• 한국정밀공학회지
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• 제16권2호통권95호
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• pp.201-210
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• 1999

One of the major limitations of productivity and quality in metal cutting is the machining accuracy of machine tools. The machining accuracy is affected by geometric and thermal errors of the machine tools. Therefore, a key requirement for improving te machining accuracy and product quality is to reduce the geometric and thermal errors of machine tools. This study models geometric error for error analysis and develops on-machine measurement system by which the volumetric erors are measured. The geometric error is modeled using form shaping function(FSF) which is defined as the mathematical relationship between form shaping motion of machine tool and machined surface. The constant terms included in the error model are found from the measurement results of on-machine measurement system. The developed on-machine measurement system consists of the spherical ball artifact (SBA), the touch probe unit with a star type stylus, the thermal data logger and the personal computer. Experiments, performed with the developed measurement system, show that the system provides a high measuring accuracy, with repeatability of ${\pm}2{\mu}m$ in X, Y and Z directions.

• Journal of Microbiology and Biotechnology
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• 제21권4호
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• pp.430-437
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• 2011

The effects of the agitation and aeration rates on the production of serratiopeptidase (SRP) in a 5-L fermentor (working volume 2-l) were systematically investigated using Serratia marcescens NRRL B-23112. The dissolved oxygen concentration, pH, biomass, SRP yield, and maltose utilization were all continuously measured during the course of the fermentation runs. The efficiencies of the aeration and agitation were evaluated based on the volumetric mass transfer coefficient ($K_La$). The maximum SRP production of 11,580 EU/ml with a specific SRP productivity of 78.8 EU/g/h was obtained with an agitation of 400 rpm and aeration of 0.075 vvm, which was 58% higher than the shake-flask level. The $K_La$ for the fermentation system supporting the maximum production (400 rpm, 0.075 vvm) was 11.3 $h^{-1}$. Under these fermentor optimized conditions, kinetic modeling was performed to understand the detailed course of the fermentation process. The resulting logistic and Luedeking-Piret models provided an effective description of the SRP fermentation, where the correlation coefficients for cell growth, SRP formation, and substrate consumption were 0.99, 0.94, and 0.84, respectively, revealing a good agreement between the model-predicted and experimental results. The kinetic analysis of the batch fermentation process for the production of SRP demonstrated the SRP production to be mixed growth associated.

• Journal of Microbiology and Biotechnology
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• 제17권10호
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• pp.1638-1644
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• 2007

The effect of carbon sources on tacrolimus production by a mutant strain of Streptomyces clavuligerus CKD 1119, an isolate from soil, was examined. Among the carbohydrates and oils tested in this work, a mixed carbon source of soluble starch and com oil was the best. An analysis of the culture kinetics also showed that, in contrast to the carbohydrates, the com oil was consumed later in the antibiotic production phase, implying that the oil substrate was the principal carbon source for the biosynthesis of tacrolimus, and this was directly proven by experiments using $^{14}C$-glucose and $^{14}C$-oleate substrates. Furthermore, com oil induced the formation of lipase by the mutant strain, whereas the addition of glucose significantly repressed lipase activity. The lipase activity exhibited by the FK-506-overproducing mutants was also observed to be directly proportional to their tacrolimus yield, indicating that a high lipase activity is itself a crucial factor for tacrolimus production. A feasibility study with a 200-1 pilot-scale fermentor and the best strain (Tc-XII-15322) identified in this work revealed a high volumetric and specific productivity of about 495 mg/l and 0.34 mg/mg dry mycelium, respectively.

• Biotechnology and Bioprocess Engineering:BBE
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• 제2권2호
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• pp.90-93
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• 1997

Recombinant exoinulinase was partially purified form the culture supernatant of S.cerevisiae by(NH4)2SO4 precipitation and PEG treatment. The purfied inulinase was immobilized onto Amino-cellulofine with glutaraldeyde as a cross-linking agent. Immobilization yield based on the enzyme activity was about 15%. Optimal pH and temperature of immobilized enzyme were found to be 5.0 and 6$0^{\circ}C$, respectively. The enzyme activity was stably maintained in the pH ranges of 4.5 to 6.0 at 6$0^{\circ}C$. 100% of enzyme activity was observed even after incubation for 24 hr at 6$0^{\circ}C$. In the operation of a packed-bed reactor containing 412U inulinase, dahalia inulin of 7.5%(w/w) concentration was completely hydrolyzed at flow rate of 2.0mL/min at 6$0^{\circ}C$, resulting in a volumetric productivity of 693 g-reducing sugars/L/h. Under the reaction conditions of 1.0mL/min flow rate with 2.5% inulin at 6$0^{\circ}C$, the reactor was successfully operated over 30 days without loss ofinulinase activity.

