• Restorative Dentistry and Endodontics
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• 제40권1호
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• pp.1-13
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• 2015

Advancements in bio-ceramic technology has revolutionised endodontic material science by enhancing the treatment outcome for patients. This class of dental materials conciliates excellent biocompatibility with high osseoconductivity that render them ideal for endodontic care. Few recently introduced bio-ceramic materials have shown considerable clinical success over their early generations in terms of good handling characteristics. Calcium enriched mixture (CEM) cement, Endosequence sealer, and root repair materials, Biodentine and BioAggregate are the new classes of bio-ceramic materials. The aim of this literature review is to present investigations regarding properties and applications of CEM cement in endodontics. A review of the existing literature was performed by using electronic and hand searching methods for CEM cement from January 2006 to December 2013. CEM cement has a different chemical composition from that of mineral trioxide aggregate (MTA) but has similar clinical applications. It combines the biocompatibility of MTA with more efficient characteristics, such as significantly shorter setting time, good handling characteristics, no staining of tooth and effective seal against bacterial leakage.

• Educational Technology International
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• 제17권2호
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• pp.273-305
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• 2016

The EBS teaching coaching program, '선생님이 달라졌어요' broadcasted about 30 dramatic teaching improvement cases. The TV program has gained great attention and been used widely as a good example for making some meaningful improvements in teaching. However, there has not been an attempt to research and gather the series beyond the individual coaching examples for the viewers (mainly teachers) to obtain more comprehensive educational insights of the results. This study, therefore, reviews the program and conveys how the overall coaching actually took place, examines changes in classrooms, and discusses the implications the results with theoretical foundations. The researcher selected 12 teachers' coaching cases among 30 ones. Then the reviewers reviewed the program with the 6 categories. According to the results, the coaching took place 6-8 months for each individual teacher. The common difficulty teachers shared was a big gap between teachers' effort for teaching versus 'students problematic behaviors' in class. The overall direction for the coaching solution was 'to improve the relationship with students' first rather than to mainly focus on teaching the content. Students changed and actively participated in the learning process when teachers improved their relationships with the students. The researcher discussed how building good relationships with students greatly affects the improvement in teaching with the 'Needs Hierarchy' and 'Brain Science' theories.

• 대한지구과학교육학회지
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• 제7권1호
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• pp.119-132
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• 2014

In recent years, Korea encourages teachers to do STEAM education(Science, Technology, Engineering, Arts & Mathematics), which includes Arts to STEM education to train creative science technology talent. Related to this, we developed a subject substitute STEAM program for the 6th grade students in elementary school and applied it in a field. The STEAM program which substitutes contents in curriculum related to Energy unit was developed and it was taught to twenty four sixth grade students during regular classes. During the classes, all activities of students were observed and they were written in recording notes during the observation. After all STEAM program ended, how students recognize the subject substitute STEAM program compared to general class, understand learning contents and think about the program before and after the STEAM classes were analyzed through questionnaire and interviews. The results were as follows. First, some students had difficulty in reconciling different ideas in group, creative thinking and crafts but most students liked the STEAM classes because many activities are fun and it is easy to understand. Second, learners regarded practical use of knowledge, learning different subjects together and interests as the reasons they can understand learning contents easily during STEAM program. Third, learners recognized STEAM classes are good to understand knowledge, think creative ideas and improve social skills after the STEAM classes while they showed anticipation, worry and fear before taking the classes. It is found that a subjective substitute STEAM program is helpful to increase learners' interests in learning, understand learning contents, increase creativity and have a good personality through a qualitative research.

• 과학교육연구지
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• 제36권2호
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• pp.313-328
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• 2012

