• 제목/요약/키워드: charge transport

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Improved Performance in Polymer/Polymer Solar Cells

  • Kim, Young-Kyoo
    • 한국정보디스플레이학회:학술대회논문집
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    • 한국정보디스플레이학회 2009년도 9th International Meeting on Information Display
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    • pp.1129-1129
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    • 2009
  • Here the improved performance of polymer/polymer solar cells, which are of importance to achieve real plastic solar cells in the near future, is reported. First, the progress in polymer/polymer solar cells is briefly reviewed and then the limiting factors are discussed in terms of charge transport.

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충전율의 변화가 밀폐형 2-상 열사이폰의 열전달 특성에 미치는 영향에 관한 연구 (The Effect of the Fill Charge Ratio on the Heat Transfer Characteristics of a Two-Phase Closed Thermosyphon)

  • 박용주;홍성은;김철주
    • 대한기계학회논문집B
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    • 제26권12호
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    • pp.1646-1654
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    • 2002
  • A two-phase closed thermosyphon was one of the most effective devices in the removing heat because of its simple structure, thermal diode characteristics, wide operating temperature range and so on. In this study, a two-phase closed thermosyphon(working fluid PFC(C6F14), container copper(inner grooved surface)) was fabricated with a reservoir which can change the fill charge ratio. The experiments were performed in the range of 50~600W heat flow rate and 10~70% fill charge ratio. The results were compared with some correlations that were presented by Rohsenow and Immura et al. in the evaporator, by Nusselt, Gross and Uehara et al. in the condenser and by Cohen and Bayley, Wallis, Kutateladze and Faghri et al. in heat transfer limitation etc.. The heat transfer coefficient at the evaporator increased with the input power. However the effect of the fill charge ratio was nearly negligible. At the condenser, it showed an opposite trend to the evaporator and with increase of the fill charge ratio, showed some enhancement of heat transfer. The heat transport limitation was occurred by the dry-out limitation for small fill charge ratio(10%) and presented about 100W. For the case of large fill charge ratio(Ψ$\geq$40%), it was occurred by the flooding limitation at about 500W.

리튬이온 전지의 충방전 특성에 대한 전산 모델링 (Computational Modeling of Charge-Discharge Characteristics of Lithium-Ion Batteries)

  • 이대현;윤도영
    • 에너지공학
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    • 제20권4호
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    • pp.278-285
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    • 2011
  • 본 연구에서는 리튬이온 전지의 충 방전 특성에 관한 모델링과 전산모사를 수행하였다. 전지의 시스템 구성은 단순화된 2차원 형태의 단일셀에 대하여 모델링하였고, 공학적 편미분방정식 풀이자인 FEMLAB을 이용하여 288 K와 318 K 범위내에서 충방전 특성에 대한 열적 모델링을 수행하였다. 모델링에 채택한 물성치 변수들에 대하여 온도특성을 고려하였으며, 이를 통하여 전지의 특징적인 충방전의 사이클 변화와 충방전 전하량의 변화를 체계적으로 전산모사하였다. 그 결과 충방전 속도에 상관없이 충방전의 주기가 온도가 낮아질수록 짧아짐을 정량적으로 해석할 수 있었다. 이에 부가하여 전지내에서 리튬이온의 물질전달 현상을 해석하여, 전지의 충방전 특성과의 상관관계를 고찰하였다.

일부지역 119 구급대와 사설이송기관의 이송 서비스 이용 실태와 만족도에 관한 연구 (A Study on the Use Realities and Satisfaction with Transport Services in 119 Emergency Medical Service System and Private Transport Agent in Some Areas)

