Anchorage plays an important role in orthodontic treatment. Recently, some clinicians have tried to use skeletal anchorage system(titanium miniscrews and microscrews) in treatment due to their many advantages such as ease of insertion and removal, low cost, immediate loading, and the ability to place miniscrews in any area of alveolar bone. The purpose of this study was to investigate the histopathologic change of alveolar bone density around miniscrew under variable ortho -donticforceinyoung-adultdogs, throughthepolarizingmicroscopic findings. For this study, three young adult mongrel dogs(6-months in age) were used, 12 titanium miniscrews were inserted into the palatal bone(4 miniscrews placed in each dog), and then miniscrews were loadedwithorthodonticforce [50gm(F1),100gm(F2),250gm(F3), 500gm(F4)] immediately after implantation. After 1, 3 and 6 weeks, the animals were sacrificed. Then the miniscrews and surrounding bone of dogs were removed, respectively. The grinding samples along the long axis of miniscrew were made. The changes of bone density and thrombosis were examined under the polarizing microscope. Bone density was determined as color changes. The results of this study were as follows. 1. There was no thrombosis in the F1 group. But thrombosis was seen in 1 week of T side, 1, 3, 6 weeks of P side in the F2 group, 1, 3 weeks of T side, 1, 3, 6 weeks of P side in the F3 group and 1, 3, 6 weeks of both P and T side in the F4 group. 2. The changes of bone density decreased in P side more than T side in 1 week, while more decreased P side in 3 weeks than 1 week. In 6 weeks, bone density more increased in T side than P side along the middle & apex. 3. As orthodontic force increased, there was severe thrombosis, especially in cervical of P side. As it went up to 3, 6 weeks, thrombosis was decreased but remained. 4. As orthodontic force increased, bone density more severely decreased due to bone destruction in 1 and 3 weeks, but more slowly increased due to bone formation in 6 weeks. Based on the results of this study, in the practice, because of optimal orthodontic force for the most of tooth movement was less than 150gm, I thought that miniscrews could play role of use of skeletal anchorage immediately after implantation. In the more than 250gm & 500gm of orthodontic force, I thought that miniscrews would be delayed as use of skeletal anchorage after loss of bone was restored.

유성밀로써 사문석과 활석을 분쇄시 X-ray 회절분석, FT-IR, DSC-TG, 입도분석 그리고 SEM관찰 등을 이용하여 결정조직과 물리적 특성변화를 조사하였다. 분쇄기간이 증가함에 따라 사문석과 활석 원시료의 결정피크가 점처 감소하여 120분 이상 분쇄시 비정질상으로 변하였으며 이와 같은 변화는 마그네슘 결정 조직의 무질서에 기인한다. 분쇄된 시료에서 나타나는 흡열반응의 피크는 원시료보다 낮은 온도에서 관찰되었다. 또한 불규칙한 모양의 원시료는 분쇄처리를 실시함에 따라 구형의 응집체로 변하였다.

현재 제철소에서 소결공정에서 탈황공정 중 발생되는 제철 탈황분진은 현재 연간 100,000톤 이상으로 추정하고 있으나 80%이상이 재활용되지 못하고 있다. 발전소에서 발생되는 탈황석고는 사업장폐기물로 분류되어 석고보드 등으로 재활용되고 있으나, 제철탈황분진은 중금속 등의 유해성분으로 인하여 지정폐기물로 분류되어 재활용되지 못하고 인근 매립장에서 처리되고 있다. 본 연구는 탈황분진의 안정화를 위하여 지르코늄 유성밀을 사용한 분쇄방법으로 처리한 후 그 특성을 분석하였다. 유성밀로 분쇄후 분석한 결과 입자의 크기는 2.8 ㎛에서 0.5 ㎛의 크기로 작아졌으며, XRF, TGA 분석은 분쇄전과 거의 동일하였다. XRD분석에서는 피크의 강도가 더 작아진 것으로 유해성이 감소된 것으로 판단되며, 폐기물공정시험방법으로 분석한 중금속의 농도는 Cu의 경우 1/6이상 감소하였다.