• Restorative Dentistry and Endodontics
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• 제45권2호
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• pp.13.1-13.10
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• 2020

Objective: The aim of this study was to evaluate the influence of different modeling agents on the surface microhardness (Vickers hardness number; VHN), roughness (Ra), and color change (ΔE) of a nano-hybrid composite with or without exposure to discoloration by coffee. Materials and Methods: Sixty-four cylinder-shaped nano-hybrid composite specimens were prepared using a Teflon mold. The specimens' surfaces were prepared according to the following groups: group 1, no modeling agent; group 2, Modeling Liquid; group 3, a universal adhesive (G-Premio Bond); and group 4, the first step of a 2-step self-adhesive system (OptiBond XTR). Specimens were randomly allocated into 2 groups (n = 8) according to the storage medium (distilled water or coffee). VHN, Ra, and ΔE were measured at 24 hours, 1 week, and 6 weeks. The Kruskal-Wallis test followed by the Bonferroni correction for pairwise comparisons was used for statistical analysis (α = 0.05). Results: Storage time did not influence the VHN of the nano-hybrid composite in any group (p > 0.05). OptiBond XTR Primer application affected the VHN negatively in all investigated storage medium and time conditions (p < 0.05). Modeling Liquid application yielded improved Ra values for the specimens stored in coffee at each time point (p < 0.05). Modeling Liquid application was associated with the lowest ΔE values in all investigated storage medium and time conditions (p < 0.05). Conclusion: Different types of modeling agents could affect the surface properties and discoloration of nano-hybrid composites.

• 한국수학교육학회지시리즈A:수학교육
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• 제55권1호
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• pp.41-71
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• 2016

The purpose of this study is to investigate elementary students' communication in process of applying mathematical modeling. For this study, 22 fifth graders in an elementary school were observed by applying mathematical modeling process (presentation of problem ${\rightarrow}$ model inducement activity ${\rightarrow}$ model exploration activity ${\rightarrow}$ model application activity). And the level of their communication with their activity sheets and outputs, observation records and interviews were also analyzed. Additionally, by analyzing the activity cases of and , this study researched that what is a positive influence on students' communication skills. Whereas showed significant advance in the level of communication, who communicated actively on speaking area but not on every areas showed insensible changes. To improve communication abilities, cognitive tension and debate situation are needed. This means, mathematical education should continuously provide students with mathematical communication learning, and a class which contains mathematical communication experiences (such as mathematical modeling) will be needed.

• 한국지능시스템학회논문지
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• 제14권2호
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• pp.195-200
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• 2004

컴퓨터 게임은 보이드들의 군집 행동 모델링을 위하여 플로킹이라는 지능적인 기법을 사용하고 있다. 플로킹은 약간의 컴퓨터 자원만을 이용하여 조류나 물고기와 같은 예측할 수 없는 형태의 군집 행동 패턴을 자연스럽게 모델링 할 수 있다. 단 논문에서 우리는 사실적인 수중 생태계 군집 행동 모델링을 위하여, 포식자 및 먹이로 구성되는 생태계를 구현하였다. 또한 퍼지 논리를 생태계 요소들의 본능적인 욕망을 구현하기 위하여 적용하였다 그 결과 본 모델은 생태계의 파괴를 극복하고, 자연스럽게 생태계 행동을 모델링 할 수 있다는 것을 확인하였다.

• 한국태양에너지학회 논문집
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• 제28권4호
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• pp.56-61
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• 2008

The modeling of PV (Photovoltaic) module is useful to perform detailed analysis of PV system performance for changing meteorological conditions, verify actual rated power of PV system sizing and determine the optimal design of PV system and components. This paper indicates a modeling approach of PV module performance in terms of meteorological conditions and identifies validity of this modeling method by comparing measured with simulated value of various PV modules using simulation model.

• 아동학회지
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• 제11권1호
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• pp.87-99
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• 1990

The present study was designed to investigate the effect of altruistic TV viewing and verbal training on the altruistic behavior of preschoolers. The subjects of this study were a total of 56 boys and 57 girls from a kindergarten in Kwachon, Kyung-gi do. The subjects were assigned to one of three conditions: in the first condition subjects were shown video tapes designed to portray prosocial themes (TV modeling group) ; in the second condition subjects saw the video tapes in addition to verbal training (TV modeling plus verbal training group); in the third condition subjects received neither TV modeling nor verbal training (control group). Statistical analysis was by ANOVA and $Scherr\acute{e}$ test. Significant differences were found in altruistic behavior between the TV modeling and the TV modeling with verbal training groups.

• 지식경영연구
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• 제20권2호
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• pp.1-24
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• 2019

This tutorial introduces procedures and methods for performing structural equation modeling using R. To do this, we present advanced analysis methods based on structural equation model such as mediation effect analysis, moderation effect analysis, moderated mediation effect analysis, and multiple-group analysis with R program code using R lavaan package that supports structural equation modeling. R is flexible and scalable, unlike traditional commercial statistical packages. Therefore, new analytical techniques are likely to be implemented ahead of any other statistical package. From this point of view, R will be a very appropriate choice for applying new analytical techniques or advanced techniques that researchers need. Considering that various studies in the social sciences are applying structural equations modeling techniques and increasing interest in open source R, this tutorial is expected to be useful for researchers who are looking for alternatives to existing commercial statistical packages.

