• Journal of the Korean Vacuum Society
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• v.18 no.5
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• pp.352-357
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• 2009

The InAs multi-quantum dots (MQDs) solar cell and InGaAs multi-quantum wells (MQWs) solar cell to cover 1.1 eV and 1.3 eV were designed by 1D poisson, respectively. The MQDs and MQWs of 5, 10, 15 layers were grown by molecular beam epitaxy. The photo luminescence results showed that the 5 period stacked MQDs have the highest intensity at around 1.1 eV with 57.6 meV full width at half maximum (FWHM). Also we can observe 10 period stacked MQWs peak position which has highest intensity at 1.31 eV with 12.37 meV FWHM. The density and size of QDs were observed by reflection high energy electron diffraction pattern and atomic force microscope. Futhermore, AlGaAs/GaAs sandwiched tunnel junctions were modified according to the width of GaAs layer on p-type GaAs substrates. The structures with GaAs width of 30 nm and 50 nm have backward diode characteristics. In contrast, tunnel diode characteristics were observed in the 20 nm of that of sample.

• Korean Journal of Materials Research
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• v.4 no.3
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• pp.268-279
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• 1994

The x-ray powtler pattern of single phase $Bi_2S_2CaCu_2O_{8+x}$ has been identified and fullyindexed using a pseudotetragonal subcell with a= 5.408, c = 30.83 $\AA$ and an incommensurate supercellwith reciprocal lattice vector, X$q^*$, given by $q^*=0.211b^*-c^*$. The x -ray powder pattern of the Pb-free110K superconductor phase "$Bi_2S_2CaCu_2O_{10+x}$" has many lines which belong t.o an incommensuratesupercell. Using elect.ron d~ffraction pImt.ographs as a indexing guide, an indexing scheme for the powderpattern has been obtained. The unit cell has a geometrically orthorhombic subcell a=5.411, b= 5.420, c=37.29(2) $\AA$. Supercell reflections have indices that are derived from the subcell k, 1 indices by addition uf$\pm q^*$, where $\pm q^*=0.211b^*-0.78c^*$The incommensurate con~ponent In the b dwection, $\delta$, is the same for both phases but on going from2212 to 2223 phase, the superlattic component in the c direction changes from commensurate($\varepsilon$=1) toincommensurate($\varepsilon$=0.78).X>$\varepsilon$=0.78).

• Journal of Pharmacopuncture
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• v.19 no.4
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• pp.319-328
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• 2016

Objectives: Advancements in nanotechnology have led to nanoparticle (NP) use in various fields of medicine. Although the potential of NPs is promising, the lack of documented evidence on the toxicological effects of NPs is concerning. A few studies have documented that homeopathy uses NPs. Unfortunately, very few sound scientific studies have explored the toxic effects of homeopathic drugs. Citing this lack of high-quality scientific evidence, regulatory agencies have been reluctant to endorse homeopathic treatment as an alternative or adjunct treatment. This study aimed to enhance our insight into the impact of commercially-available homeopathic drugs, to study the presence of NPs in those drugs and any deleterious effects they might have, and to determine the distribution pattern of NPs in zebrafish embryos (Danio rerio). Methods: Homeopathic dilutions were studied using high-resolution transmission electron microscopy with selected area electron diffraction (SAED). For the toxicity assessment on Zebrafish, embryos were exposed to a test solution from 4 - 6 hours post-fertilization, and embryos/larvae were assessed up to 5 days post-fertilization (dpf ) for viability and morphology. Toxicity was recorded in terms of mortality, hatching delay, phenotypic defects and metal accumulation. Around 5 dpf was found to be the optimum developmental stage for evaluation. Results: The present study aimed to conclusively prove the presence of NPs in all high dilutions of homeopathic drugs. Embryonic zebrafish were exposed to three homeopathic drugs with two potencies (30CH, 200CH) during early embryogenesis. The resulting morphological and cellular responses were observed. Exposure to these potencies produced no visibly significant malformations, pericardial edema, and mortality and no necrotic and apoptotic cellular death. Conclusion: Our findings clearly demonstrate that no toxic effects were observed for these three homeopathic drugs at the potencies and exposure times used in this study. The embryonic zebrafish model is recommended as a well-established method for rapidly assessing the toxicity of homeopathic drugs.