본 연구는 2009 교육과정이 탐구활동을 강조함과 동시에 MBL의 사용에 대해 직접적으로 권장하고 있음을 기반으로 하여 학교 현장에서의 MBL 활용도를 높이기 위한 목적으로 실시되었다. 초중등 교사 및 예비교사를 대상으로 MBL 활용 연수를 실시하고 연수에 대한 만족도 및 MBL에 활용 대한 인식을 조사한 결과 연수에 대한 만족도가 높은 것으로 나타났으며 장비의 활용가능성 및 학생들의 기대되는 변화 및 교사의 적용의지 모두 높았다. 그 중 학생들의 호기심 및 과학에 대한 흥미가 높아질 것이라고 기대한다는 응답이 가장 높았는데, 이것은 MBL이 학생들의 과학에 대한 흥미부족에 대한 문제 해결을 위한 방안으로 사용될 수 있다고 볼 수 있다. 또한 전반적으로 중등이나 예비교사 보다는 초등교사가, 낮은 경력의 교사보다는 높은 경력의 교사가, MBL을 사용해본 경험이 없는 교사보다는 경험이 있는 교사가 연수에 대한 높은 만족도와 적용 의지를 보이는 것으로 나타났다. MBL 고급 연수 개설시 초등교사나 예비교사들은 STEAM 교육에서의 MBL 활용에 대한 연수를 많 이 희망하였고, 중등교사들은 창의성 신장을 위한 MBL 활용 연수를 희망하였다. MBL 수업을 적용하는데 장애 요소로는 가격의 문제를 가장 많이 지적하였으며, 실험 안내서와 교사 교육의 부족이라는 응답이 다음으로 많았다. 결론적으로 현장에 장비가 충분히 갖추어 지고, 활용 방법에 대한 연수가 지속적으로 제공된다면 과학 교육 현장에서 MBL 활용도를 높일 수 있을 것으로 기대된다. 또한 앞으로 MBL 활용 연수 프로그램을 구성할 때 본 연구의 결과가 활용될 수 있을 것이다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제41회 하계 정기 학술대회 초록집
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• pp.148-148
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• 2011

Recently, there have been many research activities to develop the large-area plasma source, which is able to generate the high-density plasma with relatively good uniformity, for the plasma processing in the thin-film solar cell and display panel industries. The large-area CCP sources have been applied to the PECVD process as well as the etching. Especially, the PECVD processes for the depositions of various films such as a-Si:H, ${\mu}c$-Si:H, Si3N4, and SiO2 take a significant portion of processes. In order to achieve higher deposition rate (DR), good uniformity in large-area reactor, and good film quality (low defect density, high film strength, etc.), the application of VHF (>40 MHz) CCP is indispensible. However, the electromagnetic wave effect in the VHF CCP becomes an issue to resolve for the achievement of good uniformity of plasma and film. Here, we propose a new electrode as part of a method to resolve the standing wave effect in the large-area VHF CCP. The electrode is split up a series of strip-type electrodes and the strip-type electrodes and the ground ones are arranged by turns. The standing wave effect in the longitudinal direction of the strip-type electrode is reduced by using the multi-feeding method of VHF power and the uniformity in the transverse direction of the electrodes is achieved by controlling the gas flow and the gap length between the powered electrodes and the substrate. Also, we provide the process results for the growths of the a-Si:H and the ${\mu}c$-Si:H films. The high DR (2.4 nm/s for a-Si:H film and 1.5 nm/s for the ${\mu}c$-Si:H film), the controllable crystallinity (~70%) for the ${\mu}c$-Si:H film, and the relatively good uniformity (1% for a-Si:H film and 7% for the ${\mu}c$-Si:H film) can be obtained at the high frequency of 40 MHz in the large-area discharge (280 mm${\times}$540 mm). Finally, we will discuss the issues in expanding the multi-electrode to the 8G class large-area plasma processing (2.2 m${\times}$2.4 m) and in improving the process efficiency.

• Journal of electromagnetic engineering and science
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• 제9권3호
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• pp.152-158
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• 2009

We have developed a novel digital feedback predistortion(DFBPD) linearization based on RF feedback PD for the wide bandwidth modulated signals. The wideband PD operation is carried out by combining the DFBPD and memory lookup table(LUT). To experimentally demonstrate the linearization performance of the proposed PD technique for wideband signal, a class-AB amplifier using an LDMOSFET MRF6S23140 with 140-W peak envelope power is employed at 2.345 GHz. For a forward-link 2FA wideband code-division multiple-access signal with 10 MHz carrier spacing, the proposed DFBPD with memory LUT delivers the adjacent channel leakage ratio at an 10 MHz offset of -56.8 dBc, while those of the amplifier with and without DFBPD are -43.2 dBc and -41.9 dBc, respectively, at an average output power of 40 dBm. The experimental result shows that the new DFBPD with memory LUT provides a good linearization performance for the signal with wide bandwidth.

