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pISSN : 1225-1429 / eISSN : 2234-5078

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2011, Vol.21, No.6

  • 1.

    A study on the surface characteristics of diamond wire-sawn silicon wafer for photovoltaic application

    Kyoung-Hee Lee | 2011, 21(6) | pp.225~229 | number of Cited : 4
    Abstract PDF
    Most of the silicon cutting methods using the multi-wire with the slurry injection have been used for wafers of the crystalline solar cell. But the productivity of slurry injection cutting type falls due to low cutting speeds. Also, the direct contact with the metal wire and silicon block increases the concentration of metallic impurities in the wafer’s surface. In addition, the abrasive silicon carbide (SiC) generates pollutants. And production costs are rising because it does not re-use the worn wire. On the other hand, the productivity of the cutting method using the diamond coated wire is about 2 times faster than the slurry injection cutting type. Also, the continuous cutting using the used wire of low wear is possible. And this is a big advantage for reduced production costs. Therefore, the cutting method of the diamond coated wire is more efficient than the slurry injection cutting technique. In this study, each cutting type is analyzed using the surface characteristics of the solar wafer and will describe the effects of the manufacturing process of the solar cell. Finally, we will suggest improvement methods of the solar cell process for using the diamond cutting type wafer.
  • 2.

    Fluorine-based inductively coupled plasma etching of ZnO film

    박종천 | BYEONG WOO LEE | KIM BYUNG IK and 1other persons | 2011, 21(6) | pp.230~234 | number of Cited : 3
    Abstract PDF
    High density plasma etching of ZnO film was performed in CF4/Ar and SF6/Ar inductively coupled plasmas. Maximum etch rates of ~1950 Å/min and ~1400 Å/min were obtained for 10CF4/5Ar and 10SF6/5Ar ICP discharges,respectively. The etched ZnO surfaces showed better RMS roughness values than the unetched control sample under most of the conditions examined. In the 10CF4/5Ar ICP discharges, very high etch selectivities were obtained for ZnO over Ni (max. 11) while Al showed etch selectivities in the range of 1.6~4.7 to ZnO.
  • 3.

    The effect of TiCrN coating on high temperature stability of Inconel 617

    BYEONG WOO LEE | 박종천 | 김미루 and 3other persons | 2011, 21(6) | pp.235~239 | number of Cited : 2
    Abstract PDF
    TiCrN layers (Ti : Cr = 20 : 80 and 5 : 95 wt%) were deposited on Inconel 617 and the effect of TiCrN coating on the high temperature stability of Inconel 617 up to 1000oC was examined. XRD analysis and microstructural observation showed that vigorous and inhomogenous Cr diffusion to the surface was suppressed by TiCrN layer compare to the uncoated Inconel 617. This led to a distinctive enhancement in thermal oxidation resistance of Inconel 617.
  • 4.

    Intercalation behavior study of ibuprofen/clay organic-inorganic nanocomposites as drug release system

    최봉석 | 김동현 | Taewan Kim and 3other persons | 2011, 21(6) | pp.240~245 | number of Cited : 0
    Abstract PDF
    This research focused on the intercalation behavior of recrystallized ibuprofen into clay as a sustained release drug carrier. The intercalation behaviors of ibuprofen were determined by X-ray diffraction (XRD) and thermogravimetric analysis (TGA). The basal spacing (d001) of clay increased from 1.2 nm to 1.5 nm by ibuprofen molecules. The segmental motion effect of ibuprofen into the clay interlayer spacing also increased the thermal stability of the ibuprofen/clay nanocomposites. The in vitro drug release results of nanocomposites showed that ibuprofen was released from clay steadily.
  • 5.

    Fabrication and characterization of Mn-Si thermoelectric materials by mechanical alloying

    Lee Chung-Hyo | 2011, 21(6) | pp.246~252 | number of Cited : 6
    Abstract PDF
    The semiconducting MnSi1.73 compound has been recognized as a thermoelectric material with excellent oxidation resistance and stable characteristics at elevated temperature. In the present work, we applied mechanical alloying (MA)technique to produce MnSi1.73 compound using a mixture of elemental manganese and silicon powders. The mechanical alloying was carried out using a Fritsch P-5 planetary mill under Ar gas atmosphere. The MA powders were characterized by the X-ray diffraction with Cu-Kα radiation, thermal analysis and scanning electron microscopy. Due to the observed larger loss of Si relative to Mn during mechanical alloying of MnSi1.73, the starting composition of a mixture Mn-Si was modified to MnSi1.83 and then MnSi1.88. The single MnSi1.73 phase has been obtained by mechanical alloying of MnSi1.88mixture powders for 200 hours. It is also found that the grain size of MnSi1.73 compound powders analyzed by Hall plot method is reduced to 40 nm after 200 hours of milling.
  • 6.