• Applied Microscopy
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• v.40 no.3
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• pp.155-162
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• 2010

Bone is a hierarchically structured composite material which has been well studied by the materials engineering community because of its unique structure and mechanical properties. Bone is a laminated organic-inorganic composite composed of primarily hydroxyapatite, collagen and water. The main mineral that gives bone's hardness is calcium phosphate, which is also known as hydroxyapatite. Light microscopy (LM) and transmission electron microscopy (TEM) were used to study the structure of femurs from chicken and rabbit. The elemental analysis was used to search variation in the distribution of calcium, potassium and oxygen in the femur. Current investigation focused on two structural scales: micro scale (arrangement of compact bone) and nano scale (collagen fibril and apatite crystals). At micro scale, distinct difference was found in microstructures of chicken femur and rabbit femur. At nano scale, we analyzed the shape and size of apatite crystals and the arrangement of collagen fibril. Consequently, femurs of chicken and rabbit had very similar chemical property and structures at nano scale despite of their different species.

• Transactions of the Korean hydrogen and new energy society
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• v.10 no.2
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• pp.119-130
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• 1999

After preparing $Mg_2Ni_{1-x}{^{57}}Fe_x$(x=0.015, 0.03, 0.06, 0.12 and 0.24) alloys, they were studied by $M{\ddot{o}}ssbauer$ resonance. The $M{\ddot{o}}ssbauer$ spectra of x=0.015 and 0.03 alloys exhibit two doublets (doublet 1, 2). That of x=0.06 alloys shows two doublets (doublet 1,2) and one six-line, and those of x=0.12 and 0.24 alloys have only one six-line. The doublet 1 for x=0.015, 0.03 and 0.06 alloys is considered to result from a fraction of Fe in excess showing a superparamagnetic behavior. The doublet 2 is considered to result from the Fe substituted for Ni in the $Mg_2Ni$ phase. The values of isomer shift 0.24 ~ 0.28 mm/s suggest that the iron exist in the state $Fe^{+3}$. The result that the quadrapole splitting of the doublet 2 is not zero shows that the distribution of electrons around the iron is asymmetric. Their values for the doublet 2, 1.20 ~ 1.38 mm/s, approach the value of quadrapole for the oxidation number +3. The six-line showing the magnetic hyperfine interactions results from the iron which has not substituted the nickel in the $Mg_2Ni$ phase. The $M{\ddot{o}}ssbauer$ spectra of the hydrided alloys with x=0.015 and 0.03 show six-line. This suggests that the iron segregates with the hydriding reaction. The analysis results of the $M{\ddot{o}}ssbauer$ spectrum, the variation of magnetization with magnetic field, Auger electron spectroscopy and electron diffraction show the segregation of Ni and the formation of MgO. This is considered to result from the reaction of the $Mg_2Ni$ phase with the oxygen contained in the hydrogen as impurity.

• Journal of the Microelectronics and Packaging Society
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• v.28 no.1
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• pp.47-54
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• 2021

For the bonding of smaller PCB solder bumps of less than 100 microns, an experiment was performed to make up a tin plating solution and find plating conditions in order to produce a bump pattern through tin electroplating, replacing the previous PCB solder bumps process by microballs. After SR patterning, a Cu seed layer was formed, and then, through DFR patterning, a pattern in which Sn can be selectively plated only within the SR pattern was formed on the PCB substrate. The tin plating solution was made based on methanesulfonic acid, and hydroquinone was used as an antioxidant to prevent oxidation of divalent tin ions. Triton X-100 was used as a surfactant, and gelatin was used as a grain refiner. By measuring the electrochemical polarization curve, the characteristics of organic additives in Triton X-100 and gelatin were compared. It was confirmed that the addition of Triton X-100 suppressed hydrogen generation up to -1 V vs. NHE, whereas gelatin inhibited hydrogen generation up to -0.7 V vs. NHE. As the current density increased, there was a general tendency that the grain size became finer, and it was observed that it became finer when gelatin was added.

• Journal of the Korea Computer Industry Society
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• v.6 no.5
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• pp.757-766
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• 2005