• 한국산림과학회지
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• 제107권4호
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• pp.412-421
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• 2018

본 연구는 산림시업이 소나무임분의 수관연료특성 변화에 미치는 영향을 예측하고자 하였다. 본 연구에서는 국가산림자원자료 중 시업지 1,085 stands, 비시업지 349 stands의 표본점 자료를 분석에 이용하였으며, Weibull 함수를 사용하여 시간에 따른 임분생장과 수관연료특성에 대해 예측하였다. 산림시업유무에 따른 수관연료특성을 비교해본 결과 비시업지 임분이 시업지 임분에 비해 평균 수관연료량은 약 14% 높게 나타났으며, 연소가능한 수관연료밀도 또한 약 16% 높게 나타났다. Weibull 함수를 사용하여 임령 40년, 50년, 60년의 생장 예측과 수관연료특성 변화를 비교해본 결과, 시업지 임분은 시간이 지남에 따라 중경목, 대경목에 최대임목본수의 증가가 예측된 반면, 비시업지 임분은 소경목, 중경목에서 최대임목본수가 예측되었다. 비시업지 임분이 시업지 임분에 비해 수관연료량, 수관연료밀도의 증가량이 높게 나타나 수관화로의 확산 가능성이 높은 것으로 사료되었다.

• 한국체육학회지인문사회과학편
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• 제55권3호
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• pp.43-57
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• 2016

이 내러티브 연구는 KAIST부설 한국과학영재학교의 체육교사가 실행했던 체육평가의 경험을 기술하고 그 과정에서 탐색되는 교육적 의미들을 해석하는데 목적이 있다. 연구 참여자는 결정적 사례표집법에 의해서 선정된 두 체육교사이다. 자료수집은 연구 참여자의 공식적 인터뷰를 중심으로 연구자의 필드노트, 비공식적 인터뷰, 각 종 회의록, 학생의 강의평가, 연구자와 연구참여자의 이메일 등을 통해 이루어졌다. 자료의 분석은 귀납적인 범주화 과정을 거쳤으며 연구의 진실성을 확보하기 위해 다각화된 자료의 통합, 동료 연구자에 의한 조언과 지적, 연구텍스트에 대한 연구 참여자의 지속적인 확인과정을 거쳤다. 연구참여자들은 KAIST부설 한국과학영재학교의 체육평가를 실행하면서 간소화된 평가에 따른 체육수업의 질적 발전, 평가결과 정리에 따른 잡무로부터의 해방, 체육에 대한 학생들의 인식개선, 과도한 경쟁이 없는 안전한 수업의 실현, Pass/Fail 평가의 전이가능성 확인과 같은 평가의 효과성을 경험함과 동시에 체육평가의 타당도와 신뢰도 확보에 대한 고민, 체육수업을 하찮게 생각하는 학생의 등장, Fail을 부여할 수 없는 현실과 같은 평가의 한계를 경험하였다. 이러한 두 체육교사의 체육평가 경험은 좋은 체육수업과의 조우, 체육수업 비평으로의 초대, 학생이 주도하는 학교체육문화의 시작이라는 3가지 교육적 의미로 해석되었다.

• 한국정밀공학회지
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• 제30권11호
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• pp.1203-1210
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• 2013

Korea's first Naro-Science small class satellite was launched by Naro launcher in 2013. The structure of the satellite is mostly composed of aluminum honeycomb and frame. The honeycomb structure is homogenized with asymptotic homogenization method and its mechanical properties were used for the numerical analysis. There have been some difficulties to modeling the honeycomb sandwich panels for FEA. In the present study, the mechanical characteristics of the sandwich panel composite were numerically computed and used for the simulation. This methodology makes it easy to overcome the weakness of modeling of complicated sandwich panels. Both an experiment of vibration test and numerical analyses were conducted simultaneously. The analysis results from the current homogenization were compared with that of experiment. It shows a good agreement on the dynamic responses and certified the reliability of the present methodology when manipulate sandwich panel structure.

• 천문학회지
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• 제40권4호
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• pp.83-89
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• 2007

A new type of object called "Very Low Luminosity Objects (VeLLOs)" has been discovered by the Spitzer Space Telescope. VeLLOs might be substellar objects forming by accretion. However, some VeLLOs are associated with strong outflows, indicating the previous existence of massive accretion. The thermal history, which significantly affects the chemistry, between substellar objects with a continuous low accretion rate and objects in a quiescent phase after massive accretion (outburst) must be greatly different. In this study, the chemical evolution has been calculated in an episodic accretion model to show that CO and $N_2H^+$ have a relation different from starless cores or Class 0/I objects. Furthermore, the $CO_2$ ice feature at $15.2{\mu}m$ will be a good tracer of the thermal process in VeLLOs.