• Journal of the Korean Graphic Arts Communication Society
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• v.18 no.1
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• pp.141-155
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• 2000

To examine how the difference of molecular weight distribution of cellulase influenced the beating process according to surface pore size of the fiber, high molecular weight enzyme and low one were applied to soft wood pulp, hard wood pulp, cotton linter pulp. Some enzymes with the distribution of low molecular weight penetrated into cellulose in the proportion of surface pore size and the results were negative as like : the low viscosity, decrease of refining Yield, decrease of fine fibers content and so on. But in cotton linter pulp in the small surface area, the fiber softness was increased and it had a positive result that the paper intensity was high. Other enzymes with the distribution of high molecular weight had an enzyme reaction on the most surfaces of cellulose. They were effective in eliminating the fuzz of hydrophile fine fibers and the freeness was increased.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.48 no.2
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• pp.83-90
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• 2016

Increasing the amount of filler in paper is of high interest for paper industry while maintaining its key sheet quality properties. In this study, a MFC-GCC composite, made through a co-grinding NBSK (Northern bleached softwood kraft) pulp with a ground calcium carbonate (Intracarb 60), was used as a strength aid in paper in order to evaluate a potential cost reduction through filler increase without sacrificing paper quality. Hand-sheets were made of NBSK and/or eucalyptus pulp by using white water recirculation in a Tappi sheet former and was compared its properties without or with MFC additions at different filler levels. It was found that the MFC-GCC composite has a large surface area compared to the fiber, allowing the formation of more hydrogen bonds in the web, thus giving natural strength to the paper. Overall results are encouraging that the MFC-GCC composite allows papermaker to reduce basis weight and maintain critical sheet properties.

• The Journal of the Korean dental association
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• v.11 no.3
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• pp.199-203
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• 1973

Various concentration of formaldehyde solution (1%, 5%, 10%) were applied to cut pulp surface, for 3 minutes and the remaining pulp were carefully examined histo-pathologically. The result were as follows, 1. One week survival group which were treated by 1% formaldehyde solution showed seperation of odontoblast layer randomly and the weil's zone was undistinguishable. Deeper portion of this area was necrotic or coagulated. 2. Two week survival group which were treated 1% formaldehyde solution showed necrotic appearance spread from odontoblastic layer to weil's zone. 3. One and two week survival group which were treated 5% formaldehyde solution showed the odontoblastic layer was highly necrotic, under this zone empty net-work was seen. 4. One and two week survival group treated 10% formaldehyde solution showed complete destruction of pulp.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 2006.06b
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• pp.349-352
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• 2006

The conventional pulping processes in Iran were reviewed in this paper. On account of forest resources restriction, a considerable extent of non-harvestable hardwood forests, the possibility of accessable non-wood resources and Poplar fast-growing species for using in pulp and paper industry was investigate. The cultivated area and abundance of each mentioned raw material (Wheat Straw, Sugarcane Bagasse, Poplars) were specified and the quality of their produced papers were compared in strength and opacity properties. Spruce species data was used for experiments comparisons. Regarding to environmental pollutions, low yield, inflexibility in wood and non-wood species resulted from the existent conventional processes of paper manufacturing, APMP is recommended due to high quality paper, desirable opacity properties, high yield and also the usage for all the raw materials.

• The Journal of Korea Assosiation for Disability and Oral Health
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• v.10 no.2
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• pp.84-88
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• 2014

Traditional method of pulpectomy for a necrotic primary anterior tooth was done on lingual side. But it could not recover the discoloration of crown effectively. For the purpose of treating the discoloration of crown after lingual pulpectomy, additional methods of crown restoration were needed like : celluloid crown, open-faced crown, rasin-faced crown. Neverthless, these kinds of complete coverage methods had some disadvantages such as possibility of tooth fracture by increased tooth preparation. In order to overcome the shortcomings of lingual pulpectomy, labial treatment could be considered as an alternative. It is a method that treats necrotic pulp through the labial access opening. After finishing the pulp treatment, discolored labial tooth structure was removed extending from access opening. Discoloration of deep area could be masked effectively using opaque sealant. Cavity on labial side was restored with composite resin. This labial approach method has several advantages. First, it gives a direct vision for effective pulp treatment which is also very useful for children with poor behavior. Second, most of lingual tooth structure could be saved and occlusal contact of lingual surface remains undisrupted. Only nonfunctional discolored labial surface may removed. Third, complete removal of discolored part of a labial tooth and immediate resin restoration could be done effectively after pulp treatment. Moreover, it also could be used for pulp treatment having serious dental caries on labial surface with sound lingual tooth structure. This report presents cases with discolored upper anteior primary tooth, approaching labial side with successful restoration.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 2011.04a
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• pp.169-169
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• 2011

Xylans are polysaccharides present in large amounts in cell walls of land plants. However, during kraft cooking, a high portion of hemicelluloses including xylans are dissolved in the cooking liquor. In the current trend for a more effective utilization of biomass, attention has been paid to the exploitation of xylans as strength-enhancing additives for paper. It is believed that surface xylan adds flexibility to the cell wall/fiber surface, resulting in stronger fiber-fiber joints or greater contact area between the fibers. Accordingly, there is proposal for a new pulping process involving the extraction of xylan prior to pulping, followed by their re-adsorption on the unbleached pulp. A suitable bleaching process should be employed then, which ought to does not only improve the brightness of the pulp, but also remain the effect of the adsorption of xylan on pulp fibers. The objective of this research was to investigate the impact of hydrogen peroxide bleaching on the properties of unbleached hardwood kraft pulp pretreated with birchwood xylan by measuring optical properties (brightness, post color number, opacity) as well as physical properties (tensile index, tearing index, bulk) of handsheets made from the bleached pulp. In the meantime, the influence of process variables of peroxide bleaching including bleaching temperature, time, initial pH and $MgSO_4$ dosage were studied.

