• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.26 no.7
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• pp.1-8
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• 2012

In this paper, we improved the light extraction efficiency by structural change of LEDs on conventional LEDs. We simulated the LEDs light emission as functions of LED side wall angle, various refractive indices the geometrical structures and analyzed the condition improved the light efficiency. We present the results of experimerns and simulations for light output power from LEDs for various refractive indices and the geometrical structures of the LED encapsulants. When the side wall angle range was from 40[$^{\circ}$] to 30[$^{\circ}$], the LED emission increased. LED side wall angle onto LED using the simulation system with a fine tuning of the structure of the LEDs side wall angle is fabricated. Additionally, we changed the side wall angle of LED package with spherical structure and flat structure. The result of spherical structure ray tracting is higher compared with flat structure about 14[%].

• The Journal of the Convergence on Culture Technology
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• v.8 no.5
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• pp.713-721
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• 2022

In order to use the LED video wall in the broadcasting studio, there are a few things to be aware of. First, since the pixels are closely arranged, a moire phenomenon may occur due to a short arrangement period, and second, the distance between pixels (pixel pitch) may be recorded on the image sensor of the broadcasting camera. When moire occurs or pixel pitch is observed, viewers feel uncomfortable. Moire effect can be reduced by adjusting the shooting distance or angle of the camera, but in order to prevent the pixel pitch from being recorded on the image sensor, secure a sufficient distance between the LED video wall and camera. even when the distance secured, the zoom lens used in the broadcasting studio must be operated by appropriately changing the magnification. If the focal length is changed by changing the magnification to obtain a desired angle of view, the pixel pitch may be unintentionally recorded. In this study we propose the range that the pixel pitch is not observed while changing the magnification ratio of the zoom lens when the distance from the video wall is sufficiently secured. The content was played back on the LED video wall and the LED video wall was recorded on the server using an HD camera equipped with a B4 mount zoom lens

• Journal of the Microelectronics and Packaging Society
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• v.22 no.4
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• pp.71-76
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• 2015

Recently, light emitting diodes (LEDs) have been studied to improve their efficiencies for the uses in various fields. Particularly in the aspect of chip structure, via hole type vertical LED chip is developed for improvement of light output power, and heat dissipations. However, current vertical type LEDs have still drawback, which is current concentration around the n-contact holes. In this research, to solve this phenomenon, we introduced isolation layer under n-contact electrodes. With this sub-electrode, even though the active area was decreased by about 2.7% compared with conventional via-hole type vertical LED, we could decrease the forward voltage by 0.2 V and wall-plug efficiency was improved approximately 4.2%. This is owing to uniform current flow through the area of n-contact.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2022.11a
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• pp.222-224
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• 2022

지난 2021년, 국내 최초로 온라인 소비가 오프라인 소비를 뛰어넘을 정도로 언택트 경제가 급부상하였다. 덕분에 언택트 시장의 주도권을 가진 라이브 커머스는 무서운 속도로 성장하고 있고, 이는 적어도 2023년까지 이어질 것으로 예상된다. 중소기업은 물론 대기업, 심지어 개인까지 라이브 커머스 시장에 탑승한 현재, 라이브 커머스 시장의 경쟁력은 점차 사라지고 있다. 이로 인해 공급자들은 차별성을 두기 위해 여전히 다양한 방법을 찾아 시도하고 있다. 본 논문에서는 계속해서 수요되는 라이브 커머스 시장에서 경쟁력을 갖출 수 있는 방법으로 LED Wall의 활용을 제안한다.

• International Journal of Internet, Broadcasting and Communication
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• v.14 no.2
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• pp.10-16
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• 2022

As an important part of virtual production, In-camera VFX is the process of shooting actual objects and virtual three-dimensional backgrounds in real-time through computer graphics technology and display technology, and obtaining the final film. In the In-camera VFX process, there are currently only two types of medium used to undertake background imaging, LED wall and chroma key screen. Among them, the In-camera VFX based on LED wall realizes background imaging through LED display technology. Although the imaging quality is guaranteed, the high cost of LED wall increases the cost of virtual production. The In-camera VFX based on chroma key screen, the background imaging is realized by real-time keying technology. Although the price is low, due to the limitation of real-time keying technology and lighting conditions, the usability of the final picture is not high. The short-throw projection technology can compress the projection distance to within 1 meter and get a relatively large picture, which solves the problem of traditional projection technology that must leaving a certain space between screen and the projector, and its price is relatively cheap compared to the LED wall. Therefore, in the In-camera VFX process, short-throw projection technology can be tried to project backgrounds. This paper will analyze the principle of short-throw projection technology and the existing In-camera VFX solutions, and through the comparison experiments, propose a low-cost solution that uses short-throw projectors to project virtual backgrounds and realize the In-camera VFX process.

