• 대한수학교육학회지:수학교육학연구
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• 제24권3호
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• pp.333-357
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• 2014

본 연구에서 제시하는 무게중심 확인실험 프로그램개발은 2013년 '동국대학교 과학영재교육원'에서 융합형 영재프로그램으로 개발되어 초등 영재학생 10개 집단 120명과 중등수학영재학생 24명을 대상으로 진행되었다. 무게중심 확인실험은 한국 과학창의재단에서 제시하는 융합형인재교육(STEAM) 학습준거 틀에서 수행된 3단계 과정을 이행하여 창의적 융합교육의 효과를 극대화하였다. 본 연구가 갖는 3가지 특징은 다음과 같다. 첫째, 연구에서 새롭게 개발된 무게중심 확인실험은 수학과 물리가 융합된 교육방식이다. 둘째, 실험에 사용되는 모형은 학생들의 능동적 활동으로 창의적인 모형 설계가 가능하다. 셋째, 무게중심 확인실험 프로그램은 학습 능력에 따라 수준별 수업으로서 전환이 가능하다. 위에서 제시한 특성들을 바탕으로 무게중심 확인실험을 통하여 창의적 융합교육의 효과를 극대화시킨다. 설문조사 결과는 주어진 지식을 단순 암기하는 학습에서 벗어나 실험에 필요한 배경지식 이해, 실험 설계, 실험 과정, 실험 결과의 단계를 거쳐 학습된다. 설문조사와 학생들의 실험 후 토의 결과, 현재 수학 또는 과학 교육과정이 제시하는 무게중심 학습과 비교하여, 새롭게 개발된 융합형 프로그램이 교육의 효과가 뛰어남을 보여 준다. 본 연구는 수학이 다른 교과영역과 융합되는 새로운 융합형 교육방식을 제시한다. 특히 무게중심을 찾고 이를 확인하는 새로운 형태를 제시한다. 결론적으로 교수자와 학습자가 모두 만족할 수 있는 새로운 무게중심 교육의 틀을 제시한다.

• Asian-Australasian Journal of Animal Sciences
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• 제31권6호
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• pp.859-863
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• 2018

Objective: Since very little information exists about the topic; in this experiment we compare, in a long-term finishing program, the growth-performance responses and carcass characteristics of Holstein steers where non-structural carbohydrate concentration of the diet is reduced from 64% to 51% (dry matter basis). Methods: Sixty Holstein steer calves ($129{\pm}2.2kg$) were blocked by initial weight into five groups and randomly assigned within weight groupings to 10 pens. Calves were fed with a steam-flaked corn-based finishing diets containing 51% higher fiber (HF) or 64% lower fiber (LF) nonstructural carbohydrates. Non-structural carbohydrates concentrations were manipulated substituting dried distiller grain with solubles and alfalfa hay for flaked corn. Cattle were weighed every 112 days and at the end of the experiment (day 308) when the cattle were harvested and carcass characteristics were evaluated. Results: Steers fed the HF diet showed improvement (8.8%) in average daily gain (ADG) during the initial 112-d period. This effect was followed by a numerical trend for greater ADG throughout the remainder of the study so that overall ADG tended to be greater (4.9%, p = 0.06) for the HF than for LF. There were no treatment effects on dry matter intake. Gain efficiency and estimated dietary net energy (NE) were greater 8.3% and 5.2%, respectively for HF during the initial 112-d period. Overall (308-d) gain efficiency and estimated dietary NE were similar for both dietary treatments. However, due to differences in tabular dietary NE, the ratio of observed:expected dietary NE tended to be greater (4.1%, p = 0.06) for the HF vs LF diet. There were no treatment effects on carcass characteristics except for a tendency toward a slightly greater (0.5%, p = 0.09) estimated carcass yield. Conclusion: Reducing the non-structural carbohydrate concentration of a conventional steam-flaked corn-based growing finishing diet for Holstein steers can effectively enhance growth performance, particularly during the early growing and late finishing phases.

