• Nuclear Engineering and Technology
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• 제54권7호
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• pp.2702-2713
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• 2022

A steam generator tube rupture accompanying a core damage may cause the fission product to be released to environment bypassing the containment. In such an accident, the steam generator is the major path of the radioactive aerosol release. AEOLUS facility, the scaled-down model of Korean type steam generator, was built to examine the aerosol removal in the steam generator during the steam generator tube rupture accident. Integral and separate effect tests were performed with the facility for the dry and flooded conditions, and the decontamination factors were presented for different tube configurations and submergences. The dry test results were compared with the existing test results and with the analyses to investigate the aerosol retention physics by the tube bundle, with respect to the particle size and the bundle geometry. In the flooded tests, the effect of submergence were shown and the retention in the jet injection region were presented with respect to the Stokes number. The test results are planned to be used to constitute the aerosol retention model, specifically applicable for the analysis of the steam generator tube rupture accident in Korean nuclear power plants to evaluate realistic fission product behavior.

• 한국보육지원학회지
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• 제19권4호
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• pp.29-52
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• 2023

Objective: This research aims to examine the effect of a young children's engineering-focused STEAM program based on the project approach - a program that constructs components aligned with children's interests in their play through an engineering design process - on their scientific inquiry ability, mathematical problem-solving ability, and creativity. Methods: In this research, 42 five-year-old children from a public kindergarten in S district, I city, were randomly divided into experimental and comparative groups, each with 21 children. The engineering-focused STEAM program was conducted from April 18 to June 10, 2022, with the experimental group exploring the 'car' theme and the comparison group focusing on a different theme. The study employed an independent sample t-test and analysis of covariance(ANCOVA), using the pretest as a covariate to control variables. Results: The children-selected 'cars' themed engineering-focused STEAM program was effective in enhancing their scientific inquiry ability, mathematical problem-solving ability and creativity. Conclusion/Implications: The engineering-focused STEAM program, which emerges from young children's interesting daily play, had positive effects on enhancing their scientific inquiry ability, mathematical problem-solving ability, and creativity. This research can serve as fundamental data for developing education programs focused on engineering within the STEAM framework, guided by children's emergent play.

• 대한기계학회논문집B
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• 제33권9호
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• pp.709-717
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• 2009

Heat transfer rate is a very important factor for the performance of a steam reformer because a steam reforming reaction is an endothermic reaction. Coaxial cylindrical reactor is the reactor design which can improve the heat transfer rate. Temperature, fuel conversion and heat flux in the coaxial cylindrical steam reformer are studied in this paper using numerical method under various operating conditions. Langmuir-Hinshelwood model and pseudo-homogeneous model are incorporated for the catalytic surface reaction. Dominant chemical reactions are assumed as a Steam Reforming (SR) reaction, a Water-Gas Shift (WGS) reaction, and a Direct Steam Reforming (DSR) reaction. Although coaxial cylindrical steam reformer uses 33% less amount of catalyst than cylindrical steam reformer, its fuel conversion is increased 10 % more and its temperature is also high as about 30 degree. There is no heat transfer limitation near the inlet area at coaxial-type reactor. However, pressure drop of the coaxial cylindrical reactor is 10 times higher than that of cylindrical reactor. Operating parameters of coaxial cylindrical steam reformer are the wall temperature, the inlet temperature, and the Gas Hourly Space Velocity (GHSV). When the wall temperature is high, the temperature and the fuel conversion are increased due to the high heat transfer rate. The fuel conversion rate is increased with the high inlet temperature. However, temperature drop clearly occurs near the inlet area since an endothermic reaction is active due to the high inlet temperature. When GHSV is increased, the fuel conversion is decreased because of the heat transfer limitation and short residence time.

