• Journal of KIISE:Databases
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• v.37 no.3
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• pp.146-164
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• 2010

Due to an increasing volume of XML data, it is considered prudent to store XML data on an industry-strength database system instead of relying on a domain specific application or a file system. For shredded XML data stored in relational tables, however, it may not be straightforward to apply existing algorithms for twig query processing, since most of the algorithms require XML data to be accessed in a form of streams of elements grouped by their tags and sorted in a particular order. In order to support XML query processing within the common framework of relational database systems, we first propose several bitmap indexes and their strategies for supporting holistic twig joining on XML data stored in relational tables. Since bitmap indexes are well supported in most of the commercial and open-source database systems, the proposed bitmapped indexes and twig query processing strategies can be incorporated into relational query processing framework with more ease. The proposed query processing strategies are efficient in terms of both time and space, because the compressed bitmap indexes stay compressed during data access. In addition, we propose a hybrid index which computes twig query solutions with only bit-vectors, without accessing labeled XML elements stored in the relational tables.

• Journal of KIISE:Information Networking
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• v.30 no.4
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• pp.559-571
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• 2003

ENUM(tElephon NUmbering Mapping) is protocol that brings convergence between PSTN Networks and IP Networks using a unique worldwide E.164 telephone number as an identifier between different communication infrastructure. The mechanism provides a bridge between two completely different environments with E.164 number; IP based application services used in PSTN networks, and PSTN based application services used in IP networks. We propose a new way to organize and handle ENUM Tier 2 name servers to improve performance at the name resolution process in ENUM based application service. We build an ENUM based network model when NAPTR(Naming Authority PoinTeR) resource record is registered and managed by area code at the initial registration step. ENUM promises convenience and flexibility to both PSTN and IP users, yet there is no evidence how much patience is required when users decide to use ENUM instead of non-ENUM based applications. We have estimated ENUM response time, and proved how to improve performance up to 3 times when resources are managed by the proposed mechanism. The proposition of this thesis favorably influences users and helps to establish the policy for Tier 2 name server management.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.11
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• pp.1592-1597
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• 2015

In this study, we developed a fiber-optic temperature sensor (FOTS) based on a silicone oil and an optical time domain reflectometer (OTDR) to apply the measurement of a coolant leakage in the nuclear power plant. The sensing probe of the FOTS consists of a silicone oil, a stainless steel cap, a FC terminator, and a single mode optical fiber. Fresnel reflection arising at the interface between the silicone oil and the single mode optical fiber in the sensing probe is changed by varying the refractive index of the silicone oil according to the temperature. Therefore, we measured the optical power of the light signals reflected from the sensing probe. The measurable temperature range of the FOTS using a Cu-coated silica fiber is from $70^{\circ}C$ to $340^{\circ}C$ and the maximum operation temperature of the FOTS is sufficient for usage at the secondary system in the nuclear power plant.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.276-276
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• 2010

Localized surface plasmon resonance (LSPR) has been explored recently as a promising approach to increase energy conversion efficiency in photovoltaic devices, particularly for thin film hydrogenated amorphous silicon (a-Si:H) solar cells. The LSPR is frequently excited via an electromagnetic (EM) radiation in proximate metallic nanostructures and its primary con sequences are selective photon extinction and local EM enhancement which gives rise to improved photogeneration of electron-hole (e-h) pairs, and consequently increases photocurrent. In this work, high-dielectric-constant (k) $ZrO_2$ (refractive index n=2.22, dielectric constant $\varepsilon=4.93$ at the wavelength of 550 nm) is proposed as spacing layer to enhance the LSPR for application to the thin film silicon solar cells. Compared to excitation of the LSPR using $SiO_2$ (n=1.46, $\varepsilon=2.13$ at the wavelength of 546.1 nm) spacing layer with Au nanoparticles of the radius of 45nm, that using $ZrO_2$ dielectric shows the advantages of(i) ~2.5 times greater polarizability, (ii) ~3.5 times larger scattering cross-section and ~1.5 times larger absorption cross-section, (iii) 4.5% higher transmission coefficient of the same thickness and (iv) 7.8% greater transmitted electric filed intensity at the same depth. All those results are calculated by Mie theory and Fresnel equations, and simulated by finite-difference time-domain (FDTD) calculations with proper boundary conditions. Red-shifting of the LSPR wavelength using high-k $ZrO_2$ dielectric is also observed according to location of the peak and this is consistent with the other's report. Finally, our experimental results show that variation of short-circuit current density ($J_{sc}$) of the LSPR enhanced a-Si:H solar cell by using the $ZrO_2$ spacing layer is 45.4% higher than that using the $SiO_2$ spacing layer, supporting our calculation and theory.

