• Computers and Concrete
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• 제3권6호
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• pp.423-437
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• 2006

Stress wave propagation through concrete is simulated by finite element analysis. The concrete medium is modeled as a homogeneous material with smeared properties to investigate and establish the suitable finite element analysis method (explicit versus implicit) and analysis parameters (element size, and solution time increment) also suitable for rigorous investigation. In the next step, finite element analysis model of the medium is developed using a digital image processing technique, which distinguishes the mortar and aggregate phases of concrete. The mortar and aggregate phase topologies are, then, directly mapped to the finite element mesh to form a heterogeneous concrete model. The heterogeneous concrete model is then used to simulate wave propagation. The veracity of the model is demonstrated by evaluating the intrinsic parameters of nondestructive ultrasonic pulse velocity testing of concrete. Quantitative relationships between aggregate size and testing frequency for nondestructive testing are presented.

• 한국태양에너지학회:학술대회논문집
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• 한국태양에너지학회 2011년도 추계학술발표대회 논문집
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• pp.278-281
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• 2011

This system can predict the maximum output about all illumination levels so that the PV system designer can design the system having the best efficiency. For the output prediction exact about the solar cell, that is the device the basis most in the PV system, the basis has to be in order to try this way. The solution based on Lambert W-function are presented to express the transcendental current-voltage characteristic containing parasitic power consuming parameters like series and shunt resistances. A simple and efficient method for the extraction of a single current-voltage (I-V) curve under the constant illumination level is proposed. With the help of the Lambert W function, the explicit analytic expression for I is obtained. And the explicit analytic expression for V is obtained. This analytic expression is directly used to fit the experimental data and extract the device parameters. The I-V curve of the solar cell was expressed through the modeling using Lambert W-function and the numerical formula where there is the difficulty could be logarithmically expressed This method expresses with the I-V curve through the modeling using Lambert W-function which adds other loss ingredients to the equation2 as to the research afterward. And the solar cell goes as small and this I-V curve can predict the power penalty in the system unit.

• 한국콘텐츠학회논문지
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• 제20권8호
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• pp.101-113
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• 2020

본 연구는 명시적 형태 중심 교수법(FFI)이 영어 약모음 /ə/을 교실 상황에서 EFL 학생에게 교수하는 데 있어 얼마나 효과적인지 조사하였다. 25명의 고등학교 여학생이 13명은 실험집단에 12명은 통제집단으로 나뉘어 참여하였다. 또한, 미국인 여성 한 명도 비교 기준점을 위한 음성자료를 제공하였다. 실험집단 참여자는 한 달 반 동안 연구자의 발음과 텍스트를 음성으로 변환해주는 인터넷 프로그램의 발음을 따라 하고, 개인별로 피드백을 받았다. 처치 전, 후 참여자들은 14개의 2음절 이상 다음절 실험단어와 그 단어가 포함된 문장을 읽었으며 읽은 문장은 음성자료로 녹음되었다. 자료 분석을 위해 대응 표본 t 검증과 비모수 Wilcoxon signed-rank 검증이 사용되었다. 연구 결과에 따르면 실험군 참여자들은 사전 실험보다 사후 실험에서 영어 약모음을 약 40% 짧게 조음하였다. 하지만 모음 조음 공간에서 혀의 위치를 나타내는 F1/F2 formant에서 실험 참여자의 F1/F2 formant 분포형태는 이 연구의 기준점인 539 Hz (F1) × 1797 Hz (F2)와 상이했다. 이 연구의 결과는 반복적인 따라 하기와 적절한 피드백을 제공하는 명시적인 형태 중심 교수법(FFI)이 영어 발음 교수에 일부 효과가 있다는 것을 보여 주었다.

• Journal of Information Technology Applications and Management
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• 제11권4호
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• pp.1-23
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• 2004

This study identifies communication patterns of groups using synchronous text communication medium for their group decision-making, and examines how these patterns are associated with creative solutions to problems. Our research suggests that certain communication behavior of groups, when appropriately organized, can be of help in enhancing creative production of outcomes. A qualitative study was conducted on communication patterns based on an analysis of text-based electronic conversation protocols. Specifically this research tried to overcome existing studies on electronic groups by focusing on interactive process of communication among participants. The major study conclusion; are: (1) The production of creative outcome may depend on the process or sequence of discussion among group members with synchronous text communication medium. That is, proper interactive responses and appropriate control of the discussion process are essential to obtain a high level of performance. (2) It is importantto make discuss rules based on meta-cognitive and interactive protocols in the early stage. Explicit rules relating to internal group processes as well as communication medium use are even more important to groups with electronic communication medium than face-to-face groups.

