• International Journal of Internet, Broadcasting and Communication
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• 제12권2호
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• pp.1-7
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• 2020

The secure access the lighting, Heating, ventilation, and air conditioning (HVAC), fire safety, and security control boxes of building facilities is the primary objective of future smart buildings. This paper proposes an authorized user access to the electrical, lighting, fire safety, and security control boxes in the smart building, by using color grid coded optical camera communication (OCC) with face recognition Technologies. The existing CCTV subsystem can be used as the face recognition security subsystem for the proposed approach. At the same time a smart device attached camera can used as an OCC receiver of color grid code for user access authentication data sent by the control boxes to proceed authorization. This proposed approach allows increasing an authorization control reliability and highly secured authentication on accessing building facility infrastructure. The result of color grid code sequence received by the unauthorized person and his face identification allows getting good results in security and gaining effectiveness of accessing building facility infrastructure. The proposed concept uses the encoded user access authentication information through control box monitor and the smart device application which detect and decode the color grid coded informations combinations and then send user through the smart building network to building management system for authentication verification in combination with the facial features that gives a high protection level. The proposed concept is implemented on testbed model and experiment results verified for the secured user authentication in real-time.

• Current Optics and Photonics
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• 제5권4호
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• pp.409-420
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• 2021

We propose a method to synthesize a color non-hogel-based computer-generated-hologram (CGH) from light field data of a three-dimensional scene with a hologram pixel pitch shared for all color channels. The non-hogel-based CGH technique generates a continuous wavefront with arbitrary carrier wave from given light field data by interpreting the ray angle in the light field to the spatial frequency of the plane wavefront. The relation between ray angle and spatial frequency is, however, dependent on the wavelength, which leads to different spatial frequency sampling grid in the light field data, resulting in color aberrations in the hologram reconstruction. The proposed method sets a hologram pixel pitch common to all color channels such that the smallest blue diffraction angle covers the field of view of the light field. Then a spatial frequency sampling grid common to all color channels is established by interpolating the light field with the spatial frequency range of the blue wavelength and the sampling interval of the red wavelength. The common hologram pixel pitch and light field spatial frequency sampling grid ensure the synthesis of a color hologram without any color aberrations in the hologram reconstructions, or any loss of information contained in the light field. The proposed method is successfully verified using color light field data of various test or natural 3D scenes.

• 한국인터넷방송통신학회논문지
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• 제18권6호
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• pp.91-97
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• 2018

본 논문은 VLC (Visible Light Communication)의 컬러그리드 기반 가시광 IoT 도어락 시스템의 구현 가능성을 제시한다. 이 논문에서 논의된 컬러그리드 기반의 VLC 변조 방식은 빛의 직진성과 빛의 특성 인 풍부한 주파수 자원을 이용한다. 이 시스템의 성능 결과는 비트 오류율 (BER) 및 신호 대 잡음비 (SNR) 시뮬레이션을 사용하는 기존 변조 방식과 비교한다. 채널 모델과 관련하여 제안된 혼합변조 방식은 NLOS (Non Line Of Sight)를 제외한 가장 가까운 LOS (Line Of Sight)를 선택한다. 이 논문의 실험은 실내 환경에서 Tx와 Rx 사이에서 3m의 거리에서 전력 dB을 변화시킴으로써 수신 된 심볼의 에러율을 보여준다. 성능 결과 및 실험을 통해 제안 된 컬러그리드 기반 변조 방식의 우수성을 보인다.

• 한국정보통신학회논문지
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• 제14권1호
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• pp.213-224
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• 2010

본 논문에서는 보정 영상을 프로젝터가 표현할 수 있는 범위로 콘트라스트(contrast)를 조절하여 주는 요소(scaling factor)를 적용하여 색 보정영상을 획득하는 방법을 제안한다. 이 조절 요소는 입력영상과 사용된 표면의 평균 밝기를 이용하여 계산하였다. 또한 사용된 프로젝터 및 카메라의 특성화 과정에서 오는 오차와 부정확성을 해결하기 위하여 프로젝터와 카메라 양단간의 관계를 적용한다. 실험 결과에서 제안한 색 보정 방법이 임의의 표면으로 입력된 다양한 영상에 대하여 밝기를 유지하면서 클리핑 결함은 감소되어 화질이 개선된 것을 확인하였다.

• The Journal of Advanced Prosthodontics
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• 제15권3호
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• pp.145-154
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• 2023

PURPOSE. The objective of this study was to investigate how internal structures influence the overall and marginal accuracy of full arch preparations fabricated through additive manufacturing in different printing systems. MATERIALS AND METHODS. A full-arch preparation digital model was set up with three internal designs, including solid, hollow, and grid. These were printed using three different resin printers with nine models in each group. After scanning, each data was imported into the 3D data processing software together with the master cast, aligned and trimmed, and then put into the 3D data analysis software again to compare the overall and marginal deviation whose results are expressed using root mean square values and color maps. To evaluate the trueness of the resin model, the test data and reference data were compared, and the precision was evaluated by comparing the test data sets. Color maps were observed for qualitative analysis. Data were statistically analyzed by one-way analysis of variance and Bonferroni method was used for post hoc comparison (α = .05). RESULTS. The influence of different internal structures on the accuracy of 3D printed resin models varied significantly (P < .05). Solid and grid models showed better accuracy, while the hollow model exhibited poor accuracy. The color maps show that the resin models have a tendency to shrink inwards. CONCLUSION. The internal structure design influences the accuracy of the 3D printing model, and the effect varies in different printing systems. Irrespective of the kind of printing system, the printing accuracy of hollow model was observed to be worse than those of solid and grid models.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 추계학술대회
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• pp.1592-1597
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• 2004

