• Environmental Analysis Health and Toxicology
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• 제19권2호
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• pp.191-200
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• 2004

Zinc (Zn) is an essential element in biological process, however inadequate Zn status in general population have been recognized. To update the knowledge for Zn-cadmium (Cd) interaction, we studied the intestinal uptake and transport, and the expression of metal transporter proteins (divalent metal transporter 1, DMT1 ; metal transporter protein 1, MTP1 ; zinc transporter 1, ZnTl ; metallothionein 1 , MT1) in duodenum after Cd exposure using Zn deficient animal model. Rats were led Zn deficient (ZnD, 0.5-1.0 mgZn/kg) or Zn supplemented (ZnS, 50mg Zn/kg) diet for 4 weeks, and followed single administration of $^{109}$ CdCl$_2$orally. The body Zn flatus and tissue Cd concentration were determined at 24 hrs after Cd administration. Total body burden of Cd and Cd absorption index (AI, %) were estimated based on the tissue Cd analyzed. DMT1, MTP1, ZnTl and MT1 mRNA were analyzed by using RT-PCR method. Feeding of Zn deficient diet for 4 weeks produced a reduced body weight gain and a depletion of body Zn. Tissue Cd concentration, body burden of Cd and Cd absorption index were higher in the ZnD diet fed rats than the ZnS diet red rats. Especially, Cd concentration in the small intestine (duodenum, jejunum and ileum) and the colon of FeD diet fed rats were higher markedly than in the FeS diet group. The expression levels of DMT1, MTP1 and ZnT1 mRNA in FeD diet fed rats were similar to the FeS diet. The level of MT1 mRNA expression was significantly lower in the FeD than the FeS diet fed rats. Taken together, theses results indicate that Zn deficiency in diet induce an increased intestinal absorption and tissue retention of Cd, and down -regulate the MT1 expression in the intestine which might be play a part of role in Cd absorption and transport in mammalian. These findings suggest that deficiency of essential metal could be enhanced the toxicity of toxic, non-esstial metals through the metal-metal interaction.

• 한국수학교육학회지시리즈E:수학교육논문집
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• 제38권1호
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• pp.69-92
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• 2024

본 연구는 수열에 대한 학생의 두 가지 인식을 바탕으로 고등학교 수열 수업에서 나타나는 학생의 수학 주목하기를 분석하였다. 구체적으로 수학 주목하기를 초점의 중심, 초점을 유발하는 상호작용, 수학 과제의 특징, 수학 활동의 본질의 네 가지 측면에서 분석하여 다음의 결과를 얻었다. 우선 초점의 중심 변화 양상은 '초점을 유발하는 상호작용', '물질적 자원', '수학 활동의 본질' 중 어떤 한 구성요소만으로는 유일하게 묘사될 수 없었다. 다음으로 수학 주목하기 구성요소 간의 상호작용이 식별되었으며, 소집단 활동에서의 교사의 개별 피드백은 초점의 중심 형성에 영향을 주었다. 마지막으로 학생들은 동일 교실, 즉 동일 초점을 유발하는 상호작용, 물질적 자원, 수학 활동의 본질 내에서도 서로 다른 두 가지 추론 양상을 보였다. 본 연구가 마중물이 되어 수열에 대한 학생의 이해 연구가 더욱 활발히 진행되길 기대한다.

• 한국초등과학교육학회지:초등과학교육
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• 제24권5호특별호
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• pp.595-601
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• 2005

In this study, the scientifically gifted students and the general students were compared in terms of the following components in cooperative teaming: whom they interacted with, to/from whom they gave/received help and why, and what kinds of the verbal interaction patterns they engaged in. The subjects were 4th graders. The data were collected through the investigation of the students' perception and videotaping of the small group interactions of each group. The results showed that the gifted students interacted with most students in their groups. They complemented each others' opinions and their discussion was enriched through their interactions. On the other hand, the interactions of the general students occurred mostly around a leader, and more teamed students explained the content to the less teamed students. Predominantly, the gifted students' most verbal behaviors were related with the teaming contents. Most frequent verbal behavior were a giving specific information and an explanation of their opinions. The general students, however, gave simple and short information, and more often they showed the management behaviors, such as encouraging participation and suggesting their directions.

