• The Journal of the Korea Contents Association
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• v.8 no.11
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• pp.154-161
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• 2008

Rapidly changing 3D rendering technology is expanding its fields of display fast towards Non-Photorealistic Rendering beyond Photorealistic Rendering. It is now attainable to realize conventional 2D visual animated cartoons with 3D animation technology. It is not complex to create two shades of color or more with the rendered outcomes, made by Toon-Shading, of 3D total packaging animation Maya with black outlines brought through the process of 2D animation. It the reality of 3D animation being one of the prevalent mechanisms of animated films, it is valuable for familiarized animated cartoons to be realized by the technology of 3D animation. Thus, I hope to help in many ways create more effective 3D cartoon animation production process by optimized Toon-Shading attributes method and technology in this research.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.5
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• pp.474-480
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• 2008

In order to make full color cholesteric displays, color filter-less R, G, B sub-pixel structured cholesteric LC cells have been studied. To make R, G, B colors, UV induced pitch variant chiral dopant was added to cholesteric LC mixtures. The concentration of the photo-sensitive chiral dopant was adjusted so that the initial state showed blue color and the color was changed from blue to green and red with increase of UV irradiation to the cholesteric cells. To prevent the mixing of R, G, B reflective sub-pixel liquid crystals, separation walls were formed using negative photo resister in boundary area between sub-pixels, Through the optimization of the material concentrations and UV irradiation condition, vivid R, G, B colors were achieved.

• Current Optics and Photonics
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• v.1 no.4
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• pp.389-395
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• 2017

This paper investigates a method to improve the lighting performance of white light-emitting diodes (WLEDs), which are packaged using two separate remote phosphor layers, a yellow-emitting YAG:Ce phosphor layer and a red-emitting ${\alpha}-SrO{\cdot}3B_2O_3:Sm^{2+}$ phosphor layer. The thicknesses of these two layers are $800{\mu}m$ and $200{\mu}m$, respectively. Both of them are examined in conditions where the average correlated color temperatures (CCT) are 7700 K and 8500 K. For this two-layer model, the concentration of red phosphor is varied from 2% to 30% in the upper layer, while in the lower layer the yellow phosphor concentration is kept at 15%. It was found interestingly that the lighting properties such as color rendering index (CRI) and luminous flux are enhanced significantly, while the color uniformity is maintained in a relatively close range to the one of one-layer configuration (measured at the same correlated color temperature). Besides, the transmitted and reflected light of each phosphor layer are revised by combining Kubelka-Munk and Mie-Lorenz theories. Through analysis, it is demonstrated that the packaging configuration of two-layer remote phosphor that employs red-emitting ${\alpha}-SrO{\cdot}3B_2O_3:Sm^{2+}$ phosphor particles provides a practical solution for general WLEDs lighting.

• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.1109-1111
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• 2008

High efficacy white OLEDs with low voltage, high quantum efficiency and outcoupling fixtures achieve total power efficacies of 89 lm/W to 102 lm/W, operating voltages between 2.8 V and 3.5 V at correlated color temperatures of 2,800 - 3,900 K and color rendering ~70, at 1,000 nits.

• Korean Journal of Optics and Photonics
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• v.32 no.5
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• pp.220-229
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• 2021

The optical characteristics of high-power direct-lit white light-emitting diode (LED) lighting were investigated, where a quantum dot (QD) film was adopted to enhance the color-rendering index (CRI). The transmittance of the diffuser plate and the concentration of the QD film were varied in this study. The color coordinates and the correlated color temperature (CCT) did not show any appreciable change, while the CRI values increased slightly as the transmittance of the diffuser plate decreased. The investigated optical properties were nearly independent of the viewing angle, and the luminance distribution was close to Lambertian. The CCT decreased from approximately 6000 K to approximately 4000 K as the concentration of the QD film increased from 0 to 7.5 wt%, which was due to the enhanced red component in the emission spectrum. The CRI increased to approximately 95 for some optical configurations of the lighting. These results demonstrate that glare-free, color-changeable, high-rendering LED lighting can be realized by using a combination of a diffuser plate of appropriate transmittance and a red QD film.

• Korean Journal of Materials Research
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• v.21 no.5
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• pp.250-254
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• 2011

We have synthesized bluish-green, highly-efficient $BaSi_2O_2N_2:Eu^{2+}$ and $(Ba,Sr)Si_2O_2N_2:Eu^{2+}$ phosphors through a conventional solid state reaction method using metal carbonate, $Si_3N_4$, and $Eu_2O_3$ as raw materials. The X-ray diffraction (XRD) pattern of these phosphors revealed that a $BaSi_2O_2N_2$ single phase was obtained. The excitation and emission spectra showed typical broadband excitation and emission resulting from the 5d to 4f transition of $Eu^{2+}$. These phosphors absorb blue light at around 450 nm and emit bluish-green luminescence, with a peak wavelength at around 495 nm. From the results of an experiment involving Eu concentration quenching, the relative PL intensity was reduced dramatically for Eu = 0.033. A small substitution of Sr in place of Ba increased the relative emission intensity of the phosphor. We prepared several white LEDs through a combination of $BaSi_2O_2N_2:Eu^{2+}$, YAG:$Ce^{3+}$, and silicone resin with a blue InGaN-based LED. In the case of only the YAG:$Ce^{3+}$-converted LED, the color rendering index was 73.4 and the efficiency was 127 lm/W. In contrast, in the YAG:$Ce^{3+}$ and $BaSi_2O_2N_2:Eu^{2+}$-converted LED, two distinct emission bands from InGaN (450 nm) and the two phosphors (475-750 nm) are observed, and combine to give a spectrum that appears white to the naked eye. The range of the color rendering index and the efficiency were 79.7-81.2 and 117-128 lm/W, respectively. The increased values of the color rendering index indicate that the two phosphor-converted LEDs have improved bluish-green emission compared to the YAG:Ce-converted LED. As such, the $BaSi_2O_2N_2:Eu^{2+}$ phosphor is applicable to white high-rendered LEDs for solid state lighting.