• Journal of Korea Water Resources Association
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• v.32 no.6
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• pp.741-749
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• 1999

This study is to develop a method of measuring the soil water concentration by using TDR, which is based on the relationships between the bulk soil electrical conductivity of soil and the reflected wave of TDR. The proposed monitoring method is combined with two important relationships. One is that between the bulk soil electrical conductivity and the solute concentration, which is known to be linear at a constant volumetric soil water content and the other is that between the relative bulk soil electrical conductivity and the water content at a constant concentration. Some formulas have been proposed to solve the second relationship, but a new formula and the critical water content are proposed to improve the accuracy of measurement. This proposed formula estimates the relative bulk soil electrical conductivity for water contents which is divided to two regions, linear and nonlinear, by the critical water content. As the result of the comparison with other formulas, the proposed formula is proved to be superior to other formulas and to be an available method to apply to the unsaturated transient solute transport.

• Journal of Korea Water Resources Association
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• v.32 no.6
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• pp.751-762
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• 1999

In this study, a 1-D laboratory experiment was conducted to investigate the characteristics of transient unsaturated solute transport by using two kinds of soils of which properties were known by test. Especially the TDR method which is proposed in this study was used to measure water content and solute concentration. As results, in the transient flow, the wetting front moves down rapidly, and the distribution of solute concentration near the wetting front showed the similar type of the water content distribution(semi-bell type). A numerical model HYDRUS was used to compare with the experimental results. Numerical results for the water movement are similar to experimental result. However, numerical results of the distribution of solute concentration are more scattered than experimental results. It means that measured dispersivity, numerical dispersion, adsorption coefficient, and soil sample size etc. should be considered in order to determine the dispersivity used in the numerical model. The present measuring method was proved to be superior to other formula and to be an available method to apply to solute transport test. The measuring error of the developed method is estimated smaller than 10% while water content is larger than 0.15.

• Journal of the Korean Association of Geographic Information Studies
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• v.5 no.1
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• pp.58-68
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• 2002

Recently as recognition to prevent nature disasters is reaching the climax, the most important job of government official is to provide information related to the prevention of nature disasters through the Web and to bring notice to prevent disaster under people. Especially, if the case of daily forest fire hazard index is provided within visualization on Web, people may have more chances to understand about forest fire and less damages by large scale of forest fire. Forest fire hazard index presentation system developed in this paper presents daily forest fire hazard index on map visually also provides the information related to it in text format. In order to develop this system, CBDP(Component Based Development Process) is proposed in this paper. This development process tries to emphasize the view of reusability so that it has lifecycle which starts from requirement and domain analysis and finishes to component generation. Moreover, The concept of this development process tries to reflect component based method, which becomes hot issue in software field nowadays. In the future, the component developed in this paper may be possibly reused in other Web GIS application, which has similar function to it so that it may take less cost and time to develop other similar system.

• Cross-Cultural Studies
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• v.33
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• pp.143-169
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• 2013

