• Magazine of the Korea Concrete Institute
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• v.6 no.1
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• pp.89-100
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• 1994

The current test procedure for transfer length, which determine transfer length by measuring concrete strain, has an actual bond stress state in the prestressed pretensioned member : however, it is difficult to determine the bond properties of maximum bond stress and bond stiffness with this method. It is also difficult for design engineer to understand and select a correct safety criterion from the widely distributed results of such a ransfer test alone. An alternative testing procedure is provided here to determine the bond properties without measuring the concrete strain. In this test the bond stress is measured directly by creating a similar boundary condition within the transfer length in a real beam during the transfer of prestressing force. The prestressing force was released step by step by step from the unloading side. The release of force induces a swelling of the strand at the unloading side of concrete block, bonding force in the block, and a bond slip of the strand toward the other side of the block. Two center-hole load cells are used to record the end loads until the point of general bond slip(maximum bond stress). It is suggested that this test procedure be performed with the ordinary transfer test when determining the transfer length in a prestressed, pretensioned concrete beam.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.27 no.9
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• pp.555-560
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• 2014

In this paper, in order to develop outstanding Pb-free composition ceramics, the $Fe_2O_3$-doped ($Na_{0.525}K_{0.443}Li_{0.037}$)($Nb_{0.883}Sb_{0.08}Ta_{0.037}$)$O_3$ + 0.3 wt% $Bi_2O_3$ + x wt% $Fe_2O_3$ (x= 0~1.0 wt%)(abbreviated as NKL-NST) lead-free piezoelectric ceramics have been synthesized using the ordinary solid state reaction method. The effect of $Fe_2O_3$-doping on their microstructure and electrical properties were investigated. XRD diffraction pattern studies confirm that $Fe_2O_3$ completely diffused into the NKL-NST lattice to form a new stable soild solution with $Fe^{3+}$ entering the $Nb^{5+}$, $Sb^{5+}$ and $Ta^{5+}$ of B-site. And, phase structure of all the ceramics exhibited pure perovskite phase and no secondary phase was found in the ceramics. The ceramics doped with 0.6 wt% $Fe_2O_3$ have the optimum values of piezoelectric constant($d_{33}$), planar piezoelectric coupling coefficient($k_p$) and mechanical quality factor($Q_m$) : $d_{33}$ = 233 [pC/N], $k_p$= 0.44, $Q_m$= 95. These results indicate that the ($Na_{0.525}K_{0.443}Li_{0.037}$)($Nb_{0.883}Sb_{0.08}Ta_{0.037}$)$O_3$ +0.3 wt% $Bi_2O_3$ + 0.6 wt% $Fe_2O_3$ ceramic is a promising candidate for lead-free piezoelectric ceramics.

• Tunnel and Underground Space
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• v.9 no.4
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• pp.296-305
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• 1999

In ordinary back analysis it if hardly possible to obtain the mechanical properties of tunnel lining by using commonly measured displacements of tunnel lining, because only a few displacements could be measured at the site. Therefore, it is necessary to develop a new method which can evaluate the state of stresses of tunnel by using measured data. In this study, in order to assess tunnel lining stability by estimating its stresses with a few measured displacements, a formulation of back analysis method was proposed. The accuracy of results were investigated through the parametric study for several types of measurement model of two dimensional elastic lining. This new back analysis method to assess tunnel lining stresses and strains with a few numbers of measured displacements showed high accuracy and good applicability when compared to the results of numerical experiments by FEM. The method has been tested on subway tunnel and its applicability has been confirmed by comparing field and analytical data. It is verified that the stress on the tunnel lining can be obtained by only more than 3 point of input displacements without any condition of external loads.

