• Title/Summary/Keyword: Precipitation Behavior

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A Study on Ion Distribution and Behavior of Acidrain in Mokpo and Yeochon Area (목포, 여천지역 강수의 무기이온 성분농도와 거동에 관한 연구)

  • 오길영;양수인;이완진
    • Journal of Korean Society for Atmospheric Environment
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    • v.15 no.4
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    • pp.385-392
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    • 1999
  • This study was carried out to investigate the constituents of inorganic ions of precipitation in Mokpo and Yeochon area from Jan. 1996 to Dec. 1997. The volume-weighted mean pH of precipitation was 5.7(4.8~7.8) at Mokpo, and 5.6(5.1~7.4) at Yeochon area, respectively. The non-seasalt(nss) anion concentrations were found in order of $nss-SO^{2-}_4>NO^-_3>nss-Cl^-$ at two areas. The portion of $nss-SO^{2-}_4;and;NO^-_3$ was 71~84% out of anions. The the non-seasalt cation concentrations were found in order of $NH^+_4>nss-Ca^{2-}>nss-Mg^{2+}>nss-K^-$ at two areas. The portion of $NH^+_4;and; nss-Ca^{2+}$ was 85~92% out cations. Compared regionally the year concentraton of $nss-SO^{2-}_4$, the result of Yeochon was 3 times higher than that of Mokpo in 1996, while the results of two regions were almost similar in 1997. The reason was that Yeochon was restricted area of the use of 0.5% sulfur B-C oil, controlled air pollution emission area, controlled semitotal amounts of air pollution emission area and partial operating of factories in 1997. There were no ions having high correlation with $H^+,;but;nss-SO^{2-}_4,;NO^-_3,;NH^+_4;and;nss-Ca^{2+}$ showed high correlation coefficient each other. It seems that these ions have little correlation with $H^+$ because they are washed out on binding state. Factor analysis showed that the first factor was complicated factor containing anthropogenic and soil resource, the second factor was sea-salt resource and the third factor was independent behavior of hydrogen at Mokpo. While, the first factor was complicated factor containing anthropogenic and sea-salt resource, the second factor was $Ca(NO_3)_2$ salt and the third factor was $NH^+_4;and;SO^{2-}_4$ synergied by resource and combination at Yeochon.

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The Stochastic Behavior of Soil Water and the Impact of Climate Change on Soil Water (토양수분의 추계학적 거동과 기후변화가 미치는 영향)

  • Han, Su-Hee;Ahn, Jae-Hyun;Kim, Sang-Dan
    • Journal of Korea Water Resources Association
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    • v.42 no.6
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    • pp.433-443
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    • 2009
  • For the better understanding of the temporal characteristics of soil water, this study is to suggest a stochastic soil water model and to apply it for impact assessment of climate change. The loss function is divided into 3 stages for more specified comprehension of the probabilistic behavior of soil water, and especially, the soil water model considering the stochastic characteristics of precipitation is developed in order to consider the variation of climatic factors. The simulation result of soil water model confirms that the proposed soil water model can re-generate the observation properly, and it also proves that the soil water behaves with consistent cycle based on the precipitation pattern. Moreover, with the simulation results with a climate change scenario, it can be predicted that the future soil water will have higher variations than present soil water.

Effect of W Substitution on the Precipitation Behavior of χ and σ Phase in Super Duplex Stainless Steels (슈퍼 2상 스테인리스강에서 χ와 σ상의 석출거동에 미치는 W치환의 영향)

