• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 춘계학술대회논문집B
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• pp.13-18
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• 2000

The objective of the Present study is to investigate the performance of electronic scale mitigation unit(ESMU), which reduces the amount of scale in a heat exchanger. A plate heat exchanger with 20 thermal plates is used for the tests. In order to accelerate the rate of fouling in a laboratory test artificial hard water of 2000 ppm(as $CaCO_3$) is recirculated at a flow rate 5L/min throughout the tests. The overall heat trans(or coefficients and fouling factors are examined. Results show that the ESMU technology can significantly reduce the scale deposits.

• Journal of Microbiology and Biotechnology
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• 제15권4호
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• pp.787-791
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• 2005

Mutation and its pilot-scale fermentation were conducted for the production of teicoplanin from Actinoplanes teichomyceticus. The fermentation medium was optimized by replacement and Plackett-Burman experimental design. A maximum production of 1,500 mg/l teicoplanin was obtained by pilot-scale fermentation in an optimized medium containing (g/l): 30 g maltodextrin, 5 g glucose, 5 g yeast extract, 5 g soybean meal, 0.5 g $MgSO_4{\cdot}7H_2O$, 0.1 g NaCl, 0.1 g $CaCl_2{\cdot}2H_2O$, and 50 g Diaion HP-20. The production of teicoplanin was improved 3-fold from the parental strain by mutation, media optimization, and fermentation, and laboratory-scale fermentation was successfully demonstrated in a pilot-scale fermenter for the industrial production of teicoplanin.

• 한국표면공학회지
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• 제26권5호
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• pp.255-262
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• 1993

Major parameters determining the extent of Ca utilization were investigated for their calcination/sulfation behavior of limestone in the AFBC(Atmospheric Fluidized Bed Combustion) environments. Three different particle sizes of Fredonia limestone were investigated in the lab-scale tubular reactor. The results of the calcination codnversion of limestone imply that thesd decomposition rate of CaCO3 into CaO is dependent on the amount of heat which limestone absorbed. Hg porosimeter measurement of calcined limestone illustrated that surface area and pore volume are increased with decreasing particle size. Raw Fredonia limestone and sequentially as well as simultaneously calcined/sulfated limestones were also examined using SEM. The SEM Studied showed that the surface of the calcined limestone particles is more diffusive nature than that of the parent calcite. However, the sulfur distribution pattern of simultaneously-treated particles and that of the se-quentially-treated one shows no difference.

• 방사성폐기물학회지
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• 제19권4호
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• pp.469-477
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• 2021

Safe storage of spent nuclear fuel in deep underground repositories necessitates an understanding of the long-term alteration of metal canisters and buffer materials. A small-scale laboratory alteration test was performed on metal (Cu or Fe) chips embedded in compacted bentonite blocks placed in anaerobic water for 1 year. Lactate, sulfate, and bacteria were separately added to the water to promote biochemical reactions in the system. The bentonite blocks immersed in the water were dismantled after 1 year, showing that their alteration was insignificant. However, the Cu chip exhibited some microscopic etch pits on its surface, wherein a slight sulfur component was detected. Overall, the Fe chip was more corroded than the Cu chip under the same conditions. The secondary phase of the Fe chip was locally found as carbonate materials, such as siderite (FeCO₃) and calcite ((Ca, Fe)CO₃). These secondary products can imply that the local carbonate occurrence on the Fe chip may be initiated and developed by an evolution (alteration) of bentonite and a diffusive provision of biogenic CO₂ gas. These laboratory scale results suggest that the actual long-term alteration of metal canisters/bentonite blocks in the engineered barrier could be possible by microbial activities.

• Mycobiology
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• 제43권4호
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• pp.467-474
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• 2015

Development of efficient substrate formulas to improve yield and shorten production time is one of the prerequisites for commercial cultivation of edible mushrooms. In this study, fifteen substrate formulas consisting of varying ratios of palm press fibre (PPF), mahogany sawdust (MS), Gmelina sawdust, wheat bran (WB), and fixed proportions of 1% calcium carbonate ($CaCO_3$) and 1% sucrose were assessed for efficient Lentinus squarrosulus production. Proximate compositions of mushrooms produced on the different substrate formulas were also analysed and compared. Substrate formulations containing 85% PPF, 13% WB, 1% $CaCO_3$, and 1% sucrose were found to produce the highest carpophore yield, biological efficiency and size (206.5 g/kg, 61.96%, and 7.26 g, respectively). Days to production (first harvest) tended to increase with an increase in the amount of WB in the substrate formulas, except for PPF based formulas. The addition of WB in amounts equivalent to 8~18% in substrate formulas containing 80~90% PPF resulted in a decrease in the time to first harvest by an average of 17.7 days compared to 80~90% MS with similar treatment. Nutritional content of mushrooms was affected by the different substrate formulas. Protein content was high for mushrooms produced on formulas containing PPF as the basal substrate. Thus, formulas comprising PPF, WB, $CaCO_3$, and sucrose at 85% : 13% : 1% : 1%) respectively could be explored as starter basal ingredients for efficient large scale production of L. squarrosulus.

