• Journal of the Korean Physical Society
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• v.80
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• pp.1076-1080
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• 2022

For preventing a sneak current in the 3D cross-point array, the selection device is essentially necessary and an n-MOSFET has been used for the selection device. However, the three-terminal electrodes of n-MOSFET make to achieve a high density of a cross-point array difficult. As a solution, using a selector having two terminal electrodes has been intensively researched. We presented that the CuGeS₂/GeS₂-based super-linear-threshold-switching (SLTS) selector device with the insertion of optimal TiN liner thickness exhibited outstanding electrical characteristics and reliability. The dependency of electrical characteristics and reliability on various TiN liner thicknesses were investigated. In addition, the principles of reliability and electrical characteristics improvement were understood through the energy dispersive spectroscopy elemental mapping and line profile of Cu. The adequate amount of Cu distributed in GeS₂ resistive switching layer is a key factor to achieve excellent electrical characteristics and reliability for an ultra-high-density 3D cross-point array cell.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.8
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• pp.172-177
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• 2014

We present on a threshold switching device based on AsGeTeSi material which is significantly improved by two $N_2$ processes: reactive $N_2$ during deposition, and $N_2$ plasma hardening. The introduction of N2 in the two-step processing enables a stackable and thermally stable device structure, is allowing integration of switch and memory devices for application in nano scale array circuits. Despite of its good threshold switching characteristics, AsTeGeSi-based switches have had key issues with reliability at a high temperature to apply resistive memory. This is usually due to a change in a Te concentration. However, our chalconitride switches(AsTeGeSiN) show high temperature stability as well as high current density over $1.1{\times}10^7A/cm^2$ at $30{\times}30(nm^2)$ celll. A cycling performance of the switch was over $10^8$ times. In addition, we demonstrated a memory cell consisted of 1 switch-1 resistor (1S-1R) stack structure using a TaOx resistance memory with the AsTeGeSiN select device.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.134-134
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• 2009

In this work, we report that crystallization speed as well as the electrical and optical properties about the N-doped $Ge_2Sb_2Te_5$ thin films. The 200-nm-thick N-doped $Ge_2Sb_2Te_5$ thin film was deposited on p-type (100) Si and glass substrate by RF reactive sputtering at room temperature. The amorphous-to-crystalline phase transformation of N-doped $Ge_2Sb_2Te_5$ thin films investigated by X-ray diffraction (XRD). Changes in the optical transmittance of as-deposited and annealed films were measured using a UV-VIS-IR spectrophotometer and four-point probe was used to measure the sheet resistance of N-doped $Ge_2Sb_2Te_5$ thin films annealed at different temperature. In addition, the surface morphology and roughness of the films were observed by Atomic Force Microscope (AFM). The crystalline speed of amorphous N-doped $Ge_2Sb_2Te_5$ films were measured by using nano-pulse scanner with 658 nm laser diode (power : 1~17 mW, pulse duration: 10~460 ns). It was found that the crystalline speed of thin films are decreased by adding N and the crystalline temperature is higher. This means that N-dopant in $Ge_2Sb_2Te_5$ thin film plays a role to suppress amorphous-to-crystalline phase transformation.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.7
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• pp.585-593
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• 2008

In this work, we report several experimental data capable of evaluating the phase transformation characteristics of GeSbTe pseudobinary thin films comprehensively utilized as phase change materials. The phase transformation of the GeSbTe thin films was confirmed by XRD measurement from amorphous to hexagonal structure via fee structure except for $Ge_8Sb_2Te_{11}$. In addition, X-ray photoelectron spectra analysis revealed to weaken Ge-Te bond for $Ge_2Sb_2Te_5$ and to strengthen the bonds of all elements for $Ge_8Sb_2Te_{11}$ during the amorphous to crystalline transition. The values of optical energy gap $(E_{OP})$ were around 0.71 and 0.50 eV and the slopes of absorption in extended region (B) were ${\sim}5.1{\times}10^5$ and ${\sim}10{\times}10^5cm^{-1}{\cdot}V^{-1}$ for the amorphous and fcc-crystalline structures, respectively. Finally, the kinetics of amorphous-to-crystalline phase change on the GeSbTe films was characterized using a nano-pulse scanner with 658-nm laser diode (power; $1{\sim}17$ mW, pulse duration; $10{\sim}460$ ns).

• Journal of the Korean Ceramic Society
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• v.33 no.5
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• pp.507-513
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• 1996

Nonlinear optical properties of TeO2-PbO-GeO2 glasses were investigated and their correlation with struc-tural modification was investigated. Third-order nonlinear susceptibility $\chi$, ranged between 5.0$\times$10-13 esu and 10.7$\times$10-13 esu which are approximately 20-40 times larger than that of silica glass. The glass with a composition of 85(80TeO2-20PbO)-15GeO2(mol%) seemed to provide an optimum compromise between $\chi$and the stability against crystallization. Analyses of the Raman spectra suggested that these glasses are mainly composed of [TeO4] tbp, [TeO3]tp and [GeO4] tetrahedral structural units. It was concluded that the positive contribution of Pb2+ with high polarizability to $\chi$ in TeO2-PbO glasses overwhelmed the negative influence due to the structural modification of [TeO4]tbplongrightarrow[TeO3]tp. On the other hand addition of GeO2 in TeO2-PbO-GeO2 glasses resulted in the decrease of $\chi$ values. This behavior was attributed to the formation of [GeO4] polyhedra at the expense of [TeOn] polyhedra and Pb2+ ions which normally sowed a higher contribu-tion to $\chi$ than [GeO4] polyhedra.

