• 한국안전학회지
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• 제31권4호
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• pp.48-54
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• 2016

The prediction of various emissions from coal combustion is an important subject of researchers and engineers because of environmental consideration. Therefore, the development of the models for predicting pollutants very fast has received much attention from international research community, especially in the field of safety assessment. In this work, response surface method was introduced as a design of experiment, and the database for RSM was set with the numerical simulation of a drop tube furnace (DTF) to predict the spatial distribution of pollutant concentrations as well as final ones. The distribution of carbon dioxide in DTF was assumed to have Boltzman function, and the resulted function with parameters of a high $R^2$ value facilitates predicting an accurate distribution of $CO_2$. However, CO distribution had a difference near peak concentration when Gaussian function was introduced to simulate the CO distribution. It might be mainly due to the anti-symmetry of the CO concentration in DTF, and hence Extreme function was used to permit the asymmetry. The application of Extreme function enhanced the regression accuracy of parameters and the prediction was in a fairly good agreement with the new experiments. These results promise the wide use of statistical models for the quantitative safety assessment.

• 한국식품저장유통학회지
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• 제7권2호
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• pp.177-183
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• 2000

A supercritical fluid extraction was performed for the extraction of phenolics from grape seeds which up to now have been discarded. The optimum condition for extraction process was predicted through response surface methodology using central composit experimental design. The extraction amount of grape seed phenolics was increased by increasing extraction temperature, pressure, and concentration of co-solvent (ethanol). The optimum extraction conditions were 84.83$^{\circ}$C, 51.50MPa and 1.27% ethanol. The yield of phenolics using SFE was higher with 3 folds than ethanol and 4 folds than hexane but less than 80% methanol. In the respects of food poisoning, the approved solvents were restricted to ethanol and hexane. So, SFE for extraction of phenolics could be powerful alternative method for solvent extraction.

• Journal of Microbiology and Biotechnology
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• 제24권11호
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• pp.1542-1550
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• 2014

Co-digesting molasses wastewater and sewage sludge was evaluated for hydrogen production by response surface methodology (RSM). Batch experiments in accordance with various dilution ratios (40- to 5-fold) and waste mixing composition ratios (100:0, 80:20, 60:40, 40:60, 20:80, and 0:100, on a volume basis) were conducted. Volatile solid (VS) concentration strongly affected the hydrogen production rate and yield compared with the waste mixing ratio. The specific hydrogen production rate was predicted to be optimal when the VS concentration ranged from 10 to 12 g/l at all the mixing ratios of molasses wastewater and sewage sludge. A hydrogen yield of over 50 ml $H_2/gVS_{removed}$ was obtained from mixed waste of 10% sewage sludge and 10 g/l VS (about 10-fold dilution ratio). The optimal chemical oxygen demand/total nitrogen ratio for co-digesting molasses wastewater and sewage sludge was between 250 and 300 with a hydrogen yield above 20 ml $H_2/gVS_{removed}$.

• Journal of Applied Biological Chemistry
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• 제44권1호
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• pp.16-19
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• 2001

Soybean plants(Glycine max [L.] merr.) inoculated with Bradyrhizobium japonicum MN110 were grown in growth chambers under 400 or $800{\mu}l{\cdot}l^{-1}$ atmospheric $CO_2$ and harvested at 25, 28, 32, and 35 DAT to examine the effect of $CO_2$ enrichment on phosphorus accumulation, uptake, and utilization efficiency during vegetative growth. Phosphorus concentration in leaf was lower in high $CO_2$ plant by 47% at 25 DAT and 34% at 35 DAT than those in the control plant but phosphorus concentrations in stem, root and nodule were not affected by $CO_2$ enrichment. Total phosphorus accumulation increased 3.9-fold in high $CO_2$ plant and 3.2-fold in the control plant between 25 and 35 DAT. Elevated $CO_2$ caused a decrease in the whole plant phosphorus concentration by 35%, which was due almost entirely to a decrease in the phosphorus concentration of leaves. $CO_2$ enrichment increased phosphorus utilization efficiency in the whole plant by 70% during the experimental period. Plants exposed to high $CO_2$ had larger root systems than under ambient $CO_2$, but high $CO_2$ plants had lower P-uptake efficiency. Averaged over four harvests, plants at high $CO_2$ had 38% larger root mass that was more than offset the 20% lower efficiency of P-uptake and accounted for increased phosphorus accumulation by high $CO_2$ plant. These results suggest that the reduced phosphorus concentration in soybean plant under $CO_2$ enrichment may be an acclimation response to high $CO_2$ concentration or enhanced starch accumulation, resulting in the plants to have a lower phosphorus requirement on a unit dry weight basis or a high phosphorus utilization efficiency under these conditions.

