• 펄프종이기술
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• 제32권2호
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• pp.35-39
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• 2000

Refining is very important process of fibers treatment for proper paper properties. An extent of refining is usually measured by freeness, although freeness gives complicated meanings. One of a direct way of studying the refining effects on pulp fibers is making photomicrographs of beaten fibers. The conventional microscopy like light microscopy(LM) and scanning electron microscopy(SEM) require to preserve the wet structure of pulp fibers morphologically since most of papermaking process is carried out almost entirely in water. Recently developed microscopy, especially confocal laser scanning microscopy(CLSM), offers the possibility of examining fully hydrated pulp fibers. Cross-sectional images of wet pulp fibers are also generated using optical sectioning by CLSM and image analysis in order to verify and quantify the extent of fiber wall swelling indicating the internal fibrillation. At low beating load such as 2.5 kgf, in the same freeness, breaking length is higher than that of high beating load such as 5.6 kgf. fiber wall thickness at low beating load is greater than that at high beating load. This result is accounted for the fact that internal fibrillation in the low beating load was high.

• 대한치과의사협회지
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• 제57권7호
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• pp.403-411
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• 2019

A cracked tooth is defined as an incomplete fracture initiated from the crown and extending subgingivally and usually directed mesiodistally. Cracked teeth were most frequently involved in mandibular and maxillary molars at the age of 50s. Cracks occurred mainly in nonbonded restorations such as gold and amalgam, and majority of cracks were found in intact teeth. A pulpal and periapical diagnosis is dependent on the extent of the crack and duration of the symptom. The pulp of a cracked tooth might become inflamed because of microleakage, which induces thermal sensitivity. Once the crack has extended and exposed the pulp, severe pulp and periapical pathosis will likely be present. In addition, the extended crack can cause a bony dehiscence with a resulting narrow and deep periodontal pocket. Therefore, early diagnosis of the cracked tooth and proper treatment planning are important for clinician.

• 자원리싸이클링
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• 제18권2호
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• pp.16-29
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• 2009

본고는 펄프 제지산업 폐수에 함유된 오염물질들의 특성과 생물학적 처리기술들에 대해 설명한다. 펄프 제지산업 폐수는 고농도의 생화학적 산소요구량 (BOD)과 화학적 산소요구량 (COD)을 포함하고 높은 독성을 보이며 강한 흑갈색을 띠는 것이 특징이다. 특히, 펄프의 표백공정에서 리그닌의 염소화에 의해 다이옥신, 퓨란과 같은 독성의 유기염소화합물이 형성된다는 것이 알려져있다. 이에 따라 최근 펄프 제지산업은 기존의 표백처리를 무염소공정(TCF)으로 대체하고 있다. 펄프 제지산업 폐수처리에 사용되는 모든 생물학적 기술들은 폐수와 박테리아의 접촉 메커니즘에 기반을 두고 있는데, 이것은 박테리아가 폐수 내 유기물질을 먹이로 이용하여 세포로 전환함으로써 폐수 내 BOD농도를 감소시키는 것이다. 펄프 제지산업 폐수의 생물학적 처리에서 호기성 처리와 혐기성 처리 모두 효과적인 것으로 밝혀졌다. 뿐만 아니라, 최근 곰팡이류를 이용한 생물학적 처리, 생물-응집-여과기법을 혼용한 처리 등도 폐수처리분야에 새롭게 적용되었다. 이러한 기술들로 처리된 폐수를 펄프 제지공정에 재활용함으로써 제조공정의 물소비량을 상당히 감소시킬 수 있다.

• 한국펄프종이공학회:학술대회논문집
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• 한국펄프종이공학회 1999년도 추계학술발표논문집
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• pp.194-204
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• 1999

The use of genetically cloned xylanase acquired from Bacillus strearthermophillus improves bleachability for oak kraft pulps. Combination of xylanase(X). oxygen(O), ozone(Z). peroxide(P), alkaline extraction(Eo. Eop), and chlorination(C/D, D) have been tested in a variety of bleaching sequences. The effectiveness of xylanase pre-treatment(XO) and post-treatment(OX) in oxygen bleaching is mainly compared. With xylanase treatment the brightness increase by 1.5-2.1% ISO in OZEP, OZEoP, OZEopP and OPZP sequences. There is only numerically difference of brightness gains between OX and XO sequences. With xylanase treatment chemical requirements for bleaching decrease by 42.6-48.6% in OC/DEoD sequence and 47.9-54.7% as active chlorine in OC/DEopD sequence at the same brightness. the reduction of bleaching chemicals is higher in XO sequence than those in OX sequence. Following xylanase treatment the viscosity increases from 11.7-12.0 mPa·s to 12.4-13.5 mPa·s and the brightness stability is considerably improved however the difference of effectiveness between XO and OX sequence is not present. Compared to tensile index vs tear index, the physical properties are similar for TCF bleaching sequences with and without xylanase treatments. However in OC/DEoD and OC/DEopD sequences the physical properties decrease with xylanase treatment. There is no difference in the physical properties between XO and OX sequences. COD, BOD and color of bleaching effluents increase slightly with xylanase treatment, however the discharge of COD end-load into environmental impact decrease.

