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Thermal Cycling 열처리가 AISI 4330 강의 현미경조직과 기계적 성질에 미치는 효과에 대한 연구
김태일,천성순 대한금속재료학회(대한금속학회) 1981 대한금속·재료학회지 Vol.19 No.3
Thermal Cycling treatments have been applied to AISI 4330 steel for improving the strength and impact toughness. The constant and alternate cycling have been applied. Experimental results showed that a remarkable grain refinement can be obtained by thermal cycling treatments. The strength and impact value were increased by constant cycling, but the strength tended to decrease with increasing the impact value in alternate cycling. It was found that the best thermal cycling condition was the fourth cycle of constant cycling, and the grain size was reduced from about 15∼20㎛ mean grain diameter to 2∼3㎛, by this treatment. The grain refinement can be attributed to the low austenitizing temperature and short soaking time due to the rapid heating rate and the accumulation of residual stress during repeated thermal cycling. It is believed that the increase in strength is caused by the grain refinement and fine carbide precipitation, and increase in impact value is mainly due to the reduction of plate martensite which deteriorates the toughness.
Periodontal regeneration capacity of equine particulate bone in canine alveolar bone defects
김태일,정종평,허민석,박윤정,이상훈 대한치주과학회 2010 Journal of Periodontal & Implant Science Vol.40 No.5
Purpose: This study was performed to evaluate the periodontal wound healing effect of particulate equine bone mineral on canine alveolar bone defects. Methods: Twelve adult male beagle dogs were used as study subjects. The mandibular second and fourth premolars were extracted prior to the experimental surgery, and the extraction sites were allowed to heal for 8 weeks. After periodontal probing,two-walled defects were created at the mesial and distal sides of the mandibular third premolars bilaterally, and the defects were filled with equine particulate bone with collagen membrane or bovine particulate bone with collagen membrane, or collagen membrane alone. The defects without any treatment served as negative controls. After probing depth measurement, animals were sacrificed at 10, 16, and 24 post-surgery weeks for micro-computed tomographic and histomorphometric analysis. Results: The equine particulate bone-inserted group showed significantly decreased values of probing depth and first bone contact compared to the negative control and collagen membrane alone groups at weeks 10, 16, and 24 (P < 0.05). There were no significant differences in the new cementum length, newly-formed bone area, or newly-formed bone volume between equine particulate bone- and bovine particulate bone-inserted groups, both of which showed significantly increased values compared to the negative control and collagen membrane alone groups (P < 0.05). Conclusions: Equine particulate bone showed significant differences in probing depth, first bone contact, new cementum length, newly formed bone area, and bone volume fraction values when compared to the negative control and collagen membrane alone groups. There were no significant differences between equine and bovine particulate bone substitutes in these parameters;therefore, we can conclude that equine particulate bone is equivalent to bovine bone for periodontal regeneration.