Publications by authors named "Han-Ki Kim"

Article Synopsis
  • Gastroesophageal Reflux Disease (GERD) leads to stomach contents flowing back into the esophagus, which may also affect ear health through the Eustachian tube.
  • A study of over 669,000 South Korean patients found a strong link between GERD and the occurrence of tinnitus, suggesting that the ear issues could be related to reflux problems.
  • However, treating GERD with proton pump inhibitors did not significantly lower the chances of developing tinnitus in these patients.*
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2D transition-metal dichalcogenides are emerging as key materials for next-generation semiconductor technologies owing to their tunable bandgaps, high carrier mobilities, and exceptional surface-to-volume ratios. Among them, molybdenum disulfide (MoS) has garnered significant attention. However, scalable wafer-level deposition methods that enable uniform layer-controlled synthesis remain a critical challenge.

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Background: Acute ischemic stroke (AIS) remains a major cause of morbidity and mortality worldwide. Mechanical thrombectomy, especially with stent retrievers, offers a promising treatment, particularly for patients ineligible for intravenous tissue plasminogen activator (IV tPA) therapy. This study aimed to develop and evaluate novel stent retriever designs to enhance mechanical properties and vessel compatibility.

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High-performance flexible Sn-doped InO (indium tin oxide, ITO) electrodes were fabricated using a multicoating process on colorless polyimide (CPI) substrates for flexible perovskite solar cells (FPSCs). The effects of different coating sequences on the electrical, optical, and mechanical properties of the flexible ITO electrodes were thoroughly investigated after preparing them with direct-current magnetron sputtering (DMS) and arc plasma ion plating (APIP). Although both the sputtered ITO (SITO)/arc ion-plated ITO (AITO) film and the AITO/SITO film showed similarly low sheet resistance (18.

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We integrated transparent antireflective coatings and transparent electrodes onto flexible colorless polyimide (CPI) substrates to fabricate high-performance flexible perovskite solar cells. Multifunctional PPFC/CPI/IGTO substrates were fabricated by sputtering the optimal plasma-polymerized fluorocarbon (PPFC) antireflective coating and InGaTiO (IGTO) electrode films on both sides of the CPI substrate. By applying PPFC with a low refractive index (1.

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In colloidal quantum dot light-emitting diodes (QD-LEDs), replacing organic hole transport layers (HTLs) with their inorganic counterparts is expected to yield distinct advantages due to their inherent material robustness. However, despite the promising characteristics of all-inorganic QD-LEDs, some challenges persist in achieving stable operation; for example, the electron overflow toward the inorganic HTL and charge accumulation within working devices return a temporal inconsistency in device characteristics. To address these challenges, we propose an operational approach that employs an alternating-current (AC) in all-inorganic QD-LEDs.

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Perovskite solar cells (PSCs) exhibit sufficient technological efficiency and economic competitiveness. However, their poor stability and scalability are crucial factors limiting their rapid development. Therefore, achieving both high efficiency and good stability is an urgent challenge.

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Article Synopsis
  • - This study investigates how colorectal cancer progresses, particularly the shift towards more aggressive, metastatic behavior as tumors invade surrounding tissues.
  • - It defines "evolution" as the transition from structured tumor formations to invasive cancer cell growth, focusing on cancer cell buddings at the invasive front.
  • - The research identifies two types of senescent tumor cells (Type I and Type II) that contribute differently to cancer progression, with Type II being significant for local invasion and lymph node metastasis, which may influence patient outcomes.
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Background: Mechanical thrombectomy is an effective treatment method for large-vessel occlusion stroke (LVOS); however, it has limited efficacy for intracranial atherosclerotic disease (ICAD)-related LVOS. We investigated the use of cerebral blood volume (CBV) maps for identifying ICAD as the underlying cause of LVOS before the initiation of endovascular treatment (EVT).

Methods And Results: We reviewed clinical and imaging data from patients who presented with LVOS and underwent endovascular treatment between January 2011 and May 2021.

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In this study, we incorporated TiN as a carrier suppressor into an amorphous InZnO channel to achieve stable channels for thin-film transistors (TFTs) and light-emitting transistors (LETs). The low electronegativity and standard electrode potential of the Ti dopant led to a reduction in the number of oxygen vacancies in the InZnO channel. Moreover, the substitution of nitrogen into the oxygen sites of InZnO effectively decreased the excess electrons.

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Background: Biodegradable poly (l-lactic acid) (PLLA), a bio safe polymer with a large elastic modulus, is widely used in biodegradable medical devices. However, because of its poor mechanical properties, a PLLA strut must be made twice as thick as a metal strut for adequate blood vessel support. Therefore, the mechanical properties of a drug-eluting metal-based stents (MBS) and a bioresorbable vascular scaffolds (BVS) were evaluated and their safety and efficacy were examined via a long-term rabbit iliac artery model.

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Refractory status epilepticus (RSE) requires multimodal treatment approaches to achieve rapid seizure cessation and neuroprotection. A ketogenic diet (KD) has demonstrated efficacy as a nutritional therapeutic option for adult RSE. However, the group of adult RSE patients who would benefit from adopting a KD needs to be determined to appropriately select the patients indicated for a KD.

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In this study, we demonstrated poly(3,4-ethylenedioxythiophene): poly(styrene sulfonate) (PEDOT:PSS) as a composite with Ag nanowire (Ag NW) to enhance the stretchability of the Ag NW network electrode. The composite Ag NW/PEDOT:PSS hybrid ink (AP ink) was prepared at a ratio of 1 : 10, 1 : 20, and 1 : 30, respectively and bar coated on polyurethane substrate. The different ink ratios were studied and optimized with a sheet resistance of 14.

