• 미생물학회지
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• 제14권1호
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• pp.17-24
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• 1976

Celluloytic microorgnasims were isolated form the various sources and four of them were identified as Trichoderma roningi, Aspergillus niger, Penicillium chrysogenum, and Streptomyces sp. The induction of extracellular5 cellulase of these species in the liquid culture media containing carboxymethylcellulose (CMC) or Avicel as inducer showed that CMC was a better effective inducer for the production of CMCase(Cx cellulase component) as well as Avicelase(C$_{1}$ cellulase component) than Avicel. It is believed that certain hydrolysis products of cellulose(CMC) could serve as an inducer for an enzyme synthesis. In T. roningi, Asp. niger, and Strptomyces sp., the optimum temperature of CNCase on CMC-culture medium was 50.deg. but temperature around 40.deg.C was found to be optimum for the activities of CMCase prepared from P.ehrysogenum. The optimum temperature for Avicelase activitiles on Avicel-culture media of T. roningi and P. chrysogenum was $40{\circ}C$ whereas temperature $50{\circ}C$ was found to be optimum for Avicelase from A.niger and Streptomyces sp. The optimal activities of these CNCase and Avicelase prepared from. T. ronigi, Pen.chrysogenum and Streptomyces sp. were found similarly to be at pH's around 5.4 and 6.0 while pH 4.8 was optimum for the activities of CMCase and Avicelase from A.niger, indicating that A.niger in acidic media would yield an enzyme of high activity.

• 한국산림과학회지
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• 제73권1호
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• pp.33-42
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• 1986

현사시 (Populus alla${\times}$P. glandulosa)의 기내배양(器內培養) 엽육조직(葉肉組織)으로부터 원형질체(原形質體)의 분리(分離) 및 배양(培養)을 시험하였다. 무균(無菌)의 엽육조직(葉肉組織)을 육성(育成)하기 위한 shoot의 대량증식에는 MS기본배지에 BAP 0.4 mg/l을 첨가하였을 때 가장 증식효과가 높았으며, 원형질체(原形質體)의 분리(分離)를 위한 효소농도는 Cellulase 2%, Macerozyme 0.8%, Hemicellulase 1.2%, Driselase 2%, Pectolyase Y-23 0.05%가 가장 효과적이었다. 효소용액의 삼투압은 mannitol 0.6 M이 적합하였으며, pH는 5.6이 적절하였다. 원형질체(原形質體)의 안정성을 높이기 위하여 DTT와 MES buffer를 첨가하여 좋은 결과를 얻었다. 분리(分離)된 원형질체(原形質體)의 정제를 위해서는 부유용액(浮遊溶液)의 sucrose 농도를 0.6M로 하였을 때가 가장 적합하였으며 dextran의 첨가효과도 높았다. 본 연구의 특징은 다소 높은 농도의 효소용액을 처리하여 단시간에 원형질체(原形質體)를 분리(分離)하는 것으로서 이 방법에 의해 나출(裸出)된 원형질체(原形質體)의 배양(培養)에 있어서 반응여부를 조사한 결괴 배양 3주 후에까지도 좋은 반응을 보였다.

• Journal of Microbiology and Biotechnology
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• 제24권8호
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• pp.1034-1043
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• 2014

This study determined the effect of light intensity and photoperiod on the dry cell weight and total amount of carotenoids in four isolates of purple non-sulfur bacteria obtained from shaded and exposed microhabitats of a mangrove ecosystem in Kota Kinabalu, Sabah, Malaysia. The initial isolation of the bacteria was carried out using synthetic 112 medium under anaerobic conditions (2.5 klx) at $30{\pm}2^{\circ}C$. On the basis of colony appearance, cell morphology, gram staining, motility test, and 16S rRNA gene sequencing analyses, all four bacteria were identified as Afifella marina. One of the bacterial isolates, designated as Af. marina strain ME, which was extracted from an exposed mud habitat within the mangrove ecosystem, showed the highest yield in dry cell weight ($4.32{\pm}0.03g/l$) as well as total carotenoids ($0.783{\pm}0.002mg/g$ dry cell weight). These values were significantly higher than those for dry cell weight ($3.77{\pm}0.02g/l$) and total carotenoid content ($0.706{\pm}0.008mg/g$) produced by the isolates from shaded habitats. Further analysis of the effect of 10 levels of light intensity on the growth characteristics of Af. marina strain ME showed that the optimum production of dry cell weight and total carotenoids was achieved at different light intensities and incubation periods. The bacterium produced the highest dry cell weight of 4.98 g/l at 3 klx in 72 h incubation, but the carotenoid production of 0.783 mg/g was achieved at 2.5 klx in 48 h incubation. Subsequent analysis of the effect of photoperiod on the production of dry cell weight and total carotenoids at optimum light intensities (3 and 2.5 klx, respectively) revealed that 18 and 24 h were the optimum photoperiods for the production of dry cell weight and total carotenoids, respectively. The unique growth characteristics of the Af. marina strain ME can be exploited for biotechnology applications.

