• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.32 no.3
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• pp.65-74
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• 2000

This study was carried out to acquire basic data necessary for the use of rice-straw chemical pulp. It investigated the proper bleaching conditions when rice-straw chemical pulps(alkaline sulfite-Na2S2O4 pulp) were bleached with the various kinds of bleaching agents. And physical properties of bleached pulps were tested. The results of this study were as follows; 1, The proper conditions of chlorine sequence were determined to be 4% concentration of chlorine 25$^{\circ}C$ of reaction temperature and 50 minutes of reaction time. 2. For calcium hypochlorite sequence the proper conditions of chemical concentration reac-tion temperature and reaction time were 3% 25$^{\circ}C$ and 20 minutes respectively. 3. For chlorine dioxide sequence the proper conditions were 1% concentration of chlorine dioxide 70$^{\circ}C$ of reaction temperature and 2hr. of reaction time. 4. The proper conditions of hydrogen peroxide sequence were 1.5% concentration of hydro-gen peroxide 70$^{\circ}C$ of reaction temperature and 1hr. of reaction time respectively. 5. When the rice-straw chemical pulp were bleached with four kinds of bleaching agents methioned above in the proper conditions respectively brightnesses were the order of chlorine dioxide calcium hypochlorite, chlorine, hydrogen peroxide. And strengthes of pulps bleached with chlorine dioxide and hydrogen peroxide were higher than those of pulps bleached with other bleaching agents.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 1999.11b
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• pp.164-171
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• 1999

A new technique for recycling process water was developed in order to reduce the calcium hardness of the closed OCC recycling system. Calcium ions present in the white water were precipitated as calcium carbonate by a reaction with sodium carbonate and the CaCO$_3$precipitates were easily removed from the system by a dissolved air flotation(DAF) method. After the DAF stage, CO$_2$-gas was purged into the water because the pH of Na$_2$CO$_3$-treated white water was reduced to neutral by CO$_2$gas. Since CaCO$_3$precipitate tends to stick onto the fine fiber surface and then is selectively removed from the water, a proper amount of suspended solid in the process water acts as an important factor in deciding the removal efficiency. By the application of Na$_2$CO$_3$addition - DAF - CO$_2$purging to the short circulated white water the calcium hardness was significantly reduced by 92% and more. The removal of calcium ions with fine fibers led to drainage improvement, reduction of fresh water consumption, and enhanced efficiency of wet-end chemicals.

• Restorative Dentistry and Endodontics
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• v.26 no.5
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• pp.387-392
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• 2001

When cavity floor is near the pulp, polymerization of light-activated restorations results in temperature increase. This temperature increase cause by both the exothermic reaction process and the energy absorbed during irradiation. Therefore instating base is required. Most frequently used insulating base is glass ionmer. The purpose of this study was to evaluate intrapulpal temperature changes of glass ionomer according to various curing intensity and curing time. Caries and restoration-free mandibular molars extracted within three months were prepared Class I cavity of 3$\times$6mm with high speed handpiece. 1mm depth of dentin was evaluated with micrometer in mesial and distal pulp horns. Pulp chambers were filled with 37.0$\pm$0.1$^{\circ}C$ water to CEJ. Chromium-alumina thermocouple was placed in pulp horn for evaluating of temperature changes. glass ionomer material was placed in 2mm. total curing time was 40s: continuous 40s, intermittent 20s, intermittent 10s. Glass ionomer material was cured with 300mW/$\textrm{cm}^2$, 550mW/$\textrm{cm}^2$ light curing unit. The results were as follows : 1. Temperature in pulp increased as curing unit power is increased. 2. Temperature in pulp more increased continuous emission than intermittent emission.

