BaSn(BO3)2 세라믹스의 저온소결 및 유전 특성

남명화,남산,남중희,여동훈,김효태,황준철,김종희 한국세라믹학회 2006 한국세라믹학회지 Vol.43 No.2

Dolomite type BaSn(BO3)2 ceramics with rhombohedral crystal structure has been synthesized via solid state reaction route. Dielectric properties were measured for the samples sintered at 1050℃ 1200℃ for 4 hours in air. Dielectric constant, loss tangent, and temperature coefficient were increased with sintering temperature due to the evolution of BaSnO3, secondary, phase. Optimum dielectric properties were obtained at the BaSn(BO3)2 ceramics sintered at 1100℃. CuO/Bi2O3 was added to BaSn(BO3)2 ceramics to lower the sintering temperature for LTCC application, then Co and Fe-based coloring agents were added for colorizing the LTCC tape. Typical dielectric properties of BaSn(BO3)2 ceramics with 5wt.% CuO/Bi2O3 and 3wt.% Co-coloring agent that sintered at 900℃ were r = 9.89, tan=0.92 10-3, and TCC = 112ppm/℃. Thus obtained LTCC tape was co-fired with Ag paste for compatibility test and revealed no sign of Ag reaction with the ceramics.

CaZr(BO₃)₂ 세라믹스의 마이크로웨이브 유전특성

남명화,김효태,김종희,남산,Nam, Myung-Hwa,Kim, Hyo-Tae,Kim, Jong-Hee,Nahm, Sahn 한국세라믹학회 2007 한국세라믹학회지 Vol.44 No.5

The microstructure and microwave dielectric properties of dolomite type borates, $CaZr(BO_3)_2$ ceramics prepared by conventional mixed oxide method were explored. The sintering temperature of $CaZr(BO_3)_2$ ceramics could be reduced from $1150^{\circ}C\;to\;925^{\circ}C$ with little amount of sintering additives. Microwave dielectric properties of 3 wt% $Bi_2O_3-CuO$ added $CaZr(BO_3)_2$ ceramics sintered at $925^{\circ}C$ were $K{\approx}10.4,\;Q{\times}f{\approx}80,000GHz\;and\;TCF{\approx}+2ppm/^{\circ}C$. Thus obtained LTCC tape was co-fired with Ag paste for compatibility test and revealed no sign of Ag reaction with the ceramics. Therefore, $CaZr(BO_3)_2$ ceramics is considered as a possible candidate material for low temperature co-fired multilayer devices.

瞼球摩擦이 眼炎症에 미치는 影響

南明和,丁海崙 고려대학교 의과대학 1986 고려대 의대 잡지 Vol.23 No.1

The patients with various ocular diseases frequently rub their eyes. The author studied the effects of eye rubbing on the histologic characteristics cf the conjunctiva. Each one eye of twenty albino rabbits were rubbed on the upper lid with finger for five-minute period, and the unrubbed contralateral eye served as a control. The upper tarsal conjunctivas were taken immediately, at four. eight, and twenty-four hours after the rubbing. After fixation of specimens in Kernovsky's fixative, the tissues were processed for preparation of Epon block and one-micron section. Sections were stained with alkaline Giemsa and toluidine blue arid light microscopic examination was performed. The results were as followings : Immediately after rubbing, the conjunctival epithelium was disrupted and the mast cells became degranulation. At four hours, there was moderate infiltration of neutrophils. At eight arid twenty-four hours after rubbing, infiltration of macrophages was occurred and increased in cumber. But there was no significant changes in numbers of lymphocytes, plasma cells, and eosinophils. This study revealed that eye rubbing induces conjunctival erythema and alteration in the inflammatory cell infiltrate, and therefore eye rubbing map influence the course and severity of ocular diseases.

CaZr(BO3)2 세라믹스의 마이크로웨이브 유전특성

남명화,김효태,남산,김종희 한국세라믹학회 2007 한국세라믹학회지 Vol.44 No.5

The microstructure and microwave dielectric properties of dolomite type borates, CaZr(BO3)2 ceramics prepared by conventional mixed oxide method were explored. The sintering temperature of CaZr(BO3)2 ceramics could be reduced from 1150 o C to 925 o C with little amount of sintering additives. Microwave dielectric properties of 3 wt% Bi2O3-CuO added CaZr(BO3)2 ceramics sintered at 925 o C were K≈10.4, Q×f ≈80,000 GHz and TCF≈+2 ppm/ o C. Thus obtained LTCC tape was co-fired with Ag paste for compatibility test and revealed no sign of Ag reaction with the ceramics. Therefore, CaZr(BO3)2 ceramics is considered as a possible candidate material for low temperature co-fired multilayer devices.

