• Journal of IKEEE
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• v.27 no.4
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• pp.399-404
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• 2023

In this paper, we analyzed the current path in the O/N/O (Oxide/Nitride/Oxide) structure of 3D NAND Flash memory and in the O/N/F (Oxide/Nitride/Ferroelectric) structure where the blocking oxide is replaced by a ferroelectric. In the O/N/O structure, when V_read is applied, a current path is formed on the backside of the channel due to the E-fields of neighboring cells. In contrast, the O/N/F structure exhibits a current path formed on the front side due to the polarization of the ferroelectric material, causing electrons to move toward the channel front. Additionally, we performed an examination of device characteristics considering channel thickness and channel length. The analysis results showed that the front electron current density in the O/N/F structure increased by 2.8 times compared to the O/N/O structure, and the front electron current density ratio of the O/N/F structure was 17.7% higher. Therefore, the front current path is formed more effectively in the O/N/F structure than in the O/N/O structure.

• Journal of Distribution Science
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• v.18 no.5
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• pp.89-98
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• 2020

Purpose: The growth of online commerce is now becoming a major threat and a new opportunity for retailers. Existing offline retailers struggle to cope with new online retailers' threats by utilizing offline infrastructure. Besides, online retailers expand their online strengths to offline sales by opening their offline stores. Many retailers are paying close attention to the O2O business and the resulting changes. Thus, this research focuses on the O2O business model and process that retailers can adopt. Research design, data and methodology: Considering the features of products that retailers sell, this paper divides O2O business process with the following criteria: delivery lead-time and delivery area. And This research uses the business model canvas to define the features of O2O commerce business process. This paper also uses nine key elements in the business model canvas for analyzing the structure of O2O commerce business. Results: This paper suggests the delivery model of retailers respond to offline customer orders and summarizes the following results. (1) Considering characteristics such as logistics process, delivery area, and product type, we define the features of O2O business models: wide-area (warehouse) based O2O business model, regional area (store) based O2O business model and time-separated O2O business model. (2) This study checks the availability of the business model through the business cases of O2O business models. (3) This study also analyzes the O2O business model of domestic retail companies by the factors defined in the business model canvas. Conclusions: Retailers can adopt the O2O business process to fit their business requirements and strategy. The online retailers who deal with normal consumer products mainly have the wide-area based O2O business model. The wide-area based O2O business model can be suitable for retailers who manage inventory centrally. The time-separated O2O business model can be a good solution for fresh food retailers to operate the logistics process efficiently. And to shorten the delivery lead-time of fresh foods, the regional area based O2O business model can be fit to the retailer that utilizes its offline logistics or sales infrastructure. It may be much more important for retailers to share the inventory information with other branches and to change the role of offline stores.

• Journal of the Korean Ceramic Society
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• v.25 no.4
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• pp.373-379
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• 1988

$\alpha$-Al2O3-15m/o ZrO2 powder was prepared by a sol-gel method from boehmite and zirconium acetate. The transformation temperature of boehmite to $\alpha$-Al2O3 in the system Al2O3-ZrO2 was increased due to the coupled crystallization. On the other hand, the transformation temperature from boehmite to $\alpha$-Al2O3-15m/o ZrO2 could be prepared at 110$0^{\circ}C$ for 100min. The specific surface area of the product of $\alpha$-Al2O3-15m/o ZrO2 was 13.2$m^2$/g.

• Journal of the Korean Ceramic Society
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• v.28 no.8
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• pp.593-602
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• 1991

Al2O3 and NiO-doped Al2O3 powders were prepared from the ethanol solution of Al (NO3)3$.$9H2O and Ni(NO3)2$.$6H2O by spray pylolysis method using two-fluid nozzle. As a result of spraying test with 0.3 mol/{{{{ iota }} concentration starting solution, mean droplet sizes varied with 8.99∼9.69$\mu\textrm{m}$ and those standard deviation were 4.57∼5.12. As-prepared powders which were synthesized at 1000$^{\circ}C$ have spherical shape, sizes of 0.1∼3.0$\mu\textrm{m}$ and specific surface area of 22.34∼24.20㎡/g. Most powders consisted of {{{{ gamma }}-Al2O3 phase and transforned into ${\alpha}$-A;2O3 phase by calcination at 1100$^{\circ}C$ for 1 hr. NiO-doped Al2O3 sintered bodies had better sinterability than those of pure Al2O3 and 0.3 wt% NiO-doped Al2O3 had near theoretical density and dense microstructure.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.14 no.10
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• pp.808-814
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• 2001

