• 한국지능시스템학회:학술대회논문집
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• 한국퍼지및지능시스템학회 2003년도 ISIS 2003
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• pp.358-363
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• 2003

Optimal tuning plays an important role in operations or tuning of the complex process such as the main steam temperature of the thermal power plant. However, it is very difficult to maintain the steam temperature of power plant using conventional optimization methods, since these processes have the time delay and the change of the dynamic characteristics in the reheater. Up to the present time, the Pm controller has been used. However, it is not easy to achieve an optimal PID gain with no experience, since the gain of the PID controller has to be manually tuned by trial and error. This paper suggests immune algorithm based tuning technique for PID Controller on steam temperature process with long dead time and its results are compared with genetic algorithm based tuning technique.

• 대한기계학회논문집B
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• 제26권10호
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• pp.1370-1377
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• 2002

This study analyzed the design performance of the bottoming system of combined cycle power plants using a once-through heat recovery steam generator. For a parallel arrangement of the main heater and reheater, parametric analyses were carried out to present the criteria for determining the reheater pressure and the location of the starting point of the reheater in the HRSG. The performance of the bottoming system was presented fer a range from high subcritical to supercritical pressure. The steam turbine power is as high as that of conventional triple-pressure bottoming systems. The serial arrangement of heat exchangers with division of each heater into several segments can achieve similar power level.

• 한국연소학회지
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• 제16권3호
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• pp.1-11
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• 2011

The main objective of this paper is to investigate characteristic of steam reformer at various geometries and operating conditions. In this paper, the steam reforming is studied by a numerical method and three dimensional simulations were used for effective analytical study. User - Defined Function (UDF) was used to simultaneously calculate reforming and combustion reaction. And the numerical model is validated with experimental results at the same operating conditions. In order to understand the relationship between operating conditions such as gas hourly space velocity(GHSV), mass flow rate of combustor inlet, various numerical investigations are carries out for various geometries. Numerical results show that cylindrical geometry is more effective than rectangular geometry for heat transfer to reactors and reforming efficiency. As mass flow rate of combustor inlet increase, reaction occurs more faster and temperature increase with each geometry. On the other hand, reaction and hydrogen conversion decrease as mass flow rate of reactor decreases.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 추계학술대회논문집B
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• pp.867-871
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• 2001

The main reason for reviewing the condensate water return system in the auxiliary steam system is to obtain the thermal high efficiency of the power plant and thus save the fossil energy in power plant. This study intends to analyze the thermal efficiency of the power plant and predict the increasing in the generator output by the return system reformation of auxiliary steam line in the thermal power plant.

• 동력기계공학회지
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• 제11권1호
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• pp.45-50
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• 2007

Acoustic emission technology is applied to diagnosis the internal leak and operating conditions of the major valves at nuclear power plants. The purpose of this study is to verify availability of the acoustic emission as in-situ diagnosis method. In this study, acoustic emission tests are performed when the pressurized high temperature steam flowed through gate valve(1st stage reheater valve) and glove valve(main steam dump valve) on the normal size of 4 and 8". The valve internal leak diagnosis system for practical field was designed. The acoustic emission method was applied to the valves at the site, and the background noise was measured for the abnormal plant condition. To improve the reliability, a judgment of leak on the system was used various factors which are AE parameters, trend analysis, signal level analysis and RMS(root mean square) analysis of acoustic signal emitted from the valve operating condition internal leak.

• Nuclear Engineering and Technology
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• 제33권6호
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• pp.585-595
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• 2001

A series of experiments have been carried out to investigate the effects of non-condensable gas on the direct contact film condensation of vapor mixture under an adiabatic wall condition. The average heat transfer coefficient of the direct contact condensation was obtained at the atmospheric pressure with four main parameters ; air-mass fraction, mixture velocity, film Reynolds number, and the degree of water film subcooling having an influence on the condensation heat transfer coefficient. With the analysis of 88 experiments, a correlation of the average Nusselt number for direct contact film condensation of steam/air mixture at an adiabatic vertical wall was proposed as functions of film Reynolds number, mixture Reynolds number, air mass fraction, and Jacob number. The average heat transfer coefficient for steam/air mixture condensation decreased significantly while air mass fraction increased. The average heat transfer coefficients also decreased as the Jacob number increased, and were scarcely affected by the film Reynolds number below a mixture Reynolds number of about 245,000.

• 한국압력기기공학회 논문집
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• 제6권2호
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• pp.1-8
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• 2010

Nuclear steam generator tubes have experienced wear degradation at tube support structure. Morphology of wear scar was analyzed by using eddy current signal. A burst test facility for steam generator tubes was established and tubes with 3 types of defects were tested. The burst test results show that the depth of wear scar is the main factor influencing the burst pressure of tubes, meanwhile, both the longitudinal length and the angle also have effect on the burst pressure. Based on test results, the burst pressure equation for wear degradation was proposed.