BaSn(BO₃)₂세라믹스의 저온소결 및 유전특성

남명화,김효태,황준철,남중희,여동훈,김종희,남산,Nam, Myung-Hwa,Kim, Hyo-Tae,Hwang, June-Cheol,Nam, Joong-Hee,Yeo, Dong-Hoon,Kim, Jong-Hee,Nahm, Sahn 한국세라믹학회 2006 한국세라믹학회지 Vol.43 No.2

Dolomite type $BaSn(BO_3)_2$ ceramics with rhombohedral crystal structure has been synthesized via solid state reaction route. Dielectric properties were measured for the samples sintered at $1050\~1200^{\circ}C$ for 2 h in air. Dielectric constant, loss tangent, and temperature coefficient were increased with sintering temperature due to the evolution of $BaSnO_3$, secondary, phase. Optimum dielectric properties were obtained at the $BaSn(BO_3)_2$ ceramics sintered at $1100^{\circ}C.\;CuO/Bi_2O_3$ was added to $BaSn(BO_3)_2$ ceramics to lower the sintering temperature for LTCC application, then Co and Fe-based coloring agents were added for colorizing the LTCC tape. Typical dielectric properties of $BaSn(BO_3)_2$ ceramics with $5 wt\%\;CuO/Bi_2O_3\;and\;3wt\%$ Co-coloring agent that sintered at $900^{\circ}C$ were $\varepsilon_r=9.89,\;tan{\delta}=0.92\times10^{-3},\;and\;TCC=112ppm/^{\circ}C$. Thus obtained LTCC tape was co-fired with Ag paste for compatibility test and revealed no sign of Ag reaction with the ceramics.

생체 시료 중 아세틸콜린 및 콜린에 대한 효소-분광학적 정량분석

남명화(Myung Hwa Nam),이성호(Sung-Ho Lee),김기택(Ketack Kim),한영희(Younghee Hahn) 대한약학회 2012 약학회지 Vol.56 No.4

In order to determine acetylcholine and choline in the biological samples, the specific enzymes of acetylcholinesterase (AChE) and choline oxidase (ChO), which utilize acetylcholine and choline as substrates, were employed to convert substrates to H2O2. The produced H2O2 was coupled to 4-aminoantipyrine/phenol with peroxidase (PO) yielding quinoneimine dye which was measured at 508 nm. In the present enzymatic spectrophotometric analysis the product at the equilibrium state was measured considering accuracy, precision, time and cost of the analysis. The developed analytical method yielded good linearity (calibration curve; A508=9534[acetylcholine]+0.009, correlation coefficient (R2); 0.999) with detection limit of 1.11×10-7 M, reasonable precision (relative standard deviation; 0.10~1.62% at 2.5×10-6 M~1.25×10-4 M) and accuracy (relative error; -0.24~0.97% at 4.13×10-6M~1.01×10-4 M) for acetylcholine chloride standard solution. The concentrations of acetylcholine and choline in human serum were found as 3.20×10-5 M and 1.14×10-4 M, respectively. The brain tissues of Sprague-Dawley strain rat contained 9.82 μg/g of acetylcholine and 6.53 μg/g of choline in the cerebrum, while 7.37 μg/g of acetylcholine and 5.34 μg/g of choline in the cerebellum.

분무 열 분해법을 이용한 Zn₂SiO₄ : Mn 나노 형광체의 광학적 특성에 관한 연구

남상훈(Sang-Hun Nam),김명화(Myoung-Hwa Kim),이상덕(Sang Duck Lee),부진효(Jin-Hyo Boo) 한국진공학회(ASCT) 2010 Applied Science and Convergence Technology Vol.19 No.1

