Publications by authors named "Junhyeok Choi"

Purpose: To examine the discrepancy in breast density assessments by radiologists, LIBRA software, and AI algorithm and their association with breast cancer risk.

Methods: Among 74,610 Korean women aged ≥ 34 years, who underwent screening mammography, density estimates obtained from both LIBRA and the AI algorithm were compared to radiologists using BI-RADS density categories (A-D, designating C and D as dense breasts). The breast cancer risks were compared according to concordant or discordant dense breasts identified by radiologists, LIBRA, and AI.

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Article Synopsis
  • * The research indicates that while high-k passivation materials increased breakdown voltage by up to 17.45%, they also raised parasitic capacitances, which lowered the transistors' cut-off frequency.
  • * Ultimately, the HfO partial passivation structure was identified as an optimal choice for high-power and high-frequency applications due to its balance of lower breakdown voltage loss and significant improvement in cut-off frequency.
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Background CT performed for various clinical indications has the potential to predict cardiometabolic diseases. However, the predictive ability of individual CT parameters remains underexplored. Purpose To evaluate the ability of automated CT-derived markers to predict diabetes and associated cardiometabolic comorbidities.

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Background: Artificial intelligence (AI) algorithms for the independent assessment of screening mammograms have not been well established in a large screening cohort of Asian women. We compared the performance of screening digital mammography considering breast density, between radiologists and AI standalone detection among Korean women.

Methods: We retrospectively included 89,855 Korean women who underwent their initial screening digital mammography from 2009 to 2020.

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In this study, we propose an optimized AlGaN/GaN high-electron-mobility transistor (HEMT) with a considerably improved breakdown voltage. First, we matched the simulated data obtained from a basic T-gate HEMT with the measured data obtained from the fabricated device to ensure the reliability of the simulation. Thereafter, to improve the breakdown voltage, we suggested applying a gate-head extended structure.

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() is a causal agent of watermelon bacterial fruit blotch (BFB) disease. Because resistance cultivars/lines have not yet been developed, it is imperative to elucidate 's virulence factors and their mechanisms to develop resistant cultivars/lines in different crops, including watermelon. The glucose-6-phosphate isomerase (GPI) is a reversible enzyme in both glycolysis and gluconeogenesis pathways in living organisms.

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Aims: Mammography, commonly used for breast cancer screening in women, can also predict cardiovascular disease. We developed mammography-based deep learning models for predicting coronary artery calcium (CAC) scores, an established predictor of coronary events.

Methods And Results: We evaluated a subset of Korean adults who underwent image mammography and CAC computed tomography and randomly selected approximately 80% of the participants as the training dataset, used to develop a convolutional neural network (CNN) to predict detectable CAC.

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The meta-reinforcement learning (meta-RL) framework, which involves RL over multiple timescales, has been successful in training deep RL models that generalize to new environments. It has been hypothesized that the prefrontal cortex may mediate meta-RL in the brain, but the evidence is scarce. Here we show that the orbitofrontal cortex (OFC) mediates meta-RL.

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A comprehensive understanding of neuronal diversity and connectivity is essential for understanding the anatomical and cellular mechanisms that underlie functional contributions. With the advent of single-cell analysis, growing information regarding molecular profiles leads to the identification of more heterogeneous cell types. Therefore, the need for additional orthogonal recombinase systems is increasingly apparent, as heterogeneous tissues can be further partitioned into increasing numbers of specific cell types defined by multiple features.

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Owing to the increasing demand for the miniaturization and integration of electronic devices, thermal interface materials (TIMs) are crucial components for removing heat and improving the lifetime and safety of electronic devices. Among these, thermal pads are reusable alternatives to thermal paste-type TIMs; however, conventional thermal pads comprise a homogeneous polymer with low thermal conductivity. Composite materials of thermally conducting fillers and polymer matrices are considered suitable alternatives to high-performance pad materials owing to their controllable thermal properties.

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This study investigates the operating characteristics of AlGaN/GaN high-electron-mobility transistors (HEMTs) by applying HfO as the passivation layer. Before analyzing HEMTs with various passivation structures, modeling parameters were derived from the measured data of fabricated HEMT with SiN passivation to ensure the reliability of the simulation. Subsequently, we proposed new structures by dividing the single SiN passivation into a bilayer (first and second) and applying HfO to the bilayer and first passivation layer only.

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Acidovorax citrulli (Ac) is a phytopathogenic bacterium that causes bacterial fruit blotch (BFB) in cucurbit crops, including watermelon. However, there are no effective methods to control this disease. YggS family pyridoxal phosphate-dependent enzyme acts as a coenzyme in all transamination reactions, but its function in Ac is poorly understood.

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Objectives: Healthcare workers in hospitals (HHCWs), a notably increasing workforce, face various occupational hazards. A high incidence of cancer among HHCWs has been observed; however, the cancer incidence status among HHCWs in South Korea is yet to be studied. This study aimed to assess cancer incidence among HHCWs in South Korea.