• Journal of Korean Society of Water and Wastewater
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• v.31 no.4
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• pp.289-296
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• 2017

Pulp and paper industry produces large volumes of wastewater and residual sludge waste, resulting in many issues in relation to wastewater treatment and sludge disposal. Contaminants in pulp and paper wastewater include effluent solids, sediments, chemical oxygen demand (COD), and biological oxygen demand (BOD), which should be treated by wastewater treatment processes such as coagulation and biological treatment. However, few works have been attempted to predict the treatment efficiency of pulp and paper wastewater. Accordingly, this study presented empirical models based on experimental data in laboratory-scale coagulation tests and compared them with statistical models such as artificial neural network (ANN). Results showed that the water quality parameters such as turbidity, suspended solids, COD, and UVA can be predicted using either linear or expoential regression models. Nevertheless, the accuracies for turbidity and UVA predictions were relatively lower than those for SS and COD. On the other hand, ANN showed higher accuracies than the emprical models for all water parameters. However, it seems that two kinds of models should be used together to provide more accurate information on the treatment efficiency of pulp and paper wastewater.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.37 no.1 s.109
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• pp.47-52
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• 2005

Enzymatic pulping properties of mixed office waste paper in standard disintegrator were investigated for successful enzymatic deinking of mixed office waste paper. Enzymatic pulping need more revolution in standard disintegrator than alkaline pulping and Cellusoft need more revolution than Denimax. The freeness of disintegrated pulp with enzyme was higher than those of disintegrated pulps with alkaline and heat killed enzyme. The freeness of disintegrated pulp with Denimax was higher than that of disintegrated pulp with Cellusoft. The freeness of disintegrated pulps were increased with a dosage of enzymes. The mechanical properties of disintegrated pulp were improved with enzyme addition comparing with heat killed enzyme. The tensile and burst index of hand sheet of disintegrated pulps with acidic Cellusoft were higher than that of others.

• Restorative Dentistry and Endodontics
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• v.38 no.4
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• pp.227-233
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• 2013

Objectives: The purpose of the study was to evaluate human dental pulp response to pulpotomy with calcium hydroxide (CH), mineral trioxide aggregate (MTA), and calcium enriched mixture (CEM) cement. Materials and Methods: A total of nine erupted third molars were randomly assigned to each pulpotomy group. The same clinician performed full pulpotomies and coronal restorations. The patients were followed clinically for six months; the teeth were then extracted and prepared for histological assessments. The samples were blindly assessed by an independent observer for pulp vitality, pulp inflammation, and calcified bridge formation. Results: All patients were free of clinical signs/symptoms of pulpal/periradicular diseases during the follow up period. In CH group, one tooth had necrotic radicular pulp; other two teeth in this group had vital uninflamed pulps with complete dentinal bridge formation. In CEM cement and MTA groups all teeth had vital uninflamed radicular pulps. A complete dentinal bridge was formed beneath CEM cement and MTA in all roots. Odontoblast-like cells were present beneath CEM cement and MTA in all samples. Conclusions: This study revealed that CEM cement and MTA were reliable endodontic biomaterials in full pulpotomy treatment. In contrast, the human dental pulp response to CH might be unpredictable.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.20 no.1
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• pp.79-89
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• 1990

The incidence and several characteristic features of fused and geminated teeth were studied radiographically, with full mouth periapical radiogram and pantomogram, in 4201 patients of mixed dentition and 5358 patients of permanent dentition. The obtained results were as follows: 1. The prevalence was revealed to 2.86%, 0.32%, 0.33%, and 0.06% in deciduous fused tooth, permanent fused tooth, deciduous geminated tooth and permanent geminated tooth respectively, and these anomalies were occured in female more than male. 2. Fused teeth were observed predominantly in lower anterior teeth area, especially in lateral incisor and canine region, and many cases of deciduous geminated tooth were observed in upper central incisor region. 3. Congenital missing rates of succedaneous tooth in deciduous fused teeth were 57.1 %, 85.7%, 71.0%, 69.0% in upper right and left central-lateral incisor regions, lower right and left lateral incisor-canine regions, respectively. 4. Prevalence of dental caries was 42.3%, 18.8% and 5.6% in deciduous fused, deciduous geminated and permanent fused tooth, respectively. 5. In classifying of fused and geminated teeth into 9 types, by following appearance such as number of crown, root, pulp chamber and pulp canal of those teeth, it was more favorable that Type Ⅰ(2 crown, 2 root, 2 pulp chamber, 2 pulp canal) in deciduous fused tooth and Type Ⅸ (I crown, 1 root, 1 pulp chamber, 1 pulp canal) in permanent fused tooth, deciduous and permanent geminated tooth.