• 정보교육학회논문지
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• 제18권2호
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• pp.213-224
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• 2014

소프트웨어와 하드웨어를 연계한 STEAM 학습은 알고리즘 향상, 문제해결 능력, 융합적 사고력 등을 크게 신장할 수 있으며, 궁극적으로 학습태도 및 학업 성취력을 높일 수 있다. 본 연구에서는 프로그래밍의 기본 개념을 이해할 수 있는 초등학교 6학년들이 스크래치와 6개의 센서가 부착된 센서 보드를 결합한 프로그래밍 활용으로 국정교과서(5종) 교과내용을 학습 할 수 있도록 학습 모형을 개발하였으며, 6학년 수업현장에서 적용하고 결과를 분석하였다. 결과로서, 평가대상인 초등학생들 대부분이 스크래치와 센서 보드를 결합한 STEAM 학습도구가 적합한 것으로 분석되었다. STEAM 학습에서의 성취도 평가에서 5개 교과 평균성취 수준이 10점 만점에 7점 이상의 평가를 받은 학생들이 39.5%를 얻었으며, 평가대상 대부분의 학생들이 만족할 만한 성취수준을 얻은 것으로 분석되었다. 따라서, 스크래치와 하드웨어인 스크래치 센서 보드를 활용한 학습은 단순히 소프트웨어만 활용하는 기존 소프트웨어 중심의 학습보다 효과적인 것으로 판단된다.

• 연구논문집
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• 통권27호
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• pp.75-86
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• 1997

Combined cycle power plant is a system where a gas turbine or steam turbine is used to produce shaft power to drive a generator for producing electrical power and the steam from the HRSG is expanded in a steam turbine for additional shaft power. Combined cycle plant is a one from of cogeneration. The temperature of the exhaust gases from a gas turbine ranges from $400^\circC$ to $600^\circC$, and can be used effectively in a heat recovery steam generator to produce steam. Combined cycle can be classed as a "topping(gas turbine)" and a "bottoming(steam turbine)" cycle. The first cycle, to which most of the heat is supplied, is called the topping cycle. The wasted heat it produces is then utilized in a second process which operates at a lower temperature level and is therefore referred to as a "bottoming cycle". The combination of gas/steam turbine power plant managed to be accepted widely because, first, each individual system has already proven themselves in power plants with a single cycle, therefore, the development costs are low. Secondly, the air as a working medium is relatively non-problematic and inexpensive and can be used in gas turbines at an elevated temperature level over $1000^\circC$. The steam process uses water, which is likewise inexpensive and widely available, but better suited for the medium and low temperature ranges. It, therefore, is quite reasonable to use the steam process for the bottoming cycle. Only recently gas turbines attained inlet temperature that make it possible to design a highly efficient combined cycle. In the present study, performance analysis of a dual pressure combined-cycle power plant is carried out to investigate the influence of topping cycle to combined cycle performance.

• 과학교육연구지
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• 제42권1호
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• pp.1-11
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• 2018

과학, 기술, 공학, 예술, 그리고 수학을 통합한 STEAM 프로그램은 중등 교육에서 필수적인 요소로 자리 잡았고 소프트웨어 교육은 앞으로 중등학교에서 필수 이수과목으로 선정될 예정이다. 본 연구에서는 STEAM 교육과 함께 소프트웨어 교육 자료로 레고 마인드스톰 로봇 활용방안을 제안하고자 한다. 5차시로 개발된 STEAM 교육 프로그램은 차시별로 STEAM 교육에서의 핵심적인 요소를 포함하여 문제해결중심으로 구성되었고, 이를 수업에 적용하여 사례를 분석하였다. 분석 결과 레고 로봇을 활용한 STEAM 프로그램은 학생들에게 창의적인 사고와 문제해결 방법에 대해 구상 할 수 있는 기회를 제공하고 소프트웨어 교육과 과학 수업에의 활용 가능성에 대해 긍정적인 결과를 보였다. 또한 본 연구에서 개발한 프로그램은 방과 후 수업, 영재수업 등 현장에 적용 가능함을 알 수 있었다.

