Publications by authors named "Sunje Kim"

The quantum valley Hall effect (QVHE) is characterized by the valley Chern number (VCN) in a way that one-dimensional (1D) chiral metallic states are guaranteed to appear at the domain walls (DW) between two domains with opposite VCN for a given valley. Although in the case of QVHE, the total Berry curvature (BC) of the system is zero, the BC distributed locally around each valley makes the VCN well defined as long as intervalley scattering is negligible. Here, we propose a new type of valley-dependent topological phenomenon that occurs when the BC is strictly zero at each momentum.

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In this paper, a novel thermo-optic metagrating based on phase-change material (vanadium dioxide, VO) is proposed for broadband, polarization-independent, and non-dispersive transmission modulation at the telecommunication wavelengths. In the pursuit of concurrent attainment of multiple performance objectives, nanostructured VO metagratings are optimized numerically using inverse design algorithms. Notably, adjoint optimization pertaining to both phases of VO facilitates better modulation capabilities within free-form shaped VO metagratings compared to shape-optimized methods with predetermined designs.

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The free flap is a versatile option for reconstruction of soft tissue defects around the ankle. In patients with poor lower leg circulation, arterial insufficiency is one of the complications that can occur immediately after vessel anastomosis during free flap surgery. The authors were able to improve blood circulation in the flap by using modified turbocharging method in which another perforator was anastomosed to the distal end of the main pedicle.

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Introduction: Radiation therapy, a standard postoperative treatment for breast cancer, can lead to chronic ulcers owing to compromised tissue healing. Accordingly, flap surgery using healthy tissues is essential for aesthetic and functional recovery. Although various flap techniques exist, each has its own drawbacks.

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Background: Despite the increasing popularity of various materials for ischemia-reperfusion (I/R) injury mitigation, research on botulinum toxin type A (BoNTA) remains limited. This study assesses BoNTA's efficacy in protecting flaps from I/R injury by inhibiting the nicotinamide adenine dinucleotide phosphate (NADPH) oxidase system and reducing reactive oxygen species (ROS) production.

Methods: Seventy-six Sprague-Dawley rats were studied.

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Background: A lower eyelid defect is a loss of skin, muscle, and underlying structures that can occur due to trauma, malignant or benign tumors, burns, or other causes. The conventional surgical treatment of lower lid defects has several limitations, including visible scarring, narrowing of the eye, and ectropion. Here, we combined the use of a customized mid-face lift with a free mucochondral graft to overcome the disadvantages of existing methods.

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Marginal reflex distance1 (MRD1) is a crucial clinical tool used to evaluate the position of the eyelid margin in relation to the cornea. Traditionally, this assessment has been conducted manually by plastic surgeons, ophthalmologists, or trained technicians. However, with the advancements in artificial intelligence (AI) technology, there is a growing interest in the development of automated systems capable of accurately measuring MRD1.

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A theoretical approach for reducing multiple monochromatic aberrations using a flat metalens doublet is proposed and verified through ray tracing simulations. The theoretical relation between the Abbe sine condition and the generalized Snell's law is revealed in the doublet system. Starting from the Abbe aplanat design, minimization conditions of astigmatism and field curvature are derived.

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The accurate assessment of wound size is a critical step in advanced wound care management. This study aims to introduce and validate a Light Detection and Ranging (LiDAR) technique for measuring wound size. Twenty-eight wounds treated from December 2022 to April 2023 at the Chungnam National University Hospital were analyzed.

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Background: Despite the increasing popularity of various materials for ischemia-reperfusion (I/R) injury mitigation, research on botulinum toxin type A (BoNTA) remains limited. This study assesses BoNTA's efficacy in protecting flaps from I/R injury by inhibiting the nicotinamide adenine dinucleotide phosphate (NADPH) oxidase system and reducing reactive oxygen species (ROS) production.

Methods: Seventy-six Sprague-Dawley rats were studied.

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Square-shaped and large moon-shaped faces are commonly observed in Asians, and the contour of the mandible is associated with the shape of the lower part of the face. Mandible contouring surgery is performed to create a softer impression for East Asians. Currently, most surgeries are performed using an intraoral approach.

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A gastrocnemius muscle flap is a versatile option for covering the proximal one-third of the lower leg and around the knee. On the other hand, it is of limited use in patients with short gastrocnemius muscle or insufficient volume. The authors present a case in which a knee soft tissue defect occurred in a very thin patient and was reconstructed using a gastrocnemius myocutaneous flap and a distally based gracilis flap as a supplementary flap.

