Publications by authors named "DooWon Lee"

Article Synopsis
  • - The paper discusses the optimization of IGZO/Ag/IGZO (IAI) multilayer films using post-rapid thermal annealing (RTA) to improve their electrical conductivity and optical transmittance for solar cells.
  • - The optimized films achieved an average optical transmittance of 85% in visible light and a low sheet resistance of 6.03 Ω/□ after being annealed at 500 °C for 60 seconds.
  • - Testing with a solar cell simulator revealed a high photo-generated short circuit current density of 40.73 mA/cm, indicating that the IAI multilayer films are effective as transparent electrodes in solar cell applications.
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We present a transparent memristor with a rough-surface (RS) bottom electrode (BE) with enhanced performance and reliability for a gasistor, which is a gas sensor plus a memristor, and its application in this paper. The transparent memristor, with an RS BE, exhibited low forming voltages (0.8 V) and a stable resistive switching behavior, with high endurance and an on/off ratio of about 125.

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Low-power-consumption gas sensors are crucial for diverse applications, including environmental monitoring and portable Internet of Things (IoT) systems. However, the desorption and adsorption characteristics of conventional metal oxide-based gas sensors require supplementary equipment, such as heaters, which is not optimal for low-power IoT monitoring systems. Memristor-based sensors (gasistors) have been investigated as innovative gas sensors owing to their advantages, including high response, low power consumption, and room-temperature (RT) operation.

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In aerospace applications, SiO deposition on perovskite solar cells makes them more stable. However, the reflectance of the light changes and the current density decreases can lower the efficiency of the solar cell. The thickness of the perovskite material, ETL, and HTL must be re-optimized, and testing the number of cases experimentally takes a long time and costs a lot of money.

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BN-based resistive random-access memory (RRAM) has emerged as a potential candidate for non-volatile memory (NVM) in aerospace applications, offering high thermal conductivity, excellent mechanical, and chemical stability, low power consumption, high density, and reliability. However, the presence of defects and trap states in BN-based RRAM can limit its performance and reliability in aerospace applications. As a result, higher set voltages of 1.

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Antireflection coatings (ARCs) with an indium thin oxide (ITO) layer on silicon heterojunction solar cells (SHJ) have garnered significant attention, which is due to their potential for increasing current density (J) and enhancing reliability. We propose an additional tungsten trioxide (WO) layer on the ITO/Si structure in this paper in order to raise the J and demonstrate the influence on the SHJ solar cell. First, we simulate the J characteristics for the proposed WO/ITO/Si structure in order to analyze J depending on the thickness of WO using an OPAL 2 simulator.

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Memristor-based gas sensors (gasistors) have been considered as the most promising candidate for detecting NO gas suitable for neural network (NN) analysis. In this work, in order to solve an overfitting issue arising from the training data when using a single gasistor, which degrades the accuracy of NN, we here propose a metal-insulator-silicon (MIS)-structured ZrN-based gasistor array that results in an improvement in both the accuracy of the NN analysis and the efficiency of the operating power. As a result, the proposed gasistor array showed a decrease of epoch and a 2.

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Oxygen (O) sensing in trace amounts and mixed gas is essential in many types of industries. Semiconductor sensors have proven to be invaluable tools for the O measurements in a wide concentration range, but the sensors are only able to quantify O in a concentration range of subppm, thus far, especially in mixed gas. We present in this paper a new concept for O sensing with incomparable sensitivity using IGZO-films with oxygen vacancy-based conducting filaments (CFs).

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We examine the connection between firm performance and a CEO's previous position (inside or outside the firm), using Covid-19 as an exogenous shock. Firms led by insider CEOs outperformed those led by outsider CEOs in terms of return on assets during the Covid-19 crisis period in 2020, but there was no performance differential in the period before the crisis. Additional tests indicate that outperformance under insider CEOs is observed in firms holding more cash and firms with a higher proportion of internally promoted non-CEO executives.

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Fast recovery, high sensitivity, high selectivity, and room temperature (RT) sensing characteristics of NO gas sensors are essential for environmental monitoring, artificial intelligence, and inflammatory diagnosis of asthma patients. However, the conventional semiconductor-type gas sensors have poor sensing characteristics that need to be solved, such as slow recovery speeds (>360 s), low sensitivity (3.8), and high operating temperatures (>300 °C).

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This study aimed to evaluate the effects of warm-up intensity on energetic contribution and performance during a 100-m sprint. Ten young male sprinters performed 100-m sprints following both a high-intensity warm-up (HIW) and a low-intensity warm-up (LIW). Both the HIW and LIW were included in common baseline warm-ups and interventional warm-ups (eight 60-m runs, HIW; 60 to 95%, LIW; 40% alone).

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Exercise is recommended to increase physical health and performance. However, it is unclear how low-intensity exercise (LIE) of different durations may affect or improve recovery ability. This study aimed to investigate how LIE-duration with the same volume affects recovery ability in adults.

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Objectives: To describe how health care crisis resulting from the COVID-19 pandemic in South Korea has led to innovation and changes to government policy. This paper presents the significant cluster events, relevant developments of innovation, and economical impact in Korea that could inform policy makers on how to respond to health crises in the future.

