• Title/Summary/Keyword: Green Performance

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Synthesis and Photovoltaic Properties of a Low Band Gap Polymer for Organic Solar Cell (유기태양전지를 위한 작은 밴드갭 고분자의 합성과 광전특성)

  • Woo, Yong-Ho;Lee, Hyo-Sang;Park, Sungnam;Choi, E-Joon;Kim, BongSoo
    • Polymer(Korea)
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    • v.39 no.1
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    • pp.71-77
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    • 2015
  • We synthesized a low band gap alternating copolymer containing electron-rich units (i.e. dithienosiloles and benzodithiophenes) and electron-deficient units (i.e. difluorobenzothiadiazoles) for high performance organic solar cells. The polymer was prepared by the Stille coupling reaction and characterized using $^1H$ NMR, GPC, TGA, UV-visible absorption spectroscopy, and cyclic voltammetry. Solar cells were fabricated in a structure of ITO/PEDOT:PSS/polymer: $PC_{70}BM/Al$ with five different blending ratios of polymer and $PC_{70}BM$ (1:1.5, 1:2, 1:3, 1:3.5 and 1:4 by weight ratio). The best efficiency was achieved from the 1:3 ratio of polymer and $PC_{70}BM$ in the photoactive layer, and TEM revealed that there is an optimal nanoscale phase separation between polymer and $PC_{70}BM$ in the 1:3 ratio blend film.

A Study on the Non-residential Building Envelope Remodeling for Energy Efficiency (비주거용 건물의 외피 리모델링을 통한 에너지성능향상 방안에 관한 연구)

  • Jang, Hyun-Sook;Lee, Sang-Ho
    • Korean Journal of Construction Engineering and Management
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    • v.13 no.6
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    • pp.3-12
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    • 2012
  • The slowdown of private building industry resulted in growth of remodeling market as a way to improve energy performance. Remodeling is considered more cost-effective and eco-friendly approach for energy efficient building than new construction. Since 2008, Seoul has promoted Building Retrofit Project (BRP) preponderantly to attract energy-saving renovation by supporting building owners to switch building system into energy-saving system when they remodel their old buildings. According to 2012 press release, 254 Private sectors participated in this green building project and annually reduced 41000ton of greenhouse gas emission, 14000TOE, which also result in 7.5 billion won energy cost savings per year. The paper focuses on the building envelope remodeling as a way to improve energy efficiency. Different components of the building envelope such as wall insulation, window, and shading, were applied to the baseline model and the comparison was analyzed to come up with the ideal solution. This study only assesses the building envelope as to suggest the way to redesign the better energy performing building. Offering solution focusing on the architectural feature is essential because it will provide basic information and standard when remodeling a building for energy efficiency, especially, for the nonresidential buildings used as rental offices.

Traffic Signal Control Strategy for Passive Tram Signal Priority on City Arterial (도시부 간선도로의 고정식 트램 우선신호를 위한 교통신호운영 전략)

  • Jeong, Young-Je;Kim, Young-Chan;Kim, Dae-Ho
    • The Journal of The Korea Institute of Intelligent Transport Systems
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    • v.10 no.1
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    • pp.27-41
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    • 2011
  • This research proposes new tram signal coordination model, called MAXBAND MILP-Tram for a passive tram signal priority strategy. The proposed model was formulated based on the MAXBAND model that was a traditional arterial signal optimization model. The model could calculate the bandwidth solutions for both general-purpose-lane traffic and median-tram-lane traffic. Lower progression speed are applied for the tram traffic considering lower running speed and dwell time at the stations. A phase sequence procedure determines the green times and left-turn phase sequences for tram traffic in median tram lane. To estimate the performance of the MILP-Tram model, the control delay of trams were estimated using the micro simulation model, VISSIM. The analysis results showed 57 percent decrease of the tram compared to the conventional signal timing model. The delay for car, however, increased 18 percent. The sensitivity analysis indicated that the passive tram signal priority strategy using the offset and phase sequence optimization was effective in reducing the person delay under the congested traffic condition.

Eco-Friendly Light Emitting Diodes Based on Graphene Quantum Dots and III-V Colloidal Quantum Dots

