• Journal of Environmental Impact Assessment
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• v.21 no.1
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• pp.25-39
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• 2012

This study was aimed to assess the effects of additional installation of two different types of weirs, one is a curtain-type weir and another is a submerged-type weir, on the control of algal growth in Daechung Reservoir. A two-dimensional(2D) coupled hydrodynamic and eutrophication model that can accommodate vertical movement of the curtain weir following the water surface variations was verified using field data obtained in two distinctive hydrological years; dry(2008) and wet(2010). The model adequately simulated the temporal and spatial variations of water temperature, nutrients and algal(Chl-a) concentrations during the periods. The effectiveness of curtain weir on the control of algal bloom was evaluated by applying the model to 2001(dry year) and 2010 assuming 6 different scenarios according to installation locations. The curtain weirs that already installed at 3, 5, 7 sites(scenario C-2) showed significant effect on the control of algal growth in the reservoir; the reduction rates of algal concentration were placed in the range of 7.5~31.5% and 9.1~44.9% for 2001 and 2010, respectively. However the simulation results revealed that additional installation of curtain weirs(scenario C-3~C-6) in the bay area (choosori) have marginal effect. The effectiveness of submerged weir was evaluated against 2010 assuming 7 different scenarios according to installation locations, but all scenarios(S-1~S-7) showed neglectable or negative effect on the control of algal growth.

• Journal of the Korean Society of Marine Environment & Safety
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• v.25 no.4
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• pp.441-447
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• 2019

Since emergency response training for maritime safety and safety education of maritime education institutions are conducted based on the set scenarios and education contents, there are limitations in the reduction of human error and response to various situations. Although there is a need for improvement, there is no way to improve response capabilities by assessing existing education training and securing diversity in situations. This study proposes a theoretical procedure analyzer method to model the diversity of situations for the improvement of emergency response training. This paper defines the human and system theoretical procedure analysis model (HSTPA) based on the organic relationship of the source and system. The limitations of the existing training were derived by analyzing the errors that each component could produce and applying them to the fire response training scenarios requiring vertical reporting systems and responses. The segmentation and inspection of training scenario considerations applying the proposed HSTPA model is believed to help create diverse and realistic scenarios in emergency response training and education, and improve the situation judgment understanding and response capabilities of the subjects.

• Journal of Korea Water Resources Association
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• v.56 no.4
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• pp.273-284
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• 2023

Water supply is continuously suffering from frequent droughts under climate change, and such extreme events are expected to become more frequent due to climate change. In this study, the decision scaling method was introduced to evaluate the drought vulnerability under future climate change in a wider range. As a result, the water supply reliability of the Boryeong Dam ranged from 95.80% to 98.13% to the condition of the aqueduct which was constructed at the Boryeong Dam. Furthermore, the Boryeong Dam was discovered to be vulnerable under climate change scenarios. Hence, genetic algorithm-based hedging rules were developed to evaluate the reduction effect of drought vulnerability. Moreover, three demand scenarios (high, standard, and low demand) were also considered to reflect the future socio-economic change in the Boryeong Dam. By analyzing quantitative reliability and the probability of extreme drought occurrence under 5% of the water storage rate, all hedging rules demonstrated that they were superior in preparing for extreme drought under low-demand scenarios.

• Journal of the Korean Institute of Gas
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• v.5 no.2 s.14
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• pp.9-13
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• 2001

A complete spectrum of risk assessment including qualitative and quantitative approaches were performed for the POSCO's Batch Annealing Furnace (BAF) gas systems. The purpose of BAF is to enhance the quality of steel by annealing it with either hydrogen/nitrogen mixture gas or pure hydrogen gas. Number of gas leak scenarios were identified to generate frequency of their occurrences. With the hypothetical accident scenarios given, fire/explosion impact studies were performed to estimate magnitude of significant consequences. Several different indices were also presented from which practical safety improvement action items could be established.

• Transactions of the Korean hydrogen and new energy society
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• v.28 no.6
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• pp.635-641
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• 2017

In this study, the components of packaged hydrogen filling station were analyzed and risk factors were examined. Risk scenarios were constructed and quantitative risk assessments were conducted through a general risk assessment program (phast/safeti 7.2). Through the risk assessment, the range of damage according to accident scenarios and the ranking that affects the damage according to the risk factors are listed, and scope of damage and countermeasures for risk reduction are provided. The quantitative risk assessment result of the packaged hydrogen filling station through this task will be used as the basic data for improving the safety of the packaged filling system and preparing safety standards.