• Korean Chemical Engineering Research
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• 제54권4호
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• pp.479-486
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• 2016

순산소 전로 후드의 일산화탄소와 열회수를 위해서는 고효율의 증기를 발생시키는 증기드럼의 장착이 필요하다. 그러나 제선 제강공정에서 증기발생은 간헐적이거나 주기적인 산소 취입공정기간에 제한적이다. 따라서, 증기드럼은 전로의 주기에 따른 산소의 취련기간 동안 효율적으로 증기를 발생시키도록 최적 설계되어야 한다. 따라서 본 연구에서는 다양한 운전조건 및 기하학적 형상변화가 증기드럼 내의 열유동 특성과 성능에 미치는 효과를 예측할 수 있는 3차원 전산유체역학 모델을 제안하였다. 본 모델은 유체유동 및 열전달 뿐만 아니라 계면유동에서의 증발 및 응축을 유한체적법을 사용하여 고려하였다. 본 모델의 예측성능을 검증하기 위하여 실험에서 구한 증기발생량과 비교하였으며 3.2%의 상대오차를 보였다.

• 디지털융복합연구
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• 제15권1호
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• pp.547-557
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• 2017

이 연구는 중학생을 중심으로 3D 프린팅과 체육 중심 STEAM프로그램이 중학생의 교과흥미도 및 창의적 태도에 미치는 영향을 실증적으로 구명하는데 목적이 있다. 이에 따른 연구대상은 경기도 소재 중학생을 대상으로 실험집단 98명과 비교 101명을 중심으로 사전 사후검사를 통해 교과흥미도와 창의성 태도에 대한 자료를 수집하였다. 자료분석은 통계프로그램인 SPSS 23.0 프로그램을 활용하여, 탐색적 요인분석, 신뢰도 분석 그리고, 종속표본 t검증과 독립표본 t검증 실시하였다. 이러한 과정을 통해 얻은 결론은 다음과 같다. 첫째, 3D 프린터를 활용한 체육 중심 STEAM 프로그램은 교과흥미도에 효과적이었다. 둘째, 3D 프린터를 활용한 체육 중심 STEAM프로그램은 창의적 태도에 효과적이었다.

• 한국실내디자인학회논문집
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• 제26권6호
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• pp.97-105
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• 2017

Korea is promoted STEAM education since 2011. Furthermore, in high school education, based on the in-depth elective course's teaching and learning contents of science. The STEAM program can improve students' competence because it encourages to self-directed learning through the vocational project performance. Therefore, in this study, we researched a design education program for the experience of fusion and complex design based on STEAM education concept. We developed an education program to design insulation wall systems using up-cycling concepts to increase energy efficiency. As a result, the characteristics of the fusion education and the theoretical study about the learner-centered education curriculum, the analysis of the high school curriculum, the STEAM elements, The program was revised and supplemented through consultation with STEAM experts. In addition, the developed program was applied to high school students, and each step were analyzed based on the educational method theory. The following results were obtained. First, this study presented a program to cope with the needs of high school intensive education. Second, it provided learning motivation by combining flipped-learning as a way to train STEAM education contents. Third, it is required to develop differentiated and continuous program development and data sharing Fourth, in order to operate and promote the future environment design STEAM school, it is necessary to expand educational programs for high school students in the region through linkage with various universities.

• 자원리싸이클링
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• 제16권6호
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• pp.28-33
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• 2007

예로부터 중요한 에너지원인 석탄은 화석연료 중 가장 풍부하며 세계 각지에 골고루 분포되어 있다. 저급연료인 석탄을 보다 효율적으로 활용하기 위하여서 직접 연소에 의한 에너지 획득뿐 아니라 열분해 및 가스화를 통한 청정 고부가 가치의 연료로 전환기술이 개발되고 있다. 석탄 가스화를 통하여 생성된 합성가스는 전기 생산 및 화학물질의 합성 등 여러 가지 방법으로 활용이 가능하며, 공해물질 발생저감 및 에너지 이용효율 증가를 위하여 석탄 가스화 기술이 계속적으로 발전되고 있다. 석탄의 가스화는 steam, 공기, 질소 등을 agent로 이용하게 되는데, 주로 steam이 gasification agent로 이용되고 있으며, 이 때 생성가스의 특성은 가스화기의 온도, 압력 그리고 steam/carbon 비에 의해서 결정되게 된다. 본 연구에서는 초고온의 steam을 이용하여 석탄의 가스화를 수행하고 steam/carbon 비에 따라 생성된 $H_2$, $CH_4$, Co 그리고 $CO_2$ 등의 가스특성 및 tar, ammonia, cyan과 같은 부산물의 생성에 대하여 연구를 수행하였다.