Experimental studies were carried out to confirm the turbulent enhancement of the cooling system of nuclear reactor by large scale vortex generation in nuclear fuel rod bundle. The large scale vortex motions were generated by rearranging the inclination angles of mixing vanes to the coordinate directions. Experimental studies were carried out at Reynolds Number 60,000 with hydraulic condition. Normal variations of mean velocity and turbulent intensity in the rod bundle subchannel were measured by the 2-color LDV measurement system. The turbulence generated by split mixing vanes has small length scales so that they maintain only about 10DH after the spacer grid. On the other hand, the turbulences generated by the large scale vortex continue more and remain up $25D_{H}$ after the spacer grid.

• International Journal of Air-Conditioning and Refrigeration
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• 제9권2호
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• pp.77-84
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• 2001

Experimental and computational studies were carried out to investigate the turbulent heat transfer enhancement of the cooling system in nuclear reactor by large scale vortex generation. The large scale vortex motion was generated by rearranging the inclination angels of mixing vanes to the coordinate direction. Axial development of mean and turbulent velocities in the subchannels were measured by the 2-color LDV system. Eddy diffusivity concept based on $\kappa{-}\varepsilon$ model was employed to calculate the turbulent heat and momentum transfers in the subchannel. The turbulences generated by split mixing vanes has small length scales so that they maintain only about $10D_H$ after the spacer grid. On the other hand, the turbulences generated by the large scale vortex motions continue longer and remain up to $25D_H$ after the spacer grid.

• 디지털산업정보학회논문지
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• 제10권4호
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• pp.151-160
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• 2014

In this paper, a comparison of superpixel characteristics based on SLIC(simple linear iterative clustering) for several color feature spaces is presented. Computer vision applications have come to rely increasingly on superpixels in recent years. Superpixel algorithms group pixels into perceptually meaningful atomic regions, which can be used to replace the rigid structure of the pixel grid. A superpixel is consist of pixels with similar features such as luminance, color, textures etc. Thus superpixels are more efficient than pixels in case of large scale image processing. Generally superpixel characteristics are described by uniformity, boundary precision and recall, compactness. However previous methods only generate superpixels a special color space but lack researches on superpixel characteristics. Therefore we present superpixel characteristics based on SLIC as known popular. In this paper, Lab, Luv, LCH, HSV, YIQ and RGB color feature spaces are used. Uniformity, compactness, boundary precision and recall are measured for comparing characteristics of superpixel. For computer simulation, Berkeley image database(BSD300) is used and Lab color space is superior to the others by the experimental results.

• 한국정보과학회:학술대회논문집
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• 한국정보과학회 2007년도 한국컴퓨터종합학술대회논문집 Vol.34 No.1 (B)
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• pp.182-187
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• 2007

본 논문에서는 이미지 상에 나타난 색상 정보를 추출하기 위한 새로운 커널 메소드(Kernel method)인 Grid kernel을 제안한다. 제안한 Grid kernel은 Convolution kernel의 하나로 이미지 상에 나타나는 자질을 주변 픽셀에서 나타나는 자질로 정의 하고 이를 재귀적으로 적용함으로써 두 이미지를 비교한다. 본 논문에서는 제안한 커널을 차량 색상 인식 문제에 적용하여 차량 색상 인식 모델을 제안한다. 이미지 생성시 나타나는 주변 요인으로 인해 차량의 색상을 추출하는 것은 어려운 문제이다. 이미지가 야외에서 촬영되기 때문에 시간, 날씨 등의 주변 요인은 같은 차량이라 하더라도 다른 색상을 보이게 할 수 있다. 이를 해결하기 위해 Grid kernel이 적용된 차량 색상 인식 모델은 이미지를 HSV (Hue-Saturation-Value) 색상 공간으로 사상하여 명도를 배제하였다. 제안한 커널과 색상 인식 모델을 검증하기 위해 5가지 색상을 가진 차량 이미지를 이용하여 실험을 하였으며, 실험 결과 92.4%의 정확율과 92.0%의 재현율을 보였다.

• 디지털산업정보학회논문지
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• 제11권4호
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• pp.89-97
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• 2015

In this paper, a method of color image segmentation based on DBSCAN(Density Based Spatial Clustering of Applications with Noise) using compactness of superpixels and texture information is presented. The DBSCAN algorithm can generate clusters in large data sets by looking at the local density of data samples, using only two input parameters which called minimum number of data and distance of neighborhood data. Superpixel algorithms group pixels into perceptually meaningful atomic regions, which can be used to replace the rigid structure of the pixel grid. Each superpixel is consist of pixels with similar features such as luminance, color, textures etc. Superpixels are more efficient than pixels in case of large scale image processing. In this paper, superpixels are generated by SLIC(simple linear iterative clustering) as known popular. Superpixel characteristics are described by compactness, uniformity, boundary precision and recall. The compactness is important features to depict superpixel characteristics. Each superpixel is represented by Lab color spaces, compactness and texture information. DBSCAN clustering method applied to these feature spaces to segment a color image. To evaluate the performance of the proposed method, computer simulation is carried out to several outdoor images. The experimental results show that the proposed algorithm can provide good segmentation results on various images.