• Journal of the Society of Cosmetic Scientists of Korea
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• v.47 no.2
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• pp.133-138
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• 2021

In this study, Niacinamide (NI) was loaded into solid lipid nanoparticles (SLNs) and skin permeability was evaluated to improve skin permeability of NI, which was a skin whitening substance. NI was able to effectively load within SLN with a double-melting emulsification method, producing stable particles with average particle sizes of 263.30 to 436.93 nm and a zeta potential of -34.77 to -57.60 mV. Artificial skin tissue (SkinEthic^TM RHE) derived from skin keratinocytes derived from human epidermal tissue was used for the skin permeation study of NI. Skin transmittance and deposition experiments of NI confirmed that all SLN formulations improved skin transmittance and deposition rates of NI, approximately 5.4 ~ 7.6 and 9.5 ~ 20.8 improvement over SLN applications. Therefore, SLN manufactured in this study have shown sufficient results to improve the skin permeability of the functional whitening substance, NI.

• Composites Research
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• v.37 no.1
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• pp.32-39
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• 2024

Solid-state hydrogen storage is gaining prominence as a crucial subject in advancing the hydrogen-based economy and innovating energy storage technology. This storage method shows superior characteristics in terms of safety, storage, and operational efficiency compared to existing methods such as compression and liquefied hydrogen storage. In this study, we aim to evaluate the solid hydrogen storage performance on the nanotube surface by various structural design factors. This is accomplished through molecular dynamics simulations (MD) with the aim of uncovering the underlying ism. The simulation incorporates diverse carbon nanotubes (CNTs) - encompassing various diameters, multi-walled structures (MWNT), single-walled structures (SWNT), and boron-nitrogen nanotubes (BNNT). Analyzing the storage and effective release of hydrogen under different conditions via the radial density function (RDF) revealed that a reduction in radius and the implementation of a double-wall configuration contribute to heightened solid hydrogen storage. While the hydrogen storage capacity of boron-nitrogen nanotubes falls short of that of carbon nanotubes, they notably surpass carbon nanotubes in terms of effective hydrogen storage capacity.

• Journal of Periodontal and Implant Science
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• v.52 no.4
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• pp.338-350
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• 2022

Purpose: Various studies have investigated 3-dimensional (3D)-printed implants using Ti6Al-4V powder; however, multi-root 3D-printed implants have not been fully investigated. The purpose of this study was to explore the stability of multirooted 3D-printed implants with lattice and solid structures. The secondary outcomes were comparisons between the 2 types of 3D-printed implants in micro-computed tomographic and histological analyses. Methods: Lattice- and solid-type 3D-printed implants for the left and right mandibular third premolars in beagle dogs were fabricated. Four implants in each group were placed immediately following tooth extraction. Implant stability measurement and periapical X-rays were performed every 2 weeks for 12 weeks. Peri-implant bone volume/tissue volume (BV/TV) and bone mineral density (BMD) were measured by micro-computed tomography. Bone-to-implant contact (BIC) and bone area fraction occupancy (BAFO) were measured in histomorphometric analyses. Results: All 4 lattice-type 3D-printed implants survived. Three solid-type 3D-printed implants were removed before the planned sacrifice date due to implant mobility. A slight, gradual increase in implant stability values from implant surgery to 4 weeks after surgery was observed in the lattice-type 3D-printed implants. The marginal bone change of the surviving solid-type 3D-printed implant was approximately 5 mm, whereas the value was approximately 2 mm in the lattice-type 3D-printed implants. BV/TV and BMD in the lattice type 3D-printed implants were similar to those in the surviving solid-type implant. However, BIC and BAFO were lower in the surviving solid-type 3D-printed implant than in the lattice-type 3D-printed implants. Conclusions: Within the limits of this preclinical study, 3D-printed implants of double-rooted teeth showed high primary stability. However, 3D-printed implants with interlocking structures such as lattices might provide high secondary stability and successful osseointegration.

