• Journal of Microbiology and Biotechnology
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• v.26 no.8
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• pp.1457-1463
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• 2016

Vibrio anguillarum, a devastating pathogen causing vibriosis among marine fish, is prevailing in worldwide fishery industries and accounts for grievous economic losses. Therefore, a rapid on-site detection and diagnostic technique for this pathogen is in urgent need. In this study, two mouse monoclonal antibodies (MAbs) against V. anguillarum, 6B3-C5 and 8G3-B5, were generated by using hybridoma technology and their isotypes were characterized. MAb 6B3-C5 was chosen as the detector antibody and conjugated with quantum dots. Based on MAb 6B3-C5 labeled with quantum dots, a modified dot blot assay was developed for the on-site determination of V. anguillarum. It was found that the method had no cross-reactivity with other than V. anguillarum bacteria. The detection limit (LOD) for V. anguillarum was 1 × 10³ CFU/ml in cultured bacterial suspension samples, which was a 100-fold higher sensitivity than the reported colloidal gold immunochromatographic test strip. When V. anguillarum was mixed with turbot tissue homogenates, the LOD was 1 × 10³ CFU/ml, suggesting that tissue homogenates did not influence the detection capabilities. Preenrichment with the tissue homogenates for 12 h could raise the LOD up to 1 × 10² CFU/ml, confirming the reliability of the method.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.110-110
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• 2010

본 실험에서는 Silicon (001) 기판을 사용하여 silicon 기판상에 modified Stranski-Krastanow(S-K) 방식으로 InAs quantum dot (QD) 을 성장하고 그 위에 InSb layer를 형성하였다. 기판온도 $390^{\circ}$에서 In injection period를 4번 반복하여 제작된 InAs quantum dot layer를 buffer로 사용하였으며, QD layer의 밀도는 $1{\mu}m^2$ 당 600개, height가 $6.2\;{\pm}\;2.0\;nm$, width가 $36.1\;{\pm}\;9.2\;nm$ 정도이다. 성장된 $2.8{\mu}m$ 두께의 InSb film의 특성을 분석해 보면 AFM 상에서의 root mean square (rms) roughness는 5.142nm정도이며, electron mobility는 340 K 에서 $41,352cm^2/Vs$, 1.8 K에서는 $4,215cm^2/Vs$ 정도를 나타내었다. 본 실험에서는 다른 실험과는 달리 InAs QD 을 buffer layer로 사용하였으며, silicon기판도 아무런 처리가 되지 않은 (001)기판을 사용하였으므로 기존의 다른 연구 결과와는 차별성을 가진다. 또한 buffer로 사용된 InAs quantum dot layer의 종류를 한 가지로 고정하고 실험을 하였지만 추후 더욱 다양한 밀도와 크기의 quantum dot layer를 적용시키고, 기존의 다른 논문에서 적용된 방법들을 추가로 적용시켜 본다면 mobility값은 더욱 증가할 것으로 생각된다. 이러한 연구를 통해 값이 싸고 구하기 쉬운 silicon기판상에 silicon에 비하여 더 좋은 특성을 갖는 III-V족 화합물 반도체 소자를 구현 할 수 있을 것으로 생각된다.

• Korean Chemical Engineering Research
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• v.59 no.3
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• pp.450-454
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• 2021

Currently, gamma nuclide analysis is mainly used using inorganic scintillators or semiconductor detectors. These detectors have high resolution but there are less economical, limited in size, and low process ability than plastic scintillators. Therefore, quantum dot-based plastic scintillator was developed using the advantages of the quantum dot nanomaterial and the conventional plastic scintillator. In this study, efficient plastic scintillator was fabricated by adding CdS/ZnS based on the most widely used Cd-based nanomaterial in a polystyrene matrix. In addition, the performance of the commercial plastic scintillator was compared and it was analyzed through radiological measurement experiments. The detection efficiency of fabricated plastic scintillator was higher than commercial plastic scintillator, EJ-200. It is believed that this fabricated plastic scintillator can be used as a radioactivity analyzer in the medical and nuclear facility fields.

