• Journal of Biosystems Engineering
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• 제35권1호
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• pp.46-52
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• 2010

The temperature of root zone was known as an important factor for the growth of crops and reduction of energy in greenhouse. The purpose of this study was to design the apposite inflow of calories per the unit area by comparison of temperature in the warmed and non-warmed soil. The energy needed for soil warming about pipe length showed the change of temperature on inflow and outflow as $2^{\circ}C{\sim}3^{\circ}C$(average $2.5^{\circ}C$). Therefore, the inflow per the unit hour was 3,450, 57,5 kcal/$h{\cdot}m^2$ on soil heating respectively. The non-warmed soil temperature in greenhouse made a difference by depth and it was partially affected inner temperature under 15 cm, but it was not above 15 cm. The soil temperature would be raised over $5^{\circ}C$ than non-warmed soil to increase effect of soil warming. Therefore, the inflow per the unit area that should be provided was about 100 kcal/$h{\cdot}m^2$.

• 대한방사선기술학회지:방사선기술과학
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• 제25권1호
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• pp.55-62
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• 2002

Aneurysm-mimicking findings were frequently visualized due to hemodynamical causes of dephasing effects around area of A-com artery during magnetic resonance angiography(MRA) and these kind of phenomena have not been clearly known yet. We investigated the hemodynamical patterns of dephasing effect around area of the A-com artery that might be a cause of false intracranial aneurysms on MRA. For experimental study, We used hand-made silicon phantoms of the asymmetric A-com artery as like a bifurcation configuration. In a closed circulatory system with UHDC computer driven cardiac pump system. MRA and fast digital subfraction angiography(DSA) involved the use of these phantoms. Flow patterns were evaluated with axial and coronal imaging of MRA(2D-TOF, 3D-TOF) and DSA of Phantoms constructed from an automated closed-type circulatory system filled with glycerol solution [circulation fluid(glycerol:water = 1:1.4)]. These findings were then compared with those obtained from computational fluid dynamic(CFD) for inter-experimental correlation study. Imaging findings of MRA, DSA and CFD on inflow zone according to the following: a) MRA demonstrated high signal intensity zone as inflow zone on silicon phantom; b) Patterns of DSA were well matched with MRA on trajectory of inflow zone; and c) CFD were well matched with MRA on the pattern of main flow. Imaging findings of MRA. DSA and CFD on turbulent flow zone according to the following: a) MRA demonstrated hyposignal intensity zone at shoulder and axillar zone of main inflow; b) DSA delineated prominent vortex flow at the same area. The hemodynamical causes of signal defect, which could Induce the false aneurysm on MRA, turned out to be dephasing effects at axilla area of bifurcation from turbulent flow as the results of MRA, DSA and CFD.

• 한국주조공학회지
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• 제32권6호
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• pp.276-283
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• 2012

This study presents the results on the changes of crucible thermal conductivity and inflow of Ar, and constructed the mathematical model about heat transfer into furnace. As process variables, simulation model was designated thermal conductivity of crucible to $0.5W{\cdot}m^{-1}{\cdot}K^{-1}$, $1W{\cdot}m^{-1}{\cdot}K^{-1}$, $2W{\cdot}m^{-1}{\cdot}K^{-1}$, $4W{\cdot}m^{-1}{\cdot}K^{-1}$, and inflow rate of Ar to 15 L/min, 30 L/min, 60 L/min. Initial condition and boundary condition were set respectively in two terms of process. Each initial conditions were set up by the preceding simulation of heat and fluid flow. The primary goal is the application of unidirectional growth of Si ingot using the result. In the result of the change of heat conductivity of crucible, the higher thermal conductivity of crucible shows the shorter solidification time and the bigger temperature difference. And the flow patterns are changed with the inflow rate of Ar. Finally, we found that the lower crucible's thermal conductivity, the better crucible is at polycrystalline Si ingot growth. But in case of Ar inflow, it is hard to say about good condition. This data will be evaluated as useful reference used in allied study or process variable control of production facilities.

