• Korean Journal of Materials Research
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• v.16 no.3
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• pp.183-187
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• 2006

We present the effects of rapid thermal annealing (RTA) temperature on the structural and optical properties of self-assembled InAs quantum dot (QD) structures grown on GaAs substrates by molecular beam epitaxy (MBE). The photoluminescence (PL) measurements are performed in a closed-cycle refrigerator as a function of temperature for the unannealed and annealed samples. RTA at higher temperature results in the increase in island size, the corresponding decrease in the density of islands, and the redshift in the PL emission from the islands. The temperature dependence of the PL peak energy for the InAs QDs is well expressed by the Varshni equation. The thermal quenching activation energies for the samples unannealed and annealed at $600^{\circ}C$ are found to be $25{\pm}5meV$ and $47{\pm}5$ meV, respectively.

• Animal cells and systems
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• v.7 no.1
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• pp.89-92
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• 2003

Immunoassays have become indispensable tools and achieved great importance in scientific and medical research. However, typical immunoassays are time-consuming and use complex, multi-step procedures. In this study, we introduce a new immunoassay system for the quantification of several analytes at a time without any washing steps. It is comprised of a detector solution with fluorescence-labeled antibodies and a test strip with immobilized capture antibodies. Using a micro-array scanner, the antigen-antibody complex was quantitatively determined by measuring the intensities of fluorescence on the capture lines or dots of nitrocellulose membrane. This method demonstrated its rapid quantitative determination of analytes without many processing steps as well as specific identification of multiple analytes in biological specimens.

• The Journal of Korea Robotics Society
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• v.2 no.2
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• pp.137-142
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• 2007

In an information-oriented society, visually impaired persons also should obtain the information with relative ease. They tend to receive the information of letters by tactile sensation through braille display systems. Several types of braille display systems have been suggested so far, but none of them have been widely used yet. The braille display system should provide multiple lines of braille units to improve the level of understanding. In this paper, we propose a cell type braille unit with $3{\times}2$ dots, each of which consists of a piezoelectric linear motor. A braille cell is small and lightweight enough to be portable, and it can be easily assembled in multiple lines. The preliminary tests using the proposed braille display system show that it can provide the information that can be well perceived by visually impaired persons.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.46 no.11
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• pp.40-47
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• 2009

In this paper, we present the design of a source driver of QVGA scale TFT-LCD driver IC which uses a mixed driving method and performs $\gamma$-correction to improve image. The source driver with 240 RGB ${\times}$ 320 dots resolution drives a TFT-LCD panel through 720 channels and implements 262k colors using 18-bit RGB data format. The mixed driving method is a mixture the channel amp. driving method with high drivability and the gray amp. driving method with small area, which remarkably reduces channel driver areas. The driver has been designed using the $0.35{\mu}m$ Magnachip embedded DRAM technology and simulated using the HSPICE simulator. The results show that our source driver operates well with y-correction and the channel driver has $17{\mu}s$ channel driving time with only 78 driving amplifiers and control logic.

• Korean Journal of Optics and Photonics
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• v.22 no.6
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• pp.247-255
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• 2011

The optical performance of LLF(Lenticular Lens Film)-based backlight was studied by using optical simulation as functions of the aspect ratio and the refractive index of lenticular lenses. In order to perform reliable simulation, the BSDF(bi-directional scattering distribution function) of the scattering dots on the bottom surface of the light guide plate was obtained as a superposition of the Lambertian and the elliptic Gaussian distribution components by comparing the experimental results and the simulation for the luminance distribution on the light guide. Based on this approach, an appropriate BSDF of the scattering dots of the light guide was constructed. The resultant values of the optimized aspect ratio and the refractive were found to be 1.25 and 1.65, respectively. In spite of the hybrid aspects of LLF incorporating both diffusing and collimating functions, the optical performance, in particular the on-axis luminance of LLF-based backlight was inferior by about 20% compared to that of conventional backlights adopting one prism film. However, the combination of two lenticular lens films resulted in comparable luminance gain as well as smooth decrease in the luminance with the viewing angle without exhibiting any side lobes.

• Journal of Sensor Science and Technology
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• v.14 no.5
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• pp.308-312
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• 2005

We present a microfluidic chip designed for the detection of antibody by using quantum dots fluorescence and a microbead-based assay. A custom designed PDMS microfluidic chip with multi-layer channel is utilized for capturing microbeads; antibody injection into each micro-well; QD injection; and fluorescence detection. The experiment using the fabricated microfluidic chip has been performed on solutions with various concentrations of antibody and has shown correlated fluorescent intensities.