• 한국환경농학회지
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• 제30권1호
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• pp.31-36
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• 2011

축산농가에서 발생되는 돈분 슬러리의 처리 능력을 평가하기 위하여 Full-scale의 단상 혐기성 소화조에서 중온소화와 고형물 체류시간을 20일로 하여 연속식으로 운전하면서 성능평가 및 특성연구를 실시하였다. 운전기간 중 알칼리도는 약 4,000 mg/L(3,500~9,000 mg/L as $CaCO_3$)이였고, 소화조내의 pH는 7.5~8.0 범위로 약간 높은 경향이었으나 pH는 안정적이었다. 바이오가스의 발생량은 OLR 1.2 $g{\cdot}COD/L{\cdot}day$에서 0.69 L/L/day의 바이오가스를 생산하였고, 제거된 COD를 바탕으로 계산된 메탄가스 발생량은 63% 수준이였다. 생산된 바이오가스 중 메탄가스 함량은 65~70%이었고, CO2는 약 30% 전후였으며, 열병합 발전을 실시하였을 때 총전력요구량의 50~75% 수준을 공급하였다. 또한 발전기 부하가 5~9 kW시 평균 1 kWh의 전력을 생산하기 위한 바이오가스 소모량은 약 1.8 $m^3$이였다. 따라서 실제 규모의 plant에서 약 500일간 운전한 결과 유입되는 돈분 슬러리의 TS 농도에 상관없이 소화조 내에 일정 농도의 유기물을 확보할 수 있었고, 바이오가스의 발생량은 일반적인 축산분뇨 가스 발생량 보다 높게 나타나 단상 혐기성 소화공정으로 고효율 처리가 가능한 것으로 나타났다.

• 한국지하수토양환경학회지:지하수토양환경
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• 제18권7호
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• pp.73-80
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• 2013

Fine suspended solids from coal mine drainage were treated in the treating plant, using two different pilot-scale inclined clarifiers: radial and lamella types. Suspended solids in the mine drainage were monitored along with other geochemical factors, and metal contents. Fe and Mn are the main chemical components in the drainage, which exist predominantly as total metal forms, whereas dissolved portion is negligible. The raw mine drainage is subject to physical and chemical treatment using $CaCO_3$ and NaOH, therefore the suspended solids are thought to be composed of Fe and Mn precipitates, possibly $Fe(OH)_3$, along with carbonate precipitates. The elemental composition of precipitates are confirmed by SEM-EDS analysis. As nearly all the dissolved ions were precipitated in the primary process by $CaCO_3$, no further aeration or prolonged oxygenation are of necessity in this plant. Adoption of inclined clarifier proved to be effective in treating fine suspended solids in the current plant. Successful application of the inclined clarifier will also be beneficial to improve the current treating process by excluding the current application of chemical agent in the first stage. The final effluents from the pilot plant meet the national standards and the low dissolved Fe and Mn contents are expected not to cause secondary precipitation after discharge.

• 전기학회논문지
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• 제66권7호
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• pp.1066-1071
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• 2017

Recently high voltage impulse (HVI) technique has been extensively studied for desalting processes to control the $CaCO_3$ scale formation in industrial water practices such as power plant, boiler, and heat exchange operations. Investigation of the operational parameters for the HVI is important, however, those had not been reported yet. In this study, the effect of initial feed volume and contact time on reduction of calcium ion concentration by the HVI technique was investigated. Initial feed volumes of artificial hard water which contained 100 mg/L of $Ca^{2+}$, were set to 1, 2, and 3 L respectively. After 24hr of HVI contact with 12kV, $Ca^{2+}$ ion was reduced to 50, 29 and 19 % of their initial concentration, indicating that calcium removal increased as initial feed volume decreased. This implies the applied HVI pulse energy per unit mass of calcium is important parameter determining overall desalting efficiency. A series of extended operations of HVI up to 30 days verified the long term stability of the HVI system. The calcium ion declined to 40 mg/L after 2~3 days, and further reduction of calcium was not achieved, indicating that optimum operation time could be 2~3 days under these experimental conditions. Consequently, it was confirmed that the important operational parameter of HVI technique is initial feed volume and contact time as well as the applied voltage that was already proven in the previous study.