• 한국과학교육학회지
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• 제37권1호
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• pp.63-75
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• 2017

본 연구는 반응적 교수법이 학생들의 생산적인 과학적 논변 실행에 미치는 영향을 탐색하였다. 중학교 2학년 학생 30명과 교사 1명이 본 연구에 참여하였고 자극과 반응 단원의 논변 수업을 진행하였다. 학생들은 측정 활동의 결과를 예상하고, 활동을 통해 결과를 얻고, 그 결과를 설명하기 위한 논변 활동을 진행하였다. 이 활동은 정수리, 척추, 손등 위에서 핸드폰 진동 감지 시간을 측정하는 것이었다. 연구자들은 수업에 대한 교사의 생각을 알고자 교사 인터뷰를 진행하였고, 각 소집단 활동과 교사 인터뷰를 녹음 녹화하였다. 녹음 기록을 전사하여 분석 자료로 활용하였으며, 소집단 논변 활동에서 학생들의 인식론적 프레이밍과 교사의 반응적 교수 실행을 분석하였다. 연구 결과, 교사는 반응적 지원의 시작점이 될 학생 사고를 이끌어내는 질문과 함께 소집단 실행에 개입하였다. 교사는 논변 수업에 대한 인식과 학생의 사고를 이해하고자 하는 태도에서 생산적 프레이밍을 드러냈으며, 이를 토대로 수업에서 학생들의 사고를 이끌어내며 논의의 활성화를 지원하였다. 그리고 교사는 평가자의 관점을 지양하고 학생의 아이디어에 반응하여 반박 발화를 함으로써 논변 활동의 일원으로 참여하였다. 교사는 이러한 참여를 통해 소집단 내의 인지적 권위 구조를 변화시켰으며, 학생들에게 논변 활동에서 기대하는 실행의 예시를 보여주어 생산적 프레이밍을 지원하였다. 이러한 교사의 반응적 교수 실행 결과 학생들은 생산적인 과학적 실행을 보였고, 이는 학생들의 변화된 인식론적 프레이밍에서 비롯된 것으로 보인다. 본 연구는 학생이 과학적 논변 활동에서 진정한 과학적 실행에 참여하도록 생산적 프레이밍을 지원하는 교사의 반응적 교수 전략을 구축하는 데에 기여할 것으로 기대된다.

• Interaction and multiscale mechanics
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• 제2권1호
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• pp.45-68
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• 2009

An aim of the study is to develop an efficient numerical simulation technique that can handle the two-scale analysis of fluid permeation filters fabricated by the partial sintering technique of small spherical ceramics. A solid-fluid mixture homogenization method is introduced to predict the mechanical characters such as rigidity and permeability of the porous ceramic filters from the micro-scale geometry and configuration of partially-sintered particles. An extended finite element (X-FE) discretization technique based on the enriched interpolations of respective characteristic functions at fluid-solid interfaces is proposed for the non-interface-fitted mesh solution of the micro-scale analysis that needs non-slip condition at the interface between solid and fluid phases of the unit cell. The homogenization and localization performances of the proposed method are shown in a typical two-dimensional benchmark problem whose model has a hole in center. Three-dimensional applications to the body-centered cubic (BCC) and face-centered cubic (FCC) unit cell models are also shown in the paper. The 3D application is prepared toward the computer-aided optimal design of ceramic filters. The accuracy and stability of the X-FEM based method are comparable to those of the standard interface-fitted FEM, and are superior to those of the voxel type FEM that is often used in such complex micro geometry cases.

