• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.3
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• pp.523-531
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• 2007

In this paper, we are going to develop a newly designed indexing scheme which is compatible to manage the moving objects and propose a cost model of the scheme. We propose a dynamic hashing index that insertion/delete costs are low. The dynamic hashing structure is that apply dynamic hashing techniques to combine a hash and a tree to a spatial index. We analyzed the dynamic index structure and the cost model by the frequent position update of moving objects and verified through a performance assessment experiment. The results of our extensive experiments show that the newly proposed indexing schemes(Dynamic Hashing Index) are much more efficient than the traditional the fixed grid and R-tree.

• Journal of ILASS-Korea
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• v.24 no.2
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• pp.51-57
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• 2019

In this study, the spray atomization characteristics of urea injector used in SCR system for construction machinery was analyzed, and the uniformity index at the front of mixer and NOx conversion efficiency were evaluated through numerical analysis. Spray visualization and droplet size/velocity measurement were performed and the measured results were used to verify the spray analysis model to calculate the uniformity index in the exhaust gas after-treatment system. For the flow analysis, STAR-CCM, a three-dimensional CFD, was used and the uniformity index of the SCR system at the front of the mixer was calculated using the droplet dissociation model and the wall collision model. Finally, the DeNOx performance for the average condition of the NRTC driving mode was calculated to understand the NOx conversion efficiency reflecting the exhaust gas temperature. The simulation results show that the uniformity index at the front of mixer was calculated as 0.862 and DeNOx efficiency was 75.9%.

• Korea Trade Review
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• v.44 no.1
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• pp.269-283
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• 2019

Due to environmental issues such as global warming, the importance of renewable energy is growing. Solar Power System is one of the most growing eco-friendly energy industries in the world, but Korea's solar energy industry faces fierce competition due to the trade regulations and changes in energy related laws in the major markets such as the U.S., EU and China. Therefore, Korea needs to diversify its export markets towards emerging markets. This paper analyzed 162 countries in the world and developed a model to measure how promising the countries are. GSMI(Grid connected Solar Market Index) and OSMI(Off-grid Solar Market Index) are invented based on the models. By using the developed model and the data of 162 countries over the 15-year period from 2000 to 2014, the foreign markets are ranked for searching the export market. According to the analysis, China, Japan, U.S, India and Taiwan ranked first to fifth in GSMI and OSMI ranking, which were followed by China, India, Bangladesh, Philippines and Afghanistan. The model developed through this research is expected to provide a more reasonable and scientific approach to the advancement of the Korean solar energy industry into overseas markets.

• International journal of advanced smart convergence
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• v.11 no.2
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• pp.171-184
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• 2022

The purpose of this paper is output oriented, in order to maximize the output level of sustainable development efficiency of foreign trade in western China with limited input. This paper adopts the relevant input-output indicators of sustainable foreign trade development of 11 provinces and cities in western China from 2016 to 2020, and uses DEA model to measure their technical efficiency, pure technical efficiency and scale efficiency. Malmquist index was used to calculate the total factor productivity change index of each province in western China from 2016 to 2020. We found that, on the whole, the average values of technical efficiency, pure technical efficiency and scale efficiency of provinces and cities in western China from 2016 to 2020 are greater than 0.8, indicating that the western region has high technical efficiency, relatively high management and institutional level and high existing scale level. Scale efficiency is lower than pure technical efficiency on the whole, indicating that the current sustainable development efficiency of foreign trade in western China is mainly limited by its scale level. The technological progress index is higher than the technological efficiency change index, indicating that the total factor productivity of the sustainable development of foreign trade in western China is mainly driven by technological progress and more influenced by external factors. We think the conclusion of this study can provide important reference information for the sustainable development of foreign trade of provinces and cities in western China.

• Journal of Forest and Environmental Science
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• v.24 no.3
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• pp.155-158
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• 2008

Site index is the essential tool for forest management to estimate the productivity of forest land Generally, site index equation is developed and used by relationship between stand age and dominant tree heights. However, there is a limit to use the site index equation in the application of variable ages, environmental influence, and estimation of site index for unstocked land. Therefore, it was attempted to develop a new site index equations based on various environmental factors including site and topographical variables. This study was conducted to develop regional site index equations based on the relationship between site index and soil factors for Pinus densiflora. Environmental factors that obtained from GIS application, were selected by stepwise-regression. Site index Equation was estimated by multiple regression from selected factors. Four environmental factors were selected in the final site index equations by stepwise regression. It was observed that coefficients of determination for site index equations were ranged from 0.34 which seem to be relatively low but good enough for estimation of forest stand productivity. The site index equations developed in this study were also verified to be useful by three evaluation statistics such as model's estimation bias, model's precision and mean square error type of measure.

