• 한국미생물·생명공학회지
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• 제22권6호
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• pp.651-658
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• 1994

For the production of digoxin by using biotransformation in suspension-cultured Digita- lis lanata cells, a two-stage culture process was optimized. Modified Murashige and Skoog medium was used for growth in the first stage and the cells were transferred to glucose solution for the production of digoxin from digitoxin via biotransformation in the second stage. When the cells were cultivated for 10 days in the growth period, 12$\beta$-hydroxylation capacity was the best. It was found that the optimum amount of digitoxin as substrate was 400 mg/l with initial cell density of 21%. Maximum productivity was achieved 5 days after transfer of cells to production medium. Sucrose and fructose provided similar digoxin yield as that in glucose, and 6% was proved to be the best glucose solution. Most of the components of modified MS medium except phosphate reduced the efficiency of digoxin formation. Besides, peptone and beef extracts inhibited 12$\beta$-hydroxylation, while promoting glucosylation. Finally, it was apparent that light enhanced the formation of digoxin significantly.

• KSBB Journal
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• 제16권4호
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• pp.356-359
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• 2001

톨루엔을 분해하는 대표적인 미생물로 알려진 Pseudomonas putida를 이용하여 생분해 특성을 살펴보고자 하였다. 톨루엔은 물에 대한 용해도가 매우 낮기 때문에, 호기적 조건으로 배양하는데 어려움이 있다. 톨루엔을 포함하는 배지를 포함한 닫힌 계를 이용함으로써, 반응기 내에서의 톨루엔 분해와 미생물 성장에 관해 살펴보았다. 초기에 액상으로 접종하는 톨루엔의 농도를 변화시켰고, 이에 따른 headspace에서의 톨루엔의 농도와 미생물 균체 농도 변화를 측정하였다. 닫힌계에서의 톨루엔 생분해에 관한 물질 수지식을 세우고 이를 전산 모사함으로써, 실험 값과 비교 분석하였다. Pseudomonas putida의 resting cell을 이용하면 닫힌 계에서도 톨루엔을 분해할 수 있었고, 반응기 내에서 일어나는 현상을 매개 변수를 통해 고찰하였다.

• 한국전기화학회:학술대회논문집
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• 한국전기화학회 2000년도 전지기술심포지움
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• pp.51-62
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• 2000

Large plastic Li-ion (PLI) cells (25 to 28-Ah) were fabricated for an EV application. The 28-Ah cells showed high specific energy (160 Wh/kg), high specific power (526 W/g), excellent round-trip energy efficiency $(92\%)$, and low self-discharge rate ($6\%$ in 30 days). A 25-Ah cell of an earlier design showed good cycle life of up to 750 cycles at $100\%$ DOD to $80\%$ of its initial capacity, while cycle life test of a 28-Ah cell of a later design is in progress. Preliminary safety tests were also carried out using 6-Ah cells of a similar electrode design giving very encouraging results for development of a safe hish-energy density PLI battery for EV application.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• 제22권6호
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• pp.571-575
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• 2019

We report a case of a 13-year-old girl who presented with a 2-month history of intermittent abdominal pain. Laboratory examination showed hepatitis and pancreatitis. Because of persistent vomiting, computed tomography (CT) was performed, which revealed a circumferential soft tissue density in the duodenal wall, causing partial obstruction. Supportive therapy failed. Repeat CT showed no significant change from the initial study. The patient underwent upper endoscopy, which revealed a mass in the second portion of the duodenum, which occluded most parts of the lumen. The histopathological finding was consistent with an anaplastic large cell lymphoma, a rare form of small bowel neoplasm. After the third course of chemotherapy, complete resolution of the mass was noted, and her symptoms were relieved.

• KSBB Journal
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• 제9권3호
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• pp.253-265
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• 1994

혈청의 종류에 따른 하이브라도마 2c3.1세포의 성 장과 간염 표면 항원에 대한 단얼클론항체 생산에 미치는 영향을 조사하였다. 혈청은 fetal bovine s sera, newborn bovine calf sera, including supple m mented calf sera, horse serum, goat serum의 종류 를 사용하였다. 혈 청농도를 0.5%, 1.25%, 2.5%, 5%(v/v)로 변화시키고, 초기 세포농도를 $5{\times}10^4, 1{\times}10^5, 2{\times}10^5,$ cells/ml로 변화하여 현탁배양한 후 각각의 배지에서 하이브리도마 세포성장과 생산된 단일클론항체의 최대값을 비교하였다. 초기 세포농도를 $1{\times}10^5,$ cells/mlcells/ml로 일정하게 유지하였을 때 세포성장은 혈청의 종류에 관계없이 혈청농도의 증가와 밀접한 관련이 있었고, 혈청농도의 증가에 따른 서l포성장 증가로 인하여 항체 생산도 또한 증가되였 다. 5%의 혈청농도에셔 세포성장과 항체 생산은 초기 세포농도의 증가함에 따라 증가하였다. 같은 종 류의 혈청이라도 혈청 제조사에 따라 세포성장과 항 체 생산에 따른 영향을 끼침을 알았다. 이들 결과로 부터 하이브라도마 세포성장과 항체 생산을 증가하고 세포배양 비용을 줄일 수 있는 혈청의 종류와 농도를 결정하였다.