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We demonstrated highly transparent and flexible polytetrafluoroethylene (PTFE) passivation for the MoS/Ag nanowire (Ag NW) electrodes used in thin film heaters (TFHs). The electrical, optical, and mechanical properties of PTFE coated MoS/Ag NW electrode were compared to the bare MoS/Ag NW electrode to demonstrate effective passivation of the sputtered PTFE films before and after the 85 °C-85% temperature-relative humidity environment test. In addition, we investigated the performances of TFHs with PTFE/MoS/Ag NW as a function of PTFE thickness from 50 to 200 nm.

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The state-of-the-art quantum dot (QD) based light-emitting diodes (QD-LEDs) reach near-unity internal quantum efficiency thanks to organic materials used for efficient hole transportation within the devices. However, toward high-current-density LEDs, such as augmented reality, virtual reality, and head-up display, thermal vulnerability of organic components often results in device instability or breakdown. The adoption of a thermally robust inorganic hole transport layer (HTL), such as NiO, becomes a promising alternative, but the large energy offset between the NiO HTL and the QD emissive layer impedes the efficient operation of QD-LEDs.

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Multi-valued logic gates are demonstrated on solution-processed molybdenum disulfide (MoS) thin films. A simple chemical doping process is added to the conventional transistor fabrication procedure to locally increase the work function of MoS by decreasing sulfur vacancies. The resulting device exhibits pseudo-heterojunctions comprising as-processed MoS and chemically treated MoS (c-MoS).

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Two-dimensional molybdenum disulfide (MoS) nanosheets have emerged as a promising material for transparent, flexible micro-supercapacitors, but their use in electrodes is hindered by their poor electrical conductivity and cycling stability because of restacking. In this paper, we report a novel electrode architecture to exploit electrochemical activity of MoS nanosheets. Electrochemically exfoliated MoS dispersion was spin coated on mesh-like silver networks encapsulated with a flexible conducting film exhibiting a pseudocapacitive behavior.

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We investigated a flexible and transparent conductive electrode (FTCE) based on Ag nanowires (AgNWs) and a graphene oxide (GO) nanosheet and fabricated through a simple and cost-effective spray coating method. The AgNWs/GO hybrid FTCE was optimized by adjusting the nozzle-to-substrate distance, spray speed, compressor pressure, and volume of the GO solution. The optimal AgNWs/GO hybrid FTCE has a high transmittance of 88% at a wavelength of 550 nm and a low sheet resistance of 20 Ohm/square.

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The synthesis of uniform low-defect graphene on a catalytic metal substrate is getting closer to the industrial level. However, its practical application is still challenging due to the lack of an appropriate method for its scalable damage-free transfer to a device substrate. Here, an efficient approach for a defect-free, etchant-free, wrinkle-free, and large-area graphene transfer is demonstrated by exploiting a multifunctional viscoelastic polymer gel as a simultaneous shock-free adhesive and dopant layer.

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In order to ensure high-performance semitransparent perovskite solar cells (ST-PSCs), the deposition of high-quality scalable transparent cathodes on ST-PSCs at room temperature is necessary. In this study, we designed an amorphous InGaTiO (IGTO) electrode, prepared by linear facing target sputtering (LFTS) as a transparent cathode for ST-PSCs. Even in the room temperature sputtering process, the amorphous IGTO cathode showed a low sheet resistance of 9.

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We fabricated transparent and flexible silicon oxycarbide (SiOC) hard coating (HC) films on a colorless polyimide substrate to use as cover window films for flexible and foldable displays using a reactive roll-to-roll (R2R) sputtering system at room temperature. At a SiOC thickness of 100 nm, the R2R-sputtered SiOC film showed a high optical transmittance of 87.43% at a visible range of 400 to 800 nm.

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We investigated simple and unrestricted brush-paintable black electrodes for poly(vinylidene fluoride) (PVDF)-based artistic flexible piezoelectric devices. The conductive black ink for paintable electrodes was synthesized by mixing poly(3,4-ethylene dioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) and typical black ink and optimizing the mixing ratio. At an optimal mixing ratio, the brush-paintable black electrodes showed a sheet resistance of 151 Ω/sq and high coatability for flexible piezoelectric devices.

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With rapid advances in flexible electronics, transparent conductive electrodes (TCEs) have also been significantly developed as alternatives to the conventional indium tin oxide (ITO)-based material systems that exhibit low mechanical flexibility. Nanomaterial-based alternating materials, such as graphene, nanowire, and nanomesh, exhibit remarkable properties for TCE-based applications, such as high electrical conductivity, high optical transparency, and high mechanical stability. However, these nanomaterial-based systems lack scalability, which is a key requirement for practical applications, and exhibit a size-dependent property variation and inhomogeneous surface uniformity that limit reliable properties over a large area.

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We compared nickel oxide (NiO ) deposited by thermal evaporation and that deposited by the spin-coating process, for use in the hole transport layers of inverted planar perovskite solar cells (PSCs). Spin-coating deposition for NiO HTL has been widely used, owing to its simplicity, low cost, and high efficiency. However, the spin-coating process has a technical limit to depositing a large-area uniformly.

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We investigated the characteristics of thermally evaporated fullerene (C)/Ag/C (CAC) multilayer films for use in semi-transparent perovskite solar cells (PSCs) and thin-film heaters (TFHs). The top and bottom C layers and Ag interlayer were prepared using multi-source thermal evaporation, and the thickness of the Ag interlayer was investigated in detail for its effects on the resistivity, optical transmittance, and mechanical properties of the CAC electrodes. We used a figure-of-merit analysis to obtain a CAC electrode with a smooth surface morphology that exhibited a sheet resistance of 5.

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