• Title/Summary/Keyword: $SO_2$ inflow

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POM/MICOM Inter-Comparison in Modeling the East Sea Circulation

  • Kim, Kuk-Jin;Seung, Young-Ho;Suk, Moon-Sik
    • Ocean and Polar Research
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    • v.23 no.2
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    • pp.161-172
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    • 2001
  • A model-to-model comparison is attempted between Princeton Ocean Model (POM) and Miami Isopycnic Coordinate Ocean Model (MICOM) as a first step to extend our knowledge of models' performances in studying the East Sea circulation. The two models have fundamentally different numerical schemes and boundary conditions imposed on these models are not exactly the same each other. This study indicates that MICOM has a critical weak point in that it does not reproduce the shallow surface currents properly while it handles the thermohaline processes and associated movements of intermediate and deep waters efficiently. It is suggested that the mixed layer scheme needs to be modified so that it can match with inflow boundary conditions in order to reproduce the surface currents properly in MICOM. POM reproduces the surface current pattern better than MICOM, although the surface currents in POM appear to undergo the unrealistic seasonal variation and have exaggeratedly large vertical scale. These defects seem to arise during the process of adapting POM to the East Sea, and removing these defects is left as a future task.

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Proper Conditions of Structure to Prevent Eddy Creation in Cooling Water Intake Canal of Stream Power Plant (화력발전소 냉각 취수로내의 와류발생 방지를 위한 구조물의 적정조건검토)

  • 조진훈;천만복
    • Proceedings of the Korean Society of Agricultural Engineers Conference
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    • 1999.10c
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    • pp.465-472
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    • 1999
  • Hydraulic model tests are performed to find economical and hdrqulically stable design of cooling water intake channel of steam power plant. The result of tests show that the standard distributiion of y-components in the chamber of CWP(circulating Water Pump) are recommended below 3.5 to maintain hydraulic stability, so that this value is considered as the design criteria. Common basin is necessary to improve the hydraulic stability of inflow, however the longer basin does not always improve the hydraulic stability , and the optimal length of basin can be found in some range. From the results the flow stability maintained the best condition when the length of basin is 7.2m. Beside the standard tests the auxiliary tests like edge , baffle, trapezoidal section and increase of pump capacity are carried out based on the optimal condition foudn in the standard tests. From the series of tests the economical and hydraulically stable design of intake channel was proposed.

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Seasonal Variation of Surface Water Quality in a Catchment Contaminated by $NO_3-N$ (질산성 질소로 오염된 소유역 하천 수질의 계절 변화)

  • Kim Youn-Tae;Woo Nam-Chil;Lee Kwang-Sik;Song Yun-Goo
    • Journal of Soil and Groundwater Environment
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    • v.10 no.2
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    • pp.20-27
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    • 2005
  • The seasonal variation of water quality was studied in the Hwabongcheon. It runs though a small catchment where shallow groundwater was contaminated with $NO_3-N$ by intensive livestock facilities. A direct inflow of animal waste and incoming of contaminated groundwater affected its water quality. In the dry season, an important factor of water quality in the Hwabongcheon was direct inflow of animal waste. In the wet season, concentrations of $NO_3-N$ in the Hwabongcheon were elevated in spite of being diluted by precipitation. It could be explained by the effect of increased incoming of contaminated groundwater and showed by oxygen and hydrogen isotope values. $NO_3-N$ concentration in the Cheongmicheon was lower than that in the Hwabongcheon, so it increased next a junction. This effect was intense in wet season because $NO_3-N$ concentration in the Hwabongcheon was high.

Hydrological Stability Analysis of the Existing Soyanggang Multipurpose Dam

  • Ko, Seok-Ku;Shin, Yong-Lo
    • Korean Journal of Hydrosciences
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    • v.7
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    • pp.37-49
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    • 1996
  • This study aims at suggesting an alternative to improve flood controling capacity according to the cument design criteria for the existing Soyanggang Multi-purpose Dam which was constructed 20 years ago as the largest dam in Korea. The peak inflow of the adopted probable maximum flood (PMF) at the time of construction was 13,500 $m^3$/s. However, the newly estimated peak inflow of the PMF is 18,000 $m^3$/s which is 1.34 times bigger than the original one. This is considered to be due to the accumulation of the reliable flood and storm event records after construction, and due to the increasing tendency of the local flood peaks according to the influence of world-wide weather change. The new estimation of the probable maximum precipitation (PMP) was based on the hydro-meteorological method suggested by the guideline of the World Meteorological Organization (WMO). The unit hydrograph which was applied for the estimation of PMF was derived through linear programming algorithm by minimizing the sum of absolute deviations of the calculated and recorded flood hydrographs. In order to adopt the newly estimated PMF as a design flood, following four alternatives were compared : (1) allocation of more flood control space by lowering the normal high water level, (2) construction of a new spillway in addition to the existing spillway, (3) construction of a new dam which has relevant flood control storage at the upstream of the Soyanggang dam, (4) raising the existing dam crest. The preliminary evaluation of these alternatives resulted in that the second alternative is most economic and feasible. So as to stably cope with the newly estimated PMF by meeting all the current functions of the multipurpose dam, a detailed study of an additional spillway tunnel has to be followed.

