• 한국토양비료학회지
• /
• 제49권2호
• /
• pp.132-137
• /
• 2016

Field monitoring was performed to evaluate the chemical properties of 260 paddy soils every 4 years from 1999 to 2015 in Gyeongnam province. Soil chemical properties, including soil pH, electrical conductivity, amount of organic matter (OM), available phosphate ($P_2O_5$), exchangeable potassium (K), calcium (Ca), magnesium (Mg) and sodium (Na), and available silicate ($SiO_2$) were analyzed. In 2015, the average values of pH, OM, available $P_2O_5$, exchangeable K, Ca, and Mg, and available $SiO_2$ was 5.8, $30g\;kg^{-1}$, $222mg\;kg^{-1}$, $0.37cmol_c\;kg^{-1}$, $6.5cmol_c\;kg^{-1}$, and $1.4cmol_c\;kg^{-1}$, $252mg\;kg^{-1}$, respectively. The frequency distribution within optimum range of paddy soils was 49.2%, 20.8%, 18.5%, and 5.8% for soil pH, OM, available $P_2O_5$, and available $SiO_2$, respectively. The available $P_2O_5$ concentrations in 2015 was excess level with portion of 58% and did not alter significantly during the experimental period. Although the average of available $SiO_2$ concentration has tended to increase with every year, the insufficient proportion of available $SiO_2$ concentration in 2015 was 48%. These results indicated that a balanced management of soil chemical properties can properly control the amount of fertilizer applied for sustainable agriculture in paddy field.

• 한국세라믹학회지
• /
• 제31권10호
• /
• pp.1169-1175
• /
• 1994

Five Al2O3/SiC/metal composites with four different particle sizes of green SiC abrasive grains are grown by the directed oxidation of an commercially available Al-alloy. Oxidation was conducted in air at 100$0^{\circ}C$, 96 hours long. Slip casted SiC-fillers were placed on the alloy or SiC powder deposited up to the required layer thickness. Their microstructures are described and measurements of density, elastic constants, frexural strength, fracture toughness and work of fracture are reported. The results are compared with those of commercial dense sintered Al2O3. The properties of produced materials have a strong relationship to not only the properties of Al2O3, SiC, Al and Si but also to the phase share and phase distribution. The composite materials are dense (0.5% porosity), tough (KIC = 3.4~6.4 MPa{{{{ SQRT { m} }}), strong ({{{{ sigma }}B = 170~345 MPa) and reasonably shrinkage free producible. The reinforcements is attained mainly through the plastic deformation of ductile metal phase.

• 한국토양비료학회지
• /
• 제36권6호
• /
• pp.407-416
• /
• 2003

규산질 비료는 산성 토양의 개량 효과와 함께 병충해 발생 억제 효과를 나타내므로 농약 사용량을 줄일 수 있어 안전농산물의 생산을 유도할 수 있는 자재로 판단되고 있으며 일부 참외의 수량 증대와 상품성을 향상시킬 수 있는 것으로 알려져 있다. 그러나 현재 참외를 비롯한 과채류에 대하여 규산질 비료의 시용효과가 검정되어있지 않고 또한 적정 시용 기준이 설정되어 있지 못한 상태에서 농가별로 토양 유효규산 함량을 고려하지 않고 임의로 규산질 비료를 사용하고 있다. 본 연구에서 조사된 결과를 보면 참외 재배 포장에서 1 N NaOAc로 추출할 경우 최고 $500mg\;SiO_2\;kg^{-1}$ 수준까지 유효규산이 축적되어 있으며, $200mg\;SiO_2\;kg^{-1}$ 수준의 유효규산을 함유하고 있는 토양에 대한 규산질 비료의 시용은 참외의 생육이나 수량 증대에 영향을 미치지 못하는 것으로 나타났다. 또한 1 N NaOAc로 추출한 토양 유효규산 함량이 $100mg\;SiO_2\;kg^{-1}$ 이상인 경우 참외의 규산 흡수가 더 이상 증가하지 않는 것으로 나타났다. 따라서 토양 유효규산 함량을 무시한 과다 규산질 비료의 시용은 pH와 EC의 증가에 따른 부작용을 유발할 가능성도 높으므로 농가지도를 통하여 시용량이 적절히 조절되어야 할 것이며, 참외를 비롯한 밭작물에 대한 적정 토양 유효규산 함량과 시비 기준 확립을 위한 연구가 더욱 필요할 것으로 판단된다.

