• 상하수도학회지
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• 제32권4호
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• pp.357-361
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• 2018

Forward osmosis (FO) process has been attracting attention for its potential applications such as industrial wastewater treatment, wastewater reclamation and seawater desalination. Particularly, in terms of fouling reversibility and operating energy consumption, the FO process is assumed to be preferable to the reverse osmosis (RO) process. Despite these advantages, there is a difficulty in the empirical step due to the lack of separation and recovery techniques of the draw solution. Therefore, rather than using FO alone, recent developments of the FO process have adapted a hybrid system without draw solution separation/recovery systems, such as the FO-RO osmotic dilution system. In this study, we investigated the performance of the hollow fiber FO module according to various operating conditions. The change of permeate flow rate according to the flow rates of the draw and feed solutions in the process operation is a factor that increases the permeate flow rate, one of the performance factors in the positive osmosis process. Our results reveal that flow rates of draw and feed solutions affect the membrane performance, such as the water flux and the reverse solute flux. Moreover, use of hydraulic pressure on the feed side was shown to yield slightly higher flux than the case without applied pressure. Thus, optimizing the operating conditions is important in the hollow fiber FO system.

• 멤브레인
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• 제1권1호
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• pp.78-95
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• 1991

미국 캘리포니아주 Orange County에 위치한 Water Factory 21(WF-21)은 생물학적 처리공정을 거친 도시하수를 재생하여, 이 재생수를 지하수지층으로 유입되는 해수의 침투를 막기 위한 Reinjection System에 이용하고 있다. 장치 구성 공정은 Lime처리, Air Stripping, 사여과, 활성탄처리, 역삼투막 및 염소처리 등으로 이루어지며, 이에 대한 각 처리공정의 효율성에 대하여 실험을 실시하였다. 3년간의 장기간에 걸친 실험결과로부터, 도시하수에 대한 RO Membrane 처리수는 음료 수질 기준에 적합한 고수질의 물을 생성할 수 있음을 입증했다. Pilot Plant 실험에선 Lime Clarifier만으로 전처리를 실시하여 성공적인 결과를 얻었으며, 또한 저압 (250 psi)이 적용된 새로운 Membrane을 사용하여 에너지 절약을 통한 비용 절감 효과에 대한 실험도 상당한 가능성을 보여주었다.

• 한국토양비료학회지
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• 제22권3호
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• pp.180-190
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• 1989

본(本) 연구(硏究)는 토양(土壤)의 숙성화정도(熟成化程度)에 따른 토양(土壤)의 이화학성(理化學性) 변화(變化) 양상(樣相)을 구명(究明)하여 벼 수량증대(收量增大)를 위(爲)한 토양개량(土壤改良)과 관리(管理)의 자료(資料)를 얻고져 실시(實施)하였다. 1. 문포통(文浦統)의 이앙전(移秧前) 토양(土壤) 및 지하수(地下水) 염농도(鹽濃度)는 간척(干拓)6년차(年次)에서 각각(各各) 0.60%와 1.84%로 염해(鹽害)가 우려(憂慮)되나 20년차(年次)부터는 수도재배(水稻栽培)가 가능(可能)한 함량(含量)이었고, 포리통(浦里統)은 12년차(年次)까지 염해우려(鹽害憂慮)와 그 이후(以後)부터는 벼 안전재배(安全栽培)가 가능(可能)한 함량(含量)이었다. 2. 토양입경(土壤粒徑)은 토양(土壤)이 숙성화(熟成化)됨에 따라 문포통(文浦統)은 표(表) 심토(心土) 공(共)히 모래함량(含量)은 부(負)의 상관(相關), 점토함량(粘土含量)은 정(正)의 상관(相關)을 보인 반면(反面) 포리통(浦里統)은 이와 상반(相反)되는 경향(傾向)이었다. 3. 토양(土壤)이 숙성화(熟成化)됨에 따라 N-계수(係數), Atterberg limits는 양(兩) 토양(土壤) 공(共)히 부(負)의 상관(相關)을 보인 반면(反面) Clay-Activity는 정(正)의 상관(相關)을 보였고 cole는 문포통(文浦統)에서 정상관(正相關), 포리통(浦里統)은 부(負)의 상관(相關)을 보였다. 4. 토심별(土深別) 원추저항(圓錐抵抗)은 문포통(文浦統)의 간척(干拓) 6년차(年次) 표토(表土)(2.5 cm)에서 $62.9kg/cm^2$(지표경도(指標硬度) 32mm), 20년차(年次)는 토심(土深) 15 ㎝에서 $24.9kg/cm^2$(지표경도(指標硬度) 28mm), 27년차(年次)는 토심(土深) 22.5 cm에서 $16.7kg/cm^2$(지표경도(指標硬度) 26mm)의 저항(抵抗)을 보인 반면(反面) 포리통(浦里統)은 간척(干拓)12년차(年次)까지 토심(土深) 15~20 cm의 저항치(抵抗値)가 농기계(農機械)의 사용(使用)이 곤란(困難) 및 불가능(不可能)한 저항치(抵抗値) $3kg/cm^2$을 보였고 23년차(年次)부터는 경반층(硬盤層)의 생성(生成)으로 농기계사용(農機械使用)이 가능(可能)한 $3kg/cm^2$이상(以上)을 보였다. 5. 간척년대별(干拓年代別) 점토광물(粘土鑛物)의 종류(種類) 및 변화(變化)는 없었으며, 양(兩) 토양(土壤) 공(共)히 주점토광물(主粘土鑛物)은 Illite 및 Kaolinite 광물(鑛物)들이며, 부점토광물(副粘土鑛物)을 Montmorillonite, Vermiculite이었다.