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() is a gram-negative bacterium that causes bacterial fruit blotch (BFB) disease in cucurbit crops including watermelon. However, despite the great economic losses caused by this disease worldwide, -resistant watermelon cultivars have not been developed. Therefore, characterizing the virulence factors/mechanisms of would enable the development of effective control strategies against BFB disease.

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This study investigates the operational characteristics of AlGaN/GaN high-electron-mobility transistors (HEMTs) by applying a slant-gate structure and drain-side extended field-plate (FP) for improved breakdown voltage. Prior to the analysis of slant-gate-based HEMT, simulation parameters were extracted from the measured data of fabricated basic T-gate HEMTs to secure the reliability of the results. We suggest three different types of slant-gate structures that connect the basic T-gate electrode boundary to the 1st and 2nd SiN passivation layers obliquely.

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Green and renewable energy is the key to overcoming energy-related challenges such as fossil-fuel depletion and the worsening of environmental habituation. Among the different clean energy sources, hydrogen is considered the most impactful energy carrier and is touted as an alternate fuel for clean energy needs. Even though noble metal catalysts such as Pt, Pd, and Au exhibit excellent hydrogen evolution reaction (HER) activity in acid media, their earth abundance and capital costs are highly debatable.

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The number of cases and incidence rates of laryngeal and lung cancers have been increasing globally. Therefore, identifying the occupational causes of such cancers is an important concern for policymakers to prevent cancers and deaths. We used national health insurance service claims data in Korea.

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To compare the risk of developing gastrointestinal (GI) cancer according to industrial groups, we performed a retrospective cohort study using the database of the Korea National Health Insurance Service (NHIS). We calculated the age-standardized incidence ratios (SIRs) and 95% confidence intervals (95% CIs) for the types of GI cancers according to the Korean Standard Industrial Classification (KSIC) compared with the whole employee population. The highest SIR for all GI cancer was found in the "Mining and quarrying" section (SIR, 1.

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Erwinia amylovora, the causal agent of fire-blight disease in apple and pear trees, was first isolated in South Korea in 2015. Although numerous studies, including omics analyses, have been conducted on other strains of E. amylovora, studies on South Korean isolates remain limited.

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A single protein can be multifaceted depending on the cellular contexts and interacting molecules. LIN28A is an RNA-binding protein that governs developmental timing, cellular proliferation, differentiation, stem cell pluripotency, and metabolism. In addition to its best-known roles in microRNA biogenesis, diverse molecular roles have been recognized.

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The cortico-basal ganglia-thalamo-cortical loop is one of the fundamental network motifs in the brain. Revealing its structural and functional organization is critical to understanding cognition, sensorimotor behaviour, and the natural history of many neurological and neuropsychiatric disorders. Classically, this network is conceptualized to contain three information channels: motor, limbic and associative.

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Amorphous alloys are being newly applied in wastewater treatment because of their unique atomic packing structure. They possess excellent degradation efficiency, stability and reusability. In this work, FeSiB and FeSiBP amorphous ribbons exhibited advanced catalytic performance for the degradation of Methyl Blue (MB) and Rhodamine B (RhB) dyes, and the color removal reach nearly 100% within 11 min for both the dyes.

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The basal ganglia regulate a wide range of behaviors, including motor control and cognitive functions, and are profoundly affected in Parkinson's disease (PD). However, the functional organization of different basal ganglia nuclei has not been fully elucidated at the circuit level. In this study, we investigated the functional roles of distinct parvalbumin-expressing neuronal populations in the external globus pallidus (GPe-PV) and their contributions to different PD-related behaviors.

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In this work, the enhanced resistive switching of ZrN-based resistive switching memory is demonstrated by embedding TiO layer between Ag top electrode and ZrN switching layer. The Ag/ZrN/n-Si device exhibits unstable resistive switching as a result of the uncontrollable Ag migration. Both unipolar and bipolar resistive switching with high RESET current were observed.

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Synopsis of recent research by authors named "Junhyeok Choi"

  • - JunHyeok Choi's research spans various fields, notably focusing on semiconductor devices, particularly AlGaN/GaN high-electron-mobility transistors (HEMTs), exploring the impact of different dielectric passivation materials on their performance, and optimizing design structures to enhance breakdown voltage for high-power applications.
  • - The author has also investigated the application of automated imaging techniques, including CT and mammography, to predict cardiometabolic conditions and coronary artery calcification, showcasing the potential for AI in enhancing diagnostic accuracy in medical imaging.
  • - Additionally, Choi's exploration of meta-reinforcement learning and its neural underpinnings, along with studies on novel transgene delivery systems for neuronal population targeting, indicates a strong interest in advancing both artificial intelligence and biomedical research methodologies.