• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.201-204
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• 2008

The proposed method, capable of predicting various stress-strain responses in axially loaded concrete confined with FRP (Fiber Reinforced Polymers) composites in a rational manner, is based on the fact that the volumetric expansion due to progressive microcracking in mechanically loaded concrete is an important measure of the extent of damage in the material microstructure. The elastic modulus expressed as a function of area strain and concrete porosity, the energy-balance equation relating the dilating concrete to the confining device interactively, the varying confining pressure, and an incremental calculation algorithm are included in the solution procedure. This procedure enables the evaluation of lateral strains consecutively according to the related mechanical model and the energy-balance equation, rather than using an empirically derived equation for Poisson's ratio or dilation rate as in other analytical methods.

• 한국지형공간정보학회:학술대회논문집
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• 2002.03a
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• pp.17-22
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• 2002

인공위성을 이용한 위치결정시스템인 GPS(Global Positioning System)는 mm 단위의 정밀도로 정적, 동적 위치관측이 가능한 시스템으로 현재 여러 분야에서 활용이 증가하고 있다. 특히 교량, 댐 등 안전이 요구되는 사회기반 시설물의 동적 거동을 기록하고 감시하는데 있어서 GPS가 새로운 관측시스템으로 주목받고 있으며 이를 실용화하기 위한 연구가 활발히 진행되고 있다. 본 연구에서는 GPS를 이용하여 건물의 거동상태를 점검 하는 것을 목적으로 하고 있다. 계절풍에 의한 초고층건물의 거동을 해석하기 위하여 건물 옥상에 GPS, 가속도계, 풍향계, 풍속계를 설치하였다. GPS와 가속도계로를 이용하여 건물의 변위 및 가속도를 5Hz로 관측하였다. GPS를 이용한 변위관측은 1시간, 1분, 1초 등의 간격으로 3차원 변위를 계산하였으며, 계산된 3차원 변위를 가속도계, 풍속계, 풍향계와 연계하여 해석하였다. 대상 건물에 대한 최대 변위를 관측한 결과 계절에 따라 큰 차이를 보였으며 건물의 안정성을 평가할 수 있는 척도인 건물의 고유 진동수의 경우 약 0.2Hz의 값을 얻을 수 있었다. 향후 모든 센서들을 통합하여 실시간으로 건물을 모니터링할 수 있는 시스템을 개발할 경우 건물의 안정성 해석 및 유지보수에 본 연구가 큰 기여를 할 수 있을 것으로 사료된다.

• The Journal of the Korea institute of electronic communication sciences
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• v.17 no.4
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• pp.703-708
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• 2022

K-means clustering is a representative clustering technique. However, there is a limitation in not being able to integrate the performance evaluation scale and the method of determining the minimum number of clusters. In this paper, a method for numerically determining the minimum number of clusters is introduced. The explained variance is presented as an integrated measure. We propose that the k-means clustering method should be performed in the subspace of the PCA in order to simultaneously satisfy the minimum number of clusters and the threshold of the explained variance. It aims to present an explanation in principle why principal component analysis and k-means clustering are sequentially performed in pattern recognition and machine learning.

• Korean Journal of Social Welfare Studies
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• v.42 no.3
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• pp.381-407
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• 2011

This study set out to construct an social capital scale that could be commonly used by social welfare organizations and to apply it to examine any differences in social capital among social welfare organizations. For those purposes, the study distributed a questionnaire by mail to social welfare organizations in 15 cities and provinces across the nation and conducted latent means analysis. The major research findings were as follows. First, as a result of exploratory factor analysis and confirmatory factor analysis, the validity and reliability in measurement indicators of social capital were proved to be satisfactory level. Secondly, social capital were found to be interpreted at the organizational level through the review of levels of analysis. Meanwhile, the configural, metric, and scalar invariance of social capital scale were confirmed, which indicates that the social capital scale can be commonly applied to social welfare organizations. Finally, latent means analysis was carried out to examine differences among social welfare organizations in the subindexes of social capital including network connectivity, setting and sharing of vision, reciprocal norm, trust and cooperation, and group participation. As a result, there were significant differences among social welfare organizations in network connectivity, reciprocal norm, trust and cooperation and group participation but no statistically significant differences among them in sharing of vision, goal and core value. Those findings led to implications needed to manage of social welfare organizations.

• Korean Journal of Cognitive Science
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• v.25 no.4
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• pp.417-433
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• 2014

This research examined whether Korean-learners of French were sensitive to discourse structure in anaphoric pronoun resolution. In the experiments, participants read three-sentenced stories and made judgements about how the last sentence of each story makes sense in relation to previous two sentences on a 7-point Likert scale. The stories differed in whether the subject of the last sentence continued the subject of the preceding sentence, and whether the subject of the last sentence was mentioned with a pronoun or a proper noun. The results from French participants replicated the patterns shown in previous studies. In contrast, Koreans exhibited greater difficulty in interpreting pronoun-subject sentences than noun-subject sentences regardless of subject continuity. These findings are discussed within the context of developmental perspective, which suggests the processing of co-referential interpretation may interact with language proficiency.

