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Calcite 필러를 함유한 유리 복합체의 표면형상과 반사율
전재승,황성진,안지환,김형순,Jeon, Jae-Seung,Hwang, Seong-Jin,Ahn, Ji-Hwan,Kim, Hyung-Sun 한국재료학회 2009 한국재료학회지 Vol.19 No.8
Reflection properties, such as specular reflection and diffuse reflection, are very important optical properties for the reflector, which has high reflectance in the display and architecture industry. Calcite is lowcost, nontoxic, and stable over a wide temperature range. Therefore, it is one of the most widely using fillers in many industries and has some advantages over titania as a filler to improve reflectance. However, optical properties, especially those of ceramic-filled composites, have not been analyzed. We studied the reflectance of calcite composites with their surface roughness. The reflectance of the composites was determined using a UV-visible spectrometer. The surface morphology and the micro-structure of the composites were investigated by atomic force microscope. The reflectance of the composites was improved by increasing the content of calcite in the calcite-frit composite. The reflectance is related with the surface roughness in the composites. However, the reflectance depends on the calcite contents in materials with similar surface roughness.
V-groove 박판의 FCAW와 EGW 공정에 따른 변형에 미치는 공정인자 영향
한주호,전재승,박철성,오종인,윤진오,이정수,Han, Juho,Jeon, Jaeseung,Park, Chulsung,Oh, Chongin,Yun, Jinoh,Lee, Jeongsoo 대한용접접합학회 2013 대한용접·접합학회지 Vol.31 No.1
Finite element analysis and welding experiments were performed to evaluate deformation aspect for Flux Cored Arc Welding(FCAW) and Electro Gas Welding(EGW). Numerical researches of FCAW and EGW were performed considering the difference of number of welding pass and welding direction to arc flow. To perform the numerical study of FCAW and EGW, number of welding pass and welding direction to arc flow were considered in the finite element model. FCAW process requires multi pass and its welding direction is vertical to welding torch. On the other hand, EGW process requires single pass and its welding direction is parallel to welding torch. The difference of welding direction and heat input was considered in the finite element analysis. In FCAW process, Goldak's double ellipsoidal heat input model was adopted. In the EGW process, Hemi-spherical power density distribution was adopted. In the results of experiment and finite element analysis, angular deformation of FCAW process is larger than that of EGW process.
Effect of Glass Frit in TiO<sub>2</sub> Electrode for DSSCs
김종우(Kim, Jongwoo),전재승(Jeon, Jaeseung),김동선(Kim, Dongsun),황성진(Hwang, Seongjin),김형순(Kim, Hyungsun) 한국신재생에너지학회 2010 한국신재생에너지학회 학술대회논문집 Vol.2010 No.06
Dye sensitized solar cells(DSSCs) have been extensively studied due to their various advantages such as low production cost, colorful design, and eco-friendly process. Long optical path length is one of the most effective method to improve light harvest efficiency for DSSCs. Multi-layered TiO₂ nano-structured film with scattering layer has been studied to generate scattering effect by many researchers. It was expected that the difference of refractive index between TiO₂ particles and glass frit would generate the light scattering effect and provide the long optical path length. Therefore, to enhance the scattering effect, the frits of Bi₂O₃-B₂O₃-ZnO glass system that has the different refractive index were added to TiO₂ pastes in this study. First of all, the absorbance and haze factor of TiO₂ electrode with dyes and the refractive index of glass frit and TiO₂ were measured, respectively. To study the effect of frits, the efficiencies of DSSCs added glass frit and without glass frit were compared. Our results showed slightly higher efficiency with the different absorbance and haze factor of TiO₂ and glass frit. It was considered that the light scattering effect would be improved with adding frits to TiO₂ paste. Our preliminary studies will be useful for increasing efficiency of DSSCs.
황성진(Hwang, Seongjin),정현상(Jung, Hyunsang),전재승(Jeon, Jaeseung),김형순(Kim, Hyungsun) 한국신재생에너지학회 2010 한국신재생에너지학회 학술대회논문집 Vol.2010 No.06
Dye-sensitized solar cells (DSSC) show great promise as an inexpensive alternative to conventional p-n junction solar cells. Investigations into the various factors influencing the photovoltaic efficiency have recently been intensified. The conventional absorber electrode in DSSC is composed of compacted or sintered TiO₂ nanopowder that carries an anchored organic dye. The absorbance of incident light in the DSC is realized by specifically engineered dye molecules placed on the semiconductor electrode surface (TiO₂). The dye absorbs light at wavelengths up to about 920nm, the energy of the exited state of the molecule should be about 1.35eV above the electronic ground state corresponding to the ideal band gap of a single band gap solar cell. The dye molecules ar adhered onto the nanostrutured TiO₂ electrode by immersing the sintered electrode into a dye solution, typically 3mM in alcohol, for a long enough period to fully impregnate the electrode. However, the concentrations of the dye is slightly changed due to the evaporation of the alcohol. The dye is more expensive than other materials in DSSC and related to the efficiency of DSSC. Therefore, the concentrations of the dye should be carefully measured. In this study, we investigated to the dye loading on fired TiO₂ powder as a function of temperature by the TG-DTA and the dye solution by UV-visible spectroscopy after the impregnation process. The dye loading is related to the porosity of the nanostructured TiO₂ electrode.