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2008, Vol.18, No.2

  • 1.

    Structural characteristics of non-nucleus Abalone half pearl cultured by a new technique

    김혜연 | Kwang Bo Shim | Jong-Wan Park and 1other persons | 2008, 18(2) | pp.57~61 | number of Cited : 1
    Abstract PDF
    Non-nucleus Abalone half pearls were cultured by a new technique and their structural characteristics were analyzed using an electron microscopy. This technique was found to grow the pearls depending on the shape of the internal organ of an abalone because this technique induces the pearl layers without adding any nucleus on the specified damage region of a shell. The obtained pearls exhibit natural shapes with a specific luster. The SEM analysis shows that the pearl layers are about 0.34 μm with an uniform thickness and the surface of the shell is characterized by the pyramidshaped bulge with a regular arrangement, which is a typical feature of single-shell. These characteristics of the pearls are thought to develop in the highly-valued Korean gems.
  • 2.

    The synthesis and crystal structure of [(η5-Cp)Co]2(1,2-S,S-o-carborane)(C12H20B10S2Co2)

    CHO SUNG IL | 2008, 18(2) | pp.62~67 | number of Cited : 0
    Abstract PDF
    An Organometallic compound, C12H20B10S2Co2, was synthesized from o-carborane, Cp*Co(S2C2B10H10) and BH3·THF. The molecular structure of this complex has been determined by X-ray diffraction. Crystallographic data: monoclinic, space group Cc, a = 15.981(4) Å, b = 15.478(17) Å, c = 12.0562(17) Å, β = 115.063(16)o, Z = 4, V = 9683(4) Å3. The structure was solved by direct methods and refined by full-matrix leat-squares methods to give a model with a reliability factor R = 0.0630 for 9948 reflections.
  • 3.

    Growth of AlN crystals by the sublimation process

    Kang, Seung-Min | 2008, 18(2) | pp.68~71 | number of Cited : 14
    Abstract PDF
    AlN crystals were grown by the sublimation process. As grown AlN crystals were the polycrystalline boule in the form of the agglomerate of small AlN single crystalline AlN. As-grown AlN boule has a length about 2~3 mm long and a diameter of 1 inch. The carbon impurities were observed on the surface and inside of the grown AlN crystals and the growth behavior was investigated by optical microscopy and SEM observation.
  • 4.

    Effect of heat-treatment on the structural and electrical properties of ZnO thin films by the sol-gel method

    이승엽 | Park,Byung-Ok | 2008, 18(2) | pp.72~75 | number of Cited : 0
    Abstract PDF
    Zinc oxide (ZnO) thin films were prepared by a sol-gel method. The structural and electrical properties were investigated by varying drying and annealing temperatures. The thin films were coated (250 nm) by spin-coating method on glass substrates. The optimum drying temperature of ZnO thin films was 300℃ where the resistivity was the lowest and the preferred c-axis orientation was the highest. The annealing was carried out in air and inert atmospheric conditions. The degree of the preferred c-axis orientation was estimated. The highest preferred c-axis orientation was recorded at 600℃. The preferred c-axis orientation and grain growth resulted in the mobility enhancement of the ZnO thin films, and the lowest resistivity was 0.62 Ω·cm at 600℃.
  • 5.

    Characterization of transparent ATO conducting films prepared by RF magnetron sputtering

    Sungwook Lee | HONG, BYUNGYOU | Yong Seob Park | 2008, 18(2) | pp.76~80 | number of Cited : 1
    Abstract PDF
    In this study, we synthesized ATO films using RF magnetron sputtering method consisted of SnO₂target added Sb of 6 wt% and investigated the effect of O₂on structural, electrical, and optical properties of ATO films. As a result, in case of O₂/Ar ratio of 0.11, we obtained ATO films exhibit the properties such as the resistivity about 8 × 10-³ [Ω-cm], the transmittance of 85.17 %, and retile structure.
  • 6.

    Structural characteristics of ZnO nanostructures synthesized by the thermal evaporation method

    방신영 | Bonggeun Choi | Kwang Bo Shim and 2other persons | 2008, 18(2) | pp.81~86 | number of Cited : 1
    Abstract PDF
    ZnO nanowires were synthesized by the thermal evaporation method and their growth mechanisms were confirmed by the characterization of the structural features depending on the growth conditions. The increase of vaporization temperature accelerates the growth rate and morphologies of ZnO nanowires were drastically changed at the temperature over 1000℃, because of changed CO/CO₂ partial pressure. Au particles play their role on growth of ZnO nanowire as catalyst at growth temperature over 700℃. The synthesized ZnO nanowires exhibit blue emission at 380 nm.
  • 7.

    Effects of process temperature on the microstructure and magnetic properties of electrodeposited Co-Pt alloy thin films

    이창형 | SUH, SUJEONG | 정근희 and 2other persons | 2008, 18(2) | pp.87~90 | number of Cited : 0
    Abstract PDF
    Co-Pt alloy thin films were galvanostatically electrodeposited on Ru (30 nm)/Ta (5 nm)/Si (100) substrates from a amino-citrate based electrolyte. We used Ru(0002)-oriented buffer layers to control the crystallinity and orientation of the Co-Pt alloy thin films. The effect of solution temperature on the microstructure and magnetic properties of the Co-Pt alloy thin film was investigated. The samples were characterized by EDS, FESEM, XRD diffractometer using Cu Kα radiation. The magnetic properties of these films were analyzed by a VSM and torque magnetometer. The Co-Pt alloy thin films were exhibited very high out-of-plane coercivity and squareness of the multilayer were 6527 Oe and 0.93, respectively, without heat treatment.
  • 8.

    Efficiency of catalyst-coated ceramic filter with acid treatment

    조을훈 | Kwang Suck Suh | 김수효 and 4other persons | 2008, 18(2) | pp.91~95 | number of Cited : 0
    Abstract PDF
    코디어라이트를 원료로 하여 다공성 세라믹 필터를 제조하였고, 진공함침법으로 V2O5 촉매를 코팅하였다. 제조된 세라믹 필터의 기공률은 58 %, 압축강도는 10 MPa, 400℃, 5 cm/sec의 유속에서 압력손실은 1,200 Pa이었다. V2O5 촉매의 경우 NOx에 대해 80 % 이상의 처리효율을 나타내었고, 산처리에 의한 필터의 비표면적 증가를 통해 처리효율을 약10 % 개선할 수 있었다. 이는 필터의 비표면적 증가를 통해 코팅된 촉매의 분산성을 향상시킴으로써 촉매의 활성점이 증대되었기 때문으로 판단된다. drop of 1200 Pa at the face velocity of 5 cm/sec and 400℃. NOx removal efficiency of only V2O5 coated on cordierite filter showed the removal efficiency of 80 %, and it was improved up to 90 % by increasing specific surface area of filter elements from the acid treatment. The high surface area is due to the removal of Mg and Al ions from the silicate structure and subsequent generation of free amorphous silicate on the surface of the cordierite.