• Title/Summary/Keyword: light panel

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A New Current-Balancing Multi-Channel LED Driver for a Large Screen LCD Backlight Unit (대화면 LCD Backlight를 위한 새로운 전류평형 다채널 LED 구동회로)

  • Lee, Sang-Hyun;Cho, Sang-Ho;Roh, Chung-Wook;Hong, Sung-Soo;Han, Sang-Kyoo
    • The Transactions of the Korean Institute of Power Electronics
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    • v.15 no.2
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    • pp.111-118
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    • 2010
  • Recently, LCD TV using LED backlight has a great attention due to its low power consumption, slim construction, mercury free, wide color gamut and fast response. For the uniform brightness of the LCD panel, multi channel LEDs and DC/DC converter for each LED are required in conventional system. Therefore energy conversion efficiency is poor, the system size bulky and the cost of production high. To overcome these above mentioned drawbacks, a new current-balancing multi-channel LED driver is proposed in this paper. It can not only drive multi-channel LEDs with one DC/DC converter but also provide all LEDs with constant balanced current. To confirm the validity of the proposed driver, its operation and performance are verified on a prototype for 46" LCD TV.

The Dynamic Effects of China's Agricultural Technology Progress and Agricultural Environment Grants on Agricultural Development - Focusing on 3 Dongbei Province in China - (중국의 농업기술진보와 농업환경보조금이 농업발전에 미치는 동태적 파급효과 - 동북 3성을 중심으로 -)

  • Jin, Lin;Mun, Hong Sung
    • Journal of Korean Society of Rural Planning
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    • v.26 no.3
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    • pp.57-65
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    • 2020
  • Agricultural research and development (R&D) investment has contributed not only to agriculture but also to the overall economic growth of the country. The recent arrival of the fourth industrial revolution has raised the need for agricultural R&D as a preparation. Agriculture R&D is directly related to the fourth industrial revolution in the agricultural and livestock sectors that utilize big data, robots, artificial intelligence and cloud. Meanwhile, subsidies or grants are considered the most widely used means of policy. Therefore, in light of the current situation in which Chinese agriculture values R&D investment, this study attempted to analyze the dynamic relationship between variables by establishing a model of agricultural environment subsidy representing the role of government, agricultural technology progress representing existing agricultural R&D investment, agricultural income representing agricultural development and total agricultural output. The analysis results showed that each variable's reaction to the rise in China's agricultural R&D investment has a positive effect on agricultural development, in line with the theory that the investment in science and technology in the agricultural sector has a positive effect. In addition, the response of each variable to China's rising agricultural environment subsidy is shown to have a positive relationship, which can also be said to be in line with the theory that the government's market-friendly intervention is beneficial to economic development.

A Study on the Development of Pattern Design Tool for CCFL Backlight (CCFL 백라이트 패턴 설계툴 개발에 관한 연구)

  • Cho Young-Chang;Choi Byung-Jin;Yoon Jeong-Oh
    • Journal of Korea Society of Industrial Information Systems
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    • v.11 no.2
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    • pp.79-85
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    • 2006
  • As the portable information appliance is developed, the demand of flat panel display equipments and parts are steeply increased. Most of all, the applications of LCD such as LCD TV, monitor, digital camera, CNS(car navigation system) and game machine become diversified. With the result that the number of BLU production enterprise is increased and the research on the design of backlight with the superior optical properties is persistently in progress. In this study we developed the pattern design tools for CCFL(cold cathode flourescent lamp) backlight to improve the conventional pattern design environment in which the pattern is designed manually from the experience and the trial and error. For the verification of our research, we designed the light reflection surface patterns for a real model of backlight and we measured the brightness uniformity using the BM-7. From the brightness uniformity measurement, the BLU designed using the presented tool showed the tolerable performance only in the first try of pattern design rather than the fifth try of pattern design in case of the conventional pattern design.

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Study on Factors to Influence the Hearing-impaired in Relation to Their Using Hearing Aids (청각장애인 보청기사용 영향요인에 관한 연구)

  • Lee, S.D.;Park, J.B.;Yeum, D.M.
    • Journal of rehabilitation welfare engineering & assistive technology
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    • v.8 no.2
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    • pp.119-124
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    • 2014
  • In order to understand those factors to influence the hearing-impaired in connection with their using hearing aids, this study analyzed a total of 521 hearing-impaired people examined by a fourth-year Korea panel survey of employment for the disabled. For the analysis, the study, first, used Andersen-Newman service use model to categorize any influential factors into precedence factors, possibility factors and desire factors, and second, in order to look into how these factors would work on the hearing-impaired's using the hearing aids, the study conducted the logistic regression analysis. According to the results of the analysis, in terms of the precedence factors, when the hearing-impaired people are older and more highly-educated, they would be happier to use the hearing aids while when it comes to the possibility factors, when the gross income of these people is lower but when they are more willing to accept the fact that they have a disability, they would have a fewer problems with using the hearing aids. In addition, regarding the desire factors, when the hearing-impaired people can hear relatively better than the other hearing-impaired, they would be more significantly willing to use the hearing aids. In the light of what has been learned, the study discussed the limits of its research and proposed implications.

