• Journal of Computing Science and Engineering
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• v.4 no.4
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• pp.276-290
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• 2010

The join operator is fundamental in relational database systems. Evaluating join queries on large tables is challenging because records need to be efficiently matched based on a given key. In this work, we analyze join queries in SQL with large tables in which a foreign key may be null, invalid or valid, given a referential integrity constraint. We conduct an extensive join performance evaluation on three DBMSs. Specifically, we study join queries varying table sizes, row size and key probabilistic distribution, inserting null, invalid or valid foreign key values. We also benchmark three well-known query optimizations: view materialization, secondary index and join reordering. Our experiments show certain optimizations perform well across DBMSs, whereas other optimizations depend on the DBMS architecture.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2007.05a
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• pp.60-63
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• 2007

Light is a critical element for people to live and do creative activities in residential buildings. Especially, light in dinning room is the most important thing for psychological and emotional effects but people are living under the poor light environment. Most people even isn't well aware of good lighting environment. Also, the domestic lighting designers just follow the Korean Standards illuminance but it isn't appropriate to our cultural and social sides. This study investigates illuminance and color temperature of dining tables, and also analyzed the results of those in actual residential buildings.

• Journal of Korean Library and Information Science Society
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• v.40 no.2
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• pp.5-26
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• 2009

The purpose of this study aims to provide possible suggestions for the improvement KDC 5th ed. as a system. After analyzing and evaluating various devices of KDC 5th ed. such as schedules, common auxiliary tables, internal tables(omitted), notes, relative index, precedence order(omitted), alternatives, manual(omitted) and relocated table(omitted), suggestions for the improvement were proposed. If above suggestions are adopted, effective literature classification scheme which is suited to domestic circumstances will be certainly prepared.

• The Korean Journal of Applied Statistics
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• v.7 no.1
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• pp.69-74
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• 1994

Kim (1992) derived influence functions of rows and columns on the eigenvalues obtained in correspondence analysis (CA) of two-way contingency tables. As in principal component analysis, the eigenvalues are of great importance in CA. The goodness of a two dimensional correspondence plot is determined by the ratio of the sum of the two largest eigenvalues to the sum of all the eigenvalues. By investigating those rows and columns with high influence, a correspondence plot may be improved. In this paper, we extend the influence functions of CA to multiple correspondence analysis (MCA), which is a CA of multi-way contigency tables. An explicit formula of the influence function is given.

• Nuclear Engineering and Technology
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• v.35 no.6
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• pp.581-595
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• 2003

Transport lattice codes require the resonance integral tables for the resonant nuclides where the resonance integral is a function of the background cross section and can be prepared through a special program solving the slowing down equation. In case the cross section libraries do not include the resonance integral table for the resonant nuclides, the computational prediction produces a large error. We devised a new method using a Monte Carlo calculation for the effective resonance cross sections to solve this problem provisionally. We extended this method to obtain the resonance integral table for general purpose. The MCNP code is used for the effective resonance integrals and the LIBERTE code for the effective background cross sections. We modified the HELIOS library with the effective cross sections and the resonance integral tables obtained by the newly developed Monte Carlo method, and performed sample calculations using HELIOS and LIBERTE. The results showed that this method is very effective for the resonance treatment.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.767-772
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• 2005

The Internet is a packet switched network which offers best-effort service, but current IP network provide enhanced services such Quality of Services, Virtual Private Network (VPN) services, Distribute Firewall and IP Security Gateways. All such services need packet classification for determining the flow. The problem is performing scalable packet classification at wire speeds even as rule databases increase in size. Therefore, this research offer packet classification algorithm that increase classifier performance when working with enlarge rules database by rearrange rule structure into Bitmap Intersection Lookup (BIL) tables. It will use packet's header field for looking up BIL tables and take the result with intersection operation by logical AND. This approach will use simple algorithm and rule structure, it make classifier have high search speed and fast updates.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.454-458
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• 2001

A new model utilizing a transfer function was proposed in the previous paper for analizing motion errors of hydrostatic tables. Validity of the proposed method was theoretically verified as the calculated motion errors were compared with the results by conventional multi pad method. In this paper, relationship between form error of rail and motion errors of hydrostatic table is analized theoretically in order to comprehand so-called 'averaging effect of oil film'. Experiments on the motion errors of hydrostatic table is conducted with 3 different rails, and the results are compared with the results calculated by Transfer Function Method. The results show good agreement. From the results, it is verified that TFM is very effective to analize the motion errors of hydrostatic table.

• Journal of the Korean Data and Information Science Society
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• v.18 no.1
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• pp.185-194
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• 2007

The information of covariates are available to do fully efficient fractional imputation(FEFI). The new method, FEFI with logistic regression is proposed to construct complete contingency tables. Jackknife method is used to get a standard errors of log-odds ratio from the completed table by the new method. Simulation results, when covariates have more information about categorical variables, reveal that the new method provides more efficient estimates of log-odds ratio than either multiple imputation(MI) based on data augmentation or complete case analysis.

• The Journal of Information Systems
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• v.18 no.3
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• pp.327-349
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• 2009

Traditional keyword-based searching methods suffer from low accuracy and high complexity due to the rapid growth in the amount of information. Accordingly, many researchers attempt to implement a so-called semantic search which is based on the semantics of the user's query. Semantic information can be described using a semantic modeling language, such as Topic Map. In this paper, we propose a new method to map a topic map to a traditional Relational Database (RDB) without any information loss. Although there have been a few attempts to map topic maps to RDB, they have paid scant attention to handling multi-role topics. In this paper, we propose a new storage structure to map multi-role topics to traditional RDB. The proposed structure consists of a mapping table, role tables, and content tables. Additionally, we devise a query translator to convert a user's query to one appropriate to the proposed structure.

• Proceedings of the Korean Geotechical Society Conference
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• 2006.03a
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• pp.1120-1125
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• 2006

Larger area will be constructed in a harbor land and container terminal which are constructed in reclaimed land using the dredged materials. Soil improvement work is to be carried out including constructibility, in which is monitoring devices, measuring frequency, installations etc. The ground water tables in the reclaimed area are affected by the several factors which are design reclamation level, consolidation settlement, remaining surcharge pressure and remaining excess pore water pressure. The plan wii be drawn up in which monitoring results for the ground water tables are capable to provide the reliable ground water table when designers and civil engineers construct the harbor structures considering constructibility.