• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.921-924
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• 2008

We investigated new deep blue emitting materials including a novel side group such as CB-203. CB-203 shows relatively 40% increased PL quantum efficiency and higher Tg of $30^{\circ}C$ compared to MADN. It exhibits high External Quantum Efficiency (EQE) of 7.18% that is two times bigger than MADN's, which is the best efficiency in case of non-doped blue fluorescence OLED device to our knowledge. And deep blue emitting materials with a new core structure (CB-301) have been synthesized. CB-301 exhibit excellent blue fluorescence properties. Undoped OLED devices using CB-301 as blue emitters was found to deep blue CIE value (0.154, 0.078) and exhibit high luminance efficiencies of 2.01cd/A at $10\;mA/cm^2$.

• Journal of IKEEE
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• v.26 no.2
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• pp.205-210
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• 2022

We demonstrated roll-to-roll microcontact printed (mCP) microlens array (MLA) to enhance the light extraction of organic light emitting diodes (OLEDs). The commercially provided microlens array is used as a template for polydimethylsiloxane (PDMS) roll stamp. The fluorinated film is formed on the PDMS roll stamp from fluorinated ink with low boiling point and printed onto the bottom side of the organic light emitting diode without high pressure and high thermal treatment. With optimized concentration of ink, the pattern which is almost identical to that of the template MLA was successfully printed. Due to the structure and low optical absorbance of microcontact printed MLA, the external quantum efficiency of OLED was improved by about 18%.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.940-941
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• 2015

LCD (liquid crystal display) industry is needed to goods of high reliability and is interested in products without harmful material. In this experiment, we made the LED backlight unit for Automotive-navigation. And for making this backlight unit we used to eight side emitting type white LEDs with 1W high power of the lumileds company. We could know that this backlight unit releases to 6500 nit in 14W power consumption and start up voltage time is under the15ms in the ambient temperature $-20^{\circ}C$.

• Journal of Korea Multimedia Society
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• v.21 no.6
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• pp.705-711
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• 2018

Intravenous(IV) therapy being in use for many patients may cause serious side effects such as infiltration, extravasation. To minimize such side effects, it is important to detect symptoms appearing when fluid escapes from blood vessel to tissue as soon as possible. This paper describes a device which has been developed to detect IV infiltration early using optical sensor. The device detects IV infiltration as measuring intensity of lights reflected from that lights after emitting lights in IV therapy site. The lights are consisted of 4 different waves which provide different reflection ratio depending the fluid used in IV therapy. The experimental results show that the device can be used to detect IV infiltration early.

• Proceedings of the KIPE Conference
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• 2014.07a
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• pp.165-166
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• 2014

기존 LED(Light Emitting Diode) 전류 제어용 SSPR(Secondary Side Post Regulator) 스위치를 갖는 구조의 다중출력 컨버터는 LED 정 전류 제어를 위한 별도의 부스트 컨버터 없이 전류제어가 가능하여 원가 및 부피 저감과 효율이 상승하는 장점이 있다. 하지만, 주 출력단(Master)의 피드백을 받아 1차 측 메인 스위치를 제어하게 되어 제어 회로가 복잡하고 주 출력단 부하 변동에 의해 부 출력단(Slave)의 크로스-레귤레이션(Cross-Regulation) 특성이 좋지 않은 단점이 있다. 따라서, 본 논문에서는 기존 SSPR 스위치의 장점을 갖고 주 출력 단의 부하 변동에도 부 출력단의 크로스-레귤레이션 특성이 좋은 새로운 직렬 공진형 LED 구동회로를 제안한다. 최종적으로 제안 회로를 4채널 LED 구동회로에 적용하여 그 실험결과를 바탕으로 제안 회로의 타당성을 검증하였다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.7
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• pp.3146-3151
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• 2012

For using them as a optical source of inspections equipment for LCD panel, the design ofexcellent backlight system, brightness uniformity and high power and good protection against heat is essential.In this paper, backlight system which is built in the 45 inch side emitting LCD backlight by LED arraystructure and driving circuit were designed and developed. After that, their performances were measured. Itshowed the luminance from 3,000 to 25,000[$cd/m^2$], the mean value x:0.3144, y:0.3076 of x-y chromaticity,dimming range of 27~515[$cd/m^2$], free flicker noise in the 80kHz and black level of 0.7~0.1[$cd/m^2$], thermaltest of cooling system in 20,000[$cd/m^2$] over values.