• Asian-Australasian Journal of Animal Sciences
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• 제32권2호
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• pp.241-248
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• 2019

Objective: To isolate and identify new methanogens from the rumen of Holstein steers in Korea. Methods: Representative rumen contents were obtained from three ruminally cannulated Holstein steers ($793{\pm}8kg$). Pre-reduced media were used for the growth and isolation of methanogens. Optimum growth temperature, pH, and sodium chloride (NaCl) concentration as well as substrate utilization and antibiotic tolerance were investigated to determine the physiological characteristics of the isolated strain. Furthermore, the isolate was microscopically studied for its morphology. Polymerase chain reaction of 16S rRNA and mcrA gene-based amplicons was used for identification. Results: One strain designated as KOR-2 was isolated and found to be a non-motile irregular coccus with a diameter of 0.2 to $0.5{\mu}m$. KOR-2 utilized $H_2+CO_2$ and formate but was unable to metabolize acetate, methanol, trimethylamine, 2-propanol, and isobutanol for growth and methane production. The optimum temperature and pH for the growth of KOR-2 were $38^{\circ}C$ and 6.8 to 7.0, respectively, while the optimum NaCl concentration essential for KOR-2 growth was 1.0% (w/v). KOR-2 tolerated ampicillin, penicillin G, kanamycin, spectromycin, and tetracycline. In contrast, the cell growth was inhibited by chloramphenicol. Phylogenetic analysis of 16S rRNA and mcrA genes revealed the relatedness between KOR-2 and Methanoculleus bourgensis. Conclusion: Based on the physiological and phylogenetic characteristics, KOR-2 was thought to be a new strain within the genus Methanoculleus and named Methanoculleus bourgensis KOR-2.

• Structural Engineering and Mechanics
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• 제75권1호
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• pp.33-47
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• 2020

In this paper the dynamic behavior of an isolated building subjected to idealized near-fault pulses is investigated. The building is represented with a simple 2-DOF model. Both linear and non-linear behavior of the isolation system is considered. Using dimensional analysis, in conjunction with closed form mathematical idealized pulses, appropriate dimensionless parameters are defined and self-similar curves are plotted on dimensionless graphs, based on which various conclusions are reached. In the linear case, the role of viscous damping is examined in detail and the existence of an optimum value of damping along with its significant variation with the number of half-cycles is shown. In the nonlinear case, where the behavior of the building depends on the amplitude of the excitation, the benefits of dimensional analysis are evident since the influence of the dimensionless 𝚷-terms is easily examined. Special consideration is given to the normalized strength of the non-linear isolation system that appears to play a complex role which greatly affects the response of the 2-DOF. In the last part of the paper, a comparison of the responses to idealized pulses between a linear fixed-base SDOF and the respective isolated 2-DOF with both linear and non-linear damping is conducted and it is shown that, under certain values of the superstructure and isolation system characteristics, the use of an isolation system can amplify both the normalized acceleration and displacement of the superstructure.

• 전력전자학회논문지
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• 제21권5호
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• pp.434-441
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• 2016

This paper deals with transformer turns ratio design with the consideration of loss minimization in isolated bidirectional DC-DC converter. Generally, the rms value of current, magnitude of current at switching instance, and duty ratio of a converter vary according to the turns ratio of an isolation transformer in the converter under the same voltages and output power level. Therefore, the transformer turns ratio has an effect on the total loss in a converter. The switching and conduction losses of IGBTs and MOSFETs consisting of dual-active bridge converter are analyzed, and iron and copper losses in an isolation transformer and inductor are calculated. Total losses are calculated and measured in cases of four different transformer turns ratios through simulation and experiment with 3-kW converter, and an optimum turns ratio that provides minimum losses is found. The usefulness of the proposed transformer turns ratio design approach is verified through simulation and experimental results.

