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H<sub>2</sub>O<sub>2</sub>/HCl 처리한 Ti 임플란트의 생체활성 평가
유재선,권오성,이오연,이민호,송기홍,Yue J. S.,Kwon O. S.,Lee O. Y.,Lee M. H.,Song K. H. 한국재료학회 2005 한국재료학회지 Vol.15 No.5
Surface treatment play an important role in nucleating calcium phosphate deposition on surgical Ti implant. Therefore, the purpose of this study is to examine whether the precipitation of apatite on cp-Ti and Ti alloys are affected by surface modification in HCl and $H_2O_2$ solution. Specimens were then chemically treated with a solution containing 0.1 M HCl and 8.8M $H_2O_2$ at $80^{\circ}C$ for 30 mins, and subsequently heat-treated at $400^{\circ}C$ for 1 hour. All specimens were immersed in the HBSS with pH 7.4 at $36.5^{\circ}C$ for 15 days, and the surface was examined with XRD, SEM, EDX ana XPS. Also, pure Ti, Ti-6Al-4V and Ti-6Al-7Nb alloy specimens with and without surface treatment were implanted in the abdominal connective tissue of mice for 4 weeks. All specimens chemically treated with HCl and $H_2O_2$ solution have the ability to form a apatite layer in the HBSS which has inorganic ion composition similar to human blood plasma. The average thickness of the fibrous capsule surrounding the specimens implanted in the connective tissue was $38.57\;{\mu}m,\;62.27\;{\mu}m\;and\;45.64\;{\mu}m$ in the cp-Ti, Ti-6Al-4V ana Ti-6Al-7Nb alloy specimens with the chemical treatment respectively, and $52.20\;{\mu}m,\;75.62\;{\mu}m\;and\;66.56\;{\mu}m$ in the commercial specimens of cp-Ti, Ti-6Al-4V and Ti-6Al-7Nb without any treatment respectively. The results of this evaluation indicate that the chemically treated cp-Ti, Ti-6Al-4V ana Ti-6Al-7Nb alloys have better bioactivity and biocompatibility compared to the other metals tested.
열수처리에 의해 석출된 HA 결정이 Ti-6Al-7Nb 합금의 생체활성에 미치는 영향
권오성,최석규,문장원,이민호,배태성,이오연,Kwon O. S.,Choi S. K.,Moon J. W.,Lee M. H.,Bae T. S.,Lee O. Y. 한국재료학회 2004 한국재료학회지 Vol.14 No.9
This study was to investigate the surface properties of electrochemically oxidized Ti-6Al-7Nb alloy by anodic spark discharge technique. Anodizing was performed at current density 30 $mA/cm^2$ up to 300 V in electrolyte solutions containing $DL-{\alpha}$-glycerophosphate disodium salt hydrate($DL-{\alpha}$-GP) and calcium acetate (CA). Hydrothermal treatment was done at $300^{\circ}C$ for 2 hrs to produce a thin outermost layer of hydroxyapatite (HA). The bioactivity was evaluated from HA formation on the surfaces in a Hanks' solution with pH 7.4 at $36.5^{\circ}C$ for 30 days. The size of micropores and the thickness of oxide film increased and complicated multilayer by increasing the spark forming voltage. Needle-like HA crystals were observed on anodic oxide film after the hydrothermal treatment at $300^{\circ}C$ for 2 hrs. When increasing $DL-{\alpha}$-GP in electrolyte composition, the precipitated HA crystals showed the shape of thick and shorter rod. However, when increasing CA, the more fine needle shape HA crystals were appeared. The bioactivity in Hanks' solution was accelerated when the oxide films composed with strong anatase peak with presence of rutile peak. The increase of amount of Ca and P was observed in groups having bioactivity in Hanks' solution. The Ca/P ratio of the precipitated HA layer was equivalent to that of HA crystal and it was closer to 1.67 as increasing the immersion time in Hanks' solution.
