• Current Optics and Photonics
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• v.1 no.2
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• pp.118-124
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• 2017

Color rendering index (CRI) and luminous efficacy (LE) are two key performance factors of white LEDs (WLED). While most recent works in optics focus on methodology to improve these factors, little attention has been dedicated to chemical composition of materials. This paper studies the effect of $Sr_{2.4}1F_{2.59}B_{20.03}O_{74.8}:Eu_{0.12},Sm_{0.048}$ phosphor (SrSm), in terms of concentration and particle size on CRI and LE of 8500 K - WLEDs. Importantly, the molar mass of the componential ions in SrSm are calculated to shed light on the connection between the chemical composition of the material of interest and the performance of WLEDs. Results show that CRI can be improved to a value of around 86 by boosting red-light components in WLEDs, for all 3 major configurations: conformal, in-cup, and remote phosphor. CRI value tends to decrease with larger size of particles, while LE value goes in the reverse direction. On the other hand, both CRI and LE appear to be reduced at higher concentration of SrSm. This light attenuation is analyzed by using the Lambert-Beer law and Mie-scattering theory.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.30 no.3
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• pp.30-38
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• 2016

In this research, a 6W white LED package with a Glass Remote Phosphor was developed to improve the life of an LED package. The Glass Remote Phosphor was fabricated by the Phosphor in Glass (PiG) method, wherein phosphor YAG:Ce was mixed with glass frit and then heat treated. A paste with 75wt.% of a phosphor substance and 25wt.% glass frit was coated on a glass substrate two times using the screen-printing technique and heat-treated at $800^{\circ}C$ ; this structure gave a luminous efficacy of 136.1lm/W, color rendering index of 74Ra, and color temperature of 5,342K, thus satisfying the requirements as a light source for lighting. Moreover, an IES LM-80 accelerated life test was conducted on the same LED package for 6,000h in order to estimate the L70 lifetime based on IES TM-21. The results showed guaranteed lifetimes of 213,000h at $55^{\circ}C$, 245,000h at $85^{\circ}C$, and 209,000h at $95^{\circ}C$.

• Korean Journal of Remote Sensing
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• v.24 no.3
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• pp.245-250
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• 2008

According to public and industrial interests on mobile graphics, a preliminary implementation regarding 3D feature visualization system on cell phone was performed using M3G API, one of the de-facto standards for mobile 3D graphic API. Through this experiment, it is revealed that scene graph structure and 3D mobile file format supported from this API is useful one for 3D geo-modeling and rendering in mobile environment. It is necessary that 3D mobile graphic standards can be considered as one component of current mobile GIS services standards to provide value-added 3D GIS contents.

• Korean Journal of Remote Sensing
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• v.22 no.5
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• pp.351-356
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• 2006

Based on current practical needs for geo-spatial information on mobile platform, the main theme of this study is a design and implementation of dynamic 3D terrain rendering system using spaceborne imagery, as a kind of texture image for photo-realistic 3D scene generation on mobile environment. Image processing and 3D graphic techniques and algorithms, such as TIN-based vertex generation with regular spacing elevation data for generating 3D terrain surface, image tiling and image-vertex texturing in order to resolve limited resource of mobile devices, were applied and implemented by using graphic pipeline of OpenGL|ES (Embedded System) API. Through this implementation and its tested results with actual data sets of DEM and satellite imagery, we demonstrated the realizable possibility and adaptation of complex typed and large sized 3D geo-spatial information in mobile devices. This prototype system can be used to mobile 3D applications with DEM and satellite imagery in near future.

• Korean Journal of Remote Sensing
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• v.19 no.6
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• pp.457-464
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• 2003

Triangulated irregular network is one of the most frequently used terrain modeling methods. It represents terrain precisely using only a small amount of data, and enables fast rendering of terrain. In this paper, ridges and valleys are extracted from the terrain, and used as a set of vertices for the construction of triangulated irregular network. An experiment shows the new method reduces the time for construction of the triangulated irregular network significantly with almost equal amount of induced error.

