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Rewritable, Printable Conducting Liquid Metal Hydrogel
Park, Jung-Eun,Kang, Han Sol,Baek, Jonghyek,Park, Tae Hyun,Oh, Seunghee,Lee, Hyungsuk,Koo, Min,Park, Cheolmin American Chemical Society 2019 ACS NANO Vol.13 No.8
<P>The development of high-performance printable electrical circuits, particularly based on liquid metals, is fundamental for device interconnection in flexible electronics, motivating numerous attempts to develop a variety of alloys and their composites. Despite their great potential, rewritable and printable electronic circuits based on liquid metals are still manufactured on demand. In this study, we demonstrate liquid metal-based hydrogels suitable for rewritable, printable electrical circuits. Our liquid metal hydrogels are based on sedimentation-induced composites of eutectic gallium-indium (EGaIn) particles in poly(ethylene glycol) diacrylate (PEGDA). The EGaIn particles are vertically phase-segregated in the PEGDA. When a composite surface with high EGaIn content is gently scratched, the surface covering PEGDA is removed, followed by the rupture of the native oxide layers of the particles, and the exposed EGaIn becomes conductive. The subsequent water-driven swelling of PEGDA on the scratched surface completely erases the conductive circuit, causing the system to reset. Our friction-responsive liquid metal hydrogel exhibits writing-erasing endurance for 20 cycles, with a dramatic change in the electrical resistance from metal (∼1 Ω) to insulator (∼10<SUP>7</SUP> Ω). By employing surface friction pen printing, we demonstrate mechanically flexible, rewritable, printable electrical conductors suitable for displays.</P> [FIG OMISSION]</BR>
Theory of Two-dimensional Liquid and its Application to Multilayer Physical Absorption
Park, Hyungsuk 서울대학교 교양과정부 1974 論文集 Vol.6 No.-
이차원 액체 분자는 기체와 같은 자유도와 고체와 같은 자유도를 갖는다고 가정하고서 이차원액체 이론을 유도하였다. 이 이론을 기체흡착질이 고체표면에 흡착되는 경우에 적용하여 보았다. 이때 어느 한층의 흡착은 그 아래층의 고체와 같은 자유도를 가진 분자위에만 흡착될 수 있다고 가정하였다. The theory of two-dimensional liquid is presented by assuming the liquid molecules have gas-like and solid-like degrees of freedom. This theory is applied to the multilayer physical adsorption of the gases on the solid adsorbents by assuming the adsorbates are absorbed only on the solid-like molecules.
Han, HyungSuk,Lee, KyungHyun,Park, SungHo,Park, Seonghun,Song, MyongKen Elsevier 2015 Engineering failure analysis Vol.48 No.-
<P><B>Abstract</B></P> <P>In order to protect bolts from corrosion, electroplating such as zinc plating is widely used. However, hydrogen can easily penetrate or diffuse into the vacancies and dislocations between the lattices of bolt steel during electroplating. As the diffused hydrogen defects inside the lattice are in gaseous form, small cracks can easily be produced due to high pressure from the hydrogen gas. In this research, in order to determine the root cause of the fracture in pole fastening screws resulting from hydrogen embrittlement in typical electric motors, additional factors that accelerate hydrogen embrittlement fracture were selectively applied, including a small fillet in the head–shank transition and excessive hardness, and parametric study was performed experimentally.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Fatigue limit of the test bolt is reduced about 8% after zinc electroplating without baking. </LI> <LI> Fatigue limit is reduced about 51% for high hardness bolt with small fillet and without baking. </LI> <LI> Baking time, hardness and fillet can affect the life reduction of bolt with hydrogen embrittlement. </LI> </UL> </P>
Evaluation of acromial spur using ultrasonography
Hyungsuk Kim,Syungkyun Choi,Soo Bin Park,Hyun Seok Song 대한견주관절의학회 2021 대한견주관절의학회지 Vol.24 No.1
Background: The presence of an acromial spur implies a rotator cuff disorder due to impingement between the acromial spur and the rotator cuff. The purpose of the study was to observe acromial spurs using ultrasonography and to compare measurements between plain radiographs and sonograms. Methods: We retrospectively enrolled 51 consecutive patients with acromial spurs, which were interpreted on preoperative plain radiographs (supraspinatus outlet view and 30° caudal tilt) and preoperative sonograms. The ultrasonography transducer was held vertically and continuously moved laterally, which corresponded to the long axis of the long head of the biceps. The distance from the most distal margin of the original acromion to the most projected point of the acromial spur was measured. Results: No significant difference was found between the plain radiograph and ultrasonography measurements (p=0.186). A moderate to strong correlation was detected between the ultrasonography and supraspinatus outlet-view measurements (r=0.776, p=0.000). Conclusions: Anteriorly projected acromial spurs were well-visualized by ultrasonography. No discrepancy in acromial spur length was detected between the use of plain radiography (supraspinatus outlet view and 30° caudal-tilt view) and ultrasonography. The correlation coefficients between the plain radiography and ultrasonography measurements exceeded 0.7.
