• Ocean Systems Engineering
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• 제6권4호
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• pp.305-324
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• 2016

Wave load prediction at zero forward speed using finite depth Green function is a well-established method regularly used in the offshore and marine industry. The forward speed approximation in deep water condition, although with limitations, is also found to be quite useful for engineering applications. However, analysis of vessels with forward speed in finite water depth still requires efficient computing methods. In this paper, a method for analysis of wave induced forces and corresponding motion on freely floating three-dimensional bodies with low to moderate forward speed is presented. A finite depth Green function is developed and incorporated in a 3D frequency domain potential flow based tool to allow consideration of finite (or shallow) water depth conditions. First order forces and moments and mean second order forces and moments in six degree of freedom are obtained. The effect of hull flare angle in predicting added resistance is incorporated. This implementation provides the unique capability of predicting added resistance in finite water depth with flare angle effect using a Green function approach. The results are validated using a half immersed sphere and S-175 ship. Finally, the effect of finite depth on a tanker with forward speed is presented.

• 한국작물학회지
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• 제31권1호
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• pp.56-61
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• 1986

옥수수품종 (Dekalb XL 72B)과 대두품종 ( Willi -ams)의 발아와 묘신장을 두 온도, 세 토양수분 포텐셜 및 네 polyethylene glycol(PEG) 8,000 수준에서 측정하였다. 각 품종의 20처리종자를 0.2% Thiram에 처리하여 가비중 1.20으로 압축된 살균사양토에 2.0cm 깊이로 파종 분할구배치법 사반복으로 실시하였다. 1. PEG로 한 삼투처리는 고온에서나 저토양수분포텐셜 조건에서 효과가 거의 없었다. 2. 대두는 옥수수보다 높은 묘수분함량을 보였고 두 작물 모두 토양수분 포텐셜과 온도가 증가할수록 수분흡수가 증가되었다. 3. 옥수수의 묘장이 35$^{\circ}C$에서는 대두보다 길었으나 15$^{\circ}C$에서는 짧았다. 4. 옥수수의 건물중은 35$^{\circ}C$에서 감소되었고 대두의 건물중은 토양수분 포텐셜이 증가할수록 감소되었다.

• 반도체디스플레이기술학회지
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• 제4권4호
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• pp.13-17
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• 2005

The behavior of ozone in $NH_4OH$ was investigated to evaluate the solution as a cleaning chemical of the silicon wafer. The solubility of ozone in DI(Deionized) water increased as the oxygen flow-rate decreased and ozone generator power increased. Ozone in DI water showed solubility of 100 ppm or higher at room temperature. Ozone concentration was stabilized at the range of ${\pm}2ppm$ by controlling oxygen flow rate and ozone generator power. On the contrary, the solubility of ozone in $NH_4OH$ was very low and strongly depended on the concentration of $NH_4OH$ and pH. The redox potential of ozone was saturated within 10 minutes in DI water and decreased rapidly with the addition of $NH_4OH$. The behavior of ozone in $NH_4OH$ is well explained by redox potential calculation.

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2005년도 후기학술대회논문집
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• pp.23-24
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• 2005

This paper investigated the mechanical and electrochemical properties of Al alloys in a slow strain rate test under various potential conditions. In general, Al and Al alloys do not corrode on formation of a film that has resistance to corrosion in neutral solutions. In seawater, however, $Cl^-$ ions lead to the formation and destruction of a passive film. In a potentiostatic experiment, the current density after 1200 sec in the potential range of $-0.68{\sim}-1.5 V$ was low. Comparison of the maximum tensile strength, elongation, and time to fracture indicated that the optimum protection potential range was from -1.5 to -0.7 V(SSCE).

• 지구물리와물리탐사
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• 제7권1호
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• pp.41-44
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• 2004

Measurements of streaming potential can provide a means for the detection and quantification of contaminants in groundwater prior to remediation. However, laboratory determinations of specific electrolyte properties are required for an adequate analysis of the hydraulic gradient in complex situations. Data obtained for the King River in Tasmania confirm a linear relationship linking streaming potential data and hydraulic gradients. Laboratory samples at low concentration (0.001M KCl) indicate values in the range 20-80 mV/cm of water pressure, while for higher concentrations (0.01M KCl) values are less than 25 mV/cm. Similar ion concentrations are observed in the King River, consistent with field correlations indicating values for streaming potential close to 15 mV/cm. In-situ fluid samples are required for more detailed analysis of local anomalies that may be associated with variations in recharge and migration of contaminants.

