• 상하수도학회지
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• 제10권2호
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• pp.117-123
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• 1996

A bench-scale continuous activated sludge system was operated in order to study the effects of solid waste landfill leachate on municipal wastewater treatment. The leachate sample was collected from Nanjido landfill. During the 7 weeks of operational period, the leachate content in the influent fed to the system was increased stepwise from 3% to 5% and 7%. The solids retention time was the major process control parameter, and it was 10 days. With the municipal wastewater alone, COD removal was 75%. The removal percents, however, decreased to 60% and 45% when the leachate content was 3% and 7%, respectively. For the wastewater spiked with the leachate, the sludge production was higher than for the municipal wastewater alone. Sludge settleability determined by SVI deteriorated with the increase of leachate content. The specific oxygen uptake rate, however, was measured higher as leachate content increased.

• 대한환경공학회지
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• 제31권8호
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• pp.655-662
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• 2009

원통형 여과장치의 실규모 설계 및 운전에 필요한 기초자료를 얻기 위하여 산출유량을 단계적으로 증가시키는 파일럿 실험을 수행하면서 수질지표들과 폐색도 진행을 조사하였다. 유량을 0.8 L/min에서 2.4 L/min로 증가시키는 경우 BOD, SS, 그리고 탁도의 제거율은 각각 약 80%, 95% 이상, 그리고 90% 이상으로 거의 일정하게 유지되었으나 COD 제거율은 44%에서 29%로 감소하였다. 산출유량이 증가할수록 오염물 단위농도를 제거하는데 소요되는 체류시간은 감소하였으며, 1 mg-COD/L를 제거하는데 필요한 체류시간은 산출유량 0.8 L/min인 경우 83분이었고 2.4 L/min에서는 45분이어서 양수율이 낮은 것보다는 높은 것이 호소의 오염제거에 더 유리함을 알 수 있었다. 여과장치의 폐색은 표층에서 집수관쪽으로 진행하며, 산출유량이 증가하면 폐색도도 증가하지만 2년 이상의 운전에도 폐색이 문제되지는 않아 본 장치가 호소의 수질개선에 효과적으로 사용될 수 있을 것으로 기대되었다.

• KSBB Journal
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• 제19권3호
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• pp.192-199
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• 2004

본 연구에서는 글루타치온의 생산 공정을 개발하기 위해 효모의 성장특성, 글루타치온의 생산성 및 공정 모니터링에 관하여 조사하였다. 초기 pH가 4인 경우 40 mg/L 정도의 높은 글루타치온이 생산되었으며 배양온도에 따른 글루타치온의 생산은 3$0^{\circ}C$에서 가장 높게 나타났다. 그리고 최소 배지에 첨가한 시스테인은 배양 12시간에 넣었을 때 글루타치온의 생산성이 높게 나타났다. 생물 반응기를 이용한 회분식 배양에서 기질 농도에 따른 S. cerevisiae 성장 특성 및 글루타치온 생산은 글루코스 농도 20 g/L에서 글루타치온 생산량이 55 mg/L로 가장 높았다. 최소 배양액에 배양 초기에 0.5 % (v/v) 글라이신과 글루탐산을 각각 첨가하고 배양 11시간에 시스테인을 0.5% (v/v) 추가로 첨가한 경우에 글루타치온의 생산량이 많았다. 회분식 배양 후 기질을 첨가하는 유가식 발효 공정에서는 반응기내 글루코스 농도가 0.5 g/L 이하로 유지되도록 글루코스를 계단식으로 공급하였을 때 글루타치온은 약 102 mg/L로 높은 생산량을 나타내었다. 2차원 형광 센서를 이용하여 글루타치온 생산 공정의 온라인 모니터링은 배양액의 배지 조성이나 성장 특성 등 배양기내의 환경 변화에 따라 형광 영역 및 세기가 다르게 나타났으며 실시간 모니터링 된 형광 데이터는 기질 및 생산물 그리고 균체 성장 등의 각종 공정 변수와 좋은 상관성을 보였다. 따라서 2차원 형광 센서에 의한 모니터링은 글루타치온 대량 생산을 위한 실시간 모니터링에 매우 효과적이라 할 수 있다.

