• Title/Summary/Keyword: Device Efficiency

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Memory Usage Based Device Frequency Adjustment for an Embedded Linux System (임베디드 리눅스 환경에서 메모리 사용량에 근거한 에너지 효율적 디바이스 주파수 변경 기법)

  • Jang, Jaehyeon;Park, Moonju
    • KIISE Transactions on Computing Practices
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    • v.22 no.10
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    • pp.513-520
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    • 2016
  • As IoT devices become more common in the public sphere, the energy efficiency of embedded systems becomes a problem of major interest in addition to the system performance. Energy efficiency is important for portable embedded systems because they obtain power from their battery, and a low energy efficiency will result in a low usage time while a high energy efficiency will allow for longer usage time. In this paper, we propose a memory usage based frequency selection method to improve the energy efficiency of embedded Linux systems by using devfreq to select the device's system frequency. In our experiments, we found that the proposed method reduces energy consumption in an embedded device by up to 18%.

Improving electroluminescent efficiency of organic light emitting diodes by co-doping (Co-doping을 이용한 OLED의 발광 효율 향상)

  • Park, Young-Wook;Kim, Young-Min;Choi, Jin-Hwan;Ju, Byeong-Kwon
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2006.04a
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    • pp.81-82
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    • 2006
  • Doping is a well-known method for improving electroluminescent (EL) efficiency of organic light emitting diodes. In our study, doping with 2 materials simultaneously, we could achieve improved EL efficiency. The emission layer was tris-(8-hydroxyquinoline)aluminum, and the 2 dopants were N,N'-dimethyl-quinacridone (DMQA) and 10-(2-Benzothiazolyl)-2, 3, 6, 7-tetrahydro-1,1,7,7,-tetramethyl 1-1H, 5H, 11H-[1] benzopyrano [6,7,8-ij]quinolizin-11-one (C-545T). The EL intensity of co-doped device was nearly flat, it shows that co-doping technique could be a effective way to improve the EL efficiency. EL efficiency of Single-doped device based on DMQA and C-S45T were ~6.47Cd/A and ~7.45Cd/A, respectively. Co-doped device showed higher EL efficiency of ~8.30Cd/A.

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High Efficiency and Long Lifetime for Organic Light-Emitting Diode Using New Electron Transport Materials

  • Tanaka, Tsuyoshi;Sato, Masaru;Aihara, Hidenori;Yanai, Naoko;Yamakawa, Tetsu
    • 한국정보디스플레이학회:학술대회논문집
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    • 2007.08a
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    • pp.625-627
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    • 2007
  • We demonstrated high power efficiency and long lifetime in organic light-emitting diode (OLED) using new electron transport materials (ETMs). Electroluminescent device with these ETMs showed lower driving voltage than that with $Alq_3$. The device lifetime with a new ETM was 2 times longer than that with $Alq_3$.

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CFD Analysis of the Inertial Impaction Pre-Filter for a Particulate Matter Collecting Device (미세먼지 포집장치 개발을 위한 관성충돌 프리필터 유동 전산해석)

  • Kyung, Dae Seung;Hwang, Dae Sung
    • Land and Housing Review
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    • v.10 no.2
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    • pp.53-58
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    • 2019
  • Particulate matter (PM) is designated as a group 1 carcinogen by the International Agency for Research on Cancer (IARC) of the World Health Organization (WHO). In South Korea, the health threat caused by PM is the most serious level internationally. Therefore, in order to solve the urban PM problem, it is important to develop the technology that can control PM efficiently. In this study, CFD(Computational Fluid Dynamics) simulation was performed for PM pre-filter (type 1-3 with different PM collecting room) to develop a high-efficiency PM collecting device. The complex flow field and the local flow phenomenon inside the PM collecting device were understood with CFD simulation by changing the shape and size of the pre-filter. The PM removal performance can be described with flow rate through the device and PM removal efficiency. The type-1 pre-filter with 5x5 size collecting room was confirmed to have the highest efficiency. Based on the analysis results, the optimal type of pre-filter could be developed and it would be applied as an element technology included in the PM collecting device.

A Study on the Efficiency Effects of Capping Layer on the Top Emission Organic Light Emitting Diode (전면 유기발광 다이오드 기능층 캐핑레이어 적용에 따른 효율상승에 관한 연구)

  • Lee, DongWoon;Cho, Eou Sik;Jeon, Yongmin;Kwon, Sang Jik
    • Journal of the Semiconductor & Display Technology
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    • v.21 no.3
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    • pp.119-124
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    • 2022
  • Top emission organic light-emitting diode (TEOLED) is commonly used because of high efficiency and good color purity than bottom - emission organic light-emitting device (BEOLED). Unlike BEOLED, TEOLED contain semitransparent metal cathode and capping layer. Because there are many characteristics to consider just simple thickness change, optimizing organic thickness of TEOLED for microcavity is difficult. So, in this study, we optimized Device capping layer at unoptimized micro-cavity structure TEOLED device. And we compare only capping layer with unoptimized microcavity structure can overcome optimized micro-cavity structure device. We used previous our optimized micro-cavity structure to compare each other. As a result, it has been found that the efficiency can be obtained almost the same or higher only capping layer, which is stacked on top of the device and controls only the thickness and refractive index, without complicated structural calculations. This means that higher efficiencies can be obtained more easily in laboratories with limited organic materials or when optimizing new structures etc.