• Journal of Biosystems Engineering
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• v.30 no.5 s.112
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• pp.285-292
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• 2005

Extrusion process and physical properties of extrudates of pulp powder (TMP, thermomechanical pulp fibers) mixed with expanding additives was evaluated to develop biodegradable packaging materials. To find out the optimum condition, the status of extrusion process, coefficient of elastic and expansion ratio of extrudates were tested on the composites (wheat flour, soluble starch, polyvinyl alcohol), blending conditions of composites and moisture contents of extrudates. In case of material composition, wheat flour played a key role to keep extrusion process irrespective of the added amounts of soluble starch and polyvinyl alcohol. The coefficient of elastic of extrudates was increased and the expansion ratio was reduced as the added amounts of wheat flour increased. Also, the coefficient of elastic of extrudates was decreased as the moisture content of extrudates increased. The lowest coefficient of elastic was 439.55 kPa under the condition, of pulp powder mixed with $20\%$ of wheat flour based on pulp weight and $10\%$ of soluble starch based on wheat flour weight and controlled $20\%$(wb) of moisture content.

• Restorative Dentistry and Endodontics
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• v.7 no.1
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• pp.107-115
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• 1981

The purpose of this investigation was to study histopathological chronology and differences of the proprietary pulpcapping agents. One hundred eighty molars from thrity rats (Srague-Dawley species), weighing about 130gm, were divided into six groups. Cavities were prepared in their maxillary molars under intraperitoneal anesthesia with Secobarbital. The cavities in the right first and second molars were filled with Dycal$^{(R)}$ and the left ones were with Cavitec$^{(R)}$. Each group of rats were sacrificed at the intervals of 1, 3, 5, 7, 14 and 21 days following operation. The rats were decapituated, and the jaws were fixed in 10% neutral buffered formalin. Then the specimens were decalcified, embedded in paraffin or celloid, and sectioned at 6-8 ${\mu}$ in thickness through the cavities included and pulp mesiodistally. They were stained with Hematoxylin-Eosin and examined by lightmicroscope. The results were as follow: 1. The pattern of pulp healing was dependent upon the presence and character of the pulpcapping agents above. 2. Dentin bridge formation as a sign of pulp healing occurred in the 14 days after operation. 3. Dycal$^{(R)}$ reparation appeared to favor pulp bealing rather than Cavitec$^{(R)}$ preparation. 4. In the odontoblastic layer and pulp tissue specific vaculoes were showed at the 3, 5 and 7 days of the Dycal filling.

• Restorative Dentistry and Endodontics
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• v.4 no.1
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• pp.11-16
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• 1978

This experimental study was made to investigate the effect of the "Hi-Pol" composite resin on the human dental pulp. 38 cavities of healthy permanent teeth were divided into 5 groups which were used as experimental materials. Group 1: Zinc Oxide-Euginol paste was applied to the cavities as controls $\cdots\;\cdots8$ cases Group 2: "Hi-Pol"*filling with Dycal** base $\cdots\;\cdots9$ cases Group 3: "Hi-Pol" filling without Dycal base $\cdots\;\cdots9$ cases Groud 4: Adaptic*** filling with Dycal base $\cdots\;\cdots6$ cases Group 5: Adaptic filling without Dycal base $\cdots\;\cdots6$ cases The treated teeth were extracted after 1 week, 2 weeks, 3 weeks and 4 weeks and processed for histological study. The results obtained from this experimental study were as follows; 1. The controls applied zinc oxide-eugenol showed the minimal pulp response and group 3 and group 5 showed the most severe pulp response. 2. In group 3 and group 5, the severity of pulp response increased in intensity according to the time elapsed. 3. In group 2 and group 4, the mild pulp response was found in earlier stage and the repairing process could be observed in later stage. * Boo-Pyung Co., Korea ** L. D. Caulk Co., Milford, Del. 19963 *** Johnson and Johnson Co., New Brunswick, NJ 08903.