• Industrial Engineering and Management Systems
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• 제12권4호
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• pp.351-358
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• 2013

This paper proposes a multiobjective model describing the trade-offs involved in selecting the locations of drop-off boxes for collecting used products and transporting these products to designated locations. We assume the following reverse flow of used products. Owners of used products (cellular phones, digital cameras, ink cartridges, etc.) take them to the nearest drop-off box when the distance is reasonably short. We also assume that owners living closer to drop-off boxes dispose of more used products than do owners living farther from drop-off boxes. Different types of used products are collected, with each type requiring its own drop-off box. A transportation destination for each product is specified. Three objectives are considered: maximizing the volume of used products collected at drop-off boxes; minimizing the cost of transporting collected products to designated locations; and minimizing the cost of allocating space for drop-off boxes. We formulate the above model as a multiobjective integer programming problem and generate the corresponding set of Pareto optimal solutions. We apply the model to an area using population data for Chofu City, Tokyo, Japan, and analyze the trade-offs between the objectives.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2010년도 추계학술대회 초록집
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• pp.51.2-51.2
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• 2010

In recently, interests in the New & Renewable Energy are increasing because of exhaustion of fossil energy and limit of greenhouse gas emission all over the world. Furthermore, improvements in living standards and high-raise Buildings due to the industrial growth require a lot of sunlight in the interior space. Sunlight system gets the natural light into the indoor dark space. There are a lot of type of systems which are reflector type, duct type, optical fibers type and so on. And these systems consist of light-collection module, light-transporting module and light-emitting module. In this research, we installed optical fiber sunlight system in our head office building and tested the system's performance and efficiency. Optical fiber sunlight system is closely connected with hour of sunlight, due to the system have to chase the sun for the solar concentrating, and the system's light-collection and light- transporting efficiency is important factors in the system's performance. As a result of the test, system can be used about 5.66 hours on average in a day, and it has a about 3.21 times collection efficiency and 5.5% transmission loss.

• Journal of Forest and Environmental Science
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• 제29권1호
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• pp.81-89
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• 2013

Nowadays, excessive using of fossil fuel contributes to global warming. Also, this phenomenon increases steadily. Therefore forest biomass from logging residues has received attention. The goal of this study was to determine the sustainability and economic feasibility of forest-biomass energy source. Accordingly, forest biomass resource was calculated, and harvesting and transporting machines which can be used in investing area were chosen, when using forest biomass as energy source. And then through these data, the harvesting cost was decided. The forest biomass resource calculated, thinned trees and logging residues, was 37,330.23 $m^3$ and 14,073.60 ton, respectively. When harvesting timber in each sub-compartment, the average thinned trees yield was 120.73 $m^3$, and tree logging residues was 402.80 ton. The use of tower yarder as harvesting and transporting equipments in study area was 85.4% and 66.7%, respectively, in up hill and down hill yarding. The average harvesting cost of biomass in the possibility area of timber yarding operation was expensive as 81,757 won/$m^3$, 85,434 won/m3 and 50,003 won/ton, respectively, in thinned trees and logging residue. If using data from this research analysis, tree could be felled by choosing sub-compartment.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2015년도 제49회 하계 정기학술대회 초록집
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• pp.150.2-150.2
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• 2015

In this study, we analyzed the electric and optical characteristics by using various deposition rate ($0.5{\AA}$, $1.0{\AA}$ and $1.5{\AA}/s$) in order to enhance the performance in organic light-emitting devices (OLED). The organic multi-layer structures were deposited with NPB ($500{\AA}$ as hole transport layer), Alq3 ($600{\AA}$ as electron transport layer and emission layer) and LiF ($8{\AA}$ as electron injection layer) via SUNIC PLUS200 on Glass/ITO substrates. In this experiment, we examined the relationship between porous state of organic deposition and mobility of the organic materials. Among the three deposition rates, $0.5{\AA}/s$ achieved the highest performance of (10,786cd/m2, 4.387cd/A) comparing with that of $1{\AA}/s$ (7,779cd/m2, 3.281cd/A) and $1.5{\AA}/s$ (5,167cd/m2, 2.693cd/A). We confirmed that low deposition rate helps to arrange organic materials densely and to move easily another atomic location using inter-chain transporting by orbital overlap.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2008년도 International Meeting on Information Display
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• pp.549-552
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• 2008

We have developed a novel bipolar host material with both electron and hole transporting characteristics. Since CGH(Cheil Green Host) has some electron transporting characteristics, it shows increased luminance efficiency in device including TCTA and without HBL(hole blocking layer:BAlq). Maximum power efficency of CGH was 27.4lm/W at the device structure ITO/DNTPD(60)/NPB(20)/TCTA(10)/EML(30)/Alq3(20)/LIF(1)/Al. We measured device performance again without HBL. The result of CGH showing 26.0lm/W is outstanding compared to that of CBP showing 19.1lm/W without holeblocking layer. We also measured lifetime and found to be 205hr at 3000nit, that is significant result compared to the life time of CBP device showing 82hr. CGH shows high device performance with holeblocking layer. Moreover, it shows better device performance and life time than those of CBP without holeblocking.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2006년도 6th International Meeting on Information Display
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• pp.956-960
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• 2006

