• Korean Journal of Radiology
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• v.23 no.9
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• pp.854-865
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• 2022

Photon-counting detector (PCD) CT is a new CT technology utilizing a direct conversion X-ray detector, where incident X-ray photon energies are directly recorded as electronical signals. The design of the photon-counting detector itself facilitates improvements in spatial resolution (via smaller detector pixel design) and iodine signal (via count weighting) while still permitting multi-energy imaging. PCD-CT can eliminate electronic noise and reduce artifacts due to the use of energy thresholds. Improved dose efficiency is important for low dose CT and pediatric imaging. The ultra-high spatial resolution of PCD-CT design permits lower dose scanning for all body regions and is particularly helpful in identifying important imaging findings in thoracic and musculoskeletal CT. Improved iodine signal may be helpful for low contrast tasks in abdominal imaging. Virtual monoenergetic images and material classification will assist with numerous diagnostic tasks in abdominal, musculoskeletal, and cardiovascular imaging. Dual-source PCD-CT permits multi-energy CT images of the heart and coronary arteries at high temporal resolution. In this special review article, we review the clinical benefits of this technology across a wide variety of radiological subspecialties.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.281.1-281.1
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• 2016

Transition metal dichalcogenides (TMDCs) are promising layered structure materials for next-generation nano electronic devices. Many investigation on the FET device using TMDCs channel material have been performed with some integrated approach. To use TMDCs for channel material of top-gate thin film transistor(TFT), the study on high-k dielectrics on TMDCs is necessary. However, uniform growth of atomic-layer-deposited high-k dielectric film on TMDCs is difficult, owing to the lack of dangling bonds and functional groups on TMDC's basal plane. We demonstrate the effect of remote oxygen plasma pretreatment of large area synthesized few-layer MoSe2 on the growth behavior of Al2O3, which were formed by atomic layer deposition (ALD) using tri-methylaluminum (TMA) metal precursors with water oxidant. We investigated uniformity of Al2O3 by Atomic force microscopy (AFM) and Scanning electron microscopy (SEM). Raman features of MoSe2 with remote plasma pretreatment time were obtained to confirm physical plasma damage. In addition, X-ray photoelectron spectroscopy (XPS) was measured to investigate the reaction between MoSe2 and oxygen atom after the remote O2 plasma pretreatment. Finally, we have uniform Al2O3 thin film on the MoSe2 by remote O2 plasma pretreatment before ALD. This study can provide interfacial engineering process to decrease the leakage current and to improve mobility of top-gate TFT much higher.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.6
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• pp.98-103
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• 2018

Many coating technologies have been developed so far to improve the corrosion resistance, strength, abrasion resistance and other surface properties of materials and equipment. Among them, the formation of CCO (CaCoO, then CCO) thin films has been studied and used in the electronic material field. One of the characteristics of CCO thin films is that it is resistant to high temperature heat. Particularly, the method of forming the CCO thin film is relatively simple, and it was judged that it could be introduced into the existing equipment. Therefore, in this study, an experiment and analysis were carried out to determine whether the coating of CCO thin films can be applied to hot dip galvanizing facilities. A CCO thin film was formed on the surface of STS304 base material and oxidized in a Zn fume atmosphere in a $650^{\circ}C$ furnace with an air atmosphere. Oxidation was carried out for 30 days, after which the shape of the CCO thin film was confirmed by SEM and its corrosivity was analyzed through a potentiodynamic polarization experiment.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2001.05a
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• pp.244-248
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• 2001

According to the progress of the electronic industry and radio communication technologies, mankind might enjoy its abundant life. On the other hand, many social problems such as EMI, and unnecessary electromagnetic wave occur due to the increased use of electromagnetic wave. Therefore, the organizations such as CISPR, FCC, ANSI, etc. have provided the standard of electromagnetic wave environment for the countermeasure of the EMC. It had been required that the absorbing ability of an electromagnetic wave absorber is more than 20dB, the bandwidth of which is required through 30 MHz to 1,000 MHz for satisfying the international standard about an anechoic chamber for EMI/EMS measurement. From November of 1998, however, the CISPR11 has accepted the extended frequency band from 1 GHz to 18 GHz additionally in the bandwidth of EMI measurement[1]. In this paper, we proposed a new type absorber satisfying the above requirements and carried out broadband design using the equivalent material constants method. Futhermore, the experiments were carried out over the frequency band from 30 MHz to 2 GHz, and hence, the validity of the proposed design theory was confirmed.

• Journal of Fashion Business
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• v.12 no.6
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• pp.11-22
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• 2008

The goal of this study is to provide beauticians with the fundamental material to use effectively heat permanent wave in beauty industry as well as their customer's satisfaction. It carried out an experiment with damaged hair of a woman in her late twenties to investigate the change of physical and morphological characteristics by its water content when performing heat permanent wave. After spreading 0g, 1g, 2g, 3g, and 4g of water on damaged hair respectively, heat permanent wave was treated and the change of hair was observed. The change of physical characteristic was compared through permanent wave form of hair, tensile strength and elongation. The change of morphological characteristic was observed through Scanning Electron Microscope(SEM) and Transmission Electron Microscope(TEM). The result of experiment on the physical specificity revealed that permanent wave form was the most ideal when the water content was 2g, also 3g. Though the materials with much moisture content formed the results were not satisfied. The material with 0g of water content didn't make the wave. In terms of tensile strength and elongation, tensile strength was generally reduced as per the damaged degree of hair. On the contrary, elongation was increased. It observed the changes of morphological characteristic that the damage on hair cuticle was deepen, as its moisture content was decreased, and cuticle's surface was worn away. The observation of fine structure on hair section by transmission electronic microscope also certainly showed the result that damaged hair having experience with chemical treatment had got much damaged to hair cuticle as well as hair cortex. Generally chemical treatment makes hair damaged. Under consideration of this aspect, the ultimate goal of this thesis is to minimize the damage of hair caused by chemical treatment and get the satisfaction on the hair style. According to the result of experiment, the damaged hair whose moisture content was 3g showed the best permanent wave form.

