• Membrane and Water Treatment
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• v.13 no.5
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• pp.245-257
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• 2022

Water quality characteristics and their spatial variations in the Nakdong River were statistically analyzed by multivariate techniques including correlation analysis, CA, and FA/PCA based on water quality parameters for 17 sites over 2017-2019, yielding PI values for primary factors. Site 10 indicated the highest parameter concentrations, and results of pearson's correlation analysis suggest that non-biodegradable organic matter had been distributed on the site. Five clusters were identified in order of descending pollution levels: I (Ib > Ia) > II (IIa > IIb) > III. Spatial variations started from sub-cluster Ib in which Daegu city and Geumho-river are joined. T-P, PO4-P, SS, COD, and TOC corresponded to VF 1 and 2, which were found to be principal components with strong influence on water quality. Sub-cluster Ib was strongly influenced by NO3-N and T-N compared to other clusters. According to the PIs, water quality pollution deteriorated due to non-biodegradable organic matter, nitrogen- and phosphorus-based nutrient salts in the middle and lower reaches, illustrating worsening water pollution due to inflows of anthropogenic sources on the Geumho-river, i.e., sewage and wastewater, discharged from Site 10, at which there is a concentration of urban, agricultural, and industrial areas.

• The Journal of Asian Finance, Economics and Business
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• v.8 no.9
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• pp.11-22
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• 2021

This study investigates the long-run relationship between the de jure economic, political, and social globalization and foreign direct investments in the Gulf Cooperation Council (GCC) to establish whether policies that foster trade and investment relations among geographical entities can help revive the GCC countries from the prevailing economic debacles of the COVID-19 pandemic. This study is driven by the GCC's quest to fully overcome the economic challenges occasioned by the outbreak of the global pandemic and position itself as the most potent regional economic bloc in the Middle East and North Africa (MENA) region. The study employs the panel data of the six GCC countries of Bahrain, United Arab Emirates, Kuwait, Qatar, Oman, and Saudi Arabia from 1971 to 2017. The findings of the panel fully modified ordinary least square regression estimation show that the de jure economic and social globalization have a significant positive impact on the region's foreign direct investment inflows. The impact of the de jure political globalization on foreign direct investment is statistically significant but negatively signed. Based on the preceding findings, we offer some holistic policy recommendations to the GCC region as recipes for timely recovery from the economic impact of COVID-19 and beyond.

• Proceedings of the Korea Water Resources Association Conference
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• 2021.06a
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• pp.172-172
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• 2021

주된 물관리 시설의 신뢰성 있는 운영 계획의 수립을 위하여 충분한 길이의 유입량을 확보하는 것은 중요하나 현실적으로 제한된 관측 자료만 존재한다. 본 연구에서는 충분한 길이의 유입량을 생성하기 위하여 유입량의 모의 방법론을 제안하고자 한다. 제안하는 모형은 크게 3가지의 방법론을 기반으로 한다. 첫 번째는 연 유입량과 월 유입량의 생성단계로 Wavelet 기반으로 Autoregressive-moving-average(ARMA)을 적용할 것이다. 다음으로 일 유입량의 생성에 있어서 과거 관측값을 기반으로 한 Z-Score-based jittering 방법론을 적용할 것이다. 이렇게 각각 생성된 연 유입량, 월 유입량 그리고 일 유입량을 K-Nearest Nedighbors (K-NN) 방법론을 이용하여 최종 유입량을 결정하고자 한다. 생성된 유입량의 유용성을 판단하기 위하여 본 연구에서는 단기와 장기에서의 시계열의 지속성을 허스트 지수와 상관계수를 사용하여 검증할 것이며 이를 과거 관측치와 비교하고자 한다. 또한 각각의 연, 월, 일별의 기준으로 주요 통계치인 평균과 표준편차를 과거 관측 시계열의 통계치와 비교하여 그 유용성을 판단할 것이다.

• International conference on construction engineering and project management
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• 2013.01a
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• pp.141-144
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• 2013

This paper presents a system called a Cash-flow based Construction Schedule Optimization system(CfSO). The existing CPM effectively handles schedule and cost management. However, funding strategy should be considered to obtain maximum profit and to progress a project favorably. One of measures is to coordinate the contract terms between owner and subcontractors (or suppliers). Contractor may decrease the interest cost attributed to project financing by adjusting the timing of cash-inflows and cash-outflows. It is an excellent method maximizing profits. This paper presents a method to estimate the amount of a cash-flow occurred periodically by integrating the terms of contract into scheduling. The proposed method is implemented as a system prototype in Microsoft Excel. This system provides a user an automated tool that identifies an optimal schedule that secures maximum profit by adjusting start and finish times of non-critical activities' free-floats without affecting on the project completion time. This system supports a project manager to establish an optimum project schedule and identifies profitable contractual conditions against to a construction owner.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.14 no.2
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• pp.317-324
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• 1994

The circulation of Lake Paldang is analysed numerically as an ultimate goal to develop a vehicle predicting the dispersion and concentration of pollutants and sediment flowed into the lake. In finite difference formulation of 2-D depth averaged governing equations. Abbott's 3-time level scheme is employed and for nonlinear terms time centering iteration technique in time and space is used. Model parameters for shear stresses and eddy diffusivities are determined through measured data in and near the lake. Predicted velocities for steady flow are shown to be close to the measured velocities and further improved by taking into account of wind effect. This indicates that the wind effect is needed for proper circulation analysis and it calls for the inclusion of the wind effect. Simulated results of unsteady flow caused by flood inflows and release through Paldang dam are found to characterize the flow features quite well as expected. This implies that the developed model can be used as a tool to analysing the circulation in the lake.

