• Journal of Korean Tunnelling and Underground Space Association
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• v.22 no.3
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• pp.219-237
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• 2020

Rapid economic development and urban population growth have been increasing the necessity for underground space exploration and utilization due to the need of upgrading and expanding the existing infrastructures. TBM has been widely used to construct underground structures with high advance rate and minimal ground disturbance. Two important design parameters, which are available thrust capacity and cutterhead torque, should be estimated for any project in addition to proper selection of TBM type. However, the conventional thrust force and torque estimation model only depends on the empirical equation, which hinders the design process of the optimal thrust hydraulic system and the appropriate hydraulic components. In this study, four thrust and torque calculation models are derived and explained. For TBM design practice, the four estimation models are compared and discussed.

• Journal of Korea Trade
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• v.25 no.1
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• pp.89-111
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• 2021

Purpose - The U.S. Trade Preference Expansion Act (TPEA) of 2015 enables the US Department of Commerce (DOC) to inflate dumping margin when the particular market situation (PMS) exists in the exporter's home market. DOC applied PMS provisions to the steel products from Korea. This paper analyzes whether DOC's calculation by using the regression analysis is consistent with WTO rules. Design/methodology - This paper analyzes the PMS application in law and regression analysis that extends the data period from 10 years to 18 years using the same economic model with DOC, and changes the country group according to the quantities of steelmaking capacity. Findings - Results show that DOC's argument conflating the sales-based with cost-based PMS designed to inflate dumping margins might not be consistent with WTO Antidumping Agreement Article 2.2 and 2.2.1.1 in which costs shall normally be calculated on the basis of records kept by the exporter, providing generally accepted accounting principles and reasonably reflection of the costs and PMS that exists in the Korean steel product markets. Even if it will be consistent, DOC's calculated margin by the regression analysis using a 10-year data is a big gap (5 times) compared with an 18-year data projection and different countries' data through the same methodology, which is a huge gap of regression coefficient. It means that dumping margin would be very wide range from 7.8% to 38.54% and unstable to calculate. Inflating dumping margin by DOC using regression analysis would not only be inconsistent with WTO rules, but also projection result is unreliable. Originality/value - Literature papers have mainly analyzed WTO law itself. This paper however, would be the first attempt to analyze the DOC's new way of dumping margin calculation in both manners of law and an empirical methodology perspective at the same time.

• Journal of People, Plants, and Environment
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• v.23 no.3
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• pp.321-332
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• 2020

Background and objective: The concept of 'money' in the numbers and operations domain is a fundamentally necessary domain of economic life. This study was conducted to examine the effects of a horticulture-mathematics integration program on mathematical attitude and money calculating ability of high school students with intellectual disabilities. Methods: We analyzed the changes in the mathematical attitude and money calculating ability of students with mild intellectual disabilities in S special school in the city of D, Republic of Korea, with 12 students in the control group and 12 students in the experimental group, from August 27 to October 29, 2019. Results: The results of the comparison showed no statistically significant changes in the three items of mathematical attitude for the control group, while the experimental group, which took part in the horticulture-mathematics integration program, showed statistically significant differences across all three items, such as self-concept about the subject (p = .003), attitude toward the subject (p = .004), and study habit related to the subject (p = .012). The horticulture-mathematics integration program, which was developed by integrating horticultural activities and the mathematics curriculum, used plants and horticultural activities to provide students with positive experiences in mathematics. These included the sense of closeness, curiosity, interest, attention, and enjoyment, leading to positive changes in mathematical attitude. In terms of money calculating ability, both the control group and experimental group showed statistical differences across the three items, but the experimental group showed greater degrees of increase, 15.0 or more, in the scores compared to the control group. Conclusion: These results suggest that utilizing horticultural materials as a part of purchase learning programs with elements of money calculation chapters in the mathematics curriculum could lead to the improvement of students' ability in money calculation. These positive changes are thought to be related to the high degrees of interest in horticulture among students, which led to active participation in the program and enabled the simple and repeated purchase activities in the program to generate positive changes in the money calculation ability of the students.