• Journal of Educational Research in Mathematics
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• v.14 no.1
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• pp.39-69
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• 2004

This paper investigates the teaching and learning of Linear function relating functional contexts and suggests the improved methods of representation-shift through this analysis. The methods emphasize the link between students' preacquired knowledge of mathematical representations and the way of using those. This methods are explanatory teaching, teaching and teaming based on modelling perspectives or tasks (interpretation, prediction, translation and scaling). We categorize the 8th grade middle school students' errors on the linear function relating real contexts and make a comparative study of the error-remedial effects and the teaching and teaming methods. We present the results of a study in which representation-shift methods based on modelling perspectives and tasks are more effective in terms of flexible connection of representations and error remediation. Also, We describe how students used modelling perspective-taking to explain and justify their conceptual models, to assess the quality of their models and to make connection to other mathematical representation during the problem solving focusing on the students' self-diagnosis.

• The Korean Journal of Elementary Counseling
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• v.11 no.3
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• pp.391-405
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• 2012

The purpose of this study is to discover unique personality traits which the children of 5 social status types using 10 clinical scales of Korea Children's personality test (KCPI-S) in order to define the characteristics of 5 social status types developed as the Korean type. For this purpose, two hypotheses were set and tested. The subjects of this study were 502 children who were 4, 5th and 6th grade elementary school boys and girls in A city. 5 social status types and gender of children were set as the independent variables each, and 10 clinical scales of Korea Children's personality test as the dependent variables. The research hypotheses were analyzed in turn by the multivariate analysis (MANOVA) and t-test. The results are as follows: First, the results of analyzing differences in 10 clinical scales in accordance with 5 social status types how the significant differences in all 9 clinical scales except for language development scale, and ${\eta}^2$ representing the explanatory power of the independent variables to dependent variables was found to be in the range of the lowest at 2% up to 10% for each scale. Second, the results of analysis of the gender difference show that in the case of the children with controversial and neglected children, the significant difference was appeared between boys and girls in 8-9 scales among the 10 clinical scales, but in the case of rest 3 social status types (average, popular, rejected children) the difference was appeared between boys and girls only in 2-3 scales. Depending on these results it seems that each of 5 social status types of the children has its own unique personality structure. It is necessary to attend to the fact that in the case of the children with controversial and neglected children, the average value of boys are significantly higher than that of the girls. There is a big possibility that the boys have more psychological problems that the girls. It is judged that in case of these two types the personal traits applying gender should be interpreted. Therefore, the follow-up study should conduct the exploratory research on the structure of the relationship between children's language development and sociality measure. Further, it is necessary to conduct the psychological comparison between genders in the children with controversial and neglected children, and to study the structure of their relationship with rest social status types by genders.

• Economic and Environmental Geology
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• v.41 no.6
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• pp.763-771
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• 2008

Uncertainties are pervasive in engineering geological problems. Therefore, the presence of uncertainties and their significance in analysis and design of slopes have been recognized. Since the uncertainties cannot be taken into account by the conventional deterministic approaches in slope stability analysis, the probabilistic analysis has been considered as the primary tool for representing uncertainties in mathematical models. However, some uncertainties are caused by incomplete information due to lack of information, and those uncertainties cannot be handled appropriately by the probabilistic approach. For those uncertainties, the theory of fuzzy sets is more appropriate. Therefore, in this study, fuzzy reliability analysis has been proposed in order to deal with the uncertainties which cannot be quantified in the probabilistic analysis due to the limited information. For the practical example, a slope is selected in this study and both the probabilistic analysis and the fuzzy reliability analysis have been carried out for planar failure. In the fuzzy reliability analysis, the dip angle and internal friction angle of discontinuity are considered as triangular fuzzy numbers since the random properties of the variables cannot be obtained completely under the conditions of limited information. In the study, the fuzzy reliability index and the probabilities of failure are evaluated from fuzzy arithmetic and compared to those from the probabilistic approach using Monte Carlo simulation and point estimate method. The analysis results show that the fuzzy reliability analysis is more appropriate for the condition that the uncertainties arise due to incomplete information.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.36S no.7
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• pp.134-135
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• 1999

This paper presents a speech enhancement method with spectral subtraction using wavelet, wavelet packet and cosine packet transforms which are known as multiresolutional signal analysis method. The performance of each method is compared with the conventional spectral subtraction method. Performance assessments based on average SNR, cepstral distance and informal subjective listening test are carried out. Experimental result demonstrate that cosine packet shows the best result in objective performance measure as well as subjective shows less musical noise than the conventional spectral subtraction method after removing the noise components.

• Journal of the Korean Society of Propulsion Engineers
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• v.25 no.1
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• pp.42-49
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• 2021

As a measure of susceptibility on the combustion instability, thermo-acoustic instabilities in rocket combustion system was considered for the estimation of the operational stability margin. Growth rate, which governs the asymptotic stability behavior of the system, was determined from the dynamic data measured during combustion tests in order to understand the dynamic characteristics of combustor system. Frequency transform technique was first applied to determine the system parameters such as growth rate and/or damping coefficient for an interested mode from the time series pressure data, and the PDFs of pressure amplitude were extracted from the amplitude envelope of pressure oscillation for the stochastic analysis.