• Korean Journal of Optics and Photonics
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• v.16 no.3
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• pp.275-286
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• 2005

The performance of the InGaN LED's in terms of the photon extraction efficiency has been analyzed by the Monte Carlo photon simulation method. Simulation results show that the sidewall slanting scheme, which works well for the AlInGaP or InGaN/SiC LED, plays a very minimal role in InGaN/sapphire LED's. In contrast to InGaN/SiC LED's, the lower refractive index sapphire substrate restricts the generated photons to enter the substrate, minimizing the chances for the photons to be deflected by the slanted sidewalls of the epitaxial semiconductor layers that are usually very thin. The limited photon transmission to the sapphire substrate also degrades the. photon extraction efficiency especially in the epitaxial-side down mount. One approach to exploit the photon extraction potential of the epitaxial-side down mount may be to texture the substrate-epitaxy interface. In this case, randomized photon deflection off the textured interface directly increases the number of the photons entering the sapphire substrate, from which they easily couple out of the chip and thereby improving the photon extraction efficiency drastically.

• Journal of the Semiconductor & Display Technology
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• v.21 no.4
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• pp.106-109
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• 2022

The green-emitting Zn₂SiO₄:Mn²⁺ phosphor film was evaluated in a xenon excimer lamp. The phosphor film with 2 ㎛ thick was formed of monolithic structure on the inner side of quartz through a long-time annealing process of coated ZnO solution doped with Mn²⁺ ion and SiO₂ of quartz tube. The coated quartz was filled with 100 torr of xenon gas, and simultaneously both sides was melt and sealed. The xenon-field quartz tube was discharge by applying the voltage of 15 kV with a frequency of 26 kHz, and emitted the glow with dominant peak at 172 nm. The vacuum ultraviolet excited the inner-side coated Zn₂SiO₄:Mn²⁺ phosphor film, which emitted the pure and strong green light.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.49 no.5
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• pp.10-15
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• 2012

In this work, we proposed the asymmetric MQW structure with gradually increased or decreased well thickness from n-layers to p-layers in order to improve the performance of DUV-LEDs. We report the simulation results of electrical/optical characteristics by using the SimuLED program. From the simulation results, we found that B structure with thickness of the wells gradually increased from the n-side to the p-side has the same forward voltage(Vf) as standard structure, but the light output power (Pout) was improved by a factor of 1.17 at 20mA compared with those of the standard structure.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.25 no.10
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• pp.1451-1458
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• 2001

The effects of a specularly reflecting surface on the wall heat flux and medium temperature distribution are studied. The system is an infinite square duct enclosing an absorbing and emitting medium. The walls are opaque, and black or gray. The walls emit diffusely but reflect diffusely or speculary. Heat is transferred by the combined effect of conduction and radiation. The radiative heat transfer is analyzed using direct discrete-ordinates method. The parameters under study are conduction, to radiation parameter, optical depth, wall emissivity, and reflection characteristics. The specular reflection and diffuse reflection show sizeable differences when the conduction to radiation parameter is less than around 0.01. The differences appear only either on the side wall heat flux or on the medium temperature profiles for the range of this study. The differences on the side wall heat flux are observed for optical thickness less than around 0.1 However the differences on the medium temperate profiles are found for optical thickness greater than around 1. The difference increase with increasing reflectance. The specular reflection increases the well heat flux gradient along the side wall.