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Emission Characteristics of VOCs Distributions in Semiconductor Workplace (반도체 작업환경의 VOCs 농도분포 특성)

  • Lee, Jeong Joo
    • Journal of the Korean Society of Urban Environment
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    • v.18 no.4
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    • pp.503-509
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    • 2018
  • In this study, a Proton-Transfer Reaction-Time-of-Flight Mass spectrometer (PTR-TOF-MS) was used for the continuous monitoring of Volatile Organic Compounds (VOCs) emitted from semiconductor workplace such as photolithography (PHOTO), flat panel display (FPD), organic light emitting diode (OLED), etching (WET) process. The averaged VOCs mixing ratio in the such workplace, PHOTO was 6.5 ppm, FPH was 6.4 ppm, WET was 2.0 ppm and OLED was 1.3 ppm, respectively. The abundance of VOCs in the workplace were methyl ethyl ketone (MEK) with 2.8 ppm (69%) and acetaldehyde with 0.5 ppm (13.2%). Depending on the semiconductor process characteristics, various VOCs have been observed in the workplace. The VOCs mixing ratio are lower than the workplace regulation standard (TWA), it is necessary to continuously monitor and effectively manage these VOCs.

Lateral Resistance of CLT Wall Panels Composed of Square Timber Larch Core and Plywood Cross Bands

  • JANG, Sang Sik;LEE, Hyoung Woo
    • Journal of the Korean Wood Science and Technology
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    • v.47 no.5
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    • pp.547-556
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    • 2019
  • Thinned, small larch logs have small diameters and no value-added final use, except as wood chips, pallets, or fuel wood, which are products with very low economic value; however, their mechanical strength is suitable for structural applications. In this study, small larch logs were sawed, dried, and cut into square timbers (with a $90mm{\times}90mm$ cross section) that were laterally glued to form core panels used to manufacture cross-laminated timber (CLT) wall panels. The surface and back of these core panels were covered with 12-mm-thick structural plywood panels, used as cross bands to obtain three-ply CLT wall panels. This attachment procedure was conducted in two different ways: gluing and pressing (CGCLT) or gluing and nailing (NGCLT). The size of the as-manufactured CLT panels was $1,220mm{\times}2,440mm$, the same as that of the plywood panels. The final wall panels were tested under lateral shear force in accordance with KS F 2154. As the lateral load resistance test required $2,440mm{\times}2,440mm$ specimens, two CLT wall panels had to be attached in parallel. In addition, the final CLT panels had tongued and grooved edges to allow parallel joints between adjacent pieces. For comparison, conventional light-frame timber shear walls and midply wall systems were also tested under the same conditions. Shear walls with edge nail spacing of 150 mm and 100 mm, the midply wall system, and the fabricated CGCLT and NGCLT wall panels exhibited maximum lateral resistances of 6.1 kN/m (100%), 9.7 kN/m (158%), 16.9 kN/m (274%), 29.6 kN/m (482%), and 35.8 kN/m (582%), respectively.

A Study on Establishment of Essential Performance Evaluation Criteria for C-arm Computed Tomography (C-arm CT의 필수 성능평가 기준 마련을 위한 연구)

  • Kim, Eun-Hye;Park, Hye-Min;Kim, Jung-Min
    • Journal of radiological science and technology
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    • v.45 no.2
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    • pp.127-134
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    • 2022
  • In order to overcome the image quality limitations of the conventional C-arm, a flat panel detector (FPD) is used to enhance spatial resolution, detective quantum efficiency, frame rate, and dynamic range. Three-dimensional (3D) visualized information can be obtained from C-arm computed tomography (CT) equipped with an FPD, which can reduce patient discomfort and provide various medical information to health care providers by conducting procedures in the interventional procedure room without moving the patient to the CT scan room. Unlike a conventional C-arm device, a C-arm CT requires different basic safety and essential performance evaluation criteria; therefore, in this study, basic safety and essential performance evaluation criteria to protect patients, medical staff, and radiologists were derived based on International Electrotechnical Commission (IEC) standards, the Ministry of Food and Drug Safety (MFDS) standards in Korea, and the rules on the installation and operation of special medical equipment in Korea. As a result of the study, six basic safety evaluation criteria related to electrical and mechanical radiation safety (leakage current, collision protection, emergency stopping device, overheating, recovery management, and ingress of water or particulate matter into medical electrical (ME) equipment and ME systems: footswitches) and 14 essential performance evaluation criteria (accuracy of tube voltage, accuracy of tube current, accuracy of loading time, accuracy of current time product, reproducibility of radiation output, linearity and consistency in radiography, half layer value in X-ray equipment, focal size and collimator, relationship between X-ray field and image reception area, consistency of light irradiation versus X-ray irradiation, performance of the mechanical device, focal spot to skin distance accuracy, image quality evaluation, and technical characteristic of cone-beam computed tomography) were selected for a total of 20 criteria.