• The Journal of the Convergence on Culture Technology
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• v.9 no.6
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• pp.1049-1055
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• 2023

The utilization of agricultural drones for pest control operations has been increasing due to its economic efficiency. However, variations in the effectiveness of these operations occur depending on the operator's proficiency. In this study, we applied a smart operating mode to overcome the limitations of manual flight mode and proposed a numerical model. Through comparative validation with prior research, we conducted experimental verification. As a result, we determined the spray time and calculation of spray area for each drone model. We selected a drone for pest control with a high similarity to the numerical model and verified it experimentally. Through this, we confirmed that the application of the smart operating mode is more effective in terms of calculation of spray area and operational efficiency compared to manual flight mode.

• The Mathematical Education
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• v.24 no.2
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• pp.74-104
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• 1986

This study aims at investigating the correlation between such variables as a child's family circumstance and personality and that of the child's mathematical ability. For the objects of the study five hundreds and sixteen students (male 273, female 243) were andomly selected from the fifth grade primary school students in the city of Seoul. For the tool of measure the investigation of Korean family circumstances with particular characteristics, the personality test by Chong Pom Mo and Kim Ho Kwon, and the intelligence test by Lee Sang Ro, Chin Whal Kyo and Pyon Chang Jin were employed. For the statistical analysis S. A. S. C., the statistical analysis package of KAIST was employed. The resutis of the test can be summarized as follows. The correlation between the variable of family Circumstance and that of mathematical alility 1) In case of the significance level 0.05 the education of the childs mother and the order of the child's birth have much to do with the perception speed. In case of the significance level 0.1 it makes some difference in the child's perception spead whether the clild's mother has a job or not. 2) In case of the significance level 0.05 the education of the child's father and mother, the father's job and the type of habitation have influence on the child's perception of space. 3) In case of the significance level 0.05 the education of the child's father and mother, the father's job, the order of the child's birth, the type of habitation, their religion, and their cultural, and economic standard have influence on the child's ability of inference. 4) In case of the significance level 0.05 the education of the child's father and mother, the father's job, the type of habitation, their religion and their cultural and economic standard have influence on the child's ability of calculation. 5) In case of the significance level 0.05 any variable of the child's family circumstance has nothing to do with the child's memory. In case of the significance level 0, 1 the type of family and the type of habitation have effect on the child's memory. 6) In case of the significance level 0.05 the education of the child's parents, the jobs of the parents, the type of habtation, their religion, and their cultural and economic standard have influence on the child's linguistic notion. The correlation between the variable of the child's personality and that of the child's mathematical ability 1) In regard to the priority of the variables influencing the child's perception speed, the child's discretion comes first in order, and then sociability and impulsiveness of the child. 2) The child's discretion has effect on the child's space perception. 3) The child's discretion has effect on the child's ability of inference. 4) In regard to the child's ability of calculation the child's discretion comes first in order, and then impulsiveness and sociability of the child. 5) The child's discretion has effect on memory. 6) The child's discretion has effect on the child's linguistic notion.

• Economic and Environmental Geology
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• v.54 no.6
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• pp.733-741
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• 2021

Globally, in accordance with the goals set forth in the 2015 Paris Climate Agreement, each country has established and declared a reduction target for carbon neutrality by 2050. The roadmaps for establishing long-term greenhouse gas emissions development strategies and setting reduction targets have been announced. As the international community accelerates the transition to the net-zero society, 128 countries have declared net-zero by the end of 2020, and the net-zero declaration continues to expand around G20 member states. In December 2020, Korea announced the "2050 Net-zero Strategy" to establish a foundation for simultaneously achieving carbon reduction, economic growth, and improved quality of life for the people through active response to the net-zero, and pursuing policy tasks in stages to do this. Comprehensive carbon management is insufficient due to the lack of comprehensive carbon management due to the departure from the areas of mandatory reduction, such as the GHG energy target management system and the GHG emissions trading offset system implemented to reduce greenhouse gases in Korea. Currently, there is no cases for estimation or calculation of carbon dioxide emissions for the Mine Reclamation projects. It is reviewed the standard methods proposed by domestic and foreign carbon emission calculation methods and proposed appropriate carbon emission estimation methods for the Mine Reclamation projects in this study.