• 정보교육학회논문지
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• 제21권1호
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• pp.57-66
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• 2017

최근 빅데이터 분석과 함께 사회연결망에 대한 관심이 증대되고 있다. 이러한 사회연결망분석을 이용한 연구가 사회과학 영역뿐 아니라 자연과학 영역 등 여러 분야에서 다양하게 이루어지고 있다. 이에 본 논문에서는 정보교육 관련 석 박사 학위논문을 수집하여 텍스트분석과 사회연결망분석을 실시하였다. 그 결과, 모든 기간에서 출현빈도수가 높게 나오거나 지속적으로 나오는 단어가 있었으며, 기간별로 출현빈도가 갑자기 높아진 단어들도 있었다. 또한, 출현빈도수가 큰 단어가 대체적으로 매개중심성도 컸으며, 기간별 연구흐름의 특징이 있음도 알 수 있었다. 그러므로 IT 기술발전과 초 중 고등학교 정보교육과정 변화에 민감하게 정보교육 석 박사학위 논문 주제가 변화되었음을 알 수 있었다. 앞으로 기간4에서 출현빈도가 높아진 스마트, 모바일, 스마트폰, SNS, 어플리케이션, 스토리텔링, 다문화, STEAM과 관련된 연구가 지속될 것으로 예측하며, 로봇, 프로그래밍, 코딩, 알고리즘, 창의성, 상호작용, 개인정보보호와 관련된 주제도 꾸준히 연구될 것으로 예측된다.

• 한국자동차공학회논문집
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• 제21권6호
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• pp.81-91
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• 2013

A novel design process of a parallel multi-flow type air-cooled condenser of a dual-loop waste heat recovery system with Rankine steam cycles for improving the fuel efficiency of gasoline automobiles has been investigated focusing on reduction of the pressure drop inside the micro-tubes. The low temperature condenser plays a role to dissipate heat from the system by condensing the low temperature loop working fluid sufficiently. However, the refrigerant has low evaporation temperature enough to recover the waste from engine coolant of about $100^{\circ}C$ but has small saturation enthalpy so that excessive mass flow rate of the LT working fluid, e.g., over 150 g/s, causes enormously large pressure drop of the working fluid to maintain the heat dissipation performance of more than 20 kW. This paper has dealt with the scheme to design the low temperature condenser that has reduced pressure drop while ensuring the required thermal performance. The number of pass, the arrangement of the tubes of each pass, and the positions of the inlet and outlet ports on the header are most critical parameters affecting the flow uniformity through all the tubes of the condenser. For the purpose of the performance predictions and the parametric study for the LT condenser, we have developed a 1-dimensional user-friendly performance prediction program that calculates feasibly the phase change of the working fluid in the tubes. An example is presented through the proposed design process and compared with an experiment.

• 수산해양기술연구
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• 제49권1호
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• pp.58-66
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• 2013

Most of steam power plant in Korea are heating the feed water system to prevent freezing water flowing in the pipe in winter time. The heating system is operated whenever the ambient temperature around the power plant area below 5 degree Centigrade. But this kind of heat supplying system cause a lot of energy consuming. If we think about the method that the temperature of the each pipe is controled by attaching the temperature measuring sensor like RTD sensor and heat is supplied only when the outer surface temperature of the pipe is under 5 degree Centigrade, then we can save a plenty of energy. In this study, the computer program package for simulation is used to compare the energy consumption load of both systems. Energy saving rate is calculated for the location of Youngweol area using the data of weather station in winter season, especially the January' severe weather data is analyzed for comparison. Various convection heat transfer coefficients for the ambient air and the flowing water inside the pipe was used for the accurate calculation. And also the various initial flowing water temperature was used for the system. Steady state analysis is done previously to approximate the result before the simulation. The result shows that the temperature control system using RTD sensor represents the high energy saving effect which is more than 90% of energy saving rate. Even in the severe January weather condition, the energy saving rate is almost 60%.

• Nuclear Engineering and Technology
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• 제27권1호
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• pp.53-66
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• 1995

현재 사용중인 Non-LOCA 해석용 인허가 코드들은 특정한 형태의 가압경수로에 맞게 짜여진 것들이어서 모든 형태의 가압 경수로에 적용할 수 있는 범용 코드의 개발이 필요한 실정이다. 이를 위하여 한국원자력연구소에서는 웨스팅하우스 및 CE형 발전소에 공히 적용할 수 있는 과도현상 해석 코드인 TASS 로드를 개발하고있다. 이 TASS 코드는 실시 간 보다 빠르게 핵증기계통에 대한 모의 계산을 수행하며 대화식의 입출력을 통하여 사용자가 원하는 과도현상을 정확히 모사할 수 있다. 본 논문에서는 웨스팅하우스형 발전소에 대하여 TASS 코드를 적용하여 Non-LOCA 인허가 해석을 하기 위한 검증을 위해, 교류 전원 상실사고와 부하상실사고에 대하여 발전소 실측자료와의 비교계산을 수행하였고 주급수관 파단사고, 펌프축 고착사고, 증기발생기 세관 파열사고 및 주증기관 파단사고들에 대하여 대형코드인 RELAP5 /MOD3 코드와의 비교계산을 수행하였다.

