• Journal of electromagnetic engineering and science
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• 제5권4호
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• pp.183-188
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• 2005

A simple microwave backscattering model for vegetation canopies on earth surfaces is developed in this study. A natural earth surface is modeled as a two-layer structure comprising a vegetation layer and a ground layer. This scattering model includes various scattering mechanisms up to the first-order multiple scattering( double-bounce scattering). Radar backscatter from ground surface has been modeled by the polarimetric semi-empirical model (PSEM), while the backscatter from the vegetation layer modeled by the vector radiative transfer model. The vegetation layer is modeled by random distribution of mixed scattering particles, such as leaves, branches and trunks. The number of input parameters has been minimized to simplify the scattering model. The computation results are compared with the experimental measurements, which were obtained by ground-based scatterometers and NASA/JPL air-borne synthetic aperture radar(SAR) system. It was found that the scattering model agrees well with the experimental data, even though the model used only ten input parameters.

• 한국분말재료학회지
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• 제16권5호
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• pp.305-309
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• 2009

The effect of light scattering layers (400 nm, TiO$_2$ particle) of 4 $\mu$m thickness on the dye-sensitized solar cell has been investigated with a 12 $\mu$m thickness of photo-anode (20 nm, TiO$_2$ particle). Two different structures of scattering layers (separated and back) were applied to investigate the light transmitting behaviors and solar cell properties. The light transmittance and cell efficiency significantly improved with inserting scattering layers. The back scattering layer structure had more effective transmitting behavior, but separated scattering layer (center: 2 $\mu$m, back: 2 $\mu$m) structure (9.83% of efficiency) showing higher efficiency (0.6%), short circuit current density (0.26 mA/cm$^2$) and fill factor (0.02). The inserting separating two scattering layers improved the light harvesting, and relatively thin back scattering layer (2 $\mu$m of thickness) minimized interruption of ion diffusion in liquid electrolyte.

• 한국전기전자재료학회논문지
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• 제25권7호
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• pp.558-562
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• 2012

As an alternative energy, Dye-sensitized solar cells (DSSCs) have received much attention due to low cost manufacturing procedure and high energy consumption rate. Incorporating scattering centers in the nanocrystalline photoanode or additional scattering layers on the nanocrystalline photoanode is an effective way to enhance the light harvest efficiency of the photoanode and the performance of dye-sensitized solar cells (DSSCs). The light scattering abilities of these scattering layers also depend on the relative sizes and phase of the particles in the layers. A higher surface area is normally obtained using large particle sizes. Therefore, transparent high surface area $TiO_2$ layers and an additional scattering layer consisting of $TiO_2$-Rutile 500 nm paste with relatively larger particles are attractive. In this work, we investigates the applicability of a hybrid $TiO_2$ electrode (or a working electrode with a light scattering layer) in a DSSCs. We fabrication various thin film using $TiO_2$ paste 20 nm and $TiO_2$ paste 500 nm. As a result, the efficiency of the a single structure thin film was 3.35% and the efficiency as scattering layer of hybrid structure thin film was 4.36%, 4.73%.

• Bulletin of the Korean Chemical Society
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• 제33권9호
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• pp.3043-3047
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• 2012

To investigate the scattering layer effect of a $TiO_2$ multilayer in dye-sensitized solar cells (DSSCs), we designed a new DSSC system, assembled with a CdS-$TiO_2$ scattering layer electrode. A high-magnification SEM image exhibited hollyhock-like particles with a width of 1.5-2.0 ${\mu}m$ that were aggregated into 10-nm clumps in a hexagonal petal shape. The efficiency was higher in the DSSC assembled with a CdS-$TiO_2$ scattering layer than in the DSSC assembled with $TiO_2$-only layers, due to the decreased resistance in electrochemical impedance spectroscopy (EIS). The short-circuit current density ($J_{sc}$) was increased by approximately 7.26% and the open-circuit voltage ($V_{oc}$) by 2.44% over the 1.0 wt % CdS-$TiO_2$ composite scattering layer and the incident photon-to-current conversion efficiency (IPCE) in the maximum peak was also enhanced by about 5.0%, compared to the DSSC assembled without the CdS-$TiO_2$scattering layer.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2011년도 제42회 하계학술대회
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• pp.1503-1504
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• 2011

염료 감응형 태양전지(Dye-sensitized Solar Cells, DSC)에서 고효율화를 위해 light scattering layer가 반도체 산화물 $TiO_2$와 함께 많이 사용되고 있다. 이것은 light scattering layer에 의해 빛의 이용률을 증가시킴으로써 DSC의 성능을 증대 시킬 수 있기 때문이다. 따라서 본 연구에서는 입자크기가 크고 반사율이 좋은 $Nb_2O_5$를 light scattering layer로 사용하여 $TiO_2$ layer를 통과한 빛을 다시 반사시켜 빛의 이용률을 증대시킴으로써 DSC 성능면에서 light scattering layer를 사용하지 않았을 때보다 전류밀도와 효율을 크게 증가시키고자 하였다. 그 결과 $V_{OC}$는 0.74V, $J_{SC}$는 17.95mA/$cm^2$, FF는 0.63, ${\Box}$는 8.38%로 기존의 DSC 보다 전류밀도가 약 30%, 효율이 약 31% 증가한 좋은 결과를 얻을 수 있었다.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2008년도 추계학술대회 논문집
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• pp.128-130
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• 2008

