• 한국신재생에너지학회:학술대회논문집
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• 2010.11a
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• pp.105.2-105.2
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• 2010

전처리 후 얻어진 셀룰로스 고분자를 단당류로 전환하기 위해서는 셀룰라제를 이용한 당화 과정이 필요하다. 통상 실험식 연구에서는 셀룰로스 당화시 당수율을 최대로 하기위해 pH조절을 위한 Citrate buffer와 미생물 오염을 막기 위한 Autoclave에서의 멸균 과정을 거친다. 하지만 대량생산을 목적으로 하는 산업체에서는 적용이 어렵다는 문제점이 있다. 따라서 본 연구에서 이를 대신하여 산업체에서 적용 가능한 당화전환 공정의 효율성을 평가하고자 하였다. Autoclave 멸균을 대체하는 공정으로 항생제 첨가와 여과에 의한 제균을 선택하였고, citrate buffer를 대신하여 buffer를 첨가하지 않은 물을 pH를 조정하여 사용 하였다.실험결과 기존의 당화공정을 사용하였을 때 당화율이 81%이었고, pH를 조절한 제균 water에 항생제를 첨가하는 공정은 71%로 나머지 배지들 중 가장 높은 당화율을 나타냈다. 이것은 기존의 당화율보다 10% 낮은 수치이나 공정비를 교려하여 봤을 때 효율성 있는 공정으로 판단된다.

• Korean Chemical Engineering Research
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• v.54 no.3
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• pp.404-409
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• 2016

Thermal Characteristics and kinetic parameters of $LaMnO_3$ synthesis reaction were investigated by means of TGA (Thermogravimetric analysis) at non-isothermal heating conditions (5.0, 10.0, 15.0 and 20.0 K/min). The reaction was occurred rapidly at 450~600K (X=0.4~0.7) depending on the heating rate. Activation energy for the synthesis of $LaMnO_3$ from the precursor, which was determined by different method such as Friedman, Ozawa-Flynn-Wall and Vyazovkin methods, was in the range of 23~243 kJ/g-mol depending on the fractional conversion level and estimation method. The reaction order decreased with increasing heating rate and fractional conversional level. The average reaction order was 4.50 in case of X=0.1~0.3, while it was 1.87 in case of X=0.7~0.9, respectively. The value of frequency factor of reaction rate increased with inceasing heating rate and fractional conversion level. The aveage value of frequency factor was 205.6 ($min^{-1}$) when X=0.1~0.3, while it was 475.2 ($min^{-1}$) when X=0.7~0.9, respectively.

• The Transactions of the Korean Institute of Power Electronics
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• v.9 no.3
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• pp.195-202
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• 2004

This paper presents a current control strategy to reduce torque ripple of Brushless DC Motor during con)mutation. The torque ripple is mainly caused by the inequality in the rate of change between rising current and decaying one during commutation. And also it is influenced by the shape of real back EMF Therefore, in the proposed control strategy, considering real back EMF a compensation voltage is generated to equalize the rate of change in these commutating currents. And then, by providing the compensation voltage during commutation, the torque ripple can be reduced. The simulation md experimental results verify that the proposed method can reduce the torque and the current ripples significantly.

• Journal of Industrial Convergence
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• v.18 no.5
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• pp.1-13
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• 2020

The purpose of this study is to find out how much the investment effect of convertible bond(CB) is from the perspective of investors and to present efficient investment plans to investors. The research method is to investigate the coupon interest rate, maturity interest rate, conversion price, etc. for CBs. As a result of the study, it was analyzed that CB's investment efficiency was low because the conversion price excess days ratio was only about 1/4 of the conversion date. The conversion day yield was -6.3% and the maturity day yield was -5.2% on average. It was analyzed that the number of stocks with negative conversion day yield was 2.4 times higher than the number of positive stocks and 3.7 times higher than the number of positive stocks with a maturity day yield, so the expected return on equity conversion of CB was low.

• 한국생물공학회:학술대회논문집
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• 2000.04a
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• pp.474-477
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• 2000

An organic solvent-tolerant Pseudomonas savastanoi strain BCNU 106 was isolated.. This bacterium was gram negative rod, and showed oxidase positive, catalase positive, and decaboxylase positive reactions. The Pseudomonas strain oxidized cholesterol on the medium supplemented with an organic solvent. The strain BCNU 106 is able to grow in presence of organic solvents of which log $P_{ow}$ is between 1.5 to 7.0. The strain was well grown in a medium supplemented with a 10% volume of a organic solvent (toluene, p-xylene, cyclohexane, mesitlylene) containing $cholesterol(20mg/m{\ell)$. Major conversion compound were 7-dehydrocholesteryl dimethylphosphate, cholesta-4,7-dien-3-one, and cholesta-3,5-dieone.