• Food Science and Biotechnology
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• v.17 no.1
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• pp.80-84
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• 2008

The effect of gellan (GE), xanthan (XA), and $\lambda$-carrageenan (LC) on the viscosity, sedimentation, ellagic acid content, and turbidity of grape 'Campbell Early' juice (CEJ) was investigated. CEJ samples with 0.15% each of GE, XA, and LC were tested for the above variables after 0, 5, 10, and 20 days of storage. The samples containing GE (0.15%) showed the least amount of sediment formation, the lowest ellagic acid content and turbidity, and a rise in viscosity. Sedimentation in CEJ decreased with increased viscosity due to the addition of gums which also limited the ellagic acid content and turbidity. GE was the most effective additive for the stabilization of CEJ.

• Journal of Ginseng Research
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• v.41 no.3
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• pp.316-325
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• 2017

Background: Ginseng essence (GE) is a formulation comprising four medicinal and edible herbs including ginseng (Panax ginseng), American ginseng (Panax quinquefolius), lotus seed (Nelumbo nucifera), and lily bulb (Lilium longiflorum). This study was aimed at investigating the hepatoprotective effect of GE against carbon tetrachloride ($CCl_4$)-induced liver injury in rats. Methods: We treated Wistar rats daily with low, medium, and high [0.625 g/kg body weight (bw), 1.25 g/kg bw, and 3.125 g/kg bw, respectively] doses of GE for 9 wk. After the 1st wk of treatment, rats were administered 20% $CCl_4$ (1.5 mL/kg bw) two times a week to induce liver damage until the treatment ended. Results: Serum biochemical analysis indicated that GE ameliorated the elevation of aspartate aminotransferase and alanine aminotransferase and albumin decline in $CCl_4$-treated rats. Moreover, $CCl_4$-induced accumulation of hepatic total cholesterol and triglyceride was inhibited. The hepatoprotective effects of GE involved enhancing the hepatic antioxidant defense system including glutathione, glutathione peroxidase, glutathione reductase, glutathione S-transferase, superoxide dismutase, and catalase. In addition, histological analysis using hematoxylin and eosin and Masson's trichrome staining showed that GE inhibited $CCl_4$-induced hepatic inflammation and fibrosis. Furthermore, immunohistochemical staining of alpha-smooth muscle actin indicated that $CCl_4$-triggered activation of hepatic stellate cells was reduced. Conclusion: These findings demonstrate that GE improves $CCl_4$-induced liver inflammation and fibrosis by attenuating oxidative stress. Therefore, GE could be a promising hepatoprotective herbal formulation for future development of phytotherapy.

• Journal of Physiology & Pathology in Korean Medicine
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• v.21 no.5
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• pp.1219-1225
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• 2007

Immunological activities of Ginseng Radix water extract (GE) were compared with theirs of Insamhodo-tang water extract (IHT). GE and IHT (500 mg/kg) were administered p.o. twice a day for 5 days to C57BL/6 mice, respectively. IHT decreased the cell viability of murine thymocytes and splenocytes, but increased the population of $CD4^+$ cells in thymocytes, and the population of $Thy1^+$ cells and $CD4^+$ cells in splenocytes in contrast to GE. In addition, IHT decreased the phagocytic activity of peritoneal macrophages, but increased the production of nitric oxide from peritoneal macrophages in contrast to GE. These results suggest that IHT decrease a specific- and nonspecific immune reaction in comparison with GE.

• The Journal of Korean Medicine
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• v.22 no.4
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• pp.37-44
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• 2001

Objectives : Cellular death by apoptosis is an active process, depending on gene transcription and protein synthesis. It was reported that nitric oxide can induce apoptosis in several cancer cell-lines. We have previously observed that proliferation of Ll210 cells was inhibited by the administration of Gleditsiae Spina water extract (GE). In this present study, the mechanism of inhibitory action on the proliferation of L l210 cells was examined. Methods : The cell proliferation was determined by MTT assay and DNA fragmentation was determined by a flow cytometry. Results : The administration of GE decreased proliferation of L1210 cells and enhanced DNA fragmentation in vivo system. DNA fragmentation of L1210 cells was enhanced by co-culture of peritoneal macrophages obtained from GE-administered mice in vitro and it was partly inhibited by L-NMMA, nitric oxide synthetase inhibitor. In addition, GE increased nitric oxide production from peritoneal macrophages of L1210-transplanted mice. Conclusions : These results suggest that the inhibitory action of GE on proliferation of transplanted-L1210 cells is partly caused by an induction of apoptosis via production of nitric oxide in macrophages.

• Journal of Powder Materials
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• v.27 no.3
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• pp.241-246
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• 2020

To develop Gastrodia elata (GE)-loaded particles for herbal extract dosage forms, various GE-loaded particles containing dextrin, isomalt, maltodextrin, and silicon dioxide as solidifying carriers in the GE water extract are prepared using the spray drying method. Their physical properties are evaluated using the repose angle, Hausner ratio, Carr's index, weight increase rate at 40℃/75% RH condition, and scanning electron microscopy (SEM). Particles made of dextrin improve the fluidity, compressibility, and water stability. In addition, 2% silicon dioxide increases the fluidity and moisture stability. The best flowability and compressibility of GE-loaded particles are observed with TP, dextrin, and silicon dioxide amounts in the ratio of 6/4/0.2 (34.29 ± 2.86°, 1.48 ± 0.03, and 38.29 ± 2.39%, repose angle, Hausner Ratio, and Carr's index, respectively) and moisture stability with a 2% weight increase rate for 14 h at 40℃/75% RH condition. Therefore, our results suggest that the particles prepared by the spray drying method with dextrin and 2% silicon dioxide can be used as powerful particles to improve the flowability, compressibility, and moisture stability of GE.