• 한국정밀공학회지
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• 제17권1호
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• pp.120-128
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• 2000

One of the major limitations of productivity and quality in metal cutting is the machining accuracy of machine tools. The machining accuracy is affected by geometric errors, thermally-induced errors, and the deterioration of the machine tools. Geometric and thermal errors of machine tools should be measured and compensated to manufacture high quality products. In metal cutting, the machining accuracy is more affected by thermal errors than by geometric errors. This paper models of the thermal errors for error analysis and develops on-the-machine measurement system by which the volumetric error are measured and compensated. The thermal error is modeled by means of angularity errors of a column and thermal drift error of the spindle unit which are measured by the touch probe unit with a star type styluses and a designed spherical ball artifact (SBA). Experiments, performed with the developed measurement system, show that the system provides a high measuring accuracy, with repeatability of $\pm$2${\mu}{\textrm}{m}$ in X, Y and Z directions. It is believed that the developed measurement system can be also applied to the machine tools with CNC controller. In addition, machining accuracy and product quality can be improved by using the developed measurement system when the spherical ball artifact is mounted on the modular fixture.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2000년도 춘계학술발표대회
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• pp.53-56
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• 2000

효모를 이용하여 높은 생산성으로 고농도의 erythritol을 생산하기 위하여 ‘세포 성장단계’와 ‘erythritol 생성단계’로 나누어 2 단계 유가식 배양을 수행하였다. 세포 성장 단계에서는 pH-stat 유가식 배양을 수행하여 3.62 g/L-H의 생산성으로 76 g/L의 균체 농도를 얻을 수 있었다. pH-stat 유가식 배양을 수행하여 고농도의 균체 농도를 얻은 후에 멸균되지 않은 분말형태의 glucose를 발효조에 400 g/L가 되도록 공급하여 세포에 osmotic stress를 가해준 결과 41%의 수율로 187 g/L의 erythritol을 생산할 수 있었으며, 이때의 생산성은 2.79 g/L-h로서 기존에 보고된 어느 결과보다도 높은 값을 얻을 수 있었다. Production phase에서 erythritol 생산에 대한 삼투압의 영향을 알아 본 결과 glucose의 농도가 증가할 수록 생성되는 erythritol 농도가 증가하였으며 세포 농도에 따른 erythritol 생산 수율은 큰 차이는 없었으나 세포 농도가 증가할수록 이에 비례하여 erythritol 생산성이 크게 증가하였다. Erythritol 생산에서 용존 산소량에 관계없이 butyric acid가 생성되었으며 40%의 DO 미만에서는 citric acid가 생성되고, 40% 이상의 DO에서는 gluconic acid가 생성되어 용존 산소량에 의하여 metabolic shift가 유도되었다. 고 농도의 glucose 첨가 후 용존 산소량을 20%로 조절하면서 pH를 3.0으로 낮춘 결과 citrate synthetase의 활성이 억제되어 citric acid가 생성되지 않았으며 gluconic acid 농도는 $KH_2PO_4$에 의하여 증가하고 $MgSO_4{\cdot}7H_2O$ 또는 $(NH_4)_2SO_4$에 의하여 감소되었다. Butyric acid 농도는 $KH_2PO_4$ 또는 $(NH_4)_2SO_4$에 의하여 감소되었으며 synergic effect에 의하여 억제되었다

• Journal of Biosystems Engineering
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• 제36권4호
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• pp.279-284
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• 2011

Protected vegetable production area is greater than 26% of the total vegetable production area in Korea, and portion of protected production area is increasing for flowers and fruits. To secure stable productivity and profitability, continuous and intensive monitoring and control of protected crop production environment is critical, which is labor- and time-consuming. Failure to maintain proper environmental conditions (e.g., light, temperature, humidity) leads to significant damage to crop growth and quality, therefore farmers should visit or be present close to the production area. To overcome these problems, application of remote monitoring and control of crop production environment has been increasing. Wireless monitoring and control systems have used CDMA, internet, and smart phone communications. Levels of technology adoption are different for farmers' needs for their cropping systems. In this paper, potential of wireless remote monitoring of protected agricultural environment using CDMA SMS text messages was reported. Monitoring variables were outside weather (precipitation, wind direction and velocity, temperature, and humidity), inside ambient condition (temperature, humidity, $CO_2$ level, and light intensity), irrigation status (irrigation flow rate and pressure), and soil condition (volumetric water content and matric potential). Scenarios and data formats for environment monitoring were devised, tested, and compared. Results of this study would provide useful information for adoption of wireless remote monitoring techniques by farmers.