• Proceedings of the Materials Research Society of Korea Conference
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• 2011.05a
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• pp.244.2-244.2
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• 2011

We introduce a novel and robust method for the preparation of nanocomposite multilayers, which allows the excellent photoluminescent (PL) properties as well as the accurate control over the composition and dimensions of multilayers. By exchanging the oleic acid stabilizers of CdSe@ZnS quantum dots (QDs) synthesized in organic solvent with 2-bromo-2-methylpropionic acid (BMPA) in the same solvent, these nanoparticles were be alternately deposited by nucleophilic substitution reaction with highly branched poly(amidoamine) dendrimer (PAMA) through layer-by-layer (LbL) assembly process. Our approach does not need to be transformed into the water-dispersible nanoparticles with electrostatic or hydrogen-bonding groups, which can deteriorate their inherent properties, for the built-up of multilayers. The nanocomposite multilayers including QDs exhibited the strong PL properties achieving densely packed surface coverage as well as long-term PL stability under atmospheric conditions in comparison with those of conventional LbL multilayers based on electrostatic interaction. Furthermore, we demonstrate that the flexible multilayer films with optical properties can be easily prepared using nucleophilic substitution reaction between bromo and amino groups in organic media. This robust and tailored method opens a new route for the design of functional film devices based on nanocomposite multilayers.

• Nano
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• v.13 no.10
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• pp.1850114.1-1850114.7
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• 2018

Here we report an optimized hot-injection method and a phase transfer strategy for the synthesis of water-soluble $CuInS_2$ QDs with desired properties. The structure and morphology studies demonstrate that the resulting QDs are $CuInS_2$ tetragonal phase with well-defined facets. It is also found that the crystal size gradually increases with the increase of reaction temperature, while the surface of QDs with pre- and post-phase transfer is functionalized with hydrophobic and hydrophilic ligands, respectively. Spectroscopy measurements reveal the size-dependent optical properties of $CuInS_2$ QDs, demonstrating the quantum confinement effect in this system.

• Proceedings of the KSPS conference
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• 2007.05a
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• pp.3-23
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• 2007

King Sejong the Great, his students in Jip-hyeun-jeon school and Choe Sejin, their successor of the sixteenth century, indicated Middle Korean had three distinctive pitches, low, high, and rising (phyeong-, geo-, sang-sheong). Thanks to $Hun-min-jeng-{\emptyset}eum$ as well as its Annotation and side-dots literatures in fifteenth and sixteenth centuries, we can compare Middle Korean with Hamgyeong dialect, Gyeongsang dialect, and extant tone dialects with joint preservers of what was probably the tonal system of unitary mother Korean language. What is most remarkable about middle Korean phonetic work is its manifest superiority in conception and execution as anything produced in the present day linguistic scholarship. But at this stage in linguistics, prior to the technology and equipment needed for the scientific analysis of sound waves, auditory description was the only possible frame for an accurate and systematic classification. And auditory phonetics still remains fundamental in pitch description, even though modern acoustic categories may supplement and supersede auditory ones in tonological analysis. Auditory phonetics, however, has serious shortcoming that its theory and practice are too subject to be developed into the present century science. With joint researchers, I am developping a new pitch scale. It is a semiautomatic auditory grade pitch analysis program. The result of our labor will give a significant breakthrough to upgrade our component in linguistics.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07a
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• pp.226-231
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• 2002

The present study discusses the results of the controlled precipitation of HgTe nanocrystals in a PbTe semiconductor matrix and demonstrates its effectiveness in producing well-organized and crystallographically aligned semiconductor nanocrystals. Following the similar procedure used in metallic alloys, the semiconductor alloys are treated at 600$^{\circ}C$ for 48 hours, quenched and aged up to 500 hours at 300$^{\circ}C$ and 450$^{\circ}C$ to induce homogeneous nucleation and growth of HgTe nanocrystalline precipitates. Examination of the resulting precipitates using transmission electron microscopy (TEM) and high resolution TEM (HRTEM) reveals that the coherent HgTe precipitates form as thin discs along the {100} habit planes making a crystallographic relation of {100}$\sub$HgTe///{100}$\sub$PbTe/ and [100]$\sub$HgTe///[100]$\sub$PbTe/. It is also found that the nato-disc undergoes a gradual thickening and a faceting under isothermal aging up to 500 hours without any noticeable coarsening. These results, combined with the extreme dimension of the precipitates (4 nm in length and sub-nanometer in thickness) and the simplicity of the formation process, leads to the conclusion that controlled precipitation is an effective method for the preparation of the desirable quantum-dot nanostructures.