• Transactions on Electrical and Electronic Materials
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• v.17 no.3
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• pp.178-181
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• 2016

In this study a coating experiment was performed to fabricate blue light cut films, which represent a 390~430 nm cut off rate of more than 40% and a transmittance rate of more than 90%, using a roll-to-roll nano micro coating system. The study also analyzed the characteristics of the blue light cut films. Thus, the hardness, which is more than 3H, is ensured through fabricating films using a Sol-Gel process that will determine the proper hardness level. Also, the experiment shows excellent results by cutting blue light through a mixing blue light powder.

• Journal of Welding and Joining
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• v.14 no.5
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• pp.113-121
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• 1996

The arc sensor has been most widely used for weld seam tracking through welding current or voltage variation. In this work, the relation between the arc light intensity and welding condition is investigated using heat balance in the Plasma for its possible application to seam tracking in the GMAW process. The arc light intensity is derived to be the function of the arc length and welding current Experiments are carried out to verify the proposed heat balance model. Performances of least square and integration methods to process the signals for seam tracking are compared experimentally. Predicted arc light intensity shows reasonably good agreement with experimental results. The weld seam is successfully tracked through the arc light intensity. The least square and integration methods demonstrate almost same performance of seam tracking with $CO_2$gas shielding.

• Proceedings of the IEEK Conference
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• 2002.07c
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• pp.1398-1400
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• 2002

A new PLF-BLU (Plastic Light Fiber-Back Light Unit) using side glowing light fiber rods array for the 42" LCD TV display has been evelopedd. The light fibers were 14mm in diameter and 50cm long pure transparent acrylic rods of 1.49 refractive index. Fine seratees were made on the flat side of rod. extremely bright incandscent light from lamp fed into the fiber si scattered at scratches then emerges through the surface of rod. A typical PLF-BLU system consists of 24 PLFs produced side glow of brightness of 4,500cd/㎡ to 6,500cd/㎡. New PLF-BLU is proved to be a BLU of rigid, bright, no heat generation, and low power consumption, hence a prospective BLU system for very and/or ultra large size TVs. A new LED-PLF-BLU system considered to be a revolutionary to break-through of the BLU technologies has also been developed, and is decribed briefly.

• Journal of the Semiconductor & Display Technology
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• v.17 no.4
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• pp.6-10
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• 2018

Organic light emitting devices have attracted the attention of many people because of their high potential for self-emission and flexible display devices. However, due to limitations in device efficiency and lifetime, partial commercialization is underway. In this paper, we have investigated the electrical conduction mechanism of the organic light emitting device by the temperature and the thickness of the light emitting layer through the current - voltage characteristics with respect to the conduction mechanism directly affecting the efficiency and lifetime of the organic light emitting device. Through the study, it was found that the conduction in the low electric field region is caused by the movement of the heat excited charge in the ohmic region and the tunneling of the electric charge due to the high electric field in the high electric field region.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.23 no.1
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• pp.64-68
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• 2014

This paper introduces the use of a crown-shaped (CR) lens to effectively diffuse the light from a light-emitting diode (LED) without any loss in the light intensity, in contrast to polymer-bulb-type diffusers. The diffusion lens was designed based on the Snell's law, which describes the physical path of a ray passing through the boundary between different media. CR lenses were fabricated by polydimethylsiloxane (PDMS) casting and UV-embossing processes, which used a pre-designed metal mold and UV-curable resin, respectively. Through experiments and optical evaluations, it was verified that the newly proposed CR lens not only decreased the vertical light strength and glare effect from an LED light source but also improved the diffusion characteristics while maintaining the quality of the LED's light intensity.

