• 한국자기학회지
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• 제7권1호
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• pp.49-54
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• 1997

급속응고된 (N $d_{14.73}$F $e_{78.67}$ $B_{6.60}$)$_{100-x}$ $Co_{x}$(X = 0, 1, 2, 3)리본의 열처리 온도에 따른 자기적 특성, 상변화, 미세조직의 변화에 대해 연구하였다. Co의 첨가로 인해 N $d_{2}$F $e_{14}$B 상의 결정입도가 균일해졌으며, Nd-rich 상들이 입계에 잘 분포됨으로써 보자력($_{i}$ $H_{c}$)이 향상되어 X=2에서 최대 20.3 kOe를 얻었다. 이와 같은 미량의 Co에 의한 보자력 향상의 효과는 고온성형을 요하는 hot-press 및 die-upset에서도 동일하게 나타났으며 최대의 보자력은 X=2에서 hot press시에 16.9 kOe, die-upset 시에 15.12 kOe 이다.

• 한국전기전자재료학회논문지
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• 제20권12호
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• pp.1034-1038
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• 2007

In order to develop the composition ceramics capable of being sintered at low temperature with high piezoelectric properties for multilayer piezoelectric actuator application, PZW-PMN-PZT system ceramics were manufactured according to sintering aid $Li_2CO_3$ addition and their microstructural, dielectric and piezoelectric properties were investigated. The crystal structure of the specimens showed a perovskite phase and no pyrochlore or other second phase was detected. At the sintering temperature of $900\;^{\circ}C,\;0.2\;wt%Li_2CO_3$ added specimen showed a optimum values of kp = 0.562, $d_{33}\;=\;360\;pC/N$ and Qm = 1184, respectively.

• 한국대기환경학회지
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• 제15권3호
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• pp.249-255
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• 1999

We sdudied effect of additives on catalytic activity in thermal catalytic de-NOx process which was composed of thermal reduction, catalytic reduction and catalytic oxidation stage. Pd-Pt/${\gamma}$-$Al_2O_3$ catalysts with the addition of transition metals(Co, Cu, Fe, Ni, W, Zn, Zr) and rare earth metals(Ce, Sr) were prepared by the conventional washcoating method. Those catalysts were characterized by CO pulse chemisorption, ICP, $N_2$ adsorption, SEM and XRD. The effect of catalyst additives on NOx removal for diesel emission was studied in thermal catalytic de-NOx process at reduction temperature(350~50$0^{\circ}C$), space velocity(5,000~20,000 $hr^{-1}$) and the engine load(0~120kW). The concentraton of CO, $CO_2$, NO and $NO_2$ in the exhaust gas increased with the engine load. On the other hand the concentration of $O_2$ decreased. The de-NOx activityof all prepared catalysts increased with respect to high CO and low $O_2$ level in the thermal reduction stage of the process. Insertion of Ce to Pt-Pd/${\gamma}$-$Al_2O_3$ catalyst showed the best activity of all the catalysts under these experimental conditions. De-NOx catalysts are effective to remove CO in addition to NOx in the catalytic reduction stage.

• 한국농공학회논문집
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• 제53권1호
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• pp.63-69
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• 2011

The green algae Scenedesmus acuminatus was cultured in different media: animal wastewater and an artificial culture medium in order to evaluate potential use for tertiary treatment. The experiments were conducted with air flowrate 1~2 L/min at $28{\sim}30^{\circ}C$. The nitrogen and phosphorus showed very similar removal efficiencies (68~77 % and 69~80 % for nitrogen and phosphorus respectively). The optimal fed period was estimated as three days in the semi-continuous experiment. The effects of $CO_2$ (4.5 %) injection on nutrient uptake from animal wastewater (biological treatment effluent) were compared to an air injection under the same conditions of light and photoperiod. The uptake rates of nutrient with air injection were observed 0.009 gN/gChl-a/day, 0.028 gN/gChl-a/day and T-P 0.003 gP/gChl-a/day for nitrate, total nitrogen and phosphorus respectively. The rates were enhanced by addition of $CO_2$ to 0.026 gN/gChl-a/day, 0.076 gN/gChl-a/day and T-P 0.018 gP/gChl-a/day. This study establishes that $CO_2$ addition during nutrient deprivation of microalgal cells may accelerate tertiary wastewater treatment.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2012년도 춘계 학술논문 발표대회
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• pp.43-45
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• 2012

As a part of recent CO₂ emission reduction studies in the concrete industry with active use of concrete admixtures with low basic unit of CO₂ emission such as blast furnace slag (BFS), basic unit of CO₂ emission by SBFS was computed in order to assess CO₂ emission by reinforced concrete building with smart blast furnace slag (SBFS). In addition, SBFS concrete was applied to the subject building for assessment of CO₂ emission during material production step among construction steps. Life cycle CO₂ emission assessment on the subject building was classified into 7cases according to mix ratio of BFS and SBFS.

