• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.25 no.9
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• pp.755-758
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• 2012

We developed a new solar simulator to evaluate a large-scale solar cell using seven kinds of LEDs (Infrared, Red, Yellow, Green, Blue, White and Ultra Violet LED). LED solar simulator can be displaced the existing solar simulator which has several demerits such as high power consumption and short lifetime. We have tried to fabricate LED solar simulator which fulfills the spectrum for AM 1.5G condition, and to verify the feasibility of LED solar simulator.

• Korean Journal of Optics and Photonics
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• v.21 no.2
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• pp.61-68
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• 2010

Optical simulation methods were applied to the edge-lit LED backlight for LCD TV applications in order to optimize the optical structure of the light guide plate(LGP), and thus to improve the uniformity properties by removing the bright spots caused by LED's. The edge-lit LED backlight consisted of three white LED's with a lamp cover, a light guide plate, and a reflection film. When there was no pattern on the entrance side surface of the LGP, the illuminance uniformity was sensitively dependent on the distance d between the LED and the entrance surface. The illuminance uniformity increased with d but its increasing rate slowed down when d was beyond ~ 1.5 mm. When micro-patterns such as a lenticular lens array (LLA) or a serration pattern were formed on the entrance surface, the illuminance uniformity was improved substantially even for the case of very small d. At the same simulation condition, the lightguide with serration pattern showed a better uniformity than that with LLA pattern. Additional improvement could be achieved by changing the refractive index of the micro-patterns. These results suggest that using micro-patterns is a very effective way to reduce the bright spots due to their refracting function for the concentrated incident rays onto the LGP.

• Proceedings of the Technology Innovation Conference
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• 1996.12a
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• pp.154-178
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• 1996

This paper applies the technology-gap trade theory to explaining radical changes in the competitive positions of countries in world machine tool markets over the last three decades. It develops the notion that the innovation gaps in machine tools among countries led to the inter-country differences in the competitive performance in the sector as well as in its user sectors. Since competitive advantage largely depends on a capability to improve, create and apply technology to market competition, a higher innovative performance in one country than another is closely related to a higher innovative performance. A higher innovative performance in machine tools is also associated with a higher competitive performance of the large areas of its user sectors, due to sectoral interdependences and externalities generated by machine tool innovations. The results of empirical investigation through a panel data analysis show that the international gaps in machine tool innovations appeared to have a positive significant relationship with the differences in the export performance of both the machine tool sector and its user sector across countries.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.31-34
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• 2009

We investigated the effect of relative dielectric constant of front dielectric layer on the efficacy of plasma display panel. Dielectric materials with relative dielectric constant of around 6 and 7 were developed. When the front dielectric layer had a low relative dielectric constant, power consumption decreased more than luminance did. And it led to efficacy enhancement. However, the minimum sustain voltage increased.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.474-475
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• 2009

As a substitute of ITO material, carbon nanotube (CNT) is widely studied for transparent conductive film (TCF). Current sheet resistance of CNT-TCF is about 100 ${\Omega}$/sq at 80% transmittance. But CNT-TCF performance in manufacturable level is about 500 ${\Omega}$/sq at 83% based on the Topnanosys Co's result. Therefore, critical issue in CNT-TCF research is to reduce the sheet resistance with manufacturing reliability. In this report, recent developments using CNT-TCF are introduced. Touch panel, transparent LED signboard, transparent speaker and transparent heater are representative examples. Also I describe the future issues and prospect of CNT-TCF for the flexible display.

• Electronics and Telecommunications Trends
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• v.34 no.2
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• pp.10-18
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• 2019

Since the introduction of CRT(Cathode Ray Tube) in the 1950s, display technologies have been developed continuously. Flat panel displays such as PDP(Plasma Display Panel) and LCD(Liquid Crystal Display) were commercialized in the late 1990s, and OLED(Organic Light Emitting Diodes) and Micro-LED(Micro-Light Emitting Diodes) are now being developed and are becoming widespread. In the future, we expect to develop ultra-realistic, flexible, embedded sensor displays. Ultra-realistic display can be applied to AR/VR(Augmented Reality/Virtual Reality) devices and spatial light modulators for holography. The sensor-embedded display can be applied to robots; electronic skin; and security devices, including iris recognition sensors, fingerprint recognition sensors, and tactile sensors. AR/VR technology must be developed to meet technical requirements such as viewing angle, resolution, and refresh rate. Holography requires optical modulation technology that can significantly improve resolution, viewing angle, and modulation method to enable wide-view and high-quality hologram stereoscopic images. For electronic skin, stable mass production technology, large-area arrays, and system integration technologies should be developed.

• Journal of Environmental Science International
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• v.22 no.9
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• pp.1171-1180
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• 2013

Recent climate change has led to fluctuations in agricultural production, and as a result national food supply has become an important strategic factor in economic policy. As such, in this study, panel data was collected to analyze the effects of seven meteorological elements and using the Lagrange multipliers method, the fixed-effects model for the production of five types of food crop and the seven meteorological elements were analyzed. Results showed that the key factors effecting increases in production of rice grains were average temperature, average relative humidity and average ground surface temperature, while wheat and barley were found to have positive correlations with average temperature and average humidity. The implications of this study are as follow. First, it was confirmed that the meteorological elements have profound effects on the production of food crops. Second, when compared to existing studies, the study was not limited to one food crop but encompassed all five types, and went beyond other studies that were limited to temperature and rainfall to include various meterological elements.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.10a
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• pp.535-538
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• 2005

The purpose of this work is to study a process organization on space cognition by visio-auditory stimulation. We develop the system of visuo-auditory stimulation and Humans responses measurement to observe the relationship between the sensory and the motor system fur the localization of visual and auditory target direction in the space. The experiments is performed in a soundproof chamber, 2163 red, green and yellow LED(Luminescent Diode, Brightness: $20cd/m^2$ 1 degree apart each other)arrayed in front of half-circle panel were used and 57 Speaker(5 degree apart each other) arrayed in the hidden of half-circle panel. Physiological parameters such as EOG (Electro-Oculography), head movement and their synergic control are measured by BIOPAC system and Optotrak Certus. This result shows that the response latency time of the perception motion in the center is laster than the periphery of panel. These results can be used in the study of characterizing the spatial cognition.

• 전자공학회논문지 IE
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• v.48 no.4
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• pp.25-29
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• 2011

Organic electroluminesencent device have been studied because of its easy fabrication and high brightness for plate panel display instead of CRT and LED. There are some device structure for full color filter system can be applicable to the full color application if the blue light organic electroluminesencent device(OELD) is developed. In this study, We have investigated electro-luminescent (EL) characteristics of organic EL device using Alq3, PBD as emitting material. Current and luminance can be seen that express a similar relativity in voltage and could know that luminance is expressing current relativity.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07b
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• pp.1046-1049
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• 2005

We have developed polymer LED displays using ink jet printing without visible swathe marks which can be observed during display operation. In addition, we have also developed a single-pass printing technology for hole-conduction layer deposition to significantly reduce the complexity of interlacing printing across the panel which is known as an alternative to remove the swathe mark.