• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.48 no.1
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• pp.5-18
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• 2016

Electron microscopy is an important investigation and analytical method for the morphological characterization of various cellulosic materials, such as micro-crystalline cellulose (MCC), microfibrillated cellulose (MFC), nanofibrillated cellulose (NFC), and cellulose nanocrystals (CNC). However, more accurate morphological analysis requires high-quality micrographs acquired from the proper use of an electron microscope and associated sample preparation methods. Understanding the interaction of electron and matter as well as the importance of sample preparation methods, including drying and staining methods, enables the production of high quality images with adequate information on the nanocellulosic materials. This paper provides a brief overview of the micro and nano structural analysis of cellulose, as investigated using transmission and scanning electron microscopy.

• Computers and Concrete
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• v.18 no.1
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• pp.113-137
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• 2016

Extensive experimental studies on remarkable mechanical properties Polypropylene Fibre Reinforced Self-compacting Concrete (PFRSCC) have been executed, including different fibre volume fractions of Polypropylene fibers (0.25%, 0.5%, 0.75%, and 1%) and different water to cement ratios (0.21, 0.34, 0.38, and 0.41). The experimental program was carried out by using two hundred and sixteen specimens to obtain the impact resistance and mechanical properties of PFRSCC materials, considering compressive strength, splitting tensile strength, and flexural strength. Statistical and analytical studies have been mainly focused on experimental data to correlate of mechanical properties of PFRSCC materials. Statistical results revealed that compressive, splitting tensile, and flexural strengths as well as impact resistance follow the normal distribution. Moreover, to correlate mechanical properties based on acquired test results, linear and nonlinear equations were developed among mechanical properties and impact resistance of PFRSCC materials.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.653-657
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• 2005

AGV is very useful equipment to transfer containers in automated container terminal. AGV must have Obstacle Detection System (ODS) for port automation. ODS needs the function to classify some specified object from background in acquired data. And it must be able to track classified moving objects. Finally, ODS could determine its next action for safe driving whether it should do emergency stop or speed down, or it should change its deriving lane. For these functions, ODS can have many different kinds of algorithm. In this paper, we present one of AGV to be used in automated container terminal.

• Journal of the Korean Vacuum Society
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• v.12 no.S1
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• pp.40-45
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• 2003

Ru interfacial layer was inserted into Mo-on-Si interface to enhance the extreme ultra-violet (EUV) reflective multilayer properties. The stacking status and optical properties are analyzed using cross-sectional transmission electron microscope (TEM), and reflectometer. About 1.5% of maximum reflectivity can be acquired as predicted in optical simulation, which is thought to be originated from the diffusion inhibition property. Phase defect correctability of the multilayer can be enhanced by the insertion of Ru barrier layer.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.51 no.10
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• pp.473-478
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• 2002

Accelerated thermal aging conditions of polymeric materials were studied by Kissinger equation with TGA analysis. The activation energy was obtained from the slope of straight line of each specimen at the different TGA heating rate. Estimating activation energy from Kissinger equation was acquired, and the resulting calculation showed that 3.59, 3.0, 3.86, 3.73 for the PEEK, polyimide, polysulfone and Viton, respectively. The studied polymeric specimens are used for electrical penetration assembly in nuclear power plant. Accelerated aging time and temperature were also determined corresponding to actual service temperature and 41 years.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.11 no.2
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• pp.7-11
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• 2015

Recently, as the demand for sustainable energy sources is increasing, ground-source heat pump (GSHP) systems are receiving growing attention. However, the initial cost of GSHP system is higher than it of the conventional systems, especially, in small-size buildings. Therefore, for the application to the small-size building, it is necessary to develop small-size ground heat exchanger with small-size buildings. In this study, analysis of unit-type heat exchanger due to grouting materials. As a result, 1492.14 W of heat exchange rate was acquired in the condition of cement-silica sand-graphite materials.

• Structural Engineering and Mechanics
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• v.76 no.5
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• pp.591-598
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• 2020

Ultrasonic waves provide a non-destructive and sensitive way to monitor the concrete hydration. However, limited works are reported to monitor the evolution of the mechanical parameter at early ages. In this study, modified piezoelectric aggregates are embedded inside a concrete beam to excite and receive primary waves. A hydration index, namely, the variation of ultrasonic waveform (VUW) is developed to characterize the variation of the transmitted waves during the hydration process. The recorded hydration indices are compared with the compressive strength measured by destructive test at different ages. The results show that the VUW is closer to the compressive strength than the other two traditional hydration indices, ultrasonic velocity and wave packet energy. The proposed VUW provides a simple and accurate way to monitor the concrete hydration at early ages.

• Journal of the Korean Ceramic Society
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• v.44 no.3 s.298
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• pp.157-161
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• 2007

Line width under $100\;{\mu}m$ with good resolution is difficult to achieve using conventional thick-film process utilizing screen printing method. However combined with lithography technology finer line and space for miniaturization and highly integrated package is achievable. In this study, photosensitive Ag paste of optimum formulation used for thick film lithography technology was fabricated by various Ag powder, glass powder and additives. As the result, line width of $30\;{\mu}m$ with good definition and reduced mismatch during co-firing with LTCC substrate was acquired. Formulated Ag paste was used to pattern embedded fine line inductor with over 90% yield.

• Imaging Science in Dentistry
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• v.47 no.4
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• pp.247-254
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• 2017

Purpose: Dual-energy X-ray imaging is widely used today in various areas of medicine and in other applications. However, no similar technique exists for dental applications. In this study, we propose a dual-energy technique for dental diagnoses based on voltage-switching. Materials and Methods: The method presented in this study allowed different groups of materials to be classified based on atomic number, thereby enabling two-dimensional images to be colorized. Computer simulations showed the feasibility of this approach. Using a number of different samples with typical biologic and synthetic dental materials, the technique was applied to radiographs acquired with a commercially available dental X-ray unit. Results: This technique provided a novel visual representation of the intraoral environment in three colors, and is of diagnostic value when compared to state-of-the-art grayscale images, since the oral cavity often contains multiple permanent foreign materials. Conclusion: This work developed a technique for two-dimensional dual-energy imaging in the context of dental applications and showed its feasibility with a commercial dental X-ray unit in simulation and experimental studies.

• Applied Microscopy
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• v.43 no.2
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• pp.88-97
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• 2013

Technical investigation to figure out the problems arising during in-situ heating electron backscatter diffraction (EBSD) analysis inside scanning electron microscopy (SEM) was carried out. EBSD patterns were successfully acquired up to $830^{\circ}C$ without degradation of EBSD pattern quality in steels. Several technical problems such as image drift and surface microstructure pinning were taking place during in-situ experiments. Image drift problem was successfully prevented in constant current supplying mode. It was revealed that the surface pinning problem was resulted from the $TiO_2$ oxide particle formation during heating inside SEM chamber. Surface pinning phenomenon was fairly reduced by additional platinum and carbon multi-layer coating before in-situ heating experiment, furthermore was perfectly prevented by improvement of vacuum level of SEM chamber via leakage control. Plane view in-situ observation provides better understanding on the overall feature of recrystallization phenomena and cross sectional in-situ observation provides clearer understanding on the recrystallization mechanism.