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Technology to reduce water ingress for TBM cutterhead intervention

  • Ham, Soo-Kwon;kim, Beom-Ju;Lee, Seok-Won
    • Geomechanics and Engineering
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    • v.29 no.3
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    • pp.321-329
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    • 2022
  • Tunnel site where high water pressure is applied, such as subsea tunnel, generally selects the shield TBM (Tunnel Boring Machine) to maintain the tunnel excavation face. The shield TBM has cutters installed, and the cutters wear out during the process of excavation, so it should be checked and replaced regularly. This is called CHI (Cutterhead Intervention). The conventional CHI under high water pressure is very disadvantageous in terms of safety and economics because humans perform work in response to high water pressure and huge water inflow in the chamber. To overcome this disadvantage, this study proposes a new method to dramatically reduce water pressure and water ingress by injecting an appropriate grout solution into the front of the tunnel face through the shield TBM chamber, called New Face Grouting Method (NFGM). The tunnel model tests were performed to determine the characteristics, injection volume, and curing time of grout solution to be applied to the NFGM. Model test apparatus was composed of a pressure soil tank, a model shield TBM, a grout tank, and an air compressor to measure the amount of water inflow into the chamber. The model tests were conducted by changing the injection amount of the grout solution, the curing time after the grout injection, and the water/cement ratio of grout solution. From an economic point of view, the results showed that the injection volume of 1.0 L, curing time of 6 hours, and water/cement ratio of the grout solution between 1.5 and 2.0 are the most economical. It can be concluded that this study has presented a method to economically perform the CHI under the high water pressure.

A Study on the Performance Evaluation of Recirculation System for Individual Hot Water Supply System in Residential Buildings (주거건물의 개별급탕방식 환탕배관 적용에 따른 급탕성능 평가에 관한 연구)

  • Cha, Min-Chul;Yeo, Myoung-Souk;Seok, Ho-Tae
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.19 no.12
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    • pp.857-864
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    • 2007
  • In the current residential building, hot water supply system consumes the second largest energy in order to make the thermal comport condition of residential space. The more residential environment improves the more the demand for hot water and water consumption is increasing gradually. So this study examines the possibility of applying the recirculation for individual hot water supply system compared with the existing method for waiting time for hot water, wasted water and energy consumption. The results are as follows. (1) In case of recirculation system method the waiting time for hot water can be reduced up to $69\sim85%$ in spring and fall period and so dose up to $77\sim85%$ in winter period. (2) The total wasted water has a little change compared with the existing method which can make the total wasted water reduced about $77\sim86%$. (3) The efficiency of hot water supply system can be improved, if the method which blocks the inflow of cold water is applied, when return pump is operated to recirculate hot water in recirculation system.

Pollution Characteristics of Rainwater at Jeju Island during 2009~2010 (2009~2010년 제주지역 강우의 오염 특성 연구)

  • Kim, Ki-Ju;Bu, Jun-Oh;Kim, Won-Hyung;Lee, Yoon-Sang;Hyeon, Dong-Rim;Kang, Chang-Hee
    • Journal of Korean Society for Atmospheric Environment
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    • v.29 no.6
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    • pp.818-829
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    • 2013
  • The collection of rainwater samples was made at Jeju area during 2009~2010, and the major ionic species were analyzed. In the comparison of ion balance, conductivity, and acid fraction for the validation of analytical data, the correlation coefficients showed a good linear relationship within the range of 0.966~0.990. The volume-weighted mean pH and electric conductivity were 4.9 and $17.8{\mu}S/cm$, respectively, at the Jeju area. The volume-weighted mean concentrations of ionic species in rainwater were in the order of $Cl^-$ > $Na^+$ > $nss-SO_4{^{2-}}$ > $NH_4{^+}$ > $NO_3{^-}$ > $Mg^{2+}$ > $H^+$ > $nss-Ca^{2+}$ > $HCOO^-$ > $K^+$ > $PO_4{^{3-}}$ > $CH_3COO^-$ > $NO_2{^-}$ > $F^-$ > $HCO_3{^-}$ > $CH_3SO_3{^-}$. The ionic strength of rainwater was $0.26{\pm}0.21$ mM during the study period. The composition ratios of ionic species were such as 50.1% for the marine sources ($Na^+$, $Mg^{2+}$, $Cl^-$), 30.9% for the anthropogenic sources ($NH_4{^+}$, $nss-SO_4{^{2-}}$, $NO_3{^-}$), and 4.7% for the soil source ($nss-Ca^{2+}$), and 3.1% for organic acids ($HCOO^-$, $CH_3COO^-$). From the seasonal comparison, the concentrations of $NO_3{^-}$, $nss-Ca^{2+}$, and $nss-SO_4{^{2-}}$ increased in winter and spring seasons, indicating a reasonable possibility of long range transport from Asia continent. Especially, the acidifying contributions by major inorganic acids ($nss-SO_4{^{2-}}$ and $NO_3{^-}$) and organic acids ($HCOO^-$ and $CH_3COO^-$) were 87.6% and 12.4%, respectively. In comparison by sectional inflow pathway of air mass during the rainy sampling days, the concentrations of $nss-SO_4{^{2-}}$ and $NO_3{^-}$ were relatively high when the air mass was moved from the China continent into Jeju area.

