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이기주,Dongxu Tang,K. Park,조원승 대한금속·재료학회 2010 METALS AND MATERIALS International Vol.16 No.1
Porous Y-doped (Ba,Sr)TiO3 ceramics were prepared by the spark plasma sintering of (Ba,Sr)TiO3 powders with different amounts of carbon black, and by subsequently burning out the carbon black acting as a pore precursor. The microstructure, PTCR and gas-sensing characteristics for porous Y-doped (Ba,Sr)TiO3 ceramics were investigated. Spark plasma sintered (Ba,Sr)TiO3 ceramics revealed a very fine microstructure containing submicron-sized grains with a cubic phase and revealed an increased porosity after the carbon black was burned out. As a result of reoxidation treatment, the grain size of the (Ba,Sr)TiO3 ceramics increased to a few μm and the cubic phase transformed into a tetragonal phase. The phase transformation of (Ba,Sr)TiO3ceramics was affected by grain size. The PTCR jump in the (Ba,Sr)TiO3 ceramics prepared by adding 40vol.% carbon black showed an excellent value of 4.72 × 106, which was ten times higher than the PTCR jump in (Ba,Sr)TiO3 ceramics. The electrical resistivity of the porous (Ba,Sr)TiO3 ceramics was recovered as the atmosphere changed from a reducing gas (N2) to an oxidizing gas (O2) under consecutive heating and cooling cycles.
카본블랙을 첨가하여 제조한 다공성 BaTiO<sub>3</sub>계 세라믹스의 미세구조 및 PTCR 특성 변화
이기주,당동욱,조원승,Lee, Ki-Ju,Tang, Dongxu,Cho, Won-Seung 한국분말야금학회 2011 한국분말재료학회지 (KPMI) Vol.18 No.1
As a pore precursor, carbon black with different content of 0 to 60 vol% were added to (Ba,Sr)$TiO_3$ powder. Porous (Ba,Sr)$TiO_3$ ceramics were prepared by pressureless sintering at $1350^{\circ}C$ for 1h under air. Effects of carbon black content on the microstructure and PTCR characteristics of porous (Ba,Sr)$TiO_3$ ceramics were investigated. The porosity of porous (Ba,Sr)$TiO_3$ ceramics increased from 6.97% to 18.22% and the grain size slightly decreased from $7.51\;{\mu}m$ to $5.96\;{\mu}m$ with increasing carbon black contents. PTCR jump of the (Ba,Sr)$TiO_3$ ceramics prepared by adding carbon black was more than $10^5$, and slightly increased with increasing carbon black. The PTCR jump in the (Ba,Sr)$TiO_3$ ceramics prepared by adding 40 vol% carbon black showed an excellent value of $9.68{\times}10^5$, which was above two times higher than that in (Ba,Sr)$TiO_3$ ceramics. These results correspond with Heywang model for the explanation of PTCR effect in (Ba,Sr)$TiO_3$ ceramics. It was considered that carbon black is an effective additive for preparing porous $BaTiO_3$ based ceramics. It is believed that newly prepared (Ba,Sr)$TiO_3$ cermics can be used for PTC thermistor.
발사체 시스템 설계단계의 형상 및 구조 설계/분석 프로세스
이기주,조상범,노웅래,선병찬 한국항공우주학회 2015 한국항공우주학회 학술발표회 논문집 Vol.2015 No.11
본 논문에서는, 액체로켓 엔진이 사용되는 소모성 다단형 발사체 시스템을 설계하는 단계에서 고려해야 하는 사항들과 절차를 시스템 차원의 하중과 강도 관점에서 고찰한다. 먼저 추진제 중량 버짓을 설정해서 추진제 탱크의 크기와 발사체의 전체적인 형상을 결정한다. 이어서, 가벼우면서도 신뢰성이 높은 구조 설계를 도출하기 위해서, 구성품 형상 설계, 중량 분석, 하중 해석, 모드 분석, 강성과 강도 분석 등의 설계 검토를 수행한다. In this study, a load-and-strength aspect of the system design and analysis process is examined for an expendable multi-stage launch vehicle that employs liquid rocket engines. First, a stipulation of propellant mass budget that satisfies mission requirements at a system level leads to propellant tank sizes and overall configurations. Subsequently, various design studies and analyses associated with component sizing, mass properties, loads, modes, stiffness and strength are conducted to derive a lightweight and reliable launcher design.
이기주 한국러시아문학회 2018 러시아어문학 연구논집 Vol.62 No.-
В «Вечерах» любовная тема - это арена борьбы добра со злом. В том случае, если человеку удаётся подчинить себе нечистую силу и заставить её служить, то победа остаётся за ним. Если же человек оказывается под властью нечистой силы, то ему суждено погибнуть. Так у Гоголя проявляется инфернальная сущность самых, казалось бы, обыденных явлений: кокетства, наивности и инфантильности, жадности, сластолюбия. Все они так или иначе связаны с кознями нечистой силы, и даже любовь не всегда может преодолеть их, как это происходит в «Страшной мести» или в «Вечере накануне Ивана Купала». Любовь оказывается всепобеждающей только при условии выполнения героями ещё некоторых требований к ним.