• Korean Journal of Optics and Photonics
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• v.32 no.4
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• pp.163-171
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• 2021

Conventional white light-emitting diodes (LEDs) for lighting applications consist of blue LEDs and yellow phosphors, the spectrum of which lacks deep red. To improve the color-rendering characteristics of white LEDs, a red quantum-dot film was applied to the diffuser plate of LED lighting. The mean free paths of the quantum dots and the concentration of the TiO₂ particles in the diffuser plate were adjusted to optimize the optical structure of the lighting. The color-rendering index (CRI) was greater than 90 for most conditions, which demonstrates that adoption of the red quantum-dot film is an effective way for improving the color-rendering properties of conventional white LEDs. The angular dispersion of color coordinates could be removed by utilizing the optical cavity formed between the diffuser plate and the reflector on the bottom of the lighting, where multiple passages of the light through the quantum-dot film reduced the differences in optical path length depending on the viewing angle.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.390-390
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• 2011

급속한 산업의 발달은 심각한 환경오염 및 에너지 문제를 가져왔다. 이를 해결하기 위하여 무한한 에너지원인 태양에너지를 원천으로 하는 친환경 정화소재로서의 광촉매(photocatalyst)를 통하여 인류의 에너지를 확보하는 것에 대한 관심이 급격하게 증가하고 있는 추세이다. 현재 광촉매로 가장 많이 사용되는 $TiO_2$의 경우 뛰어난 광활성에도 불구하고, 상대적으로 넓은 밴드갭(band gap) 으로 인한 가시광 응답성의 부재로 이를 해결하기 위한 많은 연구가 진행되고 있다. 따라서 본 연구에서는 PIII&D (plasma immersion ion implantation & deposition) 장비를 통하여 -60 kV의 펄스 고전압을 인가해 $TiO_2$에 좁은 band gap을 갖는 반도체를 이온주입하여 가시광 응답성을 갖는 양자점 감응(Quantum dot sensitized)형 광촉매를 제작하였다. 이온주입 후 시료의 chemical state와 crystallinity를 확인하기 위하여 X-ray photoelectron spectroscopy와 X-ray diffraction measurement를 이용하여 분석을 수행하였으며, 이러한 공정을 통해 제작된 양자점 감응형 광촉매의 가시광 응답성을 확인하기 위하여 UV/Vis 스펙트럼을 측정하였다. 또한 광촉매의 효율을 확인하기 위해 물 분해 장치(water splitting device) 를 제작하여 수소와 산소를 생성하였다.

• Journal of Advanced Navigation Technology
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• v.17 no.6
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• pp.700-704
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• 2013

Quantum-dot cellular automata(QCA) is a new technology and it is an one of the alternative high performance over existing complementary metal-oxide semi-conductor(CMOS). QCA is nanoscale device and ultra-low power consumption compared with transistor-based technologies, and various circuits using QCA technology have been proposed. Binary-coded decimal(BCD), which represents decimal digits in binary, is mainly used in electronic circuits and Microprocessor, and it is comfortable in conversion operation but many data loss. In this paper, we present an BCD-EXCESS 3 Code converter which can be efficiently used for subtraction and half adjust. The proposed scheme has efficiently designed considering space and time complexities and minimization of noise, and it has been simulated and confirmed.

• Transactions of the Korean hydrogen and new energy society
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• v.32 no.6
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• pp.656-662
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• 2021

For the high efficiencies of quantum dot-sensitized solar cells (QDSCs), it is important to control the severe electron recombination at the interface of photoanode/electrolyte. In this work, we optimize the surface passivation process of ZnS/SiO₂ double overlayers for the enhanced photovoltaic performances of QDSCs. The overlayers of zinc sulfide (ZnS) and SiO₂ are coated on the surface of QD-sensitized photoanode by successive ionic layer adsorption and reaction (SILAR) method, and sol-gel reaction, respectively. In particular, for the sol-gel reaction of SiO₂, the influences of temperature of precursor solution are investigated. By application of SiO₂ overlayers on the ZnS-coated photoanode, the conversion efficiency of QDSCs is increased from 5.04% to 7.35%. The impedance analysis reveals that the electron recombination at the interface of photoanode/electrolyte is obviously reduced by the SiO₂ overlayers.