Water Quality Modeling for Intake Station by 2-dimensional Advection-Dispersion Model (2차원 이송-확산 모형을 이용한 취수장 유입 수질 예측)

  • Kim, Jae-Dong;Kim, Ji-Hoon;Kim, Young-Do;Song, Chang-Geun;Seo, Il-Won
    • Journal of Korean Society of Water and Wastewater
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    • v.25 no.5
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    • pp.667-679
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    • 2011
  • In this study, the influences of pollutant from Dae-po Stream and So-gam Stream located at the downstream of Nak-dong River on the water quality at Mul-geum water intake station were analyzed using RAMS model. Field measurements of velocity by ADCP, and water quality distribution of BOD and TP by water sampling were carried out to present the input and verification data for numerical simulations. The comparison between RAM2 and ADCP measurement, which aimed for the analysis of 2-D velocity distribution around Mul-geum water intake station showed that two results matched well along the spanwise direction. The prediction of pollutant concentration by RAM4 agreed fairly well with the measured data except for the points nearby right banks in the vicinity of tributary pollutant source. Flushing effect by the increase of mainstream discharge in Nak-dong River was analyzed to provide the damage mitigation in preparation for the accidental water pollution. With increasing mainstream discharge, high velocity and increased water quantity induced increasing dilution effect, thereby decreasing the inflow pollutant concentration rapidly.

Hydrochemical Properties of the Onyang Hot Spring Waters (온양지역 온천수의 수리화학적 특성)

  • Yun, Uk;Cho, Byong Wook;Lee, Cholwoo
    • The Journal of Engineering Geology
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    • v.26 no.4
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    • pp.561-570
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    • 2016
  • For the investigation of hydrochemical changes in hot spring waters from the Onyang hot spring area, we analyzed water chemistry of 24 hot spring waters in 2011 and 2016. The results showed that there is no significant change in temperature and properties of the hot spring waters. The relationship of 2016 between temperature and $SiO_2$ and F reveals a positive trend ($r^2=0.60$, 0.47), and the relationship between temperature and Ca, Mg, Cl, $SO_4$, $HCO_3$, EC reveals a negative trend ($r^2=0.50$, 0.11, 0.50, 0.63, 0.23, 0.51). The relationship between temperature and pH is a positive trend, while the one between temperature and DO is a negative trend, indicating that the source is from deep groundwater. When plotted on Piper diagram, most of which are $Na-HCO_3$ but several hot waters are classified as the $Na(Ca)-HCO_3$, indicating inflow of shallow groundwater was occurred.

A Method of Evaluating Profitability and Risk of Multiple Investments Applying Internal Rate of Return

  • Mizumachi, Tadahiro
    • Industrial Engineering and Management Systems
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    • v.9 no.2
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    • pp.121-130
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    • 2010
  • In today's uncertain economic environment, economic risk is inherent in making large investments on manufacturing facilities. It is, therefore, practically meaningful to divide investment over multiple periods, reducing the risk of investment. Then, the cash-flow over the entire planning horizon would comprise positive inflow and negative outflow. In this case, in general, evaluation by internal rate of return (IRR) is not feasible, because multiple IRRs are involved. This paper deals with a problem of evaluating profitability, as well as risk, of investment alternatives made in multiple times of investment over the entire horizon. Typically, an additional investment is required after the initial one, for expanding manufacturing capacity or other reasons. The paper pays attention to a unit cash-flow over two periods, decomposing the total cash-flow into a series of unit cash-flow patterns. It is easy to evaluate profitability of a unit cash-flow by using IRR. The total cash-flow can be decomposed into the series of two types of unit cash-flows: an investment type one (negative-positive) and the borrowing type one (positive-negative). This paper, therefore, proposes a method in which only the borrowing type unit cash-flow is eliminated in the series by converting total cash-flow using capital interest rate. Then, a unique IRR can be obtained and the profitability is evaluated. Thus, the paper extends the method of IRR so that it may help decision making in complicated cash-flow pattern observed in practice.