• 한국정보디스플레이학회:학술대회논문집
• /
• 한국정보디스플레이학회 2005년도 International Meeting on Information Displayvol.II
• /
• pp.1338-1342
• /
• 2005

We have synthesized an $Eu^{2+}$-activated $Sr_3MgSi_2O_8$ blue phosphor and $Ba_2SiO_4$ green phosphor and $Ba^{2+}$ co-doped $Sr_3SiO_5$ red phosphor investigated an attempt to develop white LEDs by combining it with a GaN blue LED $chip(\lambda_{em}=405 nm)$. Three distinct emission bands from the GaN-based LED and the $(Sr_3MgSi_2O_8:Eu\; +\; Ba_2SiO_4:Eu\; +\; Ba^{2+}\; co-doped\; Sr_3SiO_5:Eu)$ phosphor are clearly observed at 460nm, 520 nm and at around 600 nm, respectively. These three emission bands combine to give a spectrum that appears white to the naked eye. Our results show that GaN (405 nm chip)-based $(Sr_3MgSi_2O_8:Eu\; +\; Ba_2SiO_4:Eu\; +\; Ba^{2+}\; co-doped\; Sr_3SiO_5:Eu) exhibits a better luminous efficiency than that of the industrially available product InGaN (460 nm chip)-based YAG:Ce.

• 한국대기환경학회지
• /
• 제20권3호
• /
• pp.291-302
• /
• 2004

The CuO/$3AL_2O_3{\cdot}2SiO_2$ catalyst impregnated ceramic candle filters for nitrogen oxides removal were prepared by porous mullite($3AL_2O_3{\cdot}2SiO_2$) support and CuO catalyst deposited on this support to achieve uniformly dispersed CuO deposition, which are impregnated into the pores of available alumino-silicate ceramic candle filter. The CuO/3$AL_2O_3{\cdot}2SiO_2$ catalyst impregnated ceramic candle filters were characterized by XRD, BET, air permeability, pore size, SEM and catalytic tests in the reduction of NOx by NH$_3$. The observed effects of CuO/3$AL_2O_3{\cdot}2SiO_2$ impregnated ceramic candle filters in SCR reaction are as follows : (1) when the content of CuO catalyst increased further, activity of NO increased. (2) NO conversion at first increased with temperature and then decreased at high temperatures (above 40$0^{\circ}C$), possibly due to the occurrence of the ammonia oxidation reaction. (3) In pilot plant test for 3 months, NO conversion was greater than 90%.

• 대한화학회지
• /
• 제56권4호
• /
• pp.478-483
• /
• 2012

We successfully synthesized $Fe_3O_4/SiO_2$ nanoparticles with ultrathin silica layer of $1.0{\pm}0.5$ nm that was fine controlled by changing concentration of $Fe_3O_4$. Among various reaction conditions for silica coating, increasing concentration of $Fe_3O_4$ was more effective approach to decrease silica thickness compared to water-to-surfactant ratio control. Moreover, we found that concentration of the 1-octanol is also important factor to produce the homogeneous $Fe_3O_4/SiO_2$ nanoparticles. The present approach could be available to apply on preparation of other core/shell nanoparticles with ultrathin silica layer.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1987년도 전기.전자공학 학술대회 논문집(I)
• /
• pp.461-464
• /
• 1987

With the fabrication of Al-$Al_2O_3$-n(p) type Si devices, the analysis and measurement of various characteristics, this study presented the electric physical property theory for the charge distribution of MAS device $Al_2O_3$ films, and inquired out the devices available. In order to study them, Al-(450A)$Al_2O_3$-n(p) type Si was the main objects in the study. They were examined through carrier injection, C-V curves of devices on time, ${\Delta}V_{FB}$-t curves, I-V curves and $Al_2O_3$ film's breakdown characteristics.