    Numerical analysis for electro-mechanical coupling performance of 1-3 type Piezo-composite

    신호용 | 김종호 | 임수진 and 1other persons | 2011, 21(6) | pp.253~258 | number of Cited : 0
    Abstract PDF
    Electro-mechanical coupling performance (kt) of a 1-3 type Piezo-composite was analyzed numerically using FEM. The calculated physical properties of the PZT ceramics were compared with the experimental data and the accuracy of the numerical method was verified. Also the kt of the composite was analyzed with the vol% and the material properties of the constitutional parts, and the aspect ratio of the PZT rod. As the simulated results, the kt increased rapidly when the vol% of the PZT ceramics increased up to 30 vol% and saturated the constant value in the above region. And the composite using the soft matrix polymer than the hard one have the superior kt characteristics. The kt was greatly influenced by the aspect ratio of the PZT rod up to 30 vol% of PZT ceramics. To improve the kt characteristics, it is useful that the composite consist of the relatively flexible polymers and the PZT material having the excellent piezoelectric characteristics.
  • 7.

    The sintering characteristics of fly ash-clay system with mine tailing

    Kim Kyung Nam | 우동명 | Hyun Park | 2011, 21(6) | pp.259~265 | number of Cited : 2
    Abstract PDF
    This research was performed to stabilize heavy metals in mine tailing using fly ash and clay. Fly ash-clay-mine tailing system were investigated using XRD (X-ray diffractometer), XRF (X-ray fluorescence spectrometer), TG-DTA, SEM (Scanning Electron Microscope), Dilatometer and UTM with various mine tailing contents (~15 wt%). The fly ash used in this research was mainly composed of SiO2 (33.01 wt%), Al2O3 (28.54 wt%), K2O (3.32 wt%), Fe2O3 (1.47 wt%), CaO (9.97 wt%). SiO2 and Al2O3 composition of the clay was over 61 wt%. And the mine tailing have high composition of SiO2(26.91 wt%), CaO (24.25 wt%), Fe2O3 (22.97 wt%). Therefore, it was estimated that fly ash-clay-mine tailing have enough sintering characteristics. The shrinkage of specimens started at around 850oC and changed little up to 1100oC, but increased markedly at above 1100oC. The shrinkage rate is strongly related to the decarbonization amount of coal fly ash. As the result of SEM, structure of the specimens with mine tailing addition showed more close than the one without mine tailing. Compressive strength of the specimens with mine tailing was highly increased to approximately 200~420 kgf/cm2, it satisfied the first grade criterion for clay brick by KS L 4201. The specification of leaching characteristics of the sintered specimens were within the Korean regulation standard.
  • 8.

    A study on the fabrication of foamed glass by using refused coal ore and its physical properties

    임태영 | 구현우 | Jonghee Hwang and 2other persons | 2011, 21(6) | pp.266~273 | number of Cited : 2
    Abstract PDF
    Foamed glass was fabricated by using glass powder and foaming agents. For the glass powder, we used sodalime glass which’s manufactured by using refused coal ore obtained as by-product from Dogye coal mine in Samcheok. And for the foaming agents, we used Calcium carbonate, Calcium phosphate and powder of shale type refused coal ore itself which has high content of carbon materials. We additionally used liquid binder for forming, and mixed together. And we formed rectangular shape and treated 800oC for 20 min in an electrical furnace. The various kinds of foam glass samples were fabricated according to the kinds of foaming agents. The physical properties of samples, as specific gravity and compressive strength, were measured. Pore structure of each samples were investigated too. Foam glass with specific gravity of 0.4~0.7 and compressive strength of 30~72 kg/cm2. Especially we get satisfying foam glass sample with low specific gravity of 0.47 and high compressive strength of 72 kg/cm2 by the use of liquid calcium phosphate as foaming agent. It also had small and even shape of pore structure. Therefore, it is concluded that refused coal ore can be used for raw materials to manufacture secondary glass products such as a foamed glass panel for construction and industrial materials.
  • 9.

    Characterization of bromine and chlorine in the closed combustion system

    최기인 | 권덕준 | 배성진 and 1other persons | 2011, 21(6) | pp.274~279 | number of Cited : 0
    Abstract PDF
    In this study, we investigated the analytical methods for bromine (Br) and chloride (Cl) with oxygen combustion bomb, using a halogen-containing polymer materials. On measuring Cl content, it showed less reproducibility of the results applying Mohr method or potentiometric titration method than those applying acid-base titration method. In both Br and Cl tests with an oxygen combustion bomb, their concentrations in the absorption and cleaning solution with distilled water were much higher than those in the combustion gas. On the other hand, the concentration level of Br measured by the oxygen combustion bomb method were a little bit lower than those measured by XRF or combustionion chromatography.