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가압 소결법으로 합성된 Ti3SiC2 소결체의 기계적 특성
조경선,황성식,권혁보,박상환 한국세라믹학회 2010 한국세라믹학회지 Vol.47 No.6
Nano laminated bulk Ti3SiC2 was synthesized by hot press process using TiCx/Si powder mixture at the temperature range of 1300oC~1500oC. pure Ti3SiC2 was synthesized by a hot pressing above 1400oC, while unreacted TiCx were remained in bulk Ti3SiC2 which synthesized below 1400oC. The sintering density of bulk Ti3SiC2 were varied with the amount of TiCx. It was found that the mechanical properties and micro structures of bulk Ti3SiC2 were closely related to the amounts of TiCx which was controlled by the hot pressing temperature. The TiCx increase the flexural strength of bulk Ti3SiC2, while the fracture toughness and thermal shock resistance of bulk Ti3SiC2 were decreased with the content of TiCx. The plastic deformations of bulk Ti3SiC2 were appeared above 1000oC.
구역분할 디스크를 사용하는 멀티미디어 서버에서 새로운 세션 시작에 따른 스케줄링 지연 현상의 최소화
조경선,원유집,고건,신일훈 한국정보과학회 2004 정보과학회논문지 : 시스템 및 이론 Vol.32 No.7
Zoning technology of disk improved the performance of disk subsystem with increase of storage capacity and average transfer bandwidth. SCAN disk scheduling with double buffering is used to utilize the performance of zoned disk in multimedia system. However, this method has a problem that generates jitter when the number of steams increases. In this article, we propose the novel approach, pre-buffering policy, to overcome this problem. Pre-buffering avoids jitter by buffering the lack of data before starting service, which is estimated from the current cycle length and the maximum cycle length. We can calculate cycle length, data size needed in each cycle and the possible lack of data caused by the increase of the number of streams using the numerical model of disk subsystem. Pre-buffering can be applied for multimedia systems and contribute to provide clients with high quality service without jitter. 디스크의 구역분할기술(zoning technology)은 디스크의 저장용량과 평균 전송 대역폭을 증가시킴으로써, 디스크 서브시스템의 성능을 향상시켰다. 멀티미디어 시스템에서 구역분할 디스크의 성능을 충분히 이용하기 위하여 이중 버퍼링을 하는 SCAN 스케줄링을 사용한다. 하지만, 이 방식은 새로운 스트림의 요청 시에 지터(jitter)를 발생시키는 문제점이 있다. 본 논문에서는 이 문제를 해결하기 위한 선행 버퍼링(pre-buffering) 기법을 제안한다. 선행 버퍼링은 디스크 서브시스템의 수학적 모델을 통하여 스트림의 개수에 따른 주기시간과 각 주기시간에 필요한 데이타 양, 그리고 새로운 스트림 요청 시에 발생하는 데이타의 부족분을 예측하고, 예상되는 데이타의 부족분을 각 스트림의 서비스 전에 미리 버퍼링함으로써, 지터를 방지한다. 선행 버퍼링 기법은 멀티미디어 서버에 적용되어 사용자에게 지터 없는 고품질의 서비스를 제공하는 데 기여할 수 있다.
조경선 한국지식재산학회 2004 産業財産權 Vol.- No.16
Present valuation system of technology including industrial property rights such as patents and utility models has been activated to effectively perform government supports on projects in both research and developments stages and commercialization stages. Also, it is expected that the technology effectiveness is being reconsidered through technology appraisal activities with more focus on its application such as technology transfer, technology commercialization and technology guarantee offer. However, those who currently secure legal status as industrial property right appraisers are the ones who obtain their status in the law concerned with evaluation of real estates, even though evaluation of industrial property rights is quite different from that of real estates. In this study, we examined not only the laws related with the technology valuation but suggested solutions for proper operation of the valuation system. Therefore, the purpose of this study is to show the direction of technology valuation system in the future to activate technology commercialization by securing the stable legal foundation and building necessary infrastructures.
가압 소결법으로 합성된 Ti<sub>3</sub>SiC<sub>2</sub> 소결체의 기계적 특성
조경선,황성식,권혁보,박상환,Cho, Gyoung-Sun,Hwang, Sung-Sic,Kwon, Huck-Bo,Park, Sang-Whan 한국세라믹학회 2010 한국세라믹학회지 Vol.47 No.6
Nano laminated bulk $Ti_3SiC_2$ was synthesized by hot press process using TiCx/Si powder mixture at the temperature range of $1300^{\circ}C\sim1500^{\circ}C$. pure $Ti_3SiC_2$ was synthesized by a hot pressing above $1400^{\circ}C$, while unreacted TiCx were remained in bulk $Ti_3SiC_2$ which synthesized below $1400^{\circ}C$. The sintering density of bulk $Ti_3SiC_2$ were varied with the amount of TiCx. It was found that the mechanical properties and micro structures of bulk $Ti_3SiC_2$ were closely related to the amounts of TiCx which was controlled by the hot pressing temperature. The TiCx increase the flexural strength of bulk $Ti_3SiC_2$, while the fracture toughness and thermal shock resistance of bulk $Ti_3SiC_2$ were decreased with the content of TiCx. The plastic deformations of bulk $Ti_3SiC_2$ were appeared above $1000^{\circ}C$.
다층 기공구조를 갖는 다공성 반응소결 탄화규소 다공체 제조
조경선,김규미,박상환,Cho, Gyoung-Sun,Kim, Gyu-Mi,Park, Sang-Whan 한국세라믹학회 2009 한국세라믹학회지 Vol.46 No.5
Reaction Bonded Silicon Carbide(RBSC) has been used for engineering ceramics due to low-temperature fabrication and near-net shape products with excellent structural properties such as thermal shock resistance, corrosion resistance and mechanical strength. Recently, attempts have been made to develop hot gas filter with gradient pore structure by RBSC to overcome weakness of commercial clay-bonded SiC filter such as low fracture toughness and low reliability. In this study a fabrication process of porous RBSC with multi-layer pore structure with gradient pore size was developed. The support layer of the RBSC with multi-layer pore structure was fabricated by conventional Si infiltration process. The intermediate and filter layers consisted of phenolic resin and fine SiC powder were prepared by dip-coating of the support RBSC in slurry of SiC and phenol resin. The temperature of $1550^{\circ}C$ to make Si left in RBSC support layer infiltrate into dip-coated layer to produce SiC by reacting with pyro-carbon from phenol resin.