• Journal of Korean Society of Environmental Engineers
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• v.29 no.4
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• pp.444-451
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• 2007

Catalytic oxidation characteristics of benzene as a VOC was investigated using a fixed bed reactor system over transition $metals/\gamma-Al_2O_3$ catalysts. As transition metals, eight metals including copper, nickel, manganese, iron etc. were adopted. The parametric tests were conducted at the reaction temperature range of $200\sim500^{\circ}C$, benzene concentration of $1,000\sim3,000$ ppm, and space velocity range of $5,000\sim60,000\;hr^{-l}$. The property analyses such as BET, SEM, XRD and the conversions of catalytic oxidation of VOC were examined. The experimental results showed that the conversion was increased with decreasing VOC concentration and space velocity. It was also found that $Cu/\gamma-Al_2O_3$ catalyst calcinated at $500^{\circ}C$ showed the highest activity for the oxidation of benzene and 15% metal loading was the optimum impregnation level.

• Proceedings of the Korean System Dynamics Society
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• 2000.07a
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• pp.135-152
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• 2000

지배적 피드백 루프는 구조가 시스템의 행동을 유발한다는 점에 있어서 매우 중요한 개념이다. 본 논문에서는 지배적 피드백 루프의 전환을 완만한 전환(continuous shifts)과 급격한 전환(discrete shifts)의 두 가지로 분류하였다. 본 연구에서는 지배적 피드백 루프의 전환에 대한 인지적 편향을 세 가지의 가설로 분류하여 제시하였다. 이에는 1) 완만한 전환에 대한 인식의 실패, 2) 의사결정 자들의 급격한 전환에 의존하는 경향, 3) 지배적 피드백 루프의 인식에 있어서 수준변수와 변화율 변수간의 차이 등이 포함된다. 마지막으로 본 논문에서는 지배적 피드백 루프에 의한 인지적 편향이 의사결정과정의 시간지연과 정책 개입의 시기에 대하여 어떠한 시사점을 주는지에 관하여 논의하였다.

• 한국신재생에너지학회:학술대회논문집
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• 2011.11a
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• pp.109.2-109.2
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• 2011

바이오디젤의 생산은 원료유의 순도와 촉매 종류, 알코올의 양, 반응시간, 반응 온도와 같은 다양한 조건을 이용하여 최적의 조건을 찾아내는 것이 중요하며 이는 곧 생산단가와 직결된다. 바이오디젤 전환 시 고체촉매를 이용하면 후처리 공정의 단순화가 가능하며 글리세린의 순도가 약 98%로 매우 높아져 고부가 물질 생산 원료로 활용이 가능하다는 장점이 있으며 생산 단가를 4~20% 가량 낮출 수 있다. 본 연구에서는 바이오디젤의 경제적인 생산을 위하여 정제공정을 단순화 시킬 수 있는 방안으로 3종의 고체촉매를 이용하여 동 식물성 유지의 바이오디젤로 전환 실험을 수행 하였다. 촉매 활성화를 위하여 고체촉매를 $700^{\circ}C$에서 3~5시간 소성하고 동 식물성 유지를 이용 전이에스테르화 반응실험을 수행하여 30분 간격으로 시료를 수집 하였다. 실험 결과, 동물성 폐유지로부터 반응 120분 후에 최대 90% 이상의 지방산 메틸에스테르로의 전환율을 얻을 수 있었으며 식물성 유지인 팜유에서는 86%, 유채유에서는 64%의 전환율을 나타냈다. 동 식물성 유지의 초기 산가는 0.45~2mg KOH/g 사이로 나타났다.

• Horticultural Science & Technology
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• v.18 no.6
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• pp.797-801
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• 2000

The present study was conducted to improve the efficiency of transformation mediated by Agrobacterium tumefaciens in hot pepper. Both regeneration ratio and transformation frequency after the cocultivation with A. tumefaciens were affected by inoculation time and artificial wounding. Transformation frequency was increased over 50% by combining artificial wounding with 120 s of inoculation treatment. Confirmation for the transformation of regenerated shoots was carried out by histochemical ${\beta}$-glucuronidase assay and polymerase chain reaction analysis using npt II primer.

• The Korean Journal of Mycology
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• v.11 no.3
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• pp.115-119
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• 1983

The bioconversion of progesterone by Aspergillus phoenicis has been studied. The metabolism in the conditions of experiment gave $11{\alpha}-hydroxyprogesterone$ as main product. The concentration of $11{\alpha}-hydroxyprogesterone$ increased monotonically and leveled off after 40 hours of incubation. Addition of glucose into the medium reduced considerably the time for attaining limiting concentration of $11{\alpha}-hydroxyprogesterone$. The increase in initial progesterone concentration did not affected the percentage of conversion nor the time required for termination of the reaction. But it could not be represented as first order reaction with respect to progesterone concentration. The degree of inhibition of enzymes by organic solvents depended upon the concentration of solvents. At low solvent concentration, acetone proved to yield the highest conversion.