• 한국물환경학회지
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• 제26권2호
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• pp.289-296
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• 2010

The purpose of this study is to evaluate various pre-treatment methods and proprieties of water quality for wastewater reuse using reverse osmosis (RO) processes. Secondary effluents were sampled from wastewater treatment plants and lab scale pre-treatments and RO filtration test were conducted systematically. Specifically, different types of pre-treatments, such as coagulation, microfiltration and ultrafiltration, were employed to evaluate the removal efficiency of particle and organic matters which may affect the membrane fouling rate. RO process was later added to eliminate trace amounts of remaining organic matters and salt from the raw water for wastewater reclamation. The permeate through the RO process satisfied water quality regulations for industrial water uses. The experimental results showed that the initial fouling tendency differed not only by the feed water properties but also by the membrane characteristics. Membrane fouling was greater for the membranes with large surface roughness, regardless of the hydrophobicity and zeta potentials. Thus both careful consideration of pre-treatment options and proper selection of RO membrane are of paramount importance for an efficient operation of wastewater treatment.

• Asian-Australasian Journal of Animal Sciences
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• 제23권1호
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• pp.47-51
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• 2010

The objective of this study was to understand changes of plasma metabolites, hormones, and mRNA level of cytoplasmic phosphoenolpyruvate carboxykinase (PEPCK-C) in liver in spontaneous clinical ketosis; 10 clinically ketotic cows and 10 healthy cows were chosen from the same dairy farm. Eleven blood parameters and liver fat content were measured in all cows, and mRNA levels of PEPCK-C in liver were measured by semi-quantitative reverse transcription (RT) polymerase chain reaction (PCR). In ketotic cows, concentration of plasma glucose decreased (p<0.01), concentration of plasma nonesterified fatty acids (NEFA) and $\beta$-hydroxybutyric acid (BHBA) increased (p<0.01), liver fat content (18.8% wet weight) and activity of plasma aspartate aminotransferase (AST) increased (p<0.01), but concentration of plasma total bilirubin (TBIL), $\gamma$-glutamyl transpeptidase ($\gamma$-GT), and cholinesterase (CHE) increased (p>0.05). In addition, concentration of plasma insulin decreased (p<0.05), concentration of plasma glucagons decreased (p>0.05), and mRNA level of PEPCK-C in liver increased (p<0.05). It is concluded that the adaptative changes of metabolites, hormones, and mRNA level of PEPCK-C in ketotic cows were in favor of the enhancement of gluconeogenesis, the decrease of fat mobilization and the relief of ketosis, but these were still inadequate to relieve ketosis.

