• Journal of the Korean Society of Mineral and Energy Resources Engineers
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• v.55 no.6
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• pp.553-563
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• 2018

In this study, the location conditions and optimal technologies required for creating urban municipalities that can utilize the space in an abandoned mine area, where there is no infrastructure related to recycling wastes and valuable metals, are investigated. The urban mining industry deals with mineral resources through the processing of high value-added industrial by-products and wastes, and it is a useful linkage industry for the development of mineral resources and prevention of mining hazards. Urban mining technologies targeted at the abandoned mine area constitute screening, extraction, and smelting for recycling waste products. By analyzing the technologies available, an industrial network can be developed for recycling waste batteries and catalysts, which are promising raw materials. It is also important to establish an appropriate location for related industries that can generate value-added resources, rather than the resource supply and demand conditions seen in general urban mines. In order to overcome the accessibility and infrastructure limitations, the economic foundation of the abandoned mine area should consider the linkage of raw material supply, key technologies for recycling useful mineral resources that are derived from urban mines, spatial and site conditions, and industrial characteristics.

• Journal of Korean Tunnelling and Underground Space Association
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• v.23 no.3
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• pp.167-181
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• 2021

New type of rock excavation method using a waterjet system is being developed to secure economic feasibility and to reduce vibrations during excavation. In waterjet rock excavation, overlapping of cutting width is essential for high efficiency. In this study, cutting experiments for granite specimens were performed using abrasive waterjet system according to the overlapping ratio and standoff distance. Based on the experimental results, the granite cutting performance was analyzed according to the overlapping ratio. In addition, removal shapes of the cross-section were analyzed in terms of the cutting depth, width, and volume after waterjet cutting. When the overlapping ratio is less than 58%, rock specimens are partially removed due to the insufficient overlapping ratio. However, when the overlapping ratio exceeds 67%, overcutting phenomenon is observed. For the partial overlapping ratio (i.e., 25~75%), cutting efficiency is increased in the removal volume. This study is expected to be used as the important basic data for determining the optimum overlapping ratio when the waterjet system is applied for rock excavation.

• Journal of the Korean Geosynthetics Society
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• v.21 no.1
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• pp.11-21
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• 2022

In this study, the individual vacuum seepage consolidation method, a new soft ground improvement method, was developed to supplement the conventional suction drain method (individual vacuum preloading method) and the geotechnical behavior was predicted through numerical analysis. If the individual vacuum seepage consolidation method applied, the effect of accelerating settlement and increasing the amount of settlement was high when the aquifer was located in the middle or at the bottom of the layer to the target improvement layer. It was found that the pumping amount in the aquifer does not affect the settlement behavior when it exceeds a certain level. Even vacuum pumping wells were installed in various locations, such as inside or outside of the embankment, the difference in settlement and horizontal displacement was insignificant. In addition, it was predicted that the settlement rate was the fastest and the horizontal displacement (inward) was large when both methods were carried out at the same time. Since this method can reach the target settlement amount very quickly, it was confirmed that it is possible to increase the spacing of vertical drain, thereby securing economic feasibility.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.15 no.2
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• pp.178-188
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• 2022

The introduction of virtual power plants is actively being discussed to solve the problem of grid acceptability caused by the spread of distributed renewable energy, which is the key to achieving carbon neutrality. However, a new business such as virtual power plants is difficult to secure economic feasibility at the initial stage of introduction because it is common that there is no compensation mechanism. Therefore, appropriate support including subsidy is required at the early stage. But, it is generally difficult to obtain the cost model to determine the subsidy level because of the lack of enough data for the new business model. In this study, a survey of domestic experts on the requirements, appropriate scale, and cost required for the introduction of virtual power plants is conducted. First, resource composition scenarios are designed from the survey results to consider the impact of the resource composition on the cost. Then, the cost estimation model is obtained using the individual cost estimation data for their resource compositions using logistic regression analysis. In the case study, appropriate initial subsidy levels are analyzed and compared for the virtual power plants on the scale of 20-500MW. The results show that mid-to-large resource composition cases show 29-51% lower cost than small-to-large resource composition cases.

