• Proceedings of the IEEK Conference
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• 2005.11a
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• pp.403-406
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• 2005

The purpose of this paper is to propose ways to remove false color noise (FCN) generated during de-mosaicing on RGB Bayer pattern images. In case of images sensors adapting Bayer pattern color filters array (CFA), de-mosaicing is conducted to recover the RGB color data in single pixels. Here, FCN phenomena would occur where there is clearer silhouette or contrast of colors. The FCN phenomena found during de-mosaicking process appears locally in the edges inside the image and the proposed method of eliminating this is to convert RGB color space to YCbCr space to conduct smoothing process. Moreover, for edges where different colors come together, censoring based smoothing technique is proposed as a way to minimize color blurring effect.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 2004.07a
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• pp.19-42
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• 2004

Sizing properties in paper are generally developed through the application of both internal and surface sizes. Rosin, wax, and synthetic sizes including ASA, AKD, and stearic anhydride are and have been used to provide wet-end sizing to paper. In many cases, the use of some of these sizes leads to runnability problems that are inherent in the wet-end operation. Variability in furnish, fines, broke, filler, water chemistry, conductivity, and pH control impacts the wet-end operation. Size press chemicals including starch and polymers such as styrene-acrylic, styrene-maleic, and styrene acrylate emulsions are used in conjunction with internal sizes to improve the paper surface for printing and strength properties, porosity, and opacity improvement. This paper will discuss results from a new, proprietary formulation and process that allows application of sizing chemistry more totally at the size press with reduced emphasis on wet end sizing. Runnability issues are thus minimized at the wet-end, chemical usage is more efficient, and significant cost savings can be realized. Case histories will be presented illustrating the advantages of this new application in commercial trials.

• Journal of the Korean Ceramic Society
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• v.37 no.10
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• pp.987-993
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• 2000

Bayer 공정은 보오크사이트로부터 수산화알루미늄을 추출시키는 가장 일반적인 방법으로서 공정 조건에 따라 수산화알루미늄의 1차입자경, 입도분포도 및 생산효율 등이 달라지게 된다. 이러한 수산화알루미늄의 특성에 영향을 미치는 석출인자로는 가성소다 농도, 석출온도, 종자투입량 및 알루미나와 가성소다 농도비 등이 있다. 본 실험에서는 이러한 각각의 인자들이 수산화알루미늄 석출시 입자성장에 미치는 영향을 연구하였다. 그 결과 입자성장에 가장 큰 영향력을 미치는 인자는 석출온도와 종자 투입량이며 A/C비 및 가성소다 농도는 큰 영향을 주지 않음을 알 수 있었다.

• ETRI Journal
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• v.38 no.1
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• pp.164-173
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• 2016

Demosaicing, or color filter array (CFA) interpolation, estimates missing color channels of raw mosaiced images from a CFA to reproduce full-color images. It is an essential process for single-sensor digital cameras with CFAs. In this paper, a new demosaicing method for digital cameras with Bayer-like W-RGB CFAs is proposed. To preserve the edge structure when reproducing full-color images, we propose an edge direction-adaptive method using color difference estimation between different channels, which can be applied to practical digital camera use. To evaluate the performance of the proposed method in terms of CPSNR, FSIM, and S-CIELAB color distance measures, we perform simulations on sets of mosaiced images captured by an actual prototype digital camera with a Bayer-like W-RGB CFA. The simulation results show that the proposed method demosaics better than a conventional one by approximately +22.4% CPSNR, +0.9% FSIM, and +36.7% S-CIELAB distance.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.7
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• pp.205-215
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• 2013

In digital imaging system, Bayer pattern is widely used and the observed image is degraded by optical blur during image acquisition process. Generally, demosaicing and deblurring process are separately performed in order to convert a blurred Bayer image to a high resolution color image. However, the demosaicing process often generates visible artifacts such as zipper effect and Moire artifacts when performing interpolation across edge direction in Bayer pattern image. These artifacts are emphasized by the deblurring process. In order to solve this problem, this paper proposes a deblurring algorithm combined with edge directional color demosaicing method. The proposed method is consisted of interpolation step and region classification step. Interpolation and deblurring are simultaneously performed according to horizontal and vertical directions, respectively during the interpolation step. In the region classification step, characteristics of local regions are determined at each pixel position and the directionally obtained values are region adaptively fused. Also, the proposed method uses blur model based on wave optics and deblurring filter is calculated by using estimated characteristics of local regions. The simulation results show that the proposed deblurring algorithm prevents the boosting of artifacts and outperforms conventional approaches in both objective and subjective terms.

