• Journal of Korea Water Resources Association
• /
• v.51 no.11
• /
• pp.1011-1020
• /
• 2018

This study aims to develop a drought monitoring scheme based on groundwater which can be exploit for water supply under drought stress. In this context, groundwater level can be used as a proxy for better understanding the temporal evolution of drought state. First, kernel density estimator is presented in the monthly groundwater level over the entire national groundwater stations. The estimated cumulative distribution function is then utilized to map the monthly groundwater level into the standardized groundwater level index (SGI). The SGI for each station was eventually converted into the index for major cities through the Thiessen polygon approach. We provide a drought classification for a given SGI to better characterize the degree of drought condition. Ultimately, we conclude that the proposed monitoring framework enables a more reliable estimation of the drought stress, especially for a limited water supply area.

• Journal of Navigation and Port Research
• /
• v.30 no.8 s.114
• /
• pp.657-662
• /
• 2006

This study proposes the introduction of management assessment system on the remote island route passenger companies in a way of stimulating the companies to make sustained efforts on management improvement, and come up with the ways of management assessment index and management assessment methods by using the AHP scheme. These indices are organizes in three categories. The main category is consisted of responsible management part, management an control part, business operation part and customer satisfaction part, and the intermediary category has the 15 items including the efforts for responsible management, and the sub category is consisted of 44 items including the management vision of executive and participation of enterprise in responsible management, and others. The scoring of these indices is the result of scoring by calculating the added weight for each category by using the AHP scheme that it is considered as needed for the scoring adjustment for each standard of assessment index by the adjustment of added weight for categories with the consideration of shipping company operation and shipping characteristics while undertaking the actual affairs.

• Journal of the Korean Data and Information Science Society
• /
• v.28 no.2
• /
• pp.327-337
• /
• 2017

In this study we compared three models for small area estimation, Fay-Herriot, Hierarchical Bayses model and spatio-temporal model about charter, monthly rent price index. Charter, monthly rent price of Korea are important issue in these days. Because housing type rapidly changes from self to charter and monthly rent. The accuracy of the estimation was checked on four scales, that is ARB, ASRB, AAB, ASD. In this result, the spatio-temporal model among applied models has most optimal scales about small area estimation of charter and monthly rent index.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• 2006.06b
• /
• pp.131-136
• /
• 2006

This study proposes the introduction of management assessment system an the remote island route passenger companies in a way of stimulating the companies to make sustained efforts on management improvement, and come up with the ways of management assessment index and management assessment methods by using the AHP scheme. These indices are organizes in three categories. The main category is consisted of responsible management part, management an control part, business operation part and customer satisfaction part, and the intermediary category has the 15 items including the efforts for responsible management, and the sub category is consisted of 44 items including the management vision of executive and participation of enterprise in responsible management, and others. The scoring of these indices is the result of scoring by calculating the added weight for each category by using the AHP scheme tint it is considered as needed for the scoring adjustment for each standard of assessment index by the adjustment of added weight for categories with the consideration of shipping company operation and shipping characteristics while undertaking the actual affairs.

• Journal of KIISE:Databases
• /
• v.30 no.4
• /
• pp.420-428
• /
• 2003

XML is a data-oriented language to represent all types of documents including web documents. By means of the advent of XML-based document generation tools and grow of proprietary XML documents using those tools and translation from legacy data to XML documents at an accelerating pace, we have been gotten a large amount of differently-structured XML documents. Therefore, it is more and more important to retrieve the right documents from the document set. But, previous works on XML have mainly focused on the storage and retrieval methods for a large XML document or XML documents had a same DTD. And, researches that supported the structural difference did not efficiently process path queries on the document set. To resolve the problem, we suggested a new inverted index mechanism using RDBMS and proved it outperformed the previous works. And especially, as it showed the higher efficiency in indirect containment relationship, we argues that the index structure is fit for the differently-structured XML document set.

