• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.14 no.3
• /
• pp.15-20
• /
• 2015

After the US government declared 3D printing technology a next-generation manufacturing technology, there have been many practical studies conducted to expand 3D printing technology to manufacturing technologies, called AMERICA MAKES. In particular, the Keck Center, located at the University of Texas at El Paso, has studied techniques for easily combing the 3D stacking process with space mobility and expanded these techniques to simultaneous staking techniques for multiple materials. Additionally, it developed convergence manufacturing techniques, such as direct inking techniques, in order to produce a module structure that combines electronic circuits and components, such as CUBESET. However, in these studies, it is impossible to develop a unified system using traditional independent through simple sequencing connections. This is because there are many problems in the integration between the stacking modeling of 3D printers and post-machining, such as thermal deformations, the precision accuracy of 3D printers, and independently driven coordinate problems among process systems. Therefore, in this paper, the integration method is suggested, which combines these 3D printers and subsequent machining process systems through an Internet-based cloud. Additionally, the sequential integrated system of a 3D printer, an NC milling machine, machine vision, and direct inking are realized.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.13 no.6
• /
• pp.480-489
• /
• 1988

Although CDP stacking of common depth gathering is used to get the zero-offset-section, the exploding reflector concept is examined for the modeling of zero source to receiver offset sections in this paper. The acoustic wave equation is compared with a one way wave equation which represents the upgoing wave field only. The one way wave equation used is not derived through an expansion and, therefore, can represent dips up do 90b degrees and may not lost the signals by the dipping angles. There is apparently no simple counterpart of this equation is the space domain and it can be conveniently implemented only by a Fourier method. This paper compares their modeling technique with ray tracing and wave method for over thrust structure which is one of the geological structures are dificult to process and interpret. As a result of modeling much clean and accurate signals, especially, diffractions form the corner and dipping angles can be gathered.

• Journal of the Korean Vacuum Society
• /
• v.7 no.1
• /
• pp.35-42
• /
• 1998

- The Si-$SiO_2$ interface of silicon on insulator (SOI) formed by 100 keV $O^+$ was ohserved using high resolution transmission electron microscopy (HRTEM), before and after annealing. The interface of as-implanted sample, ~$5\times 10^{17}\textrm{cm}^{-2}O^+$ implanted at $550^{\circ}C$ was very rough and it has many defectsoxide precipitate, stacking fault, coesite $SiO_2$ etc. However, the interface became flat by high temperature annealing at $1300^{\circ}C$ for 4 hour. It's roughness, observed by HRTEM, was comparable to the interface roughness of 3 keV $O_2^\;+$ ion beam oxide and -6 nm gate oxide formed by thermal oxidation.

• Proceeding of EDISON Challenge
• /
• 2015.03a
• /
• pp.14-23
• /
• 2015

Alzheimer's disease is one of the most common types of degenerative dementia. As a considerable cause of Alzheimer's disease, neurotoxic plaques composed of 39 to 42 residue-long amyloid beta($A{\beta}$) fibrils have been found in the patient's brain in large quantity. A previous study found that erythrosine B (ER), a red color food dye approved by FDA, inhibits the formation of amyloid beta fibril structures. Here, in an attempt to elucidate the inhibition mechanism, we performed molecular dynamics simulations to demonstrate the conformational change of $A{\beta}40$ induced by 2 ERs in atomistic detail. During the simulation, the ERs bound to the surfaces of both N-terminus and C-terminus regions of $A{\beta}40$ rapidly. The observed stacking of the ERs and the aromatic side chains near the N-terminus region suggests a possible inhibition mechanism in which disturbing the inter-chain stacking of PHEs destabilizes beta-sheet enriched in amyloid beta fibrils. The bound ERs block water molecules and thereby help stabilizing alpha helical structure at the main chain of C-terminus and interrupt the formation of the salt-bridge ASP23-LYS28 at the same time. Our findings can help better understanding of the current and upcoming treatment studies for Alzheimer's disease by suggesting inhibition mechanism of ER on the conformational transition of $A{\beta}40$ at the molecular level.

• Composites Research
• /
• v.34 no.4
• /
• pp.226-232
• /
• 2021

In this paper, development of tape-springs made of composite materials was conducted for the deployment structures along with design, analysis, fabrication, and numerical and experimental investigation of mechanical behavior of the tape-springs. To this end, the tape-springs were manufactured according to three stacking patterns, and numerical and experimental investigation were conducted to determine whether or not they were damaged during bending with various selected composite materials. Finally, optimal stacking patterns that do not cause damage were selected during bending. With this information, the four-point bending test was conducted to obtain the moment-rotation curves. From results, it was confirmed that the nonlinear hysteresis phenomenon of the tape-springs was properly realized according to folding and unfolding. Therefore, it was confirmed that the composite material tape spring was properly developed.

• Journal of the Institute of Electronics Engineers of Korea SD
• /
• v.47 no.8
• /
• pp.1-6
• /
• 2010

We report on the electrical properties of Ti/Al/Ni/Au (20 nm/ 150 nm/ 30 nm/ 100 nm) Ohmic contacts and the anisotropic conductivity of n-type ${\alpha}$-plane ([11-20]) GaN grown on $\gamma$-plane ([1-102]) sapphire substrates. The Ti/Al/Ni/Au Ohmic contacts and their sheet resistances are characterized by using the transfer length method (TLM) as a function of azimuthal angles. It is found that the specific contact resistance does not depend on the axis orientation and there are significant electrical anisotropy in ${\alpha}$-plane GaN films on $\gamma$-plane sapphire substrates, and the sheet resistance varies with azimuthal angles. The sheet resistance values in the direction parallel to m-axis [1-100] are 25% ~ 75% lower than those parallel to c-axis [0001] directions. Thus, Basal stacking faults (BSFs) are offered as a feasible source of the anisotropic mobility in defected m-axis direction because the band-edge discontinuities owing to the differential band gap structure.