• Advances in environmental research
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• 제6권1호
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• pp.67-81
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• 2017

Mining activities play a significant role in environmental pollution by producing large amounts of tailings which comprise heavy metals. The impressive increase in mining activities in recent decades, due to their high influence on the industry of developing countries, duplicates the need for a substantial effort to develop and apply efficient measures of pollution control, mitigation, and abatement. In this study, our objective was to investigate the effect of simulation of the leachate, pH and inflow intensity of transport of $Pb^{2+}$, $Zn^{2+}$, and $Cd^{2+}$ through Lakan lead and zinc plant tailings, in Iran, and to evaluate the modeling efficiency by comparing the modeling results and the results obtained from previous column studies. We used the HP1 model and the PHREEQC database to simulate metals transport through a saturated soil column during a 15 day time period. The simulations assumed local equilibrium. As expected, a lower pH and inflow intensity increased metal transport. The retardation of heavy metals followed the order $Zn^{2+}$ > $Pb^{2+}$ > $Cd^{2+}$ and the removal concentrations of Cd, Pb, and Zn at the inflow intensity critical scenario, and Cd and Pb at inflow acidity critical scenario exceeded the allowable EPA and Iranian's 1053 standard thresholds. However, although the simulation results generally agreed well with the results of the column study, improvements are expected by using multi-dimensional models and a kinetic modeling approach for the reactions involved. The results of such investigations will be highly useful for designing preventative strategies to control reactive transport of hazardous metals and minimize their environmental effects.

• 상하수도학회지
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• 제33권3호
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• pp.177-190
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• 2019

The purpose of this study was to analyze the effects of sewerage facilities through I/I analysis by rainfall by selecting areas where storm overflow diverging chamber is remained due to the non-maintenance drainage equipment when the sewerage system was reconstructed as a separate sewer system. Research has shown that wet weather flow(WWF) increased from 106.2% to 154.8% compared to dry weather flow(DWF) in intercepting sewers, and that the WWF increased from 122.4% to 257.6% in comparison to DWF in storm overflow diverging chamber. As a result, owing to storm overflow diverging chamber of partially separate sewer system with untreated tributary of sewage treatment plant, rainfall-derived infiltration/inflow(RDII) has been analyzed 2.7 times higher than the areas without storm overflow diverging chamber. Meanwhile, infiltration quantity of this study area was relatively higher than that of other study areas. Therefore, it is necessary to reduce infiltration quantity through sewer pipe maintenance nearby river. Drainage equipment maintenance should be performed not to operate storm overflow diverging chamber in order to handle the appropriate sewage treatment plant capacity for rainfall because it is also expected that RDII due to rain will occur after maintenance. In conclusion, it is necessary to recognize aRDII(allowance of rainfall-derived infiltration/inflow) and to be reflected it on sewage treatment plant capacity because aRDII can occur even after maintenance to the complete separate sewer system.

• 해양환경안전학회지
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• 제18권6호
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• pp.610-616
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• 2012

세계는 지금 본격적인 에너지 기후시대로 도래했으며 녹색성장을 이끌 강력한 에너지 정책이 선진국가 진입의 초석으로 신재생에너지를 활용하여 미래의 에너지 자원으로 동력화하는 것이 21세기 에너지 수요를 충족시키는 개발 목표가 되고 있다. 최근 신재생에너지 개발의 필요성에 따라 해양에너지가 주목을 받고 있다. 해양에너지는 아직 개발되지 않은 가장 유망한 재생 및 청정에너지 자원 중 하나이다. 이에 따라 각 해역에 적합한 조류에너지 변환장치의 개발이 매우 필요하다. 본 연구에서는 조류발전용 터빈에 작용하는 유입각, 해저면 효과 및 공동현상 발생에 따른 효율의 변화를 후류유동특성을 통해 파악하였다. 계산 조건하에서 해저면 효과에 의한 효율저하는 크게 나타나지 않았고, 유입각은 10도 이상부터 효율 저하가 나타났고 45도에서는 출력계수가 7 % 낮게 계산되었다. 유입속도가 증가할수록 토크와 출력계수가 증가하였으나, 공동현상이 발생하는 3 m/s이상부터 오히려 출력저하가 나타났다. 또한 유동특성의 고찰을 통해 유입각이 크고 공동현상이 나타날수록 출력감소의 원인이 됨을 확인하였다.