• Structural Engineering and Mechanics
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• v.12 no.2
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• pp.201-214
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• 2001

Four finite element (FE) models are examined to find the one that best estimates moment-rotation characteristics of top- and seat-angle with double web-angle connections. To efficiently simulate the real behavior of connections, finite element analyses are performed with following considerations: 1) all components of connection (beam, column, angles and bolts) are discretized by eight-node solid elements; 2) shapes of bolt shank, head, and nut are precisely taken into account in modeling; and 3) contact surface algorithm is applied as boundary condition. To improve accuracy in predicting moment-rotation behavior of a connection, bolt pretension is introduced before the corresponding connection moment being surcharged. The experimental results are used to investigate the applicability of FE method and to check the performance of three-parameter power model by making comparison among their moment-rotation behaviors and by assessment of deformation and stress distribution patterns at the final stage of loading. This research exposes two important features: (1) the FE method has tremendous potential for connection modeling for both monotonic and cyclic loading; and (2) the power model is able to predict moment-rotation characteristics of semi-rigid connections with acceptable accuracy.

• Structural Engineering and Mechanics
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• v.41 no.2
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• pp.285-297
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• 2012

An inverse approach is presented for calculating the flexibility coefficient of open-side cracks in the cross sectional of beams. The cracked cross section is treated as a massless rotational spring which connects two segments of the beam. Based on the Euler-Bernoulli beam theory, the differential equation governing the forced vibration of each segment of the beam is written. By using a mathematical manipulation the time dependent differential equations are transformed into the static substitutes. The crack characteristics are then introduced to the solution of the differential equations via the boundary conditions. By having the time history of transverse response of an arbitrary location along the beam, the flexibility coefficient of crack is calculated. The method is applied for some cracked beams with solid rectangular cross sections and the results obtained are compared with the available data in literature. The comparison indicates that the predictions of the proposed method are in good agreement with the reported data. The procedure is quite general so as to it can be applicable for both single-side crack and double-side crack analogously. Hence, it is also applied for some test beams with double-side cracks.

• Proceedings of the KIEE Conference
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• 1997.07d
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• pp.1326-1329
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• 1997

In this paper, PNN-PZN-PZT ceramics were fabricated with various mole ratio of the PZT[$Pb(Zr_{1/2}Tid_{1/2})O_3$]. PNN [$Pb(Ni_{1/3}Nb_{2/3})O_3$] and PZN[$Pb(Ni_{1/3}Nb_{2/3})O_3$ powders prepared by double calcination and PZT powders prepared by molten-salt synthesis method. The formation rate of perovskite phase in PNN-PZN-PZT ceramics could be obtained about 92% at PZT 0.3 mole ratio. The relative permittivity of specimen with PZT 0.3 mole ratio was shown 5,320 and appeared the relaxor ferroelectric feature. The maximum piezoelectric coefficient $d_{31}$ to be used for evaluation the displacement of piezoceramics in PNN-PZN-PZT ceramics was $324{\times}10^{-12}$(C/V) at the vicinity of morphotropic phase boundary and was larger than that of solid PZT ceramics($120{\times}10^{-12}C/V$).

• Current Optics and Photonics
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• v.4 no.2
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• pp.134-140
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• 2020

A significant enhancement of the magneto-optical Faraday rotation and extraordinary optical transmission (EOT) in the cascaded double-fishnet (CDF) structure with periodic rectangular apertures is theoretically predicted by using the extended finite difference time domain (FDTD) method. The results demonstrate that the transmittance spectrum of the CDF structure has two EOT resonant peaks in a broad spectrum spanning visible to near-infrared wavebands, one of them coinciding with the enhanced Faraday rotation and large figure of merit (FOM) at the same wavelength. It is most important that the resonant position and intensity of the transmittance, Faraday rotation and FOM can be simply tailored by adjusting the incident wavelength, the thickness of the magnetic layer, and the offset between two metallic rectangular apertures, etc. Furthermore, the intrinsic physical mechanism of the resonance characteristics of the transmittance and Faraday rotation is thoroughly studied by investigating the electromagnetic field distributions at the location of resonance. It is shown that the transmittance resonance is mainly determined by different hybrid modes of surface plasmons (SPs) and plasmonic electromagnetically induced transparency (EIT) behavior, and the enhancement of Faraday rotation is mostly governed by the plasmonic electromagnetically induced absorption (EIA) behavior and the conversion of the transverse magnetic (TM) mode and transverse electric (TE) mode in the magnetic dielectric layer.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2004.04a
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• pp.97-100
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• 2004