• 한국토양비료학회지
• /
• 제3권1호
• /
• pp.17-21
• /
• 1970

답(畓)에 시용(施用)한 규산(珪酸)과 인산(燐酸)의 영향(影響)을 조사(調査) 연구(硏究)하기 위해서 직경(直徑) 15cm의 Petri dish에 200grs의 풍건세토(風乾細土)와 3 수준(水準)의 규산(珪酸) 인산(燐酸) 처리(處理)를 하고 질소(窒素)와 가리(加里)는 동일량(同一量)을 매회(每回) 처리(處理)하는 9개구(個區)를 설치(設置) 농림(農林) 25호(號)를 100립(粒) 씩 최아(催芽) 낙종(落種)하여 5회(回) 계속(繼續) 재배(栽培)하고 식물체분석(植物體分析) 및 토양분석(土壤分析)을 실시(實施)한 성적(成績)을 분석(分析) 평가(評價)한 결과(結果)는 다음과 같다. 1. 인산(燐酸)의 흡수량(吸收量)이 많을수록 수도묘(水稻苗)의 건물중(乾物重)은 현저히 증대(增大)하였으나 규산(珪酸)의 흡수량(吸收量) 증대(增大)로 건물중(乾物重)은 감소(減少)하는 경향(傾向)을 보였다. 2. 시험(試驗) 후(後) 토양(土壤)의 유효 인산함량(燐酸含量)이 많은 것일수록 식물체중(植物體中)의 규산함량(珪酸含量) 및 흡수량(吸收量)은 감소(減少)하는 경향(傾向)이며 $SiO_2/P_2O_5$의 비율(比率)은 현저히 감소(減少)되었다. 3. 규회석(珪灰石) 시용(施用)으로 시험(試驗) 후(後) 토양중(土壤中)의 유효 규산(珪酸), 석회(石灰) 함량(含量)과 식물체(植物體) 중(中)의 규산(珪酸) 함량(含量), 규산(珪酸) 흡수량(吸收量) $SiO_2/P_2O_5$의 비율(比率)은 현저히 증대(增大)되었으며 4. 토양중(土壤中)의 유효규산함량 자체(自體)의 증대(增大) 보다도 석회함량(石灰含量)의 증대(增大)가 식물체(植物體) 중(中) 규산함량(珪酸含量) 규산(珪酸) 흡수량(吸收量) 및 $SiO_2/P_2O_5$ 비(比)의 증대(增大)와 더욱 높은 상관(相關)을 보였다. 5. 식물체중(植物體中)의 $SiO_2/P_2O_5$의 비율(比率)을 조절(調節)하기 위해서는 토양중(土壤中)의 $SiO_2/P_2O_5$의 비율(比率)을 조절(調節)하므로서 가능(可能)하며 6. 식물체중(植物體中)의 $SiO_2/P_2O_5$의 비율(比率)(y)은 시험(試驗) 후(後) 토양중(土壤中)의 유효 $SiO_2/P_2O_5$의 비(比)(x)와 $y=0.665+1.420x-0.0825x^2$의 회귀관계(回歸關係)가 있으며 적중율(適中率)($r^2$)은 82%였다.

• 한국정보디스플레이학회:학술대회논문집
• /
• 한국정보디스플레이학회 2004년도 Asia Display / IMID 04
• /
• pp.636-639
• /
• 2004

We have synthesized a $Eu^{2{\cdot}}$ -activated $Sr_3MgSi_2O_8$ blue phosphor and $Ba^{2{\cdot}}$ co-doped $Sr_2SiO_4$ yellow phosphor investigated an attempt to develop white LEDs by combining it with a GaN blue LED chip. Three distinct emission bands from the GaN-based LED and the ($Sr_3MgSi_2O_8$:Eu + $Ba^{2{\cdot}}$ co-doped $Sr_2SiO_4$:Eu) phosphor are clearly observed at 405nm, 455 nm and at around 540 nm, respectively. These three emission bands combine to give a spectrum that appears white to the naked eye. Our results show that GaN (405 nm chip)-based ($Sr_3MgSi_2O_8$:Eu + $Ba^{2{\cdot}}$ co-doped $Sr_2SiO_4$:Eu) exhibits a better luminous efficiency than that of the industrially available product InGaN (460 nm chip)-based YAG:Ce.

• 한국재료학회지
• /
• 제20권9호
• /
• pp.463-466
• /
• 2010

We studied the initial reaction mechanism of Zn precursors, namely, di-methylzinc ($Zn(CH_3)_2$, DMZ) and diethylzinc ($Zn(C_2H_5)_2$, DEZ), for zinc oxide thin-film growth on a Si (001) surface using density functional theory. We calculated the migration and reaction energy barriers for DMZ and DEZ on a fully hydroxylized Si (001) surface. The Zn atom of DMZ or DEZ was adsorbed on an O atom of a hydroxyl (-OH) due to the lone pair electrons of the O atom on the Si (001) surface. The adsorbed DMZ or DEZ migrated to all available surface sites, and rotated on the O atom with low energy barriers in the range of 0.00-0.13 eV. We considered the DMZ or DEZ reaction at all available surface sites. The rotated and migrated DMZs reacted with the nearest -OH to produce a uni-methylzinc ($-ZnCH_3$, UMZ) group and methane ($CH_4$) with energy barriers in the range of 0.53-0.78 eV. In the case of the DEZs, smaller energy barriers in the range of 0.21-0.35 eV were needed for its reaction to produce a uni-ethylzinc ($-ZnC_2H_5$, UEZ) group and ethane ($C_2H_6$). Therefore, DEZ is preferred to DMZ due to its lower energy barrier for the surface reaction.