• Transactions of the Korean hydrogen and new energy society
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• v.32 no.6
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• pp.663-668
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• 2021

For the development of highly efficient quantum dot-sensitized solar cells (QDSCs), it is important to enhance the electrocatalytic activity of the counter electrodes (CEs). Herein, a fabrication process of Cu₂S CEs are optimized for the development highly efficient QDSCs. The surface of brass film is treated with HCl solution to prepare the Cu₂S CEs, and the concentraion as well as the temperature of HCl solution are controlled. It is found that the uniformity for the thickness of prepared Cu₂S CEs is enhanced when the diluted HCl solution is used, compared to the HCl solution of standard concentration. In addition, the electrocatalytic activity of the Cu₂S CEs is also increased with the modificed process, which is confirmed by impedance data and Tafel polarization curves. As a result, the photoconversion efficiency of QDSCs is improved from 4.49% up to 5.73%, when the concentraion and temperature of the HCl treatment are efficiently optimized.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.444-444
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• 2011

Recently, patterned magnetic films and elements attract a wide interest due to their technological potentials in ultrahigh-density magnetic recording and spintronic devices. Among those patterned magnetic structures, magnetic anti-dot patterning induces a strong shape anisotropy in the film, which can control the magnetic properties such as coercivity, permeability, magnetization reversal process, and magneto-resistance. While majority of the previous works have been concentrated on anti-dot arrays with a single magnetic layer, there has been little work on multilayered anti-dot arrays. In this work, we report on study of the magnetic properties of bilayered anti-dot system consisting of upper perforated Co layer of 40 nm and lower continuous Ni layer of 5 nm thick, fabricated by photolithography and wet-etching processes. The magnetic hysteresis (M-H) loops were measured with a superconducting-quantum-interference-device (SQUID) magnetometer (Quantum Design: MPMS). For comparison, investigations on continuous Co thin film and single-layer Co anti-dot arrays were also performed. The magnetic-domain configuration has been measured by using a magnetic force microscope (PSIA: XE-100) equipped with magnetic tips (Nanosensors). An external electromagnet was employed while obtaining the MFM images. The MFM images revealed well-defined periodic domain networks which arise owing to the anisotropies such as magnetic uniaxial anisotropy, configurational anisotropy, etc. The inclusion of holes in a uniform magnetic film and the insertion of a uniform thin Ni layer, drastically affected the coercivity as compared with single Co anti-dot array, without severely affecting the saturation magnetization ($M_s$). The observed changes in the magnetic properties are closely related to the patterning that hinders the domain-wall motion as well as to the magneto-anisotropic bilayer structure.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.541-541
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• 2012

InP quantum dots capped by myristic acid (InP-MA QDs) were synthesized by a typical hot injection method using MA as stablizing agent. The current density across the InP-MA QDs thin film which was fabricated by spin-coating method is about $10^{-4}A/cm^2$ at the electric field of 0.1 MV/cm from I-V measurement on a metal-insulator-metal (MIM) device. The low conductivity of the InP-MA QDs thin film is interpreted as due to the long interdistances among the dots governed by the MA molecules. Therefore, replacing the MA with thioacetic acid (TAA) by biphasic ligand exchange was conducted in order to obtain TAA capped InP QDs (InP-TAA). InP-TAA QDs were designed due to: 1) the TAA is very short molecule; 2) the thiolate groups on the surface of the InP-TAA QDs are expected to undergo condensation reaction upon thermal annealing which connects the QDs within the QD thin film through a very short linker -S-; and 3) TAA provides better passivation to the QDs both in the solution and thin film states which minimizing the effect of surface trapping states.