Korean | English

pISSN : 1225-1429 / eISSN : 2234-5078

2020 KCI Impact Factor : 0.17
Home > Explore Content > All Issues > Article List

2013, Vol.23, No.2

  • 1.

    Numerical analysis of sapphire crystal growth process using Ky and CZ method

    신호용 | 임지현 | IM JONG IN | 2013, 23(2) | pp.59~66 | number of Cited : 4
    Abstract PDF
    Sapphire crystals are used in a substrate of the LED devices. Both Kyropoulos (Ky) and Czochralski (CZ)growth process are widely applied techniques for growing high quality sapphire single crystal. A successful growth of the sapphire crystals requires the control of heat and mass transport phenomena. In this study, the growth processes of the sapphire crystal using the resistivity-heated Ky method and the inductively-heated CZ method have been analyzed numerically using finite element method. Based on the simulation results, the melt-crystal interface of the crystal changed from the concave to the flat shape as the Ky process progressed. In case of the CZ method, the high temperature positions moved from the crucible surface to inside the melt and the interface changed to the flat shape when the RPM was increased. Also the interface shape of the grown crystal has been influenced by the formed shoulder shape at the initial stage.
  • 2.

    Design optimization of the outlet holes for bone crystal growing with bioactive materials in dental implants: Part I. cross-sectional area

    이용근 | 이강수 | 2013, 23(2) | pp.67~75 | number of Cited : 0
    Abstract PDF
    In order to improve osseo-integration of a dental implant with bone crystal we studied an implant with holes inside its body to deliver bioactive materials based on a proposed patent. After bioactive material is absorbed, bone crystal can grow into holes to increase implant bonding in addition to surface integration. The larger cross section area of outlet holes showed the less values of the maximum stress, and the stress concentrations near the uppermost outlet holes were also reduced with an increasing number of outlet holes. The conclusion, that the uppermost outlet design improvement was most effective to reduce the stress concentration and improve the growth rate of bone crystal, could be drawn. After the design optimizations, Type 6-C had provided the best results in this study. The overall shape optimization studies on the shape, location, number, and so on, of the outlet holes, should be carried out further.
  • 3.

    Design optimization of the outlet holes for bone crystal growing with bioactive materials in dental implants: Part II. number and shapes

    이강수 | Geug-Tae Kim | 이용근 | 2013, 23(2) | pp.76~80 | number of Cited : 0
    Abstract PDF
    For further improvement of osseo-integration of bone crystal with a dental implant, a design optimization study is carried out for various holes inside its body to deliver bioactive materials and the effect of bioactive material injection on the bone crystal growing. When bioactive material is absorbed, the bone crystal can grow into holes, which would increase the strength of implant bonding as well as a surface integration. The stress concentrations near the uppermost outlet holes were reduced with increasing the number of outlet holes. A design improvement in the uppermost outlet was shown to be effective in reducing the stress concentration. For design parameters under consideration in this study, total area of outlet of 6.38 mm2 and maximum stress of 1.114 MPa, which corresponds to type 6-C. It is due to the minimization of maximum stress and total area of outlet. The design of the outlet facing down was more effective in reducing the maximum stress value compared with a horizontal symmetry.
  • 4.

    Properties of colored topaz by new surface treatment

    이보현 | 구창식 | YON SEOG JOO and 3other persons | 2013, 23(2) | pp.81~85 | number of Cited : 0
    Abstract PDF
    We performed analysis of composition and structure of coating layers by using ED-XRF and TOF-SIMS for some passion topaz of Swarovski which developed recently as new surface treatment of TCF (thermal color fusion)technique. In addition, we compared differences between Ti-coated topaz (Mystic topaz) and new treated colored topazes (passion topaz) with magnification observation and simplified durability test. As a result, we can observe similar characteristic clues in Ti-coated topaz and passion topaz by magnified observation. According to results of depth profile by TOF-SIMS, we can know that topaz is treated by multi-layer coating or surface diffusion coating. Moreover, the passion topaz which is treated by chemical reaction between metal elements shows more stable chemical resistance and higher Mohs’ hardness than Ti-coated topaz.
  • 5.

    Silicon surface texturing for enhanced nanocrystalline diamond seeding efficiency

    박종천 | 정옥근 | 김상윤 and 3other persons | 2013, 23(2) | pp.86~92 | number of Cited : 3
    Abstract PDF
    SF6/O2 inductively coupled plasmas were employed to texture Si surface as a pretreatment for nanocrystalline diamond film growth. It was found that the SF6/O2 plasma texturing provided a very wide process window where normalized roughness values in the range of 2~16 could be obtained. Significantly improved nucleation densities of ~6.5 × 1010 cm−2compared to conventional mechanical abrasion were achieved after seeding for the textured Si substrate.
  • 6.