• 한국펄프종이공학회:학술대회논문집
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• 한국펄프종이공학회 2001년도 춘계학술발표논문집
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• pp.136-143
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• 2001

• 한국펄프종이공학회:학술대회논문집
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• 한국펄프종이공학회 2004년도 추계학술발표집
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• pp.247-254
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• 2004

• Journal of the Korean Wood Science and Technology
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• 제25권2호
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• pp.100-109
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• 1997

The objectives of this study was to decrease pollutions of bleaching effluent and was to enhanced brightness of non-chlorine bleached pulps by xylanase treatments. Xylanase cloned Esherichacoli(E. coli) capable of each of endo, exo-xylanase and acetyl-esterase were obtained from Bacillus stearothermophillus. These xylanase was maintained high activity in alkali and high temperature. Especially endo-xylanase would be more active in $60^{\circ}C$ and pH 11. Xylanase pretreatment(X) of unbleached pulp increased brightness, and decreased the degree of delignification. The degree of increase in brightness of pulp due to xylanase pretreatment was similar to non-enzyme treated pulp, regardless of the amount of enzyme added. Therefore, the addition of xylanase of 2 unit was recommended when considering costs of enzyme. The pulp bleached XO sequence had higher brightness and lower Kappa no, than O bleached pulp, while pulp bleached XP sequence had similar brightness and Kappa no. with P bleached pulp. In XOC/D, XOZ and XOP bleaching sequences, brightness and degree of delignification were improved. The C/D and Z stage bleached pulp was good effect on rate of raise in brightness and Kappa no., but P stage bleached pulp had similar level in non-enzyme treated bleaching sequence.

• 펄프종이기술
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• 제32권4호
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• pp.74-80
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• 2000

A series of studies on nitric-acid pulping of municipal recycled waste papers were carried out to substitute the bleached chemical pulp imported for producing printing paper as well as to use its solidified spent-liquor as fertilizer. The first experiment was carried out to find the optimum treatment conditions such as pulp consistency, nitric acid charge and temperature in $HNO_3$-alkali pulping process. The results obtained were as follows: 1. Some selective delignification of OCC pulp was conducted by $HNO_3$-alkali process. The higher the temperature and concentration of nitric acid, the lower the pulp yield and kappa number of treated pulp. while its brightness was increased. 2. The higher consistency required the stronger mixing in case of more than 5% pulp. 3. In the laboratory, the suitable $HNO_3$-treating condition seemed to be less than 6% consistency, lower than 500% $HNO_3$charge on pulp and lower than $100^{\circ}C$ in cooking temperature. 4. The spent liquor with 1.77% N-content seemed to be slow-release nitrogen fertilizer suitable for agriculture.

• 펄프종이기술
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• 제35권1호
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• pp.1-6
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• 2003

This study was carried out to investigate the effect of internal fibrillation on the pulp and paper properties. The internal fibrillation was introduced into the SwBKP and recycled SwBKP by the mechanical treatment with Hobart mixer. WRV and physical properties of SwBKP were improved by the internal fibrillation. However the mechanical treatment of recycled SwBKP resulted in the decrease of strength properties of paper except for the tear index, although it was observed that WRV was somewhat increased by the mechanical treatment. The decrease of strength properties of recycled SwBKP might be caused by the hornification of fiber and the decrease of fiber strength.

• 펄프종이기술
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• 제31권4호
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• pp.23-29
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• 1999

The effect of dilute sulfuric acid treatment was examined to improve recyclability of coated brokes. Turbidity , electric conductivity , and cationic demand of the white water from coated broke prepared from an alkaline base paper was determined. Sulfuric acid treatment was found to be effective in dissolving undisintegrated substances such as binders, pigments, and fibers. The properties of papers prepared by adding the broke to pulp stock up to 30% dry weight were examined . With the increase of broke addition, retention, sizing degree and smoothness were improved ; on the other hand, formation uniformness, air permeability and internal bonding strength were decreased. The extent of improvement by broke addition was greater for the surfuric acid-treated broke than the control broke. It was concluded that the use of coated broke should be limited within 10-15% weight of the product for either type of broke.