Emission Property of Organic EL Device using Polyaniline Transparent Electrode (Polyaniline 투명전극을 사용한 유기EL 소자의 발광 특성)

  • Kim, Ju-Seung;Kim, Dae-Jung;Gu, Hal-Bon
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2001.11b
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    • pp.374-377
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    • 2001
  • We have synthesized poly(3-hexylthiophene)(P3HT), which is the most famous conducting polymer and studied the optical properties of P3HT. And then fabricated the device using P3HT as an emitting layer. For the improve of hole injection from ITO electrode to P3HT emitting layer, we use transparent polyaniline(PANI) electrode. In the voltage-current-luminance characteristics of ITO/PANI/P3HT/LiF/Al device which use the PANI film synthesised during 5 cycle, the device turn on at the 2V and the luminance of $218nW/cm^{2}$ obtained at 12V. External quantum efficiency of ITO/PANI/P3HT/LiF/Al increased at 8V than that of ITO/P3HT/LiF/Al device.

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Emission Property of Organic EL Device using Polyaniline Transparent Electrode (Polyaniline 투명전극을 사용한 유기EL 소자의 발광 특성)

  • 김주승;김대중;구할본
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2001.11a
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    • pp.374-377
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    • 2001
  • We have synthesized poly(3-hexylthiophene)(P3HT), which is the most famous conducting polymer and studied the optical properties of P3HT. And then fabricated the device using P3HT as an emitting layer. For the improve of hole injection from ITO electrode to P3HT emitting layer, we use transparent polyaniline(PANI) electrode. In the voltage-current-luminance characteristics of ITO/PANI/P3HT/LiF/Al device which use the PANI film synthesised during 5 cycle, the device turn on at the 2V and the luminance of 218 nW/$\textrm{cm}^2$ obtained at 12V. External quantum efficiency of ITO/PANI/P3HT/LiF/Al increased at 8V than that of ITO/P3HT/LiF/Al device.

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Thermal Analysis for High Efficiency of Point Contact Solar Cell (후면전극형 태양전지의 열해석에 관한 연구)

  • Nam, Tae-Jin;Kang, Ey-Goo
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.24 no.5
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    • pp.351-354
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    • 2011
  • This paper was carried about thermal analysis for high efficiency point contact solar cell. Therefore, we carried about 2-D device and process simulator according to design and process parameters. As a result of simulations, power transfer efficiency have decreased more increasing temperature. Especially, power transfer efficiency of room temperature have been showed 25%. The other hand, power transfer efficiency of 350 K kalvin temperature have been showed 20%. Therefore, we will considered design with thermal dissipation of device.

Self-developed Efficiency Measurement System of Organic Light-Emitting Diodes (자체 개발한 유기 발광 소자의 효율 측정 시스템)

  • Han, Wone-Keun
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2005.07a
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    • pp.537-538
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    • 2005
  • A way of measuring an efficiency of organic light-emitting diodes are studied. The efficiency is obtained from the current-voltage-luminance characteristics of the devices. Basically, number of charge carriers are obtained from the current-voltage characteristics, and the number of photons are obtained from the current of Si-photodetector. The organic light-emitting diodes are assumed as a lambertian light source and a program is made for calculating the efficiency. A device structure of ITO/TPD/$Alq_3$/Al is manufactured using thermal-vapor evaporation. This device is set into a measuring system and measured the efficiency. The efficiencies are measured using the lab-made program and commercially available equipments. The obtained values are similar to each other within 10% uncertainty.

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A Data Transmission Mode Change Method for Improving Energy Efficiency in IoT Environments

  • Lee, Sukhoon;Kim, Kwangsu;Jeong, Dongwon
    • Journal of Advanced Information Technology and Convergence
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    • v.10 no.1
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    • pp.57-69
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    • 2020
  • In general, many IoT devices, including smart phones, use LTE, Wi-Fi, and Bluetooth, and these communication modules generate a lot of energy consumption during periodic data transmission. This paper proposes a method of the data transmission mode change for improving energy efficiency in various communication environments that mobile devices may encounter. We propose an algorithm for setting the mode considering energy efficiency, data transmission performance and cost when the mobile device transmits data, and transmitting the data in an optimized manner according to the state of the mobile device. The proposed algorithm is implemented through experiments on energy efficiency for each communication module, and the scenario is used to verify how efficiently the proposed algorithm uses energy.