• Journal of KIISE:Databases
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• v.32 no.3
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• pp.285-296
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• 2005

In mobile distributed systems the data on the air can be accessed by a lot of mobile clients. And, we need an indexing scheme in order to energy-efficiently access the data on the wireless broadcast stream. In conventional indexing schemes, they use the values of primary key attributes and construct tree-structured index. Therefore, the conventional indexing schemes do not support content-based retrieval queries such as partial-match queries. In this paper we propose an indexing scheme, called B2V-Tree, which supports partial match queries on wireless broadcast data stream. For this purpose, we construct a tree-structured index which is composed of bit-vectors, where the bit-vectors are generated from data records through multi-attribute hashing.

• Journal of KIISE:Computing Practices and Letters
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• v.9 no.5
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• pp.530-540
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• 2003

As the amount of information on Internet sites increases, it becomes more necessary to provide information in efficient ways. However, information search methods based on Boolean combination of keywords that most sites provide are difficult to express user's intention adequately so that there are numerous unexpected search results. This paper proposes a conversational agent that provides users with accurate information in a friendly manner through natural language conversation. The agent recognizes user's intention by applying finite state automata to natural language queries, utilizes the intention for structured pattern matching with response knowledge, and thus provides answers that are robust against changes in word order and consistent with the user's intention. To show its practical utility, the agent is applied to the problem of introducing a Web site. The results show that the conversational agent has the ability to provide accurate and friendly responses.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.1B
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• pp.8-14
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• 2000

This paper analyzes and accesses the gain of optically pumped surface-normal MQW optical amplifiers. The proposed amplifiers have the advantage of polarization independence, high coupling efficiency to and from optical fibers, and flexibility of operating wavelength. We analyzed the gain characteristics of 100 - 200-period MQWs and verified the dependence of a strained lattice and selective doping. Theoretical analysis of such MQWs showsa single-pass gain of 3 dB with broad operation bandwidth. A single-pass gain of 2.6 dB is obtained experimentally in an InGaAs/InGaAlAs MQW amplifier, which is compared with calculations. The use of Fabry-Perot interferometer (FPI) structure in an optical amplifier is a useful way to increase the gain, but causes a problem of narrow operation bandwidth when the single-pass gain is low. Therefore, a single-pass gain above 2to 3 dB is a prerequisite to achieve both a high gain and moderate operation bandwidth in FPI-structured opticalamplifiers. We have designed an FPI-structured surface-normal optical amplifier both with a high gain of broad operation bandwidth of 4.6mm, when a single-pass gain is 3 dB.

• Applied Chemistry for Engineering
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• v.10 no.6
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• pp.832-837
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• 1999

Stability of a cathode material was determined by Tafel plot in 1 M LiOH solution. The stabilized $LiM_xMn_{2-x}O_4$ (x=0.05~0.1) electrode resulted in overpotential of 0.13~0.15 mV at 100 mA. This overpotential was 0.05 mV lower than that of the spinel structured $LiMn_2O_4$ electrode. Conductivity test at various potentials showed that the conductivity of $LiM_xMn_{2-x}O_4$ was higher than that of the spinel structured $LiMn_2O_4$ and the bulk resistance of $LiM_xMn_{2-x}O_4$ due to the dissolution of $Mn^{2+}$ was lowered.

• Journal of radiological science and technology
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• v.38 no.4
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• pp.483-489
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• 2015

DICOM (Digital Imaging and Communications in Medicine) standards are generally introduced as de facto and de jure standards in modern medical imaging devices to store and to transmit medical image information. DICOM Dose Structured Report (DICOM dose SR) is implemented to report radiation exposure information in image acquiring process. and DIOCM Modality Performed Procedure Step (DICOM MPPS) is also partly used to report this exposure with the information in its DICOM tag. This article is focused on three type of radiation exposure information of DICOM standards, 1) DICOM dose SR, 2) DICOM MPPS and 3) Radiation Exposure Monitoring(REM) profile by Integrating the Healthcare Enterprise(IHE), to study on radiation exposure reporting. Healthcare facility and its staff of medical imaging related to radiation exposure should have a deep understanding of radiation exposure, and it required a standards to enhance the quality control of medical imaging and the safety of patients and staffs. Staff member have to pay attention on radiation exposures and controling processes from the purchasing stage of X-ray devices.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.337-337
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• 2012