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Many various types of operative techniques have been performed used to treat make-up for sacral defects. Perforator-based flaps with flap transposition, but achieving an optimal flap design and tension-free flap closure without skeletonizing the perforator requires a great deal of clinical experience. In this study, we demonstrate perforator selection based on considerations of the relaxed skin tension line (RSTL), which has proven to be a suitable method of achieving an efficient flap design that enables primary closure.

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Colorimetric sensing, which provides effective detection of bio-molecular signals with one's naked eye, is an exceptionally promising sensing technique in that it enables convenient detection and simplification of entire sensing system. Though colorimetric sensors based on all-dielectric nanostructures have potential to exhibit distinct color variations enabling manageable detection due to their trivial intrinsic loss, there is crucial limitation that the sensitivity to environmental changes lags behind their plasmonic counterparts because of relatively small region of near field-analyte interaction of the dielectric Mie-type resonator. To overcome this challenge, we proposed all-dielectric metasurface colorimetric sensor which exhibits dual-resonance in the visible region.

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In the field of plastic surgery, various filler types have been developed, which are widely used for cosmetic or reconstruction purposes. However, unregulated substances often injected by unlicensed practitioners may cause difficult-to-treat side effects, such as foreign body granulomas. Since the forehead is an exposed area and the lesions are likely extensive, complete surgical removal with inconspicuous scar can be difficult.

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Keloids are a common form of pathologic wound healing and are characterized by an excessive production of extracellular matrix. This study examined the major contributing mechanism of human keloid pathogenesis using transcriptomic analysis. We identified the upregulation of mitochondrial oxidative stress response, protein processing in the endoplasmic reticulum, and TGF-β signaling in human keloid tissue samples compared to controls, based on ingenuity pathway and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses.

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Recently, optical dielectric metasurfaces, ultrathin optical skins with densely arranged dielectric nanoantennas, have arisen as next-generation technologies with merits for miniaturization and functional improvement of conventional optical components. In particular, dielectric metalenses capable of optical focusing and imaging have attracted enormous attention from academic and industrial communities of optics. They can offer cutting-edge lensing functions owing to arbitrary wavefront encoding, polarization tunability, high efficiency, large diffraction angle, strong dispersion, and novel ultracompact integration methods.

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Background: Due to the anatomical complexity of the deep temporal fascia (DTF), practical guidelines for its safe harvest are lacking. However, since the upper temporal compartment (UTC) contains no vital structures, it may provide safe access for DTF harvest. This study aimed to identify the anatomical structures of the temporal compartment in Asian cadavers and to measure their dimensions to enable safe DTF harvest.

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Background: Polydioxanone (PDS) has been widely used in the medical field over the past 30 years. In the 2000s, PDS plate began to be used for rhinoplasty and septoplasty. However, in Asia PDS plates are not widely used due to lack of awareness and high prices.

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Metalens is one of the most prominent applications among metasurfaces since it gives possibilities to replace the conventional lenses for compactness and multi-functionalities. Recently, many studies have been demonstrated to overcome the aberrations of the metalenses for high performance practical applications. Previous studies have used the methods that control the dispersion of meta-atoms for correcting chromatic aberrations and use doublet platform for correcting monochromatic aberrations.

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Color generation based on strategically designed plasmonic nanostructures is a promising approach for display applications with unprecedented high-resolution. However, it is disadvantageous in that the optical response is fixed once the structure is determined. Therefore, obtaining high modulation depth with reversible optical properties while maintaining its fixed nanostructure is a great challenge in nanophotonics.

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Dynamically reconfigurable nanoscale tuning of visible light properties is one of the ultimate goals both in the academic field of nanophotonics and the optics industry demanding compact and high-resolution display devices. Among various efforts incorporating actively reconfigurable optical materials into metamaterial structures, phase-change materials have been in the spotlight owing to their optical tunability in wide spectral regions including the visible spectrum. However, reconfigurable modulation of visible light intensity has been limited with small modulation depth, reflective schemes, and a lack of profound theoretical background for universal design rules.

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Nano-structural colour pixels have attracted much attention as promising solutions for compact display devices. However, it is difficult to miniaturize and integrate conventional transmissive colour filtering components for high resolution pixels within subwavelength scale without sacrificing colour depth. Here, we propose a novel colour pixel structure using bi-layered hybrid metasurfaces that are composed of aluminum nanograting and amorphous silicon nanorod layers.

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Background: The mental V-Y advancement flap method is useful for reconstruction of lower lip defect because of its many advantages. However, it is not easy to select the optimal reconstructive method for the vermilion defect that remains after application of the mental V-Y advancement flap. In choosing the representative surgical method for vermilion mucosal reconstruction including mucosal V-Y advancement flap, buccal mucosal flap, and buccal mucosal graft.

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