• Geomechanics and Engineering
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• v.20 no.2
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• pp.165-174
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• 2020

The enzyme-induced carbonate precipitation (EICP) method has been investigated to improve the hydro-mechanical properties of natural soil deposits. This study was conducted to explore the stiffness evolution during various stress scenarios. First, the optimal concentration of urea, CaCl₂, and urease for the maximum efficiency of calcite precipitation was identified. The results show that the optimal recipe is 0.5 g/L and 0.9 g/L of urease for 0.5 M CaCl₂ and 1 M CaCl₂ solutions with a urea-CaCl₂ molar ratio of 1.5. The shear stiffness of EICP-treated sands remains constant up to debonding stresses, and further loading induces the reduction of S-wave velocity. It was also found that the debonding stress at which stiffness loss occurs depends on the void ratio, not on cementation solution. Repeated loading-unloading deteriorates the bonding quality, thereby reducing the debonding stress. Scanning electron microscopy and X-ray images reveal that higher concentrations of CaCl₂ solution facilitate heterogeneous nucleation to form larger CaCO₃ nodules and 11-12 % of CaCO₃ forms at the interparticle contact as the main contributor to the evolution of shear stiffness.

• Journal of Navigation and Port Research
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• v.29 no.4
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• pp.319-325
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• 2005

Planning for the construction of ports and harbors usually takes place without the consideration of tsunamis because of their rare occurrence, approximately once every 100 years. However, recent warnings indicate that massive earthquakes could occur in Japan within the next 30 years. Earthquakes may generate large-scale tsunamis. Therefore, any tsunamis in the vicinity of Japan would also be expected to affect eastern Korea. Therefore, with the looming concerns of tsunamis and earthquakes, immediate attention must be given to the planning of ports and harbors. The warnings deserve an immediate response. The threatened regions cover a very large territory, and the degree of severity of the tsunamis is forecasted to be varied. Therefore, any modeling of the potential scenarios will require a broad array of possibilities. The objective of this paper is to consider the potential damage from tsunamis to ports and moored ships in Japan and Korea. In addition, consideration will be given to how the construction plans of ports and harbors should be changed to cope with the threats from earthquakes and tsunamis.

• Journal of Wellbeing Management and Applied Psychology
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• v.3 no.4
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• pp.1-4
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• 2020

Purpose: This research, based on the tariff reduction table negotiated by South Korea and China free trade area, the specific tariffs of the two countries in the implementation of the Korea-China Free Trade Agreement are calculated, and the global equilibrium model, the global trade analysis project (GTAP) model, is used to simulate and analyze the impact of the Korea-China free trade area on the output and trade of the two countries. Research design, data and methodology: The study conducted a survey on 2018 year GTAP 9.0data. After empirically analyzing the data, we believe that the Major industry in Korea and China will maintain its growth momentum. Results: This study shows that under the assumption that the average tariff of China and South Korea at the beginning of FTA was reduced to 20%, two scenarios were simulated. Two scenarios are simulated under the assumption that the average tariff of China and South Korea FTA will be reduced to 10%. Conclusions: This paper assumes that the average tariff of China-Korea FTA is set at 20%, 10% and zero tariff respectively in the early, middle and long term of the FTA construction. It considers the impact of China-Japan-Korea FTA on China- Korea FTA.

• Structural Engineering and Mechanics
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• v.84 no.4
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• pp.517-530
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• 2022

In re-assessing the Jacket-type fixed steel structures, the current standards often allow the simplicity of corrosion sections using local buckling or equivalent section approach to applying empirical formulae of frame stress and resistance analyses. However, those approaches can lead to significant errors for non-uniform corroded frames in a specific area, including force distribution, stress, and allowable strength of the tubular section, compared to the actual cases. This paper investigates a suitable approach to determine the actual stress on non-uniform corroded tubular frames under compression through the non-linear ABAQUS model by considering the effect of large deformation on the frame axis and the frame section. There are 3 scenarios of interest. In the 1st and 2nd scenarios with simple corrosion cases, the stress ratios using the numerical model and theoretical formulae correspond to the calculation of allowable strength reduction ratios in standards. However, scenario 3, which describes non-uniform corroded sections based on survey data, provides considerable differences in results. Therefore, it proves the reliable and effective results when using this method to analyze the resistance of the actual corroded section in the Jacket platforms.

• Wind and Structures
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• v.30 no.3
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• pp.219-229
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• 2020

Net pressures on roofs and walls of buildings are dependent on the internal and external pressure fluctuations. The variation of internal and external pressures are influenced by the size and location of the openings. The correlation of external and internal pressure influences the net pressures acting on cladding on different parts of the roof and walls. The peak internal and peak external pressures do not occur simultaneously, therefore, a reduction can be applied to the peak internal and external pressures to obtain a peak net pressure for cladding design. A 1:200 scale wind tunnel model study was conducted to determine the correlations of external and internal pressures and effective reduction to net pressures (i.e., net pressure factors, F_C) for roof and wall cladding. The results show that external and internal pressures on the windward roof and wall edges are well correlated. The largest ${\mathcal{C}}_{{\check{p},net}$, highest correlation coefficient and the highest F_C are obtained for different wind directions within 90° ≤ θ ≤ 135°, where the large openings are on the windward wall. The study also gives net pressure factors F_C for areas on the roof and wall cladding for nominally sealed buildings and the buildings with a large windward wall opening. These factors indicate that a 5% to 10% reduction to the action combination factor, K_C specified in AS/NZS 1170.2(2011) is possible for some critical design scenarios.