• International Journal of Highway Engineering
• /
• v.16 no.5
• /
• pp.39-47
• /
• 2014

PURPOSES : This study aimed to analyze economic effect of recycled aggregate production on job-site airport pavement. METHODS : The validation of site recycling for waste concrete as economic efficiency is analyzed through the case study of site recycling at an O airport pavement construction. The break-even point for the cost of site recycling was estimated according to two different waste concrete processing methods such as job-site recycling and processing on commission (or plant). RESULTS : Job-site recycling cost decreases as the use rate of job-site recycled concrete aggregate increases, or the amount of concrete waste increases, but transporting distance decreases. It was shown in an O airport case that as the use rate of job-site recycled concrete aggregate exceeds 61.4 %, the job-site recycling cost is cheaper than the processing cost on commission. CONCLUSIONS : The results of this study can utilize basic data of feasibility for site recycling of waste concrete on airport pavement construction.

• International Journal of Aeronautical and Space Sciences
• /
• v.12 no.3
• /
• pp.288-295
• /
• 2011

This paper addresses minimum-fuel, two-dimensional trajectory optimization for a soft lunar landing from a parking orbit to a desired landing site. The landing site is usually not considered when performing trajectory optimization so that the landing problem can be handled. However, for precise trajectories for landing at a desired site to be designed, the landing site has to be considered as the terminal constraint. To convert the trajectory optimization problem into a parameter optimization problem, a pseudospectral method was used, and C code for feasible sequential quadratic programming was used as a numerical solver. To check the reliability of the results obtained, a feasibility check was performed.

• Journal of Aerospace System Engineering
• /
• v.18 no.3
• /
• pp.27-33
• /
• 2024

According to the success of the Nuri Space Launch Vehicle (KSLV-II) and the development goal of the next generation space launch vehicle (KSLV-III), it is expected that the domestic geostationary satellite capability will be increased from (1 to 3.7) ton. Also, it is predicted that substantial ability of about 1 ton can be provided for the space exploration of the Moon, Mars, asteroids, etc. The Goheung space launch site is optimized for sun-synchronous small satellites, and due to the essential precondition that the launch trajectory does not impinge another country's sovereign airspace, it is not satisfactory as a geostationary satellite launching site. Its latitude also requires more energy to shape the rotating orbital plane from the initial injection status. This results in a decreasing factor of economic feasibility, including the operating complexity. Therefore, in parallel with the development of a next generation space launch vehicle, the practical process for acquisition of oversea land or sea space launch site near the Earth's equator and research for the optimization of orbiting methods of geostationary satellite injection must be continued.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.35 no.2
• /
• pp.447-453
• /
• 2015

This study proposed evaluation indices and weights for objectively evaluating the validity of rail station area development site. In this study, evaluation indices were selected by quantification, application of a new rail station, sustainability of data collection, correlation of indices and expert decision-making. As a result, 8 indices such as railway and subway demand, the ratio of land price etc. were selected and these indices could be classified into demand, feasibility and regionality. AHP (Analytic Hierarchy Process) result showed that the weights of demand (0.486) and feasibility (0.369) were more important than that of regionality (0.145). The application result on 75 existing railway stations showed that an important consideration of railway station area development site was a rail and subway demand on Seoul metropolitan area and was a feasibility on local area. Therefore, the selection of a rail station area development site may be determined based on demand and feasibility. In addition, these results are expected to be utilized as basic data for making decisions on the rail station area development at an initial stage.

• Korean Journal of Soil Science and Fertilizer
• /
• v.34 no.1
• /
• pp.42-54
• /
• 2001

The use of nitrogen fertilizer in intensive agricultural production is of major concern due to its role on agricultural productivity and water quality. Crop production inputs on farm are usually applied at a uniform rate across an entire field. However, actual input requirements often vary within fields. The field variations in yield potential, soil moisture, soil N status, and the efficiency of fertilizer use, uniform application of crop production inputs does not allow optimum efficiency or profitability. This occurs because uniform application often results in areas of over- and under-application which may affect water quality and crop yield. This study used biophysical and economic models to assess the economic feasibility and water quality benefits of site specific nitrogen management for 10 soil types and 35 sample fields in Goodwater Creek watershed located near Centralia, Missouri. Results showed that the economic feasibility and water quality benefits of variable rate application were sensitive to the distribution of soil types within a field. Variable rate(VR) application was not uniformly more profitable than uniform rate(UR) application for the four agricultural systems evaluated and the water quality benefits were insubstantial relative to uniform application of N.

