Effects of Taurine on Generalized Seizure Activity int he Rat Thalamocortical Slice

양성구,이일근,이창중 대한신경과학회 1997 대한신경과학회지 Vol.15 No.6

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.

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 $1400^{\circ}C$.

음낭절증

양성구,양태유,김태진 大韓泌尿器科學會 1979 Korean Journal of Urology Vol.20 No.2

알루미나가 첨가된 Yttria 안정화 Tetragonal Zirconia Polycrystals 소결체의 특성

양성구,정재욱,강종봉 한국세라믹학회 2004 한국세라믹학회지 Vol.41 No.2

고순도 3Y-TZP에 알루미나를 0.3∼l.2wt%까지 첨가하여 attrition milling을 하고 slip-casting하여 시료를 제조하였다. 1390∼151$0^{\circ}C$까지 열처리하여 소결체의 소결특성을 기제적 물성과 미세구조 분석을 통하여 확인하였다. XRD를 이용하여 monoclinic-ZrO$_2$의 생성량을 정량적으로 확인하였으며, 147$0^{\circ}C$ 이장에서 열처리한 시료의 경우 m-ZrO$_2$의 생성으로 밀도의 저하를 보였으며, 비정상 입자성장을 유발하여 경도가 저하되었다. 알루미나의 첨가량이 0.9wt% 미만, 열처리 온도143$0^{\circ}C$에서 microhardness가 1360Hv 이상의 소결체를 제조할 수 있었다. 3Y-TZP containing 0.3∼1.2 wt% of $Al_2$O$_3$ was prepared by slip-casting after attrition milling. The specimen was sintered at 1390∼151$0^{\circ}C$ and mechanical characterization and microstructure analysis were conducted. Monoclinic content of the specimen was calculated by XRD. The apparent density of specimen increased with increasing sintering temperature. While above 1470%, the formation of m-ZrO$_2$ degraded the density. The microhardness of specimen decreased with temperature because monoclinic phase increased wit the grain growth. The specimen containing $Al_2$O$_3$ below 0.9 wt% sintered at 143$0^{\circ}C$ showed the highest microhardness of 1360 Hv.

수열반응을 이용한 미생물 담체용 다공성 세라믹스의 제조

양성구,정승화,강종봉 한국세라믹학회 2003 한국세라믹학회지 Vol.40 No.12

비정질알루미나에 기공형성제를 첨가하여 성형하고 수열반응, 열처리 및 수세를 통해 pellet 형태의 다공성 세라믹 담체를 제조하였다. 기공형성제는 64, 222, 405 $\mu\textrm{m}$의 평균 입경을 가지는 활성탄, 폴리머와 무기염의 변화를 두었으며, 20$0^{\circ}C$에서 24시간동안 수열반응 한 다음 $650^{\circ}C$에서 5시간동안 열처리 및 8$0^{\circ}C$에서 48시간 동안 수세하고, 결정의 생성 및 변화, 기공률, 기공의 분포 및 압축 강도를 측정하였다. 수열반응 이후 활성탄이 첨가된 시편은 boehmite로의 상전이가 이루어졌으나, 기공형성제로 폴리머 및 무기염이 첨가된 시편은 수열 반응 시 비정질알루미나의 aquohydroxy complex gel의 형성을 방해하여 boehmite 결정성장 억제를 가져왔다 활성탄을 기공형성제로 첨가하여 제조한 시편의 경우, 70% 이상의 기공률과 40kgf/$\textrm{cm}^2$ 이상의 강도를 갖는 ${\gamma}$-알루미나의 담체를 제조할 수 있었다. Porous ceramics for microoganism carriers were prepared with amorphous alumina and pore formers by hydrothermal reaction, burn-out and wash-out method. Activated carbon with average size of 67,222, and 405 $\mu\textrm{m}$, organic polymer and inorganic salt were used as pore formers. Specimens were hydrothermally treated at 200$^{\circ}C$ for 24 h, heat-treated at 650$^{\circ}C$ for 5 h, and washed out at 80$^{\circ}C$ for 48 h. The formation of crystalline phase, porosity, pore size distribution and compressive strength were measured. The specimen with activated carbon was transformed to boehmite phase, but organic polymer and inorganic salt inhibited the aquohydroxoy complex gel and crystalline formation. The porous ceramics for microoganism carriers using activated carbon as a pore formers was successfully prepared, which is composed of ${\gamma}$-alumina phase with porosity of above 70 vol% and the compressive strength of 40 kgf/$\textrm{cm}^2$.

Alcohol Impairs Learning of T-maze Task but Not Active Avoidance Task in Zebrafish

양성구,Wansik Kim,Byung-Hee Choi,Hae-Young Koh,Chang-Joong Lee 한국통합생물학회 2003 Animal cells and systems Vol.7 No.4

The aim of this study is to investigate whether alcohol alters learning and memory processes pertaining to emotional and spatial factors using the active avoidance and T-maze task in zebrafish. In the active avoidance task, zebrafish were trained to escape from one compartment to another to avoid electric shocks (unconditioned stimulus) following a conditioned light signal. Acquisition of active avoidance task appeared to be normal in zebrafish that were treated with 1% alcohol for 30 min for 17 days until the end of the behavioral test, and retention ability of learned behavior, tested 2 days later, was the same as control group. In the T-maze task, the time to find a reservoir was compared. While the latency was similar during the 1st training session between control and alcohol-treated zebrafish, it was significantly longer in alcohol-treated zebrafish during retention test 24 h later. Furthermore, when alcohol was treated 30 min after 2nd session without prior treatment, zebrafish demonstrated similar retention ability compared to control. These results suggest that chronic alcohol treatment alters spatial learning of zebrafish, but not emotional learning.