• Applied Chemistry for Engineering
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• v.24 no.1
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• pp.104-111
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• 2013

Poymer blends of two degradable aliphatic polyesters, relatively expensive material polylactic acid (PLA) and relatively inexpensive material poly(butylene adipate-co-terephthalate) (PBAT), were used in this study. Three different kinds of modifiers were used with various amounts. Diisocyanate type methylenediphenyl 4,4'-diisocyanate (MDI) and hexamethylene diisocyanate (HDI) were used as modifiers and epoxy type coupling agents also used. The melt flow index (MFI) and dynamic viscoelasticity of various compositions of PLA/PBAT blends were studied. The mechanical property and morphology with respect to the fracture surface of PLA/PBAT blends were also investigated using tensile test and field emission scanning electronic microscopy, respectively. These tests were also used to verify the compatibility of PLA/PBAT and the effect of mechanical properties due to the use of modifiers. Tensile properties of PLA/PBAT blends modified with HDI were improved remarkably.

• Journal of Engineering Education Research
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• v.10 no.1
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• pp.97-108
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• 2007

Undergraduate thesis contains overall results that students has acquired to express their ability during four university years. Undergraduate thesis includes an ability to apply knowledge of engineering, communicate engineering logic and thinking effectively, and use the techniques, skills for engineering practice. In terms of an assessment tool for program outcomes, undergraduate thesis provides the results of the student with authentic, reflective, interactive and individuals features. Also undergraduate thesis provides an opportunity of improvement about curriculum and engineering program. To apply the excellency of undergraduate thesis, the principle of undergraduate thesis should be understood well and reflected the real state of engineering education. The basic concept of undergraduate thesis as a assessment tool of engineering program outcomes has been introduced. The rubrics for measuring of a specific outcome was also suggested.

• Korean Journal of Materials Research
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• v.29 no.1
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• pp.37-42
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• 2019

This study investigates Ag coated $Cu_2O$ nanoparticles that are produced with a changing molar ratio of Ag and $Cu_2O$. The results of XRD analysis reveal that each nanoparticle has a diffraction pattern peculiar to Ag and $Cu_2O$ determination, and SEM image analysis confirms that Ag is partially coated on the surface of $Cu_2O$ nanoparticles. The conductive paste with Ag coated $Cu_2O$ nanoparticles approaches the specific resistance of $6.4{\Omega}{\cdot}cm$ for silver paste(SP) as $(Ag)/(Cu_2O)$ the molar ratio increases. The paste(containing 70 % content and average a 100 nm particle size for the silver nanoparticles) for commercial use for mounting with a fine line width of $100{\mu}m$ or less has a surface resistance of 5 to $20{\mu}{\Omega}{\cdot}cm$, while in this research an Ag coated $Cu_2O$ paste has a larger surface resistance, which is disadvantageous. Its performance deteriorates as a material required for application of a fine line width electrode for a touch panel. A touch panel module that utilizes a nano imprinting technique of $10{\mu}m$ or less is expected to be used as an electrode material for electric and electronic parts where large precision(mounting with fine line width) is not required.

• Corrosion Science and Technology
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• v.20 no.4
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• pp.183-188
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• 2021

The increasing demand for energy storage in mobile electronic devices and electric vehicles has emphasized the importance of electrochemical energy storage devices such as Li-ion batteries (LIBs) and supercapacitors. For reversible Li storage, alternative anode materials are actively being developed. In this study, we designed and fabricated an Nb₂O₅-Li₃VO₄ composite for use as an anode material in LIBs and hybrid supercapacitors. Nb₂O₅ powders were dissolved into a solution and the precursors were precipitated onto Li₃VO₄ through a simple, low-temperature hydrothermal reaction. The annealing process yielded an Nb₂O₅-Li₃VO₄ composite that was characterized by X-ray diffraction, electron microscopy, and X-ray photoelectron spectroscopy. Electrochemical tests revealed that the Nb₂O₅-Li₃VO₄ composite electrode demonstrated increased capacities of approximately 350 and 140 mAh g^-1 at 0.1 and 5 C, respectively, were maintained up to 1000 cycles. The reversible capacity and rate capability of the composite electrode were enhanced compared to those of pure Nb₂O₅-based electrodes. These results can be attributed to the microstructure design of the synthesized composite material.

• Journal of the Microelectronics and Packaging Society
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• v.14 no.2 s.43
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• pp.23-33
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• 2007

The growing environmental regulation governs the use of lead by RoHS, WEEE, and then. The electronic industry is moving to replace Pb-bearing solder with Pb-free solder. To use the Pb-free solder, microelectronic industry needs consequently the new reliability appraisal such as the packaging for high temperature process, various mechanical change caused by new solder, and the development of Pb-free sloder for long life of product. The evaluation of solder bar and mechanical properties of joint were performed compared with international standard, and new appraisal standard was established. The solderability and spread ability of Sn-0.7Cu solder material showed up to the standard. Shear test of solder joint using by the solder resulted that the shear strengths after thermal shock or after aging were not much lower than the shear strength of as-soldered and that they were also up to the standard.