• Journal of Oral Medicine and Pain
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• v.46 no.2
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• pp.21-32
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• 2021

Purpose: The purpose of the present study was to investigate the correlation between age and 34 radiomorphometric parameters on panoramic radiographs, and to provide generalized linear models (GLMs) as a non-invasive, inexpensive, and accurate method to the forensic judgement of living individual's age. Methods: The study included 417 digital panoramic radiographs of Korean individuals (178 males and 239 females, mean age: 32.57±17.81 years). Considering the skeletal differences between the sexes, GLMs were obtained separately according to sex, as well as across the total sample. For statistical analysis and to predict the accuracy of the new GLMs, root mean squared error (RMSE) and adjusted R-squared (R²) were calculated. Results: The adjusted R²-values of the developed GLMs in the total sample, and male and female groups were 0.623, 0.637, and 0.660, respectively (p<0.001), while the allowable RMSE values were 8.80, 8.42, and 8.53 years, respectively. In the GLM of the total sample, the most influential predictor of greater age was decreased pulp area in the #36 first molar (beta=-26.52; p<0.01), followed by the presence of periodontitis (beta=10.24; p<0.01). In males, the most influential factor was the presence of periodontitis (beta=9.20; p<0.05), followed by the number of full veneer crowns (beta=2.19; p<0.001). In females, the most influential predictor was the presence of periodontitis (beta=18.10; p<0.001), followed by the tooth area of the #16 first molar (beta=-11.57; p<0.001). Conclusions: We established acceptable GLM for each sex and found out the predictors necessary to age estimation which can be easily found in panoramic radiographs. Our study provides reference that parameters such as the area of tooth and pulp, the number of teeth treated, and the presence of periodontitis should be considered in estimating age.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.41 no.5
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• pp.33-37
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• 2009

Hanji is a traditional Korean handmade paper, made of bast fibers of the paper mulberry. Its fiber furnish is much more expensive than wood fiber furnish. Hanji with a low basis weight requires additional opacity and smoothness for better writing and printing. Filler such as calcium carbonate can not be used to raise the opacity of Hanji because of its low retention in low basis weight paper and the high freeness of the Hanji fiber furnish. Addition of red algae pulp, which is prepared from marine red algae to the Hanji fiber furnish negated retention problems happening in the case of mineral filler addition, and produced a substantial improvement in the opacity and smoothness of Hanji. The higher retention was due to the much larger size of the red algae fibers compared to the mineral fillers. The improvement in opacity and smoothness were also due to the shape of the red algae fibers: that red algae fibers are narrower in widths and shorter in lengths than wood fibers results in increased surface area and smoothness.

• Restorative Dentistry and Endodontics
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• v.20 no.1
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• pp.342-350
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• 1995

To determine the factors which affect the flow of dentinal fluid through cat dentinal tubules in vivo, the flow of fluid was measured by observing the movement of the fat droplets of dilute milk in a glass capillary with a microscope connected to the monitor. After measuring the exposed area of dentin, hydraulic conductances of dentin were calculated. The mean pressure which stoped the outward flow of dentinal fluid was 9.5mmHg. The hydraulic conductance of dentin under the condition of pulp exposed was increased by 21 % from that under the condition of dentin exposed. Under the conditions of pulp cut and pulp removed, the hydraulic conductances of dentin were increased by 22 % and 31 % respectively from that under the condition of dentin exposed. These results show that the direction and rate of dentinal fluid flow in cat dentin is affected mainly by the hydrostatic pressure of interstitial fluid of pulp tissue in the state of low compliance. Both of the osmotic effect produced by the protein constituents of interstitial fluid across the odontoblast tell layer and the change of interstitial fluid pressure produced by the state of the microcirculation of the pulp also affect the direction and rate of dentinal fluid in some degree.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.29 no.4
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• pp.53-63
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• 1997

Most cellulose resources come from the higher plants, but bacteria also synthesize same cellulose as in plants. Many scientists have been widely studied on the bacterial cellulose, the process development, manufacturing, even marketing of cellulose fibers. The bacterial celluloses are very different in its physical and morphological structures. These fibers have many unique properties that are potentially and commercially beneficial. The fine fibers can produce a smooth paper with enchanced its strength property. But there gave been few reports on the mechanical properties of the processing of bacterial cellulose into structural materials. This study were performed to elucidate the mechanical properties of sheets prepared from bacterial cellulose. Also reinforcing effect of bacterial cellulose on the conventional pulp paper as well as surface structures by scanning electron microscopy were discussed. Paper made from bacterial cellulose is 10 times much stronger than ordinary chemical pulp sheet, and the mixing of bacterial cellulose has a remarkable reinforcing effect on the papers. Mechanical strengthes were increased with the increase of bacterial cellulose content in the sheet. This strength increase corresponds to the increasing water retention value and sheet density with the increase of bacterial cellulose content. Scanning electron micrographs were shown that fine microfibrills of bacterial celluloses covered on the surfaces of hardwood pulp fibers, and enhanced sheet strength by its intimate fiber bonding.