• 한국학교ㆍ지역보건교육학회지
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• 제12권3호
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• pp.17-28
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• 2011

Backgroud & Objectives: The purpose of the study was to develop an innovative blended learning method on life style and health promotion and evaluate the educational effects for university students. Methods: The blended learning was developed to combine face-to-face lecture(off-line lecture) and on-line lecture that applied the subject of life style and health promotion. This course is a coordinated effort towards providing 5 topics of lifestyle such as smoking, alcohol, exercise, diet, and stress management. This has been verified by an expert in the field of nursing, education, e-learning technician and students. Participants were different part of university students (n=28) with major enrolled in a general culture course for 2 credits which composed of 8 sessions of each 2-hour in the first semester of 2010. The study was a one group posttest design. A self-report about health knowledge, attitude, and health behavior was organized by content analysis after the sessions. Results: Positive feedbacks from students were reflected in the outcome. Student regarded good lifestyle as being the most important. Student concerned those on-line lectures are not only available at most time and site, but also good for individualization, visual understanding and interest. Face-to-face lecture provided student a chance to integrate with knowledge and experience and had desire to improve good lifestyle and health promotion. Conclusions: The blended learning method on good lifestyle and health could make a best use of improvement for knowledge, attitude and behavior concerning. It is needed to identify the long term effects of a blended learning for further study.

• 한국실천공학교육학회논문지
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• 제2권1호
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• pp.52-57
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• 2010

온라인 강의가 제공되는 운영체제 교과목을 활용하여 면대면 강의와 온라인 강의를 혼합한 혼합형 학습을 진행하였다. 혼합형 학습의 효율적인 운영방안을 찾기 위하여 01분반은 2시간의 면대면 교육과 1시간 온라인 교육으로 강의를 구성하였고, 다른 02분반은 2시간의 온라인 교육과 1시간의 면대면 교육을 구성하였다. 중간고사 평가 결과 두 집단의 Cohen's d는 0.165로 큰 차이는 없었지만, 면대면 교육 시간이 많았던 01분반의 평균이 온라인 교육 시간이 많았던 02분반의 평균보다 조금 높았으며, 학생들의 점수 분산이 작았다. 반면 고득점자는 02분반이 많았다. 자기 주도형 학습이 용이한 온라인 교육이 많은 분반에서 더 많았다. 자기 주도 학습을 잘 수행할 수 있는 상위권 학생은 온라인 교육이 강조된 혼합형 학습이 적합하고, 그렇지 않은 학생들은 면대면 중심의 학습이 적합한 것을 알 수 있었다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1999년도 학회창립 10주년 기념 1999년도 가을 학술발표회 논문집
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• pp.341-344
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• 1999

In the case of the offshore concrete structures like the anchorage block of a suspension bridge of Kwangan Grand Road, there is a need of the concrete which has low heat of hydration and good resistance for sea-water attack. In this study, the blended super low heat cement which satisfies that requirement was developed and several tests were carried out. The concrete using the blended super low heat cement showed lower adiabatic temperature rise than 3$0^{\circ}C$ and good early strength. Also, its passed charge(coulomb) to resist chloride ion penetration was very low.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1998년도 가을 학술발표회 논문집(I)
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• pp.19-24
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• 1998

In this study, blended cement with low blaine(2000, 3000$\textrm{cm}^2$/g) blast-furnace slag power by 10-70wt.% was investigated through the measurement hydration heat, physical properties. The experiment results indicated compressive strength was decreased as low blaine slag blended, but hydration heat was reduced significantly and flow of the cement paste was increased.

• 디지털융복합연구
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• 제11권10호
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• pp.719-730
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• 2013

S 대학교 교양필수 과목인 영어회화는 영어교육을 강화하기 위해 블렌디드 학습으로 설계되었다. 이 블렌디드 학습이 학습자의 학업성취도에 어떤 영향을 미치는지 알아보기 위해 학업성취도의 변인에 대한 연구가 진행되었다. 연구결과로 성별, 전공, 군복무, 해외거주 경험, 면대면 출석, 퀴즈, 온라인 출석이 학업성취도에 영향을 미치고 온라인 학습방식(학습장소, 학습시간, 학습빈도)은 학업성취도와 상관이 없는 것으로 나타났다. 온라인 학습만족도는 강사 만족도, 학습내용 만족도, 시스템 만족도로 나누어 조사했는데, 그 결과 단지 시스템 만족도만 학업성취도에 영향을 미친 것으로 나타났다.

• 공학교육연구
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• 제25권5호
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• pp.75-84
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• 2022

In the post-Corona era, blended learning will be one of the most important instructional strategies for successful education. The purpose of this study is to examine reliability and validity of the instrument developed in the instructional aspect so that a successful blended learning can take place. This instrument consists of 31 items to evaluate class operation, online learning environment, online contents, offline class, interaction and overall satisfaction. For this study, a survey was conducted in LMS and the responses of 164 students were used for analysis. Confirmatory factor analysis was used to evaluate validation of this instrument and this analysis was run in R studio. As a result of CFA, the standardized factor loadings of all items were 0.930~0.754 and the reliability and validity of all constructs were adequate. The results of this instrument enable universities to manage the quality of their classes and instructors can use them as self-checklist to improve future classes in terms of instructional points. Finally, this instrument can be used in a variety of learner-centered learning environments.

