• Title/Summary/Keyword: Luminous property

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Development of a Very Small LED Lamp with a Low-Thermal-Resistance Lead Frame for an LCD Backlight Unit

  • Yu, Soon-Jae;Kim, Do-Hyung;Choi, Yong-Seok;Kim, Hee-Tae
    • Journal of Information Display
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    • v.10 no.2
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    • pp.49-53
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    • 2009
  • In this study, a very small LED packaging lead frame with a low thermal resistance was developed. The cost of the package process was reduced by the use of many small LED lamps, which increased the light emission efficiency. Compared to the large lead frame lamp, however, the optical property of the small LED packaging lead frame lamp was not sufficiently improved because its reflection structure was changed and its reflection area was reduced. The luminous efficiency of the LED lamp reaches 58 lm/W at the current density of 0.16 A/$cm^2$. Using the LED lamps, 46-inch LCD BLU was manufactured. The BLU-made LED lamps have a low power consumption of 146 W and have a slim (10-mm-thick) BLU, keeping good uniformity in terms of brightness, and maintaining good thermal properties.

Potentiality of Green Fluorescent Protein (GFP) from Aequorea victoria - A Mini Review

  • Karagozlu, Mustafa Zafer;Kim, Se-Kwon
    • Journal of Marine Bioscience and Biotechnology
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    • v.5 no.4
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    • pp.26-32
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    • 2011
  • Green fluorescent protein (GFP), a very important biological agent that involves shifting the color of bioluminescence from blue to green in luminous coelenterates and to increase the quantum yield of light emission. GFP discovered in medusa, Aequorea victoria is a key factor of various biotechnological and cell biological applications. Beside these applications, GFP of A. victoria is generally stable, which does not require co-factors for activity and can be functionally expressed in different bacterial species. This property of GFPs from A. victoria permits them to be a unique tool to monitor gene expression and protein localization in different organisms. The present review brings out the past milestones and future perspectives on GFPs, with an elaborative reviewing on its applications.

A study on the manufacturing of durable and long afterglow phosphorescent paints added with rare earths for night visibility of pavement (야간 시인성 확보를 위한 희토류 첨가 고내구성 장잔광 축광도료 제조에 관한 연구)

  • Eunseok Woo;Yunseok Noh;Jinho Lee;Yong-Wook Choi;JongGee Kim
    • Journal of the Korean institute of surface engineering
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    • v.56 no.2
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    • pp.152-159
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    • 2023
  • The night visibility of pavement is being considered as a global issue in the field of traffic safety. Although the spreading glass beads on the lane paints has been mainly used to secure night-visibility by utilizing the effect of retroreflection, obvious shortcoming of this method is that retroflection does not occur in the range where the headlights do not reach the glass beads. The use of functional paints including phosphorescent constituents could be a solution for overcoming fore-mentioned problem. SrAl2O4 based chemicals have not only good phosphorescent property, but also are chemically stable compared to existing ZnS based materials. However, this chemicals also need the improvement due to slightly reduced luminous effect in time. Herein, we developed novel paints showing enhanced phosphorescent properties by putting rare earth elements such as Eu, Dy and Y into SrAl2O4. These prepared phosphorescent pigments have displayed improved properties in terms of durability and long afterglow. For instance, the property of afterglow has been persisted after 5 hours with luminace of 20.6 mcd/m2.

Effect of PVA Polymerization on Synthesis of YAG:Ce3+ Phosphor Powders Prepared by a Solid-liquid Hybrid Route (PVA 중합도가 고상-액상 혼합 방식에 의한 YAG:Ce3+ 형광체 분말 합성에 미치는 영향)

  • Kim, A-Reum;Lee, Sang-Jin
    • Journal of the Korean Ceramic Society
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    • v.51 no.5
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    • pp.424-429
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    • 2014
  • YAG:$Ce^{3+}$ phosphor powders were synthesized using $Al(OH)_3$ seeds by means of a PVA-polymer-solution route. Various types of PVA with different molecular weights (different polymerization) were used. All dried precursor gels were calcined at $500^{\circ}C$ and then heated at $1500^{\circ}C$ in a mix of nitrogen and hydrogen gases. The final powders were characterized via XRD, SEM, PSA, PL, and PKG analyses. The phosphor properties and morphologies of the synthesized powders were dependent on the PVA type. As the molecular weight of the PVA was increased, the particle size gradually decreased with agglomeration, and the luminous intensity of the phosphor increased. However, the phosphor powder prepared from the PVA exhibiting very high molecular weight, showed a 531 nm (blue) shift from the 541 nm (yellow) wavelength of the YAG:$Ce^{3+}$ phosphor. Finally, the synthesized YAG:$Ce^{3+}$ phosphor powder prepared from the PVA with 89,000 - 98,000 molecular weight showed phosphor properties similar to those of a commercial phosphor powder, but without a post-treatment process.