열수처리 시간에 따른 Ti-6Al-7Nh 합금의 생체활성 평가
권오성,최석규,박광범,이민호,배태성,이오연,Kwon O. S.,Choi S. K.,Park K. B.,Lee M. H.,Bae T. S.,Lee O. Y. 한국재료학회 2004 한국재료학회지 Vol.14 No.12
This study was to investigate whether the bioactivity of the anodized and hydrothermally treated Ti-6Al-7Nb alloy were affected by the time of hydrothermal treatment. Anodizing was performed at current density 30 $mA/cm^2$ up to 300 V in electrolyte solutions containing $DL-{\alpha}-glycerophosphate$ disodium salt hydrate $(DL-{\alpha}-GP)$ and calcium acetate (CA). Hydrothermal treatment was done at $300^{\circ}C$ for 30 min, 1 hr, 2 hrs, and 4 hrs to produce a thin film layer of hydroxyapatite (HA). The bioactivity was evaluated from HA formation on the surfaces in a Hanks' solution with pH 7.4 at $36.5^{\circ}C$ for 10, 20, and 30 days. Anodic oxide films were porous with pore size of $1\sim4{\mu}m\;and\;3\sim4{\mu}m$ thickness. The anodic oxide films composed with strong anatase peak with presence of rutile peak, and showed the increase in intensity of anatase peak after hydrothermal treatment. It was shown that the intensity of anatase peak increased with increasing the time of hydrothermal treatment but was no difference in rutile peak. The corrosion voltage was the highest in the group of hydrothermal treatment for 2 hrs (Ecorr: -338.6 mV). The bioactivity in Hank's solution was accelerated with increasing the time of hydrothermal treatment.
주메모리 실시간 저장시스템을 위한 개방적 트랜잭션 스케쥴러 라이브러리의 설계 및 구현
권오성(O. S. Kwon),송세혁(S. H. Song),차상균(S. K. Cha),채미옥(M. O. Chae) 한국정보과학회 1996 한국정보과학회 학술발표논문집 Vol.23 No.1A
실시간 데이타베이스 연산들의 정확성은 수행되는 논리적 연산뿐만 아니라 실시간 트랜잭션들의 결과가 도축되는 시간에도 좌우된다. 실시간 DBMS가 가능한 많은 트랜잭션들을 그들의 시간 제약 조건들을 위배하지 않고서 완수하는 것을 보장하기 위해서는 실시간 DBMS의 스케쥴링 전략은 실시간 트랜잭션들과 데이타베이스와 관련된 시간 제약 조건들에 관한 정보들을 이용해야만한다. 이 논문은 M²RTSS(Main-Memory Real-Time Storage System)의 트랜잭션들에 대한 몇 가지의 스케쥴링 알고리듬을 제안한다. 이러한 알고리듬들을 구현한 스케쥴러들은 시스템의 재사용성과 확장가능성을 향상시키기 위해 객체지향 방식에 의해 설계되었다. M²RTSS를 이용하는 프로그래머는 어떤 스케쥴링 알고리듬도 선택할 수 있을 뿐만 아니라 시스템의 다른 부분에 영향을 끼치지 않고서 자신의 응용 분야에 적절한 새로운 알고리듬을 구현할 수 도 있다. 우리는 이 연구가 진행됨에 따라 M²RTSS가 다양한 응용 분야를 지원하는 일반적인 실시간 DBMS로 발전되기를 희망한다.
김방룡,권오성,조경환,Kim, R.R.,Kwon, O.S.,Cho, K.H. 한국전자통신연구원 1998 전자통신동향분석 Vol.13 No.3
우리나라의 통신시장은 세계 10위권 내에 들 정도로 거대한 규모이지만, 통신사업자의 국제경쟁력이 아직은 미약할 뿐아니라, 최근 국내경제 악화로 기업가치가 급격히 평가절하되어 있어서 통신시장이 개방되면 미국을 비롯한 통신선진국들의 목표시장이 될 가능성이 매우 높다. 이하에서는 주요 외국 통신사업자들의 해외진출에 관한 세계적 동향을 간략히 살펴보고, 우리나라 통신시장에 진출한 외국사업자의 현황 및 전망을 고찰함으로써 향후 본격적인 대외개방에 대비한 전략적 시사점을 모색하고자 한다.