• Journal of Korea Water Resources Association
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• v.50 no.4
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• pp.263-275
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• 2017

Integrated numerical approaches with physically-based conceptualization are required for accurate urban inundation simulation. In this study, we described, applied and analyzed an integrated 1-dimensional (1D) sewerage system and 2-dimensional (2D) surface flow model, which was suggested by Lee et al. (2015). This model was developed based on dual-drainage concept, and uses storm drains as an discharge exchange spot rather than manholes so that interaction phenomena between surface flow and sewer pipe flow are physically reproduced. In addition, the building block concept which prevents inflows from outside structures is applied in order to consider building effects. The capability of the model is demonstrated via reproducing the past flooding event at the Sadang-cheon River catchment, Seoul, South Korea. The results show the plausible causes of the inundation could be analysed in detail by integrated 1D-2D modeling.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.15 no.4
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• pp.259-268
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• 2003

The damage of water quality like red tide occurs every year inspite of the total load regulation of pollutant inflows from land such as COD, phosphorus and so on around Seto inland sea in Japan. It is attributed to the increase of primary production due to eutrophication. and the rising and settling from the sediment containing nutrient salt. Furthermore, the recent research shows that nutrient salt such as nitrogen and phosphorus, flows into Kii channel from land as well as the Pacific ocean. To investigate the distribution of water quality and flow and residual current in Kitan strait, the field observations were carried out. The field data were obtained a time each season from 1999 to 2002. The results of observations and data of other research institution are used to understand the mechanism of pollution in the strait.

• The Journal of the Korea Contents Association
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• v.17 no.6
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• pp.98-105
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• 2017

The medical institution considers liability management problems as a direct factor in managerial risks, such as bankruptcy. Cash Flow provides useful information to necessary funds and predicting bankruptcy. The study for 24 general hospitals and 23 hospitals, a regression analysis was performed to determine the impact of cash flows on the debt repayment capability, a multivariate discrimination analysis was conducted to find out how to manage cash flow for the risk posed by debt. The analysis results, For general hospitals, the level of debt repayment capability was done to net income, increase of payables from operating activities and decrease of patient receivables and inventories from operating activities. If there is no dept repayment capability, it is necessary to increase the net income, increase the expenses not involving cash outflows, decrease of patient receivables and increase of payables from operating activities. For hospitals, the level of debt repayment capability was done to net income, increase of expenses not involving cash outflows and payables from operating activities, decrease of income not involving cash inflows, decrease of patient receivables and inventories from operating activities. If there is no dept repayment capability, it is necessary to increase of payables from operating activities.

• Journal of Soil and Groundwater Environment
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• v.18 no.3
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• pp.52-57
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• 2013

Radon, which is one of the radioactive elements in the natural world, exists in the atmosphere and water. When this element inflows into the human body, it carries the risks of developing lung cancer and stomach cancer. Therefore, in this study, an effective 10 L scaled reactor was produced to mitigate radon in water and the radon mitigation efficiency in water following the changes in water temperature and amount of aeration were evaluated. Based on this, the radon mitigation efficiency (SRRR; Specific radon removal rate) was derived per unit air volume. According to the study result, when water temperature increased from $10^{\circ}C$ to $16^{\circ}C$, the SRRR value increased from 95 $nCi/m^3{\cdot}L$ to 134.4 $nCi/m^3{\cdot}L$, and when the amount of aeration increased from 0.2 L/min to 1 L/min, the SRRR value decreased from 198.1 $nCi/m^3{\cdot}L$ to 72.2 $nCi/m^3{\cdot}L$. Therefore, based on the experimental results, it is considered that it can be applied as a examination factor and objective indicator during the design of future radon-in-water mitigation systems.

• Journal of Korean Society on Water Environment
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• v.29 no.3
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• pp.354-364
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• 2013

The performance of the stormwater wetlands can be significantly influenced by antecedent stormwater in storage at the commencement of a stormevent. As inflows are intermittent and stochastic in nature, the evaluation of the treatment efficiency of a stormwater wetland should be considered by runoff capture and water treatment characteristics during interevent periods. In this study, analytical probabilistic model is applied to identity runoff capture rate and treatment efficiency of the stormwater wetland. To achieve this, continuous rainfall data recorded in Busan for 31 years has been analyzed to derive the runoff capture rate, and 1st order kinetic decay constants ($k_V$, 1/d) are calculated from regression analysis to identify pollutants removal during interevent periods. The results show that about 60.9% of annual average runoff is captured through the stormwater wetland. The annual average treatment efficiencies of SS, BOD, COD, TN and TP is about 11.4, 8.9, 9.8, 4.3 and 9.6%, respectively. The analytical model has been compared with the numerical model and it shows that analytical model is valid. Performance evaluation methods developed in this study has the advantages of considering characteristics of rainfall-runoff, facility type and pollutant removal.