Simulation study on the optical structures for improving the outcoupling efficiency of organic light-emitting diodes

정수성,고재현 한국정보디스플레이학회 2012 Journal of information display Vol.13 No.4

In this study, optical simulation was used to compare three optical structures that could be applied to the typical organic light-emitting diode to increase the outcoupling efficiency. These were spherical scattering particles (treated as Mie scatterers) embedded in the glass substrate, microlenses formed on the glass substrate, and a diffusing layer (DL) with a Gaussian scattering distribution function inserted between the indium tin oxide (ITO) and the glass substrate. It was found that the application of microlens array and that of scattering particles in the glass substrate exhibited similar enhancements in the outcoupling efficiency when the density and the refractive index of the scattering particles were optimized. The DL located at the interface between the glass and the ITO further enhanced the efficiency because it could further extract the trapped light in the waveguide mode. The appropriate combination of these three structures increased the outcoupling efficiency to about 42%, which is much greater than the typical values of 15–20% when there is no optical structure for light extraction.

포상기태임신의 골반내 감돈 1례

정수성,이성호,신용철,이희동 대한산부인과학회 1978 대한산부인과학회 학술대회 Vol.41 No.-

충남 농촌지역의 난관불임술 보급실태에 관한 연구

정수성,류우국,남상윤,강길전 대한산부인과학회 1984 대한산부인과학회 학술대회 Vol.53 No.-

Optical Simulation Study on the Effect of Diffusing Substrate and Pillow Lenses on the Outcoupling Efficiency of Organic Light Emitting Diodes

정수성,고재현 한국광학회 2013 Current Optics and Photonics Vol.17 No.3

The effect of diffusing substrate and pillow lenses on the outcoupling efficiency of organic light-emitting diodes (OLEDs) was studied by optical simulation based on the point-dipole model. The diffusing substrate included Mie scatterers by which the condition of total internal reflection could be broken. The finite-difference time-domain method was used to obtain the intensity distribution on the transparent electrode of an OLED, which was used as a light source to carry out a ray-tracing simulation of the OLED and the diffusing substrate. It was found that the outcoupling efficiency of the OLED was sensitive to the thickness of organic layers and could be increased by 21.0% by adopting a diffusing substrate in which Mie scatterers whose radius was 2.0 μm were included at the density of 107 mm-3 and by 65.5% by forming one pillow lens with the radius of 2 mm on the front surface of the glass substrate. This study revealed that the outcoupling efficiency could be improved by adopting diffusing substrate and pillow lenses along with the optimization of the thickness of each layer in the OLED.

나르시서스를 고려한 냉각형 적외선 광학계 설계

정수성,김영수,홍진석,이경묵,윤지연 한국광학회 2019 한국광학회지 Vol.30 No.6

In an infrared optical system, using a cooled detector generates a phenomenon called a narcissus, in which the focal-plane array (FPA) cooled by very low temperatures is reflected in the lens surface and detected. The narcissus can be removed by nonuniform correction (NUC) of the detector pixel, so narcissus is generally ignored by infrared optics. However, nonuniformity correction reduces the sensitivity of the system. Also, as housing temperatures differs due to environmental temperature change, or a lens is moved for focus or athermalization purposes, a narcissus may occur even after non-uniformity correction. To minimize such a narcissus, the amount of the effect must be controlled in the lens-design stage. In this paper we designed a midinfrared optical system and analyzed the narcissus by setting the lens surface reflectance to 1%. In addition, the design was divided into stages of an initial design, an improved design, and a minimum design, and the narcissus was improved to about 56% of that in the initial design.

Analysis of the spectral characteristics of white light-emitting diodes under various thermal environments

정수성,고재현 한국정보디스플레이학회 2012 Journal of information display Vol.13 No.1

An empirical functional form was suggested for the analysis of the emission spectrum of high-power light-emitting diode (LED) consisting of a sharp blue peak fromtheLEDchips and a broad yellow peak fromthe phosphor layer. The peak positions,half widths, shape parameters, and amplitudes of these two peaks were reliably obtained as a function of the temperature, and the results were discussed qualitatively in relation with the junction temperature. The adoption of an inert liquid was found to have significantly reduced the LED temperature and the color shift of the emitted light. The phenomenological approach used in this study may be helpful in the simulation of the LED spectrum under various thermal conditions, and may thus be helpful in the improvement of the device performance.