• 한국초등과학교육학회지:초등과학교육
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• 제33권3호
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• pp.439-452
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• 2014

The purpose of this study is to find out the effect of STEAM program on the scientific communication skills and the learning flow of elementary gifted students. The main findings of this study are as follows: First, STEAM program that mathematical, technical, engineering and art factors were combined based on basic concepts of science were developed. Seconds, the change in the scientific communication skills of experimental group applying STEAM program had statistically meaningful difference (p<.05). Third, the flow of experimental class improved, but it had no meaningful difference statistically (p>.05). But it is expected that continuing level adjusted STEAM program might have positive effect on improving the flow with the following three reasons: 1) The gifted students' flow level on learning before experiment was rather too high to expect short term effect. 2) It was hard for them to achieve flow experience because topic difficulties and students' capacities were not balanced. 3) topic commitments and autotelic behaviors of gifted students were observed during classes. Fourth, by the result of the student satisfaction questionnaire survey on this program, students actively participated in the STEAM program with interest and curiosity. As achieved self-directed problem solving, versatile communication activities and success experiences, their class satisfaction was high. Based on such results, it was expected that the gifted class applied of STEAM program could enhance scientific communication capacity of the elementary gifted students and would further positively influence flow of learning as well. In addition, it was considered to have integrated approach value to elementary gifted and talented education in the aspect that it could satisfy various educational demands of gifted students.

• 정보교육학회논문지
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• 제22권3호
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• pp.325-333
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• 2018

본 연구는 플립 러닝을 활용하여 SW 융합 교육을 적용하였을 때 학생들의 학습동기를 분석한 것이다. 연구의 주요내용은 SW 교육을 기존 교과와 융합한 프로그램을 개발하고, 방법적인 측면으로 플립 러닝을 활용하였다. 초등학생들을 대상으로 교육 프로그램을 적용하였으며 사전 사후 학습동기 검사를 실시하였다. 연구 분석 결과, 플립 러닝을 활용한 SW 융합 프로그램은 학생들의 학습동기 요소에서 주의집중도, 관계향상도, 자신감이 향상되었다. 본 연구에서 개발된 SW 융합 교육 프로그램과 연구 분석 결과가 SW 교육의 발전에 도움을 주고, 교육 현장에 안착하기 위한 자료로 유용하게 활용되길 기대한다.

• 대한지구과학교육학회지
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• 제17권2호
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• pp.168-180
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• 2024

이 연구에서는 천문·우주의 디지털 자료를 중심으로 한 STEAM 프로그램을 개발하고, 무선 표집된 초등학교 6학년 학생 167명에게 적용하여 창의적 문제해결력 향상을 위한 STEAM 프로그램의 수업 효과를 알아보고자 하였다. 이 연구의 결과는 다음과 같다. 첫째, 창의적 문제해결력에 대한 STEAM 프로그램의 수업 전·후 통계적 검정에서 유의미한 결과를 나타내었다(p < .05). 이는 디지털 중심의 문제 해결 과정에서 학생들이 융합적 사고와 아이디어 생성의 절차적 과정을 통해 STEAM 프로그램이 창의적 문제해결력 향상에 도움을 주었음을 시사한다. 둘째, STEAM 태도 검사의 사전·사후 점수 차이에 의한 대응표본 t-검정에서 모든 항목에서 유의미한 결과가 나타났다(p <.05). 디지털 수업 자료를 분석하고 픽셀아트 작품 제작을 통한 발표 과정을 통해 흥미, 소통, 유용성 등에서 STEAM 태도에 긍정적인 영향을 미친 것으로 판단되며, 이는 향후 첨단 기술을 활용한 융합 교육 프로그램 개발의 필요성을 강조한다. 셋째, STEAM 프로그램 적용 후에 실시한 수업 만족도 검사에서는 '만족도' 구인은 평균 3.55, '흥미'는 3.35, 그리고 '수업 전반의 난이도'는 3.46을 나타내었으며, 기존 수업과의 차이점으로는 '미래 사회 직업정보 획득'이 강조되었다. 다만, 디지털 변환과 해석 과정에서 수업의 흥미도가 다소 낮아진 부분을 고려하여, 향후 수업에서는 체험 활동을 고려한 적절한 수업시수 배분이 필요할 것으로 판단되며, 향후 개발된 프로그램의 일반화를 위해 다양한 학교급, 적용 시기, 난이도를 고려한 후속 연구가 필요할 것이다.