• Journal of KIISE:Computer Systems and Theory
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• v.27 no.5
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• pp.441-449
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• 2000

Binary volume data has its widespread use in the application of color volume rendering and surgical simulation system where gray-scale volume is inappropriate. For the efficient representation of binary volume, this paper proposes a new data structure - the Slice-based Binary Shell (SBS) - along with its rendering algorithm. Since SBS stores the minimal set of surface voxels in slice order and supports the direct computation of voxel coordinates, it shows high efficiency for rendering multiple objects. The rendering algorithm of SBS running on a PC with no specialized hardware renders more than one hundred binary objects in a second.

• Journal of The Korean Digital Architecture Interior Association
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• v.5 no.1
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• pp.9-16
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• 2005

In Interior design, light is the most important factor in deciding color, texture and illumination level which are the basic factors of spatial design. To apply rendering technologies on prediction of illuminating effect, it is important to understand and analyse the basic properties of the illumination models that are local illumination model and global illumination model. The illumination models in computer graphics express the factors which determine the surface color, texture and light distribution through the reflection. The purpose of this study is to propose the best way of shading algorithm in interior space provided by the computer, based on the experimental analysis that 5 shading methods are applied to the interior space. The results of this study were as followed. 1) Local illumination models that are Lambert shading, Ground shading and Phong shading are not suitable to the prediction of interior illumination effect. 2) Ray tracing that is global illumination model could be adopted to interior illumination effects. Ray tracing is a very versatile algorithm because of the large range of lighting effects it can model. 3) Neither radiality nor ray tracing offers a complete solution for simulating all interior illumination effects. 4) Radiosity excels at rendering diffuse-to-diffuse inter-reflections and ray tracing excels at rendering specular reflections. By merging both shading techniques, that offers the best of both. Using computer technologies to simulate lighting in preliminary design stage which will provide information for designers and occupants to determine the effect of using artificial light sources at each stage of their design process. Further study in illumination analysis, prediction of illumination effect, and lighting calculation is required as computer media expands.

• Journal of the Korea Computer Graphics Society
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• v.29 no.3
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• pp.93-103
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• 2023

The problem of reconstructing three-dimensional models of people and objects from color and depth images captured by low-cost RGB-D cameras has long been an active research area in computer graphics. Color and depth images captured by low-cost RGB-D cameras are represented as point clouds in three-dimensional space, which correspond to discrete values in a continuous three-dimensional space and require additional surface reconstruction compared to rendering using polygonal models. In this paper, we propose an effective ray-tracing based technique for visualizing point clouds rather than polygonal models. In particular, our method shows the possibility of an effective rendering method even in mobile environment which has limited performance due to processor heat and lack of battery.

• Journal of the Korea Computer Graphics Society
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• v.9 no.1
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• pp.11-18
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• 2003

본 논문에서는 회화적 렌더링에서 칼라변환을 이용한 브러쉬 스트로크의 생성에 관한 새로운 알고리즘을 제안한다. 본 논문의 브러쉬 스트로크 생성을 위한 전체적인 구성은 다음과 같다. 첫째, 두 장의 사진(한 장의 소스 이미지와 한 장의 참조 이미지)을 입력으로 하여 칼라 변환 이론을 적용하여 색상 테이블이 바뀐 새로운 이미지를 생성한다. 이 방법은 소스 이미지의 칼라 분포 형태를 창조 이미지의 칼라 분포 형태로 변환하기 위해, 선형 히스토그램 매칭이라 불리는, 간단한 통계학적 방법을 이용한다. 둘째, 가우시안 블러링과 소벨 필터를 이용하여 에지를 검출한다. 검출된 에지는 브러쉬 스트로크 렌더링 시 에지 부분에서 스트로크를 클리핑 함으로써 이미지의 윤곽선 보존을 위해 사용된다. 셋째, 브러쉬 스트로크의 방향을 결정하기 위한 방향맵을 생성한다. 방향맵은 입력 영상에 대한 영역 분할 및 병합을 토대로 만들어진다. 영역별 각 픽셀들에 대해 이미지 그래디언트에 기초한 일정한 방향을 부여함으로써 방향맵을 구성한다. 넷째, 구성된 방향맵을 참조하여 브러쉬 스트로크 생성의 기초가 되는 베지어 곡선(Bezier Curve)의 제어점(Control point)을 설정한다. 실제 회화작품에서 사용되는 브러쉬 스트로크는 일반적으로 곡선의 형태를 이루므로 곡선 표현이 가능한 베지어 곡선을 이용하여 브러쉬 스트로크를 표현하였다. 마지막으로, 생성된 브러쉬 스트로크를 에지부문에서 클리핑하고 배경색을 참조하여 블렌딩하거나 퐁 조명 모델을 이용하여 이미지에 적용하게 된다.