• Korean Journal of Metals and Materials
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• v.48 no.1
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• pp.57-61
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• 2010

Nanosized surface structures of Cu powders were investigated at the atomic scale by field-emission transmission electron microscope techniques. The nanoscale surface oxide layer on the Cu powder was analyzed to be the $CU_2O$ phase by electron diffraction pattern and electron energy-loss spectroscopy. In addition, it was found from high-resolution transmission electron microscopy study that there are formed no surface oxide layers on the surface of alkanethiol coated Cu powders.

• Vacuum Magazine
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• v.4 no.4
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• pp.18-22
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• 2017

Transmission electron microscopy (TEM) is a versatile and powerful technique that enables direct visualization of biological samples of sizes ranging from whole cell to near-atomic resolution details of a protein molecule. Thanks to numerous technical breakthroughs and monumental discoveries, 3D electron microscopy (3DEM) has become an indispensable tool in the field of structural biology. In particular, development of cryo-electron microscopy(cryo-EM) and computational image processing played pivotal role for the determination of 3D structures of complex biological systems at sub-molecular resolution. Here, basis of TEM and 3DEM will be introduced, especially focusing on technical advancements and practical applications. Also, future prospective of constantly evolving 3DEM field will be discussed, with an anticipation of great biological discoveries that were once considered impossible.

• 한국전자현미경학회:학술대회논문집
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• 1994.05a
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• pp.27-27
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• 1994

• 한국전자현미경학회:학술대회논문집
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• 1993.06a
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• pp.28-29
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• 1993

• Applied Microscopy
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• v.43 no.3
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• pp.122-126
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• 2013

The heterogeneous nucleation of the ${\Theta}^{\prime}$ phase on nanoscale precipitates has been investigated using a combination of three-dimensional atom probe tomography and high-resolution transmission electron microscopy. Two types of ${\Theta}^{\prime}$ phases were observed, namely small (~2 nm thick) cylindrical precipitates and larger (~100 nm) globular precipitates and both appear to be heterogeneously nucleated on the nanoscale precipitates. The composition and crystal structure of precipitates were directly analyzed by combination of two advanced characterization techniques.

• Applied Microscopy
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• v.44 no.4
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• pp.133-137
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• 2014

We suggest a facile transmission electron microscopy (TEM) specimen preparation method for the direct (polymer-free) transfer of layer-area graphene from Cu substrates to a TEM grid. The standard (polymer-based) method and direct transfer method were by TEM, high-resolution TEM, and energy dispersive X-ray spectroscopy (EDS). The folds and crystalline particles were formed in a graphene specimen by the standard method, while the graphene specimen by the direct method with a new etchant solution exhibited clean and full coverage of the graphene surface, which reduced several wet chemical steps and accompanying mechanical stresses and avoided formation of the oxide metal.

• Korean Journal of Materials Research
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• v.18 no.3
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• pp.123-127
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• 2008

The production of tin oxide ($SnO_2$) microrods on iridium (Ir)-coated substrates was achieved through the thermal evaporation of Sn powders in which a sufficiently high $O_2$ partial pressure was employed. Scanning electron microscopy revealed that the product consisted of microrods with diameters that ranged from 0.9 to $40\;{\mu}m$. X-ray diffraction, high-resolution transmission electron microscopy, and selected area electron diffraction indicated that the microrods were $SnO_2$ with a rutile structure. As the microrod tips were free of metal particles, it was determined that the growth of $SnO_2$ microrods via the present route was dominated by a vapor-solid mechanism. The thickening of rod-like structures was related to the utilization of sufficiently high $O_2$ partial pressure during the synthesis process, whereas low $O_2$ partial pressure facilitated the production of thin rods.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.53 no.6
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• pp.312-315
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• 2004

The monolayer of oxygen atoms sandwiched between the adjacent nanocrystalline silicon layers was formed by ultra high vacuum-chemical vapor deposition (UHV-CVD). This multilayer Si-O structure forms a new type of superlattice, semiconductor-atomic superlattice (SAS). According to the experimental results, high-resolution cross-sectional transmission electron microscopy (HRTEM) shows epitaxial system. Also, the current-voltage (Ⅰ-Ⅴ) measurement results show the stable and good insulating behavior with high breakdown voltage. It is apparent that the system may form an epitaxially grown insulating layer as possible replacement of silicon-on-insulator (SOI), a scheme investigated as future generation of high efficient and high density CMOS on SOI.

• Applied Microscopy
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• v.47 no.3
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• pp.160-164
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• 2017

Electron crystallography has been used as the one of powerful tool for studying the structure of biological macromolecules at high resolution which is sufficient to provide details of intramolecular and intermolecular interactions at near-atomic level. Previously it commonly uses two-dimensional crystals that are periodic arrangement of biological molecules, however recent studies reported a novel technical approach to electron crystallography of three-dimensional crystals, called micro electron-diffraction (MicroED) which involves placing the irregular and small sized protein crystals in a transmission electron microscope to determine the atomic structure. In here, we review the advances in electron crystallography techniques with several recent studies. Furthermore, we discuss the future direction of this structural approach.

• Applied Microscopy
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• v.47 no.3
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• pp.203-207
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• 2017

A homogeneous $KNbO_3$ (KN) phase was formed by sintering at $1,040^{\circ}C$ for 1 hour, without formation of the $K_2O$-deficient secondary phase even though suffering the minor loss of $K_2O$. KN liquid phase was formed during sintering and abnormal grain growth occurred in this specimen. The detailed microstructural observations on KN during sintering were carried out using high resolution transmission electron microscopy. The ledged structures were found at the KN grain boundary and the abnormal grain growth was performed by the lateral migration of these ledges in the presence of the liquid phase. The liquid pockets were found in the KN grains. They have various external shapes mainly due to the kinetic factors. They have atomically flat interfaces with some ledges with one atomic height. The slight deficient $K_2O$ by evaporation might somewhat reduce the melting point of KN from the reported at $1,058^{\circ}C$. The liquid pockets play an important role in supplying the liquid phase during the abnormal grain growth in the sintering process of KN ceramics.