  • Han, Huyn-Sung;Kim, Seong-Hwi;Kang, Chang-Yong
    • Korean Journal of Materials Research
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    • v.26 no.4
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    • pp.200-206
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    • 2016
  • This study was carried out to investigate the effect of W substitution on the precipitation behavior of ${\chi}$ and ${\sigma}$ phases in super duplex stainless steel. The ${\chi}$ phase was precipitated at the interface of ferrite / austenite phases and inside the ferrite phase at the initial stage of aging. With an increase in the aging time, the volume fraction of the ${\chi}$ phase increased, and then decreased with the transformation from the ${\chi}$ phase to the ${\sigma}$ phase. The ${\sigma}$ phase was precipitated later than the ${\chi}$ phase, and the volume fraction of x phase increased with the increase in the aging time. The ferrite phase was decomposed into the new austenite (${\gamma}2$) and ${\sigma}$ phases by aging treatment. The decomposition of the ferrite phase into the ${\gamma}2$ and ${\sigma}$ phases was retarded by W substitution for Mo. The volume fraction of the ${\chi}$ phase increased and that of the ${\sigma}$ phase decreased due to W substitution. The ${\chi}$ and ${\sigma}$ phases were intermetallic compounds, which had lower nickel concentration, and higher chromium, molybdenum, and tungsten concentrations. The ${\chi}$ phase has higher molybdenum and tungsten concentrations than those of the ${\sigma}$ phase. The amounts of chromium and nickel in the ${\chi}$ and ${\sigma}$ phases did not change, but these phases have higher concentrations of molybdenum and tungsten due to W substitution for Mo.

Dissolution Behavior of Plagioclase in HCl and KOH Solutions (염산과 수산화칼슘 수용액과의 반응에 의한 사장석의 용해 거동)

  • 현성필;김수진
    • Journal of the Mineralogical Society of Korea
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    • v.9 no.2
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    • pp.71-81
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    • 1996
  • Dissolution experiments were conducted to understand chemical nature of weathering of anorthosite from the Hadong area. Anorthosite and plagioclase from it were reacted with HCl or KOH solutions under various conditions concerning such as grain size, initial pH of solutions, and shaking Average composition of plagioclase used in the experiment was Na0.32Ca0.71Al1.71Si2.28O8.Under acidic conditions, solution pH increases rapidly in the initial stage and then gradually to reach palteau. Shaking agitates the reaction rate in the initial stage but does not affect after the system reached steady state. Ca and si concentrations show rapid increase and then gradual increase. Al concentration increases rapidly in the early stage and then decreases. Later decrease was interpreted as the precipitation of an Al-bearing material. Different dissolution rates of different constituents of plagioclase together the with precipitation of al-bearing material might be responsible for the non-stoichiometric dissolution of plagioclase.X-ray diffraction analyses on anorthosite before and after dissolution experiment show dissolution rates differ with different lattice planes of plagioclase. It suggests the crystallographic control on dissolution reaction. X-ray photoelectron spectroscopic result shows that the average composition of plagioclase surface reacted with HCL of initial pH 1.97 for 2000 hours is Na0.20Ca0.26Al1.7Si2.3O8. It means that Na- and Ca-depleted H-feldspar is developed without Al-depleted layer on the surface of plagioclase by reaction with HCl and that dissolution reaction takes place sparsely on the surface of plagioclase. Al and Si are dissolved preferentially over Ca from anorthosite powder in KHO solution. Reaction of acid-reacted anorthosite with KOH solution shows the same Si dissolution behavior as in the fresh anorthosite. This indicates that the Al-depleted and Si-enriched layer does not build up on the acid-reacted surface.

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A Study on the Aging Behavior of a Mg-8.5Li-4.5Al alloy by Differential Scanning Calorimetry (열분석법에 의한 Mg-8.5Li-4.5Al합금의 시효거동 연구)

  • Kim, Y.W.;Hwang, Y.H.;Park, T.W.;Kim, D.H.;Hong, C.P.
    • Journal of the Korean Society for Heat Treatment
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    • v.10 no.4
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    • pp.255-265
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    • 1997
  • Precipitation and strengthening mechanisms in squeeze cast Mg-8.5wt%Li-4.5wt%Al have been investigated by differential scanning calorimetry(DSC), scanning electron microscopy(SEM), in-situ and ex-situ X-ray diffraction analysis and hardness measurement. Special emphasis was placed on the investigation of the precipitation behavior by the DSC technique. Microstructural and calorimetric analysis showed that ${\theta}$ and ${\delta}$ precipitates in the b.c.c. ${\beta}$ phase matrix, forming two exothermic peaks at the temperature ranges of $130^{\circ}C{\sim}180^{\circ}C$ and $236^{\circ}C{\sim}280^{\circ}C$. ${\theta}$ and ${\delta}$ dissolve into the matrix forming an endothermic peak at the temperature range of $280^{\circ}C{\sim}352^{\circ}C$. The as-cast microstructure consists of ${\alpha}$, ${\beta}$ and ${\delta}$. Peak strength was obtained after aging for 1 hour at $50^{\circ}C$. The aging time required for the peak strength decreased as the aging temperature increases. The hardness decrease during overaging was due to the coarsening of ${\theta}$ precipitates. Microhardness measurement showed that variation of the hardness of ${\beta}$ matrix was more pronounced than that of the ${\alpha}$ phase, indicating that the ${\beta}$ phase is more responsible for the strengthening of the Mg-8.5wt%Li-4.5wt%Al alloy.