Dye sensitized solar cell (DSSC) having high efficiency with low cost was first reported by Gr$\ddot{a}$tzel et al. Many DSSC research groups attempt to enhance energy conversion efficiency by modifying the dye, electrolyte, Pt-coated electrode, and $TiO_2$ films. However, there are still some problems against realization of high-sensitivity DSSC such as the recombination of injected electrons in conduction band and the limited adsorption of dye on $TiO_2$ surface. The surface of $TiO_2$ is very important for improving hydrophilic property and dye adsorption on its surface. In this paper, we report a very efficient method to improve the efficiency and stability of DSSC with nano-structured $TiO_2$. Atmospheric plasma system was utilized for nitrogen plasma treatment on nano-structured $TiO_2$ film. We confirmed that the efficiency of DSSC was significantly dependent on plasma power. Relative in the $TiO_2$ surface change and characteristics after plasma was investigated by various analysis methods. The structure of $TiO_2$ films was examined by X-ray diffraction (XRD). The morphology of $TiO_2$ films was observed using a field emission scanning electron microscope (FE-SEM). The surface elemental composition was determined using X-ray photoelectron spectroscopy (XPS). Each of plasma power differently affected conversion efficiency of DSSC with plasma-treated $TiO_2$ compared to untreated DSSC under AM 1.5 G spectral illumination of $100mWcm^{-2}$.

• Journal of Educational Research in Mathematics
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• v.27 no.4
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• pp.701-725
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• 2017

Students need to have opportunities to share their ideas with peers by taking part in the conversation voluntarily that is, by persuading others and reflecting the consequences. Recognizing the importance of this point, this study intended to examine students' argumentation occurring in the process of performing tasks in the math classroom. Also, it tried to explore the types of the argument that students used in the classroom and the reason why they employed them with a focus on 'rebuttal', which is one of the six elements of the argument scheme such as claim, data, warrent, backing, qualifiers, and rebuttal. The analysis of argumentation is based on the five argumentation schemes suggested by Verheij(2005). The experimental class was conducted twice a week with four participants who are third grade middle school students. In the argumentation class students were promoted to address two different kinds of geometrical tasks. After the second session of class, the researcher conducted the semi-structured interview. Accordingly, this study contributes to the existing research by making students to have concrete and active argumentation while obtaining the sound understanding of the argumentation.

• Journal of Korea Spatial Information System Society
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• v.10 no.1
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• pp.15-28
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• 2008

In ubiquitous sensor networks(USN) environment, it is essential to process region query for user-demand services. Using R-tree is a preferred technique to process region query for in-network query environment. In USN environment, USN middleware must select sensors that transfers region query with accuracy because the lifetime of sensors is that of whole sensor networks. When R-tree is used, however, it blindly passes the region query including non-existent sensors where MBR(Minimum Boundary Rectangle) of R-tree is Intersected by region of query. To solve in this problem, we propose a reconstruction of region query method which is a trie-structured Quad tree in the base station that includes sensors in region of query select with accuracy. We observed that the proposed method delays response time than R-tree, but is useful for reducing communication cost and energy consumption.

• Journal of Digital Convergence
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• v.14 no.4
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• pp.407-418
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• 2016

The purpose of this study was to investigate the effect of career preparation program on self-esteem, self-efficacy related career decision-making and career development readiness in university students. The structured career development program was given in 124 participants, Sep.~Dec, 2014 in D city. SPSS/Win 18.0. was used. The 1.06 points were decreased in self-esteem(t=3.39, p=.00) than before. The 14.22 points, 17.36 points were increased in self-efficacy(t=-12.41, p=.00), and career development readiness(t=-13.85, p=.00) than before. It showed the program was effective. Three variables showed correlation with one another. We suggested this structured career preparation program would be applied and extended more in career development for the college students. And the follow-up studies about self esteem and relating factors will be needed.

• Journal of The Korean Association For Science Education
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• v.25 no.2
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• pp.146-161
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• 2005

This case study searched two secondary school science teachers' faiths on experiments in science classes. For this study, scaled questionnaires, open-ended questionnaires, structured and semi-structured interviews were conducted. Classroom activities were observed, and instructional plans and materials were collected. In addition, students of the two teachers' classes were interviewed with respect to their thoughts on the lessons. Data sources were analyzed inductively. The triangulation and the member checking guaranteed the validity of this study. As the results, the teachers' faiths on experiments were related to the constructivism, but the faiths were not in accord with their classroom practices. From these results, it was concluded that the teachers' misjudgments about the students' inquiry levels and unfit reorganizations of the experimental activities were the causes of the gap between the teachers' faiths on experiments and classroom practices.