• Journal of Internet Computing and Services
• /
• v.10 no.6
• /
• pp.1-6
• /
• 2009

In this paper, we propose an energy efficient index scheme for Nearest Neighbor queries, specially designed for mobile P2P environments. we propose a PMBR (P2P Minimum Boundary Rectangle) index that provides the client with the ability of selective contacting and tuning from other nodes. The mobile client is able to identify whether or not the neighbor nodes have the desired information by accessing PMBR. Thus, the client immediately switches to change to another node's broadcast channel if the index does not contain the desired information. Furthermore, the client is able to predict the arrival time of the desired data items and only needs to tune into the broadcast channel when the requested data items arrives, by first accessing PMBR. Thus, the mobile client can stay in power save mode most of time, and tune into the broadcast channel only when the requested data items arrive. Experiments are conducted to evaluate the performance of the proposed scheme. Comprehensive experiments illustrate that the proposed scheme is more efficient than the previous techniques in terms of energy consumption.

• Journal of Korea Multimedia Society
• /
• v.9 no.11
• /
• pp.1421-1434
• /
• 2006

Spatial data warehouses provide analytical information for decision supports using SOLAP (Spatial On-Line Analytical Processing) operations. Many researches have been studied to reduce analysis cost of SOLAP operations using pre-aggregation methods. These methods use the index composed of fixed size nodes for supporting the concept hierarchy. Therefore, these methods have many unused entries in sparse data area. Also, it is impossible to support the concept hierarchy in dense data area. In this paper, we propose a dynamic pre-aggregation index method based on the spatial hierarchy. The proposed method uses the level of the index for supporting the concept hierarchy. In sparse data area, if sibling nodes have a few used entries, those entries are integrated in a node and the parent entries share the node. In dense data area, if a node has many objects, the node is connected with linked list of several nodes and data is stored in linked nodes. Therefore, the proposed method saves the space of unused entries by integrating nodes. Moreover it can support the concept hierarchy because a node is not divided by linked nodes. Experimental result shows that the proposed method saves both space and aggregation search cost with the similar building cost of other methods.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.28 no.3B
• /
• pp.283-296
• /
• 2008

The Urban Stream Assessment Technique (USAT) was suggested to give information about present urban stream condition. Domestic and foreign stream evaluation methods were analyzed and some streams were previously investigated to decide evaluation factors that could evaluate stream condition and have concern with characteristics and flood control of urban stream. The USAT consisted of three steps. High step has three characteristics concerned with functions of stream such as flood risk, stream, and ecology. In middle step, three characteristics were subdivided by ten features to describe changes and degradations of urban stream. Low step consisted of fifty three factors that explain the present condition of ten features. A survey of river experts was conducted to reflect weight among characteristics and features. The weights were calculated by analytic hierarchy process(AHP). The USAT was carried out to check over application of that in Suwon, Anyang, and Joongrang stream. The results of stream evaluation were expressed by factor index, feature index, characteristic index, total index, and evaluation grade. The results of the USAT were useful to realize changed and degraded areas. It is expected that the USAT can be used as base investigation for restoring and managing urban streams.

• Journal of Korean Library and Information Science Society
• /
• v.40 no.3
• /
• pp.137-156
• /
• 2009

This study has analyzed the uncontrolled index terms in the theological journal, which were assigned by the authors and the LCSH subject headings in their form and meaning, compared to the standards of index terms and proposed much more sophisticated indexing system. In the uncontrolled index terms, noun phrases and compound terms are analyzed, this study found that indexers have to have theological knowledge and indexing techniques in order to assign more precise index terms. In the LCSH, unnecessary index terms and parenthetical qualifiers were analyzed. As a result of it, this study identified that the problems of inconsistency and errors raised from the basic index structure of LCSH.

• The Journal of Information Systems
• /
• v.18 no.3
• /
• pp.351-373
• /
• 2009

An index fund is a collective investment scheme that aims to replicate the movements of an index of a specific financial market regardless of market conditions. An index fund is a popular investment alternative because it is much cheaper to run than an active fund and it performs better than actively managed funds. This paper illustrates the usefulness of wavelet analysis in constructing an index fund. The wavelet analysis can decompose the time series data in frequency domain as well as in time domain. The major findings of this paper are as follows. First, the beta coefficient that represents the systematic risk has the scale dependent property. This result can provide important information to the investors with various investment time frequency. Investors can use the betas corresponding to their investment frequencies among the various scale betas estimated by wavelet analysis. Second, we can find the usefulness of wavelet analysis in constructing index fund because the wavelet technique gives less tracking error(difference between the index performance and the index fund performance) than the traditional constructing techniques. The result of this study implies that the wavelet techniques can be an important analytic method to the other financial markets such as option market, futures market, bond markets and currency market.