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Chaotic Analysis of Water Balance Equation (물수지 방정식의 카오스적 분석)

  • 이재수
    • Water for future
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    • v.27 no.3
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    • pp.45-54
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    • 1994
  • Basic theory of fractal dimension is introduced and performed for the generated time series using the water balance model. The water balance equation over a large area is analyzed at seasonal time scales. In the generation and modification of mesoscale circulation local recycling of precipitation and dynamic effects of soil moisture are explicitly included. Time delay is incorporated in the analysis. Depending on the parameter values, the system showed different senarios in the evolution such as fixed point, limit cycle, and chaotic types of behavior. The stochastic behavior of the generated time series is due to deterministic chaos which arises from a nonlinear dynamic system with a limited number of equations whose trajectories are highly sensitive to initial conditions. The presence of noise arose from the characterization of the incoming precipitation, destroys the organized structure of the attractor. The existence of the attractor although noise is present is very important to the short-term prediction of the evolution. The implications of this nonlinear dynamics are important for the interpretation and modeling of hydrologic records and phenomena.

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The Oxidation of Chalcopyrite and Geochemical Behavior of Heavy Metals in the Manjang Cu Mine (만장광산에서 산출되는 황동석의 산화과정과 중금속 거동 특성)

  • 이평구;이인경;최상훈;김지수
    • Economic and Environmental Geology
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    • v.37 no.3
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    • pp.291-301
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    • 2004
  • In order to charaterize weathering of chalcopyrite and behavior of dissolved metal ions in waste rocks from Manjang Cu mine, mineralogical studies such as refractive microscope, XRD and SEM/EDS analyses carried out. The weathering was mainly occurred in fractures and edge of the chalcopyrite within the mine waste rocks. The weathering process can be seen to reflect four stages based on the weathering degree of chalcopyrite. The main secondary minerals are goethite, covellite, azurite, malachite and brochantite. Dissolved Cu and As were mainly adsorbed Fe-hydroxide. Poorly crystalline Fe-oxide contains relatively high As contents. In oxdizing condition, the weathering of chalcopyrite mainly occurs along the fracture, while the replacement of chalcopyrite observed mainly in the grain and produced covellite and brochantite. The dissolved metals (Cu, Fe, As) in waste rocks from the abandoned Manjang mine area could attenuate naturally by precipitation, adsorption and replacement reaction.

A Neural Network for Long-Term Forecast of Regional Precipitation (지역별 중장기 강수량 예측을 위한 신경망 기법)

  • Kim, Ho-Joon;Paek, Hee-Jeong;Kwon, Won-Tae
    • Journal of the Korean Association of Geographic Information Studies
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    • v.2 no.2
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    • pp.69-78
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    • 1999
  • In this paper, a neural network approach to forecast Korean regional precipitation is presented. We first analyze the characteristics of the conventional models for time series prediction, and then propose a new model and its learning method for the precipitation forecast. The proposed model is a layered network in which the outputs of a layer are buffered within a given period time and then fed fully connected to the upper layer. This study adopted the dual connections between two layers for the model. The network behavior and learning algorithm for the model are also described. The dual connection structure plays the role of the bias of the ordinary Multi-Layer Perceptron(MLP), and reflects the relationships among the features effectively. From these advantageous features, the model provides the learning efficiency in comparison with the FIR network, which is the most popular model for time series prediction. We have applied the model to the monthly and seasonal forecast of precipitation. The precipitation data and SST(Sea Surface Temperature) data for several decades are used as the learning pattern for the neural network predictor. The experimental results have shown the validity of the proposed model.