• 한국과학교육학회지
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• 제36권3호
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• pp.361-369
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• 2016

이 연구에서는 중학생들의 과학적 모형 구성 활동을 적용한 수업에서 나타나는 소집단 토론과 전체 학급 토론의 특징을 분석하였다. 서울특별시에 소재한 중학교의 1학년 학생들을 대상으로 GEM 순환 과정에 따라 구성한 과학적 모형 구성 활동을 적용한 수업을 진행하였다. 소집단 토론 및 전체 학급 토론을 생각 드러내기, 생각 비교하기, 결론 이끌어내기의 세 단계로 분류하여 단계별 특징을 분석하였으며, 그 과정에서 나타나는 논증의 수준도 분석하였다. 연구 결과, 학생들은 소집단 토론에서 구성원 각자의 개인 모형으로부터 공통점을 추출하여 소집단 모형을 생성하였고, 전체 학급 토론에서 소집단 모형들간의 차이점을 논의하면서 소집단 모형을 평가하고 수정하였다. 이에 따라 소집단 토론에서는 생각 드러내기 단계가 중심이었고 전체 학급 토론에서는 생각 비교하기 단계가 중심이었다. 소집단 토론과 전체 학급 토론에서 일어나는 논증의 수준은 전반적으로 높지 않았으나, 과학적 모형 구성 활동에 대한 학생들의 인식과 흥미가 높아 적극적으로 수업에 참여하였다. 그 결과, 과학적 모형 구성 활동이 학생들의 개념 변화에 긍정적인 영향을 미친 것으로 나타났다. 이러한 연구 결과를 바탕으로 과학적 모형 구성 활동을 적용한 수업을 효과적으로 진행하기 위한 방안에 대해 논의하였다.

• 대한치과기공학회지
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• 제36권2호
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• pp.83-89
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• 2014

Purpose: This study is to evaluate the effect of modeling liquid on the shear-bond strength between zirconia core and veneering ceramic. Methods: Disk-shaped (diameter: 12.0mm; height: 3.0mm) zirconia were randomly divided into six groups according to the surface conditioning method and whether modeling liquid is used or not to be applied (N=60, n=10 per group): group 1-control group with distilled water(ZD); group 2-control group with modeling liquid(ZM); group 3-airborne particle abrasion with $110-{\mu}m$ $Al_2O_3$(AD) with distilled water; group 4-airborne particle abrasion with $110-{\mu}m$ $Al_2O_3$ with modeling liquid(AM); group 5-liner with distilled water(LD); group $6{\pounds}{\neq}liner$ with modeling liquid(LM). Contact angles were determined by the sessile drop method at room temperature using a contact angle measurement apparatus. The specimens were prepared using dentin veneering ceramics, veneered, 3mm high and 2.8mm in diameter, over the cores. The shear bond strength test was performed in a Shear bond test machine. Load was applied at a cross-head speed of 0.50mm/min until failure. The fractured zirconia surfaces were evaluated by using stereomicroscope (${\times}30$). Collected data were analyzed using SPSS(Statistical Package for Social Sciences) Win 12.0 statistics program. Results: ZD showed the highest contact angle($50.6{\pm}5.4^{\circ}$) and LD showed the lowest value($6.7{\pm}1.3^{\circ}$). Control groups and zirconia liner groups were significantly higher contact angle than liner groups(p<0.05). LD was the highest shear bond strength($43.9{\pm}3.8MPa$) and ZD was the lowest shear bond strength($24.8{\pm}4.9MPa$). Shear bond strengths of control groups and contact angle of liner groups were not significantly different((p>0.05). Liner groups presented adhesive failures. The others groups showed cohesive and adhesive failures. Conclusion: Modeling liquid groups showed lower contact angles and lower shear bond strength compared to those of distilled water groups.

• 한국과학교육학회지
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• 제40권2호
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• pp.127-140
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• 2020

본 연구에서는 명시적-반성적 접근을 활용한 모델링 수업이 초등학생들의 메타모델링 지식 이해에 미치는 영향을 탐색했다. 연구를 위해 서울 J 초등학교 4학년 2개의 학급을 선정하여 각 학급을 실험반과 통제반으로 선정하였다. 실험반에서는 명시적-반성적인 방법으로 모델링 수업을 5차시 동안 진행하였으며, 통제반에서는 4차시 동안 암시적 방법으로 모델링 수업을 진행하였다. 수업 사전·사후에 메타모델링 지식 다섯 가지 요소인 '모델의 의미, 목적, 설계와 구성, 가변성, 다중성'에 대해 설문 및 면담을 수행하였다. 연구 결과 메타모델링 지식 요소 중 실험반에서는 '모델의 의미(모델의 예)', '모델의 목적', '모델의 가변성', '모델의 다양성' 영역에 대한 이해가 높아지는 변화가 나타났지만, 통제반에서는 여전히 모델의 의미를 파악하지 못하는 학생이 다수였으며 모델과 모델링의 본성에 대해 다양하고 폭넓은 이해가 아닌 모델링 수업과 관련된 제한된 이해에 머물렀다. 본 연구를 통해 명시적-반성적 메타모델링 지식을 강조한 모델링 수업이 초등학생들의 메타모델링 지식 변화에 긍정적인 영향을 미침을 알 수 있었다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 D
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• pp.2684-2686
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• 2000

This paper describes a preliminary study on a modeling technique for control performance evaluation of asynchronous TMR(Triple Modular Redundancy) controller. Hybrid system modeling is applied to TMR controller performance evaluation and mixed logical dynamical system description is used to model the behavior of majority voter in the controller. Windup and bumpless transfer problems in redundancy controls are also mentioned.