• 한국위성정보통신학회논문지
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• 제10권1호
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• pp.62-66
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• 2015

본 논문은 디지털 사이니지의 다양한 콘텐츠 유형과 활용범위에 대하여 소개하고 송수신 거리를 늘리기 위하여 기존의 통신 방식을 분석하였다. 디지털 사이니지를 장거리에서 구현하기 위하여 기존의 모듈레이션 기법들을 결합한 하이브리드 모듈레이션 기법을 제안하고 성능을 분석하였다. 그리고 실제 채널에서의 성능을 검증하기 위해 USRP 장비를 이용하여 심벌을 매핑하고 가시광 통신 송수신 모듈로 데이터를 송수신하는 실험을 수행하였다. 기존의 QAM 방식을 이용한 데이터 수신거리와 송수신 파워를 실험을 통하여 확인하였다. 제안된 하이브리드 모듈레이션 기법을 이용한 데이터 수신거리와 송수신 파워가 기존 QAM 방식보다 뛰어남을 보였다.

• 한국통신학회논문지
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• 제37권5A호
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• pp.358-366
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• 2012

LED-ID (Light Emitting Diode - Identification) is one of the key technologies for identification, data transmission, and illumination simultaneously. This is the new paradigm in the identification technology environment. There are many issues are still now challenging to achieve high performance in LED-ID system. Collision issue is one of them. Actually this is the most significant issue in all identification system. LED-ID system also suffers from collision problem. In our system, collision occurs when two or more readers transmit data to tag at the same time or vice versa. There are many anti-collision protocols to resolve this problem; such as: Slotted ALOHA, Basic Frame Slotted ALOHA, Query Tree, Tree Splitting, and Q-Algorithm etc. In this paper, we propose modified Q-Algorithm to resolve collision at tag. The proposed protocol is based on Q-Algorithm and used the information of arrived readers to a tag from neighbor. The information includes transmitting slot number of readers and the number of readers that can be arrived in next slot. Our proposed protocol can reduce the numbers of collision slot and the successful time to identify all readers. In this paper our simulation and theoretical results are presented.

• Bulletin of the Korean Chemical Society
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• 제35권9호
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• pp.2813-2817
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• 2014

A new magnetic semiconductor material was synthesized to enable separation after a liquid-type photocatalysis process. Core@shell-structured $CuFeS_2@TiO_2$ magnetic nanoparticles were prepared by a combination of solvothermal and wet-impregnation methods for photocatalysis applications. The materials obtained were characterized using X-ray diffraction, transmission electron microscopy, ultraviolet-visible, photoluminescence spectroscopy, Brunauer-Emmett-Teller surface area measurements, and cyclic voltammetry. This study confirmed that the light absorption of $CuFeS_2$ was shifted significantly to the visible wavelength compared to pure $TiO_2$. Moreover, the resulting hydrogen production from the photo-splitting methanol/water solution after 10 hours was more than 4 times on the core@shell structured $CuFeS_2@TiO_2$ nanocatalyst than on either pure $TiO_2$ or $CuFeS_2$.

• 전자공학회논문지
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• 제52권11호
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• pp.115-123
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• 2015

적외선 영상은 외광의 밝기에 영향을 적게 받아서 원격 탐사 및 영상 보안 등의 응용에서 활발하게 활용되고 있다. 그러나 안개와 같은 기상 악화상황으로 인하여 해당 적외선 영상의 화질이 크게 저하되는 경우가 빈번하게 발생한다. 칼라 영상의 안개제거 기술이 다양하게 연구되어온 반면 적외선 영상의 안개제거 기술은 상대적으로 관심을 받지 못하고 있다. 본 논문에서는 근적외선 대역 영상에 대하여 적외선 영상의 통계학적 특징을 이용한 안개 제거 알고리즘을 제안한다. 기계학습 기법을 활용하여 전달량을 보정하고 다중 후처리 기법을 적용하여 정확한 전달량을 구하였다. 제안 기술을 이용하여 복원한 적외선 영상이 기존 칼라영상에 기반한 알고리즘을 적외선 영상에 적용하여 얻은 결과보다 화질이 좋다는 것을 확인하였다.

• 한국전기전자재료학회논문지
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• 제35권4호
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• pp.392-397
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• 2022

We present the structural and optical properties of Au@TiO₂ core-shell microsphere structure prepared by a hydrothermal synthesis method. As a way to improve the efficiency of organic solar cells, the Au@TiO₂ core-shell microsphere was synthesized to use the local surface plasmon resonance (LSPR) phenomenon. The synthesized results were confirmed to have the Au@TiO₂ core-shell structure using a high-resolution transmission electron microscopy. An absorption was observed to occur at 527 nm belonging to the visible light region using a visible light spectroscopy, which supports the LSPR phenomenon. We suggest that the Au@TiO₂ core-shell microsphere is highly likely to be applied to organic solar cells including dye-sensitized solar cells. In addition, we expect it to be widely used not only in the energy but also in the bio as well as in the environmental fields.