Technological Trend of Functional Clothing by Analysis of Korean Patent (국내 특허분석을 통한 기능성이 적용된 의복의 기술 동향)

  • Kim, Ho Jung
    • Fashion & Textile Research Journal
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    • v.16 no.1
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    • pp.160-166
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    • 2014
  • Patent and utility indicate international competitiveness in the knowledge-based society of the $21^{st}$century where both the quantity and quality of the nation's scientific intelligence and innovative technology represent key criteria to evaluate its strength. Thus, discerning the trends of patents is inevitable for further development. This research is centered on apprehending the technological current of the functional clothing of Korea, through an analysis of patents and utility models. The number of patent applications in Korea was low until the mid-1990s. However, it began to grow rapidly in the 2000s and the number of patents surpassed the number of utility starting in 2006. The technological level of invention in this field has been turned into a higher level. The IPC code with the strongest application was the field related to temperature controllable clothing (A41D 13/005), followed by surgeon or patient apparel related fields (A41D 13/12), and reflective or luminous safety devices (A41D 13/01).The main technological idea was to give functionality that could protect the human body from various hazards and represents the goal of various applied techniques. About 66% of domestic patent applications belong to individuals; however, the proportion of corporate or institutional applications(including universities) remains poor. Consequently, more systematic and long-term support for research on patents is required.

Luminous phosphor with modified surface composition and microwave treatment for plasma planar back light

  • Ting, Chu-Chi;Cheng, Hao-Ping;Hsieh, Yu-Heng;Sun, Oliver;Chen, San-Yuan;Lin, Chin-Ching;Kuo, Kuan-Ting;Lee, Shu-Ping
    • 한국정보디스플레이학회:학술대회논문집
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    • 2005.07b
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    • pp.1534-1535
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    • 2005
  • Highly luminescent efficiency phosphors have been successfully produced by surface modification and microwave irradiation treatment. The SEM image and XRD analysis reveal that the surface morphology of the white-light phosphors can be notably modified by microwave irradiation and exhibit with better crystalline property. The VUV PL spectra show that the microwave irradiation treatment can effectively enhance the luminescent efficiency by a factor of 1.5 times for intensity compared to that without microwave treatment. A further improvement in all visible emission can be made by modifying surface composition through MgO coating on the phosphor powder. These results demonstrate that such a simple approach can provide for improving luminescent efficiency of phosphors for the optoelectronic devices.

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Morphological research on radio loud AGN 4C39.25 using KaVA observation

  • Yoo, Hyemin;Sohn, Bong Won;Yi, Sukyong K.
    • The Bulletin of The Korean Astronomical Society
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    • v.40 no.2
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    • pp.36.3-37
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    • 2015
  • 4C39.25 (0923+392) is a distant radio loud AGN placed at redshift 0.695. The motivation of our work is peculiar properties 4C39.25. Firstly, it has a conspicuous distinction of jet direction between kilo-parsec scale observation made by VLA (Kollgaard et al. 1990) and the parsec scale observation by VLBA (Kellermann et al. 1998). This might indicate episodic-jet activity which recently turned on. This object currently shows two stationary compact parsec-scale components which are bright jet component on east and less luminous core on west. Also, it is known that there have been superluminal jet components which are flowing from the core toward east, and then merging with the bright jet component (Marscher et al. 1991, Alberdi et al. 2000, Lister et al. 2013). Although 4C39.25 seems to be a blazar-like source having broad emission lines (SDSS) and superluminal motion, its property that jet component is brighter than the core is different from ordinary blazars. Furthermore, it has young radio galaxy-like properties such as non-variation in total flux (Alberdi et al. 1997, 2000, MOJAVE database) and high frequency peak at spectral energy distribution (Orienti et al 2007). Such complex properties led us to make recent observations to reveal precise properties and new changes of the source. We used Korean VLBI Network (KVN) and VLBI Exploration of Radio Astronomy (VERA) Array (KaVA) which provide high-frequency (23GHz and 43GHz) and high spatial resolution (1.2mas and 0.6mas). Therefore, this system is suitable for morphological and physical research on parsec scale structure. We present results for several epochs observed during 2013 to 2014, mainly focusing on morphological changes of 4C39.25 using KaVA images.

