Publications by authors named "Hyunok Cho"

Cyberattack is one of the severe threats in the digital world as it encompasses everything related to personal information, health, finances, intellectual properties, and even national security. Password-based authentication is the most practiced authentication system, however, is vulnerable to several attacks such as dictionary attack, shoulder surfing attack, and guessing attack. Here, a new keystroke dynamics-based hybrid nanogenerator for biometric authentication and identification integrated with artificial intelligence (AI) is reported.

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Understanding of the triboelectric charge accumulation from the view of microcapacitor formation plays a critical role in boosting the output performance of the triboelectric nanogenerator (TENG). Here, an electrospun nanofiber-based TENG (EN-TENG) using a poly(vinylidene fluoride-trifluoroethylene) (PVDF-TrFE)/MXene nanocomposite material with superior dielectric constant and high surface charge density is reported. The influence of dielectric properties on the output performance of the EN-TENG is investigated theoretically and experimentally.

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Energy harvesting from human-body-induced motion is mostly challenging due to the low-frequency, high-amplitude nature of the motion, which makes the use of conventional cantilevered spring-mass oscillators unrealizable. Frequency up-conversion by mechanical impact is an effective way to overcome the challenge. However, direct impact on the transducer element (especially, piezoelectric) increases the risk of damaging it and raises questions on the reliability of the energy harvester.

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A piezoelectric vibration energy harvester with interdigital shaped cantilever was developed by using silicon bulk micromachining technology. The proposed energy harvester was designed to obtain multi degree-of-freedom (m-DOF). Most of the piezoelectric vibration energy harvesters are comprised of mass-loaded cantilever beams having several resonant frequencies.

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Background And Objectives: Coronary lesions with mismatched functional and anatomical significance are not uncommon. We assessed the accuracy and predictors of mismatch between fractional flow reserve (FFR) and quantitative coronary angiography (QCA) analyses in patients with coronary lesions.

Subjects And Methods: A total of 643 lesions with pre-interventional FFR and QCA measurements were consecutively enrolled and divided into four groups using FFR ≤0.

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Background/aims: While drug-eluting stents (DESs) have shown favorable outcomes in ST-segment elevation myocardial infarction (STEMI) compared to bare metal stents (BMSs), there are concerns about the risk of stent thrombosis (ST) with DESs. Because intravascular ultrasound (IVUS) guidance may help optimize stent placement and improve outcomes in percutaneous coronary intervention (PCI) patients, we evaluated the impact of IVUS-guided BMS versus DES implantation on long-term outcomes in primary PCI.

Methods: In all, 239 STEMI patients received DES (n = 172) or BMS (n = 67) under IVUS guidance in primary PCI.

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Background: Fever is a common finding after primary percutaneous coronary intervention (PPCI) in patients with ST-segment elevation myocardial infarction (STEMI). However, its prognostic value is not validated yet.

Objectives: This study sought to evaluate the impact of fever after PPCI in STEMI on adverse clinical outcomes.

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Background And Objectives: The risk of contrast-induced nephropathy (CIN) is significantly influenced by baseline renal function and the amount of contrast media (CM). We evaluated the usefulness of the cystatin C (CyC) based estimated glomerular filtration rate (eGFRCyC) in the prediction of CIN and to determine the safe CM dosage.

Subjects And Methods: We prospectively enrolled a total of 723 patients who received percutaneous coronary intervention (PCI) and investigated the clinical factors associated with the development of CIN.

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Background And Objectives: Anticoagulation with vitamin K antagonists (VKAs) such as warfarin provides effective stroke prophylaxis in patients with atrial fibrillation (AF). We conducted a large multicenter survey of Korean patients with AF to determine trends in VKA use.

Subjects And Methods: Eligible patients were adults with AF that had been prescribed VKAs.

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Hypertension is an important contributor to different left ventricular (LV) geometric patterns with resultant myocardial dysfunction. Strain rate image (SRI) has been suggested as a useful tool for the evaluation of myocardial function. The aim of this study was to assess whether SRI correlates with LV geometric patterns in hypertensive subjects.

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