탄소환원질화법을 이용한 AIN Whisker의 합성 I. 불화물 첨가의 영향

양성구,강종봉 한국세라믹학회 2004 한국세라믹학회지 Vol.41 No.2

The properties of AlN made by carbothermal reaction depend on the starting materials, quantity of liquid, the liquid-vapor phase reaction, the N$_2$ flow rate, and the reaction temperature. AlN whisker was synthesized by the VLS and VS methods. Solid ${\alpha}$-A1$_2$O$_3$(AES-11) was carbothermally reduced with carbon black in a high-purity N$_2$ atmosphere with AlF$_3$ to cause whisker grown and additional aluminum liquid to increase whisker yield. Aluminum nitride was perfectly formed at reaction temperatures of 1600$^{\circ}C$. At reaction temperature higher than 1600$^{\circ}C$ the aluminum nitride was completely formed, while the composition remains unaffected. Needle-shaped whiskers formed best at 1600$^{\circ}C$ while higher temperatures disrupted whisker formation. Adding 0 to 15 wt% aluminum to the synthesis favorably affects the microstructure for formation of needle-shaped AlN whisker. Additions over 15 wt% degraded formation of AlN whisker. 탄소환원질화법에 의해 합성된 질화알루미늄의 물성은 출발물질의 종류, 액상$.$기상 반응물질의 양, 분위기 그리고 합성온도에 따라서 많은 차이를 나타내었다 질화알루미늄 합성을 위하여 Al원으로는 $\alpha$-A1$_2$O$_3$를 사용하였고 환원제로는 카본 블랙을 사용하였으며, 기상반응을 유도하기 위하여 AlF$_3$를 사용하여 고순도 질소분위기에서 실험을 행하였다. 또한 액상반응 시 미세구조상의 변화를 확인하기 위하여 금속 알루미늄을 첨가하여 실험을 행하였다. 질화알루미늄이 생성과 침상형 휘스커상의 형상은 1$600^{\circ}C$의 온도에서 가장 잘 나타났으며 열처리 온도의 상승은 오히려 휘스커상의 형성을 방해하고 있음을 보여주었다. 침상형 휘스커의 합성에 가장 큰 영향을 주는 것은 기상반응을 일으키는 AlF$_3$ 첨가이며, AlF$_3$의 첨가량이 증가함에 따라 침상형 휘스커상을 확인하였다. 액상반응을 위한 금속 알루미늄 첨가는 전체의 15wt%까지는 침상형 휘스커가 증가하고 있음을 나타내었으나 l5wt% 이상으로 첨가하는 경우 오히려 휘스커가 감소하는 것으로 나타났다.

탄소환원질화법을 이용한 AlN Whisker의 합성 I. 불화물 첨가의 영향

양성구,강봉상,정승화 한국세라믹학회 2004 한국세라믹학회지 Vol.41 No.2

The properties of AlN made by carbothermal reaction depends on the starting materials, quantity of liquid, the liquid-vapor phase reaction, the N2 flow rate, and the reaction temperature. AlN whisker was synthesized by the VLS and VS methods. Solid α-Al2O3(AES-11) was carbothermally reduced with carbon black in a high-purity N2 atmosphere with AlF3 to cause whisker grown and additional aluminum liquid to increase whisker yield.Aluminum nitride was perfectly formed at reaction temperatures of 1600℃. At reaction temperature higher than 1600℃ the aluminum nitride was completely formed, while the composition remains unaffected. Needle-shaped whiskers formed best at 1600℃ while higher temperatures disrupted whisker formation. Adding 0 to 15 wt% aluminum to the synthesis favorably affects the microstructure for formation of needle-shaped AlN whisker. Additions over 15 wt% degraded formation of AlN whisker. 탄소환원질화법에 의해 합성된 질화알루미늄의 물성은 출발물질의 종류, 액상기상 반응물질의 양, 분위기 그리고 합성온도에 따라서 많은 차이를 나타내었다. 질화알루미늄 합성을 위하여 Al원으로는 α-Al2O3를 사용하였고 환원제로는 카본 블랙을 사용하였으며 기상반응을 유도하기 위하여 AlF3를 사용하였으며 고순도 질소분위기에서 실험을 행하였다. 또한 액상반응 시 미세구조상의 변화를 확인하기 위하여 금속 알루미늄을 첨가하여 실험을 행하였다. 질화알루미늄이 생성과 침상형 휘스커상의 형상은 1600℃의 온도에서 가장 잘 나타났으며 열처리 온도의 상승은 오히려 휘스커상의 형성을 방해하고 있음을 보여주었다. 침상형 휘스커의 합성에 가장 큰 영향을 주는 것은 기상반응을 일으키는 AlF3 첨가이며, AlF3의 첨가량이 증가함에 따라 침상형 휘스커상을 확인하였다. 액상반응을 위한 금속 알루미늄 첨가는 전체의 15 wt%까지는 침상형 휘스커가 증가하고 있음을 나타내었으나 15 wt%이상으로 첨가하는 경우 오히려 휘스커가 감소하는 것으로 나타났다.

산화물의 혼합밀링을 이용한 3Y-TZP의 제조와 특성

양성구 ( Seong Koo Yang ),박미정 ( Mi Jung Park ),강종봉 ( Jong Bong Kang ) 경남대학교 신소재연구소 2005 신소재연구 Vol.17 No.-