• Journal of Biosystems Engineering
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• 제31권2호
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• pp.115-120
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• 2006

Our environment is faced with serious problems related to the air pollution from diesel engines in these days. In particular, the exhaust emissions of agricultural diesel engines are recognized main cause which influenced environment strongly. In this study, the potential possibility of biodiesel fuel was investigated as an alternative fuel for a naturally aspirated agricultural D.I. diesel engine. The smoke emission of biodiesel fuel was reduced remarkably in comparison with diesel fuel, that is, it was reduced approximately 50% at 2500 rpm, full load. But, power, torque and brake specific energy consumption didn't have large differences. But, NOx emission of biodiesel fuel was increased compared with commercial diesel fuel. Also, the effects of exhaust gas recirculation (EGR) on the characteristics of NOx emission has been investigated. It was found that simultaneous reduction of smoke and NOx was achieved with biodiesel fuel (20vol-%) and cooled EGR method($5{\sim}15%$) in an agricultural D.I. diesel engine.

• JSTS:Journal of Semiconductor Technology and Science
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• 제8권1호
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• pp.98-103
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• 2008

1T1C DRAM has been facing technological and physical constraints that make more difficult their further scaling. Thus there are much industrial interests for alternative technologies that exploit new devices and concepts to go beyond the 1T1C DRAM technology, to allow better scaling, and to enlarge the memory performance. The technologies of DRAM cell are changing from 1T1C cell type to capacitor-less 1T-gain cell type for more scalable cell size. But floating body cell (FBC) of 1T-gain DRAM has weak retention properties than 1T1C DRAM. FET-type 1T-FeRAM is not adequate for long term nonvolatile applications, but could be a good alternative for the short term retention applications of DRAM. The proposed nonvolatile refresh scheme is based on utilizing the short nonvolatile retention properties of 1T-FeRAM in both after power-off and power-on operation condition.

• 재활복지공학회논문지
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• 제6권1호
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• pp.37-43
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• 2012

본 논문은 안드로이드기반 모바일 보완대체의사소통시스템(AAC)의 기능 및 사용자인터페이스(UI)에 대한 사용성 평가에 대한 것이다. 시나리오를 사용한 평가를 통해 특정 기능실행의 용이성, 기능사용의 만족도, 정보찾기의 용이성 등을 살펴보았고, 설문조사를 통해 모바일 AAC의 개발목적, 내용, 교수학습 전략, 활용가능성, 편집/설정 기능과 사용자인터페이스 등이 무발화아동의 의사소통 요구에 적합한지를 평가하였으며, 자유 피드백을 통하여 사용자의 선호도, 만족도, 요구분석 사항 등에 대한 피드백들을 조사하고 분석하였다. 또한 5인치, 7인치, 4.3인치의 모바일 기기를 사용하여 다양한 크기의 안드로이드기반 모바일 기기에 대한 사용자의 선호도를 조사하였다.

• Journal of Animal Science and Technology
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• 제45권5호
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• pp.725-730
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• 2003

This study was conducted to evaluate the adequacy of an alternative a.m.-p.m. testing scheme for milk yield in comparison with the official test method based on weighing two milkings within 24 h. A total of 8,309 p.m. milking weights and 6,767 a.m. milking weights from 72 Holstein cows raised at N.L.R.I. were collected between October 2000 and November 2001. Ratios were computes for daily milk yield to a.m. and p.m. milking weights(direct yield ratios) and ratios of a.m. and p.m. milking weights to daily milk yield (inverse yield ratios). Analysis of variance indicated that the milking interval is the most important source of variation for yield ratios. Adjustment factors for estimating daily milk yield from single milking weights were derived through regression analysis of direct and inverse yield ratios on the length of the milking interval. Daily milk yield was estimated more precisely and accurately when adjustment factors were used than when single milking weights were doubled. In conclusion, alternative recording of a.m. and p.m. milking weights led to reliable estimates of milk yields.

• 한국수소및신에너지학회논문집
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• 제15권4호
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• pp.324-332
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• 2004

According to the rapid depletion of the fossil fuels, the electricity and hydrogen will gradually take charge of the future energy supply. Especially, in order to control the supply and demand of electricity, energy storage medium is necessary and this could be solved by the combination of water electrolysis and fuel cell. Although electricity can be generated from such alternative energies as hydropower, nuclear, solar, and wind-power resources, alternative energy storage medium is also required since regenerative energies, solar and wind-powers, are intermittent energy resources. In this regard, hydrogen production from water electrolysis was recognized as a superb method for electricity storage. In this work, the current development and economic status of alkaline, solid polymer, and high temperature electrolysis were reviewed, and then the practical use of water electrolysis technology were discussed.