• Journal of Korea Foundry Society
• /
• v.41 no.6
• /
• pp.505-515
• /
• 2021

Creep properties of directionally solidified Ni-based superalloy CM247LC under various temperature and stress conditions have been investigated. In the heat-treated specimen, some portion of eutectic γ-γ' remained, and uniform cubic γ' was observed in the dendrites. At low temperature (750℃) and high stress condition, a large amount of deformation occurred during the primary creep, while the tertiary creep region accounted for most of the creep deformation under high temperature and low stress condition. γ' particles are sheared by dislocation dissociated into super lattice partial dislocations separated by stacking faults at 750℃. No stacking faults in γ' were found at and above 850℃ due to the temperature dependence of the stacking fault energy. Raft structure of γ' was found after creep test at high temperature of 950℃ and 1000℃. At 850℃, the deformation mechanism was shown to be dependent on the stress condition, and so rafting was observed only under low stress condition.

• Composites Research
• /
• v.35 no.5
• /
• pp.303-308
• /
• 2022

PIC (Piecewise Integrated Composite) is a new concept for designing a composite structure with mosaically assigning various types of stacking sequences in order to improve mechanical properties of laminated composites. Also, machine learning is a sub-category of artificial intelligence, that refers to the process by which computers develop the ability to continuously learn from and make predictions based on data, then make adjustments without further programming. In the present study, the tapered box beam type PIC robot arm for carrying and transferring wide and thin LCD display was designed based on the machine learning in order to increase structural stiffness. Essential training data were collected from the reference elements, which were intentionally designated elements among finite element models, during preliminary FE analysis. Additionally, triaxiality values for each finite element were obtained for judging the dominant external loading type, such as tensile, compressive or shear. Training and evaluating machine learning model were conducted using the training data and loading types of elements were predicted in case the level accuracy was fulfilled. Three types of stacking sequences, which were to be known as robust toward specific loading types, were mosaically assigned to the PIC robot arm. Henceforth, the bending type FE analysis was carried out and its result claimed that the PIC robot arm showed increased stiffness compared to conventional uni-stacking sequence type composite robot arm.

• Economic and Environmental Geology
• /
• v.56 no.3
• /
• pp.277-291
• /
• 2023

To analyze the crustal velocity structures beneath 21 broadband seismic stations in Gangwon Province, South Korea, we first applied the H-κ stacking method to 139 teleseismic event data (Mw ≥ 5.8 and the epicentral distance of 30° - 90°) occurring between March 18, 2019 and December 31, 2022 to estimate the Moho depths and V_p/V_s ratios beneath each station. The Moho depths and V_p/V_s ratios from the H-κ stacking method range from 24.9 to 33.2 km depth and 1.695 - 1.760, respectively, and the estimated V_p/V_s ratios were applied to the joint inversion of receiver functions and surface wave dispersion to obtain 1-D crustal velocity models beneath each station. The resulting Moho depths range from 25.9 to 33.7 km depth, similar to the results from the H-κ stacking method. Moho depth results from the both methods are generally consistent with Airy's isostasy. The 1-D crustal velocity models confirm that the existence of 2 km thick low-velocity layers with P-wave velocities of 5 km/s or less at some stations in the Taebaeksan basin, and at the stations CHNB and GAPB in northern Gangwon Province, which are located above the Cenozoic sedimentary layer. The station SH2B, although not overlying a sedimentary layer, has a low P-wave velocity near the surface, which is probably due to various factors such as weathering of the bedrock. We also observe a velocity inversion with decreasing velocity with depth at all stations within 4 - 12 km depths, and mid-crustal discontinuities possibly due to density differences in the rocks at around 10 km depth below some stations.

• Bulletin of the Korean Chemical Society
• /
• v.33 no.9
• /
• pp.2917-2924
• /
• 2012

Four novel metal-organic complexes $[Cd_2(IP)_2(TBZ)_2(H_2O)_2]{\cdot}(H_2O)$ (1), $[Zn_4(IP)_4(TBZ)_4]{\cdot}2(H_2O)$ (2), $[Zn_2(BTC)(TBZ)_2(CO_2H)]$ (3), [Co(PDC)(TBZ)] (4) (where IP = isophthalate; TBZ = thiabendazole; BTC = 1,3,5-benzenetricarboxylate; PDC = pyridine-3,4-dicarboxylate) have been prepared and characterized by IR spectrum, elemental analysis, thermogravimetric analysis, and single-crystal X-ray diffraction. X-ray structure analysis reveals that 1, 2, and 3 are one-dimensional chain polymers, while 4 is a two-dimensional network polymer. The TBZ acts as a typical chelating ligand coordinated to the metal center in all complexes. The 1D chain architecture of 1 is constructed from isophthalates and cadmium atoms. A simultaneous presence of chelating, monodentate and bidentate coordination modes of IP ligands is observed in complex 2. In complex 3, the 16-membered rings are alternately arranged forming an infinite 1D double-chain structure. The 2D skeleton of 4 is formed by cobalt ions as nodes and PDC dianions as spacers, through coordination bonds. The hydrogen bonds and ${\pi}-{\pi}$ stacking play important roles in affecting the final structure where complexes 1 and 3 have 2D supramolecular networks, while complexes 2 and 4 have 3D supramolecular architectures.