• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 2001.11a
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• pp.183-199
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• 2001

Alternative way of shaping fibers suitable for papermaking was introduced. Impact refining, which was done simply by hitting wet fibers with a metal weight vertically, was intended to keep the fibers from shortening and to cause mostly internal fibrillation. Virgin chemical pulp, its recycled one and OCC were used in the experiment. It was noticed from the experiment that impact refining on virgin chemical pulp kept the fiber length and Increased bonding properties greatly, However, in the recycled fibers from the chemical pulp, fiber length and bonding properties were decreased. In OCC, which seems to contain fractions of semi-chemical pulp and mechanical pulp (GP), and which is recycled pulp from corrugated boxes, fiber length and bonding properties were decreased disastrously. We believe recycled cellulosic fibers (recycled chemical pulp and OCC in this case), which went through hornification, were less resistant to the mechanical impact than virgin chemical pulp. For virgin chemical pulp, impact refining allowed no significant fiber length shortening, high WRV, and high mechanical strength.

• The Journal of the Korean dental association
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• v.54 no.8
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• pp.658-665
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• 2016

Treatment of immature permanent teeth with irreversibly damaged pulp has been challenging in dental practice because of the lack of apical constriction, thin dentinal walls, and short roots. This may lead to the extrusion of filling materials, and fracture of the root due to its more fragile feature during shaping of the root canal. Apexification with calcium hydroxide or MTA is one of the treatment options for these cases. Although favorable results of apexification have been reported, these treatment procedures do not guarantee the increase of root length and/or width even after a long term period. Thus, treated teeth are still prone to fractures. Recently, pulp revascularization has been proposed as an alternative treatment for immature teeth with necrotic pulp and periapical pathosis. Pulp revascularization allows the stimulation of the apical development and the root maturation. There have been many treatment protocols using various materials such as antibiotics and calcium hydroxide medicament. In this case report, literature review about pulp revascularization and two related cases are presented.

• Proceedings of the KIEE Conference
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• 2003.11c
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• pp.720-723
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• 2003

Electric stimulation of teeth is used for assessing pulp vitality. Because of very high and wide range of impedance of the enamel, electric pulp testers use high voltage, high output impedance and alternative current source. Most pulp testers use voltage stimulation method and their stimulating threshold levels significantly depend on each individual. Therefore, a constant current stimulator is necessary to minimize the effect of wide variation in enamel thickness. In this study, we constructed a constant current source type of pulp tester with the maximum current of 150 uA.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 2006.06b
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• pp.285-290
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• 2006

As an alternative method to solve air pollution problem and difficulty of pulp bleaching of kraft pulping process, NaOH-Urea pulping was applied. The properties of NaOH-Urea pulp were compared to those of NaOH and kraft pulps. Addition of urea in low alkali charges retarded delignification rate compared to NaOH pulping. But, in high alkali application, delignification was significantly enhanced not from the addition of urea but from the high alkalinity. It was disclosed that urea did not participate on delignification reaction by the experiment using lignin model compound. Compared to paper strengths at the same level of sheet density, NaOH-Urea pulp gave as almost same breaking length and tensile index as those of kraft pulp. Especially tensile energy absorption and burst index were higher than those of kraft pulp.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.34 no.5
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• pp.56-62
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• 2002

Alternative way of shaping fibers suitable for papermaking was introduced. Impact refining, which was done simply by hitting wet fibers with a metal weight vertically, was intended to keep the fibers from shortening and to cause mostly internal fibrillation. Virgin chemical pulp, its recycled one and OCC were used in the experiment. It was noticed from the experiment that impact refining on virgin chemical pulp kept the fiber length and increased bonding properties greatly. However, in the recycled fibers from the chemical pulp, fiber length and bonding properties were decreased. In OCC, which seems to contain fractions of semi-chemical pulp and mechanical pulp (GP), and which is recycled pulp from corrugated boxes, fiber length and bonding properties were decreased disastrously. We believe recycled cellulosic fibers (recycled chemical pulp and OCC in this case), which went through hornification, were less resistant to the mechanical impact than virgin chemical pulp. For virgin chemical pulp, impact refining allowed no significant fiber length shortening, high WRV, and high mechanical strength.