• 사물인터넷융복합논문지
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• 제4권1호
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• pp.23-29
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• 2018

본 연구는 국내 융합기술 관련 연구물의 네트워크 분석을 통해 연구동향을 파악하고, 연구특성과 구조, 현황을 분석하는데 목적이 있다. 이를 위해 지난 13년(2005년~2018년)동안 연구명에 '융합기술' 단어를 사용한 학술지 177편의 저자키워드 653개에 대한 네트워크 분석을 실시하였다. 연구결과는 다음과 같다. 첫째, 국내 융합기술 연구는 지난 13년 동안 꾸준히 수행되어 왔으며 주로 융합, 디지털, 기술, 예술디자인 분야에서 활발히 이루어졌다. 둘째, 검색어 빈도분석 결과, '융합기술', '기술융합', '융합', '디자인', '융합교육', 'STEAM', '융합연구', '4차 산업혁명', '특허분석' 등이 융합기술의 주요 키워드로 사용되었다. 셋째, 커뮤니티 분석결과, 5개의 커뮤니티가 분류되었고, 검색어의 특성을 반영해 '나홀로 IT', '융합콘텐츠를 활용한 문화산업', '기술혁신과 연구분석', '융합교육', '기술융합과 특허개발'의 주제가 도출되었다. 이러한 연구결과를 통해 미래사회 융합기술교육 연구의 과제와 방향을 제안하였다.

• 한국재료학회지
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• 제29권5호
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• pp.328-335
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• 2019

Nb-doped $TiO_2$(NTO) coated NiCrAl alloy foam for hydrogen production is prepared using ultrasonic spray pyrolysis deposition(USPD) method. To optimize the size and distribution of NTO particles based on good physical and chemical stability, we synthesize particles by adjusting the weight ratio of the Nb precursor solution(5 wt%, 10 wt% and 15 wt%). The morphological, chemical bonding, and structural properties of the NTO coated NiCrAl alloy foam are investigated by X-ray diffraction(XRD), X-ray photo-electron spectroscopy(XPS), and Field-Emission Scanning Electron Microscopy(FESEM). As a result, the samples of controlled Nb weight ratio exhibit a common diffraction pattern at ${\sim}25.3^{\circ}$, corresponding to the(101) plane, and have chemical bonding(O-Nb=O) at 534 eV. The NTO particles with the optimum weight ratio of N (10 wt%) show a uniform distribution with a size of ~18.2-21.0 nm. In addition, they exhibit the highest corrosion resistance even in the electrochemical stability estimation. As a result, the introduction of NTO coated NiCrAl alloy foam by USPD improves the chemical stability of the NiCrAl alloy foam by protecting the direct electrochemical reaction between the foam and the electrolyte. Thus, the optimized NTO coating can be proposed for excellent protection of NiCrAl alloy foam for hydrocarbon-based steam methane reforming(SMR).

• Nuclear Engineering and Technology
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• 제53권5호
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• pp.1436-1445
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• 2021

To obtain the dynamic characteristics of reactor secondary circuit under transient conditions, the system analysis program was developed in this study, where dynamic models of secondary circuit were established. The heat transfer process and the mechanical energy transfer process are modularized. Models of main equipment were built, including main turbine, condenser, steam pipe and feedwater system. The established models were verified by design value. The simulation of the secondary circuit system was conducted based on the verified models. The system response and characteristics were investigated based on the parameter transients under emergency shutdown and overload. Various operating conditions like turbine emergency shutdown and overspeed, condenser high water level, ejector failures were studied. The secondary circuit system ensures sufficient design margin to withstand the pressure and flow fluctuations. The adjustment of exhaust valve group could maintain the system pressure within a safe range, at the expense of steam quality. The condenser could rapidly take out most heat to avoid overpressure.

• 항공우주시스템공학회지
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• 제1권2호
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• pp.6-12
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• 2007

Flight modes of automatic flight control system for light general aviation flight deck. Garmin G1000, were realized using Stateflow. In developing aircraft, it is difficult to verify the operational flight program in particular branch statement because developer can not see any visual logical steam. So, Stateflow has been used to visualize logical stream, transition from one flight mode to another flight mode. The performance was approved by applying flight mode transition conditions of G1000 to proposed transition system that is composed of states, switches, events, data and transition conditions. DURMI-II was used as 6-DOF simulation model.