• 한국전자현미경학회:학술대회논문집
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• 2000.11a
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• pp.61-64
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• 2000

• Bulletin of the Korean Chemical Society
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• v.29 no.2
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• pp.467-470
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• 2008

• Proceedings of the Materials Research Society of Korea Conference
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• 2008.05a
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• pp.17.1-17.1
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• 2008

• Bulletin of the Korean Chemical Society
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• v.33 no.2
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• pp.657-662
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• 2012

Mercaptoacetic acid (MAA) and mercaptopropionic acid (MPA) capped ZnS:Mn nanocrystals were synthesized and their physical characteristics were examined by XRD, HR-TEM, EDXS, and FT-IR spectroscopy. The optical properties of the MPA capped ZnS:Mn nanocrystals dispersed in aqueous solution were also measured by UV/Vis and solution photoluminescence (PL) spectra, which showed a broad emission peak around 598 nm (orange light emissions) with calculated relative PL efficiency of 5.2%. Comparative toxicity evaluation of the uncoordinated ligands, MAA and MPA, with the corresponding ZnS:Mn nanocrystals revealed that the original ligands significantly suppressed the growth of wild type E. coli whereas the ligandcapped nanocrystals did not show significant toxic effects. The reduced cytotoxicity of the conjugated ZnS:Mn nanocrystals was also observed in NIH/3T3 mouse embryonic fibroblasts. These results imply that potential toxicities of the capping ligands can be neutralized on ZnS:Mn surface.

• Journal of the Korean Vacuum Society
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• v.10 no.2
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• pp.247-251
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• 2001

Photoluminescence(PL) were observed from room temperature to 8K on $Si^+$-implanted silicon-oxide films. The PL intensities are increased from room temperature to 50~80K and decreased below 50K. The blue-shift occurs during the increasing of PL intensity. Also, temperature-dependent PL were measured at peak wavelengths. The first peak is the most sensitive to the measuring temperature. The experimental results are explained by quantum size effect of O rich defects or(and) Si rich defects rather than nanocrystal silicon.

• Journal of Ocean Engineering and Technology
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• v.25 no.6
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• pp.80-85
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• 2011

The Ultrasonic Nanocrystal Surface Modification (UNSM) technology improves the fatigue life of a torsion bar by inducing compressive residual stress on the surface layer. The UNSM is applied to replace the presetting method and shot peening technology. The torsion bar must be changed periodically because of a lack of durability and a phenomenon related to the stress relaxation. The torsion fatigue test specimens were made of DIN17221 material, and the results showed that the fatigue life was 5 times more than under durability test conditions. A comparison test between the commercial vehicles' presetting method and shot peened torsion bar and the UNSM torsion bar showed that the UNSM could replace the presetting method and shot peening.

• Transactions on Electrical and Electronic Materials
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• v.12 no.5
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• pp.218-221
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• 2011

We modified the optical properties of the $CuInS_2$ nanocrystal (NC) by alloying. Nanocrystals (NCs) with alloyed cores were synthesized by refluxing the as-synthesized $CuInS_2$ NCs with a mixture of cadmium acetate, zinc acetate and palmitic acid. The shift in emission wavelength of the NCs after shell layer formation was minimized by alloying. The photoluminescence (PL) spectra showed significant reduction of emission intensity. A detailed study on the emission process of NCs implies that the formation of shell layers with small lattice mismatch minimized the mismatch strain generated from the shell layers in contrast to core alloyed NCs. In particular, time-resolved PL spectra of the NCs showed a significant increase in the lifetime of excited carriers by modifying the band alignment of the NCs by modifying the shell composition.

• Current Photovoltaic Research
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• v.2 no.4
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• pp.152-156
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• 2014

We report hybrid solar cells fabricated with polymer/fullerene bulk heterojunction layers that contain inorganic nanocrystals synthesized by in-situ reaction in the presence of polymer chains. The inorganic (cadmium sulfide) nanocrystal ($CdS_{NC}$) was generated by the reaction of cadmium acetate and sulfur by varying the reaction time up to 30 min. The synthesized $CdS_{NC}$ showed a rectangular flake shape, while the size of $CdS_{NC}$ reached ca. 150 nm when the reaction time was 10 min. The performance of hybrid solar cells with $CdS_{NC}$ synthesized for 10 min was better than that of a control device, whereas poor performances were measured for other hybrid solar cells with $CdS_{NC}$ synthesized for more than 10 min.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.24 no.5
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• pp.530-534
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• 2015

Ultrasonic nanocrystal surface modification (UNSM) is an example of a nanoscale-surface modification that has become noticeable because of its effects on the mechanical improvement of metallic materials. UNSM equipment needs to be both utilized and improved. The equipment is based on an ultrasonic waveguide whose role is to strike surfaces of metallic materials to achieve nanoscale deformation. In this paper, we introduce the development of one kind of UNSM equipment. Using piezoelectric elements, we repeatedly design and fabricate a 20-kHz ultrasonic waveguide. With respect to the composition of the equipment, the waveguide is automatically transferred by two axial stages automatically. In addition, a static force is constantly applied by pneumatic devices. We perform an experiment to verify the feasibility of the equipment.

• Current Research on Agriculture and Life Sciences
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• v.31 no.4
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• pp.250-255
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• 2013

As a renewable nanomaterial, cellulose nanocrystal (CNC) isolated from wood grants excellent mechanical properties in developing high performance nanocomposites. This study was undertaken to compare the reinforcing efficiency of two different CNCs, i.e., cellulose nanowhiskers (CNWs) and cellulose nanofibrils (CNFs) from hardwood bleached kraft pulp (HW-BKP) as reinforcing agent in polyvinyl alcohol (PVA)-based nanocomposite. The CNWs were isolated by sulfuric acid hydrolysis while the CNFs were isolated by 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO)-mediated oxidation. Based on measurements using transmission electron microscopy, the individual CNWs were about $6.96{\pm}0.87nm$ wide and $178{\pm}55nm$ long, while CNFs were $7.07{\pm}0.99nm$ wide. The incorporation of CNWs and CNFs into the PVA matrix at 5% and 1% levels, respectively, resulted in the maximum tensile strength, indicating different efficiencies of these CNCs in the nanocomposites. Therefore, these results suggest a relationship between the reinforcing potential of CNCs and their physical characteristics, such as their morphology, dimensions, and aspect ratio.