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Study on the Development of LED Headlamps for Used Cars
정의대,이영림 한국전기전자재료학회 2014 Transactions on Electrical and Electronic Material Vol.15 No.5
Currently, LED headlamps are only attached to newly manufactured vehicles, and it remains difficult to mount LEDheadlamps on used cars. Therefore LED headlamps need to be developed for used cars as a replacement of theirhalogen lamps. Due to a number of spatial limitations, it is critical to ensure a certain level of thermal performance. In order to obtain a design for efficient heat radiation, this paper aimed to optimize thermal management througha combination of heat sinks, heat pipes and fans. Based on such a design, this paper succeeded in developing LEDheadlamps of the desired performance to replace the halogen bulbs of used cars.
정의대,송명훈,남윤석,이보람 한국물리학회 2021 새물리 Vol.71 No.9
Achieving efficient electron transport is challenging owing to the large energy barrier between the conduction band of n-type metal oxide and the lowest unoccupied molecular orbital (LUMO) of the emissive layer in inverted polymer light-emitting diodes (PLEDs) or the active layer in inverted polymer solar cells (PSCs), which results in unbalanced charge transport, leading to low device efficiencies. Herein, we have demonstrated that the device performance could be enhanced in both PLEDs and PSCs by treating either the interface between the electron transport layer (ETL) and the emissive layer in PLEDs or the active layers with self-assembled dipole monolayer (SADM), ionic liquid molecules (ILM) and polar solvent (PS). The interface engineering results in a reduction of the energy barrier, which results in enhanced electron transport in both devices. Especially, optimized PLEDs and PSCs show an external quantum efficiency (EQE) of 1.38% and a power conversion efficiency (PCE) of 4.21%, which are enhanced by approximately 138- and 1.37-fold, respectively, compared to the reference devices. 역구조의 고분자 광전자소자는 산화아연, 산화티타늄 등 n-타입 금속 산화물의 전도대 와 발광소자에서발광층 또는 태양전지에서 광활성층의 최저준위 비점유 분자궤도 사이에 존재하는 큰 에너지 장벽때문에 전자 수송이 원활하게 이뤄지지 않아 불균형적인 전하 수송이 생기며 이는 결과적으로 낮은 소자성능으로 이어진다. 따라서, 본 연구에서는 자기조립 쌍극자 분자, 이온성 액체 분자, 아민 기반의 극성용매를 이용하여 전자수송층과 발광층 또는 광활성층 사이의 계면 조절을 통해 에너지 장벽을 낮춤으로써효과적인 전자 수송을 유도하여 광전자 소자의 성능을 향상시켰다. 특히, 최적화 된 고분자 발광소자에서는기준 소자보다 138배 향상된 1.35%의 외부양자효율을 보여주며, 고분자 태양전지에서는 기준 소자보다1.37배 향상된 4.21%의 광 변환효율을 보여준다.
정의대,문승재,Jeong, Eui-Dae,Moon, Seung-Jae 한국플랜트학회 2010 플랜트 저널 Vol.6 No.2
This study investigated the characteristics of co-combustion of mixed anthracite (domestic and Vietnam) and bituminous coal (Sonoma, Australia) at circulating fluidized bed boiler in Donghae thermal power plant when mixing ratio of bituminous coal is variable. Co-combustion of bituminous coal contributes to improvement in general combustion characteristics such as moderately retaining temperature of furnace and recycle loop, reducing unburned carbon powder, and reducing discharge concentration of NOx and limestone supply owing to improvement in anthracite combustibility as the mixing ratio was increased. However, bed materials were needed to be added externally when the mixing ratio exceeded 40% because of reduction in generating bed materials based on reduction in ash production. When co-combustion was conducted in the section of 40 to 60% in the mixing ratio while the supplied particles of bituminous coal was increased from 6 mm to 10 mm, continuous operation was shown to be possible with upper differential pressure of 100 mmH2O (0.98 kPa) and more without addition of bed materials for the co-combustion of mixed anthracite and bituminous coal (to 50% or less of the ratio) and that of domestic coal and bituminous coal (to 60% of the ratio).
히트싱크 형상 변화에 따른 고출력 LED 안개등 성능 향상에 관한 연구
정의대(Eui Dae Jung),이영림(Young Lim Lee) 한국산학기술학회 2014 한국산학기술학회 학술대회 Vol.- No.-
자동차용 LED 안개등의 경우 협소한 공간으로 인해 방열장치의 사용이 제약된다. 따라서 히트싱크의 방열성능이 LED 정션온도에 가장 많은 영향을 미치게 된다. 본 연구에서는 이러한 히트싱크의 형상을 전산유체 해석을 통해 최적화하여 10W급 LED 안개등을 개발하고자 하였다. 그 결과 방열성능이 매우 우수한 히트싱크를 최적화하는데 성공하였다.