• 한국습지학회지
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• 제11권3호
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• pp.37-47
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• 2009

본 연구지역은 전라남도에 위치한 고흥만 간척지 내 인공습지이며, 인공습지수와 주변 유입수의 수질특성을 파악하기 위해 2008년 3월 15일 및 2009년 1월 10일에 12개 지점에서 현장조사를 수행하였다. 수온, pH, DO, EC 및 salinity 항목은 현장측정 되었으며, 채수된 시료는 실내에서 TOC, Cl-, COD, TSS, T-P 및 T-N 성분을 분석하였다. 현장 관측된 5개 항목은 인공습지에 비해 유입지점들에서 높게 나타났으며, 이는 주변 농경 작지에서 유입되는 오염물질에 의한 것이다. 인공습지수와 유입수 내 농도비는 TOC 성분은 1월에, Cl 성분은 3 월에 더욱 높은 값을 보였다. COD 성분은 인공습지수에 대한 유입수의 농도비가 1.37배와 1.49배로서 유사하였다. 유입지점들에서 T-P와 T-N 성분의 평균값은 인공습지 내에서보다 3배 이상 높았으며, 인공습지의 자정능력에 의해 농도가 저감되었다. 본 연구지역의 인공습지에서는 유입수 내 Cl, T-P, T-N 성분의 정화효율이 높은 것으로 나타났다. Cl- 성분의 정화효율은 1차 관측 시 83%, 2차 관측 시 76% 이었으며, 이는 인공습지수에 의한 희석효과에 의한 것이다. T-P 성분의 정화효율은 67%(1차 관측)와 69%(2차 관측), T-N 성분은 100%(1차 관측)와 95%(2차 관측) 로서 매우 높았다. 본 연구에서 T-N의 정화효율이 비현실적으로 높은 것은 유입수의 양이 소량이어서 인공습지수 내에서는 질소 농도가 분석한계 이하로 나타났기 때문이다. 본 연구에서는 T-P 성분의 정화효율이 1월에, T-N 성분은 3월에 높게 나타나 생장기와 동절기의 영향에 의한 것으로 판단된다.

• 무역학회지
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• 제41권3호
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• pp.177-198
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• 2016

중국은 1979년부터 본격적으로 시장경제체제를 도입함으로써 급격한 경제성장을 이루었는데, 본고는 저임금과 중국정부의 적극적인 외자유치정책을 활용하기 위해 밀려들어온 외국인투자에 어떤 요인들이 영향을 미쳤는지를 검토하기 위해 1979년부터 2013년까지의 패널데이터를 이용해서 각 성·시의 고유한 특성까지 활용하는 실증분석을 시도한다. 실증분석을 위해 본고는 확률효과모형, 고정효과모형, Pooled OLS, 그리고 확률계수모형을 사용하는데, Pooled OLS와 확률계수모형의 결과는 본 연구의 분석결과와 비교를 위해서 제시된다. Hausman' test 결과 Random Effect Model보다는 Fixed Effect Model이 더 효율적인 분석결과를 제시하는 것으로 나타나 이를 근거로 중국정부에 대한 정책적 시사점을 제시한다. 분석결과는 FDI유입에 각 성·시의 지역소득수준, 자본량, 통신비는 긍정적인 영향을 미치고 고속도로는 부정적인 영향을 미치는 것으로 나타난다.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2004년도 Asia Display / IMID 04
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• pp.700-702
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• 2004

The dependence of environmental gases such as Ar, $O_2$ on the emission current from carbon nanotube emitters was examined in this study. Based on our experiments, the current density is decreased in single-wall carbon nanotubes (SWNTs), but is increased in multi-wall carbon nanotubes (MWNTs) as the vacuum level decreases from $10^{-7}$ Torr to $10^{-4}$ Torr by the inflow purging gases. The current density subsequently recovered as the vacuum level increased to $10^{-7}$ Torr when gas inflow stopped. From those results, we conclude that the MWNTs have completely different degradation characteristics in comparison to SWNTs excluding the effect of binder materials.

• 상하수도학회지
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• 제8권3호
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• pp.1-8
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• 1994

In the general process of design for aerobic digestion, the design for field plant of which inflow pattern is continuous inflow is performed using the results from lab scale batch reactor. However, the recent researchers reported that the general designs were performed as over-estimated, Therefore, in this study, laboratory batch experiments were carried out at $20^{\circ}C$ and pH 7.5 on the aerobic digestion of waste activated sludge at different solid levels. This treatise could consider the negligence about effective digestion periods the usage of VSS as solid concentration, and the effect of initial solid concentration of solid degration rate coefficient($k_d$) as reasons of the overestimated design, and showed the scheme of how to design for aerobic digestion from batch experiment.