• Restorative Dentistry and Endodontics
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• v.44 no.4
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• pp.35.1-35.10
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• 2019

Pulp revascularization is an alternative treatment in immature traumatized teeth with necrotic pulp. However, this procedure has not been reported in horizontal root fractures. This is a case report of a 9-year-old patient with multiple horizontal root fractures in 2 upper central incisors that were successfully treated with pulp revascularization. The patient presented for treatment 2 years after the initial trauma, and revascularization was attempted after the initial treatment with calcium hydroxide had failed. Prior to pulp revascularization, cone-beam computed tomography and autoradiograms demonstrated multiple horizontal fractures in the middle and apical thirds of the roots of the 2 affected teeth. Revascularization was performed in both teeth; platelet-rich plasma (PRP) was used in one tooth (#11) and the conventional method (blood clot) was used in the other tooth (#21). Clinical and radiographic follow-up over 4 years demonstrated pulp calcification in the PRP-treated tooth. Neither of the 2 teeth were lost, and the root canal calcification of tooth #11 was greater than that of tooth #21. This case suggests that PRP-based pulp revascularization may be an alternative for horizontal root fractures.

• Journal of the Korean Chemical Society
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• v.56 no.2
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• pp.257-263
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• 2012

The selection of suitable delignification conditions and optimization of process variables is crucial to the successful operation of chemical pulping processes. Soda pulping of Carpolobia lutea was investigated, as an alternative raw material for pulp and paper production. The process was optimized under the influence of three operational variables, namely, temperature, time and concentration of cooking liquor. Equations derived using a second - order polynomial design predicted the pulp yield and lignin dissolution with errors less than 8% and 11% respectively. The maximum variations in the pulp yield using a second order factorial design was caused by changes in both time and alkali concentration. Optimum pulp yield of 43.87% was obtained at low values of the process variables. The selectivity of lignin dissolution was independent of the working conditions, allowing quantitative estimations to be established between the pulp yield and residual lignin content within the range studied.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.39 no.5
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• pp.39-44
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• 2007

In order to utilize unsorted ONP, which contains leaflets (printed coated papers), as a raw material to produce pulp mold, optimum conditions for repulping were investigated with the pilot Helico pulper at Centre Technique du Paper (CTP), France. Two major process factors were focused: repulping concentration and rotor speed. Repulping at a higher concentration showed more rapid defibering kinetics. Increasing the rotational speed of rotor at the optimum repulping concentration accelerated the defibering kinetics while it also led to higher fines generation and faster decrease in drainage property of the produced pulp. Hence, an alternative way was suggested: starting repulping at a conventional rotor speed and then accelerating the rotor speed for the last minute(s) of repulping.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.44 no.3
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• pp.63-69
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• 2012

The rice husk is one of the major agricultural residue in KOREA. In this paper, the effects of various pulping conditions on the properties of rice husk pulp and handsheets made of rice husk fiber were evaluated in order to utilize the rice husk as an alternative source for wood pulp. Two typical alkali pulping, such as soda pulping and Kraft pulping were applied with various conditions of the pulping processes. The higher effective alkali and higher pulping temperature resulted in the higher efficiency in removal of lignin and ash, which leaded to the higher strength properties of handsheets made of rice husk fiber, but the lower yield of rice husk pulp. The better efficiency in production of rice husk pulp and the stronger handsheets were obtained by the Kraft pulping.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.43 no.5
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• pp.34-42
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• 2011

A fiber processing method, which might be an alternative for conventional refining process, was introduced. The method consists of repetitive, gentle, mechanical impacts on fibers, followed by fiber uncurling process. This method was very effective for OCC and BCTMP for increasing WRVs (water retention value) while keeping fiber lengths from shortening. For OCC and BCTMP, gentle mechanical impacts on fibers using Hobart mixer increased breaking lengths and tear strengths simultaneously at fast drainage level, and straightening fibers using kady mill increased those strength properties further. For SwBKP and HwBKP, only mechanical impacts using the Hobart mixer were effective on increasing tensile and tear strength at fast drainage, but there were no further increase by kady mill treatment. The strength increases of BCTMP by this alternative fiber processing method were exceptionally high. An extensive engineering development should be followed to actualize this fiber processing mechanism in an energy-effect way.