• 한국정보통신학회논문지
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• 제11권9호
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• pp.1642-1649
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• 2007

본 논문에서는 온도보상 자기회로를 갖는 집중정수형 아이솔레이터를 설계하고 전자계 시뮬레이션을 통한 최적 파라미터를 이용하여 각각 K-PCS, GSM1900, W-CDMA, WiBro 대역의 이동통신 중계기용 아이솔레이터를 제작하였으며 IMD 특성을 평가하였다. 결과로서 K-PCS 대역의 경우에 Insertion loss와 Return loss는 각각 0.2dB 이하, 25dB이상, Isolation 23dB에서 대역폭은 30MHz이었고 GSM1900의 경우에는 각각 0.25dB, 23dB, Isolation 30 dB에서 대역폭은 60 MHz이었으며 W-CDMA의 경우에는 각각 0.15dB, 25dB, Isolation 24.8 dB테서 대역폭은 60 MHz이었다. 또한 WiBro 대역의 경우에는 각각 0.25dB, 23dB 이상, Isolation 22.1dB에서 대역폭은 100MHz이었고 IMD측정 결과는 $76.4dBc{\sim}80.1dBc$이었으며 기존의 제품에 비하여 우수한 특성을 가지고 있음을 확인하였다.

• 한국미생물·생명공학회지
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• 제17권5호
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• pp.429-435
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• 1989

A bacterial strain of Brevibaterium sp. CH1 was isolated and used to produce an enzyme (nitrile hydratase) necessary for earring out the bioconversion of acrylonitrile to acrylamide. The culture and reaction conditions, and medium optimization were studied for the strain. The conversion yield was nearly 100％ with a trace amount of acrylic acid produced. The strain showed strong activity of nitrile hydratase toward acrylonitrile and extremely low activity of the amidase toward acrylamide. We sought optimum culture conditions for the formation of nitrile hydratase by Brevibacterium sp. CH1. The effects of temperature and pH on the activity of free and immobilized tells were investigated. The nitrite hydratase of Brevibacterium sp. CH1 acted not only on various aliphatic nitrites such as acrylonitrile, propionitrile and acetonitrile, but also on aromatic nitrile as nicotinonitrile.

• Journal of Microbiology
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• 제34권4호
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• pp.305-310
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• 1996

A microorganism producing carboxymethyl-cellulase (CMCase) was isolated from 300 soil and compost samples. The isolate was identified as Bacillus sp. by $Biolog^{TM}$ test and fatty acid analysis, and named as Bacillus sp. KD1014. The isolate could degrade, in addition to CMC, various kinds of polysaccharides such as levan, xylan, starch, and filter paper but hardly degrade microcrystalline Avicel. The optimum growth and CMCase production of the isolate was observed between 16-and 25 hr-culture at 45$^{\circ}C$ and pH 5.0. The maximum CMCase activity was observed at pH 4.5 and 6$0^{\circ}C$. The CMCase was found to bind to Avicel. The CMCase was internally cleaved as growth continued. When crude supernatant was used for activity staining, three major bands were detected on a native gel, however, only one major band was detected on a denaturating gel after removal of the detergent.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제51권7호
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• pp.311-315
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• 2002

Chemical mechanical polishing (CMP) process was required for the global planarization of inter-metal dielectric(IMD), inter-level dielectric (ILD) layers of multi-layer interconnections. In this paper, we studied the characteristics of polishing pad, which can apply shallow trench isolation (STI)-CMP process for global planarization of multi-level interconnection structure. Also, we investigated the effects of different sets of polishing pad, such as soft and hard pad. As an experimental result, hard pad showed center-fast type, and soft pad showed edge-fast type. Totally, the defect level has shown little difference, however, the counts of scratch was detected less than 2 on JR111 pad. Through the above results, we can select optimum polishing pad, so we can expect the improvements of throughput and device yield.