Removal Potential of Particulate Matter of 12 Woody Plant Species for Landscape Planting

  • Kwon, Kei-Jung;Urrintuya, Odsuren;Kim, Sang-Yong;Yang, Jong-Cheol;Sung, Jung-Won;Park, Bong-Ju
    • Journal of People, Plants, and Environment
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    • v.23 no.6
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    • pp.647-654
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    • 2020
  • Background and objective: Particulate matter (PM) is one of the serious environmental problems and threatens human health. Plants can clean the air by removing PM from the atmosphere. This study was carried out to investigate the PM removal efficiency of 12 species of woody plants. Methods: Actinidia arguta, Dendropanax morbiferus, Fraxinus rhynchophylla, Parthenocissus tricuspidata, Pittosporum tobira, Rhaphiolepis indica, Rhapis, Salix integra, Salix koreensis, Schisandra chinensis, Viburnum odoratissimum var. awabuki, and Vitis coignetiae were used as plant material. Six 15 cm (D) pots were placed in an acrylic chamber of 800 (D) × 800 (W) × 1000 (H) mm. The LED panel was used as a light source. The reduction of PM10, PM2.5, and PM1 for 300 minutes after the injection of PM was automatically measured. Results: The leaf area and the amount of PM in the chamber showed a negative correlation. 12 species of plants were compared by dividing the plants into 3 groups according to their characteristics: vines, trees, and shrubs and small trees. In the vine plant group, the averages of PM10, PM2.5, and PM1 were 7.917%, 8.796%, and 30.275%, respectively. In the shrubs and small trees group, the average of PM10, PM2.5, and PM1 were 10.142%, 11.133%, and 36.448%, respectively. In the trees group, the average of PM10, PM2.5, and PM1 were 11.475%, 12.892%, and 40.421%, respectively. When the initial concentration was 100%, PM10, PM2.5, and PM1 of Viburnum odoratissimum var. awabuki with the largest leaf area were 5.6%, 6.3%, and 21.0% after 5 hours, respectively, the best results among 12 species of plants. Conclusion: The vine plant group was more effective in removing PM than the other two groups. In the tree groups, the fact that the leaf development was relatively inactive at a plant height of 30 cm was considered to have an effect on the removal of particulate matter.

Suppression of Moiré Fringes Using Hollow Glass Microspheres for LED Screen (중공 미소 유리구를 이용한 LED 스크린 모아레 억제)

  • Songeun Hong;Jeongpil Na;Mose Jung;Gieun Kim;Jongwoon Park
    • Journal of the Semiconductor & Display Technology
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    • v.22 no.3
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    • pp.28-35
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    • 2023
  • Moiré patterns emerge due to the interference between the non-emission area of the LED screen and the grid line in an image sensor of a video recording device when taking a video in the presence of the LED screen. To reduce the moiré intensity, we have fabricated an anti-moiré filter using hollow glass microspheres (HGMs) by slot-die coating. The LED screen has a large non-emission area because of a large pitch (distance between LED chips), causing more severe moiré phenomenon, compared with a display panel having a very narrow black matrix (BM). It is shown that HGMs diffuse light in such a way that the periodicity of the screen is broken and thus the moiré intensity weakens. To quantitatively analyze its moiré suppression capability, we have calculated the spatial frequencies of the moiré fringes using fast Fourier transform. It is addressed that the moiré phenomenon is suppressed and thus the amplitude of each discrete spatial frequency term is reduced as the HGM concentration is increased. Using the filter with the HGM concentration of 9 wt%, the moiré fringes appeared depending sensitively on the distance between the LED screen and the camera are almost completely removed and the visibility of a nature image is enhanced at a sacrifice of luminance.

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Process window of simultaneous transfer and bonding materials using laser-assisted bonding for mini- and micro-LED display panel packaging

  • Yong-Sung Eom;Gwang-Mun Choi;Ki-Seok Jang;Jiho Joo;Chan-mi Lee;Jin-Hyuk Oh;Seok-Hwan Moon;Kwang-Seong Choi
    • ETRI Journal
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    • v.46 no.2
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    • pp.347-359
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    • 2024
  • A simultaneous transfer and bonding (SITRAB) process using areal laser irradiation is introduced for high-yield and cost-effective production of mini- or micro-light-emitting diode (LED) display panels. SITRAB materials are special epoxy-based solvent-free pastes. Three types of pot life are studied to obtain a convenient SITRAB process: Room temperature pot life (RPL), stage pot life (SPL), and laser pot life (LPL). In this study, the RPL was found to be 1.2 times the starting viscosity at 25℃, and the SPL was defined as the time the solder can be wetted by the SITRAB paste at given stage temperatures of 80℃, 90℃, and 100℃. The LPL, on the other hand, was referred to as the number of areal laser irradiations for the tiling process for red, green, and blue LEDs at the given stage temperatures. The process windows of SPL and LPL were identified based on their critical time and conversion requirements for good solder wetting. The measured RPL and SPL at the stage temperature of 80℃ were 6 days and 8 h, respectively, and the LPL was more than six at these stage temperatures.