• Korean Journal of Optics and Photonics
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• v.30 no.4
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• pp.142-145
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• 2019

Normally, a corner cube retroreflector (CCRR) sheet is used as a retroreflective mirror array (RRMA) in a volumetric display. Each CCRR unit reflects light in the retroreflective direction, which is parallel to the incident light, and it makes a blurred image, as it shifts the position of light within its dimensions. Adopting a "curved planar wall" and "parabolic focusing" (x-axis), a hybrid-t(transverse direction)-RRMA is proposed, to improve the image quality and brightness. The improvement of image contrast is achieved by tuning a "linear v-shaped groove" structure to a "parabolic v-shaped groove". Also, the system has been simplified and the brightness enhanced 4 times by removing the half mirror.

• Proceedings of the KIEE Conference
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• 2002.11a
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• pp.197-199
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• 2002

This paper describes the effects of chip arrangement configurations and the dimension of a reflecting cup upon the light output characteristics of a white lamp composed of RGB LED chips. As a result of simulation, the shorter distance between adjacent chips leads to a relative decrease in the light output efficiency due to inter-chip absorption of quanta, but rather uniform color mixing is expected. Among the factors of designing a reflecting cup it is the tilt angle of the cup wall that plays a determining role upon the variation of the light distribution. The light distribution shows a sudden change of pattern from Lambertian to Batwing at about $35^{\circ}{\sim}40^{\circ}$ of tilt angle in case of a silver-coated wall cup.

• International journal of advanced smart convergence
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• v.11 no.2
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• pp.64-70
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• 2022

In recent years, with the continuous innovation and upgrading of engine software, the real-time rendering technology in film and television has been continuously improved, and the virtual production technology has also developed rapidly. This paper introduces the green screen often used in traditional film production and a virtual production technology based on light-emitting-diode background wall that was proposed and implemented last year. We analyzed the two production methods of virtual production and compared their characteristics. Based on these results, we can better understand the differences and respective advantages of the two production methods. And we also can according to the production budget, production cycle and the creative and technical capabilities of the team make better choices during the production process. We believe virtual production technology will be production in the future to provide a more solid technical guarantee for the development of the film industry, and this work will pave the way for further research on virtual production technology.

• Korean Journal of Optics and Photonics
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• v.35 no.1
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• pp.18-23
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• 2024

In exhibition spaces such as art museums, lighting should primarily illuminate the walls where exhibits are displayed rather than the floor. Commonly used LED lighting consists of an LED and a diffusion plate that closely resembles a Lambertian light source with uniform light distribution at every angle. This type of illumination focuses on the floor surface where normal incidence occurs. Consequently, this general illumination method is not well-suited for effectively lighting the wall surface. Specifically, to illuminate a wall, it is necessary to increase the light intensity in areas with a large incident angle in the light distribution. In response to this issue, our study proposes an illumination system that uses an ultra wide converter to adjust the divergence angle from the light source to 180 degrees.

• Journal of the Optical Society of Korea
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• v.17 no.1
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• pp.22-26
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• 2013

The author analyzes the luminous efficiency of the phosphor-conversion white light-emitting diode (LED) that consists of a blue LED chip and a yellow phosphor. A theoretical model is derived to find the relation between luminous efficiency (LE) of a white LED, wall-plug efficiency (WPE) of a blue LED chip, and the phosphor absorption ratio of blue light. The presented model enables to obtain the theoretical limit of LE and the lower bound of WPE. When the efficiency model is applied to the measured results of a phosphor-conversion white LED, the limit theoretical value of LE is obtained to be 261 lm/W. In addition, for LE of 88 lm/W at 350 mA, the lower bound of WPE in the blue LED chip is found to be ~34%. The phosphor absorption ratio of blue light was found to have an important role in optimizing the luminous efficiency and colorimetric properties of phosphor-conversion white LEDs.