• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.03a
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• pp.283-292
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• 2008

The foremost criterion in the design of a Satellite Launch Vehicle(SLV) is its performance capability to boost the designated payload to the desired mission orbit; it starts from focusing on the SLV configuration to achieve the velocity requirements($}\Delta}V$) for the mission. In this paper we review an analytical approach which is suitable enough for preliminary conceptual design and is used previously to optimize stage configurations for Two Stage to Orbit SLV for Low Earth Orbit(LEO) Missions; we have extended this approach to Three Stage to Orbit SLV and compared different propellant options for the mission. The objective is to minimize the Gross Lift off Weight(GLOW). The primary performance figures of merit were the total inert weight of the SLV and the payload weight that the SLV could lift into LEO, given candidate propulsion systems. The optimization is achieved by configuring the $}\Delta}V$ between stages. A comparison of configurations of single-stage and multi-stage SLVs is made for different propellants. Based upon the optimized stage configurations a comparative performance analysis is made between Liquid and Solid fueled SLV. A 3 degree of freedom trajectory-analysis program is modeled in SIMULINK and used to conduct the performance analysis. Furthermore, a cost analysis is performed on our stage optimized SLVs. The cost estimation relationships(CER) used give us a comparison of development and fabrication costs for the Liquid vs. Solid fueled SLV in man years. The pros and cons of the production, operation ability, performance, responsiveness, logistics, price, shelf life, storage etc of both Solid and Liquid fueled SLVs are discussed. The statistics and data are used from existing or historical(real) SLV stages.

• International Journal of Computer Science & Network Security
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• v.23 no.10
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• pp.97-106
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• 2023

Sentiment analysis using social network platforms such as Twitter has achieved tremendous results. Twitter is an online social networking site that contains a rich amount of data. The platform is known as an information channel corresponding to different sites and categories. Tweets are most often publicly accessible with very few limitations and security options available. Twitter also has powerful tools to enhance the utility of Twitter and a powerful search system to make publicly accessible the recently posted tweets by keyword. As popular social media, Twitter has the potential for interconnectivity of information, reviews, updates, and all of which is important to engage the targeted population. In this work, numerous methods that perform a classification of tweet sentiment in Twitter is discussed. There has been a lot of work in the field of sentiment analysis of Twitter data. This study provides a comprehensive analysis of the most standard and widely applicable techniques for opinion mining that are based on machine learning and lexicon-based along with their metrics. The proposed work is helpful to analyze the information in the tweets where opinions are highly unstructured, heterogeneous, and polarized positive, negative or neutral. In order to validate the performance of the proposed framework, an extensive series of experiments has been performed on the real world twitter dataset that alter to show the effectiveness of the proposed framework. This research effort also highlighted the recent challenges in the field of sentiment analysis along with the future scope of the proposed work.

• Korean Journal of Construction Engineering and Management
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• v.15 no.1
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• pp.111-121
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• 2014

The Clean Development Mechanism (CDM) allows New & Renewable Energy projects to make additional income by selling CER's, which represent the amount of Green House Gases(GHG) that is reduced in the project. However, forward contracts used to hedge fluctuating market prices does not allow projects to sell CER's at a premium. As an alternate approach to maximize CER revenue, CER's are modeled as a 'real option', in which CER's are sold only above the desired sales price. Using the Binomial Option Pricing model, the resultant lattices are used to determine whether to sell, defer or abandon the option at individual nodes. Overlaying Pascal's Triangle on the lattices also enabled the calculation of the annual probabilities for deferring CER sales without incurring downside losses. Application to an actual Landfill Gas project showed increased overall NPV, and that CER sales could be deferred at a maximum of 2 years. The proposed framework allows transparency in the analysis and provides valuable and strategical information when making investment decisions related to CER sales of CDM projects.

• Journal of the Korean association of regional geographers
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• v.4 no.2
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• pp.79-94
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• 1998

This study begins with emphasis on the approach to public policy development and the extent to which a GIS framework can be used to evaluate projects objectively. This paper relates to public policy making and the use of GIS as a strategic management tool rather than the development of GIS technologies which has been the focus of attention since the advent of the first generation GIS systems in the 1960s. In order to consolidate a view towards public policy, the aim of this study is to show the advantages of using GIS to generate results which could be evaluated by cost and benefit analysis giving options of the alternative methods to estimate the feasibility of projects (both tangible and intangible) in a real public policy scenario. This study also reports that the tangible benefits associated with the GIS projects are better information processing, the easy analysis of data and the cost savings of map updates and printing, whilst the intangible benefits include quality decision making, and precise management of data through computing networks. In GIS context, the task of analysing and evaluating GIS projects is assumed in order to facilitate scientific and quantitative cost-benefit analysis. Previous methods of the cost-benefit analysis has not fully supported the evaluation of the intangible benefits and it has not been possible to make public policy realistic or scientifically understandable limiting decision makers in public domain. With the GIS decision makers are able to explore the potential of projects with this powerful decision supporting tool in practical application. On the basis of its potentials and limitations to cost-benefit analysis, therefore, it can be concluded that more flexible analysis and evaluation methodologies are needed to extend into the intangible benefits. In order to balance the evaluation of both quantitative and qualitative approaches on the cost-benefit analysis new or additional utilities will be required for the next GIS generation appraisal tool.

• Land and Housing Review
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• v.5 no.3
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• pp.137-149
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• 2014

The authors derived rental housing policy measures that are appropriate for the current conditions of Korean housing supply and demand based on the confirmation of the issues of Korean rental housing system and reviewing implications from review of cases of foreign countries and these measures can be categorized into linkage with the urban regeneration and multi-functional development, acquisition of financial resources, operational management, policy and institutional aspects. For the expansion of supply of rental housing, it is essential to link the rental housing policy with urban regeneration. To pursue regeneration of underdeveloped areas and expansion of supply of rental housing in line with urban regeneration, more development sites should be added. Further, the rental home policy must be integrated into a new paradigm that includes securing commercial viability and providing various residential conveniences through multi-functional development. In addition, diversification of developers of real estates turning away from the existing framework of policy that has been focused only on the state-led housing supply so that local governments and private sector players can take part in. Next, new options for funding the supply of rental housing must be sought. First, raising financial resources sequentially through cyclical development approach could be considered. Or, various funding schemes including utilizing Tax-increment financing (TIF) based on the local tax revenues that will be accrued after the development projects and supply of rental housing. Or there should be various schemes to raise funds including utilization of TIFs that are based on the revenues that will be realized after the development projects and supply of rental housing, or utilizing REITs where funds can be provided through private sector investments. Also, getting out from the planning practice that focused only on physical expansion of supply of rental housing, continual operational management must be performed even after the development. These activities must be supported through establishment of control tower at the national level and continuous attention must be paid even after the development by developing specialized operational management companies that are led by private sector players. Finally, in addition to the hardware support that is focused on the public rental housing only, software support such as conditional provision of housing voucher or tax exemption for low-income classes should be provided, too. In other words, a shift from policies that are supplier-centric to ones that are customer-centric must take place.