• Journal of the Korean Chemical Society
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• v.22 no.3
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• pp.184-193
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• 1978

Various aluminum chloride polymeric catalysts have been prepared by the reaction of anhydrous aluminum chloride with styrene-divinylbenzene copolymer bead in the carbon disulfide solvent. The shapes of aluminum chloride polymeric catalysts have been investigated by the use of optical microscope, scanning electron microscope and analysis of atomic absorption and electron microprobe X-ray. The catalytic effect of aluminurn chloride polymeric catalysts in the process of esterification of various organic acids with several aliphatic and aromatic alcohols have been studied.

• Applied Microscopy
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• v.42 no.4
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• pp.218-222
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• 2012

Modern aberration-corrected transmission electron microscope (TEM) with appropriate electron beam energy is able to achieve atomic resolution imaging of single and bilayer graphene sheets. Especially, atomic configuration of bilayer graphene with a rotation angle can be identified from the direct imaging and phase reconstructed imaging since atomic resolution Moir$\acute{e}$ pattern can be obtained successfully at atomic scale using an aberration-corrected TEM. This study boosts a reliable stacking order analysis, which is required for synthesized or artificially prepared multilayer graphene, and lets graphene researchers utilize the information of atomic configuration of stacked graphene layers readily.

• Applied Microscopy
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• v.13 no.1
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• pp.41-47
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• 1983

A Scanning electron microscope which can obtain additional information not readily available with either the light or transmission electron microscope was used to study the mast cell shape and its granules in normal mammal tissue(rat mesentery, stomach and mouse stomach) by fretting cut using liquid nitrogen. The results showed that rat mesentery and mouse stomach mast cell surfaces had no ridges and microvilli, but revealed several microvilli projecting into the surrounding connective tissue in the rat stomach mast cell. The shape of the mast cell varied from discoid(in the rat mesenteric mast cell) to ellipsoid (rat and mouse stomach), ranging from 7.5 to $10{\mu}m$ in diameter. The shape of the nucleus was ellipsoid and nucleic membrane was adherent to the outer surface of the granules. The granules, approximately 0.2 to $0.9{\mu}m$ in diameter, were various shapes. Frequently, rounded protrusions of cytoplasmic granules could be discerned under the cell membrane. Many small granules were seen in the cytoplasm.

• Applied Microscopy
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• v.13 no.1
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• pp.63-70
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• 1983

The cell division of Bacillus thuringiensis are studed by a electron microscope. It was observed that when the cell division was occurred, the bacterial transverse septeum was centripetally formed, and the bacterial spore was divided into two daughter cells. The fore spore septum was initiated by invagination from either sides of the cell membranes, and was easily distinguished it from the transverse septum of the vegetative cell division. The large vesicular mesosome was. observed at one end of the cell membrane. The nucleoids were of variously irregular shapes and had no a nuclear membrane. The morphology of the bacteria was visualizd by a scanning electron microscope. The surface of the cell was generally rough and had a single polar flagellum, which was appeared to be $0.2{\mu}$ in width and $13{\mu}$ in length.

• Ceramist
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• v.22 no.4
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• pp.417-428
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• 2019

Even though, nanoscale materials of various shapes and compositions have been synthesized in the liquid, their underlying growth and transformation mechanisms are not well understood due to a lack of analytical methods. The advent of liquid cell for transmission electron microscope (TEM) enables the direct imaging of chemical reactions that occur in liquids with nanometer resolution of the electron microscope (EM). Here, the technical development of liquid cell TEM equipment and their applications to the study of nanomaterials analysis in liquid are discussed. Also new findings discovered through liquid cell TEM studies such as nucleation & growth, coalescence process and transformation are discussed.

