• Journal of the Korea institute for structural maintenance and inspection
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• v.23 no.7
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• pp.40-48
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• 2019

New concept of fine dust measurement method is suggested based on ultrasonic scattering. These days, fine dust has been social problem in Korea, and many researches has been conducted including the area structural maintenance. Conventional measurement system such as optical scattering and semiconductor has a limit from environmental factors like relative humidity. However, ultrasound is based on mechanical waves, which perturb mechanical properties of medium such as density and elastic constants. Using the advantage, the algorithm for fine dust measurement is derived and evaluated using 2-D finite difference method. The numerical analysis simulates ultrasonic wave propagation inside multiple scattering medium like fine dust in air. Signal processing scheme is also suggested and the results show that the error of the algorithm is around minimum of 0.7 and maximum of 24.9 in the number density unit. It is shown that cross-section of fine dust is a key parameter to improve the accuracy of algorithm.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.29 no.4
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• pp.160-166
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• 2019

Cerium oxide ($CeO_2$, often called as Ceria) is one of the valuable rare earth oxide materials, which has been widely used for high temperature applications such as solid oxide fuel cells, automotive three-way catalysts and oxygen storage capacity. Considering those application, it is important to improve high redox and thermal stability with high surface morphology because the high surface area of $CeO_2$ could improve the catalytic reactivity at high temperature conditions. Herein we successfully fabricated hierarchical flower-like $CeO_2$ deposited via controlling pathway of precipitation reaction to supply carbonate ion lead to the flower-like morphology. The hexagonal lattice system of precipitated precursor shows better thermal stability then orthorhombic one during thermal cycling condition.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.19 no.6
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• pp.298-304
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• 2009

The effect of the surface treatments on the high temperature properties of the Inconel 617, one of the promising candidate alloys for high temperature heat-transport system, has been studied. Various surface modification methods including a rapid thermal process(RTP), a hydrothermal treatment, and a physical vapor deposition($2{\mu}m$ thick TiAlN film by an arc discharge) were applied to the Inconel 617. The morphological and the structural properties of the surface-modified Inconel 617 samples after heat treatment at $1000^{\circ}C$ in the air were compared to find out whether inhomogeneous formation of $Cr_2O_3$ crust at the surface region was suppressed or not. TiAlN-coated Inconel 617 showed homogeneous microstructure and the lowest wear loss compared to bare, RTP- and hydrothermally-treated Inconel 617 by suppressing the $Cr_2O_3$ crust formation.

• Journal of the Korea institute for structural maintenance and inspection
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• v.22 no.3
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• pp.90-96
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• 2018

In this study, the mechanical and micro-structural change of cement pastes incorporating Stainless-Steel Slag Argon Oxygen Decarburization Slag (STS-A) containing ${\gamma}-C_2S$ as a carbon capture materials were investigated with carbonation curing condition. ${\gamma}-C_2S$ is non-hydraulic, therefore does not react with water. But ${\gamma}-C_2S$ has a reactivity under carbonation curing condition with water. The reaction products fill up the pore in pastes. The microstructure of STS-A blended cement pastes could be densified by this reaction. The pore structure of cement pastes incorporating STS-A was measured using mercury intrusion porosimetry (MIP) after carbonation curing ($CO_2$ concentration is about 5%). Also the fractal characteristics were investigated for the effect of carbonation curing on the micro-structural change of paste specimens. From the results, the compressive strength of carbonated specimens incorporating STS-A increased and pore-structure of carbonated paste is more complicated.

• Journal of Life Science
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• v.9 no.6
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• pp.709-714
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• 1999

Ultrastructure of ocellar system was studied in adult Drosophila melanogaster. Ocellus was composed of terminal receptors, interneuron and glia. These three part showed different brightness each other and each component was distinct. In the glial cell, rER was abundant, and terminal receptors and interneuron showed numerous microtubules, special transporting system. The terminal receptors have particular structure referred as capital projection connecting the terminal receptor to glia. In synaptic active zone between terminal receptor and interneuron, ribbon-like structures and synaptic vesicles around the structures were frequently observed. In addition, the cross section of giant interneuron was also observed.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.38 no.7
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• pp.589-594
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• 2014

Recently, higher capacity and energy density of lithium ion batteries are increasingly demanded for enhancing their performance in view of the rise in the commercial distribution of electric and hybrid vehicles. Computational analysis of a porous structure of vanadium pentoxide cathode was performed, employing a phase field model. The incipient model was designed as a spherical structure with cylindrical-shaped pores. Modifying the diameters and lengths of the pore cylinder and the number of pores, we considered different conditions for the porous vanadium pentoxide cathodes for analyzing their effect on the amount of lithium ion intercalated to them. Subsequently, we optimized the porous structure to contain the largest amount of intercalated lithium ion during discharge.