Recently, because of the danger and damages that following the steady development of scientific technologies, natural science is faced with many humane and ethical problems. So it is asserted the interdisciplinary with social and human science. However, it comes commonly that the ethical issues such as world view and one's view of life caused the development of sociology, especially development of the market economy. But in many cases, the interdisciplinary can be useful for widen the view of scholars. The interdisciplinary is actually connected with the problems of philosophy, and located in that domain. In this case, this is noticed as a model to the philosophers in 18th century, especially Denis Diderot. Diderot published De $l^{\prime}interpr{\acute{e}}tation$ de la nature during editing the Encyclopedia, from there he picked out the contents from piles of documents of Encyclopedia. Even though the contents or opinions of De $l^{\prime}interpr{\acute{e}}tation$ de la nature are inaccuracy or erroneous, it shows that how human-social science and natural science encountered. Diderot studied mathematics and then Diderot accepted to the natural science proposal, he approaches philosophy with translate English books to the French. Next he understood natural science by reading Buffon and Maupertuis, and during working for Encyclopedia, he possessed his knowledge that he can claim his opinion to other scholars. However in this De $l^{\prime}interpr{\acute{e}}tation$ de la nature, Diderot who sometimes rebutted other scholars' theory and demonstration, tried to build a philosophy on metaphysics in order to it was important for himself that he imposed the methods of science and importance of experience. Anyhow, this De $l^{\prime}interpr{\acute{e}}tation$ de la nature cause consider the recognition of Diderot in the field of natural science, and is suggested as a model about his Nature. This mean that it is an expression of his philosophy, and the content is found from natural philosophy and empirical philosophy. Like giving these attache the importance of method study for science and technique, these are targeted the promotion of popularization of natural-science and scientific-technology. Also it advocates fulfilling from reasonable philosophy to empirical philosophy. Therefore, the philosophy which was speculative and abstracted became his philosophy which was writing the meaning, as waiting the discovery of science. And at that time, the humanities made interdisciplinary with natural science.

• Cross-Cultural Studies
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• v.44
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• pp.373-391
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• 2016

Since the 2000's, interest toward Africa in Korea has increased rapidly. Korea's interest in Africa began in the second half of the 1960's. However, this interest in the 1960's was motivated by political and diplomatic necessity at the time rather than the needs of indigenous groups in Africa. Korea had to oppose North Korea's diplomatic expansion in Africa to gain the support of international organizations like the United Nations. This interest in Africa motivated by diplomatic needs vanished quickly after the end of the cold war in the 1990's. Authentic Korean interest in Africa began to emerge in the 2000's. Korea's rising international status based on economic development led to a natural interest in Africa, which was the last frontier on earth. As a result, African studies in Korea increased significantly after 2010. The increase in the number of theses, articles and books was remarkable from 2010-2016, in comparison with 1957-2010. In spite of the increase in the quantity of thesis, articles, and books, the problem with Korea's African studies is above all, its preponderance. Over 75% of thesis and 70% of articles are concentrated in the domain of politics and economics. This reflects the fact that Korea's interest in Africa is based on short term political and economic interest, indicating that Korea's African studies did not deviate from the rudimentary phase in its quantity and quality. Another problem with Korea's African studies is the lack of integration of different types of research. African studies in Korea has three components, government funded research centers, university laboratories and individual researchers. The government funded research centers focus on the overview of African nations and their political and economic information. University laboratories mainly perform research on the theoretical aspects of politics, economics, human sciences and culture in Africa. Individual researchers are concerned with various categories. However, these three groups have failed to achieve a synergic effect on African studies in Korea and most of the research on Africa does not extend beyond each academic area. To overcome this problem, first of all, a live exchange may be necessary between domestic researchers.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.11
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• pp.594-603
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• 2018

Recently, according to the development of measurement techniques, it has become possible to take complicated and time-consuming field measurements in a simple and convenient manner. In this background, this study estimated the tension of cables under ambient vibration using minimized measurement and signal processing. The VBDM using video-only by low-cost equipment was used as a minimized measurement. An estimation of the natural frequency using the mirror frequency concept was also proposed to solve the shortage of frequency band in this case. Furthermore, the FDD method was adopted for a natural frequency estimation in the ambient vibration related to field application. Experimental studies using a cable-stayed bridge model were carried out to examine the properties of the mirror frequency and the applicability of FDD with the proposed minimized system. The results showed that FDD for ambient vibration also works properly in an estimation of the natural frequency using the minimized system. In addition, the mirror frequency concept can allow a high natural frequency estimation even in a distorted signal by low-speed recording, which can overcome the limit of the minimized system. Overall, the proposed minimized system can be effective for the tension estimations of a cable under ambient vibration.