• Journal of the Korean Ceramic Society
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• v.52 no.3
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• pp.192-196
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• 2015

Low soda alumina powder was fabricated using silica (${\alpha}$-quartz) as an agent for removing soda components in the alumina. Quartz powder 2 mm in size was added to aluminum hydroxide obtained through the Bayer process, and then the mixture was heated at various temperatures. Finally, the heat-treated powders were sieved for classification. In this study, the effects of the quartz amount and heating temperature on the mechanism of removing soda were examined. A minimum soda content of 0.005 wt% was observed at the conditions of 15 wt% quartz (based on $Al(OH)_3$ amount) heat-treated at $1600^{\circ}C$ for 8 h. The soda components, such as $Na_2O$, NaOH, and $Na_2CO_3$, in alumina were ionized and activated at high temperature, and this facilitated the reaction with quartz silica and alumina producing nepheline. The advantages of using quartz include low iron content and low cost in comparison with the conventional de-soda process using chamotte, another silicate mineral.

• Clean Technology
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• v.18 no.1
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• pp.63-68
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• 2012

In this study, aluminum hydroxide ($Al(OH)_3$) was synthesized by Bayer process and sodium contained in $Al(OH)_3$ was removed with the acid solution such as HCl and acetic acid for the synthesis of high purity alumina. The bauxite produced in Queensland of Australia was used for the production of alumina by Bayer, and was crushed to a particle size of below 10 um by attrition mill. The crushed bauxite was treated in sodium hydroxide solution of 5 N for the elution of aluminum component. The elution of aluminum from bauxite was carried out at $140^{\circ}C$ and 3.4 atm in autoclave. The sample solution was separated to the red mud and liquid solution by filter paper. The elution of aluminum from bauxite was confirmed with changing a structure and aluminum content in both bauxite and red mud analyzed by XRD and EDX. Aluminum contained in the separated solution was crystallized to $Al(OH)_3$ with the addition of aluminum hydroxide used as the seed material. $Al(OH)_3$ powder obtained during the crystallization process was purified by several times washing with distillated water. It was also confirmed that the sodium remained in $Al(OH)_3$ powder is removed with acid solution. The purity of $Al(OH)_3$ powder produced in this study was 99.3% and the content of sodium was reduced to approximately 0.009% after the acid treatment.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.1
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• pp.906-913
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• 2015

The red mud generated from the Bayer alumina production process seriously threatens the environment and human safety. Therefore, the reduction and recycling of red mud is an urgent topic in the aluminum industry. In this study, the effects of four parameters, ultrasound power, reaction temperature, time, and acid concentration, on the leaching of Fe, Al from red mud was investigated. The major parameters influencing the metal recovery efficiency from red mud were ultrasound power and reaction temperature. The use of ultrasonic irradiation resulted in 1.72 and 1.28 times higher recovery efficiency for Fe and Al, respectively. The proper conditions for the recovery of the metal components present in the red mud is the ultrasound intensity (150 W), sulfuric acid concentration (4-6N), reaction temperature ($70^{\circ}C$), and reaction time (2 hours), etc.

• Journal of Broadcast Engineering
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• v.18 no.4
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• pp.619-630
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• 2013

In this paper, we propose an edge directed color demosaicing algorithm considering color channel correlation. The proposed method consists of local region classification step and edge directional interpolation step. In the first step, each region of a given Bayer image is classified as normal edge, pattern edge, and flat regions by using intra channel and inter channel gradients. Especially, two criteria and verification process for the normal edge and pattern edge classification are used to reduce edge direction estimation error, respectively. In the second step, edge directional interpolation process is performed according to characteristics of the classified regions. For horizontal and vertical directional interpolations, missing color components are obtained from interpolation equations based on intra channel and inter channel correlations in order to improve the performance of the directional interpolations. The simulation results show that the proposed algorithm outperforms conventional approaches in both objective and subjective terms.

• Journal of the Korean Ceramic Society
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• v.38 no.3
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• pp.267-273
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• 2001

Bayer process는 보오크사이트로부터 수산화알루미늄을 추출시키는 가장 일반적인 방법으로서 공정 조건에 따라 수산화알루미늄의 1차입자경, 입도분포도 및 생산효율 등이 달라지게 된다. 이러한 수산화알루미늄의 특성에 영향을 미치는 석출인자로는 석출시간, 석출온도차($\Delta$T), 종자 첨가시 함께 투입되는 공정순환액(spent liquor) 및 종자크기 등이 있다. 본 실험에서는 이러한 각각의 인자들이 수산화알루미늄 석출시 입자성장에 미치는 영향을 연구하였다. 그 결과 석출시간이 길수록, 정온석출 보다는 냉각석출의 경우가, 또한 공정순환액이 첨가되지 않을수록 석출율은 증가하나 입자크기에는 영향을 주지 않았으며 입자성장에 가장 큰 영향력을 미치는 인자는 투입 종자크기로 나타났다.