• Journal of Biosystems Engineering
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• 제43권2호
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• pp.119-127
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• 2018

Purpose: Fermented feedstuffs have been found to improve productivity, reduce manure odor, and increase immunity. However, because there is not a commercialized pelletizing system for fermented total mixed ration (TMR) for pig feeding in Korea, a pelletizing system using TMR fermented feed was developed. Methods: The particle size, density, and volumetric density of the TMR feeds used in the test were measured. The pellet durability index (PDI, %) value of the pelletized TMR feed based on its moisture content, and the amount of pellet production based on the rotation speed of the compression roller were measured. Results: The test materials, TMR1 and TMR2, were approximately compressed to 387 kg/m3 with 18.2% (w.b.) and 544 kg/m3 with 22.2% (w.b.), respectively. Throughout this pellet molding test, the moisture content from 15 to 20% (w.b.) of mixture feedstuffs, including fermented forage, could be used for pellet molding. Based on the results, a small-scale pellet molding system of fermented TMR was designed and manufactured for pig farms. As rotation speed increased, the throughput increased, whereas the moisture content decreased by approximately 2% (w.b.) because of pellet molding. The best yield of pellets with 94.2% PDI was of 536 kg/h at 135 rpm rotation speed. Conclusions: Although the throughput of the prototype increased as the rotation speed increased, it was difficult to operate because of the greater noise and the lower PDI (%) at the higher rotation speed of the pellet molding rotor. It was found that the best production of pellets using the prototype was 536 kg/h having a PDI of 94.2% or more at a rotation speed of 135 rpm.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2000년도 추계학술발표대회 및 bio-venture fair
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• pp.425-428
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• 2000

본 연구에서는 재조합단백질 생산을 위한 식물세포배양용 세포배양기 운전에서 배지교환식 배양과 기체조성에 따른 영향을 관찰하였다. 배지교환식 배양에서는 6일째에 배지교환을 시작하는 것이 세포의 생장을 저해하지 않았으며 교환용 배지의 조성을 120 g/L sucrose와 2배 농축된 염농도를 하였을 때 가장 높은 세포농도인 20.0 gDCW/L를 나타내었으며 GUS 생산량은 60 g/L sucrose와 기본배지와 같은 농도의 염농도로 배지를 교환했을 때 12.9 U/mL로 다른 경우에 비하여 $1.5^{\sim}4.6$ 배 증가된 결과를 보였다. 그리고 $CO_2$의 농도를 5%로 높인 공기로 통기했을 때는 세포의 초기생장을 증진시켰으며 0.2 vvm의 통기량에서 5% $CO_2$로 통기시킨 경우는 일반 공기를 0.1 vvm으로 통기시킨 경우보다도 77% 높은 GUS의 생산량을 나타내었다.

• Biotechnology and Bioprocess Engineering:BBE
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• 제10권6호
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• pp.522-527
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• 2005

Various processes which produce L-lactic acid using ammonia-tolerant mutant strain, Rhizopus sp. MK-96-1196, in a 3L airlift bioreactor were evaluated. When the fed-batch culture was carried out by keeping the glucose concentration at 30g/L, more than 140 g/L of L-lactic acid was produced with a product yield of 83%. In the case of the batch culture with 200g/L of initial glucose concentration, 121g/L of L-lactic acid was obtained but the low product yield based on the amount of glucose consumed. In the case of a continuous culture, 1.5g/L/h of the volumetric productivity with a product yield of 71% was achieved at dilution rate of $0.024\;h^{-1}$. Basis on these results three processes were evaluated by simple variable cost estimation including carbon source, steam, and waste treatment costs. The total variable costs of the fed-batch and continuous cultures were 88% and 140%, respectively, compared to that of batch culture. The fed-batch culture with high L-lactic acid concentration and high product yield decreased variable costs, and was the best-suited for the industrial production of L-lactic acid.