Determination of the molecular assembly of actin and actin-binding proteins using photoluminescence
Park, Byeongho,Oh, Seunghee,Jo, Seunghan,Kang, Donyoung,Lim, Juhwan,Jung, Youngmo,Lee, Hyungsuk,Jun, Seong Chan Elsevier 2018 Colloids and Surfaces B Vol.169 No.-
<P><B>Abstract</B></P> <P>Actin, the most abundant protein in cells, polymerizes into filaments that play key roles in many cellular dynamics. To understand cell dynamics and functions, it is essential to examine the cytoskeleton structure organized by actin and actin-binding proteins. Here, we pave the way for determining the molecular assembly of the actin cytoskeleton using direct photonic <I>in situ</I> analysis, providing the photoluminescence characteristics of actin as a function of filament length and bundling, without labeling. In experiments for monomeric and filamentous actin reconstituted <I>in vitro</I>, structural forms of actin are identified from the peak positions and intensities of photoluminescence. Actin monomers exhibited small intensity emission peaks at 334 nm, whereas filamentous and bundled actin showed a shifted peak at 323 nm with higher intensity. The peak shift was found to be proportional to the length of the actin filament. With probing structural change of actin in various cells <I>in vivo</I>, our study provides an efficient and precise analytical <I>in situ</I> tool to examine the cytoskeleton structure. It will be beneficial for elucidating the mechanism of various cellular functions such as cell migration, differentiation, cytokinesis and adhesion. Furthermore, our technique can be applied to detect the alterations in the cell cytoskeleton that can occur during many pathological processes.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Modification of actin samples with different structures using binding protein. </LI> <LI> Method for monitoring of actin structure from monomer to polymerized protein. </LI> <LI> Polymerization rate of actin under several temperatures and heat energy. </LI> <LI> Label-free detection of protein in both of <I>in vivo</I> and <I>in vitro</I> conditions. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>Actin’s structure and assembly behavior are determined by light absorption and photoluminescence characteristics under both <I>in vitro</I> and <I>in vivo</I> conditions.</P> <P>[DISPLAY OMISSION]</P>
Hyungsuk Kim,Chang Hyun Yoo,Soo Bin Park,송현석 대한견주관절학회 2020 대한견주관절학회지 Vol.23 No.2
Background: The glenoid version of the shoulder joint correlates with the stability of the glenohumeral joint and the clinical results of total shoulder arthroplasty. We sought to analyze and compare the glenoid version measured by traditional axial two-dimensional (2D) computed tomography (CT) and three-dimensional (3D) reconstructed images at different levels. Methods: A total of 30 cases, including 15 male and 15 female patients, who underwent 3D shoulder CT imaging was randomly selected and matched by sex consecutively at one hospital. The angular difference between the scapular body axis and 2D CT slice axis was measured. The glenoid version was assessed at three levels (midpoint, upper one-third, and center of the lower circle of the glenoid) using Friedman’s method in the axial plane with 2D CT images and at the same level of three different transverse planes using a 3D reconstructed image. Results: The mean difference between the scapular body axis on the 3D reconstructed image and the 2D CT slice axis was 38.4°. At the level of the midpoint of the glenoid, the measurements were 1.7° ± 4.9° on the 2D CT images and −1.8° ± 4.1° in the 3D reconstructed image. At the level of the center of the lower circle, the measurements were 2.7° ± 5.2° on the 2D CT images and −0.5° ± 4.8° in the 3D reconstructed image. A statistically significant difference was found between the 2D CT and 3D reconstructed images at all three levels. Conclusions: The glenoid version is measured differently between axial 2D CT and 3D reconstructed images at three levels. Use of 3D reconstructed imaging can provide a more accurate glenoid version profile relative to 2D CT. The glenoid version is measured differently at different levels.