• Environmental and Resource Economics Review
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• v.31 no.4
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• pp.645-668
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• 2022

Hydrogen energy is emerging as an important means of carbon neutrality in the various sectors including power, transportation, storage, and industrial processes. Fuel cell power plants are the fastest spreading in the hydrogen ecosystem and are one of the key power sources among means of implementing carbon neutrality in 2050. However, high volatility in system marginal price (SMP) and renewable energy certificate (REC) prices, which affect the profits of fuel cell power plants, delay the investment timing and deployment. This study applied the real option methodology to analyze how the dual uncertainties in both SMP and REC prices affect the investment trigger price level in the irreversible investment decision of fuel cell power plants. The analysis is summarized into the following three. First, under the current Renewable Portfolio Standard (RPS), dual price uncertainties passed on to plant owners has significantly increased the investment trigger price relative to one under the deterministic price case. Second, reducing the volatility of REC price by half of the current level caused a significant drop in investment trigger prices and its investment trigger price is similar to one caused by offering one additional REC multiplier. Third, investment trigger price based on gray hydrogen and green hydrogen were analyzed along with the existing byproduct hydrogen-based fuel cells, and in the case of gray hydrogen, economic feasibility were narrowed significantly with green hydrogen when carbon costs were applied. The results of this study suggest that the current RPS system works as an obstacle to the deployment of fuel cell power plants, and policy that provides more stable revenue to plants is needed to build a more cost-effective and stable hydrogen ecosystem.

• The Journal of the Korea institute of electronic communication sciences
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• v.17 no.2
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• pp.265-278
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• 2022

The global energy paradigm is rapidly changing by centering on carbon neutrality, and wind energy is positioning itself as a leader in renewable energy-based power sources. The success of onshore and offshore wind energy projects focuses on securing the economic feasibility of the project, which depends on securing high-quality wind resources and optimal arrangement of wind turbines. In the process of constructing the wind farm, the optimal arrangement method of wind turbines considering the main wind direction is important, and this is related to minimizing the wake effect caused by the fluid passing through the structure located on the windward side. The accuracy of the predictability of the wake effect is determined by the wake model and modeling technique that can properly simulate it. Therefore, in this paper, using WindSim, a commercial CFD model, the wake diffusion pattern is analyzed through the sensitivity study of each wake model of the proposed onshore wind farm located in the mountainous complex terrain in South Korea, and it is intended to be used as basic research data for wind energy projects in complex terrain in the future.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.3B
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• pp.271-281
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• 2008

To determine the flood protection elevation (FPE) in urban built-up areas, this study examines four possible methods: using the highest flood elevation in the past, extending base flood elevations of nearby watercourse to inland, and two simulation methods of inland flood under the same rainfall used in the watercourse planning nearby. According to the case study of the Jang-An Drainage Area, Seoul, the highest flood elevation in the past and simulation results of inland flood under the same rainfall in the watercourse planning nearby tend to get similar results, while extending base flood elevations of nearby watercourse to inland shows much higher elevations than other results. Meanwhile, cost-benefit analysis, when regulating residential/commercial uses below the FPE by each of four methods, suggest that planners need to consider carefully the economic feasibility of FPE used to choose appropriate methods.

• Journal of the Economic Geographical Society of Korea
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• v.21 no.2
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• pp.192-211
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• 2018

With significant influences of old industrial complex in September 2009, Ministry of Land, Infrastructure and Transport chose the 4 districts for the first pilot project. In December 2014, the second pilot project districts were established. In addition, there were 10 districts in April 2016 and 5 districts in April 2016 as the third pilot project and 5 districts in March 2017 as the fourth pilot project. In order to promote smooth business operation of the recycling business, we introduced the effective area designation and special system as stipulated in Article 39.12-13 of the Industrial Location and Development Act revised in May 2015. The effective area, It is a method that can promote propagation and diffusion of the rehabilitation business through visualization by making effective the promotion of the rehabilitation business and by promoting the business in consideration of the geographical feature of the region and industry group, The setting of the unreasonable effective area is based on the criteria and classification of the plan and the objective promotion method according to the individual characteristics of the aged industrial park because the delay of the rehabilitation business and the possibility of the increase of many problems are presented Be sure to Data Envelopment Analysis (DEA) and the old industrial complex database were constructed and utilized to classify the types of recycling projects. Therefore, in this study, it is necessary to strengthen the competitiveness of aged industrial complex by examining the correlation between the diagnosis of 83 aged industrial complex sites and the rehabilitation projects supported by the Ministry of Land, and the types of business promotion for aged industrial parks. It can be used as a guideline for the feasibility of the project.

