• 제목/요약/키워드: green material

검색결과 1,412건 처리시간 0.028초

CaxSr2-xSiO4:Eu2+ Green-emitting Nano Phosphor for Ultraviolet Light Emitting Diodes

  • Kim, Jong Min;Choi, Hyung Wook
    • Transactions on Electrical and Electronic Materials
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    • 제15권5호
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    • pp.249-252
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    • 2014
  • The aim of this work is to investigate the effect of $Ca_xSr_{2-x}$ and activator on the structural and luminescent properties of green-emitting $Ca_xSr_{2-x}SiO_4:Eu^{2+}$ nano phosphor. Using urea as fuel and ammonium nitrate as oxidizer, $Ca_xSr_{2-x}SiO_4:Eu^{2+}$ has been successfully synthesized, using a combustion method. The particles were found to be small, spherical and of round surface. SEM imagery showed that the phosphors particles are of nanosize. The $Ca_xSr_{2-x}SiO_4:Eu^{2+}$ emission spectrum for 360 nm excitation showed a single band, with a peak at 490 nm, which is a green emission. The highest luminous intensity was at $1,000^{\circ}C$, which was obtained when the $Eu^{2+}$ content (y) was 0.05. The results support the application of $Ca_xSr_{2-x}SiO_4:Eu^{2+}$ phosphor as a fluorescent material for ultraviolet light-emitting diodes (UV-LEDs). Characteristics of the synthesized $Ca_xSr_{2-x}SiO_4:Eu^{2+}$ phosphor were investigated by means of X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), and photoluminescence (PL) detection.

주건공간 관련 친환경 디자인 요소의 중요도와 선호 - 김해지역 아파트 거주자를 대상으로 - (The Importance and Preference of Eco-Friendly Design Elements Related to Residential Space - Focused on the Residents in Gimhae -)

  • 박진경;오찬옥
    • 한국실내디자인학회논문집
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    • 제21권1호
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    • pp.86-94
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    • 2012
  • The purpose of this study was to examine the importance of eco-friendly design elements related to residential space by residents and what element they prefer. To achieve this, 18 eco-friendly design elements related to residential space were selected from the Green Building Certification Criteria and the relevant research papers. These elements were categorized into four areas; the ecological environment area (4 elements), the indoor environmental climate one (4 elements), the energy and resource saving one (6 ones), and the material one(4 ones). On the base of these 18 elements, the importance degree of each element was examined by using 5-point Likert scale. The subjects were 299 housewives living in apartment houses in Jangyu new town, Gimhae. The subjects perceived strongly the importance of eco-friendly design elements, but many of them did not know about Green Building Certification Criteria. Overall importance of 18 elements by the residents was very high. Also, the indoor environmental climate area was considered as the most important one, followed by the energy and resource saving area, the material area, and the ecological environment one.

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Applications of Sugarcane by-products to mitigate climate change in Ethiopia

  • Habte, Lulit;Mulatu, Dure;Ahn, Ji Whan
    • 에너지공학
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    • 제27권3호
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    • pp.36-40
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    • 2018
  • Climate change is one of the major issues in both the developed and developing world. Greenhouse gas (GHG) emission is one of the implications for climate change. It is increasing rapidly. Although the emission is much less when compared to the rest of the world, Ethiopia has also faced this global issue. The major source for GHG emission in Ethiopia is agriculture. Therefore, the agriculture sector has to be given more attention in Ethiopia. To overcome the problem, Climate-Resilient Green Economy (CRGE) strategy has been initiated. One way of executing this target is to create a sustainable and environmentally friendly pathway to use agricultural byproducts. Sugarcane is one of the major plants in Ethiopia. Its byproducts are bagasse, molasses, and press mud. Since it is a waste product, it is economical and creates a sustainable and green environment by reducing GHG emissions. Sugarcane byproducts have versatile applications like as fuel, as cement replacing material, as a mitigation for expansive soils, as biosorbent for the treatment of water and wastewater and also as a wood material. However, Ethiopia has not used this byproduct massively as it is readily available. This paper reviews the possible applications of sugarcane byproducts to mitigate climate change.