Far-field luminous intensity distribution depending on the outcoupling structure of organic light-emitting diodes

정수성,고재현 한국정보디스플레이학회 2013 Journal of information display Vol.14 No.2

The finite-difference time domain method was combined with the ray tracing technique to investigate the viewing angle characteristics of organic light-emitting diodes (OLEDs) with various optical structures for improving the outcoupling efficiency. The angular dependence of the far-field luminous intensity on OLEDs with a basic structure and on the one with scattering particles in the glass substrate exhibited an almost Lambertian distribution at their optimized conditions. The pillow lenses applied onto the front surface of the glass substrate made the intensity distribution complex with local-intensity maxima appear. This was attributed to the interactions between the curved lens surfaces and the rays emitted from the light source. This study suggests that both the microcavity in the organic layers and the optical structure for efficient outcoupling should be optimized to realize appropriate viewing angle characteristics for display or lighting applications.

국내 2G-3G간 로밍 구현방안과 해결과제

정수성 한국기술사회 2001 技術士 Vol.34 No.5

The national 2G-3G roaming is emerging as one of essential and important issues In Korea in connection with the recent granting of 3G licenses. Accustomed to the current seamless coverage and superb quality of 2G networks, many subscribers have very high expectations of an equal or better service provisioning by 3G networks. However, it is very unlikely for 3G operators to successfully build their networks as comprehensive as the current 2G networks in the beginning of network implementation and commercial launch. Therefore,3G operators are seriously considering the national 2G-3G roaming in Korea. In this paper. 1 would like to discuss and present a technical implementation scheme and problems that need to be solved fer successfully realizing the national 2G-3G roaming.

광결정 구조가 적용된 유기발광다이오드의 광추출효율 및 광도 분포에 대한 시뮬레이션 연구

정수성,최현우,고재현 한국물리학회 2013 새물리 Vol.63 No.8

유한차분 시간영역 방법과 광선 추적 시뮬레이션에 기반해서 광결정이적용된 유기발광다이오드(OLED)의 광추출효율 및 광도 분포를 조사했다. 굴절률이 1.9인 SiN으로 형성된 원통형 광결정을 투명전극과 유리 기판사이에 500 nm 주기의 정사각형 격자 형태로 배치한 후 반지름과 높이를최적화한 결과 OLED의 광추출효율이 약 1.3 배 향상될 수 있음을확인하였다. 유리 기판에 산란입자를 포함시켜 기판 모드에 대한추가적인 추출을 시도한 결과 광추출효율은 약 1.46 배 증가하였다. OLED 소자로부터 출광되는 빛의 광도 분포는 광결정의 격자구조가 가지는 4축회전 대칭성을 띠고 있음이 확인되었고 이러한 시야각 특성은 유리기판에 포함되는 산란 입자의 밀도를 증가시킴에 의해 완화되고 람버시안분포에 가까워질 수 있음을 확인하였다. The outcoupling efficiency (OCE) and the intensity distribution for photonic crystal-based organic light-emitting diodes (OLEDs) were investigated by using the finite difference time domain method and a ray tracing optical simulation. The OCE increased by a factor of 1.3 when optimized cylindrical photonic crystals, where refractive index was set to 1.9, were formed as a square lattice between the transparent electrode layer and the substrate. The inclusion of scattering particles in the substrate was effective in extracting the substrate mode, by which the OCE could be enhanced by a factor of 1.46. The intensity distribution from the photonic crystal-based OLEDs exhibited a four-fold rotational symmetry, which reflected the symmetry of the square lattice structure of the photonic crystals. This peculiar intensity distribution approached the Lambertian distribution as the density of the scattering particles included in the glass substrate was increased.

子宮破裂의 臨床的 考察 : A Clinical Analysis of 23 Cases

鄭首成,李熙東 충남대학교 의과대학 지역사회의학연구소 1979 충남의대잡지 Vol.6 No.1

A clinical analysis of 23 cases of the uterine rupture observed at Chungnam National University Hospital from July 1974 to February 1979 was made. The results are summerized as follows; 1. The incidence of uterine rupture was 1 to 94 deliveries. 2. Most of the cases(16 of 23 cases) were of parity 3 or more. 3. Types of the rupture were traumatic(12 cases), spontaneous of the intact uterus (8 cases) and previous cesarean section scar rupture (3 cases). All occurred during labor. 4. The mean gestational duration was 39.4 wks. 5. Most of the ruptures(15 of 23 cases) occurred at home delivery with or without midwife. 6. Site of the rupture was mostly(20 of 23 cases) lower uterine segment. 7. The maternal death occurred in one case (4.4%) and perinatal death occurred in 21 cases(91. 3%). 8. Types of management were total hysterectomy(14 cases), subtotal hysterectomy (8 cases) and in one case debridement & simple suture was done.