• Bulletin of the Korean Chemical Society
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• 제35권4호
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• pp.1177-1181
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• 2014

A 2D grid-like (4, 4)-connected topology coordination polymer, $[Co(BTA)_2(H_2O)_2]_n$ (1), where HBTA = 2-(1H-benzotriazol-1-yl)acetic acid, has been synthesized by hydrothermal method and characterized by single crystal X-ray diffraction, IR spectroscopy, elemental analysis and surface photovoltage spectroscopy (SPS). X-ray diffraction analyses indicated that 1 displays octahedral metal centers with secondary building units (SBUs) [$Co(BTA)_2(H_2O)_2$] bridged by the $BTA^-$ ligands. In the crystal, the 2D supramolecular architecture is further supported by $O-H{\cdots}O$, $O-H{\cdots}N$, $C-H{\cdots}O$ hydrogen bonds and ${\pi}{\cdots}{\pi}$ stacking interactions. The SPS of polymer 1 indicates that there are positive response bands in the range of 300-600 nm showing photo-electric conversion properties. There are good relationships between SPS and UV-Vis spectra.

• 한국결정성장학회지
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• 제31권2호
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• pp.78-83
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• 2021

본 연구에서는 수열반응법을 이용하여 3차원 구조를 갖는 NiCo2O4 입자를 합성했다. 수열합성에서 반응조건 [Ni]/[Co] 비율, 반응시간과 열처리온도를 달리하여 입자의 조성과 형상을 조절했다. 최적의 조건을 결정하고자 XRD, SEM을 통해 입자를 분석하였으며, [Ni]/[Co] 1:2 비율, 반응시간 12시간, 열처리 400℃ 4시간 조건에서 3차원 구조를 갖는 단일상의 NiCo2O4가 합성하였다. 합성된 NiCo2O4 나노구조체의 글루코스 센서 특성평가 결과, 글루코스에 대해 높은 민감도와 탁월한 선택성을 나타냈다. 본 연구를 통해 합성한 NiCo2O4 나노구조체는 향후 비효소 기반 전기화학적 글루코스 센서로 널리 응용될 수 있을 것으로 기대된다.

• 한국안전학회지
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• 제3권2호
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• pp.49-53
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• 1988

The perovskite-type compounds $La_{1-x}Ca_xCoO_3$ were synthesized, their thermochemical properties and the gaseous sensitivity were investigated in ethanol vapor. The maximum response for detecting gas corresponded with the exothermic peak of DTA experiment. In any case the substituent was increased, the responsive ratio for detecting gas was grown upon. However, the needed time for response was later, and the operating temperature was elevated. The mechanism of this electrical conductivity was explained by the oxygen ionic diffusion through oxygen vacancy produced by the substituent.

