$Cu_2SnSe_3$ (CTSe) and $Cu_2ZnSnSe_4$ (CZTSe) nanoparticles were synthesized by sonochemical reactions under multibubble sonoluminescence (MBSL) conditions. First, $Cu_2SnSe_3$ nanoparticles were synthesized by the sonochemical method with an 85% yield, using CuCl, $SnCl_2$, and Se. Second, ZnSe was coated on the CTSe nanoparticles by the same method. Then, they were transformed into CZTSe nanoparticles of 5-7 nm diameters by heating them at $500^{\circ}C$ for 1 h. The ratios between Zn and Sn could be controlled from 1 to 3.75 by adjusting the relative concentrations of CTSe and ZnSe. With relatively lower Zn:Sn ratios (0.75-1.26), there are mostly CZTSe nanoparticles but they are believed to include very small amount of CTS and ZnSe particles. The prepared nanoparticles show different band gaps from 1.36 to 1.47 eV depending on the Zn/Sn ratios. In this sonochemical method without using any toxic or high temperature solvents, the specific stoichiometric element Zn/Sn ratios in CZTSe were controllable on demand and their experimental results were always reproducible in separate syntheses. The CZTSe nanoparticles were investigated by using X-ray diffractometer, a UV-Vis spectrophotometer, scanning electron microscope, Raman spectroscopy, and a high resolution-transmission electron microscope.
The test on the mix of PVA fiber of low carbon inorganic composite as a cement substitute found it to be satisfactory in terms of flexibility and stiffness. The result of the evaluation of the properties of low carbon inorganic panel revealed that the absorptivity was low at 8 to 9%, which is lower than the KS value of 25%. Also, the test on non-combustibility and gas toxicity found that these factors satisfied the decision criteria. In the test on heavy metals discharges, Pb, Cd, Cr6+, Hg, and As were not detected. Regarding far-Infrared emissivity and formaldehyde emission, the substitute was found to be harmless to the human body. Therefore, if the issue of shrinkage, which is a disadvantage of inorganic composites, is addressed, it is judged that it is possible to develop a low carbon inorganic composite panel with better performance.
The insulation in buildings is very important. Insulation used in the building is largely divided into organic and inorganic insulation by its insulation material. Organic insulation materials which are made of Styrofoam or polyurethane are extremely vulnerable to fire. On the other hand, inorganic insulation such as mineral wool and glass wool is very weak with moisture, while it is nonflammable, so that its usage is very limited. Therefore, this study developed moisture resistance applicable to mineral wool and glass wool and measured the thermal conductivity of the samples which are exposed to moisture by exposing the product coated with moisture resistance and without moisture resistance to moisture and evaluated how the moisture affects thermal conductivity by applying this to inorganic insulation.
본 연구에서는 불연성 무기단열재를 제조하기 위해 바인더 종류를 대체하여 열전도율을 충족시키고 경량 무기단열재 개발을 위해 연구하였다. 열전도율 측정은 열전도 측정기인 HFM-436을 이용하여 열전도율을 측정하였다. 무기단열재를 바인더 SH-1(액체), SH-2(고체)와 펄라이트를 배합하여 단열재 샘플1을 만들었고, SH-3(액체)와 펄라이트를 배합하여 단열재 샘플 2를 제조했다. 총 4개의 샘플을 제조했다. 각각 바인더와 펄라이트를 틀에 넣어 성형하였으며 완전건조 후 HFM-435을 이용하여 열전도율을 측정하였다. 두 가지 다른 바인더를 사용하여 열전도율을 측정하였고 바인더에 따른 열전도율의 영향을 분석하였다. In this study, we conducted about the manufacture of a non-combustible inorganic insulation by replacing the binder type for satisfaction of thermal conductivity for developing a lightweight inorganic insulation. Thermal conductivity was measured using a machine of HFM-436. We made samples are inorganic insulation by using SH-1(liquid) of S company and SH-2(solids). By Mixing Pearlite and SH-4(Liquid) was produced as insulation sample 2. Each was shaped into a binder and pearlite in the frame. After complete drying, thermal conductivity was measured by using HFM-435. The thermal conductivity was determined using two different binder. We analyzed the effect on thermal conductivity in binder.
수소 플라즈마를 작동유체로 사용하는 헬리컬형 MHD 발전기의 유동-전자기장 특성 및 성능을 평가하기 위해 수치해석을 수행하였다. 자기장을 인가하지 않은 단순 유동해석 결과에서 헬리컬 회전수가 2회이고, 유동유도기/정류기가 없는 Model-A-1이 MHD부 유속이 가장 높게 평가되었다. 이에 따라 Model-A-1에 대해서 유동-전자기장 연계해석을 수행하였다. 유동-전자기장 연계해석 결과로부터 인출 가능한 출력은 입구 압력 높고 자기장 세기가 클수록 크게 평가되었으며, 발전 효율은 입구 압력이 낮을수록 높게 평가되었다. 헬리컬형 MHD 발전기의 최대 인출 가능한 출력 및 효율은 서로 다른 해석조건에서 각각 1.13 MW와 15.9%로 평가되었다.
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