• Nuclear Engineering and Technology
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• 제27권1호
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• pp.84-95
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• 1995

Application of computer software to safety-critical systems is on the increase. To be successful, the software must be designed and constructed to meet the functional and performance requirements of the system. For safety reason, the software must be demonstrated not only to meet these requirements, but also to operate safely as a component within the system. For longer-term cost consideration, the software must be designed and structured to ease future maintenance and modifications. This paper present a software engineering process for the production of safety-critical software for a nuclear power plant The presentation is expository in nature of a viable high quality safety-critical software development. It is based on the ideas of a rational design process and on the experience of the adaptation of such process in the production of the safety-critical software for the Shutdown System Number Two of Wolsong 2, 3 & 4 nuclear power generation plants. This process is significantly different from a conventional process in terms of rigorous software development phases and software design techniques. The process covers documentation, design, verification and testing using mathematically precise notations and highly reviewable tabular format to specify software requirements and software design. These specifications allow rigorous, stepwise verification of software design against software requirements, and code against software design using static analysis. The software engineering process described in this paper applies the principle of information-hiding decomposition in software design using a modular design technique so that when a change is' required or an error is detected, the affected scope can be readily and confidently located. It also facilitates a sense of high degree of confidence in the ‘correctness’ of the software production, and provides a relatively simple and straightforward code implementation effort.

• Mycobiology
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• 제46권2호
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• pp.129-137
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• 2018

Black rot disease in orchids is caused by the water mold Phytophthora palmivora. To gain better biocontrol performance, several factors affecting growth and antifungal substance production by Pseudomonas aeruginosa RS1 were verified. These factors include type and pH of media, temperature, and time for antifungal production. The results showed that the best conditions for P. aeruginosa RS1 to produce the active compounds was cultivating the bacteria in Luria-Bertani medium at pH 7.0 for 21 h at $37^{\circ}C$. The culture filtrate was subjected to stepwise ammonium sulfate precipitation. The precipitated proteins from the 40% to 80% fraction showed antifungal activity and were further purified by column chromatography. The eluted proteins from fractions 9-10 and 33-34 had the highest antifungal activity at about 75% and 82% inhibition, respectively. SDS-PAGE revealed that the 9-10 fraction contained mixed proteins with molecular weights of 54 kDa, 32 kDa, and 20 kDa, while the 33-34 fraction contained mixed proteins with molecular weights of 40 kDa, 32 kDa, and 29 kDa. Each band of the proteins was analyzed by LC/MS to identify the protein. The result from Spectrum Modeler indicated that these proteins were closed similarly to three groups of the following proteins; catalase, chitin binding protein, and protease. Morphological study under scanning electron microscopy demonstrated that the partially purified proteins from P. aeruginosa RS1 caused abnormal growth and hypha elongation in P. palmivora. The bacteria and/or these proteins may be useful for controlling black rot disease caused by P. palmivora in orchid orchards.

• Journal of Microbiology and Biotechnology
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• 제30권1호
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• pp.136-145
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• 2020

Chlorella sp. HS2, which previously showed excellent performance in phototrophic cultivation and has tolerance for wide ranges of salinity, pH, and temperature, was cultivated heterotrophically. However, this conventional medium has been newly optimized based on a composition analysis using elemental analysis and ICP-OES. In addition, in order to maintain a favorable dissolved oxygen level, stepwise elevation of revolutions per minute was adopted. These optimizations led to 40 and 13% increases in the biomass and lipid productivity, respectively (7.0 and 2.25 g l^-1d^-1 each). To increase the lipid content even further, 12 h heat shock at 50℃ was applied and this enhanced the biomass and lipid productivity up to 4 and 17% respectively (7.3 and 2.64 g l^-1d^-1, each) relative to the optimized conditions above, and the values were 17 and 14% higher than ordinary lipid-accumulating N-limitation (6.2 and 2.31 g l^-1d^-1). On this basis, heat shock was successfully adopted in novel Chlorella sp. HS2 cultivation as a lipid inducer for the first time. Considering its fast and cost-effective characteristics, heat shock will enhance the overall microalgal biofuel production process.

• 한국물환경학회지
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• 제21권5호
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• pp.464-469
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• 2005

In the nonwoven fabric filter bioreactor (NFBR), both the construction and the operation costs could be saved because a high concentration of microorganism can be maintained in the reactor as in the membrane bioreactor. However, the NFBR process has been investigated only under aerobic and/or anoxic conditions, In this research, a basic anaerobic treatment experiment was performed at $35^{\circ}C$ by feeding an airtight NFBR with a concentrated synthetic organic wastewater. The organic loading rate (OLR) of the NFBR was increased stepwise from $0.25kg\;COD/m^3-day$ to $0.77kg\;COD/m^3-day$ by gradually decreasing the hydraulic retention time from 20 days to 13 days. The results of the research showed that the best COD removal efficiency achieved at the OLR of $0.67kg\;COD/m^3-day$ with a value of 99.3%. The methane content of the produced gas was highest with a value of 61.2% at the OLR of $0.33g\;COD/m^3-day$. The highest methane production rate was $0.89g\;COD/m^3-day$ at the same OLR. The operation was terminated at the OLR of $0.77kg\;COD/m^3-day$ because of the deterioration in COD removal efficiency, gas production rate, and the methane content of the gas. Further researches are recommended for the NFBR to be employed for anaerobic treatment of organic wastewaters.

