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Mn 첨가량 변화에 따른 Tb/Mn이 첨가된 화학양론조성 LiNbO<sub>3</sub> 단결정의 광학적 특성
이성문,신동익,김근영,백승욱,윤대호,Lee, Sung-Mun,Shin, Tong-Ik,Kim, Geun-Young,Back, Seung-Wook,Yoon, Dae-Ho 한국세라믹학회 2004 한국세라믹학회지 Vol.41 No.1
Micro-Pulling Down (${\mu}$-PD) 법을 이용하여 $MnO_2$와 $Tb_4O_7$를 첨가하여 crack. 열 strain 등의 결함이 없는 화학양론조성의 $LiNbO_3$ 단결정을 c-축으로 직경 1.0mm, 길이 25-30mm의 크기로 성장시켰다. Electron Probe Micro Analysis (EPMA)를 이용하여 결정 내에 $MnO_2$와 $Tb_4O_7$이 균일하게 분포되어 있음을 확인하였다. 또한 Fourier Transform-Infrared Spectrophotometer (FT-IR)을 사용하여 OH 흡수밴드를 관찰하였고, 성장된 결정의 $MnO_2$와 $Tb_4O_7$ 첨가에 따른 형광특성의 변화를 측정하였다. Using the Micro-Pulling Down (${\mu}$-PD), $MnO_2$ and $Tb_4O_7$ co-doped crack-free stoichiometric $LiNbO_3$ single crystals were grown in 1.0 mm diameter and 25-30 mm length for c-axis. The homogeneous distributions of $MnO_2$ and $Tb_4O_7$ concentration were confirmed by the Electron Probe Microanalysis (EPMA). Also, the infrared OH absorption band of the single crystals observed by using a Fourier Transform-Infrared Spectrophotometer (FT-IR) at room temperature and the photoluminescence spectra was measured with respect to the $MnO_2$ and $Tb_4O_7$ doping.
Nd\<sub>2</sub>O<sub>3</sub> 첨가에 따른 화학양론조성 LiNbO<sub>3</sub> 단결정의 성장 및 형광특성
서중원,윤석규,이성문,윤대호,Shur, Joong-Won,Yoon, Seok-Gyu,Lee, Sung-Mun,Yoon, Dae-Ho 한국세라믹학회 2002 한국세라믹학회지 Vol.39 No.10
Micro-pulling down법을 이용하여 $Nd_2O_3$가 첨가된 crack 등의 결함이 없는 화학양론조성의 $LiNbO_3$ 단결정을 직경 1 mm, 길이 30∼35 mm의 크기로 성장시켰다. Electron probe micro analysis를 이용하여 결정 내에 $Nd_2O_3$가 균일하게 분포되어있음을 확인하였다. 성장된 결정의 $Nd_2O_3$ 첨가에 따른 흡수 band를 관찰하였고 $Nd_2O_3$ 첨가량 변화에 따른 형광특성의 변화를 측정하였다. Using the micro-pulling down method, $Nd_2O_3$ doped crack-free stoichiometric $LiNbO_3$ single crystals were grown in 1 mm diameter and 30∼35 mm length. The homogeneous distributions of $Nd_2O_3$ concentration were confirmed by the electron probe micro analysis. The absorption and photoluminescence spectra were measured with respect to the $Nd_2O_3$ doping.
서중원,전원남,이성문,양우석,이한영,윤대호,Shur, Joong-Won,Jeon, Won-Nam,Lee, Sung-Mun,Yang, Woo-Seok,Lee, Han-Young,Yoon, Dae-Ho 한국세라믹학회 2002 한국세라믹학회지 Vol.39 No.9
Micro-Pulling Down(${\mu}$-PD)법을 이용하여 직경 1 mm, 길이 30∼35 mm의 $Er_2O_3$와 MgO가 첨가된 화학양론조성 $LiNbO_3$단결정을 성장하였다. 성장된 결정의 $Er_2O_3$와 MgO 첨가에 따른 up-conversion 특성의 변화 및 MgO 첨가량이 광손상에 미치는 영향을 관찰하기 위해 투과율을 측정하였다. 또한 $LiNbO_3$ 단결정 내의 결함유무를 광학현미경을 이용하여 관찰하였고, Electron Probe Micro Analysis(EPMA)를 이용하여 결정 내에 $Er_2O_3$와 MgO가 균일하게 분포되어있음을 확인하였다. Stoichiometric $LiNbO_3$(LN) single crystals of 1 mm diameter and 30∼40 mm length with co-doped the $Er_2O_3$ and MgO were grown by the Micro-Pulling Down(${\mu}$-PD) method. The grown crystals were investigated for the change of the up-conversion property by the $Er_2O_3$ and MgO addition and the optical damage by the MgO concentration. Also, the crystals were studied the defects using the optical microscope and it is identified the homogeneities of the distribution of the $Er_2O_3$ and MgO concentration by the Electron Probe Micro Analysis(EPMA).
주병돈(Byeong-Don Joo),이성문(Sung-Mun Lee),손영명(Young-Myung Son),문영훈(Young-Hoon Moon) 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.11
Hydroforming technology draws attentions of automotive industries due to its advantages such as weight reduction, increased strength, improved quality and reduced tooling cost. Hydroformed automotive parts used as structural components in vehicle body frame often have to be structurally joined at some point. Therefore it is useful if the hydroformed automotive parts can be given a localized attachment flange. In this study, hydroforming process for the flanged tubular parts was proposed. Tube hydroforming experiments were conducted at various conditions. Forming characteristics at various pressure conditions were evaluated. With optimized condition flange was sucessfully formed. The results show that flanged automotive parts can be successfully produced with tube hydroforming.
이혜경(Hyae Kyung Yi),이건엽(Gun Yeop Lee),이성문(Sung Mun Lee),이영선(Young Seon Lee),문영훈(Young Hoon Moon) 대한기계학회 2008 大韓機械學會論文集A Vol.32 No.11
In this study, the characteristics of aluminum tube hydroformed products at different extrusion type and heat treatment conditions were investigated. For the investigation, as-extruded, full annealed and T6-treated Al 6061 tubes at different extrusion type were prepared. To evaluate the hydroformability, free bulge test was performed at room temperature to 300℃. Also mechanical properties of hydroformed products at various pre- and post-heat treatments were estimated by hexagonal prototype hydroforming test at 250℃. And the tensile test specimens were obtained from hexagonal prototype hydroformed tube. As a results, hydroformability of full annealed tube is 5~8% higher than that of extruded and T6-treated tube. The tensile strength and elongation of T6-post heat treated indirect extrusion tube were more than 330㎫ and 12%, respectively. However, T6 pre treated hydroformed product represents high strength, 330㎫ and low elongation, 8%. Therefore, Hydroformability of Al6061 tube showed similar value for both extrusion types. However flow stress of direct tube showed 20~50㎫ lower value than indirect tube.
냉간단조 공정을 적용한 크랭크 샤프트 스프로켓의 기계적 특성 연구
임홍섭(Hong sup Yim),이혜경(Hyae Kyung Yi),이성문(Sung Mun Lee),문영훈(Young Hoon Moon) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.5
Recently, it is attempted to automotive parts by various cold forging methods to meet requirements of mass production and qualities. Compared to hot forged products, cold forged products reveal higher strength and better mechanical properties. In this study, the properties according to forging process type are analyzed for crank shaft sprocket. Cold forged crank shaft sprocket was evaluated surface hardness, micro structure and surface residual stress. Analyzed micro structures and mechanical properties of cold forged crank shaft sprocket were compared with that of conventional hot forging process.