• Korean Journal of Remote Sensing
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• v.28 no.2
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• pp.245-253
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• 2012

The public and civilian demands regarding 3D geo-spatial information processing on mobile device including smartphone are increasing. But there are few actual implementations or application cases. This work is to present some results by a prototype implementation of 3D terrain information visualization function with satellite image and DEM using HTML5 WebGL, which is a web-based graphic library under the standardization process. This is a useful standard for cross-platform operation for 3D graphic rendering without other plug-in modules. As the results, in the different types of operating system or browser in a personal computer or a smartphone, it shows same rendering results, as long as they support HTML5 WebGL. As well;geo-metadata search and identification functions for data sets for 3D terrain visualization process are added in this implementation for the practical aspect.

• Proceedings of the Korea Contents Association Conference
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• 2004.11a
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• pp.402-407
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• 2004

Since the world wide web, simple and convenient tool, has proposed, the Internet became the most simple network resource which provide many informations of the world. Furthermore, various methodologies are developed to support the dynamic service such as 3D View web service. We will propose the volume rendering view program that interactively visualize the 3D data on the web. The 3D Data is obtained by stacking the 2D images along the z-direction. We also employ the COM based OCX control which is a kind of Active component. This web program will contribute the diagnosis of the diseases through the 3D visualization and image analysis functions at remote places.

• Korean Journal of Remote Sensing
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• v.20 no.6
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• pp.409-418
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• 2004

LOD is a widely used technique in 3D game and animation to represent large 3D data sets smoothly in real-time. Most LOD algorithms use a binary tree to keep the ancestor information. A new algorithm proposed in this paper, however, do not keep the ancestor information, thus use the less memory space and rather increase the rendering performance. To verify the efficiency of the proposed algorithm, performance comparison with ROAM is conducted in real-time 3D terrain navigation. Result shows that the proposed algorithm uses about 1/4 of the memory space of ROAM and about 4 times faster than ROAM.

• Proceedings of the Korean Information Science Society Conference
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• 2004.10b
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• pp.661-663
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• 2004

여러 분야에서 산출되고 있는 볼륨 데이터의 크기는 점점 더 방대해지고 있는 추세에 있으며, 이러한 방대한 데이터 속에 내재된 유용한 정보를 알아내기 위해 데이터 전체가 아니라 어떤 특정 부분을 효과적으로 액세스하고 이를 고해상도로 가시화 하는 것은 매우 중요한 문제로 대두되고 있다. 본 논문에서는 방대한 볼륨 데이터 가시화를 위친 개발된 클라이언트-서버 기반의 볼륨 렌더링 시스템에 대해 소개한다. 범용 PC상에서 GUI형태로 구현된 클라이언트는 데이터 서버와 접속하여 특정 영역에 대한 부분 볼륨 데이터를 요청하는데, 이때 데이터 서버가 전송하는 데이터는 클라이언트의 텍스춰 메모리 크기보다 작거나 같도록 리샘플링된 것이며, 클라이언트는 이를 받아 실시간 렌더링을 수행한다. 또한 특정 영역에 대한 고해상도의 영상을 원하는 경우, 클라이언트는 렌더링 서버와 접속하여 다양한 형태의 고화질 영상을 얻을 수 있다. 본 시스템은 매우 방대한 크기의 데이터에 대한 가시화가 필수적인 자연과학, 의학, 공학 분야에서 효과적으로 응용될 수 있을 것이다.

• Proceedings of the KSRS Conference
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• 2003.11a
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• pp.753-756
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• 2003

The paper presents the results of the project GISMO, which aimed on generating and interactively visualising a 3D urban landscape model of the city of Stuttgart, Germany. With respect to the desired flexibility to support walkthrough and flyover applications, a combined approach using continuous level of detail, the impostor technique and a method for generalizing 3D building models was used to speed up the visualization. To reduce the costs of the project, the data collection tools and the visualization environment was built solely with open-source software.