Methods: Health care, economy, epidemiological data are collected from various sources including the Korea Centers for Disease Control and Prevention (KCDC) or other government sources.

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Exergames have been recommended as alternative ways to increase the health benefits of physical exercise. However, energy system contributions (phosphagen, glycolytic, and oxidative) of exergames in specific age groups remain unclear. The purpose of this study was to investigate the contributions of three energy systems and metabolic profiles in specific age groups during exergames.

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Copper plating has been considered as a future metallization technique to reduce metal contact area and material cost in silicon heterojunction (SHJ) solar cells. In this paper, a Cu-Sn alloy film is used as a seed layer material on an indium tin oxide (ITO) layer with the goal to enhance contact resistivity between the seed and ITO layer. The contact resistivity between the seed layer and ITO is an important parameter because low contact resistivity is required for the high fill factor of the solar cells.

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The realization of a high-throughput biosensor platform with ultrarapid detection of biomolecular interactions and an ultralow limit of detection in the femtomolar (fM) range or below has been retarded due to sluggish binding kinetics caused by the scarcity of probe molecules on the nanostructures and/or limited mass transport. Here, as a new method for the highly efficient capture of biomolecules at extremely low concentration, we tested a three-dimensional (3D) platform of a bioelectronic field-effect transistor (bio-FET) with vertically aligned and highly dense one-dimensional (1D) ZnO nanorods (NRs) as a sensing surface capped by an ultrathin TiO2 layer for improved electrolytic stability on a chemical-vapor-deposited graphene (Gr) channel. The ultrarapid detection capability with a very fast response time (∼1 min) at the fM level of proteins in the proposed 3D bio-FET is primarily attributed to the fast binding kinetics of the probe-target proteins due to the small diffusion length of the target molecules to reach the sensor surface and the substantial number of probe molecules available on the largely increased surface area of the vertical ZnO NRs.

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Ultraviolet (UV) photodetectors based on ZnO nanostructure/graphene (Gr) hybrid-channel field-effect transistors (FETs) are investigated under illumination at various incident photon intensities and wavelengths. The time-dependent behaviors of hybrid-channel FETs reveal a high sensitivity and selectivity toward the near-UV region at the wavelength of 365 nm. The devices can operate at low voltage and show excellent selectivity, high responsivity (RI ), and high photoconductive gain (G).

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The open-reading frame PF0895 in the genome of the hyperthermophilic archaeon, Pyrococcus furiosus, encodes a 206-residue protein (M(R )23,152). The structure of the recombinant protein was solved by single isomorphous replacement with anomalous scattering (SIRAS) using a mercury derivative. It has been refined to 1.

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The hypothetical protein PF0899 is a 95-residue peptide from the hyperthermophilic archaeon Pyrococcus furiosus that represents a gene family with six members. P. furiosus ORF PF0899 has been cloned, expressed and crystallized and its structure has been determined by the Southeast Collaboratory for Structural Genomics (http://www.

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The strict anaerobic, thermophilic bacterium Moorella thermoacetica metabolizes C1 compounds for example CO(2)/H(2), CO, formate, and methanol into acetate via the Wood/Ljungdahl pathway. Some of the key steps in this pathway include the metabolism of the C1 compounds into the methyl group of methylenetetrahydrofolate (MTHF) and the transfer of the methyl group from MTHF to the methyl group of acetyl-CoA catalyzed by methyltransferase, corrinoid protein and CO dehydrogenase/acetyl CoA synthase. Recently, we reported the crystallization of a 25 kDa methanol-induced corrinoid protein from M.

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A corrinoid protein was induced and overexpressed in methanol-grown cells of the thermophilic anaerobic bacterium Moorella thermoacetica. The protein was purified from cytosolic extracts. After screening for crystallization conditions and optimization, crystals were obtained that diffracted strongly on a rotating-anode X-ray source.

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Proteins derived from the coding regions of Pyrococcus furiosus are targets for three-dimensional X-ray and NMR structure determination by the Southeast Collaboratory for Structural Genomics (SECSG). Of the 2,200 open reading frames (ORFs) in this organism, 220 protein targets were cloned and expressed in a high-throughput (HT) recombinant system for crystallographic studies. However, only 96 of the expressed proteins could be crystallized and, of these, only 15 have led to structures.

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The first X-ray crystal structure of a non-natural dinucleotide, 5'-O-phosphoryl-1'-deoxy-2'-isoadenylyl-(3' --> 5')-cytidine 6.5-hydrate (pIsodApC), C19H26N8O13P2 x 6.5H2O, belonging to a family of dinucleotides that contain an isomeric nucleoside component, is described.

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Article Synopsis
  • High-throughput macromolecular crystallography has seen advancements in phasing methods, notably through single-wavelength anomalous scattering (SAS) using chromium X-ray radiation, allowing successful protein structure determination with weak scatterers like sulfur.
  • Combining selenomethionine-derivatized proteins with chromium radiation enhances the phasing process due to selenium's stronger scattering capability.
  • The study successfully determined the crystal structure of a chorismate mutase from Clostridium thermocellum using this method, achieving quick structure solution and refinement, suggesting it could become a standard for in-house crystallography.
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