The identification of the DNA structure as a double-stranded helix consting of two nucleotide chain molecules was a milestone in modern molecular biology. The DNA chip technology is based on reverse hybridization that follows the principle of complementary binding of double-stranded DNA. DNA chip can be described as the deposition of defined nucleic acid sequences, probes, on a solid substrate to form a regular array of elements that are available for hybridization to complementary nucleic acids, targets. DNA chips based on cDNA clons, oligonucleotides and genomic clons have been developed for gene expression studies, genetic variation analysis and genomic changes associated with disease including cancers and genetic diseases. DNA chips for gene expression profiling can be used for functional analysis in human eel Is and animal models, disease-related gene studies, assessment of gene therapy, assessment of genetically modified food, and research for drug discovery. DNA chips for genetic variation detection can be used for the detection of mutations or chromosomal abnormalities in cnacers, drug resistances in cancer cells or pathogenic microbes, histocompatibility analysis for transplantation, individual identification for forensic medicine, and detection and discrimination of pathogenic microbes. The DNA chip will be generalized as a useful tool in clinical diagnostics in near future. Lab-on-a chip and informatics will facilitate the development of a variety of DNA chips for diagnostic purpose.

• Earthquakes and Structures
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• v.18 no.4
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• pp.451-466
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• 2020

In this paper, the effect of Engineered Cementitious Composites (ECC) on the lateral strength of a bearing unreinforced Masonry (URM) wall, was experimentally and numerically investigated. Two half scale solid walls were constructed and were tested under quasi-static lateral loading. The first specimen was an un-retrofitted masonry wall (reference wall) while the second one was retrofitted by ECC mortar connected to the wall foundation via steel rebar dowels. The effect of pre-compression level, ECC layer thickness and one or double-side retrofitting on the URM wall lateral strength was numerically investigated. The validation of the numerical model was carried out from the experimental results. The results indicated that the application of ECC layer increases the wall lateral strength and the level of increment depends on the above mentioned parameters. Increasing pre-compression levels and the lack of connection between the ECC layer and the wall foundation reduces the influence of the ECC mortar on the wall lateral strength. In addition, the wall failure mode changes from flexure to the toe-crashing behavior. Furthermore, in the case of ECC layer connected to the wall foundation, the ECC layer thickness and double-side retrofitting showed a significant effect on the wall lateral strength. Finally, a simple method for estimating the lateral strength of retrofitted masonry walls is presented. The results of this method is in good agreement with the numerical results.

• Korea-Australia Rheology Journal
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• v.15 no.2
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• pp.83-90
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• 2003

In cases of the microfluidic channel, the electrokinetic influence on the transport behavior can be found. The externally applied body force originated from the electrostatic interaction between the nonlinear Poisson-Boltzmann field and the flow-induced electrical field is applied in the equation of motion. The electrostatic potential profile is computed a priori by applying the finite difference scheme, and an analytical solution to the Navier-Stokes equation of motion for slit-like microchannel is obtained via the Green's function. An explicit analytical expression for the induced electrokinetic potential is derived as functions of relevant physicochemical parameters. The effects of the electric double layer, the zeta potential of the solid surface, and the charge condition of the channel wall on the velocity profile as well as the electroviscous behavior are examined. With increases in either electric double layer or zeta potential, the average fluid velocity in the channel of same charge is entirely reduced, whereas the electroviscous effect becomes stronger. We observed an opposite behavior in the channel of opposite charge, where the attractive electrostatic interactions are presented.