  • 박상섭;박재성
    • 한국응급구조학회지
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    • 제12권1호
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    • pp.5-15
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    • 2008
  • Purpose : Centering on users(patients) who are offered the patient transport service by the emergency medical service system in our country, the use and satisfaction are analyzed with the transport service in 119 Emergency Medical Service System and Private transport agent. Results : 1. As for personnel in ambulance cars, 119 emergency staff showed a higher boarding rate of the first-class emergency medical technicians than private transportation centers : 48.4% and 17.7%, respectively. 2. Private transportation centers showed higher user satisfaction with transportation service than 119 emergency staff, which was not statistically significant. 3. As for the case that needs to receive the transport service in the future, the ratio with the will to use 119 Emergency Medical Service System(70.9%) was indicated to be much higher than the ratio of the private transport agent(29.1%). Suggestions : First, Centers transporting first-aid patients should essentially secure a sufficient number of first-class emergency medical technicians as professional emergency medical staff to reinforce qualitative improvement in emergency medical service. Second, It is necessary to establish a systematic monitoring system and develop educational programs in order to enhance satisfaction with the use of 119 emergency staff. Third, the government or the local government needs to positively support and guide the private transport agent, which is in charge of the public medical service.

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지속가능 물류를 위한 TP-SD 방법론 기반의 복합운송체계 시뮬레이션 모델 개발 (Development of TP-SD Methodology-based Simulation Models to Improve Multimodal Transport Systems for Sustainable Logistics)

  • 정재운;김현수;최형림;홍순구
    • 한국시스템다이내믹스연구
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    • 제11권2호
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    • pp.45-75
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    • 2010
  • Today, the logistics industry has played a critical role in national economy activities. The low cost and high efficiency of the logistics industry are meaningful in the improvement of national competitiveness and the logistics industry. However, efficiency of logistics is lower than that of the United States and Japan since most quantities are processed in road transportation in Korea. With regard to this, existing studies expected a saving of social and environmental costs due to a decrease of road transportation as well as improvement of logistics productivity due to bulk transportation through activation of rail and costal transport. For the expectation, the existing multimodal transport systems should be improved first. Therefore it aimed to develop scenario-based simulation models of multimodal transport systems for decision makers in charge of improvement in the logistics area. For model development, this study utilized Thinking Process and System Dynamics(TP-SD) methodology.

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Transport properties of boron/nitrogen/phosphorus binary doped graphene nanoribbons: An ab initio study

  • Kim, Seong Sik;Kim, Han Seul
    • EDISON SW 활용 경진대회 논문집
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    • 제2회(2013년)
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    • pp.273-277
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    • 2013
  • We apply a density functional theory (DFT) and DFT-based non-equilibrium Green's function approach to study the electronic and transport properties of graphene nanoribbons (GNRs) co-doped with boron-nitrogen, nitrogen-phosphorus and boron-phosphorus. We analyze the structures and charge transport properties of co-doped GNRs and particularly focus on the novel effects that are absent for the single N-, B-, or P-doped GNRs. It is found that co-doped GNRs tend to be doped at the edges and the electronic structures of co-doped GNRs are very sensitive to the doping sites. Also, in case of B-N and B-P co-doped GNRs, conductance dips of single-doped GNRs disappeared with the disappearance of localized states associated with doped atoms. This may lead to a possible method of band engineering of GNRs and benefit the design of graphene electronic devices.

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세로 검은 줄무늬가 없는 전하 결합 소자의 설계 (Design of a Charge-Coupled Device without Vertical Black Stripes)

  • 박용;이영희
    • 한국정보처리학회논문지
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    • 제4권4호
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    • pp.1100-1105
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    • 1997
  • 세로 검은 줄무늬 전하 결합 소자 결점의 하나이다. 세로 검은 줄무늬는 수직 전하 전송부에서 수평 전하 전송부로 넘어가지 못하는 신호 전하량에 의하여 나타난 것이다. 신호 전하의 불완전한 전송은 수직-수평 채널 경계 영역 구조에서 좁은 폭 효과에 의하여 발생한 전위 장벽 때문이다. 세로 검은 줄무늬는 저 조도하에서 전하 전송 효율이 99.2% 이하로 전송될 때 나타난다. 본 논문은 새로운 수직-수평 채널 경계 영역 구조를 전위 장벽이 발생하지 않도록 부채꼴 형태로 설계 제작하여 세로 검은 줄무늬를 제거하였다.

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