• Journal of the Korean Solar Energy Society
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• v.33 no.1
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• pp.89-95
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• 2013

A DBLP(Double blind light pipe) daylight system can be installed at a building exterior wall or roof to replace artificial light during the day time. This system was consisted of a double blind light collector, a mirror duct type light transformer and a prism light pipe distributor. The double blinds were used to track the sun's altitude and azimuth movements to collect the sunlight throughout the day. The sunlight collected by the light collector was reflected on the first mirror and the second mirror and sent to the light pipe through the light transformer. The transformer was designed to deliver the sunlight into the light pipe efficiently. The light distributor plays a role in diffusing the sunlight coming in through the light collector to be used for indoor lighting. In this paper, a DBLP system has been designed, installed and tested at a KIER daylighting twin test cell. The DBLP daylighting system was applied to the experimental test cell which has an indoor area of 2.0 m wide ${\times}$ 2.4 m height ${\times}$ 3.8 m length. The experiment was conducted from January 30 to February 27, 2012, under clear skies and partially cloudy skies. Data was collected from 10:00 am to 16:00 pm every 2 minute and the average was calculated for every 30 minute of the data collection to obtain the system efficiency. The results indicated that the DBLP system efficiency was evaluated as 11.67%. The DBLP system indoor illumination energy reduction was predicted as 0.822 kWh/day. This could replace 4 sets of a 32W fluorescent lamp operating 6.4 hours per a day.

• Journal of Sensor Science and Technology
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• v.22 no.3
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• pp.212-218
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• 2013

In this paper, we introduce a new method to reduce the inter-channel crosstalk in visible light communication (VLC) systems using the synchronizing pulses transmitted through the power lines. Synchronizing pulses are simultaneously transmitted to multiple VLC transmitters and receivers through the 220V power line. Each VLC transmitter modulates an LED and each VLC receiver demodulates the signal light in the time slot that is allocated with reference to the synchronizing pulses. This method is very simple and effective to prevent the inter-channel crosstalk in VLC systems for sensor networks because every VLC system can easily get the synchronizing pulses from the nearby power line.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.26 no.4
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• pp.181-192
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• 2014

Light-shelf is one of the most efficient natural lighting systems due to the improved function of the inflow level of the outdoor natural light. However, the existing research on the light shelf limits to the rectangular parallelepiped space, so do not provide sufficient data for various shapes of spaces. Thus, this study aims at deriving proper plan and relationship of the light shelf through its performance assessment depending on the indoor space shapes and utilizing them as basic data of light shelf design. The conclusions are as follows : 1) for 6m space depth, standard intensity of illumination satisfaction depth has shown 8.3%~26.3% improvement through the adjustment of the angle and width when installing light shelf compared to no light shelf installation; 2) $-30^{\circ}$, $-20^{\circ}$ and $-10^{\circ}$ light shelves set by this study play only as a blind regardless of the shape of ceiling on the summer solstice, and it is unsuitable; and 3) this study has derived proper plan of light shelf upon space shapes based on energy reduction and indoor evenness. The study results provide expanded data of the performance assessment of the light shelves according to the different space shapes and light shelf factors, which serves as a basis of the light shelves designing.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.27 no.10
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• pp.1-8
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• 2013

Wireless Visible Light Communication is the technology that enables communication using LED illumination Infrastructure instead of existing illumination such as incandescent lamp or fluorescent light. Because VLC uses light for communication, it has no problem of frequency permission and is harmless to human body. It is also possible to check the communication through eye. So VLC can be used as a supplement to the Radio Frequency communication, Infrared in indoor environment. So far, researchers on the LED Visible light communication have focused on the increasing transmission speed, transmission distance, modulation method. However, there is few research of main factors that influence on system performance. System performance has been mainly predicted through simulation. In this paper, I recognized that these factors such as outside light noise, obstacle, LED panel position or emitted angle have a great impact on wireless communication system. So I experimented VLC system by changing distance and position to discover location suitable for BER regulation.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2017.05a
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• pp.738-740
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• 2017

Visible light communication is a communication method using light, and it has advantage of ensuring security in a single space as compared with RF communication. However, in the area outside the visible line of the light, communication disconnection occurs. Therefore, this paper proposes a relay module to overcome the coverage extension and communication disconnection phenomenon of visible light communication. The proposed relay module transmits and receives data of visible light communication by sequentially transmitting data packets including target ID through adjacent visible light module. Through experimentation of data transmission, we confirmed the extension of the transmission range and the data reception in the area outside the line of sight.