    Characteristics of film-type crystal growth mechanism of CO2 hydrate

    Hyun Joo Lee | 김수민 | 이주동 and 1other persons | 2013, 23(2) | pp.93~100 | number of Cited : 0
    Abstract PDF
    Many researches have been carried out to reduce and/or to capture the major global warming gases. Especially,the hydrate formation mechanisms were intensively investigated for carbon dioxide sequestration and storage process applications. In this study, the characteristics of film-type crystal growth mechanism of carbon dioxide hydrate were comprehensively examined. Carbon dioxide hydrate crystal was formed in semi-batch type stir reactor at various pressure conditions while the temperature was fixed to be constant to reduce and minimize the guest gas solubility effects. A supply gas composition was 99.999 % of Carbon dioxide, the observation data was collected by optical microscope adopted CCD camera (Nikon DS-5M/Fi1/2M-U2). This study revealed that the guest gas pressure changes significantly altered the crystal growth mechanism and film growth rate of carbon dioxide hydrate crystal. The critical pressure of the carbon dioxide hydrate of crystal growth mechanism change was found to be 2.0 MPa. The capillary force and gas concentration gradient also significantly changed the film-type crystal growth mechanism of carbon dioxide hydrate crystal.
  • 7.

    Synthesis of nano Cerium(IV) oxide from recycled Ce precusor

    강태희 | Sang Man Koo | 정충호 and 2other persons | 2013, 23(2) | pp.101~107 | number of Cited : 1
    Abstract PDF
    Cerium compounds such as Cerium hydroxide (Ce(OH)3), Cerium chloride (CeCl3 · nH2O), Cerium carbonate hydrate (Ce2(CO3)3 · 8H2O), Cerium oxide (CeO2) were synthesized using recycled Ce precursor. Cerium(IV) oxide of nanoparticles were obtained by Ultra-sonication. Cerium-sodium- sulfate compound was synthesized through acid-leaching and addition of sodium sulfate from 99 wt% purity of Ce precursor as a starting material that was recycled from the waste polishing slurry. Moreover Cerium hydroxide was obtained from Cerium-sodium-sulfate compound by adding to sodium hydroxide solution. Then Cerium chloride was synthesized by adding of hydrochloric acid to Cerium hydroxide. Needleshaped Cerium carbonate hydrate was synthesized in the continuous process and Cerium(IV) oxide with 30~40 nm size was subsequently obtained by the calcinations and dispersion.
  • 8.

    Preparation of nanoparticles CuInSe2 absorber layer by a non-vacuum process of low cost cryogenic milling

    김기현 | Park,Byung-Ok | 2013, 23(2) | pp.108~113 | number of Cited : 0
    Abstract PDF
    Chalcopyrite material CuInSe2 (CIS) is known to be a very prominent absorber layer for high efficiency thin film solar cells. Current interest in the photovoltaic industry is to identify and develop more suitable materials and processes for the fabrication of efficient and cost-effective solar cells. Various processes have been being tried for making a low cost CIS absorber layer, this study obtained the CIS nanoparticles using commercial powder of 6 mm pieces for low cost CIS absorber layer by high frequency ball milling and cryogenic milling. And the CIS absorber layer was prepared by paste coating using milled-CIS nanoparticles in glove box under inert atmosphere. The chalcopyrite CuInSe2 thin films were successfully made after selenization at the substrate temperature of 550oC in 30 min, CIS solar cell of Al/ZnO/CdS/CIS/Mo structure prepared under various deposition process such as evaporation, sputtering and chemical vapor deposition respectively. Finally, we achieved CIS nanoparticles solar cell of electric efficient 1.74 % of Voc 29 mV, Jsc 35 mA/cm2 FF 17.2 %. The CIS nanoparticles-based absorber layers were characterized by using EDS, XRD and HRSEM.
  • 9.

    Concentration and separation of nickel from copper alloy dross using chelating regin

    Lee, Jung-il | kong man sik | Ryu, Jeong-ho | 2013, 23(2) | pp.114~118 | number of Cited : 3
    Abstract PDF
    Separation/recovery of valuable metals such as nickel or tin from copper based alloys has recently attracted from the viewpoints of environmental protection and resource recycling. In this report, preliminary study on concentration and separation of nickel from copper based alloy dross using selective adsorption by chelate resin was performed. The chelate resin used in this study has absorbed copper ions more easily than nickel ions in the metal solution, which could allow the concentration/separation of the nickel from the copper base alloy solution. The final molar ratios of Ni and Cu ions in the two concentrated solutions were 70 and 99 % respectively after three-time flowing the solution through the chelate resin column.