• 대한환경공학회지
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• 제33권8호
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• pp.553-563
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• 2011

이 연구는 대기 중 $CO_2$ 농도의 증가 및 질소 농도 조건에 따라 토양의 생물학적 유기물 분해과정의 변화 양상을 살펴보고, 담수 습지 토양에서 주로 일어나는 탈질, 철환원, 메탄환원 반응이 토양 유기물 분해에서 차지하는 중요도를 파악하여, 습지가 대기 중 온실가스 농도 변화에 미치는 영향을 예측해 보고자 하였다. 탈질률, 메탄환원률은 $CO_2$ 농도 변화, 식물 유무, 질소 유무에 따라 통계적으로 유의한 차이를 보였고(p < 0.05), 철환원률의 경우 질소의 유무에 따른 변화만이 유의한 차이를 보였다. $CO_2$ 농도가 증가함에 따라 메탄환원이 유기물을 분해하는 함께 질소가 첨가될 경우에도 메탄환원률의 비율이 높게 나타나 기후변화에 따른 담수 퇴적물의 혐기성 물질대사반응은 메탄환원이 가장 주요 반응임을 알 수 있다. 기후변화는 또한 분해되어지는 유기물의 총량도 증가시켜 전체적으로 $CO_2$ 농도가 높은 경우, 특히 $CO_2$ 농도가 높으면서 질소가 첨가된 경우에 단위시간당 단위무게의 토양에서 분해되어지는 유기물의 양이 많아짐을 알 수 있다. 연구의 결과로부터 기후변화는 습지 토양내 유기물의 혐기적 분해의 속도를 증가시켜 분해되어지는 유기물의 양을 증가시키므로 분해의 산물로 발생되는 온실가스($CO_2$, $N_2O$, $CH_4$ 등)의 대기 방출을 증진시켜 기후변화에 순영향(positive effect)를 줄 수 있으리라 판단된다.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2019년도 추계 학술논문 발표대회
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• pp.38-39
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• 2019

Environmental problems caused by GHG emitted by various industries are emerging around the world, and accordingly, relevant regulations are being applied by countries around the world. Korea is operating a carbon credit system that trades GHG in industry for money, which is expected to be applied to the construction industry. In addition, construction equipment using fossil fuels accounts for the largest portion of $CO_2$ emissions in the construction industry, and the importance of $CO_2$ reduction and prediction is increasing. However, there is a lack of data on the directly measured $CO_2$ emissions of construction equipment and there is no accurate methodology for measuring methods. Therefore, in this study, independent variables were derived based on the $CO_2$ emission data. In addition, multiple linear regression is performed for each independent variable to derive a predictive model of carbon dioxide emission by work type of construction equipment. It is expected that the construction process plan based on environmental factors in the construction industry can be established in the future.

• 한국세라믹학회지
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• 제46권3호
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• pp.323-329
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• 2009

Influences of ceramic filler types and dose on the sintering, phase evolution, and dielectric properties of ceramic/CaO-$Al_2O_3-SiO_2$ glass composites were investigated. All of the specimens were sintered at $900^{\circ}C$ for 2 h, which conditions are required by the lowtemperature co-firing ceramic (LTCC) technology. Ceramic fillers of $Al_2O_3,\;SiO_2$, kaolin, and wollastonite were used. The addition of $Al_2O_3$ filler yielded the crystalline phases of alumina and wollastonite, and the densification over 95% of the relative density was achieved up to 50 wt% addition of the filler. For the cases of the fillers of $SiO_2$, kaolin, and wollastonite, crystalline phases of quartz, mullite, and wollastonite formed, while the densification decreased monotonically with the filler addition. In overall, all the investigated fillers with 10 wt% addition resulted in a reasonable sintering (over 95 %) and low dielectric constants (less than 6), demonstrating the feasibility of the investigated composites for application to a LTCC substrate material with a low dielectric constant.

• 한국대기환경학회지
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• 제17권5호
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• pp.407-414
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• 2001

In this study, the absorption kinetics of $CO_2$onto a mixture of AMP (2-amino-2-methyl-1-propanol) MEA (monoethanolamine) water were investigated at 30 and 4$0^{\circ}C$ using a packed absorption tower. Solubility and absorption rate of $CO_2$into alkanolamine solutions and optimal condition of $CO_2$absorption process were investigated. The experimental conditions are as follows; temperature of 30 and 4$0^{\circ}C$, gas flow rate of 3ι/min for the absorption tower, and liquid flow rate of 0.1ι/min. Feed gas was a mixture of 85% $N_2$and 15% $CO_2$. The experimental results showed that AMP had greater solubilities and faster absorption rates than MEA and DEA. In addition, MEA had the fastest initial reaction rate. To improve the properties of AMP which have low initial reaction rate and high cost, AMP was used with MEA. The mixing ratio was also changed in constant total molarity of 1,2,3 and 4. The experimental results can be summarized as follows: (1) in solubility experiment, the addition of MEA in constant total polarity decreased the solubility of $CO_2$in AMP/MEA mixture. (2) from 0 to about 0.3 in mixing ratio, the solubility of $CO_2$in AMP/MEA mixture had little differences compared with the sum of solubility of AMP only and solubility of MEA only . (3) mixing ratio of 0.3 was found to be an optimal point with the fastest $CO_2$absorption rate.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2002년도 제24회 KOSCO SYMPOSIUM 논문집
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• pp.185-191
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• 2002

The influence of N2 addition on soot formation, flame temperature and NOx emissions is investigated experimentally with methane fuel co-flow diffusion flames. The motivation of the present investigation is the differences in NOx reduction reported between fuel-side and oxidizer-side introduction of N2. To determine the influence of dilution alone, fuel was diluted with nitrogen while keeping the adiabatic flame temperature fixed by changing the temperature of the reactants. And to see the thermal effect only, air was supplied at different temperature without N2 addition. N2 addition into fuel side suppressed the soot formation than the case of oxidizer-side, while flame temperature enhanced the soot formation almost linearly. These results reveals the relative influences of the thermal, concentration effects of N2 additives on soot formation In accordance with experimental study, numerical simulation using CHEMKIN code was carried out to compare the temperature results with those acquired by CARS measurement, and we could find that there is good agreement between those results. Emission test revealed that NOx emissions were affected by not only flame temperature but also N2 addition.