• Journal of Microbiology and Biotechnology
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• 제27권8호
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• pp.1379-1385
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• 2017

The content of taxol in the bark of yews is very low, and this is not affordable from the environmental point of view. Thus, it is a necessity to look for alternative sources of taxol production to solve its supply. Currently, a large portion of the taxol in the market comes from chemical semi-synthesis, but the semi-synthetic precursors such as baccatin III and 10-deacetyl-baccatin III are extracted from needles and twigs of yew trees. Taxol-producing fungi as a renewable resource is a very promising way to increase the scale of taxol production. Our group has obtained a taxol-producing endophytic fungus, Aspergillus niger subsp. taxi HD86-9, to examine if A. niger can produce the taxanes. Six compounds from the fermentation broth of strain HD86-9 were isolated and identified by $^1H$ NMR, $^{13}C$ NMR, and ESI-MS. The results showed that the six compounds included four taxane diterpenoids (taxol, cephalomannine, baccatin III, and 10-deacetyl-baccatin III) and two non-taxane compounds (${\beta}-sitosterol$ and flavonoid isovitexin). The study verified that the taxanes can be produced by the A. niger, which is very important to taxol production via chemical semi-synthesis. Additionally, the finding is potentially very significant to solve the taxol semi-synthetic precursors extracted from needles and twigs of yew trees, and the precursor production can be easily increased through the culture condition optimization, genetic breeding, and metabolic engineering of the A. niger.

• 한국환경과학회지
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• 제15권10호
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• pp.919-928
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• 2006

The present study applied an atmospheric flow field model in Gwangyang-Bay which can predict local sea/land breezes formed in a complex terrain lot the development of a model that can predict short term concentration of air pollution. Estimated values from the conduct of the atmospheric flow field were used to evaluate and compare with observation data of the meteorological stations in Yeosu and the Yeosu airport, and the effect of micrometeorology of surround region by the coastal area reclamation was predicted by using the estimated values, Simulation results, a nighttime is appeared plainly land breezes of the Gwangyang-bay direction according to a mountain wind that formed in the Mt. of Baekwooun, Mt. of Youngchui. Land winds is formed clockwise circulation in the north, clockwise reverse direction in the south with Gangyang-bay as the center. Compared with model and observation value, Temperature is tend to appeared some highly simulation value in the night, observation value in the daytime in two sites all, but it is veil accorded generally, the pattern of one period can know very the similarity. And also, wind speed and wind direction is some appeared the error of observation value and calculation results in crossing time of the land wind and sea land, it can see that reproducibility is generally good, is very appeared the change land wind in the nighttime, the change of sea wind in the daytime. And also, according to change of the utilization coefficient of soil before and after development with Gwangyang-Bay area as the center. Temperature after development was high $0.55\sim0.67^{\circ}C$ in the 14 hoots, also was tend to appear lowly $0.10\sim0.22^{\circ}C$ in the 02 hours, the change of u, v component is comparatively tend to reduced sea wind and land wind, it is affected ascending air current and frictional power of the earth surface according to inequality heating of the generation of earth surface.

• 한국환경과학회지
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• 제19권11호
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• pp.1423-1436
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• 2010

The effects of meteorological and reclaiming conditions on the reduction of suspended particles are investigated using a computational fluid dynamics (CFD) model with the k-$\varepsilon$ turbulence closure scheme based on the renormalization group (RNG) theory. Twelve numerical experiments with different meteorological and reclaiming conditions are performed. For identifying the meteorological characteristics of the target area and providing the inflow conditions of the CFD model, the observed data from the automatic weather station (AWS) near the target area is analyzed. Complicated flow patterns such as flow distortion, horse-shoe vortex, recirculation zone, and channeling flow appeared due to the topography and buildings in the domain. Specially, the flow characteristics around the reclamation area are affected by the reclaiming height, reclaiming size and windbreak height. Reclaiming height affected the wind speed above the reclaiming area. Windbreak induces more complicated flow patterns around the reclaiming area as well as within the reclaiming area. In front of the windbreak, flow is distorted as it impinges on the windbreak. As a result, upward flow is generated there. Behind the windbreak, a secondary circulation, so called, a recirculation zone is generated and flow is reattached at the end of the recirculation zone (reattachment point). At the lower part of the recirculation zone, there is a reverse flow toward the windbreak. Flow passing to the reattachment point starts to be recovered. Total amounts of suspended particles are calculated using the frictional and threshold frictional velocities, erosion potential function, and the number of surface disturbance. In the case of a 10 m-reclaiming and northerly wind, the amount of suspended particles is largest. In the presence of 5 m windbreak, the friction velocity above the reclaiming area is largely reduced. As a result, the total amount of the suspended particles largely decreases, compared to the case with the same reclaiming and meteorological conditions except for the windbreak The calculated suspended particle amounts are used as the emission rate of the dispersion model simulations and the dispersion characteristics of the suspended particles are analyzed.