  • Lee, Chang-Lyoul
    • Proceedings of the Korean Vacuum Society Conference
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    • 2015.08a
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    • pp.65-65
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    • 2015
  • In this talk, I will introduce two topics. The first topic is the polymer light emitting diodes (PLEDs) using graphene oxide quantum dots as emissive center. More specifically, the energy transfer mechanism as well as the origin of white electroluminescence in the PLED were investigated. The second topic is the facile synthesis of eco-friendly III-V colloidal quantum dots and their application to light emitting diodes. Polymer (organic) light emitting diodes (PLEDs) using quantum dots (QDs) as emissive materials have received much attention as promising components for next-generation displays. Despite their outstanding properties, toxic and hazardous nature of QDs is a serious impediment to their use in future eco-friendly opto-electronic device applications. Owing to the desires to develop new types of nanomaterial without health and environmental effects but with strong opto-electrical properties similar to QDs, graphene quantum dots (GQDs) have attracted great interest as promising luminophores. However, the origin of electroluminescence (EL) from GQDs incorporated PLEDs is unclear. Herein, we synthesized graphene oxide quantum dots (GOQDs) using a modified hydrothermal deoxidization method and characterized the PLED performance using GOQDs blended poly(N-vinyl carbazole) (PVK) as emissive layer. Simple device structure was used to reveal the origin of EL by excluding the contribution of and contamination from other layers. The energy transfer and interaction between the PVK host and GOQDs guest were investigated using steady-state PL, time-correlated single photon counting (TCSPC) and density functional theory (DFT) calculations. Experiments revealed that white EL emission from the PLED originated from the hybridized GOQD-PVK complex emission with the contributions from the individual GOQDs and PVK emissions. (Sci Rep., 5, 11032, 2015). New III-V colloidal quantum dots (CQDs) were synthesized using the hot-injection method and the QD-light emitting diodes (QLEDs) using these CQDs as emissive layer were demonstrated for the first time. The band gaps of the III-V CQDs were varied by varying the metal fraction and by particle size control. The X-ray absorption fine structure (XAFS) results show that the crystal states of the III-V CQDs consist of multi-phase states; multi-peak photoluminescence (PL) resulted from these multi-phase states. Inverted structured QLED shows green EL emission and a maximum luminance of ~45 cd/m2. This result shows that III-V CQDs can be a good substitute for conventional cadmium-containing CQDs in various opto-electronic applications, e.g., eco-friendly displays. (Un-published results).

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Photoluminescence Properties of $Zn_{2-x-y}SiO_4:Mn_x,\;M_y$ Phosphors ($Zn_{2-x-y}SiO_4:Mn_x,\;M_y$계 형광체의 발광특성)

  • Cho, Bong Hyun;Sohn, Kee Sun;Park, Hee Dong;Chang, Hyun Ju;Hwang, Taek Sung
    • Journal of the Korean Chemical Society
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    • v.43 no.2
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    • pp.206-212
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    • 1999
  • The main objective of the present investigation is to improve the photoluminescent performance of existing $Zn_2SiO_4:Mn$ phosphors by introducing a new co-dopant. The co-doping effect of Mg and/or Cr upon emission intensity and decay time was studied in the present investigation. The co-dopants incorporated into the $Zn_2SiO_4:Mn$ phosphors are believed to alter the internal energy state so that the change in emission intensity and decay time can be expected. Both Mg and Cr ions have a favourable influence on photoluminescence prpperties, for example, the Mg ion enhances the intensity of manganese green emission and the Cr ion shortens the decay time. The enhancement in emission intensity of $Zn_2SiO_4:Mn,\;Mg$ phosphors was interpreted by taking into account the result from the DV-X${\alpha}$ embedded cluster calculation. On the other hand, the energy transfer between Mn and Cr ions was found to be responsible for the shortening of decay time in$Zn_2SiO_4:Mn,\;Cr$ phosphors.

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Implementation of AC Direct Driver Circuit for Ultra-slim LED Flat Light System (초슬림 LED 면조명 기구용 교류 직결형 구동 회로 구현)

  • Cho, Myeon-Gyun;Choi, Hyo-Sun;Yoon, Dal-Hwan
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.13 no.9
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    • pp.4177-4185
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    • 2012
  • LEDs are becoming the most suitable candidate replacing traditional fluorescent lamps because of its eco-friendly characteristics. LEDs are also actively used to design green building system and to make outdoor billboard as a back-light system due to its high energy efficiency. In this paper, we have developed AC direct driver for $12{\times}12$ FLB(flexible LED board) and LED flat light without SMPS. It has LID-PC-R101B driver IC that can support the high power factor and be composed of LED switching circuit in group. Also, an elaborate system designs can guarantee a high luminous efficiency, a high reliability and a low power consumption. The proposed FLB has the ultra slim shape of $450{\times}450$ mm, width of 4 mm and weight of 280 g. In the end, we have developed a prototype of FLB for billboard and flat light for room lighting with AC direct driver iposrder to verify the performance of the proposed system.

A study on the curing characteristics of multi-concentrating UV-LED Curable Coating (다중 집광성 UV-LED 경화형 코팅의 경화특성에 관한 연구)

  • Jung, Chan-Gwon;Kim, Beom-Su;Park, Dae-Hee
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.19 no.10
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    • pp.339-345
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    • 2018
  • We investigated the curing properties of cured coatings for a multi-focal UV-LED. The coatings are for LEDs that operate at multiple UV wavelengths, unlike conventional single-wavelength UV-LEDs. Using UV-LED light sources with wavelengths of 365, 395, 420, and 450 nm, we analyzed the optical characteristics such as the direction of light flux and light source. We also analyzed the curing characteristics at each UV-LED wavelength to optimize the LED for composite wavelengths. The curing performance state was predicted through computer simulation for when the multiple wavelengths of UV light sources are superimposed, and then actual LEDs were designed and fabricated. To improve the internal high-speed curing, a multi-spot module was fabricated, in which each LED is condensed, and multiple wavelengths are synthesized and condensed at the same position. The adhesive strength, surface hardness, and internal hardness of the curing agent were tested by varying the wavelength combination conditions. The surface hardening and internal hardening were compared and analyzed using a hardness tester and FT-IR analyzer. As a result, the characteristics of the surface and internal hardness were improved by a multi-spot method in which four wavelengths were overlapped in a UV-LED rather than a single wavelength.

