• Nano
• /
• v.13 no.11
• /
• pp.1850125.1-1850125.12
• /
• 2018

To reduce the imbalance of impedance matching between the magnetic metal nanowires and free space, $Fe/TiO_2$ core/shell nanowire arrays with different diameters were fabricated in the templates of anodic aluminum oxide membranes by electrodeposition. The influences of the microstructure on the microwave absorption properties of the $Fe/TiO_2/Al_2O_3$ composites were studied by the transmission/reflection waveguide method. It was demonstrated experimentally that both the interfacial polarization and the diameter of the $Fe/TiO_2$ core/shell nanowires have critical effects on the microwave absorption properties. We also investigated the angle dependence of the microwave absorption properties. Due to the interfacial polarization and associated relaxation, the $Fe/TiO_2/Al_2O_3$ composites exhibited optimal microwave absorption properties when microwave propagation direction was accordant with the axis of the nanowires. Finally, we managed to obtain an optimal reflection loss of below -10 dB (90% absorption) over 10.2-14.8 GHz, with a thickness of 3.0 mm and the minimum value of -39.4 dB at 11.7 GHz.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.23 no.8
• /
• pp.8-13
• /
• 2009

LED BLU(Back Light Unit), based on MCPCB(Metal Core Printed Circuit Board) with anodizing oxide dielectric layer and improved thermal dissipation property, are presented. Reflecting cups were also formed on the surface of the MCPCB such that optical coupling between neighboring chips were minimized for improving the photon extraction efficiency. LED chips were directly attached on the MCPCB by using the COB (Chip On Board) scheme.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2001.03a
• /
• pp.249-256
• /
• 2001

Optical Color Corescanner firstly developed by DMT-GeoTec, Germany and further upgraded through the Korea-Germany joint project is capable of duplicating the core surfaces. The tool uses a digital CCD line camera. As the core is rotated by an electric motor, the camera scans the uppermost line, everytime with a circumferential increment of up to 0.05mm(20pixels/mm) and hence a complete 360$^{\circ}$ unwrapped image(core image) is produced. This paper illustrated diverse research benefits of such core images from several test sites in our country. All scanned images could be stored as a data-base one and easily used with software facilities \circled1 to evaluate a percental distribution of mineral components or grain size etc. not only for the rock classification but also for e.g. the assessment of building stones, \circled2 to study potential reservoirs as a hydrocarbon indicator using ultraviolet fluorescence reflection from cores, \circled3 to facilitate the qualitative and quantitative analysis of fractures, \circled4 to evaluate the fractures and thin bedded reservoirs using spectral color responses. Based on abundant scanning experiments, it would seem that this imaging work should lead to reflecting the future trend in underground survey toward a more comprehensive understanding of the properties and behaviors of in situ rocks.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2014.02a
• /
• pp.314.2-314.2
• /
• 2014

To improve the optical and electrical properties of commercialized GaN-based light-emitting diodes (LEDs), many methods are suggested. In recent years, great efforts have been made to improve the internal quantum efficiency and light extraction efficiency (LEE) and promising approaches are suggested using a patterned sapphire substrate (PSS), V-pit embedded LED structures, and silica nanostructures. In this study, we report on the enhancement of photoluminescence (PL) intensity in GaN-based LED structures by using the combination of SiO2 (silica) nanospheres and polystyrene/SiO2 core-shell nanospheres. The SiO2 nanospheres-coated LED structure shows the slightly increased PL intensity. Moreover the polystyrene/SiO2 core-shell nanospheres-coated structure shows the more increase of PL intensity comparing to that of only SiO2 spheres-coated structure and the conventional structure without coating of nanospheres. The Finite-difference time-domain (FDTD) simulation results show corresponding result with experimentally observed results. The mechanism of enhancement of PL intensity using the coating of polystyrene/SiO2 core-shell nanospheres on LED surface can be explained by the improvement in extraction efficiency by both increasing the probability of light escape by reducing Fresnel reflection and by multiple scattering within the core-shell nanospheres.

