• 한국광학회:학술대회논문집
• /
• 한국광학회 2007년도 하계학술발표회 논문집
• /
• pp.289-290
• /
• 2007

We have theoretically derived a electrical model and extracted a parasitic parameters of leakage current in InGaN/GaN light emitting diodes (LEDs). The parasitic parameters of our LED are $R_p=10^{10}{\Omega}$, $I_{0,2}=10^{-17}A$ and $n_2=3.6$, which provide information of leakage current.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2006년도 제31회 학술논문발표회 초록집
• /
• pp.137-137
• /
• 2006

• 한국실내디자인학회논문집
• /
• 제16권2호
• /
• pp.115-122
• /
• 2007

The purpose of this study is to extract design concepts, especially in relation to light, as a part of extracting design concepts in architectural interior design. This study consists of two steps. Firstly, appropriate design concepts are extracted from various design characteristics. Secondly, these concepts are classified in the frame of other components of architectural space, as well as in the frame of the plastic characteristics of light. Various design characteristics were analyzed, those of which relating to the plastic character of space, namely, visual phenomenon. As a result of the analysis, 32 concepts were extracted. These concepts, in the frame of other components of architectural space (space, form, structure, opening of space, material, color, inside & outside relationship), were classified, as well as In the frame of the plastic character of Light (transparency, perception, direction, ornament). As the results of this research, the suggested design concepts will be a study material, available to the interior designers as well as students who want to utilize the organized study concepts.

• JSTS:Journal of Semiconductor Technology and Science
• /
• 제15권4호
• /
• pp.454-461
• /
• 2015

Light enhancement of GaN based light emitting diodes (LEDs) have been investigated by texturing the top p-GaN surface. Nano-textured LEDs have been fabricated using self-assembled Ni nano mask during dry etching process. Experimental results were further compared with simulation data. Three types of LEDs were fabricated: Conventional (planar LED), Surface nano-porous (porous LED) and Surface nano-cluster (cluster LED). Compared to planar LED there were about 100% and 54% enhancement of light output power for porous and cluster LED respectively at an injection current of 20 mA. Moreover, simulation result showed consistency with experimental result. The increased probability of light scattering at the nano-textured GaN-air interface is the major reason for increasing the light extraction efficiency.

• 조명전기설비학회논문지
• /
• 제26권7호
• /
• pp.1-8
• /
• 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[%].

• 멤브레인
• /
• 제8권3호
• /
• pp.138-147
• /
• 1998

접촉분해 경유에 함유된 유용 방향족 성분(나프탈렌류 성분:탄소수 10-12)의 분리법으로서 추출법과 액막법을 분리성능 면에서 비교했다. 추출법의 용매로서는 dimethylsulfoxide수용액을, 액막법의 막상으로서는 dimethylsulfoxide와 saponin의 혼합수용액을 각각 사용했다. 추출법에서 얻어진 노르말-노난을 기준 성분으로한 나프탈렌류 성분의 선택도는 온도가 낮아짐에 따라 급격히 증가했으나, 액막법에서 얻어진 선택도는 온도에 무관한 경향을 나타내어, 실온에서의 추출법에 의한 나프탈렌류 성분의 선택도는 액막법에서 얻어진 선택도는 온도에 무관한 경향을 나타내어, 실온에서의 추출법에 의한 나프탈렌류 성분의 선택도는 액막법에 비해 컸다. 또, 회분 교반조를 사용하여 두 분리법으로 부터 나프탈렌류 성분의 물질이동속도를 측정한 결과, 추출법의 연속상측 물질이동계수는 액막법의 막상측 투과계수에 비해 약 280배 컸다.

• Journal of Information Display
• /
• 제13권4호
• /
• pp.139-143
• /
• 2012

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.

• Journal of the Optical Society of Korea
• /
• 제18권3호
• /
• pp.283-287
• /
• 2014

Square lattice nano-hole arrays with diameters and periodicities of 200 and 500 nm, respectively, are fabricated on InGaN/GaN blue light emitting diodes (LEDs) using electron-beam lithography and inductively coupled plasma reactive ion etching processes. Cathodoluminescence (CL) investigations show that light emission intensity from the LEDs with the nano-hole arrays is enhanced compared to that from the planar sample. The CL intensity enhancement factor decreases when the nano-holes penetrate into the multiple quantum wells (MQWs) due to the plasma-induced damage and the residues. Wet chemical treatment using KOH solution is found to be an effective method for light extraction from the nano-patterned LEDs, especially, when the nano-holes penetrate into the MQWs. About 4-fold CL intensity enhancement factor is achieved by the KOH treatments after the dry etching for the sample with a 250-nm deep nano-hole array.

• 제어로봇시스템학회논문지
• /
• 제22권10호
• /
• pp.811-816
• /
• 2016

In light of recently developed 3D printers for rapid prototyping, there is increasing attention on the 3D scanner as a 3D data acquisition system for an existing object. This paper presents a prototypical 3D scanner based on a striped laser light image. In order to solve the problem of shadowy areas, the proposed 3D scanner has two cameras with one laser light source. By using a horizontal rotation table and a rotational arm rotating about the latitudinal axis, the scanner is able to scan in all directions. To remove an additional optical filter for laser light pixel extraction of an image, we have adopted a differential image method with laser light modulation. Experimental results show that the scanner's 3D data acquisition performance exhibited less than 0.2 mm of measurement error. Therefore, this scanner has proven that it is possible to reconstruct an object's 3D surface from point cloud data using a 3D scanner, enabling reproduction of the object using a commercially available 3D printer.

• Journal of Information Processing Systems
• /
• 제19권4호
• /
• pp.483-497
• /
• 2023

Depth estimation is one of the most complicated and difficult problems to deal with in the light field. In this paper, a compound attention convolutional neural network (CAttNet) is proposed to extract depth maps from light field images. To make more effective use of the sub-aperture images (SAIs) of light field and reduce the redundancy in SAIs, we use a compound attention mechanism to weigh the channel and space of the feature map after extracting the primary features, so it can more efficiently select the required view and the important area within the view. We modified various layers of feature extraction to make it more efficient and useful to extract features without adding parameters. By exploring the characteristics of light field, we increased the network depth and optimized the network structure to reduce the adverse impact of this change. CAttNet can efficiently utilize different SAIs correlations and features to generate a high-quality light field depth map. The experimental results show that CAttNet has advantages in both accuracy and time.