• 한국환경과학회지
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• 제22권9호
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• pp.1153-1160
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• 2013

While a range of natural organic matter (NOM) types can generate high levels of disinfection by-products (DBPs) after chlorination, there is little understanding of which specific compounds act as precursors. Use of eight model compounds allows linking of explicit properties to treatability and DBP formation potential (DBPFP). The removal of model compounds by various treatment processes and their haloacetic acid formation potential (HAAFP) before and after treatment were recorded. The model compounds comprised a range of hydrophobic (HPO) and hydrophilic (HPI) neutral and anionic compounds. On the treatment processes, an ozone oxidation process was moderate for control of model compounds, while the HPO-neutral compound was most treatable with activated carbon process. Biodegradation was successful in removing amino acids, while coagulation and ion exchange process had little effect on neutral molecules. Although compared with the HPO compounds the HPI compounds had low HAAFP the ozone oxidation and biodegradation were capable of increasing their HAAFP. In situations where neutral or HPI molecules have high DBPFP additional treatments may be required to remove recalcitrant NOM and control DBPs.

• 토지주택연구
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• 제2권4호
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• pp.503-507
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• 2011

신도시 A에 저탄소 녹색 마을(약 40만$m^2$)을 개발하고자 한다. 저탄소 녹색 마을의 조성을 위해서는 수문 순환의 복원 또는 물순환의 복원은 필수적이다. 저탄소 녹색 마을의 자연계 물순환 복원을 위해 LID-분산형 빗물 관리 시설의 설치를 계획하였다. 물순환에 미치는 영향 분석은 저탄소 녹색마을 개발 이전과 개발 후, 그리고 LID 시설(빗물정원, 인공습지, 빗물이용시설 등)을 설치한 후의 조건에서 EPA에서 개발된 SWMM-LID 모델을 이용하여 수행하였다. 개발 전의 침투 영역의 특성, 개발 후의 상당한 녹지 공간 탓으로, 수문 순환을 복원하기 위한 LID 설치 계획은 뚜렷한 효과를 보여주지 않고 있다. 그러나 LID 시설 설치에 의한 물순환의 가능성을 볼 수는 있었다. 이는 본 연구에서 제시한 LID 시설의 설치 계획이 해당 개발 지역의 물순환을 위해서는 더 확대되어야 함을 의미한다.

• Membrane and Water Treatment
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• 제14권4호
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• pp.175-180
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• 2023

Mixed matrix membranes (MMMs) can be a promising alternative for the solution of dye removal from coloured effluents. Polymeric membranes are widely used due to their good film-forming ability, flexibility, separation properties, and cost. However, they have low mechanical, chemical, and thermal resistances. Moreover, the fouling of polymeric membranes is high because of their hydrophobic nature. Hence, there is an increasing interest in organic-inorganic hybrid membranes as a new-generation membrane material. It has been shown that carbon nanotubes have the potential to increase the material properties of polymers with their low density, high strength, hardness, and exceptional aspect ratio. In this work, carbon nanotubes blended MMMs were prepared and methyl orange removal efficiency of them was investigated. Compared to the bare membranes, MMMs showed not only increased hydrophilicity, water content, and pure water flux but also increased methyl orange rejection and flux recovery

• 한국작물학회:학술대회논문집
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• 한국작물학회 2018년도 춘계학술대회
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• pp.103-103
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• 2018

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2001년도 봄 학술발표회 논문집
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• pp.985-990
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• 2001

Chloride permeability of high strength concrete(HSC) was investigated using saltwater pending test and rapid chloride permeability test by electrical potential(ASTM C 1202). The lower water-cement ratio concrete showed the lower diffusion coefficient of chloride. The relationship between the diffusion coefficient of chloride and charge passed by the rapid chloride permeability test could be obtained. This relationship appears to be an effective method for evaluating chloride permeability of low water-cement HSC.