• Stress
• /
• v.26 no.4
• /
• pp.268-276
• /
• 2018

Background: The purpose of this study is to evaluate the effects of the Motivational Interviewing (MI) based communication training for third-year nursing students. Methods: This study use a quasi-experimental design with pre and post-test to evaluate a 4-hour MI based communication training. This training was offered to 35 third-year nursing students who were participating in elective psychiatric nursing clerkship course. Each student completed pre and post questionnaire which includes assessment of motivational interviewing skills as measured by Helpful Response Questionnaire (HRQ). Also confidence (5 items) in using MI based communication knowledge and core skills were included. Data were independently analyzed by two coders and blindly rated the pre and post HRQ self-reported responses. Data were analyzed using paired t-test, descriptive analysis. Results: Nursing students showed increasing use of reflection (4.10~5.67, p<.001), decreasing use of closed-ended question (2.00~0.73, p<.001), road blocks (2.94~0.64, p<.001), and improve in depth of reflection (12.79~20.86 p<.001). But they did not show significant changes in open-ended question (2.01~2.33, p=.257). Confidence in the interview has increased overall, except for reflecting. The overall satisfaction with the training was quite high, and the most helpful training method was group and individual feedback. Conclusions: This study provides evidences that 4 hour-training is effective in core skills such as reflection and depth of reflection, and also confidence in interviews. It is necessary to develop step-by-step training modules to enhance undergraduate communication skills. It is necessary to develop an effective training strategy focused on students' confidence in open-ended questions and reflection.

• The Journal of the Acoustical Society of Korea
• /
• v.23 no.4
• /
• pp.296-302
• /
• 2004

Acoustic experiments are performed for a seafloor classification from 19 May to 25 May 2003. The six different sites of bottom composition are settled and the bottom reflection losses with frequencies (30, 50, 80. 100, 120 kHz) are measured. Sediment samples were collected using gravity core and the sample was extracted for grain size analysis. The fuzzy logic is used to classify the seabed. In the fuzzy logic. Bottom 1083 model of frequency dependence is used as the input membership functions and the output membership functions are composed of the Wentworth grain size of the bottom. The possibility of the seafloor classification is verified comparing the inversed mean grain size using fuzzy logic with the results of the coring.

• Proceedings of the Korean Society For Composite Materials Conference
• /
• 2004.04a
• /
• pp.1-4
• /
• 2004

In this paper we developed Composite-Smart-Structures(CSS) using sandwich structure composed of Glass/Epoxy laminates and Nomex honeycomb and microstrip antenna. Transmission/reflection theory shows that antenna performances can be improved due to multiple reflection by Glass/Epoxy facesheet, and honeycomb is used for air gap between antenna and facesheet. Stacked radiating patches are used for the wideband. Facesheet and honeycomb thicknesses are selected considering both wideband and high gain. Measured electrical performances show that CSS has wide bandwidth over $10\%$ and higher gain by 3.5dBi than initially designed antenna, and no doubt it has excellent mechanical performances by sandwich effect given by composite laminates and honeycomb core. The CSS concept can be extended to give a useful guide for manufacturers of structural body panels as well as antenna designers, promising innovative future communication technology.

• Journal of the Korean Institute of Telematics and Electronics
• /
• v.24 no.5
• /
• pp.868-873
• /
• 1987

Holographic diffraction gratings which are the core element of the optical instruments such as a spectrophotometer have been fabricated using the photoresist as a recording material. A 488nm line from an argon laser is used in making the gratings. Transmission type surface-relief phase grating and reflection type which is fabsricated by coating the aluminum on the transmission type with thickness 2000\ulcornerare fabricated, the spatical frequency of which are 1200 lines/mm. Diffraction efficiency, scattered light and wave-front aberratin are measured to test the performance of the developed gratings. A marimum diffraction efficiency is given when light is incident at the Bragg angle. Theoretical efficiency is about 80%, but measured efficiency of the transmission type and reflection type is 50% and 45%, respectively.

• Current Optics and Photonics
• /
• v.4 no.6
• /
• pp.551-557
• /
• 2020

A mirror-in-slab waveguide is fabricated on a slab waveguide by using the refractive-index contrast between two materials, with the reflection performance depending on the slab waveguide's design. In this research, a slab waveguide design consisting of silicon (Si) as the core and SiO2 as the substrate was designed and developed to determine the coupling, waveguide, and mirror losses. Based on experimental results, coupling loss is dominant and is affected by the design of the slab waveguide. Furthermore, the mirror loss is affected by the design of the mirror, such as the curvature radius and the size of the mirror. TE and TM polarizations of light are used in the measurements. The experimental results show that mirror losses due to reflection by mirrors are 0.011 dB/mirror and 0.007 dB/mirror for TE and TM polarizations respectively. A simulation was performed to confirm whether the size of mirror is sufficient to reflect the input light, and to check the quality of the surfaces of fabricated mirrors.

• Journal of the Korean Society for Precision Engineering
• /
• v.25 no.12
• /
• pp.39-46
• /
• 2008

Asymmetric glass lens core for portable projection optic system was designed and simulated. And it was machined by newly developed non-rotational ultra precision grinding method. With the designed lens data which optimized for multi-collimation, we generated the we core surface data. Mold pressing conditions analyzed by FEM. In the machining process, ground profile errors were compensated based on measured data, minimized feed rate and depth of cut. The deviations of machined core profile were acceptable level for glass mold press. Mold pressed glass array lens was coated with $SiO_2\;and\;Ta_2O_5$ for anti-reflection.