• 청정기술
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• 제14권2호
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• pp.144-151
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• 2008

천연가스로부터 합성가스를 거쳐 제조되는 디메틸에테르가 디젤 대체연료로서 가지는 환경적 가치를 평가하기 위하여 전과정평가를 실시하였다. 전과정평가를 위한 시스템 경계 안에는 디젤과 디메틸에테르 두 물질에 대한 원료 물질의 획득부터 연소를 통한 최종 소비까지의 과정이 포함되었다. 디젤과 디메틸에테르 각각에 대한 목록분석을 실시한 결과 천연자원의 소모와 대기오염물질의 배출이 두 물질과 관련된 가장 중요한 환경오염인자라는 것을 알 수 있었다. 두 물질에 대한 영향평가의 결과로부터 인간의 건강과 생태계 보전이라는 측면에서는 디메틸에테르가 환경적으로 우수하지만 천연자원의 고갈이라는 측면에서는 디젤이 보다 우수함을 알 수 있었다. 목록분석과 영향평가의 결과를 바탕으로 디젤 대체연료로서 디메틸에테르가 가지는 환경적 가치를 제고하기 위한 방안을 제시하였다.

• 한국생산제조학회지
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• 제19권4호
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• pp.521-528
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• 2010

A product system will be improved continually until requirements are satisfied. It is true that considering alternative designs to improve product system is hard work; it is also true that selecting an adequate design idea that represents the needs of stakeholders concerned and meets effectiveness factors properly is not an easy work, either. In the process of driv-ing an idea and designing, which is called Design Phase, there are lots of existing tools for testing the driven idea in DFSS. But, those kinds of tools do not offer the function that helps to select the technically better design idea among alternative design ideas that have the same evaluation level. Moreover it is inappropriate to select adequate alternative design ideas by just verifying only the evaluation table in pugh matrix, since satisfied deviation val-ues are low when there is a too competitive mass product system in a market. Also, for the IT product with short life cycle, faster and more effective testing tool is needed. Therefore, the 'roduct quality index' is suggested in order to select an appropriate candidate design concept for system development that meets requirements by using 'deality concept' pro-vided by TRIZ. According to the result of this research, it is possible to select technically better idea fast and effectively; it is confirmed by applying the approach to the case of LCD BLU (Back Light Unit).

• 정보관리학회지
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• 제39권3호
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• pp.51-67
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• 2022

본 연구는 국내에서 서비스되는 대체자료 장서 수준을 진단하고 향후 대체자료 장서개발의 방향성과 목표지향점을 제시하는 데 목적이 있다. 국가대체자료종합목록과 국내 인기도서 및 신간도서 목록을 장서기반 평가방법을 활용하여 비교·분석하였다. 연구결과 첫째, 10년간 인기도서 목록 기준 대체자료 장서 비율은 90.1%이다. '언어', '예술', '기술과학' 주제의 대체자료 장서 비율이 낮은 편이며, 제작 매체별은 '텍스트 데이지자료'의 비율이 높았다. 둘째, 국가대체자료종합목록을 기준으로 주제별, 매체별, 제작기관별 공통장서 확보율과 장서고유성 지수를 분석한 결과 대체자료의 소장 장서량이 많은 도서관에서 공통장서와 고유장서의 편향성이 높게 나타났다. 공통장서 확보율이 높은 주제는 문학과 사회과학 순이며, 장서고유성 지수가 높은 주제는 종교, 예술, 언어 순으로 나타났다. 셋째, 최근 3년간 신간도서의 대체자료 장서 비율은 5.09%이며 같은 기간 동안 공공도서관의 평균 도서구입율은 8.83%이다. 신간도서 대비 대체자료 장서 비율의 적정 기준은 존재하지 않으며 시각장애인의 정보격차 해소를 위해 신간도서 대비 대체자료 장서 비율을 공공도서관 도서구입율 수준으로 높일 것을 제언하고자 한다.

• 한국응용과학기술학회지
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• 제30권3호
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• pp.528-539
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• 2013

Biodiesel is one of the most important renewable energy, since it is one of the most important alternative and eco-friendly energy source compared to fossil energy, especially for diesel engineequipped vehicles. It is now coming up for preparation of biodiesel as the alternative that applies the hetrogeneous catalyst, super critical state and various methods used in order to reduce the stages of the processes be converted and separation stages started from oil and fat which are originated from animals and wastes, and those new methods bring eco-friendly as well, though some of those are stand on research step so far. It is necessary that nation provides the tax exemption program for the supplier and strengthen the research system for the farming crops relate to fat and oil. It can improve the development of biodiesel which sustains stability against oxidation and keeps good mobility over the low temperatures in the winter season by new additives and develops new processes to show good harmony with diesel engine.

• Nuclear Engineering and Technology
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• 제32권3호
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• pp.274-282
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• 2000

The simulation of water balance was conducted for suggested four alternative multi-layer cover design of near-surface radioactive waste disposal facility under domestic climate condition. The analysis was also conducted for the most favorable one out of four alternative cover design under conservative scenarios. Until 100 years after closure of disposal vault, the infiltration flux for the most favorable cover design was negligible even under doubling of the ambient precipitation condition. When the degradation of asphalt and geomembrane after 100 years of closure was considered, the infiltration flux significantly increased almost to the design criteria of cover system in I' Aube disposal facility. And it was found that the hydraulic conductivity of bentonite/sand as a bottom barrier should be no greater than 1$\times$10$^{-7}$ cm/sec recommended by U.S. EPA.