• 대한수학회지
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• 제50권2호
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• pp.425-444
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• 2013

We construct some hyperbolic hyperelliptic space forms whose fundamental groups are generated by only two or three isometries. Each occurring group is obtained from a supergroup, which is an extended Coxeter group generated by plane re ections and half-turns. Then we describe covering properties and determine the isometry groups of the constructed manifolds. Furthermore, we give an explicit construction of space form of the second smallest volume nonorientable hyperbolic 3-manifold with one cusp.

• 영어어문교육
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• 제16권3호
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• pp.1-18
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• 2010

This study examined the effects of previewing and providing background knowledge on low level EFL readers' comprehension of expository texts and their responses to these treatments. 130 college freshmen were randomly placed into one of three treatment groups and read two expository texts reflecting unfamiliar cultural information. Prior to reading, one group was given previewing instruction, which included vocabulary preteaching and summaries, and a second group was provided with culture-specific background knowledge through watching videos and slides. The third group read each text without any prereading instruction. Immediately after reading a passage, subjects answered a 10-item multiple-choice test. Results showed significant positive effects of the previewing treatment and weak positive effects of the providing background knowledge treatment. Students' responses on the questionnaires revealed that the majority felt that the experimental treatments contributed to comprehension enhancement, made reading more enjoyable, and expedited their reading process. Students in the control group, however, indicated that they needed explicit prereading instruction in order to understand the texts. Pedagogical implications of the findings for EFL reading instruction are provided.

• 한국정보시스템학회:학술대회논문집
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• 한국정보시스템학회 2004년도 추계학술대회
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• pp.499-513
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• 2004

This study identifies communication patterns of groups using Internet Messenger for their group decision-making, and examines how these patterns are associated with creative solutions to problems. Our research suggests that certain communication behavior of groups, when appropriately organized, can be of help in enhancing creative production of outcomes. A qualitative study was conducted on communication patterns based on an analysis of text-based electronic conversation protocols. Specifically this research tried to overcome existing studies on electronic groups by focusing on interactive process of communication among participants. The major study conclusions are: (1) The production of creative outcome may depend on the process or sequence of discussion among group members with Internet Messenger. That is, proper interactive responses and appropriate control of the discussion process are essential to obtain a high level of performance. (2) It is important to make discuss rules based on meta-cognitive and interactive protocols in the early stage. Explicit rules relating to internal group processes as well as communication medium use are even more important to groups with Internet Messenger than face-to-face groups.

• 대한수학회논문집
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• 제32권2호
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• pp.233-260
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• 2017

Let R be a factorial domain. In this work we investigate the connections between the arithmetic of Int(R) (i.e., the ring of integer-valued polynomials over R) and its monadic submonoids (i.e., monoids of the form {$g{\in}Int(R){\mid}g{\mid}_{Int(R)}f^k$ for some $k{\in}{\mathbb{N}}_0$} for some nonzero $f{\in}Int(R)$). Since every monadic submonoid of Int(R) is a Krull monoid it is possible to describe the arithmetic of these monoids in terms of their divisor-class group. We give an explicit description of these divisor-class groups in several situations and provide a few techniques that can be used to determine them. As an application we show that there are strong connections between Int(R) and its monadic submonoids. If $R={\mathbb{Z}}$ or more generally if R has sufficiently many "nice" atoms, then we prove that the infinitude of the elasticity and the tame degree of Int(R) can be explained by using the structure of monadic submonoids of Int(R).

• 대한수학회보
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• 제50권2호
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• pp.407-416
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• 2013

Let E be an elliptic curve over $\mathbb{Q}$ and $p$ be a prime of good supersingular reduction for E. Although the Iwasawa theory of E over the cyclotomic ${\mathbb{Z}}_p$-extension of $\mathbb{Q}$ is well known to be fundamentally different from the case of good ordinary reduction at p, we are able to combine the method of our earlier paper with the theory of Kobayashi [5] and Pollack [8], to give an explicit upper bound for the number of copies of ${\mathbb{Q}}_p/{\mathbb{Z}}_p$ occurring in the $p$-primary part of the Tate-Shafarevich group of E over $\mathbb{Q}$.

• 대한수학회보
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• 제52권3호
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• pp.955-962
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• 2015

It has been established that the role played by complete graphs in graph theory is similar to the role Dowling group geometries and Projective geometries play in matroid theory. In this paper, we introduce a notion of H-tree, a class of representable matroids which play a similar role to trees in graph theory. Then we give some properties of H-trees such that when q = 0, then the results reduce to the known properties of trees in graph theory. Finally we give explicit expressions of the characteristic polynomials of H-trees, H-cycles, H-fans and H-wheels.