• Journal of the Korean GEO-environmental Society
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• v.20 no.2
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• pp.41-48
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• 2019

Soil compaction is one of the most important activities in the area of civil works, including road construction, airport construction, port construction and backfilling construction of structures. Soil compaction, particularly in road construction, can be categorized into subgrade compaction and roadbed compaction, and is significant work that when done poorly can serve as a factor causing poor construction due to a lack of compaction. Currently, there are many different types of compaction tests, and the plate bearing test and the unit weight of soil test based on the sand cone method are commonly used to measure the degree of compaction, but many other methods are under development as it is difficult to secure economic efficiency. For the purpose of this research, a portable penetration meter called the Free-Fall Penetration Test (FFPT) was developed and manufactured. In this study, a homogeneous sample was obtained from the construction site and soil was classified through a sieve analysis test in order to perform grain size analysis and a specific gravity test for an indoor test. The principle of FFPT is that the penetration needle installed at the tip of an object put into free fall using gravity is used to measure the depth of penetration into the road surface after subgrade or roadbed compaction has been completed; the degree of compaction is obtained through the unit weight of soil test according to the sand cone method and the relationship between the degree of compaction and the depth of the penetration needle is verified. The maximum allowable grain size of soil is 2.36 mm. For $A_1$ compaction, a trend line was developed using the result of the test performed from a drop height of 10 cm, and coefficient of determination of the trend line was $R^2=0.8677$, while for $D_2$ compaction, coefficient of determination of the trend line was $R^2=0.9815$ when testing at a drop height of 20 cm. Free fall test was carried out with the drop height adjusted from 10 cm to 50 cm at increments of 10 cm. This study intends to compare and analyze the correlation between the degree of compaction obtained from the unit weight of soil test based on the sand cone method and the depth of penetration of the penetration needle obtained from the FFPT meter. As such, it is expected that a portable penetration tester will make it easy to test the degree of compaction at many construction sites, and will lead to a reduction in time, equipment, and manpower which are the disadvantages of the current degree of compaction test, ultimately contributing to accurate and simple measurements of the degree of compaction as well as greater economic feasibility.

• 한국사회정책
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• v.20 no.3
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• pp.77-115
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• 2013

The purpose of this study is to present empirical evidence for discussion of financing social welfare via estimating optimal tax burden in the main member countries of the OECD by using Hausman-Taylor method considering endogeneity of explanatory variables. Also, the author produced an international tax comparison index reflecting theoretical hypotheses on revenue-expenditure nexus within a model to compare real tax burden by countries and to examine feasibility of tax increase in Korea. As a result of the analysis, the higher the level of tax burden was, the higher the level of welfare expenditure was, indicating the connection between high burden and high welfare from the aspect of scale. The results also indicated that the subject countries recently entered into the state of low tax burden. Meanwhile, Korea had maintained low burden until the late 1990s but the tax burden soared up since the financial crisis related to the IMF. However, due to the impact of foreign economy and the tax reduction policy, it reentered into the low-burden state after 2009. On the other hand, the degree of social welfare expenditure's reducing tax burden has been gradually enhanced since the crisis. In this context, the current optimal tax burden ratio of Korea as of 2010 may be 25.8%~26.5% of GDP based on input of welfare expenditure variables, a percent that Korea was investigated to be a 'high tax burden-low ITC' country whose tax increase of 0.7~1.4%p may be feasible and that the success of tax system reform for tax increase might be higher probability when compare to others. However, measures of increasing social security contributions and consumption tax were analyzed to be improper from the aspect of managing finance when compared to increase in other tax items, considering the relatively higher ITC. Tax increase is not necessarily required though there may be room for tax increase; the optimal tax burden ratio can be understood as the level that may be achieved on average when compared to other nations, not as the "proper" level. Thus, discussion of tax increase should be accompanied with comprehensive understanding of models of economic developmental difference from nations and institutional & historical attributes included in specific tax mix.