• Computers and Concrete
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• v.19 no.1
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• pp.59-68
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• 2017

This study focused on modeling the behavior of the compressive stress using the average strain and ultrasonic test results in concrete. Feed-forward backpropagation artificial neural network (ANN) models were used to compare four types of concrete mixtures with varying water cement ratio (WC), ordinary concrete (ORC) and concrete with short steel fiber-reinforcement (FRC). Sixteen (16) $150mm{\times}150mm{\times}150mm$ concrete cubes were used; each contained eighteen (18) data sets. Ultrasonic test with pitch-catch configuration was conducted at each loading state to record linear and nonlinear test response with multiple step loads. Statistical Spearman's rank correlation was used to reduce the input parameters. Different types of concrete produced similar top five input parameters that had high correlation to compressive stress: average strain (${\varepsilon}$), fundamental harmonic amplitude (A1), $2^{nd}$ harmonic amplitude (A2), $3^{rd}$ harmonic amplitude (A3), and peak to peak amplitude (PPA). Twenty-eight ANN models were trained, validated and tested. A model was chosen for each WC with the highest Pearson correlation coefficient (R) in testing, and the soundness of the behavior for the input parameters in relation to the compressive stress. The ANN model showed increasing WC produced delayed response to stress at initial stages, abruptly responding after 40%. This was due to the presence of more voids for high water cement ratio that activated Contact Acoustic Nonlinearity (CAN) at the latter stage of the loading path. FRC showed slow response to stress than ORC, indicating the resistance of short steel fiber that delayed stress increase against the loading path.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.2
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• pp.380-386
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• 2018

One of the most difficult technical aspects of music is vocals (the voice). Unlike ordinary musical instruments, it is difficult to apply common values because the tone (that is, the color) varies greatly depending on the singer, and therefore, it is necessary to properly mix in various effects. Therefore, this study is intended to suggest concepts, the current state, and effective usage of reverberation (or reverb), which is the most typical of vocal effects, using wave renaissance reverb, which is one of the effects that are the most commonly used by students. The most important part of the mixing process in popular music is how to enhance the voice. Since the spatial impression of sound makes music more beautiful, the role of reverb as a vocal effect is absolute. Computer technology has made it easier to create music, but it has produced a side effect in which individual technique falls short, such as using predetermined presets only. Studies on the use of reverb by musicians through more detailed efforts are expected to contribute to creating good music.

• Journal of Korean Library and Information Science Society
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• v.20
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• pp.241-284
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• 1993

Through the restoration, we can find that the register of houses, inhabitants and their ancestry, which is in the Sunsung Kim family registers, was fundamentally the census register of Kim Roe including more ancestry transformed into the lists of house, inhabitants and their ancestry of Kim Roe, Kim Bang-Seek, Kim Sung-Sae and Kim Hee-Bo. And we can find also the original forms were considerably damaged. That is, in the course of transformation, considerable parts of the contents of ancestry were not needed, so they were removed, the recordings of brotherandsisters, sons and their servants were also removed. By comparing of the restored census register of Kim Roe and the Sunsung Kim family registers, we can know the fact that when they published the family registers, the contents of the founder to the ninth descendants were totally depended on the census register of Kim Roe. The Census Register of King Taejo of Choson Dynasty(National Treasure No. 131) which has been recorded almost same periods as the census register of Kim Roe was remained as an original state. Therefore, it was greatly helpful for restoring the census register of Kim Roe. There were few materials which we can know the way of ordinary life in Koryo period. But through the census register of Kim Roe and the census Register of King Taejo of Choson Dynasty, we have a glimpse of their life history. Nevertheless we can find some demerits in the census register of Kim Roe as followers : First, it is not an original but a transformed one, while the Census Register of King Taejo of Choson Dynasty is first materials. Second, it was recorded the only one family. Finally, it was omitted the parts of his brotherandsisters, children and servants who lived with their master. According to these demerits its worth of materials for history will be descended more or less. Therefore, when we use this material, we should treat it more considerably.