• 자원환경지질
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• 제41권2호
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• pp.201-210
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• 2008

국내 폐광산 주변 중금속 오염 농경지 토양 복원을 위해 석회(CaO)와 분쇄한 석회암($CaCO_3$)을 안정화제로 이용한 토양 안정화 공법의 효율을 규명하는 배치 및 대형 칼럼실험을 실시하였다. 오염토양은 경북 군위군에 위치한 아연 폐광산 지역의 오염 농경지 토양을 이용하였으며, 안정화제의 함량은 오염토양 대비 0, 0.5, 2, 5%로 다양하게 적용함으로써, 안정화제에 의해 토양으로부터 용출되는 중금속 농도 변화를 시간에 따라 측정하여 안정화제의 중금속 저감 효율을 규명하였다. 배치실험 결과, 가루상의 석회나 석회암 0.5%를 토양과 혼합하여 안정화제로 사용한 경우, 오염토양으로부터 As, Cd, Pb, Zn의 중금속 용출 농도는 안정화제를 사용하지 않은 토양으로부터의 용출 농도를 기준으로 각각 70, 77, 94, 그리고 95% 감소하여 중금속 용출 저감 효과가 매우 높은 것으로 나타났다. 토양 객토법을 모사한 대형 칼럼실험 결과, 2% 입상 석회 첨가에 의해서 As, Cd, Zn의 토양 용출은 안정화제를 사용하지 않은 토양 용출 농도를 기준으로 각각 63, 97, 98% 감소하였다. 입상 석회암을 안정화제로 이용한 칼럼에서는 2% 석회암 첨가에 의해서 As 용출 농도는 135.6${\mu}g/L$에서 30.2 ${\mu}g/L$ 감소하여 약 46% 이상의 감소율을 나타내었으며, Cd와 Zn의 경우에는 97% 이상 감소하였다. 배치 및 칼럼실험 결과 석회암의 중금속 용출 저감 효율이 석회의 저감 효율과 매우 비슷한 것으로 나타나, 토양으로부터 중금속을 안정화시키는데 입상 석회와 석회암 모두 효과가 매우 좋은 것으로 나타났다. 토양 산성화 방지를 위해 토양개량제로 주로 사용하였던 석회의 과도한 토양 내 첨가가 토양의 급격한 pH 증가를 일으켜 농작물 재배에 악 영향을 주게 되는 한계를 극복하기 위하여, 본 배치 및 대형 칼럼실험을 통하여 토양 내 첨가에 의한 pH 증가가 거의 없으며 비용 측면에서도 석회보다 훨씬 저렴하지만 중금속 용출 저감 효과가 비슷한 석회암이 중금속 오염 농경지 토양 복원을 위한 새로운 안정화제로 유용하게 사용될 수 있음을 입증하였다.

• 한국지반환경공학회 논문집
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• 제13권9호
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• pp.45-51
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• 2012

터널 내로 유입되는 지하수에 의해 시멘트 수화물인 수산화칼슘$(Ca(OH)_2)$이 토중의 미생물 반응, 유기물의 산화 등에 의해 발생되는 이산화탄소$(CO_2)$와 차량의 배기가스$(SO_3)$ 등과 반응하여 그 반응물이 터널 상부에 설치된 배수공 내에 침전됨으로 인하여 배수공 클로깅 현상이 발생하게 된다. 이러한 현상으로 인하여 터널 배수 시스템의 수리기능저하가 발생하게 되면 간극수압이 증가 하여 누수를 가속화 시키며, 라이닝의 열화를 초래하게 된다. 본 연구는 배수공 클로깅 현상을 방지하기 위하여 퀀텀스틱과 자화장치를 개발하였으며 서울 남산 ${\bigcirc}{\bigcirc}$ 터널과 지하철 ${\bigcirc}{\bigcirc}{\bigcirc}$ 공구에서의 현장실험을 통하여 위 기술의 현장 적용성을 규명하는데 그 목적이 있다. 배수공에 요소기술을 적용한 배수관을 삽입한 후 주기적으로 육안관측을 수행하였고 최종적으로 발생된 스케일의 SEM 및 XRD 분석을 수행하였다. 그 결과 요소기술을 적용하였을 경우 스케일 생성량이 현저히 줄었으며, 특히 퀀텀스틱이 자화장 치에 비하여 그 효과가 우수하였다. 따라서 기존의 노후터널 배수공에 퀀텀스틱 또는 자화장치를 배수공에 적용하였을 경우, 배수공 의 클로깅 현상을 어느 정도 저감시킬 수 있을 것으로 판단된다.