• 대한치과보철학회지
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• 제32권3호
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• pp.445-454
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• 1994

Osseointegrated implant prostheses are to provide normal function without compromising the unique interaction between the tissue and the implant. The essential requirement for the osseointegrated implant prostheses is passive fit of abutment. Therefore, the impression must be accurate and reproduciable since the resultant master cast precisely duplicates the clinical condition. The purpose of this study was to compare the accuracy of the master casts obtained from five impression techniques. Group 1 : To take impression with indirect technique and Impregum F. Group 2 : To take impression with unsplinted direct technique and Impregum F. Group 3 : To take impression with splinted direct technique and Impregum F. Group 4 : To take impression with unsplinted direct technique and Xanthano. Group 5 : To take impression with splinted dierct technique and Xanthano. The results were as follow : 1. In taking impression of Impregum F, there was no significant difference between to use of indirect technique and unsplinted direct technique.(p<0.05) 2. Unsplinted direct technique with Impregum F is less accurate than splinted direct technique with Impregum F or Xanthano and unsplinted direct technique with Xanthano.(p<0.05). 3. There was no significant difference between splinted direct technique with Impregum F and unsplinted direct technique with Xanthano.(p<0.05) 4. Splinted direct technique reproduce more accurate than unsplinted direct technique.(p<0.05) 5. Impression plaster produced less distortion than polyether.(p<0.05) As a result, splinted direct technique with Xanthano was the most accurate technique. As a result, splinted direct technique with Xanthano was the most accurate technique in this study. In addition to dimensinal changes in the materials used, positional errors were also attributed to the mechanical components used in the transfer porocess. Although the errors measured were relatively small, this study demonstrates the potential for distortions with the transfer technique used. Further study is indicated that ?the technique will be able to reproduce the intraoral relationship of implant fixtures reliably and predictably.

• 대한수학교육학회지:수학교육학연구
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• 제9권1호
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• pp.263-278
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• 1999

Computer with various powerful functions has profound potential for mathematics instruction and learning. As computer technology progress, its applicability to mathematics education become more comprehensive. Not only its functional development but various psychological positions also changed the way computer technology utilized in mathematics education. In behaviorist's perspective, computer viewed as a teaching machine and constructivist viewed computer as microworld where students could explore various mathematical contents. Both theoretical positions emphasized individual aspect of learning because behaviorist tried to individualize learning using computer and constructivist focused on the process of individual construction. But learning is not only a individual event but also a social event. Therefore we must take social aspect into account. This is especially important when it comes to computer based learning. So far, mathematics loaming with computer weighed individual aspect of loaming. Even in microworld environment, learning should be mediated by teacher and collaborative learning activities. In this aspect, the roles of teacher and peers are very important and socio-cultural perspective sheds light on the computer based learning. In socio-cultural perspective, the idea of scaffold is very important in learning and students gradually internalize the social dimension and scaffolding is gradually faded. And in the zone of proximal development, teacher and more competent peers guide students to formulate their own understanding. In sum, we must take following points into account. First of all, computer should not be viewed as a medium for individualized teaming. That is, interaction with computer should be catalyst for collaborative activities with peers. So, exploration in computer environment has to be followed by small group activities including small group discussion. Secondly, regardless of the role that computer would play, teacher should play a crucial role in computer based learning. This does not mean teacher should direct every steps in learning process. Teacher's intervention should help student construct actively. Thirdly, it is needed to conceptualize computer in learning situation as medium. This would affect learning situation and result in the change of pre-service and in-service teacher training. Computer to be used effectively in mathematics classroom, researches on assessment of computer based learning are needed.

• 대한수학교육학회지:학교수학
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• 제12권2호
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• pp.177-191
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• 2010

많은 교육학자들은 학교 수업에서 소집단 협력학습을 강조하고 있다. 소집단 협력 학습은 구성원 간의 의사소통을 통해 학습 능력의 향상 뿐 아니라 정의적 태도 면에서도 도움을 준다. 학습 능력의 향상이라는 측면에서 보면 상대적으로 부진한 학생들은 개념, 원리, 법칙들을 이해하면서 문제해결 능력이 향상됨을 스스로 느끼는데 반해 상대적으로 우수한 학생들은 그 효과에 대해 반신반의하고 있다. 따라서 본 연구는 수학 학습 능력이 상대적으로 우수한 학생이 부진한 학생과의 상호작용 특히 부진한 학생에게 수학을 지도하면서 어떤 수학 학습 과정을 가지는지를 탐색하고자 하였다. 본 연구 결과 상대적으로 우수한 학생은 동료를 지도함으로 인해 문제해결능력과 의사소통 능력이 향상되는 모습을 보였으며, 높은 수준의 수학적 사고를 하는 모습을 보였다.

