• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 C
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• pp.2250-2252
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• 2005

본 논문은 HVDC용 크라프트 절연지의 기본 전기적 특성평가를 목적으로 온도별 역률의 변화, 절연저항 및 임펄스 절연파괴강도 등을 측정한 결과이다. 온도에 따른 크라프트 절연지의 역률은 $50{\sim}70^{\circ}C$에서 최소 값을 나타내었으며, 밀도가 낮은 시료일수록 낮은 역률을 나타내었다. 하지만, 임펄스 절연파괴 강도는 밀도가 낮을수록 저하되는 특성을 나타내어 적절한 밀도의 선정이 필요하다는 사실을 알았다. 또한, 온도 및 인가 전계에 따른 절연저항을 측정하여 크라프트 절연지의 온도상수 및 전계상수를 측정한 결과, 온도상수 ${\alpha}$는 $0.09{\sim}0.1^{\circ}C^{-1}$, 전계상수는 약 1.5을 얻었다. 이는 HVDC용 케이블의 설계 시 절연체의 전계분포 및 두께 산정에 기본적인 데이터를 제공할 수 있다.

• 펄프종이기술
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• 제37권3호
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• pp.66-73
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• 2005

This study was performed to understand the changes in wood extractives, mainly acetone extracts, in pine woods (Pinus densiflora and Pinus rigida) treated by three blue stain fungi (BSF) such as native BSF in Korea, Leptographium sp., screened Albino strain(BSFcs-1) and commercial Cartapip and fungicide, Wood guard. In addition their pulping and bleaching properties were investigated. BSF treatment has significantly reduced acetone extracts, $25.1{\sim}30.4%$ decreasing in red pine and $22.9{\sim}28.1%$ in pitch pine. Three week aging treatment showed about 20% decreasing in red pine and 19.3% in pitch pine. There were not so significant differences in extracts reduction among native BSF and Albino-type strains (Albino strain, BSFcs-1, and commercial Cartapip). But fungicide, Wood guard, treated wood showed relatively lower decreasing rates of extractives, 14% in red pine and 10.1% in pitch pine. Therefore it is understandable that the fungicide could protect the wood from blue stain fungi attack, but has no effect on its extractive reduction. Concerned to pulping properties of BSF and fungicide treated woods, red pine and pitch pine, optimum pulping condition was 20% active alkali, wood to liquor ratio 1 to 6, $170^{\circ}C$, and 2.5 hr. In the case of BSF woods, optimum pulping condition was same as the sound wood, $43.5{\sim}45%$ of pulp yields and $1.3{\sim}1.45%$ of rejects. Screened pulp yield of fungicide treated wood was lower than those of BSF treated woods. Rejects in pulps were higher in fungicide-treated wood than BSF treated woods. Bleaching pulp yields were ranged of 92 to 93.5%. BSF, Cartapip and fungicide treated woods resulted in lower brightness of $55{\sim}58%$, but Albino-type strain(BSFcs-1) $61.3{\sim}62.3%$, very similar to untreated one. Therefore bleaching chemicals could be saved in the processing of chemical pulping.

• 펄프종이기술
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• 제32권4호
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• pp.49-57
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• 2000

This study was carried out to investigate the effect of the type of base papers containing rice straw-BKP on the properties and printabilities of coated papers. Also, it was intended to evaluate the effect of coated paper prepared with anionic and amphoteric latex based coating color. The results obtained from this study were as follows. The fiber length of rice straw-BKP was observed much shorter than those of the wood pulps(Sw-BKP, Hw-BKP). This has effect on physical properties. Therefore, the results of measured physical properties were much lower than those of wood pulps. Also, physical properties tended to increase slightly with the increase of the mixing ratio of Sw-BKP. Opacity of the base paper containing rice straw-BKP, was higher than that of the wood pulps. As the mixing ratio of Sw-BKP increases the opacity tended to decrease. On the other hand, smoothness and roughness to rice straw-BKP were similar with Sw-BKP and its air permeability was lower than those of wood pulps. The optical properties of coated papers containing rice straw-BKP tended to be similar to those of other base papers. The ink receptivity of coated papers containg rice straw-BKP was higher than those of wood pulps and printing gloss was similar to wood pulps. The mixing ratio of Sw-BKP, the ink receptivity and printing gloss of rice straw-BKP were showed no difference irrespective the mixing ratio of Sw-BKP. Meannwhile, amphoteric latex improved the optical properties and printability of coated papers.