• Korean Journal of Human Ecology
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• v.16 no.6
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• pp.1083-1095
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• 2007

This study had been done to investigate that early childhood teacher's recognition and demand on children's language education and 20 early childhood teachers were interviewed individually who work at state-owned/ public-owned/ private-owned kindergardens residing G, I, and K cities in Jeollabuk-do. First, the purpose of language education was recognized on the formations of essence, concept, expertise, technique and attitude toward language. Second, the contents of language education must be selected by children's experience that they encounter in ordinary life based on oral language and written language. Besides, early childhood teachers strongly felt the necessity of new contents of language education, although they thought of insufficiency of their knowledge on the issue. Third, the method of language education was mainly accomplished by teaching material and objects. Besides, they were aware of looking for new organized teaching methods and also concerned of the importances of teacher's attitude and group formation method. Fourth, the evaluation of language education must be acquired by desirable evaluation method that was based on the recognition of children's unrealistic language capabilities, even though they had recognized the difficulty to do because of knowledge insufficiency. They also showed the tendency of negligence on the evaluation of language education. Fifth, the required facts for early childhood teachers on language education were development and supply of teaching materials, demand on teacher's education and appropriate evaluation method, and cognitive changes on language education by public toward the written language.

• Structural Engineering and Mechanics
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• v.66 no.6
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• pp.677-691
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• 2018

Reliability assessment of complex structures using simulation methods is time-consuming. Thus, surrogate models are usually employed to reduce computational cost. AK-MCS is a surrogate-based Active learning method combining Kriging and Monte-Carlo Simulation for structural reliability analysis. This paper proposes three modifications of the AK-MCS method to reduce the number of calls to the performance function. The first modification is related to the definition of an initial Design of Experiments (DoE). In the original AK-MCS method, an initial DoE is created by a random selection of samples among the Monte Carlo population. Therefore, samples in the failure region have fewer chances to be selected, because a small number of samples are usually located in the failure region compared to the safe region. The proposed method in this paper is based on a uniform selection of samples in the predefined domain, so more samples may be selected from the failure region. Another important parameter in the AK-MCS method is the size of the initial DoE. The algorithm may not predict the exact limit state surface with an insufficient number of initial samples. Thus, the second modification of the AK-MCS method is proposed to overcome this problem. The third modification is relevant to the type of regression trend in the AK-MCS method. The original AK-MCS method uses an ordinary Kriging model, so the regression part of Kriging model is an unknown constant value. In this paper, the effect of regression trend in the AK-MCS method is investigated for a benchmark problem, and it is shown that the appropriate choice of regression type could reduce the number of calls to the performance function. A stepwise approach is also presented to select a suitable trend of the Kriging model. The numerical results show the effectiveness of the proposed modifications.

• The Journal of the Korea Contents Association
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• v.14 no.7
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• pp.70-82
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• 2014

The competitive circumstance among domestic TV stations caused by TV channels of comprehensive programming appearance in 2011 brought the rapid growth of talk shows. The purpose of this article is to diagnose the talk shows trend from a self-disclosure perspective to consider a social aspect and communication structure in popular TV programs. 26 domestic TV talk shows from 2011 to 2014 were collected and analyzed to understand current state and grasp genres and formats. The results show that self-disclosure talk shows are increasing under the leading of terrestrial TV channels. The talk only type of talk show is superior in numbers compare to the variety type talk show includes such as game and quiz. The popular talk shows were produced inside studio mainly with fun seeking topics. Multi MCs and guests encountered many to many communication structure. The marked changes among self-disclosure talk shows to encourage participation of entertainers' family members and ordinary people are emerging and it is a noteworthy phenomenon.

• Journal of the Korea Convergence Society
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• v.6 no.6
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• pp.185-193
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• 2015

The wisdom contents consists of an ordinary person's ideas and experience. The Wisdom Market [1] is an online business model where wisdom contents are traded. Thus, the general public could do business activities in the Wisdom Market at ease. As the wisdom contents are themselves the thought of persons, there exists many similar or duplicated contents. Existing copyright protection schemes mainly focus on the primary author's right. Thus, it's not appropriate for protecting the contents of Collective Intelligence that requires to protect the rights of collaborators. There should exist a new method to be dynamic capable of combining and deleting rights of select collaborators. In this study, we propose collective copyright authentication scheme suitable for the contents of Collective Intelligence. The proposed scheme consists of collective copyright registration, addition and verification protocols. It could be applied to various business models that require to combine multiple rights of similar contents or to represent multiple authorships on the same contents.