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Chemical Composition of Rainwater in Chonju-city, Korea (전주시에서 채수된 강수의 화학적 조성)

  • 나춘기;정재일
    • Journal of Korean Society for Atmospheric Environment
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    • v.13 no.5
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    • pp.371-381
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    • 1997
  • Precipitation sampls were collected in Chonju-city during October 1994 to September 1995 and were analysed for major ions (N $a^{+}$, $K^{+}$, $Ca^{2+}$, $Mg^{2+}$, C $l^{[-10]}$ , NO/$_3$, S $O_4$$^{2-}$) and trace metals (Al, Cd, Ni, Pb, Sr, Zn) in addition to pH, in order to understand the chemical characteristics of acid rain and to estimate the origin of the determined ions. Most rain showed a neutral or alkaline character, and only 35% had a pH lower than 5.6. S $O_4$$^{2-}$ and N $O_3$$^{[-10]}$ are identified as the primary contributors to precipitation acidity in this region. Neutralization of precipitation acidity occurs as a result of the dissolution of alkaline compounds containing $Ca^{2+}$, $Mg^{2+}$ and $K^{+}$. S $O_4$$^{2-}$ and N $O_3$$^{[-10]}$ precipitation concentrations exhibit a seasonal pattern in which higher concentrations are observed during spring months and lower concentrations during summer months. However, the seasonal behavior of $H^{+}$ concentrations differs from this pattern, in that the highest concentrations occur during autumn months, owing to the different influence of neutralization processes. In all rain, S $O_4$$^{2-}$ concentration exceeded NO/$_3$$^{[-10]}$ concentration. The contribution of maritime sources to the total S $O_4$$^{2-}$ concentration was very low or negligible. For rain strongly affacted by yellow sand, $Ca^{2+}$, $Mg^{2+}$ and $K^{+}$ ions show a sharp increase in concentration, reflecting the increased amount of dust and soil suspended in atmosphere. At the same time, S $O_4$$^{2-}$ and N $O_3$$^{[-10]}$ concentrations are at their highest levels while $H^{+}$ values are not comparably elevated, presumably beacause much of the acidity has been neutralized by alkaline substances. The seasonal variance of trace metal concentrations in rainwater is similar to that of major cations. The annual wet flux of acidic pollutants and trace metals wat calculated to be as follows: N $O_3$$^{[-10]}$ ; 2.32 g/$m^2$, S $O_4$$^{2-}$, 5.34 g/$m^2$, Al; 6.30 mg/$m^2$, Cd; 0.62 mg/$m^2$, Ni; 4.08 mg/$m^2$, Pb: 9.76 mg/$m^2$, Sr; 5.94 mg/$m^2$, Zn; 111 mg/$m^2$./$m^2$.

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Study on Paraffin Wax Precipitation using Model Oils (모델오일을 이용한 파라핀 왁스의 침전 연구)

  • Oh, Kyeong-Seok
    • Journal of the Korean Applied Science and Technology
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    • v.34 no.3
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    • pp.495-503
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    • 2017
  • Wax components can be precipitated when surrounding temperature decreases below wax precipitation temperature (WAT). WAT as well as pour point are important characteristics to evaluate the behavior of waxy oils. In this study, qualitative and quantitative evaluations of waxes in waxy model oils were presented after determining WAT and pour point. In case of anhydrous waxy model oils, ASTM D2500 may be most useful to determine WAT because of the transparent nature of model oils. With same apparatus, ASTM D97 is also applicable to determine the pour point of waxy oils in a serial determination. In case of emulsified model oils, however, it is difficult to measure WAT because of its opaque nature. This study employed FTIR spectroscopy to determine wax precipitation temperature and discussed the effect of emulsion state regarding the values of WAT. Further study would be needed to conclude the effect of water contents to WAT values in case of emulsified waxy oil.