• 대한지구과학교육학회지
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• 제3권1호
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• pp.65-75
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• 2010

The purpose of this study is to present a Freedom Inquiry Method by Revised Science Curriculum in 2007. This study introduced IIM(Independent Inquiry Method), PBL(Problem Based Learning), Small Inquiry Method, Science Notebooks, Project Learning Method about Freedom Inquiry Method. The results of this study are as follows: First, IIM(Independent Inquiry Method) is studying method in the inquiry process center. The inquiry process is composed of total 9 phases, inquiry subject really it is, detailed aim deciding, information searching, it searches, quest result it arranges, aim evaluation, the report making, it announces, it evaluates, it is become accomplished. Second, It is a studying method which it starts with the problem which is Problem Based Learning, study atmosphere creation phase, problematic presentation phase and sleep static problem solving the phase which it attempts, it is become accomplished with autonomous studying phase, coordinated studying and discussion studying phase, discussion resultant announcement studying phase, arrangement and evaluation. Third, Small Inquiry Method, Call it accomplishes the call grade of the students among ourselves 4~8 people degree where only the quest learning capability is similar within class. Also interaction and coordinated function of the members between it leads and the subject which is given in the group it cooperates and it solves with it is a quest method which arrives to aim of commonness. This method divides on a large scale in three parts, it becomes accomplished in programming phase, quest accomplishment and resultant announcement. Fourth, Science Notebooks learns a scientific contents and a scientific quest function and the possibility of decreasing in order to be, from the fact that the help which it understands. This planing, data searching, it searches, becomes accomplished with resultant arrangement, announcement and evaluation. Fifth, The Project Learning Method the studying person oneself studying contents, it establishes a plan and it collects it accomplishes process of etc. it evaluates it leads and a subject and information and with real life it is a method which it studies naturally from the learning environment inside which is similar. This is preliminary phase, project start, project activity and project arrangement.

• Asian-Australasian Journal of Animal Sciences
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• 제18권12호
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• pp.1761-1768
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• 2005

Effects of alpha-galactosidase (GAL) on broiler corn-soybean meal diet was investigated. In experiment 1, sixty cockerels were allocated to five groups, including three enzyme treatments (GAL added at 0, 500, and 1,000 mg/kg diet), a nitrogen-free diet group and a fast group. The true nitrogen-corrected ME (TME$_n$) and true amino acid availability were determined. In experiment 2, 324 day-old chicks were used in a 2${\times}$3 factorial design consisting of two energy contents (high and low) and three GAL levels (0, 250, and 500 mg/kg). Three feeding phases, comprising 0-21 d, 22-35 d and 36-48 d, were involved. GAL addition improved TME$_n$ and the availability of methionine and cystine (p<0.05). The apparent ME (AME) or nitrogen-corrected AME (AME$_n$) and digestibility of dry matter, organic matter, calcium, and phosphorus were improved significantly on d 21, so was crude protein and an interaction of energy and GAL on AME$_n$ (p<0.05) was found on d 35. However, daily intake and daily gain were significantly improved with GAL addition (p<0.05) during 21 d. The small intestine relative weight decreased at 250 mg/kg GAL (p<0.05) on d 35, whereas presented an interaction between GAL and energy on d 21 (p<0.05). Likewise, this treatment increased breast muscle ratio (p<0.05). On d 21, triglycerides level of broilers showed interaction between energy and enzyme levels (p<0.05). Uric acid level in 500 mg/kg GAL declined linearly (p<0.05). On d 35, quadratic effects (p<0.05) were observed in total protein, albumin, globulin and cholesterol content for enzyme supplementation. And the interactive effects of energy and GAL on serum values showed more obviously. The study implies that GAL improved energy and nutrient availability of corn-soybean meal diet in broiler. The GAL supplementation to corn-soybean meal based diet can improve performance of broilers in early stages of growth.