• The Korean Journal of Zoology
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• v.30 no.3
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• pp.239-247
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• 1987

생쥐 신장의 근위세뇨관과 원위세뇨관 세포의 미세구조에 미치는 염화 메틸수은의 독성에 대한 홍삼유출물의 첨독성적 영향을 전자현징경적으로 연구하였다. 염화 메틸수은 처리군의 근위세뇨관 세포에서는 대조군에서 보다 철세 융모가 다소 축소되고 불규칙한 배열을 하였다. Brush border의 인접 부위에서는 작은 경계들이 나타나고 세포질 중앙 부위에서는 치밀체를 함유한 큰 육포들이 관색되었다. Mitochondria는 상당히 팽대되고 기양막은 부분적으로 비후되었으며 다수의 ITsosome이 나타났다. 염화 메틸수은 처리군의 원위세뇨관 세롱에서는 불규칙한 세포 표면, 양사된 세포, 그리고 다수의 ribosome과 소수의 지방사이 나타났으며 mitochondria 는 팽대되고 기고막은 부분적으로 비후되었다. 염화 메틸수은-홍삼추출물 병행 처리군의 근위세뇨관 세포에서는 염화 메틸수은 처리군에서 보다 mitochondria의 팽대 정도가 감소되었으며 육포의 크기와 수도 상당히 감소되었다. 염화 메틸수은-홍모적출물 병행 처리군의 원위세뇨관 세롱에서는 세포 표면이 어느정도 규칙적이고 mitochondria의 정해와 기저막의 비후 정도가 감소되어 정상 세포와 거의 유사하였다.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2013.05a
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• pp.178-178
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• 2013

고 해상도를 요구하는 차세대 디스플레이에서 ITO 박막은 매우 얇은 두께에서 높은 투과율과 고 전도성을 동시에 가져야 한다. 특히, 매우 얇은 박막의 경우 비정질 기판의 영향을 크게 받아 박막 초기 핵생성 및 성장에 대하여 영향을 크게 받는다. 따라서 이러한 초기 박막 핵 생성 및 성장을 제어하기 위해 불순물 Ce 함량에 따른 ITO 초박막의 전기적, 미세구조적 특성 변화를 확인하였다.

• Applied Microscopy
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• v.30 no.4
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• pp.321-326
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• 2000

The ultrastructure of the fertilized egg envelope from pale chub , Zacco platypus belong to Cyprinidae was studied using scanning and transmission electron microscopes. The fertilized egg was an adhesive type, have a single micropyle resembling the pathway of sperm in the area of the animal pole. The micropyle was surrounded by 5 peaks of hill. An outer surface of the fertilized egg envelope was arranged by pore canals irregularly. In section of fertilized egg, the egg envelope consistes of three layers, an outer adhesive layer, a middle electron dense layer and an inner lamellae layer consisting of 9 layers. These ultrastructural characters of fertilized egg envelope from pale chub can be utilized in taxonomy of teleost.

• Journal of the Korea institute for structural maintenance and inspection
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• v.17 no.6
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• pp.122-129
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• 2013

Since electrical resistivity of concrete can be measured in a more rapid and simple way than chloride diffusivity, it should be primarily regular quality control of the electrical resistivity of concrete which provides the basis for indirect of quality control of chloride diffusivity during concrete construction. If this is realized, the electrical resistivity of concrete can be a crucial parameter to establish maintenance strategy for marine concrete structures. The purpose of this study is to develop, design and test a surface electrical resistivity measurement protocol. Microstructural affecting factors such as capillary water, porosity, tourtousity, and so on, on the electrical resistivity of concrete were examined taking into account for mixing proportion properties, and hydration stage. This study can provide a non-destructive approach for durability design of marine concrete. From the relationship between electrical resistivity and chloride diffusivity, it is expected that the result is subsequently used as a calibration curve for an indirect control of the chloride diffusivity based on regular measurements of the electrical resistivity during concrete construction.