Deep-blue organic light-emitting diodes (OLEDs) with/without ultra-thin LiF layer inserted at the interface between hole-blocking and electron-transporting layers have been fabricated and investigated. The fundamental structures of the OLEDs are ITO/m-MTDATA/NPB/BCP/LiF (with/ without)/ $Alq_3/LiF/Al.Deep$ blue light emission with CIE coordinate of (0.15, 0.11) has been achieved for all devices. Further, by inserting LiF with thickness of 1nm at the interface between BCP and $Alq_3$ layer, the luminous efficiency as well as the power efficiency is much improved compared to that without. The enhancement of electron injection due to insertion of LiF may account for this improvement.

• 한국전기전자재료학회논문지
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• 제18권7호
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• pp.641-646
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• 2005

To fabricate a single layer white organic light emitting diode (OLED), a novel non-conjugated blue emitting material PPPMA-co-DTPM copolymer was synthesized containing a perylene moiety unit with hole transporting and blue emitting ability and a triazine moiety unit with electron transporting ability. The devices were fabricated using PPPMA-co-DTPM $(PPPMA[70\;wt\%]:DTPM[30\;wt\%])$ copolymer by varying the doping concentrations of each red, green and blue fluorescent dye, by molecular-dispersing into Toluene solvent with spin coating method. In case of ITO/PPPMA-co-DTPM:TPB$(3\;mol\%):C6(0.04\;mol\%):NR(0.015\;mol\%)/Al$ structure, as they were molecular-dispersing into 30 mg/ml Toluene solvent, nearly-pure white light was obtained both (0.325, 0.339) in the CIE coordinates at 18 V and (0.335, 0.345) at 15 V. The turn-on voltage was 3 V, the light-emitting turn-on voltage was 4 V, and the maximum external quantum efficiency was $0.667\%$ at 24.5 V. Also, in case of using 40 mg/ml Toluene solvent, the CIE coordinate was (0.345, 0.342) at 20 V.

• 한국가스학회지
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• 제6권4호
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• pp.53-58
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• 2002

본 연구에서는 지금까지의 고정설비에 대한 정량적 위험성 평가에서 벗어나 위험물질 수송 시 고려되는 여러 가지 요소들을 확인하여 발생할 수 있는 잠재위험성을 확인하였다. 수송 시 발생할 수 있는 잠재위험성을 확인하였다. 또한 수송 시 발생할 수 있는 최악의 사고 시나리오와 대안적인 사고 시나리오를 통하여 피해 영향 범위에 대한 개인적 위험성 및 사회적 위험성을 평가하였으며 최적의 경로를 선정하였다. 이러한 평가를 기반으로 수송 시 중대사고의 피해 영향 범위에 대한 효율적인 위험성 감소 대책과 지역사회, 공공기관, 산업체들과의 연계를 통한 사고에 따른 피해를 최소화 할 수 있는 체계적인 비상대응 시스템을 구축할 수 있을 것이다.

• ETRI Journal
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• 제38권2호
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• pp.260-264
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• 2016

We report on highly efficient blue, orange, and white phosphorescent organic light-emitting diodes consisting only two organic layers. Hole transporting 4, 4,' 4"-tris (N-carbazolyl)triphenylamine (TcTa) and electron transporting 2-(diphenylphosphoryl) spirofluorene (SPPO1) are used as an emitting host for orange light-emitting bis(3-benzothiazol-2-yl-9-ethyl-9H-carbazolato) (acetoacetonate) iridium ((btc)2(acac)Ir) and blue light-emitting iridium(III)bis(4,6-difluorophenyl-pyridinato-N,C2') picolinate (FIrpic) dopant, respectively. Combining these two orange and blue light-emitting layers, we successfully demonstrate highly efficient white PHOLEDs while maintaining Commission internationale de l'eclairage coordinates of (x = 0.373, y = 0.443). Accordingly, we achieve a maximum external quantum, current, and power efficiencies of 12.9%, 30.3 cd/A, and 30.0 lm/W without out-coupling enhancement.

• ETRI Journal
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• 제34권5호
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• pp.690-695
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• 2012

We investigate the light-emitting performances of blue phosphorescent organic light-emitting diodes (PHOLEDs) with three different electron injection and transport materials, that is, bathocuproine(2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline) (Bphen), 1,3,5-tri(m-pyrid-3-yl-phenyl)benzene (Tm3PyPB), and 2,6-bis(3-(carbazol-9-yl)phenyl)pyridine (26DCzPPy), which are partially doped with cesium metal. We find that the device characteristics are very dependent on the nature of the introduced electron injection layer (EIL) and electron transporting layer (ETL). When the appropriate EIL and ETL are combined, the peak external quantum efficiency and peak power efficiency improve up to 20.7% and 45.6 lm/W, respectively. Moreover, this blue PHOLED even maintains high external quantum efficiency of 19.6% and 16.9% at a luminance of $1,000cd/m^2$ and $10,000cd/m^2$, respectively.