• 한국물환경학회지
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• 제20권6호
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• pp.583-588
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• 2004

This research examined the treatment efficiency and methane production rate in treating slurry-type swine waste using UASB (upflow anaerobic sludge blanket) reactor. The UASB reactor was operated at an organics volumetric loading rate (VLR) of $2.6-15.7kgCOD/m^3/day$. A stepwise increase of the VLR resulted in a temporary deterioration in the COD removal rate in UASB reactor but recovered quickly. The COD removal rate were 65-70% for VLR up to $5 kgCOD/m^3/day$. When organics VLR was $10kgCOD/m^3/day$, the COD removal rate decreased sharply and there was loss of 17.537g of the seeding biomass due to sludge washout. This result indicated that the UASB system cannot be adapted to more than $10kgCOD/m^3/day$ of VLR. As the organic load increased from 2.6 to $15.7kgCOD/m^3/d$, the biogas production rate varied from 3.2 to 10.8 L/d and the methane conversion rate of the organic matter varied from 0.30 to $0.23m^3CH_4/kg\;COD_{removed}$. The methane content showed the range of 70.1-81.5% during the experimental period. The volatile solids (VS) removal efficiency was similar at the low VLR (< $5 kgCOD/m^3/day$), but it decreased sharply at the high VLR (> $5 kgCOD/m^3/day$). The VS reduction rate was, moreover, large those of COD. The result shows that hydraulic retention time above 2 days is essential in case of treating wastewater containing 1% of solids.

• Journal of Preventive Medicine and Public Health
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• 제25권1호
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• pp.64-72
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• 1992

To provide the information necessary for the insurance medicine management plan, price discount rates among the insurance medicines were studied. A total of 2,107 items of insurance medicine of which prices were discounted via governmental inspections of real transactional process of insurance medicine were analysed. The conclusions are as follows; 1. Among the variables relevant to the characteristics of manufacturers, price discount rates of insurance medicines were statistically significant with production rankings of manufacturers, incorporation year, existence of investments by foreign corporation, existence of a research institute, and enrollment in the exchange. And among the variables relevant to the properties of medicines, the number of enrolled items which have the same components, classification, the date of new enrollment, the sales of items, and the number of raw materials in the items were statistically significant. 2. Stepwise multiple regression was done to identify the factors which affect the price discount rates of insurance medicines. The number of enrolled items which have the same components, production rankings of manufactures, classification number (medicines for function of tissue cells), incorporation year(1940-1949), existence of investments by foreign corporations, classification number (anti-germ medicines), number of raw materials In the items, the sales of items, and medicines whose major objective is not treatment were significant variables and the $R^2$-value for these variables was 21.2%. Considering all of the above results, for management of insurance medicines, it seems important that the real transactional prices of insurance medicines should be identified systematically, focusing on the properties which affect the price discount rates of insurance medicines.

• Applied Biological Chemistry
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• 제28권4호
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• pp.233-238
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• 1985

Glucoamylase를 $ZrO_2$로 피복된 96% porous glass에 azo-linkage를 형성시켜 결합하게 한후, 2.5% glutaraldehyde로 처리하여 효소를 고정화시켰다. 효소기질로는 용해도가 높고 점도가 낮은 30% enzyme thinned cornstarch (dextrose equivalent 값 : 24)를 사용하여 plug flow-column reactor에서 연속반응시켰다. 반응 최적 pH는 수용성효소의 5.0보다 alkaline 쪽으로 기울어져 7.0으로 나타났고, 고정화반응에 따라 열안정성이 높아지고 $40{\sim}60^{\circ}C$에서 최적 온도범위를 가리키며, Km값은 수용성 효소의 1.25mM보다 낮은 1.04mM값을 보여 주었다. 따라서, pH 7.0, $45^{\circ}C$에서 160시간 동안 corn starch를 기질로 효소반응을 시켜 glucose 90.3%, maltose 8.0%인 DE값 94.0인 전분당분해산물을 획득할 수 있었다.