• 대한치과교정학회지
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• 제21권3호
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• pp.635-656
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• 1991

It was the aim of this investigation to evaluate some histologic aspect of rat pulp tissue after it had been compromised by an experimental orthodontic force. Experimental animals of thirty five Spraque-Dawley rats were employed. The first upper molars had been successively mesial moved (initial load 100 gr.) with a closed coil spring during 21 days. The experimental periods were set on immediate, 1 day, 1 week, 2 weeks, 3 weeks, 4 weeks following retention time. On each experimental period, the rats were killed and prepared for the light microscopy. After prepared with H/E stain and Gomori's one-step trichrome stain, the specimens were analyzed with evaluation criteria which were adopted in this study. The result may be summarized as follows; 1. The main pulp changes due to experimental orthodontic force included vacuolization of odontoblastic layer, circulation disturbance, root resorption, reduced pulp collagenous fiber density and mean cell count of pulp fibroblast in the immediate group. 2. The pulp tissue changes were revealed reversible because the relieved pulp tissues from experimental orthodontic force were recovered rapidly in each evaluation criteria during retention periods. 3. Compared with normal control group, pulp collagenous fiber density were decreased in immediated group (p < 0.01), but increased in each retention groups. These seem to suggest that the pulp tissues were aged after experimental orthodontic force conditions. 4. Compared with normal control group, mean cell counts of pulp fibroblasts were decreased in immediate group (p < 0.05), but increased continuous in each retention groups. These seem to indicate that the pulp tissues were highly regenerative after experimental orthodontic force conditions. 5. Compared with normal control group, root resorptions occurred in all immediate specimens (p < 0.01) and they were healed in each retention periods, but often observed in 4 weeks retention group. These seem to indicate that root resorptions were recovered slowly after experimental orthodontic force conditions.

• 펄프종이기술
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• 제29권1호
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• pp.36-42
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• 1997

비건조 화학펄프의 세포벽공 속으로 충전제의 충전을 요체로 하는 소위 섬유벽 충전기술은 제지 공정의 충전공정을 개선하는데 기여해 왔다. 섬유 세포벽 충전기술이라 함은 펄프섬유의 세포벽공에 두가지 이상의 수용성 염의 이온용액을 1차와 2차로 차례로 흡착시켜 충전제를 침착시키는 기술이다. 즉 이들 두 이온 용액의 세포벽 내에서의 화학반응에 의해 세포벽 세포벽공내에서 물에 부용의 침전을 유발케하는 공정이다. 비록 이 섬유 세포벽 충전기술이 제지공정상 비건조 화학펄프에 적용하도록 고안되었지만, 본 연 구에서는 폐지의 재활용을 위해 폐지에 이 충전기술을 시도하였다. 그 결과 무게비율로 폐지섬유의 약 5-6%와 4-5%의 CaCO$_3$와 SrCO$_3$가 각각 충전되었다. 비건조 화학펄프의 그들 값이 17-18% 와 16-18%를 나타내는 결과와 비교하여 매우 낮은 값이긴 하지만, 여전히 주목할 만한 결과로 간주되었다. 또한 이 세포벽 충전기술은 실험결과 재래의 충전방식보다 광학적 성질, 물리적 성질 및 강도적 성질이 훨씬 우수함을 보여 주었다.

• 펄프종이기술
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• 제42권2호
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• pp.67-74
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• 2010

This study was carried out to investigate the pulping and papermaking characteristics of lotus (Nelumbo nucifera G.) leafstalk for the development of high performance paper. Anatomical and chemical properties of the lotus leafstalk were analyzed. The pulping and papermaking properties of the lotus leafstalk by conventional alkali and sulfomethylated pulping processes were also evaluated. The length and width of fibers were 0.06-3.32 mm (av. 1.23 mm) and 3.47-25.6 ${\mu}m$ (av. 20.7 ${\mu}m$), respectively. The length and width of vessel elements were 0.07-0.78 mm (av. 0.20 mm) and 14.1-330.0 ${\mu}m$ (av. 54.13 ${\mu}m$), respectively. The fiber length/fiber width ratio was 60.20. The extractives (cold water, hot water, 1% NaOH and ethanol-benzene) and lignin content of lotus leafstalk were higher than those of plant bast fiber. The contents of holocellulose, lignin, and ash were 73.8%, 24.3%, and 4.3%, respectively. The pulp yields based on pulping methods were sulfomethylated pulping av. 52%, and alkaline pulping av. 42%. The conventional alkaline pulping shows better pulp and sheet properties than the sulfomethylated pulping which was modified pulping processes. But the sulfomethylated pulping shows higher brightness than alkali pulping. In the consequence of FE-SEM observation, lotus leafstalk pulp consists of various kinds of thin walled fibers which have large amount of small pits.

• 펄프종이기술
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• 제42권1호
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• pp.20-25
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• 2010

Fractionation effects of the slot-type and the hole-type screens of mutifractors were studied using a pilot multifractor. We used a slot screen of 0.15 mm, and two hole screens of 1.0 and 2.0 mm, respectively, in the study. We found hole-type screens were more effective for fractionation of fiber furnishes according to their fiber lengths. Slot-type screen was more effective to remove the shives from the accepted fiber furnishes. There existed a high regression coefficient between the fiber length differences and the freeness differences of the accepted and the rejected fiber furnishes.