• 공업화학
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• 제34권2호
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• pp.111-120
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• 2023

이산화탄소 순환 물질 중 대표적인 광물인 탄산칼슘의 형성 과정을 관찰하고, 대표적 조절 변수인 마그네슘-칼슘 이온의 혼합 비율(Mg/Ca 비)과 온도가 pre-nucleation cluster (PNC) 및 탄산칼슘 형성에 미치는 영향을 분석하고자 실험과정에서 칼슘 이온 선택성 전극(calcium ion selective electrode, Ca ISE)을 이용하여 핵형성 과정을 연구하였다. 실험결과 미량의 결정이 형성되었으며 표면 원소 분석을 위해 에너지 분산 X선 분석법(energy dispersive X-ray spectroscopy, EDS)을 사용하였고, 형상 분석을 위해 주사 전자 현미경(field emission scanning electron microscope, FE-SEM)을 사용하였다. Mg/Ca 비와 온도 조건에 따라 다양한 형상의 결정질 탄산칼슘(방해석, 아라고나이트 등)을 확인하였으며 Ca ISE로부터 얻은 칼슘 이온 농도 그래프는 탄산칼슘 형성 과정을 보여주었다. 칼슘 이온 농도 그래프 분석을 통해 마그네슘 이온은 칼슘 이온과 탄산 이온의 결합을 방해하고 PNC 간 응집을 지연시켜 핵형성 및 탄산칼슘의 형성을 지연시킴을 확인하였다. 반면 온도는 이와 반대되는 효과를 보였으며, 본 실험 조건에서는 마그네슘 이온보다 더 큰 영향을 미쳤다. 또한 Mg/Ca 비와 온도에 따라 탄산칼슘의 형상이 뚜렷하게 변화하여 두 인자는 탄산칼슘 형성 과정에 전반적으로 영향을 미치는 중요 조절 변수임을 확인하였다.

• 생태와환경
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• 제46권2호
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• pp.234-240
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• 2013

$CO_2$ 농도 증가에 의한 지구온난화는 식물의 생장과 발달에 영향을 미친다. 이에 우리나라의 우점종인 소나무, 가로수로 많이 쓰이는 은행나무 그리고 난대림의 우점종인 종가시나무와 멸종위기 식물로 지정된 개가시나무, 미선나무의 유식물을 대상으로 $CO_2$ 농도와 온도증가를 증가시킨 지구온난화 처리구와 대조구로 나누어 실험을 하였다. 2010년 4월부터 2011년 11월까지 지상부 길이와 잎 수를 측정하였다. 그 결과 소나무, 은행나무 그리고 종가시나무의 지상부 생장량은 대조구와 지구온난화 처리구에서 차이가 없었다. 개가시나무와 미선나무의 지상부생장량은 대조구보다 처리구에서 높았으나, 잎 수는 $CO_2$ 농도와 온도증가에 의해 영향을 받지 않았다. 이상으로 볼 때, 지구온난화 조건이 되면 우점하고 있는 소나무, 은행나무, 종가시나무보다 멸종위기식물인 미선나무와 개가시나무의 지상부 생장에 유리할 것이다.

• Preventive Nutrition and Food Science
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• 제4권1호
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• pp.79-83
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• 1999

A potentiometric biosensor employing a CO3-2 ion-selective electrode(ISE) and malic enzyme immobilization in al flow injection analysis (FIA) system was constructed. Analytical parameters were optimized for L-malate determination . The CO3-2 -ISE-FIA system was composed of a pump, an injector, a malic enzyme (EC1.1.1.40) reactor, a CO3-2 ion-selective electrode, a pH/mV meter and a recorder. Cofactor NADP was also injected with substrate for theenzyme reaction into the system. Optimized analytical parameters for L-malate determination in the CO3-2 ISE-FIA system were as follows ; flow rate, 14.5ml/hr ; sample injection volume, 100ul; enzyme loading in the reactor, 20 units ; length of the enzyme reactor , 7 cm ; tubing length form the enzyme reactor to the detector as a geometric factor in FIA, 15 cm . The response time for measuring the entire L-malate concentration range (10-2 ~10-5 mol/L ; 4 injections )was <15minutes . In this CO3-2 -ISE-FIA system, the potential differences due to th eformation of CO3-2 by the reaction of malic enzyme on L-malate were correlated to L-malate concentration in the range of 10-2 ~10-5mol/L ; the detection limit was 10-5 mol/L. This potentionmetric CO3-2 ISE--FIA system was found to be useful for L-malate measurement.