The electrical properties and stabiltiy of Pr$_{6}$O$_{11}$ -based ZnO varistors, which are composed of ZnO-Pr$_{6}$O$_{11}$-Cr$_{2}$O$_{3}$-Er$_{2}$O$_{3}$ based ceramics, were investigated in the Er$_{2}$O$_{3}$ content range of 0.5 to 2.0 mol%. As Er$_{2}$O$_{3}$content is increased up to approximaterly 1.0mol%, the nonlinearity was decreased. Increasing Er$_{2}$O$_{3}$ content further caused the nonlinearity to increase. The varistors with 2.0 mol% Er$_{2}$O$_{3}$ exhibited a high nonlinearity, in which the nonlinear exponent is 47.41 and the leakage current is 1.82 $\mu$A. Furthermore, they showed a very excellent stability, in which the variation rates of the varistor voltage, the nonlinear exponent, and leakage current are -0.52%, -4.09%, and 152.75%, respectively, under DC accelerated aging stress, such as (0.80 V$_{1mA}$9$0^{\circ}C$/12h)+(0.85 V$_{1mA}$115$^{\circ}C$/12h)+(0.90 V$_{1mA}$12$0^{\circ}C$/12h)+(0.95 V$_{1mA}$1$25^{\circ}C$/12h)+(0.95 V$_{1mA}$1$25^{\circ}C$/12h).2h).TEX>/12h).2h).

• Korean Journal of Materials Research
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• v.21 no.1
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• pp.34-38
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• 2011

In this study, the effects of an annealed buffer layer with different thickness on heterojunction diodes based on the ZnO/ZnO/p-Si(111) systems were reported. The effects of an annealed buffer layer with different thickness on the structural, optical, and electrical properties of zinc oxide (ZnO) films on p-Si(111) were also studied. Before zinc oxide (ZnO) deposition, different thicknesses of ZnO buffer layer, 10 nm, 30 nm, 50 nm and 70 nm, were grown on p-Si(111) substrates using a radio-frequency sputtering system; samples were subsequently annealed at $700^{\circ}C$ for 10 minutes in $N_2$ in a horizontal thermal furnace. Zinc oxide (ZnO) films with a width of 280nm were also deposited using a radio-frequency sputtering system on the annealed ZnO/p-Si (111) substrates at room temperature; samples were subsequently annealed at $700^{\circ}C$ for 30 minutes in $N_2$. In this experiment, the structural and optical properties of ZnO thin films were studied by XRD (X-ray diffraction), and room temperature PL (photoluminescence) measurements, respectively. Current-voltage (I-V) characteristics were measured with a semiconductor parameter analyzer. The thermal tensile stress was found to decrease with increasing buffer layer thickness. Among the ZnO/ZnO/p-Si(111) diodes fabricated in this study, the sample that was formed with the condition of a 50 nm thick ZnO buffer layer showed a strong c-axis preferred orientation and I-V characteristics suitable for a heterojunction diode.

• Korean Journal of Materials Research
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• v.28 no.4
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• pp.214-220
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• 2018

We report on the fabrication and photoelectrochemical(PEC) properties of a $Cu_2O$ thin film/ZnO nanorod array oxide p-n heterojunction structure with ZnO nanorods embedded in $Cu_2O$ thin film as an efficient photoelectrode for solar-driven water splitting. A vertically oriented n-type ZnO nanorod array was first prepared on an indium-tin-oxide-coated glass substrate via a seed-mediated hydrothermal synthesis method and then a p-type $Cu_2O$ thin film was directly electrodeposited onto the vertically oriented ZnO nanorods array to form an oxide semiconductor heterostructure. The crystalline phases and morphologies of the heterojunction materials were characterized using X-ray diffraction and scanning electron microscopy as well as Raman scattering. The PEC properties of the fabricated $Cu_2O/ZnO$ p-n heterojunction photoelectrode were evaluated by photocurrent conversion efficiency measurements under white light illumination. From the observed PEC current density versus voltage (J-V) behavior, the $Cu_2O/ZnO$ photoelectrode was found to exhibit a negligible dark current and high photocurrent density, e.g., $0.77mA/cm^2$ at 0.5 V vs $Hg/HgCl_2$ in a $1mM\;Na_2SO_4$ electrolyte, revealing an effective operation of the oxide heterostructure. In particular, a significant PEC performance was observed even at an applied bias of 0 V vs $Hg/HgCl_2$, which made the device self-powered. The observed PEC performance was attributed to some synergistic effect of the p-n bilayer heterostructure on the formation of a built-in potential, including the light absorption and separation processes of photoinduced charge carriers.