CaMoO4:Tb3+ 녹색 형광체 분말과 박막의 제조와 발광 특성 (Synthesis and Emission Properties of CaMoO4:Tb3+ Green Phosphor Powders and Thin Films)

  • 전용일;조신호
    • 한국전기전자재료학회논문지
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    • 제26권4호
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    • pp.264-270
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    • 2013
  • $CaMoO_4:Tb^{3+}$ green phosphor powders and thin films were successfully prepared by using the solid-state reaction method and the radio-frequency magnetron sputtering technique, respectively. The crystalline structure of all phosphor powders with different $Tb^{3+}$ ion concentrations was found to be a tetragonal system with the maximum diffraction intensity at $28.58^{\circ}$, while that of the phosphor thin films, irrespective of the type of substrate, was amorphous. As for the phosphor powders, the grain particles showed the chain-like patterns with inhomogeneous size distribution, the excitation spectra were composed of a broad band peaked at 307 nm and two small narrow bands centered at 381 and 492 nm, and the highest green emission spectrum was observed at 0.01 mol of $Tb^{3+}$ ions. As for the phosphor thin films, the average transmittance exceeding 85% was measured in the 400~1,100 nm range and the optical band gap showed a significant dependence on the type of substrate.

Er 이온 주입된 GaN의 광학적 특성 (Optical Properties of Er-implanted GaN)

  • 손창식
    • 한국전기전자재료학회논문지
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    • 제18권12호
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    • pp.1101-1105
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    • 2005
  • We have investigated the optical properties of Erbium (Er)-implanted GaN by photoluminescence (PL). Various doses of Er ion were implanted on GaN epilayers by ion implantation. Visible green emission lines due to inner 4f shell transitions for $Er^{3+}$ were observed from the PL spectrum of Er-implanted GaN. The emission spectrum consists of two narrow green lines at 537 and 558 nm. The green emission lines are identified as $Er^{3+}$ transitions from the $^{5}H_{11/2}$ and $^{4}S_{3/2}$ levels to the $^{4}I_{15/2}$ ground state. The stronger peaks in the case with the dose of $5{\times}10^{14}cm^{-2}$, together with the relatively higher intensity of the $Er^{3+}$ luminescence in the lower doped sample. It implies that some damage remains in the case with the dose of $1{\times}10^{16}cm^{-2}$. The peak positions of emission lines due to inner 4f shell transitions for $Er^{3+}$ do not change with increasing temperature. It indicates that $Er^{3+}$ related emission depends very little on the ambient temperature.

SOI NMOSFET을 이용한 Photo Detector의 특성 (Properties of Photo Detector using SOI NMOSFET)

  • 김종준;정두연;이종호;오환술
    • 한국전기전자재료학회논문지
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    • 제15권7호
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    • pp.583-590
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    • 2002
  • In this paper, a new Silicon on Insulator (SOI)-based photodetector was proposed, and its basic operation principle was explained. Fabrication steps of the detector are compatible with those of conventional SOI CMOS technology. With the proposed structure, RGB (Read, Green, Blue) which are three primary colors of light can be realized without using any organic color filters. It was shown that the characteristics of the SOI-based detector are better than those of bulk-based detector. To see the response characteristics to the green (G) among RGB, SOI and bulk NMOSFETS were fabricated using $1.5\mu m$ CMOS technology and characterized. We obtained optimum optical response characteristics at $V_{GS}=0.35 V$ in NMOSFET with threshold voltage of 0.72 V. Drain bias should be less than about 1.5 V to avoid any problem from floating body effect, since the body of the SOI NMOSFET was floated. The SOI and the bulk NMOSFETS shown maximum drain currents at the wavelengths of incident light around 550 nm and 750 nm, respectively. Therefore the SOI detector is more suitable for the G color detector.

Estimation of Permeability of Green Sand Mould by Performing Sensitivity Analysis on Neural Networks Model

  • Reddy, N. Subba;Baek, Yong-Hyun;Kim, Seong-Gyeong;Hur, Bo Young
    • 한국주조공학회지
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    • 제34권3호
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    • pp.107-111
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    • 2014
  • Permeability is the ability of a material to transmit fluid/gases. It is an important material property and it depends on mould parameters such as grain fineness number, clay, moisture, mulling time, and hardness. Modeling the relationships among these variable and interactions by mathematical models is complex. Hence a biologically inspired artificial neural-network technique with a back-propagation-learning algorithm was developed to estimate the permeability of green sand. The developed model was used to perform a sensitivity analysis to estimate permeability. The individual as well as the combined influence of mould parameters on permeability were simulated. The model was able to describe the complex relationships in the system. The optimum process window for maximum permeability was obtained as 8.75-10.5% clay and 3.9-9.5% moisture. The developed model is very useful in understanding various interactions between inputs and their effects on permeability.