• Journal of the Korea Institute of Building Construction
• /
• v.9 no.3
• /
• pp.117-125
• /
• 2009

With construction industry recession, many construction companies are increasingly conducting the development projects by themselves. However, housing projects requested by developers still stand large portion. Although many studies on feasibility analysis were released, they mainly focused on economic feasibility and lacked research on factors and criterions of overall project. Also, because previous studies overly break downed factors related to project, they rarely used in practice. Therefore, this study developed the feasibility analysis model of housing development projects to help main contractors to easily and effectively decide if it is feasible enough to promote the projects requested by developers, and verified the reliability of the model. In this study, thirty one driving factors were identified under seven different categories and the criterion of each factor was also developed. The survey on important index of each factor found 'salability', 'economic feasibility', 'site location' and 'method of raising fund' significant. 12 projects were tested by the model and its results showed resonable reliability.

• Journal of Environmental Science International
• /
• v.3 no.4
• /
• pp.417-425
• /
• 1994

Leachate from municipal landfill site is known to be hard to treat because it commonly contains various toxic material and heavy metals. In addition, portions of biodegradable organic substances in leachate are decreasing in the course of wastes stabilization, which is one of the critical reason for inefficient biological treatment at the end stage of landfill site operation. So this study was conducted to examine the feasibility of municipal lanuill leachate pretreatment using electrolysis. The optimum electrode combination was made. The optimum electrode combination was found to be lead and graphite.

• Journal of Astronomy and Space Sciences
• /
• v.15 no.1
• /
• pp.261-267
• /
• 1998

We present a feasibility study of a data receiving station in Korea to be used for a 50cm UV space telescope proposed by CSA. The feasibility was investigated by examining the spacecraft visibiligy from four different cities in Korea, based on the orbital characteristics of the proposed spacecraft, i.e. inclination of $28.5^{\circ}$and circular orbit altitude of 690km. The satellite can be accessed from Korea about 4 times a day, each pass having the duration of to 9 minutes depending on the elevation mask and the latitude of each site. Provided that the X-Band signal can be retrieved from $10^{\circ}$ elevation. this study demonstrates that a ground station placed in any of the four cities can be used for a reasonable backup downlink of the science data gathered by the proposed UV space telescope.

• Journal of The Korean Society of Agricultural Engineers
• /
• v.46 no.5
• /
• pp.131-139
• /
• 2004

In this study, on-site sewage treatment tests were conducted using the Absorbent Biofilter System (ABS) under different hydraulic loading rates to examine its treatment characteristics and efficiencies and to determine its feasibility as a small on-site sewage treatment system in a rural area. Results showed that the removal rates of BOD and SS were satisfactory at hydraulic loading rates of 100~150 cm/day, meeting the Korean effluent water quality standards for the riparian zone (10 mg/L). In the case of nutrients (N, P), however, the system did not perform well, necessitating further improvement for nutrient removal. A comparative analysis indicated that as a small on-site sewage treatment system, the ABS would be more suitable than other treatment systems in terms of performance stability, maintenance requirement, and cost-effectiveness and could be applied as an alternative treatment system in Korean rural areas.

• Journal of the Korean Institute of Rural Architecture
• /
• v.7 no.1
• /
• pp.11-18
• /
• 2005

This study analyzes the feasibility of constructing Geochang high technology industrial complex and present s the site, plan and development strategies. As a result, first, the Wallpyung area, superior form others in site characteristics, accessibility, surrounding facilities, was decided to the plan site. Second, the plan tries to adapt in the environment and maximizes the spatial link and user conveniences. Third, a transportation plan includes a circulation street network that adapt in topography, and considered future traffic situation and accessibility, hierarchy of road etc. Fourth, it also plans to locate a environment-friendly central park in the middle of site and buffer areas along at the outer sites and both sides of the roads. Fifth, for the development, it is advised to construct a public institution which manages the whole project and it is necessary to build a cooperate system.