• Clinical and Experimental Pediatrics
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• 제49권5호
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• pp.565-569
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• 2006

Rothmund-Thomson 증후군은 상염색체 열성질환으로 다형피부증(poikiloderma), 희박한 모발과 눈썹, 저신장, 골격계 이상, 유소년기 백내장과 악성종양의 위험이 높은 것으로 특징지어지는 증후군이다. 골격계의 이상은 RTS 환아의 68%에서 보고되었고 신체전반의 골격계 이형성으로 형성부전이나 기형으로 나타난다. 요골형성부전, 엄지손가락 저형성, 골감소증, 슬개골 저형성이나 슬개골 형성 부전 등이 보고되어 있다. 흔치 않은 증상으로는 말안장코와 삼각형의 얼굴 등이 보고되어있다. RTS에서 골육종을 포함한 악성종양의 발생빈도가 높고 면역학적 이상이 보고되어 있다. 피부종양이 가장 흔하며 상피세포암, 기저세포암, Bowen's disease 등이 있고 두 번째로는 육종이 흔하다. 저자들은 전신적으로 혈관확장 및 과색소침착을 보이는 다형 피부 소견과 함께 요골형성부전, 척골기형, 엄지손가락형성부전, 슬개골 형성부전의 골격계 기형이 있으면서 이후 좌측 경골에 골육종이 발생한 Rothmund-Thomson 증후군을 경험하였기에 보고하는 바이다.

• Journal of Mechanical Science and Technology
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• 제20권6호
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• pp.738-747
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• 2006

The friction behaviour of Si-wafer, diamond-like carbon (DLC) and two self-assembled monolayers (SAMs) namely dimethyldichlorosilane (DMDC) and diphenyl-dichlorosilane (DPDC) coated on Si-wafer was studied under loading conditions in milli-newton (mN) range. Experiments were performed using a ball-on-flat type reciprocating micro-tribo tester. Glass balls with various radii 0.25 mm, 0.5 mm and 1 mm were used. The applied normal load was in the range of 1.5 mN to 4.8 mN. Results showed that the friction increased with the applied normal load in the case of all the test materials. It was also observed that friction was affected by the ball size. Friction increased with the increase in the ball size in the case of Si-wafer. The SAMs also showed a similar trend, but had lower values of friction than those of Si-wafer In-terestingly, for DLC it was observed that friction decreased with the increase in the ball size. This distinct difference in the behavior of friction in DLC was attributed to the difference in the operating mechanism. It was observed that Si-wafer and DLC exhibited wear, whereas wear was absent in the SAMs. Observations showed that solid-solid adhesion was dominant in Si-wafer, while plowing in DLC. The wear in these two materials significantly Influenced their friction. In the case of SAMs their friction behaviour was largely influenced by the nature of their molecular chains.