• Economic and Environmental Geology
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• v.31 no.6
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• pp.499-508
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• 1998

The Imgok Creek is located in the Gangreung coal field, which has been known that sulfides are more abundant than other coal fields in Korea, and it has been severly contaminated by acid mine drainage (AMD) discharging from the abandoned coal mines, such as the Youngdong, the Dongduk and the Waryong coal mines. The purposes of this study are to synthetically assess the contamination of natural water, stream sediment and cultivated soils, and to provide the basic data for AMD treatment. Geochemical samples were collected in December, 1996 (dry season) and April, 1997 (after three day's rainfall). TDS of the Youngdong mine water was remarkably higher than those of other mine waters. In the Imgok Creek, concentrations of most elements, except Fe decreased with distance by dilution caused by the inflow of uncontaminated tributaries. From the results of NAMDI and $I_{geo}$ calculation, the Youngdong coal mine was the main contamination source of the study area. Groundwater pollution was not yet confirmed in this study and the paddy and farm land soils were also not yet contaminated by mining activity based on the pollution index ranging from 0.27 to 0.47.

• New & Renewable Energy
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• v.3 no.4
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• pp.31-37
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• 2007

Because of their low operating and maintaining costs, ground-source heat pump(GSHP) systems are an increasingly popular choice for providing heating, cooling and water heating to public and commercial buildings. Despite these advantages and the growing awareness, GSHP systems to residential sectors have not been adopted in Korea until recently. A feasibility study of a residential GSHP system was therefore conducted using the traditional life cycle cost(LCC) analysis within the current electricity price framework and potential scenarios of that framework. As a result, when the current residential electricity costs for running the GSHP system are applied, the GSHP system has weak competitiveness to conventional HV AC systems considered. However, when the operating costs are calculated in the modified price frameworks of electricity, the residential GSHP system has the lower LCC than the existing cooling and heating equipments. The calculation results also show that the residential GSHP system has lower annual prime energy consumption and total pollutant emissions than the alternative HVAC systems considered in this work.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.18 no.4
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• pp.165-170
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• 2004

This paper presents summary results of direct interview survey of Korean industrial customers conducted to evaluate the direct and short duration interruption costs resulting from local random electrical supply interruptions. The cost is evaluated using the questionnaires authors designed, which are mainly on the experience or preparatory actions consumers predicted they would take. Economic evaluation of reliability that traditionally takes into account duration and frequency of interruption does not accurately reflect the lost value or economic impacts of industrial customer, especially large size, caused by any kind of interruption. So, to imply the substantial difference in costs incurred by different customer group, the authors apply the international standards, i.e. IEC, IEEE, to the analysis on the interruption costs.

• Economic and Environmental Geology
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• v.28 no.3
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• pp.213-220
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• 1995

Geochemistry of stream water and sediment collected in the vicinity of the Donghae coal mine in the Samchuk coalfied were investigated in order to evaluate the environmental impacts of acid mine drainage. The pH of stream water ranges from 2.85(at 2 km away from the mine) to 7.92(at uncontaminated tributary). The main cation and anion species in the upper stream are $Ca^{2+}$ and $SO_{4}{^2-}$, respectively. The level of pH and the amount of $HCO^{3-}$ in stream water increase to the downstream and where uncontaminated small tributaries are joining, and in the area covered with limestone. From the results of thermodynamic calculation, the main forms of iron in stream water are estimated as $Fe^{2+}$ and $FeSO_{4}{^0}$, and most of them could be precipitated as FeO(OH) with increase of pH. The white precipitates in stream sediments particularly found around the coal mine are proved to be $Al(OH)_3$ by XRD and XRF analysis. As a result of investigation for seasonal variation of AMD, the level of pH decreased and conductivity increased in dry season.