• 한국해안해양공학회지
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• 제15권1호
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• pp.39-50
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• 2003

시화호 북측확장단지 조성을 위하여 반월천과 동화천이 유입되는 상류에서 호안 축조 공사가 진행되는 경우 침적된 오열도가 실한 이 지역에서 저니토가 급격하게 교란될 때 시화호 수질에 미치는 영향을 평가하기 위하여 본 연구를 수행하였다. 3차원 수동역학 모델인 TIDE3D를 수질모델인 CE-QUAL-ICM과 결합하고 4개의 $\sigma$층을 사용하여 수체와 저질사이의 상호작용과 층별 변화를 모의하였다. 1년 이상의 장기적인 수질모의결과, 교란된 지점 인근에서는 저층에만 수질의 악화철상이 나타나고 시화호의 형상 및 외부 하천 유입의 복합적인 특성 상 약 5km를 지나면서 저질 교란의 영향이 표층에 나타난다. 현재의 상황에서는 겨울과 봄에 상류 오염유입이 많아서 COD와 TP수질이 좋지 않으나 이에 비해 저질의 교란으로 야기되는 수질 변화는 여름과 가을에 크게 저하되는 것으로 나타나 현존 상태와 반전된 결과를 제시한다. 선행연구(서 등, 2002)에서 취하였던 격자망보다 배정밀도로 상세화 하여 150m${\times}$150m의 격자에서 수치실험 한 결과는 계산시간의 증대를 유발하지만, 격자의존도가 수치해에 미치는 영향이 있는 것으로 판단되며 특히 유동이 배수갑문 인근의 영역에서 신을 통과하는 유량의 차이를 줄여 만족스러운 결과를 제공한다.

• 한국토양비료학회지
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• 제44권5호
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• pp.667-673
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• 2011

우리나라 밭은 대부분 산지를 개간하여 조성한 경사 밭으로 작물이 재배되는 여름철 집중강우에 의해 많은 양의 토양이 유실된다. 특히 경사 밭 전면경운에 의한 토양 교란은 무의 발아, 생육초기 단계로 쏟아지는 강우에 표토가 직접 노출되어 토양유실 위험이 가중되고 있다. 본 연구에서는 고랭지 무 재배의 경우 토양피복방법 개선에 의한 토양유실 저감기술을 개발하고자 수행하였다. 토양피복 방법으로 호밀 예취피복, 호밀 초생피복, 흑색비닐멀칭 등 8 처리를 두었으며, 경사 17%내외 무저라이시메타에서 유거수 및 토양유출 특성과 무 생육특성을 평가하였다. 시험결과 호밀예취피복을 포함한 토양피복처리는 유거수 유출량에 있어 ha당 관행 $2,994m^3$인 반면, $773{\sim}2,325m^3$이 유거되어 관행보다 26~78% 수준으로 유거수 량이 감소하였다. 이와 같은 결과는 토양유실량에도 영향을 미쳐 관행 처리구가 ha당 68.2톤인 반면, 호밀예취피복을 포함한 피복처리구는 0.3~16.1톤으로 관행 대비 76~99%에 해당하는 토양유실 경감 효과가 있는 것으로 평가되었다. 무 수확기 수량 구성요소인 근중은 관행의 경우 ha당 92.5톤 수준을 보였는데, 호밀 초생피복은 40.1톤, 벌개미취 초생피복은 46.1톤, 곰취 초생피복은 78.5톤 수준으로 낮은 경향을 보였다. 반면, 호밀 예취피복은 92.9톤, 들묵새 초생피복은 102.6톤, 흑색비닐멀칭은 109.8톤으로 관행과 비슷하거나 오히려 증수되는 결과를 보였다. 본 연구 결과 호밀 예취피복 및 들묵새 초생피복은 무 수량에 는 영향을 미치지 않으면서 토양유실 경감효과가 매우 높아 경사 밭 토양보전기술로 유용하게 적용 되리라 판단된다.