Simultaneous Analytical Techniques for Determination of 8 Synthetic Food Colors in Foods by HPLC (HPLC를 이용한 식품중 식용타르색소 8종의 동시분석)

  • Park, Sung-Kwan;Lee, Chang-Hee;Park, Jae-Seok;Yoon, Hae-Jung;Kim, So-Hee;Hong, Yeun;Lee, Jong-Ok;Lee, Chul-Won
    • Analytical Science and Technology
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    • v.13 no.3
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    • pp.378-384
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    • 2000
  • This Study has been carried out to develop a method of analysis of 8 permitted synthetic food colors [including Brilliant Blue FCF(B1), Indigocarmine (B2), Fast green FCF(G3), Amaranth (R2), Erythrosine (R3), Allura red (R40), Tartrazine (Y4), Sunset Yellow FCF (Y5)] in Korean foods by HPLC. After adjusting to 0.5% HCl, each of the food colors extracted was eluted by Sep-pak $C_{18}$ cartridge. Eluates were then determined by high performance liquid chromatograph with a UV-VIS detector. Recoveries of the 8 synthetic food colors were found to be 81.2-98.0% for soft drinks, 80.6-96.1% for candy, 79.8-96.3% for chewing gum, 76.5-91.7% for cereals, 79.9-93.8% for ice cream and 78.6-94.7% for jelly, respectively. The detection limits were $0.05-0.1{\mu}g/g$.

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Changes of Tissue N Content and Community Structure of Macroalgae on Intertidal Rocky Shores in Tongyeong Area due to Sewage Discharge (통영 지역의 암반 조간대에서 배출수 유입으로 인한 해조 군집 구조와 엽체 내 질소 함량의 변화)

  • Kang, Yun-Hee;Park, Sang-Rul;Oak, Jung-Hyun;Lee, Jin-Ae;Chung, Ik-Kyo
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.42 no.3
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    • pp.276-283
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    • 2009
  • Enrichment in nutrients coming from urban sewage outfalls can lead to eutrophication in coastal areas, which can also change the species composition and community structure of macro algal communities. We investigated the structure of the macro algal community within three rocky shores in order to assess any possible differences in their characteristics. Site 1 was located near Tongyeong city's sewage outfall, Site 2 was located near a public beach area, and Site 3 faced open channel of the Ocean. All three sites were located within the same stretch of the coast, where Site 2 was located between sites 1 and 3. We measured the nutrient concentration in water and the tissue nitrogen content in macro algae samples. Nutrients in the water column surrounding site 1 were high in ammonium ($30.2\pm1.8{\mu}M$), nitrate ($26.2{\pm}0.1{\mu}M$), and phosphate ($2.7{\pm}0.1{\mu}M$) content, and were characterized by low numbers of macroalgal species and species and a low species diversity index. In contrast, site 3 exhibited relatively low nutrient concentration levels and a high number of macroalgal species and a high species diversity index. Comparative analysis showed that the tissue nitrogen content of macroalgae were significantly (P<0.05) affected by the nutrient concentration in the water column. The tissue nitrogen content of green algae within site 1 was higher than the others sites. However, the tissue nitrogen content of brown algae was similar at all three sites. Thus, the tissue nitrogen content of macro algae and the macro algal community structure of intertidal rocky shores were dependent on location and the performance of macroalgal communities was dependent on water quality.

Determination of Pyribencarb and Its Metabolite KIE-9749 in Agricultural Commodities by High-Performance Liquid Chromatography (액체크로마토그래피를 이용한 농산물중 pyribencarb와 대사물 KIE-9749의 잔류 분석법)

  • Kwon, Hyeyoung;Hong, Su-Myeong;Kim, Taek-Kyum;Kim, Hyung-Jin;Moon, Byeong-Chul;Kyung, Kee-Sung
    • The Korean Journal of Pesticide Science
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    • v.20 no.3
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    • pp.236-246
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    • 2016
  • The aim of this study was to develop an analytical method for the determination of pyribencarb and its metabolite KIE-9749 in agricultural commodities. The experiment was performed with a range of concentrations $0.05{\sim}2.5{\mu}g/g$ in apple, green pepper, potato, hulled rice, soybean, pear, peach, grape and cucumber. Each samples were extracted with acetone and cleaned by dichloromethane/saline water partition and purified with Florisil solid phase extraction (SPE) cartridge and aminopropyl SPE cartridge. Pyribencarb and KIE-9749 were separated and quantified by HPLC/UVD at 265nm using acetonitrile and water as mobile phase. The recoveries of pyribencarb and KIE-9749 were within 78.3~108.4% and 73.9~113.7% with RSD below 12.2% and 15.0%, respectively. The limits of quantification (LOQ) were both $0.05{\mu}g/g$. LC/ESI-MS/MS was optimized for confirmation of residue identity.