• Title/Summary/Keyword: Brightness gap

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A Study on Environmental Standards of School Building (교사환경기준에 관한 연구)

  • Hong, Seok-Pyo;Park, Young-Soo
    • The Journal of Korean Society for School & Community Health Education
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    • v.1 no.1
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    • pp.11-43
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    • 2000
  • The purpose of this study was, through analyzing the previous researches, to grasp the present status of environment of school building(ESB), research the sundry records of each element and, through comparative analysis of the standard of ESB in Korea, the United States, and Japan, select the normative standard of ESB, to clarify the point at issue presented in Regulation of Construction & facility Management for Elementary and and Secondary School in Korea, and to suggest an alternative preliminary standard of ESB. To carry out a research for this purpose, these were required: 1. to investigate the existing present status of ESB, 2. to make a comparative analysis of the standard of ESB in each country, 3. to suggest the normative standard of preliminary standard of ESB, 4. to analyze the controversial points of the standard of ESB in Korea, 5. to suggest an alternative preliminary standard of ESB. The conclusions were as follows: 1. Putting, through analyzing the previous researches, the existing present status of ESB together, it seemed that lighting environment, indoor air environment and noise environment were all in poor conditions. 2. In the result of a comparative analysis of the standard of ESB in Korea, Japan and the United States, in Korea the factors of each lighting and indoor air environment were not presented properly, in Japan, in lighting environment aspect, the standard on natural lighting and the factors on brightness were not presented., and in the USA the essential factors of each environment were throughly presented. In the comparison of the standards on each factor, Korea showed that the standard level presented was less properly prescribed than those of the USA and Japan but it also showed that the standard levels prescribed in the USA and in Japan were mostly similar to the standard levels in records investigated. 3. With the result of the normative standard selection on School Builiding environment factor of prescribed in this study, the controversial points of the standard of ESB in Korea were analyzed and the result was utilized to suggest new preliminary standard of ESB. 4. As the result of the analysis of the controversial points of the standard of ESB in Korea, it was found that the standard of ESB in Korea should be established on a basis of School Health Act and be concretely presented in School Health Regulation and School Health Rule. The factors of each environment was improperly presented in the existing standard of ESB in Korea. Moreover the standard of them was inferior to that of the records investigated and those of in the USA and in Japan and it also showed that the standard of it in Korea was improper to maintain Comfortable Learning Environment. 5. A suggested preliminary standard of ESB acquired through above study as follows: 1) In this study a new kind of preliminary standard of ESB is divided into lighting environment, indoor air environment, noise environment, odor environment and for above classification, reasonable factor and standard should be established and the controling way on each standard and countermeasures against it should be considered. 2) In lighting environment, the factors of natural lighting are divided into daylight rate, brightness, glare. In the standard on each factor, daylight rate should secure 5% of a mean daylight rate and 2% of a minimum daylight rate, brightness ratio of maximum illumination to minimum illumination should be under 10:1, and in glare there should not be an occurrence factor from a reflector outside of the classroom. And the factors of unnatural lighting are illumination, brightness, and glare. In the standard on each factor, illumination should be 750 lux or more, brightness ratio should be under 3 to 1, and glare should not occur. And Optimal reflection rate(%) of Colors and Facilities of Classroom which influences lighting environment should be considered. 3) In indoor air environment factors, thermal factors are divided into (1) room temperature, (2) relative humidity, (3) room air movement, (4) radiation heat, and harmful gases (5) CO, (6) $CO_2$ that are proceeded from using the heating fuel such as oval briquettes, firewood, charcoal being used in most of the classroom, and finally (7) dust. In the standard on each factor, the next are necessary; room temperature: $16^{\circ}C{\sim}26^{\circ}C$(summer : $E.T18.9{\sim}23.8^{\circ}C$, winter: $E.T16.7{\sim}21.7^{\circ}C$), relative humidity: $30{\sim}80%$, room air movement: under 0.5m/sec, radiation heat: under $5^{\circ}C$ gap between dry-bulb temperature and wet-bulb temperature, below 1000 ppm of ca and below 10ppm of $CO_2$, dust: below 0.10 $mg/m^3$ of Volume of dust in indoor air, and ventilation standard($CO_2$) for purification of indoor air : once/6 min.(about 7 times/40 min.) in an airtight classroom. 4) In the standard on noise environment, noise level should be under 40 dB(A) and the noise measuring way and the countermeasures against it should be considered. 5) In the standard on odor environment, odor level under Physical Method should be under 2 degrees, and the inspecting way and the countermeasures against it should be considered.