• Membrane and Water Treatment
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• 제7권2호
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• pp.127-141
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• 2016

Electrodialysis (ED) is known to be a useful membrane process for desalination, concentration, separation, and purification in many fields. In this process, it is desirable to work at high current density in order to achieve fast desalination with the lowest possible effective membrane area. In practice, however, operating currents are restricted by the occurrence of concentration polarization phenomena. Many studies showed the occurrence of a limiting current density (LCD). The limiting current density in the electrodialysis process is an important parameter which determines the electrical resistance and the current utilization. Therefore, its reliable determination is required for designing an efficient electrodialysis plant. The purpose of this study is the development of a predictive model of the limiting current density in an electrodialysis process using response surface methodology (RSM). A two-factor central composite design (CCD) of RSM was used to analyze the effect of operation conditions (the initial salt concentration (C) and the linear flow velocity of solution to be treated (u)) on the limiting current density and to establish a regression model. All experiments were carried out on synthetic brackish water solutions using a laboratory scale electrodialysis cell. The limiting current density for each experiment was determined using the Cowan-Brown method. A suitable regression model for predicting LCD within the ranges of variables used was developed based on experimental results. The proposed mathematical quadratic model was simple. Its quality was evaluated by regression analysis and by the Analysis Of Variance, popularly known as the ANOVA.

• Steel and Composite Structures
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• 제51권1호
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• pp.53-61
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• 2024

Aluminum foams sandwich panel (AFSP) has been used in engineering field, where cyclic loading is used in most of the applications. In this paper, the fatigue life of AFSP prepared by the bonding method was investigated through a three-point bending test. The mathematical statistics method was used to analyze the influence of different plate thicknesses and core densities on the bending fatigue life. The macroscopic fatigue failure modes and damage mechanisms were observed by scanning electron microscopy (SEM). The results indicate that panel thickness and core layer density have a significant influence on the bending fatigue life of AFSP and their dispersion. The damage mechanism of fatigue failure to cells in aluminum foam is that the initial fatigue crack begins the cell wall, the thinnest position of the cell wall or the intersection of the cell wall and the cell ridge, where stress concentrations are more likely to occur. The fatigue failure of aluminum foam core usually starts from the semi-closed unit of the lower layer, and the fatigue crack propagates layer by layer along the direction of the maximum shear stress. The results can provide a reference for the practical engineering design and application of AFSP.

• 센서학회지
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• 제17권3호
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• pp.195-202
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• 2008

A biosensor based on the measurement of capacitance changes has been designed and fabricated for simple and realtime detection of bacteria. Compared to an impedance measurement technique, the capacitance measurement can make additional measurement circuits simpler, which improves a compatability for integration between the sensor and circuit. The fabricated sensor was characterized by detecting Escherichia coli(E. coli). The capacitance changes measured by the sensor were proportional to E. coli cell density, and the proposed sensor could detect $1{\times}10^6$ cfu/ml E. coli at least. The real-time detection was verified by measuring the capacitance every 20 minutes. After 7 hours of E. coli growth experiment, the capacitance of the sensor in the micro volume well with $4.5{\times}10^5$ cfu/ml of initial E. coli density increased by 20 pF, and that in another wells with $1.5{\times}10^6$ cfu/ml and $8.5{\times}10^7$ cfu/ml initial E. coli density increased by 56 pF and 71 pF, respectively. The proposed sensor has a possibility of the real-time detection for bacterial growth, and can detect E. coli cells with $1.8{\times}10^5$ cfu in nutrient broth in 5 hours.

• Bulletin of the Korean Chemical Society
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• 제30권4호
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• pp.817-820
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• 2009

To meet the high current load requirement from the high energy density realized by metal oxide and high power density graphite, we propose a novel hybrid supercapacitor consisting of Nb2O5 and KS6 graphite in 1.0 M LiPF6-EC:DEC (1:2). This new system exhibits a sloping voltage profile from 2.7 to 3.5 V during charging and presents a high operating voltage plateau between 1.5 and 3.5 V during discharging. The cell was tested at a current density of 100 mA/g with a cut-off voltage between 3.0 and 1.0 V. This novel energy storage system delivers the highest initial discharge capacity of 55 mAh/g and exhibits a good cycle performance.

• Journal of Plant Biotechnology
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• 제4권3호
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• pp.109-115
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• 2002

Submerged cultures of Ganoderma lucidum, a valuable mushroom in traditional Chinese medicine, were used for production of bioactive Banoderic acids and Ganoderma polysaccharides. The significant effects of oxygen supply were demonstrated in both shake flasks and bioreactors. By changing the medium loading volume in a shake flask, a different value of initial volumetric oxygen transfer coefficient ($K_L$a) was obtained, and a higher $K_L$a value led to a higher biomass density and a higher productivity of both intracellular polysaccharide and ganoderic acid. In a stirred bioreactor, at an initial $K_L$a of 78.2 $h^{-1}$, a maximal cell concentration of 15.6 g/L by dry weight was obtained, as well as a maximal intracellular polysarcharide (IPS) production of 2.2 g/L and its maximal productivity of 220 mg/(L.d). An increase of initial $K_L$a led to a higher production and productivity of GA, and the GA production and productivity at an initial $K_L$a of 96.0 $h^{-1}$ was 1.8-fold those at an initial $K_L$a of 16.4 $h^{-1}$. The fundamental information obtained in this study may be useful for efficient large-scale production of these valuable bioactive products by the submerged cultures.