There have been great demands for higher density SRAM in all area of SRAM applications, such as mobile, network, cache, and embedded applications. Therefore, aggressive shrinkage of 6T Full CMOS SRAM had been continued as the technology advances, However, conventional 6T Full CMOS SRAM has a basic limitation in the cell size because it needs 6 transistors on a silicon substrate compared to 1 transistor in a DRAM cell. The typical cell area of 6T Full CMOS SRAM is $70{\sim}90F^{2}$, which is too large compared to $8{\sim}9F^{2}$ of DRAM cell. With 80nm design rule using 193nm ArF lithography, the maximum density is 72M bits at the most. Therefore, pseudo SRAM or 1T SRAM, whose memory cell is the same as DRAM cell, is being adopted for the solution of the high density SRAM applications more than 64M bits. However, the refresh time limits not only the maximum operation temperature but also nearly all critical electrical characteristics of the products such as stand_by current and random access time. In order to overcome both the size penalty of the conventional 6T Full CMOS SRAM cell and the poor characteristics of the TFT load cell, we have developed $S^{3}$ cell. The Load pMOS and the Pass nMOS on ILD have nearly single crystal silicon channel according to the TEM and electron diffraction pattern analysis. In this study, we present $S^{3}$ SRAM cell technology with 100nm design rule in further detail, including the process integration and the basic characteristics of stacked single crystal silicon TFT.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.19 no.4
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• pp.314-321
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• 2006

There have been great demands for higher density SRAM in all area of SRAM applications, such as mobile, network, cache, and embedded applications. Therefore, aggressive shrinkage of 6 T Full CMOS SRAM had been continued as the technology advances. However, conventional 6 T Full CMOS SRAM has a basic limitation in the cell size because it needs 6 transistors on a silicon substrate compared to 1 transistor in a DRAM cell. The typical cell area of 6 T Full CMOS SRAM is $70{\sim}90\;F^2$, which is too large compared to $8{\sim}9\;F^2$ of DRAM cell. With 80 nm design rule using 193 nm ArF lithography, the maximum density is 72 Mbits at the most. Therefore, pseudo SRAM or 1 T SRAM, whose memory cell is the same as DRAM cell, is being adopted for the solution of the high density SRAM applications more than 64 M bits. However, the refresh time limits not only the maximum operation temperature but also nearly all critical electrical characteristics of the products such as stand_by current and random access time. In order to overcome both the size penalty of the conventional 6 T Full CMOS SRAM cell and the poor characteristics of the TFT load cell, we have developed S3 cell. The Load pMOS and the Pass nMOS on ILD have nearly single crystal silicon channel according to the TEM and electron diffraction pattern analysis. In this study, we present $S^3$ SRAM cell technology with 100 nm design rule in further detail, including the process integration and the basic characteristics of stacked single crystal silicon TFT.

• Nuclear Engineering and Technology
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• v.52 no.6
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• pp.1222-1230
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• 2020

The corrosion rates of the reactor pressure vessel materials of SA508 Grade 3 were measured using a weight loss method in aerated boric acid solutions to simulate the evaporation of leaked PWR primary water in an ambient environment. The corrosion behavior and products were examined using X-ray diffraction and electron microscopy. SA508 showed typical general corrosion characteristics. The corrosion rate increased steadily as the boron concentration was increased. As the immersion time elapsed, the corrosion rate slowly or rapidly decreased according to the oxidation reaction of iron. The corrosion rate showed a complicated pattern depending on the temperature; it increased gradually and then rapidly decreased again when reaching a certain transition temperature. The corrosion products of SA508 were found to be FeO(OH), Fe₂O₃, and Fe₃O₄. As the boron concentration decreased and the temperature was increased, the formation of Fe₃O₄ was more favorable as compared to the formation of FeO(OH) and Fe₂O₃. Consequently, the changes of the corrosion rate and behavior were closely related to the oxidation reaction of iron on the surface. The corrosive damage to SA508 appears to be most severe when the oxidation reaction is such that Fe₂O₃ forms as a corrosion product.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.16 no.5
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• pp.181-188
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• 2006

Rutile single crystals grown by skull melting method were cut parallel and perpendicular to growth axis, and both sides of the cut wafers (${\phi}5.5mmx1.0mm$) were then polished to be mirror surfaces. The black wafers were changed into pale yellow color by annealing in air at 1200 and $1300^{\circ}C$ for $3{\sim}15\;and\;10{\sim}50$ hours, respectively. After annealing, structural and optical properties were examined by specific gravity (S.G), SEM-electron backscattered pattern (SEM-EBSP), X-ray diffraction (XRD), FT-IR transmittance spectra, laser Raman spectroscopy (LRS), photoluminescence (PL) and X-ray photoelectron spectroscopy (XPS). These results are analyzed increase of weight in air, decrease of weight in water and specific gravity, shown secondary phase of needle shape, diffusion of oxygen ion and increase of $Ti^{3+}$. From the above results, we suggest that the skull melting method grown rutile single crystals contain defect centers such as $O_v,\;Ti^{3+},\;O_v-Ti^{3+}$ interstitials and $F^+-H^+$.