• 펄프종이기술
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• 제46권2호
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• pp.1-7
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• 2014

Causticizing calcium carbonate (CCC) is produced as a by-product in the causticization step of the kraft pulping process. It is often calcined in a rotary lime kiln after being dewatered and reused in the causticizing process. But for the China mill, the conventional recycled way is difficult because the CCC is mainly obtained from non-wood pulping materials, which higher silicon content led to serious silicon obstacle. So it is often discarded as solid waste or used in landfill after dewatering and secondary pollution is brought. In order to prevent its secondary pollution, recent years, the CCC is used as a filler in China papermaking industry. In mill trials, the CCC can be used to replace an amount of precipitated calcium carbonate (PCC). Unfortunately, the application scope and dosage of CCC have been limited due to its lower sizing efficiency than PCC. In this study, the reason for the lower sizing efficiency of alkyl ketene dimer (AKD) when CCC was used as a filler was investigated. The results showed that the materials in green liquid, such as insoluble matter in green liquid, silicon and metal ions, were a little influence on the sizing efficiency of AKD. The higher BET and BJH pore volume of the CCC were the main reason for lower sizing efficiency of AKD when it was used as filler.

• Journal of Forest and Environmental Science
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• 제29권1호
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• pp.1-14
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• 2013

Acacia mangium is an evergreen fast-growing tropical tree, which can grow up to 30 m tall and 50 cm thick, under favorable conditions. It is a low-elevation species associated with rain forest margins and disturbed, well-drained acid soils. It is native to Papua, Western Irian Jaya and the Maluku islands in Indonesia, Papua New Guinea and north-eastern Queensland in Australia. Due to its rapid growth and tolerance of very poor soils, A. mangium was introduced into some Asian, African and western hemisphere countries where it is used as a plantation tree. A. mangium has good quality wood traits, such as a comparatively low proportion of parenchymatous cells and vessels, white and hard wood, and high calorific value. Therefore, it is useful for a variety of purposes, such as furniture, cabinets, turnery, floors, particleboard, plywood, veneer, fence posts, firewood, and charcoal. It is also being used in pulp and paper making because it has good pulp traits, with high yields of pulp, quality of kraft, and produces paper with good optical, physical and surface properties. Because there are significant provenance differences in growth rate, stem straightness, heartwood formation and frequency of multiple leaders, the productivity and quality also varies depending upon environmental conditions, so genetic improvement programmes have been undertaken in countries like Australia, India, Indonesia, Malaysia, the Philippines, Taiwan and Thailand. The programme includes provenance identifications and testing, plus tree selection and clonal multiplication, establishment of seed orchards and hybridization. The phenology, reproductive biology, fruit characteristics, silvicultural practices for cultivation, pest and diseases problems, production of improved planting stock, harvesting, wood properties and utilization have been discussed in this paper.

• 펄프종이기술
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• 제30권2호
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• pp.5-12
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• 1998

Exploitation of the papermaking technology to reduce the strength loss that accompanies when using recycled papers as raw materials for papermaking is one of the most important issues imposed upon today's paper industry. Multi-layer sheet forming technology has been suggested as a way that provides some answers to this issue. In this study strength properties of single- and two-layer handsheets formed with recycled fiber and unbleached softwood kraft pulp have been examined to quantify the benefits when using two-layer sheet forming technology rather than a conventional single layer sheet forming precess. Single- and two-layer handsheets were made from 50% of OCC and 50% of Sw-UKP and their strength properties were evaluated. Also the strength properties made from Sw-UKP and OCC sheets were determined. A multihead, which can be attached on the top of hand- sheet former, was used to form two-layer sheets. Maximum strength properties could be obtained in the freeness range of 500∼300mL CSF for Sw-UKP Most of the strength properties was reduced by 30∼35% when 50% OCC was blended with UKP. Decrease of strength properties, however, could be reduced by employing a two-layer sheet forming method. Creator strengths could be obtained when UKP was positioned at the top layer of two layered sheets indicating greater UKP fines retention due to the filtration effect of the OCC layer formed prior to UKP layer contributed the strength improvement. Two-layer sheet showed lower Scott internal bond strength than single layer sheet. By incorporating some of UKP fibers into OCC layer this reduction could be reduced.