PDP를 비롯한 형광체를 이용하는 디스플레이 분야에서 현재 마이크로미터(μ-meter) 이상의 크기를 갖는 기존의 벌크(bulk) 형광체를 능가하는 성능과 새로운 물성을 나타내는 나노형광체(nanophosphor) 개발 및 응용에 대한 연구가 절대적으로 필요한 시점이다. 따라서 본 실험에서는 나노 사이즈의 평균 입자 크기를 갖는 구형의 Zn₂SiO₄:Mn 형광체 입자를 초음파 분무열 분해(ultrasonic spray pyrolysis) 방법을 이용하여 합성하였다. 구형의 형광체 입자의 크기는 분무 장치의 droplet separator를 도입하여 조절하였다. 2 ㏖%의 망간을 도핑하여 합성한 Zn₂SiO₄:Mn 입자는 시간이 지남에 따라 감소되고, 최근에 고상에서 합성하여 상용화된 물질에 비교할 수 있을 만한 빛 방출의 세기를 가졌다. 형광체 입자의 크기는 무기질 염의 농도가 0에서 5 M로 증가함에 따라 1 ㎛에서 0.2 ㎛로 감소하였다. 0.5 M 이상의 농도의 전구체 용액에서 얻어진 형광체 입자의 빛 방출은 상용화되어 있는 물질과의 비교를 통해 알아보았다. Spherical shape Zn₂SiO₄:Mn phosphor particles with the mean particle size from submicron to micron sizes were prepared by ultrasonic spray pyrolysis method. A droplet separator was introduced to control the size distribution of the phosphor particles with spherical shape. The Zn₂SiO₄:Mn phosphor particles with 2 ㏖% doping concentration of manganese have decay time and have photoluminescence intensities comparable with those of the latest commercial product prepared by the solid state reaction method. The size of the phosphor particles was decreased from 1 to 0.2 micrometers as the inorganic salt solution concentration was changed from 0 to 5 M. The phosphor particles prepared from the solutions above 0.5 M have photoluminescence intensities comparable with that of the latest commercial product.

기획좌담 : 연극 작업에서의 아시아적 교류, 그 현황과 문제점을 진단한다

김명화,심재찬,손정우,오수경,타다쥰노스케,박장렬,전수환,김병춘,성기웅,남지수,이상민 한국연극평론가협회 2008 연극평론 Vol.49 No.-

분무 열 분해법을 이용한 Zn₂SiO₄ : Mn 나노 형광체의 광학적 특성에 관한 연구

남상훈,김명화,이상덕,부진효,Nam, Sang-Hun,Kim, Myoung-Hwa,Lee, Sang-Duck,Boo, Jin-Hyo 한국진공학회 2010 Applied Science and Convergence Technology Vol.19 No.1

PDP를 비롯한 형광체를 이용하는 디스플레이 분야에서 현재 마이크로미터($\mu}$-meter) 이상의 크기를 갖는 기존의 벌크(bulk) 형광체를 능가하는 성능과 새로운 물성을 나타내는 나노형광체(nanophosphor) 개발 및 응용에 대한 연구가 절대적으로 필요한 시점이다. 따라서 본 실험에서는 나노 사이즈의 평균 입자 크기를 갖는 구형의 $Zn_2SiO_4:Mn$ 형광체 입자를 초음파 분무열 분해(ultrasonic spray pyrolysis) 방법을 이용하여 합성하였다. 구형의 형광체 입자의 크기는 분무 장치의 droplet separator를 도입하여 조절하였다. 2 mol%의 망간을 도핑하여 합성한 $Zn_2SiO_4:Mn$ 입자는 시간이 지남에 따라 감소되고, 최근에 고상에서 합성하여 상용화된 물질에 비교할 수 있을 만한 빛 방출의 세기를 가졌다. 형광체 입자의 크기는 무기질 염의 농도가 0에서 5 M로 증가함에 따라 $1\;{\mu}m$에서 $0.2\;{\mu}m$로 감소하였다. 0.5 M 이상의 농도의 전구체 용액에서 얻어진 형광체 입자의 빛 방출은 상용화되어 있는 물질과의 비교를 통해 알아보았다. Spherical shape $Zn_2SiO_4:Mn$ phosphor particles with the mean particle size from submicron to micron sizes were prepared by ultrasonic spray pyrolysis method. A droplet separator was introduced to control the size distribution of the phosphor particles with spherical shape. The $Zn_2SiO_4:Mn$ phosphor particles with 2 mol% doping concentration of manganese have decay time and have photoluminescence intensities comparable with those of the latest commercial product prepared by the solid state reaction method. The size of the phosphor particles was decreased from 1 to 0.2 micrometers as the inorganic salt solution concentration was changed from 0 to 5 M. The phosphor particles prepared from the solutions above 0.5 M have photoluminescence intensities comparable with that of the latest commercial product.

Synthesis of ZnO nanoparticles and their photocatalytic activity under UV light

남상훈,김명화,부진효 한국진공학회 2011 한국진공학회 학술발표회초록집 Vol.40 No.0