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Field emission properties of SWNTs (single-walled nanotubes) synthesized by arc-discharge method (Arc-Discharge로 합성한 SWNT의 전계방출 특성)

  • Lee, Hyeon-Jae;Lee, Yang-Doo;Moon, Seung-Il;Hwang, Ho-Soo;Han, Jong-Hoon;Yoo, Jae-Eun;Nahm, Sahn;Ju, Byeong-Kwon
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2004.05a
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    • pp.185-188
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    • 2004
  • A diode structure of field emission lamps based upon carbon-nanotube is studied. The single-walled carbon nanotubes(SWNTs) were produced by arc discharge method. We made the 1-inch diode type flat lamp using CNTs. We applied anode voltage gradually to refine the field emission behavior of emitter in dynamic vacuum system to study the emission current. the brightness and efficiency, etc. The field emission properties was estimated by varying gaps between the cathode and anode, contents of the glass frit. The good luminous efficiency is showed in the gap $900{\mu}m$, $1200{\mu}m$ and contents of the proper glass frit. For the upper conditions, the luminous efficiencies were respectively 23.30, 11.12 1m/W.

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Yellow Light-Emitting Poly(p-phenylenevinylene) Derivative with Balanced Charge Injection Property

  • Kim, Joo-Hyun;Lee, Hoo-Sung
    • Bulletin of the Korean Chemical Society
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    • v.25 no.5
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    • pp.652-656
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    • 2004
  • A new luminescent polymer, poly{1,4-phenylene-1,2-ethenediyl-2'-[2"-(4'"-octyloxyphenyl)-(5"-yl)-1",3",4"-oxadiazole]-1,4-phenylene-1,2-ethenediyl-2,5-bis-dodecyloxy-1,4-phenylene-1,2-ethenediyl} (Oxd-PPV), was synthesized by the Heck coupling reaction. Electron withdrawing pendant, conjugated 1,3,4-oxadiazole (Oxd), is on the vinylene unit. The band gap of the polymer figured out from the UV-visible spectrum was 2.23 eV and the polymer film shows bright yellow emission maximum at 552 nm. The electroluminescence (EL) maximum of double layer structured device (ITO/PEDOT:PSS/Oxd-PPV/Al) appeared at 553 nm. Relative PL quantum yield of Oxd-PPV film is 3.6 times higher than that of MEH-PPV film. The HOMO and LUMO energy levels of Oxd-PPV figured out from the cyclic voltammogram and the UV-visible spectrum are -5.32 and -3.09 eV, respectively, so that more balanced hole and electron injection efficiency can be expected compared to MEH-PPV. A double layer EL of Oxd-PPV has an maximum efficiency of 0.15 cd/A and maximum brightness of 464 cd/$m^2$.

Performance Evaluation of 2-Dimensional Light Source using Mercury-free Flat Fluorescent Lamps for LCD Backlight Applications

  • Park, Joung-Hu;Cho, Bo-Hyung;Lee, Ju-Kwang;Whang, Ki-Woong
    • Journal of Power Electronics
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    • v.9 no.2
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    • pp.164-172
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    • 2009
  • Recently, 2-dimensional flat light sources have been attracting much attention for its use in LCD backlight applications because of its high luminous efficiency and uniformity. A long-gap discharge, mercury-tree flat fluorescent lamp has been developed, which shows a high brightness ($>5000\;cd/m^2$) and high luminous efficacy (60 lm/W). Additionally, it has a wide operating margin and stable driving condition with the aid of an auxiliary electrode. For driving the lamp, a narrow pulse power to maintain the glow discharge state is required. Since there has been no research for this kind of lamp driving, this paper proposes a newly developed short-pulse, high-voltage lamp-driving scheme. The proposed lamp system uses a ballast with a coupled-inductor in order to raise the short pulse voltage up to the lamp ignition level and to obtain energy-recovery action during the glow discharge mode. The operation principles are presented and also the system performances such as the lighting efficiency, spatial and angular uniformities are evaluated by hardware experiments. The results show that the proposed lighting system is a good candidate for the next-generation of LCD backlight systems.

The study on the electrical and optical characteristics of a new structure for color ac plasma displays (새로운 전극구조를 가진 ac-PDP의 전기 광학적 특성에 관한 연구 (I))

  • Lee, Woo-Geun;Shin, Joong-Hong;Kim, Joon-Ho;Kim, Doo-Han;Cho, Jung-Soo;Park, Chung-Hoo
    • Proceedings of the KIEE Conference
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    • 1999.07e
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    • pp.2227-2229
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    • 1999
  • As a direct-view flat panel displays, there are many devices, such as plasma display panels(PDPs), vacuum fluorescent displays (VFDs), and light emitting diode(LED). Among these, a PDP is the first type of panel display to be made commercially available. A 'Plasma display' is the general term for a flat display utilizing the light emission that is produced by gas discharge. However, the brightness and Luminous efficiency are still not adequate for consumer television. So, the new sustain electrode type of ac PDP was proposed. By arranging the transparent electrode of quadrangle by zigzag, the area of electrode are reduced, and the length of electrode gap is increased. It generates a high luminous efficiency(corresponding to a 40% improvement of standard type), the same discharge voltage characteristics, and the low power consumption at same luminance.