• 한국펄프종이공학회:학술대회논문집
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• 한국펄프종이공학회 2006년도 PAN PACIFIC CONFERENCE vol.1
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• pp.117-121
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• 2006

Virgin bleached kraft pulp, CPO (computer printout) and white ledgers are main raw materials used in tissue mills. The utilization rate of recycled fibers and virgin pulp in South Korea tissue industry are 90% and 10%, respectively. To improve brightness of printing grades the use of 'fluorescent whitening agents (FWAs)' or 'optical brightening agents (OBAs)' has been increased. When recycling these papers for tissue production, it is unavoidable that FWAs contained in recycled papers flow into tissue production lines and remain in the products. And this draws great attention from the public. This study was carried out to develop a technology for the removal of fluorescent whitening agents from recycled fibers. Enzymatic removal of FWAs was evaluated as a method to remove FWAs from the recycled fiber. The ${\alpha}-amylase$ that degrades starched used for surface sizing of fine papers and contained substantial condition is needed to prevent the re-adsorption of FWAs on fibers. The temperature of pulp suspension was another important factor affecting on FWA removal. The higher the temperature, the greater the efficiency of removing FWAs was obtained. Optimum pH and temperature for the effective removal of FWAs were suggested to be pH 8.5 and $65^{\circ}C$, respectively. The enzymatic removal of FWAs showed a great synergistic effect when proper control in pH and temperature was made.

• 한국초전도ㆍ저온공학회논문지
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• 제14권4호
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• pp.24-27
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• 2012

The measurement of the coefficient of thermal expansion (CTE) of polypropylene laminated paper (PPLP) as electric insulating material is important for its practical superconducting device application. The thermal strain induced to HTS tapes and its insulating material during cooling from room temperature might largely affect the critical current ($I_c$) of HTS tapes. In this study, the thermal contraction of PPLP material was measured during cooling from 300 K to 77 K using double extensometers. Initially, the CTE of a brass tape was measured and it was compared with a reference data. It was found that the measured thermal expansion data of the brass material approaches that of the reference one. Based on the results, it was then confirmed that the measurement technique could be applied to thin and flexible samples. Therefore, the same measurement procedure was applied to PPLP material using double extensometers. As a result, the linear CTE of the PPLP at 77 K has been measured to be ${\sim}15.3{\times}10^{-6}/K$. Also, it was found that the thermal contraction characteristics of PPLP was dominated by polypropylene on the cross direction (higher thermal contraction) while it was dominated by Kraft paper on the machine direction (lower thermal contraction). Overall, this measurement procedure could be adopted for the determination of CTE of flexible materials such as PPLP.

• 펄프종이기술
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• 제48권1호
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• pp.119-126
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• 2016

In this study, we separated the lignin from the wood by using the high boiling point solvent for developing more environmental friendly pulping method. High boiling point solvents as Ethers, glycols and ketones were used to remove the lignin in the pine wood meals. The Yield and lignin content of residual wood meals was reduced according to the input of the catalyst. Me-C, E-Ca, TEG and MIBK had the best delignification rate of 9 kinds of high-boiling point solvents. At the hydrolysis ratio of the selected solvents, The TEG was highest remain ratio of carbohydrates and the E-Ca was lowest remain ratio of lignin. And the Me-C was most excellent lignin hydrolysis ratio at the low catalyst. The selectivity of delignification of Me-C, E-Ca, TEG and MIBK solvents were 49.6, 49.9, 53.8 and 53.1%, respectively, and its values were similar to those of the commercial Kraft Pulp.

• 펄프종이기술
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• 제31권4호
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• pp.58-68
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• 1999

This experiment was to investigate decoloization characteristics of E1 effluents from the bleaching plant of pulp mill with three white-rot fungi(Trametes versicolor, Ganoderma appanatum and Pleurotus ostreatus).In addition, the effect of carbon and nitrogen resources was discussed on its decolorization. The color removal of E1 effluent during shaking and stationary cultures were 72% and 80%, respectively. Stationary culture was more effective on decolorization of E1 effluent compared to the shaking culture. The optimum inoculum weight was 1.0g based on dry weight of mycelia . The decolorization medium I showed 88% of the color removal of E1 effluent with in one day cultivation of T.versicolor and P.ostreatus . Color removal was increased from 87% to 90%. T.versicolor and P.ostreatus by the addition of 0.5% glucose. By addition of nitorgen sources(ammonium sulfate and ammonium choride), medium was much higher than that of carbon source. With 0.1% ammoniumm sulfate, P.ostreatus and T.versicolor showed 94% and 92% of the color removal within one day of cultivation , respectively. On decolorization medium II, T.versicolor and P.ostretus were 94% of oclor removal with addition of carbon source. The addition of nitrogen source was much more efficient than that of carbon source. With 0.1% amminium chloride, T.versicolor and P.ostreatus showed 95% of its color removal . The decolorization medium II was higher color removal than medium I, and also MnP and laccase were produced. However, the decolorization medium I produced a little MnP and laccase activity. It could be suggested that MnP and laccase may play an important role in decolorization of E1 effluent.