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SiO<sub>2</sub>와 Al<sub>2</sub>O<sub>3</sub> 첨가가 지르콘의 기계적 특성에 미치는 영향
조범래,Cho, Bum-Rae 한국재료학회 2011 한국재료학회지 Vol.21 No.4
Zircon has excellent thermal, chemical, and mechanical properties, but it is hard to make a dense sintered product because of dissociation during the sintering process. This study analyzes how the addition of $SiO_2$ and $Al_2O_3$ affects the mechanical properties of sintered zircon, particularly in regards to reducing the thermal dissociation and improving the mechanical properties of $ZrSiO_4$. Zircon specimens containing different amounts of $SiO_2$ and $Al_2O_3$ were prepared and sintered to observe how the mechanical properties of $ZrSiO_4$ changed according to the differing amount of $SiO_2$ and $Al_2O_3$. The $ZrSiO_4$ that was used for the starting material was ground by ball mill to an average particle size of 3 ${\mu}m$. The $SiO_2$ and $Al_2O_3$ that was used for additives were ground to an average particle size of 3 ${\mu}m$ and 0.5 ${\mu}m$, respectively. Adding $SiO_2$ resulted in transformation in the liquid phase at high temperatures, which had little effect on suppressing the thermal dissociation but enhanced the mechanical properties of $ZrSiO_4$. When $Al_2O_3$ was added, the mechanical properties of $ZrSiO_4$ decreased due to the formation of pores and abnormal grains in the microstructure of the sintered zircon.
SiO<sub>2</sub>와 3Y-TZP 첨가가 지르콘의 기계적 물성에 미치는 영향
장호수,조범래,Jang, Ho Su,Cho, Bum Rae 한국재료학회 2016 한국재료학회지 Vol.26 No.4
Zircon, having excellent thermal, chemical, and mechanical properties, is utilized in refractory materials, electronic materials, chemical machines, structural materials, etc. However, zircon generally shows thermal dissociation to zirconia($ZrO_2$) and silica($SiO_2$) around the sintering temperature of $1540^{\circ}C$, and when zircon particles are small and impurities are present, thermal dissociation is known to occur at around $1100^{\circ}C$. This reduces the mechanical properties of $ZrSiO_4$. In this research, the effect of adding $SiO_2$ and 3Y-TZP to $ZrSiO_4$ has been studied in order to suppress dissociation and improve the mechanical properties. Addition of $SiO_2$ suppressed the dissociation of $ZrSiO_4$ at lower temperatures. It also enabled optimum packing between the particles, resulting in a dense microstructure and good mechanical properties. When 3Y-TZP was added, recombination with the dissociated $SiO_2$ resulted in good mechanical properties by suppressing the generation of pores and the densification of the microstructure.
3Y-TZP의 기계적 물성에 미치는 영향: (II) 알루미나의 첨가
양성구,배경만,조범래,강종봉,Yang, Seong-Koo,Bae, Kyung-Man,Cho, Bum-Rae,Kang, Jong-Bong 한국세라믹학회 2005 한국세라믹학회지 Vol.42 No.6
Although a lot of studies in fracture toughness of Y-TZP ceramics for structural applications have been done, it remains an important challenge to be able to improve fracture toughness of Y-TZP ceramics. In this research, milling method adding monoclinic zirconia and $Al_2O_3$ to 3Y-TZP was introduced to improve the fracture toughness of 3Y-TZP. Experimental results showed that addition of small amount of $Al_2O_3$ causes to make lots of oxygen vacancies (VO) by substituting $Al^{3+}$ for $Zr^{4+}$. It is believed that the produced vacancies provides useful routes far mass transfer. Y-TZP ceramics having higher microhardness and better fracture toughness was fabricated by sintering at $1400^{\circ}C$.
3Y-TZP의 기계적 물성에 미치는 영향: (I) 단사정지르코니아의 첨가
양성구,배경만,조범래,강종봉,Yang, Seong-Koo,Bae, Kyung-Man,Cho, Bum-Rae,Kang, Jong-Bong 한국세라믹학회 2005 한국세라믹학회지 Vol.42 No.6
Y-TZP(Yttria-stabilized Tetragonal Zirconia Polycrystal) ceramics are of great interest as engineering and structural materials due to their excellent mechanical properties arising from transformation toughening, it is also reported that the 3Y-TZP($3 mol\%$ Yttria-stabilized Tetragonal Zirconia Polycrystal) has the best mechanical properties in Y-TZP ceramics. But to use widely for engineering and structural materials, it remains an important challenge to be able to improve its fracture toughness. In order to produce the 3Y- TZP ceramics showing much better mechanical properties, milling method adding monoclinic zirconia to 3Y-TZP was adopted and the resultant mechanical properties containing apparent density and fracture toughness were measured by using proper techniques. Experimental results showed that the 3Y-TZP specimen containing $33 wt\%$ of monoclinic zirconia, which was sintered at $1450^{\circ}C$, has the highest fracture toughness value of $11.38 MPa{\cdot}m^{1/2}$ which is three times higher than that of normal 3Y-TZP ceramics.
수소 충전소 영상 정보를 이용한 AI 모델 기반의 실시간 차량 카운팅 시스템에 관한 연구
노은정(Eun-Jung Noh),조범래(Bum-Rae Cho),손병국(Byung-Kuk Son) 한국자동차공학회 2021 한국자동차공학회 부문종합 학술대회 Vol.2021 No.6
본 논문은 수소충전소의 대기 차량 정보 제공올 위해 카메라 영상 정보를 수집하여 AI 모델 기반으로 객체를 검출하고 인식된 차량의 대수를 사용자 어플리게이션에 노출시키는 것을 목적으로 한다. 시스템 구성은 수소 충전소내 영상 정보를 기반으로 하며 객채 검출 모델은 YOLO-v4를 사용하였고, 외부 정보 제공을 위한 API Gateway로 구생하였다. 영상 처리는 전처리 단계에서 관심 영역을 설정 하였으며, 모델 학습을 위한 데이터는 Training data set 과 Test dataset 의 비율을 8:2 로 진행하였다. 이를 통해 충전소 대기 차량, 도로 위를 달리는 차량 그리고 주차된 차량을 구분하여 검출함으로써 정확도가 Pre-train 모델 대비 큰 폭으로 증가하였다.