One of methods to increase the efficiency of a dye-sensitized solar cell(DSC) is the effective usage of the incident light. It can be controlled by using a light scattering layer. The light scattering effect makes that the optical path length of incident light to DSC increases. And then, the photocurrent and the efficiency is increased because of the increase of dye adsorption and the abundant amount of the light. In this study, we apply the light scattering layer to DSC by using two $TiO_2$ pastes that have different particle sizes. As a result, the photocurrent increases and the total efficiency is also increases in the case of using large-sized $TiO_2$ particle as the light scattering layer.

• 수산해양기술연구
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• 제46권4호
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• pp.449-457
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• 2010

This study shows that the vertical migration speed of sound scattering layers (SSLs), which is distributed in near Funka Bay, were measured by 3D velocity components acquired from a bottom moorng ADCP. While the bottom mooring type has a problem to measure the velocity vectors of sound scattering layer distributed near to surface, both the continuous vertical migration patterns and variability of backscatterers were routinely investigated as well. In addition, the velocity vectors were compared with the vertical migration velocity estimated from echograms of Mean Volume Backscattering Strength, and estimated to produce observational bias due to SSLs which is composed of backscatterers such as euphausiids, nekton, and fishes have swimming ability.

• 대한전자공학회논문지SD
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• 제45권4호
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• pp.57-63
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• 2008

본 논문에서는 Contact Etch Stop Layer (CESL)인 nitride film의 mechanical stress에 의해 인가되는 channel stress가 소자 특성에 미치는 영향에 대해 분석하였다. 잘 알려진 바와 같이 NMOS는 tensile stress와 PMOS에서는 compressive stress가 인가되었을 경우 drain current가 증가하였으며 그 원인을 체계적으로 분석하였다. NMOS의 경우 tensile stress가 인가됨으로써 back scattering ratio ($\tau_{sat}$)의 감소와 thermal injection velocity ($V_{inj}$)의 증가로 인해 mobility가 개선됨을 확인하였다. 또한 $\tau_{sat}$, 의 감소는 온도에 따른 mobility의 감소율이 작고, 그에 따른 mean free path ($\lambda_O$)의 감소율이 작기 때문인 것으로 확인되었다. 한편 PMOS의 compressive stress 경우에는 tensile stress에 비해 온도에 따른 mobility의 감소율이 크기 때문에 channel back scattering 현상은 심해지지만 source에서의 $V_{inj}$가 큰 폭으로 증가함으로써 mobility가 개선됨을 확인 할 수 있었다. 따라서 CES-Layer에 의해 인가된 channel stress에 따른 소자 특성의 변화는 inversion layer에서의 channel back scattering 현상과 source에서의 thermal injection velocity에 매우 의존함을 알 수 있다.

• Bulletin of the Korean Chemical Society
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• 제33권2호
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• pp.469-472
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• 2012

Intensity modulated photocurrent spectroscopy and intensity modulated photovoltage spectroscopy were investigated to measure the dynamic response of charge transfer and recombination in the standard, $TiCl_4$-treated and the combined scattering layer electrode dye-sensitized solar cells (DSSCs). IMPS and IMVS provided transit time ($\tau_n$), lifetime ($\tau_r$), diffusion coefficient ($D_n$) and effective diffusion length ($L_n$). These expressions are derived that generation, collection, and recombination of electrons in a thin layer nanocrystalline DSSC under conditions of steady illumination and with a superimposed small amplitude modulation. In this experimental, IMPS/IMVS showed that the main effect of $TiCl_4$ treatment is to suppress the recombination of photogenerated electrons, thereby extending their lifetime. And the Diffusion coefficient of combined scattering layer electrode is $6.10{\times}10^{-6}$ higher than that of the others, resulting in longer diffusion length.

• Bulletin of the Korean Chemical Society
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• 제35권4호
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• pp.1165-1168
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• 2014

We prepared dye-sensitized solar cells (DSSCs) with enhanced energy conversion efficiency using open-ended $TiO_2$ nanotube arrays with a $TiO_2$ scattering layer. As compared to closed-ended $TiO_2$ nanotube arrays, the energy conversion efficiency of the open-ended $TiO_2$ nanotube arrays was increased from 5.63% to 5.92%, which is an enhancement of 5.15%. With the $TiO_2$ scattering layer, the energy conversion efficiency was increased from 5.92% to 6.53%, which is an enhancement of 10.30%. After treating the open-ended $TiO_2$ nanotube arrays with $TiCl_4$, the energy conversion efficiency was increased from 6.53% to 6.89%, a 5.51% enhancement, which is attributed to improved light harvesting and increased dye adsorption.