• 공업화학
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• 제27권5호
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• pp.483-489
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• 2016

본 연구에서 쉽고 빠른 마이크로 조사법을 사용하여 합성한 $Cu_2Se$-그래핀 나노복합체를 광촉매 분해 효과를 연구하였다. 제조된 나노복합체는 XRD, SEM, TEM, 라만분광분석, XPS 및 UV-Vis 흡수분광법을 사용하여 특성화하였다. 그리고 광촉매 분해특성을 가시광선 조사하에 표준염료인 로다민 B의 분해를 통하여 연구하였다. $Cu_2Se$-그래핀 복합체는 상당히 우수한 광촉매 분해 효과를 나타내었고, 이는 180 min 동안 가시광선 조사하에서 약 95%의 분해 효과를 나타내고 있음을 이들 결과로부터 알 수 있었다. 결론적으로 $Cu_2Se$-그래핀 복합체는 염료 오염물질에 대한 적합한 촉매로 사용할 수 있음을 확인하였다.

• 한국태양에너지학회:학술대회논문집
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• 한국태양에너지학회 2011년도 춘계학술발표대회 논문집
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• pp.31-35
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• 2011

Photovoltaic modules are well known to be one of the most eco generation of electricity. But usually study solar cell. Otherwise, PV modules are also important in power generation. We have to check other subsidiary materials. In this work benefit of using optically superior encapsulation materials(EVA) in generation temperature is demonstrated. Optical characterization of three EVA products demonstrates reduced transmission in the visible ray region of the solar spectrum. It will have a decisive effect to the module efficiency. Test is shown reduction of reflectance and transmittance. Reflections is dependent on the low iron glass. It can be seen between a specific wave length(240~350mm) about 1%. Transmittance in the entire ray region of light is markedly reduced to depending on the temperature rise. The graph is shown optical properties on EVA. Transmission was reduced. about 1%.

• 한국전자통신학회논문지
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• 제15권1호
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• pp.39-44
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• 2020

유리기판위에 스퍼터링법으로 비정질 BaTiO₃막을 증착시켰다. 증착된 BaTiO₃ 막을 코로나 폴링을 하여 광학적 특성을 조사하였다. 가시광영역에서 투과율은 80% 이상으로 좋았으며, 비선형광학 특성은 폴링 조건에 따라 영향을 받으며, 크기는 1.15pm/V였다. 장기특성도 한달이 지나도 60%이상 유지하였다. 또한 BaTiO₃ 박막으로부터 녹색광 발생을 확인하였다.

• 한국세라믹학회지
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• 제41권5호
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• pp.364-369
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• 2004

The barrier and optical properties of AlO$_{x}$ thin films on polycarbonate deposited by Reactive Ion Beam Sputtering (RIBS) were investigated at different oxygen partial pressure. We measured the deposition rate of AlO$_{x}$ thin films. As the oxygen partial pres-sure increased, the deposition rate increased then decreased. The changes of deposition rate are associated with the properties of deposited films. The properties of deposited AlO$_{x}$ thin films were studied using X-ray Photoelectron Spectroscopy (XPS), Scan-ning Electron Microscopy (SEM), and Atomic Force Microscopy (AFM). Optimum deposition parameters were found for fabricat-ing aluminum oxide thin films with high optical transparency for visible light and low Oxygen Transmission Rate (OTR). The optical transmittance of AlO$_{x}$ thin film deposited on polycarbonate (PC) showed the same value of bare PC.bare PC.

• 한국세라믹학회지
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• 제54권1호
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• pp.28-32
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• 2017

The degradation of methyl blue (MB) catalyzed by platinum (Pt)-graphene/$TiO_2$ in dark ambiance was studied. Pt-graphene/$TiO_2$ composites were prepared by simple hydrothermal method. Characterizations of composites were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), specific surface area (BET) analysis, and energy dispersive X-ray (EDX) analysis. UV-spectroscopic analysis of the dyes was performed by measuring the change in absorbance. The degradation of the organic dyes was calculated based on the decrease in concentration of the dyes with respect to regular time intervals. Rate coefficients for the catalytic process were successfully established and reusability tests were performed to test the stability of the used catalysts.