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Heat Sink of LED Lights Using Engineering Plastics (엔지니어링 플라스틱의 LED조명 방열판 적용)

  • Cho, Young-Tae
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.12 no.4
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    • pp.61-68
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    • 2013
  • As an advance study for the development of a heat sink for special purpose high power illumination, an investigation was made to find feasibility for the application of copper plated EP to a heat sink of small LED light of less than 10W installed in commercial product. In this study, the plated heat sink with EP copper was fabricated for the conventional LED light. It was used actually for finding heat radiation property and effectiveness of the heat sink accompanied with measurement of luminous intensity. The heat is radiated by transfer and dissipation only through the copper plated surface due to extremely low heat conductivity of EP in case of EP heat sink; however the total area of the plate plays the function of heat transfer as well as heat radiation in case of the aluminum heat sink. It seems that the volume difference of heat radiating material is so big that the temperature $P_1$ is 9.0~12.3% higher in 3W and 42.7~54.0% higher in case of 6W volume difference of heat radiating material is so big that the temperature $P_1$ is 9.0~12.3% higher in 3W and 42.7~54.0% higher in case of 6W even though heat transfer rate of copper is approximately 1.9 times higher than that of aluminum. It was thought that this is useful to utilize for heat sink for low power LED light with the low heating rate. Also, the illumination could be greatly influenced by the surrounding temperature of the place where it is installed. Therefore, it seems that the illumination installation environment must be taken into consideration when selecting illumination. Further study was expected on order to aims at development of an exterior surface itself made into heat radiation plate by application of this technology in future.

Study on the Efficient White Organic Light-Emitting Diodes using the Material of Binaphthyl Group (Binaphthyl group 기반의 물질을 이용한 효율적인 White OLED 소자에 대한 연구)

  • Yeo, Hyun-Ki
    • Journal of the Korean Applied Science and Technology
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    • v.29 no.3
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    • pp.459-465
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    • 2012
  • We had synthesized a green dopant material based on the binaphthyl group, 7,7'-(2,2'dimethoxy-1,1'-binaphthyl-3,3'-diyl) bis(4-(thiophen -2-yl) benzo[e][1,2,5] thiadiazole (TBT). We also fabricated the white organic light emitting diode (OLED) with a phosphorescent blue emitter : iridium(III)bis[(4,6-di-fluoropheny)-pyridinato -N,C2]picolinate (FIrpic) doped in N,N'-dicarbazolyl-3,5-benzene (mCP) of hole transport type host material and both TBT and bis(2-phenylquinolinato)- acetylacetonate iridium(III) (Ir(pq)2acac) doped in 1,3,5-tris(N-phenylbenzimidazole -2-yl)benzene (TPBi) of electron transport type host material. As a result, the property of white OLED using TBT, which demonstrated a maximum luminous efficiency and external quantum efficiency of 5.94 cd/A and 3.23 %, respectively. It also showed the pure white emission with Commission Internationale de I'Eclairage (CIE) coordinates of (0.34, 0.36) at 1000 nit.

Effect of Changing the Thickness of Charge Control Layer on Performance of Green Phosphorescent Organic Light-Emitting Diodes (녹색 인광 유기발광다이오드에서 전하 조절층의 두께 변화가 성능에 미치는 효과에 대한 연구)

  • Lee, Dong-Hyung;Lee, Seok-Jae;Koo, Ja-Ryong;Lee, Ho-Won;Lee, Song-Eun;Yang, Hyung-Jin;Park, Jae-Hoon;Kim, Young-Kwan
    • Journal of the Korean Applied Science and Technology
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    • v.30 no.2
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    • pp.244-250
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    • 2013
  • We investigated green phosphorescent organic light-emitting diodes (PHOLEDs) with charge control layer (CCL) to produce high efficiency. The CCL and host material which was 4,4,N,N'-dicarbazolebiphenyl (CBP) of bipolar property can control the carrier movement in emitting layer (EML). The performance improvement by the insertion of CCL was realized to the well confined exciton and the reduced triplet exciton quenching effect in EML. Five types of devices (Device A, B, C, D, and E) were fabricated following the thickness of CCL within EML. The properties of device D using optimized thickness of CCL showed external quantum efficiency of 16.22% and luminous efficiency of 55.76 cd/A, respectively.