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A Comparative Study on Light and Space in the Paintings of Rembrandt, Vermeer and Hopper (렘브란트, 베르메르, 호퍼의 회화에 나타난 빛과 공간의 비교 분석에 관한 연구)

  • Kim, Jong-Jin
    • Korean Institute of Interior Design Journal
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    • v.18 no.6
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    • pp.12-19
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    • 2009
  • The characteristics of light in the paintings of Rembrandt van Rijn, Johaness Vermeer and Edward Hopper are very different. While Rembrandt and Vermeer lived in the 17th century, Hopper lived in the 20th century. Although this time gap, comparative study on their light-space relationship is important because there are spatial similarities as well as light differences. Most three painters' works depict interior spaces with one person inside. The interior space is filled with different light and shadow. In the Rembrandt's paintings, only part of the figure is lit in the ambiguous darkness. In the Vermeer's paintings, the soft indirect light is filled in the domestic space and the boundary between the figure and space is blurred. In the Hopper's paintings, the direct sunlight invades the interior and the figure confronts with strong daylight. These light differences were caused by the artists' intentions as well as the environmental situations. 4 case paintings of each artist were analyzed by phenomenological aspects and computerized light brightness test. Scale models were built to re-construct the three different light characteristics. The model experimentation will have potential to develop 2 dimensional art analysis into 3 dimensional space design by means of light. However it was very difficult to construct the three lights, the experimentation shows they have unique characteristics that can be applied to spatial design studies.

An α-cut Automatic Set based on Fuzzy Binarization Using Fuzzy Logic (퍼지논리를 이용한 α-cut 자동 설정 기반 퍼지 이진화)

  • Lee, Ho Chang;Kim, Kwang Baek;Park, Hyun Jun;Cha, Eui-Young
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.19 no.12
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    • pp.2924-2932
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    • 2015
  • Image binarization is a process to divide the image into objects and backgrounds, widely applied to the fields of image analysis and its recognition. In the existing method of binarization, there is some uncertainty when there is insufficient brightness gap between objects and backgrounds in setting threshold. The method of fuzzy binarization has improved the features of objects efficiently. However, since this method sets ${\alpha}$-cut value statically, there remain some problems that important features of objects can be lost during binarization. Therefore, in this paper, we propose a binarization method which does not set ${\alpha}$-cut value statically. The proposed method uses fuzzy membership functions calculated by thresholds of mean, iterative, and Otsu binarization. Experiment results show the proposed method binaries various images with less loss than the existing methods.

High Performance Flexible Inorganic Electronic Systems

  • Park, Gwi-Il;Lee, Geon-Jae
    • Proceedings of the Korean Vacuum Society Conference
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    • 2012.08a
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    • pp.115-116
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    • 2012
  • The demand for flexible electronic systems such as wearable computers, E-paper, and flexible displays has increased due to their advantages of excellent portability, conformal contact with curved surfaces, light weight, and human friendly interfaces over present rigid electronic systems. This seminar introduces three recent progresses that can extend the application of high performance flexible inorganic electronics. The first part of this seminar will introduce a RRAM with a one transistor-one memristor (1T-1M) arrays on flexible substrates. Flexible memory is an essential part of electronics for data processing, storage, and radio frequency (RF) communication and thus a key element to realize such flexible electronic systems. Although several emerging memory technologies, including resistive switching memory, have been proposed, the cell-to-cell interference issue has to be overcome for flexible and high performance nonvolatile memory applications. The cell-to-cell interference between neighbouring memory cells occurs due to leakage current paths through adjacent low resistance state cells and induces not only unnecessary power consumption but also a misreading problem, a fatal obstacle in memory operation. To fabricate a fully functional flexible memory and prevent these unwanted effects, we integrated high performance flexible single crystal silicon transistors with an amorphous titanium oxide (a-TiO2) based memristor to control the logic state of memory. The $8{\times}8$ NOR type 1T-1M RRAM demonstrated the first random access memory operation on flexible substrates by controlling each memory unit cell independently. The second part of the seminar will discuss the flexible GaN LED on LCP substrates for implantable biosensor. Inorganic III-V light emitting diodes (LEDs) have superior characteristics, such as long-term stability, high efficiency, and strong brightness compared to conventional incandescent lamps and OLED. However, due to the brittle property of bulk inorganic semiconductor materials, III-V LED limits its applications in the field of high performance flexible electronics. This seminar introduces the first flexible and implantable GaN LED on plastic substrates that is transferred from bulk GaN on Si substrates. The superb properties of the flexible GaN thin film in terms of its wide band gap and high efficiency enable the dramatic extension of not only consumer electronic applications but also the biosensing scale. The flexible white LEDs are demonstrated for the feasibility of using a white light source for future flexible BLU devices. Finally a water-resist and a biocompatible PTFE-coated flexible LED biosensor can detect PSA at a detection limit of 1 ng/mL. These results show that the nitride-based flexible LED can be used as the future flexible display technology and a type of implantable LED biosensor for a therapy tool. The final part of this seminar will introduce a highly efficient and printable BaTiO3 thin film nanogenerator on plastic substrates. Energy harvesting technologies converting external biomechanical energy sources (such as heart beat, blood flow, muscle stretching and animal movements) into electrical energy is recently a highly demanding issue in the materials science community. Herein, we describe procedure suitable for generating and printing a lead-free microstructured BaTiO3 thin film nanogenerator on plastic substrates to overcome limitations appeared in conventional flexible ferroelectric devices. Flexible BaTiO3 thin film nanogenerator was fabricated and the piezoelectric properties and mechanically stability of ferroelectric devices were characterized. From the results, we demonstrate the highly efficient and stable performance of BaTiO3 thin film nanogenerator.