• 한국펄프종이공학회:학술대회논문집
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• 한국펄프종이공학회 2006년도 PAN PACIFIC CONFERENCE vol.2
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• pp.427-431
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• 2006

Formation which is one of the most fundamental characteristic of paper quality is affected by a number of variables. Fiber flocculation in the headbox has been recognized as the most important variable influencing formation. Consistency and crowding number of headbox stock are known to represent the flocculation potential of stocks. The effects of consistency and crowding number on paper formation were studied by measuring the flocculation of fiber suspensions. Increasing consistency increased the degree of fiber flocculation. Especially the consistency of long fiber fraction was the most crucial factor of flocculation. Tensile strength of handsheets was furnish dependent rather than flocculation dependent. Crowding number of a furnish can be used for the characterization of stock flocculation.

• Journal of the Korean Wood Science and Technology
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• 제21권1호
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• pp.21-38
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• 1993

In order to investigate the influence of recycling, a laboratory method simulating the papermaking process was used for assessing the effects of recycling on fiber properties. Sw-BKP, Hw-BKP and BGP were disintegrated and beaten to about 42$^{\circ}$SR-44$^{\circ}$SR by a valley beater. After beating, these pulps were dewatered by centrifuge and dried at 90$^{\circ}C$ for 72hrs. This recycling process(sequence of wetting, defiberating, dewatering and drying) was repeated seven times. Physical, mechanical and optical properties of recycled pulps were evaluated by TAPPI Standards. Morphological changes occurred through recycling process was observed by SEM. Sheet density decreased with recycling. The largest drop in density occurred during the first recycling. The porosity values decreased with recycling. Mechanical properties such as tensile, burst strength and folding endurance, decreased with recycling. However tear strength of Sw-BKP and mixtured pulp increased at the first recycling. Optical properties such as brightness, opacity and light scattering coefficient, increased with recycling. However, brightness of mixtured pulp gradually decreased with recycling. Fibrillated outer layer of the fiber was gradually removed from the surface with recycling. As a result of recycling, crinkles on the fiber surface were found to be more folded.

• 펄프종이기술
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• 제31권4호
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• pp.84-92
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• 1999

Excellence of the Korean traditional paper(Hanji) can be proved by literatures and legacies handed down from generations. However, with the problems pertaining to a majority of traditional manufactures, Hanji industry was declined because of low productivity, insufficient supply of raw material , and reduced demand. therefore, modernizxation of the Hanji technology and development of new uses are very important. This study was carried to investigated the papermaking characteristics of Morus spp.(M.alba, M.Bombycis, and M.Ihou) for new Hanji, modernize manufacturing process of Hanji by grafting on developed modern pulping and papermaking technology, develop the various uses, and establish the foundation for development of high value-added products. Hanji is made from M.Ihou, while stalk , and sulfomethylated pulp gave better sheet formation and higher brightness than those of the others. Physical properties of Hanji which made from bast fiber pulps were better than those of whole stalk pulps. Hanji which made from M.bombycis bast fiber and whole stalk pulps were not so good sheet strength as other species. Sulfomethylated whole stalk pulps were shown better sheet strength than alkali and alkali-hydrogen peroxide whole stalk pulps.

• 펄프종이기술
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• 제43권4호
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• pp.31-39
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• 2011

One of the main drawbacks of wood fibers based composite materials are their tendency to swell due to moisture uptake in wet and moist environments. The main contribution to the hygroexpansion usually comes from the hydrophilic wood fibers. Recent trend toward the high speed printing, copying, and precision converting precesses demands a high level of dimensional stability under various environmental conditions. The purpose of this study was to investigate the dimensional stability of softwood bleached kraft pulp handsheets depending on wet pressing conditions. By increasing the number of wet pressing, dimensional stability was decreased because of increased fiber-to-fiber bonding. Hygroexpansion of handsheets had a linear relationship with the relative bonded area and equilibrium moisture contents. Dip elongation was decreased when the number of wet pressing was increased because of increased fiber-to-fiber bonding to resist low load in water.

• 펄프종이기술
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• 제41권4호
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• pp.52-57
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• 2009

Soda and kraft pulping experiments were carried out in order to investigate the pulping characteristics of bamboo grown in Vietnam. The merit of kraft pulping was not observed for bamboo pulping from the viewpoint of delignification and screened pulp yield. The improvements of delignification during soda and kraft pulping of bamboo were observed by the addition of AQ. The bamboo pulp leaded the bulkier structure than those made from SwBKP and HwBKP. The average fiber length was 1.62mm which is shorter than those of SwBKP, but longer than those of HwBKP. It was found that the physical properties of bamboo pulp sheet could be varied by the pulping method, cooking condition, AQ addition, bleaching and refining etc.

• 펄프종이기술
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• 제38권1호통권113호
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• pp.16-20
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• 2006

The effect of the freeness of pulp slurries on turbidity and transmittance of papermaking stocks was investigated using beaten bleached hardwood pulp stocks with freeness ranging from 651 mL to 403 mL CSF. Also the influence of fiber length on the turbidity and transmittance was examined with fractionated pulp stocks. Increases in stock consistency increased the turbidity. Transmittance of stock samples decreased, however, with the increase of stock consistency. Second order equations and exponential equations have been obtained as regression equations for the turbidity and transmittance of these stock samples, respectively.