• Journal of the Mineralogical Society of Korea
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• v.11 no.1
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• pp.13-19
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• 1998

Textures of claystones of the Cheonunsan Formation in the Hwasoon area have been studied using optical microscope and electron microprobe. Microscopic images were observed under the optical microscope using the transmitted polarizing light from thin sections and under the electron microprobe using the back-scattered electron beam from the polished sections. Identification of minerals were made using X-ray diffraction analysis and chemical analysis by electon microprobe. Textural analyses show that the original sedimentary claystones rich in aluminium were subjected to metamorphism by which they changed to the metamorphosed claystone consisting mainly of chloritoid, quartz, andalusite and illite. Later intensive hydrothermal kaolinization of this metamorhosed claystones resulted in the formation of high-aluminous claystones rich in kaolinite exhibiting various complicated replacement textures.

• Journal of the Korean Ceramic Society
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• v.56 no.3
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• pp.291-297
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• 2019

Pyrolytic carbon (PyC) layers were deposited using methane. The PyC layer deposited with 5% methane showed highly textured graphite, while that deposited using 100% methane showed low textured graphite. The degrees of anisotropy of the carbon layers were measured using an X-ray diffractometer, a transmission electron microscope, and a Raman spectroscope, and the results were compared with those reported previously. The orientation angles obtained from the fast Fourier transformation of the high-resolution transmission electron microscopy images and the I_D/I_G intensity ratios obtained from the Raman spectra were used to evaluate the anisotropy of the PyC layers.

• Development and Reproduction
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• v.17 no.2
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• pp.121-132
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• 2013

Ultrastructural characteristics of the germ cells and accessory cells in testis during spermatogenesis and taxonomic values of mature sperm morphology of Ruditapes philippinarum were investigated by the transmission electron microscope and scanning electron microscope observations. The testis is the diffuse organ that consists of branching acini containing developing germ cells and accessory cells associated with spermatogenesis. The morphology of the spermatozoon is of the primitive type and is somewhat different to those of other bivalves. The morphologies of the sperm nucleus type and the acrosome shape of this species have a cylinderical type and a modified cone shape, respectively. As some ultrastructural characteristics of the acrosomal vesicle, the peripheral parts of two basal rings show electron opaque part, while the apex part of the acrosome shows electron lucent part. These characteristics of sperm belong to the family Veneridae in the subclass Heterodonta, unlike a characteristic of the subclass Pteriomorphia showing all part of the acrosome being composed of electron opaque part. In particular, a cylinder-like nucleus of the sperm is curved. The spermatozoon is approximately $48-51{\mu}m$ in length, including a long acrosome (about $2.4{\mu}m$ in length), a curved sperm nucleus (about $3.40{\mu}m$ in length), and a tail flagellum. The axoneme of the sperm tail shows a 9+2 structure.

• Proceedings of the Materials Research Society of Korea Conference
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• 2012.05a
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• pp.56.1-56.1
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• 2012

The microstructures and mechanical properties of Co-29Cr-6Mo alloy with C and N additions, produced by additive manufacturing using electron beam melting (EBM) method, were studied using X-ray diffraction, electron back scatter diffraction, transmission electron microscope, Vickers hardness tests, and tensile tests, focusing on the influences on the build direction and the various heat treatments after build. It is found that the microstructures for the as built specimens were changed from columnar to equiaxed grain structure with average grain size of approximately $10-20{\mu}m$ due to the heat treatment employing the reverse transformation from a lamellar (hcp + $Cr_2N$) phase to an fcc. Our results will contribute to the development of biomedical Ni-free Co-Cr-Mo-N-C alloys, produced by EBM method, with refined grain size and good mechanical properties, without requiring any hot workings.

• Applied Microscopy
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• v.45 no.3
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• pp.115-118
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• 2015

In this review paper, I'd like to introduce the basics of angle-resolved photoemission spectroscopy (ARPES) and some of my results taken at the Pohang Accelerator Laboratory (PAL), the only synchrotron radiation in South Korea. The results show that ARPES is very useful, in particular, for studying two-dimensional materials. It looks like a microscope in momentum space similar to transmission electron microscope imaging atoms in real space.