• Korean Journal of Materials Research
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• v.29 no.1
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• pp.1-6
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• 2019

Recent industrialization has led to a high demand for the use of fossil fuels. Therefore, the need for producing hydrogen and its utilization is essential for a sustainable society. For an eco-friendly future technology, photoelectrochemical water splitting using solar energy has proven promising amongst many other candidates. With this technique, semiconductors can be used as photocatalysts to generate electrons by light absorption, resulting in the reduction of hydrogen ions. The photocatalysts must be chemically stable, economically inexpensive and be able to utilize a wide range of light. From this perspective, cuprous oxide($Cu_2O$) is a promising p-type semiconductor because of its appropriate band gap. However, a major hindrance to the use of $Cu_2O$ is its instability at the potential in which hydrogen ion is reduced. In this study, gold is used as a bottom electrode during electrodeposition to obtain a preferential growth along the (111) plane of $Cu_2O$ while imperfections of the $Cu_2O$ thin films are removed. This study investigates the photoelectrochemical properties of $Cu_2O$. However, severe photo-induced corrosion impedes the use of $Cu_2O$ as a photoelectrode. Two candidates, $TiO_2$ and $SnO_2$, are selected for the passivation layer on $Cu_2O$ by by considering the Pourbaix-diagram. $TiO_2$ and $SnO_2$ passivation layers are deposited by atomic layer deposition(ALD) and a sputtering process, respectively. The investigation of the photoelectrochemical properties confirmed that $SnO_2$ is a good passivation layer for $Cu_2O$.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.11a
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• pp.47-50
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• 2002

ZnO nanowires were coated conformally with aluminum oxide ($Al_{2}O_{3}$) material by atomic layer deposition (ALD). The ZnO nanowires were first synthesized on a Si (100) substrate at $1380^{\circ}C$ from ball-milled ZnO powders by a thermal evaporation procedure with an argon carrier gas without any catalysts; the length and diameter of these ZnO nanowires are $20\sim30{\mu}m$ and $50{\sim}200$ nm, respectively. $Al_{2}O_{3}$ films were then deposited on these ZnO nanowires by ALD at a substrate temperature of $300^{\circ}C$ using trimethylaluminum (TMA) and distilled water ($H_{2}O$). Transmission electron microscopy (TEM) images of the deposited ZnO nanowires revealed that 40nm-thick $Al_{2}O_{3}$ cylindrical shells surround the ZnO nanowires.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.11 no.4
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• pp.170-175
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• 2001

It was possible to grow the $Al_{2}O_{3}$ based $Y_{3}A_{5}O_{12}(YAG),ZrO_{2}$ binary and ternary eutectic fibers using micro-pulling down method with a growing rate of 0.1~15 mm/min. While $Al_{2}O_{3}/ZrO_{2}$ showed cellular-lamellar structure, $Al_{2}O_{3}$/YAG and $Al_{2}O_{3}$/YAG/$ZrO_{2}$ternary eutectic fibers showed homogeneous Chinese script lamellar structures. The microstructures of $Al_{2}O_{3}/ZrO_{2}$ binary eutectic fibers changed with solidification rate from lamellar pattern to cellular structure. The interlamellar spacing agreed with the inverse-square-root dependance on pulling rate according to $\lambda$=$kv_p\;{-1/2}$. $Al_{2}O_{3}/ZrO_{2}$ binary eutectic fibers recorded the highest tensile strength of about 1560MPa at room temperature. $Al_2O_3/YAG/ZrO_2$ternary eutectic fiber showed excellent thermal stability to $1200^{\circ}C$ without significant decrease. The maximum strength of ternary eutectic fibers recorded were 1100MPa at $25^{\circ}C$ and 970MPa at $1200^{\circ}C$, respectively.