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급속 소결에 의한 인공관절용 나노구조 2/3 Cr-ZrO<sub>2</sub> 복합재료 제조 및 특성
강현수,강보람,손인진,Kang, Hyun-Su,Kang, Bo-Ram,Shon, In-Jin 한국재료학회 2014 한국재료학회지 Vol.24 No.9
Despite having many attractive properties, $ZrO_2$ ceramic has a low fracture toughness which limits its wide application. One of the most obvious tactics to improve its mechanical properties has been to add a reinforcing agent to formulate a nanostructured composite material. Nanopowders of $ZrO_2$ and Cr were synthesized from $CrO_3$ and Zr powder by high energy ball milling for 10 h. Dense nanocrystalline $2/3Cr-ZrO_2$ composite was consolidated by a high-frequency induction heated sintering method within 5 min at $600^{\circ}C$ from mechanically synthesized powder. The method was found to enable not only rapid densification but also the inhibition of grain growth, preserving the nano-scale microstructure. Highly dense $2/3Cr-ZrO_2$ composite with relative density of up to 99.5% was produced under simultaneous application of a 1 GPa pressure and the induced current. The hardness and fracture toughness of the composite were 534 kg/mm2 and $7MPa{\cdot}m1/2$, respectively. The composite was determined to have good biocompatibility.
강현수,김미진,신용호,전용철,Hyun Su Kang,Mi-Jin Kim,Yong Ho Shin,Yong Chull Jeun 한국식물병리학회 2023 식물병연구 Vol.29 No.4
당근 세균잎마름병을 일으키는 Xanthomonas hortorum pv. carotae는 당근 생산량에 큰 피해를 주는 병 중 하나로 국내에서 아직 방제에 대한 연구가 미흡한 실정이다. 본 연구에서는 당근 세균잎마름병균에 효과적인 농약을 선발하기 위하여 3종의 항생제 streptomycin, oxolinic acid, kasugamycin, 2종의 구리제 copper hydroxide, copper sulfate basic 그리고 길항근권세균 Burkholderia gladioli MRL408-3, Pseudomonas fluorescens TRH415-2, Bacillus cereus KRY505-3을 선정하여 인공배지를 이용하여 이들의 직접적인 항균효과를 조사하였다. 이 중 항생제 streptomycin, oxolinic acid와 길항미생물 MRL408-3을 처리한 배지에서 억제환이 형성되었다. 당근 잎에 농약과 항균효과를 보였던 길항미생물 MRL408-3을 전처리한 후 당근 세균잎마름병균을 접종하였더니 streptomycin과 oxolinic acid을 전처리한 당근 잎에 높은 방제효과를 보였다. 이들 당근 잎 표면의 장방출주사현미경 이미지에서 streptomycin과 oxolinic acid를 전처리한 잎에서는 세균 수가 무처리한 잎과 비교하여 급격히 감소하였다. 이들 결과를 통해 streptomycin과 oxolinic acid와 같은 항생제가 다른 약제에 비해 방제 효과가 뛰어나다는 것을 알 수 있었다. 본 연구는 당근 세균잎마름병에 대한 이상적인 방제 시스템을 구축하는 데 도움이 되는 자료로서 가치가 있을 것으로 생각된다. Bacterial blight of carrot caused by Xanthomonas hortorum pv. carotae (Xhc) is one of the serious diseases of carrot, of which control measures has not been still established in the domestic farm. In this study, in order to select effective sterilizer for bacterial blight of carrots, three antibiotics such as streptomycin, oxolinic acid, kasugamycin, two copper compounds like copper hydroxide and copper sulfate basic and three rhizobacteria Burkholderia gladioli MRL408-3, Pseudomonas fluorescens TRH415-2 and Bacillus cereus KRY505-3 were selected to investigate their direct antibacterial effects using artificial media, aiming to identify effective pesticides against Xhc. Among them, treated medium with antibiotics such as streptomycin, oxolinic acid, and the antagonistic rhizobacteria MRL408-3 were formed inhibition zone. The agrochemicals and the rhizobacteria MRL408-3, which showed antibacterial effects on carrot leaves, pre-treated on the carrot leaves and then inoculated with Xhc. High control effects were shown on the carrot leaves pre-treated with both streptomycin and oxolinic acid. Scanning electron microscopy images of the carrot leaf surfaces showed that the population of bacteria decreased significantly on leaves pre-treated with streptomycin and oxolinic acid. From these results, it can be inferred that antibiotics like streptomycin and oxolinic acid exhibit superior control effects compared to other agents. This study provides valuable insights towards establishing an effective control system for bacterial blight of carrot.
고주파 유도 가열에 의한 나노구조 Mg<sub>4</sub>Al<sub>2</sub>Ti<sub>9</sub>O<sub>25</sub> 합성 및 소결과 기계적 성질
강현수,도정만,윤진국,손인진,Kang, Hyun-Su,Doh, Jung-Mann,Yoon, Jin-Kook,Shon, In-Jin 한국재료학회 2014 한국재료학회지 Vol.24 No.2
Nanocrystalline materials have received much attention as advanced engineering materials with improved physical and mechanical properties, including high strength, high hardness, excellent ductility and toughness. In this study, nanopowders of $Al_2O_3$, MgO and $TiO_2$ were prepared as starting materials by high energy ball milling for the simultaneous synthesis and sintering of the nanostructured compound $Mg_4Al_2Ti_9O_{25}$ by high-frequency induction heating process. The highly dense nanostructured $Mg_4Al_2Ti_9O_{25}$ compound was produced within one minute by the simultaneous application of 80MPa pressure and induced current. The sintering behavior, grain size and mechanical properties of the $Mg_4Al_2Ti_9O_{25}$ compound were evaluated.
나노구조 MgAl2O4-Mg3Al2Si3O12 복합재료 합성과 동시 소결 및 기계적 성질
강현수 ( Hyun Su Kang ),도정만 ( Jung Mann Doh ),윤진국 ( Jin Kook Yoon ),손인진 ( In Jin Shon ) 대한금속재료학회(구 대한금속학회) 2014 대한금속·재료학회지 Vol.52 No.10
Nanopowders of MgO, Al2O3 and SiO2 were made by high energy ball milling. The simultaneous synthesis and consolidation of nanostuctured MgAl2O4-Mg3Al2Si3O12 composites from milled 4MgO, 2Al2O3 and 3SiO2 powders was investigated by a high-frequency induction heating process. The advantage of this process is that it allows very quick densification to near theoretical density and inhibition of grain growth. Highly dense nanostructured MgAl2O4-Mg3Al2Si3O12 composites were produced with a simultaneous application of 80 MPa pressure and an induced current within 1 min. The relative density and fracture toughness of the composite were 98% and 3.2 MPam1/2, respectively. The fracture toughness of the MgAl2O4-Mg3Al2Si3O12 composite was higher than that of monolithic MgAl2O4.