• Korean Journal of Agricultural and Forest Meteorology
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• v.8 no.2
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• pp.97-106
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• 2006

Site index is an essential tool to estimate forest productivity. Generally, a site index equation is developed and used from the relationship between stand age and dominant tree heights. However, there is a limit to the use of the site index equation in the application of variable ages, environmental influence, and estimation of site index for the unstocked forest. Therefore, it has been attempted to develop a new site index equation based on various environmental factors including site, climate, and topographical variables. This study was conducted to develop a site index equation based on the relationship between site index and environmental factors for the species of Pinus koraiensis in Yangpyung-Gun, Gyunggi Province. The influence of climatic factors (temperature and solar irradiation ratio), topographical factors (elevation, slope, ratio of slope to valley and aspect) and soil profiles (soil depth by layer and soil consistency) on site index were evaluated by multiple regression analysis. Five environmental factors were selected in the final site index equation for Pinus koraiensis. The site index equation developed in this study was also verified by three evaluation statistics: model's estimation bias, model's precision, and mean square error of measurement. Based on the site index equation, the number of productive areas for Pinus koraiensis were estimated by applying GIS technique to digitized forest maps. In addition, the distribution of productive areas was compared with the areas of current distribution of Pinus koraiensis. It is expected that the results obtained in this study could provide valuable information about the amount and distribution of productive areas for Pinus koraiensis reforestation.

• Journal of Information Technology Services
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• v.12 no.4
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• pp.187-204
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• 2013

In this study, we developed a comprehensive model to measure the National Information Security Level based on PRM framework. The proposed model reflected a rapidly changing technology environments such as social network service, mobile devices, and etc. This new model consists of three layers:Infrastructure Layer, the Action Layer and the Performance Layer, and there are 16 sub-indexes under the 3 layers. To develop new model and sub-indexes for measuring the National Information Security Level, much amounts of documents related to security indexes or deliberation criteria and security guidelines from international organization were reviewed and then most probable index pool were composed. The Index pool were verified by expert group consisting of professors and specialists. Through five times of screening and having an evaluation review, 16 sub-indexes were deduced and then Delphi and AHP have been conducted to obtain validity and objectiveness of the indexes. Thus the new proposed national information security index will show more exact national information security level and we expect that the indexes give much implications for establishing information protection policy.

• Journal of Korean Society for Quality Management
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• v.35 no.4
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• pp.26-37
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• 2007

The demand of ubiquitous home network system is rapidly increasing in Korea as each construction enterprise makes a huge effort to introduce it to apartment complex. However, the design of home network system is rather technology oriented than the customer focused. Lack of knowledge about customer needs is an obstacle in spreading the ubiquitous home network system to the market regardless of technology development. In this paper, we propose a HCSI(customer satisfaction index for home network system) using an SEM(structural equation model) where structural relationship among several factors influential on users' satisfaction is considered. This model enables to calculate the satisfaction index for target customer group so that one can provide necessary feedback information for improvement of the home network system used for each group.

• ETRI Journal
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• v.30 no.5
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• pp.634-643
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• 2008

One of the ubiquitous technology fields that have received the most attention recently from technology communities worldwide is mobile radio frequency identification (RFID). Mobile handsets loaded with RFID readers enable the identification and retrieval of information on RFID tagged objects. In Korea, a variety of mobile RFID services are currently being piloted, and their commercial roll-out looks imminent. The goal of this study is to propose, ahead of the commercial launch of mobile RFID services, a customer satisfaction index (CSI) model for this service category and to then measure the CSI to derive practical implications for their providers and pointers related to the improvement of service. A web survey was conducted on Korean mobile phone subscribers who had participated in a mobile RFID pilot program. Using the results of this survey, we tested the CSI model and its hypotheses by employing a partial least-squares-based structural equation model analysis and calculated the index. We further conducted an importance-performance analysis in order to provide insights that may be useful for improving the quality of mobile RFID services.

• Journal of KIISE:Databases
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• v.31 no.1
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• pp.48-60
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• 2004

XML documents consist of elements that are basic units of information. When the structure of XML documents is changed dynamically, we need to update structure information efficiently without changing the information of the index structure for fast retrieval. In this paper, we propose a dynamic indexing model scheme that updates the index structure in real time as the structure of XML documents is changed by insertion and deletion of elements. Our dynamic indexing model consists of a structure information representation method and a dynamic index structure. The structure information representation method supports various types of structure retrievals. Our dynamic index structure processes various structural queries efficiently. We show through various experiments that our method outperforms existing ones in processing various types of queries such as content based queries, structural queries and hybrid queries.