• 한국가스학회지
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• 제14권1호
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• pp.8-14
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• 2010

본 연구에서는 LPG/바이오디젤 혼합연료의 직접분사식 디젤엔진 적용성에 관한 실험을 수행하였다. 특히, 혼합연료를 엔진에 적용하는 경우 엔진성능, 배출가스 (미연탄화수소, 일산화탄소, 질소산화물, 이산화탄소), 연소안정성에 대한 실험을 1,500 rpm의 엔진회전수 조건에서 수행하였다. 바이오디젤은 질량대비 20-60% 범위로 LPG에 혼합하였다. 바이오디젤을 40% 이상 혼합하는 경우 엔진은 모든 부하영역에서 매우 안정적으로 연소되었다. 바이오디젤의 혼합율이 증가할수록 혼합연료의 세탄가가 향상되어 연소시작 시점이 진각되었다. 혼합연료를 사용하면 저부하에서는 과혼합에 의한 부분연소로 인하여 THC와 CO의 배출량이 급증하였으며, NOx의 경우 저부하에서는 배출량이 디젤연료에 비해서 낮았으며 고부하에서는 더 많이 배출되었다.

• 한국건설순환자원학회논문집
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• 제8권1호
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• pp.39-48
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• 2020

본 연구에서는 철과 니켈의 합금강 제조공정에서 발생하는 산업부산물인 페로니켈슬래그를 혼입하여 기존 결합재와의 화학반응 및 성능을 확인하였다. 고로슬래그 미분말과 페로니켈슬래그를 활용하여 시멘트 대비 치환률 50%까지 삼성분계 치환하여 실험을 통해 기초 물성 및 특징을 평가하였다. 실험 결과에 따르면 페로니켈슬래그를 혼입할 시 포졸란 반응이 기여하여 밀실한 내부 공극 및 수화물이 형성되었고, 수화열과 건조 수축 감소 효과도 나타났다. 압축강도는 초기 재령에는 다소 저조한 강도발현을 나타냈으나, 28일 장기재령으로 갈수록 강도 증가가 나타났다. 추후 최적 배합을 도출하여 용도에 맞게 활용할 경우 시멘트 결합재로서의 활용 가능성이 기대된다.

• 한국자동차공학회논문집
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• 제18권5호
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• pp.76-84
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• 2010

The aim of this study is to analyze the effect of the ethanol blending in diesel-ethanol blended fuels on the spray and combustion characteristics in a common-rail four-cylinder diesel engine. For the analysis of the spray characteristics, the spray images were obtained using a high speed camera with metal-halide lamps. From these spray images, the macroscopic spray characteristics such as the spray tip penetration and spray cone angle were investigated. Also, the combustion characteristics including the combustion pressure and the rate of heat release were studied with the analysis of the exhaust emissions in diesel-ethanol blended fuel driven diesel engine. It can be confirmed from the experiment on spray characteristics of diesel-ethanol blended fuels that the increased ethanol blending ratio induced the decrease of the spray tip penetration after the end of the injection. The spray cone angle slightly increased by the blending of ethanol fuel. In the experiment on atomization characteristics, the ethanol blending caused the improvement of the diesel atomization performance. On the other hand, at the same engine load condition, the increase of the ethanol blending ratio lead to lengthen the ignition delays, and to decrease the peak combustion pressure and the rate of heat release. Totally, the combustion and emission characteristics of ULSD and DE10 showed similar characteristics. However, in the case of DE20, CO and HC rapidly increased, and $NO_x$ decreased. It can be believed that 20% ethanol disturbed the combustion of diesel-ethanol blended fuel due to the low cetane number and evaporation.

• 한국자동차공학회논문집
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• 제18권3호
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• pp.80-87
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• 2010

The purpose of this paper is to analyze the effects of ethanol blending ratio and fuel temperature in diesel-ethanol blended fuel on the spray-atomization characteristics in a high pressure common-rail injection system. In this work, a diesel fuel and three blended fuels were used as test fuels. Blended fuels were made by blending ethanol with a purity 99.9% to diesel fuel, from 0% to 30%. In order to keep diesel-ethanol blending stability, 5% of biodiesel fuel as volumetric ratio was added into test fuels. The fuel temperature was controled in steps with 40K, from 290K to 370K. Macroscopic spray characteristics were investigated by analyzing the spray tip penetration and spray cone angle through spray images obtained from visualization system. In addition, in order to study microscopic spray characteristics of ethanol blended fuels, the droplet diameter, was analyzed using the droplet measuring system. It is revealed that the spray tip penetration is similar regardless of ethanol blending ratio. As ethanol blending ratio is increased, the spray cone angle becomes wider. It is shown that the spray cone angle is affected by low viscosity and density of ethanol. As the fuel temperature increases, the spray tip penetration and spray cone angle become shorter and narrower respectively. The SMD of ethanol blending fuels is smaller than that of diesel fuel because of low viscosity and surface tension of ethanol.