창호 블라인드와 상변화물질 적용에 의한 냉방 에너지 사용량 절감효과에 대한 검토 연구 (Experimental Study of Cooling Energy Saving Verification Using Blinds and Phase Change Material(PCM))

  • 송영학;김기태;구보경;이건호
    • 설비공학논문집
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    • 제26권1호
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    • pp.26-31
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    • 2014
  • This study looks into changing building energy use by application of phase change material (PCM). PCM does not need extra energy for operation and is used for reducing building energy use and, CO2 output by displaying semi-permanent effects after installation. It also is able to avoid the maximum electric power time-zone by inducing a time lag phenomenon of cooling and heating loads with high thermal capacity using latent heat. To verify the efficiency of blinds and PCM, tests about the PCM operation mechanism using air conditioning machinery and nocturnal panel cooling were done. In the test results of the case using PCM installation, a $45^{\circ}$ blind angle with machinery air conditioning and nocturnal panel cooling at the same time shows a 22 percent energy saving effect against general space. The test results of each case were compared and analyzed based on the blind and window opening settings. Finally, the energy reduction of existing buildings using PCM application was reviewed based on the final measurement results.

V의 고용이 Malayaite의 결정 및 발색에 미치는 영향 (Effect of V-doping on Colour and Crystallization of Malayaite Pigments)

  • 주인돈;이병하
    • 한국세라믹학회지
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    • 제47권4호
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    • pp.302-307
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    • 2010
  • This study aims to synthesize emerald-green malayaite pigments using $CaCO_3$, $SiO_2$, $SnO_2$ and $V_2O_5$. For this purpose, the optimum composition is $CaV_{0.25}Sn_{0.687}SiO_5$ and heating condition is at $1250^{\circ}C$ for 6 h of soaking time. The samples were characterized by X-ray diffraction (XRD), the Fourier Transform Infrared Spectrometers(FT-IR), the Raman Spectrometer, Scanning Electron Microscope(SEM) and the UV/Vis spectroscopy. The substituted V ion for Sn was observed to be quadrivalence. The analytical results of the synthesized pigment showed the tetragonal crystal, a typical form of Malayaite, and the particle size to be approximately $5{\sim}10\;{\mu}m$. The color in lime glaze added 12 wt% pigment was emerald green, and CIE Lab parameters are $L^*=67.73$, $a^*=-12.39$ and $b^*=9.28$.

On the Accumulation of Radioactive Materials in Marine Organisms Along the Coast of Korea 1. Gross Alpha and Beta Activities in Several Edible Marine Algae

  • Yang, Kyung Rin;Pak, Chan Kirl;Lee, In Kyu
    • 한국해양학회지
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    • 제10권1호
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    • pp.17-24
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    • 1975
  • In order to clarify the accumulation of radioactive materials in marine organisms of Korea, the present investigation is carried out with 54 samples of edible seaweeds collected from eight sampling sites along the coast of Korea during September, 1973 and April, 1974. In this paper, ash contents, gross alpha activities and gross beta activities are detected. The ash content is 7.53- 15.95% in the species investigated. Among the algal phyla it is about 13.13% in green algae, 12.77% in brown algae, and 10.77% in red algae on an average. On the other hand, gross alpha activities fluctuate from 180.0 pCi/Kg to 1082.6 pCi /Kg-fresh material experimented, and are 530.72 pCi/Kg on an average. They increase from green to red and brown algae, in turn. The activities in a single species collected at the same season increse from eastern to western and southern coasts of Korea, in turn. Gross beta activities, however, fluctuate from 2.40 nCi/Kg to 22.14 nCi/Kg-fresh material experimented, and 9.03 nCi/Kg on an average. They increase also from green to red nd brown algae, in turn. The gross beta activities are specially higher in Sargassum thunbergii, 22.14 nCi/Kg It is expected that this plant could be an indicator to detect the activities in the marine algae along the coast of Korea.

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