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Analysis of emotional images according to eyes shapes and smoky makeup tone (눈 형태에 따른 스모키 메이크업의 감성 이미지)

  • Kim, Min-Kyung;Ryu, Hee-Wook
    • Science of Emotion and Sensibility
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    • v.14 no.2
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    • pp.321-330
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    • 2011
  • Images of smoky make up illustrations with different the brightness tones for typical Korean eyes (standard one, small single eyelid and tailed up style) were systematically analyzed using vision-based emotional descriptive language for students majoring makeup and professional group. We identified that various images could be expressed by changing smoky makeup tones on eyes types through analysis of the emotional descriptive language. The smoky make up image recognition of smoky make up illustrations was almost consistent between the students and the professional group, but there was the distinct difference of image perception by two groups for some smoky make up illustrations due to the generation gap as well as their make up expertise and techniques. We suggested the image positioning maps which expressed the emotional reaction felt according to eyes shapes and smoky make up tones. The positioning maps were to provide criteria for various images to be able to express by smoky make up.

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Observation of the Cosmic Near-Infrared Background with the CIBER rocket

  • Kim, Min-Gyu;Matsumoto, T.;Lee, Hyung-Mok;Arai, T.;Battle, J.;Bock, J.;Brown, S.;Cooray, A.;Hristov, V.;Keating, B.;Korngut, P.;Lee, Dae-Hee;Levenson, L.R.;Lykke, K.;Mason, P.;Matsuura, S.;Nam, U.W.;Renbarger, T.;Smith, A.;Sullivan, I.;Wada, T.;Zemcov, M.
    • The Bulletin of The Korean Astronomical Society
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    • v.37 no.1
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    • pp.42-42
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    • 2012
  • The First stars (Pop.III stars) in the universe are expected to be formed between the recombination era at z - 1100 and the most distant quasar (z - 8). They have never been directly detected due to its faintness so far, but can be observed as a background radiation at around 1${\mu}m$ which is called the Cosmic Near-Infrared Background (CNB). Main part of the CNB is thought to be redshifted Lyman-alpha from gas clouds surrounding the Pop.III stars. Until now, the COBE (COsmic Background Explorer) and the IRTS (Infrared Telescope in Space) observed excess emission over the background due to galaxies. To confirm the COBE and the IRTS results and pursue more observational evidences, we carried out the sounding rocket experiment named the Cosmic Infrared Background ExpeRiment (CIBER). The CIBER is successfully launched on July 10, 2010 at White Sands Missile Range, New Mexico, USA. It consists of three kinds of instruments. We report the results obtained by LRS (Low Resolution Spectrometer) which is developed to fill the uncovered spectrum around 1${\mu}m$. LRS is a refractive telescope of 5.5 cm aperture with spectral resolution of 20 - 30 and wavelength coverage of 0.7 to 2.0${\mu}m$. After subtracting foreground components (zodiacal light, integrated star light and diffuse galactic light) from the sky brightness of observed five fields, there remained significant residual emission (even for the lower limit case) consistent with the IRTS and the COBE results. In addition, there exists a clear gap at 0.7 - 0.8${\mu}m$ in the CNB spectrum over the background due to galaxies according to recent results (Matsuoka et al. 2011; Mattila et al. 2011). The origin of the excess emission could be ascribed to the Pop.III stars with its active era of z = 7 - 10.

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