal Article
Development of a 4 K two-stage commercial cooler assisted J-T with off-the-shelf mini compressor
2025
The helium compressor system for a miniaturized 4 K J-T cooler has been developed by using a set of commercial compressors. The considered cooler is intended to provide 10 mW of cooling capacity for a superconducting nanowire single photon detector (SNSPD) or for other quantum information devices. The cooler structure consists of an auxiliary 2-stage GM cooler to precool the helium stream and operate the radiation shields; three recuperators; an expansion orifice; and an evaporator. Two commercial miniaturized compressors, originally intended for R134a, have been repurposed for helium. Additionally, a custom oil removal system has been developed to provide a helium flow free of oil mist and other contaminants that may clog the expansion orifice. A model of the thermodynamic cycle was used to obtain the optimal coldhead temperatures. Subsequently, a numerical simulation of the recuperators has been employed to evaluate the required pressures and mass flow rate from the compressor. Lastly, the compressors and the oil removal system have been tested for similar operating conditions.
Journal Article
Development of switchless thin-plate sorption compressor and miniaturized check valves for 5 K J- T cooler
2024
The cell of the sorption compressor developed in this paper has a thin-plate shape to accelerate the pressure swing by reducing the heating and cooling periods. Its width, height and thickness are 100 mm, 100 mm and 4.6 mm, respectively. Two identical cells filled with 22.8 g of charcoal mass are operated alternately to generate and maintain significant pressure difference for the 5 K J-T cooler with the pre-cooling temperature of 15 K. The designed nominal pressure of the high-pressure and the low-pressure parts of the J-T cooler are 1000 kPa and 196 kPa, respectively. The mass flow rate and the pressure gradient of the thin-plate sorption compressor with commercial check valves are measured experimentally. As the performance of the compressor, COP of the compressor is estimated and compared with the compressor of previous researches. Furthermore, to reduce leakage rate and thermal inertia of check valves in the compressor, miniaturized check valve is specially designed and fabricated to replace the commercial valve. When the flow direction is reversed in the valve, the leakage is passively prevented by contacting two metal surfaces at low temperature (30 K). The essential parts of the valve are critically miniaturized to reduce the overall thermal inertia of the compressor system. The cracking pressure and the leakage rate of the developed check valve and the commercial check valve are measured to compare.
Journal Article
Quantification of Blood Flow Velocity in the Human Conjunctival Microvessels Using Deep Learning-Based Stabilization Algorithm
by
Kim, Dae-Yu
,
Jo, Hang-Chan
,
Jeong, Hyeonwoo
in
Algorithms
,
Blood
,
blood flow velocity quantification
2021
The quantification of blood flow velocity in the human conjunctiva is clinically essential for assessing microvascular hemodynamics. Since the conjunctival microvessel is imaged in several seconds, eye motion during image acquisition causes motion artifacts limiting the accuracy of image segmentation performance and measurement of the blood flow velocity. In this paper, we introduce a novel customized optical imaging system for human conjunctiva with deep learning-based segmentation and motion correction. The image segmentation process is performed by the Attention-UNet structure to achieve high-performance segmentation results in conjunctiva images with motion blur. Motion correction processes with two steps—registration and template matching—are used to correct for large displacements and fine movements. The image displacement values decrease to 4–7 μm during registration (first step) and less than 1 μm during template matching (second step). With the corrected images, the blood flow velocity is calculated for selected vessels considering temporal signal variances and vessel lengths. These methods for resolving motion artifacts contribute insights into studies quantifying the hemodynamics of the conjunctiva, as well as other tissues.
Journal Article
Bioinspired electronics for intelligent soft robots
2024
Soft robots, capable of safe interaction with delicate objects through their flexibility and compliance, are attracting attention in various real-world applications as manipulators, biomedical devices and wearable tools. As these technologies advance, the ability to perform complex tasks in a robust and reliable way becomes essential. Thus, the incorporation of embedded intelligence in soft robots, which enables them to perceive external environments and generate appropriate actions, is increasingly important. Inspiration from sophisticated biological systems, which exhibit optimized behaviours through the acquisition of external information, promotes the development of intelligent soft robots. Here, we introduce biomimicry strategies for intelligent soft robotics and highlight progress in how soft robots interact with their environment and perform tasks. First, we discuss sensors inspired by the sensory nervous systems and soft actuators inspired by the musculoskeletal systems. Furthermore, we investigate various applications such as manipulation, exploration, wearable devices, biomedical devices and imperceptible devices. We conclude discussing the challenges and offering a perspective on the future direction of this field.Soft robots are evolving to perform increasingly complex tasks, with biomimicry having a fundamental role in their development. This Review details biomimetic strategies and pivotal advances in sensors, actuators and applications of intelligent soft robotics.
Journal Article
High-Frequency Vibrating Stimuli Using the Low-Cost Coin-Type Motors for SSSEP-Based BCI
by
Kim, Hyungmin
,
Jeong, Ji Hyeok
,
Kim, Keun-Tae
in
Algorithms
,
Attention
,
Brain-Computer Interfaces
2022
Steady-state somatosensory-evoked potential- (SSSEP-) based brain-computer interfaces (BCIs) have been applied for assisting people with physical disabilities since it does not require gaze fixation or long-time training. Despite the advancement of various noninvasive electroencephalogram- (EEG-) based BCI paradigms, researches on SSSEP with the various frequency range and related classification algorithms are relatively unsettled. In this study, we investigated the feasibility of classifying the SSSEP within high-frequency vibration stimuli induced by a versatile coin-type eccentric rotating mass (ERM) motor. Seven healthy subjects performed selective attention (SA) tasks with vibration stimuli attached to the left and right index fingers. Three EEG feature extraction methods, followed by a support vector machine (SVM) classifier, have been tested: common spatial pattern (CSP), filter-bank CSP (FBCSP), and mutual information-based best individual feature (MIBIF) selection after the FBCSP. Consequently, the FBCSP showed the highest performance at 71.5±2.5% for classifying the left and right-hand SA tasks than the other two methods (i.e., CSP and FBCSP-MIBIF). Based on our findings and approach, the high-frequency vibration stimuli using low-cost coin motors with the FBCSP-based feature selection can be potentially applied to developing practical SSSEP-based BCI systems.
Journal Article