• 펄프종이기술
• /
• 제32권4호
• /
• pp.34-40
• /
• 2000

This study was carried out to evaluate the effects of enzymatic treatment on the characteristics of KOCC. Novozym 342 and Pulpzyme HC were used for this purpose. Enzymatic treatment greatly increased the freeness of KOCC and Novozym 342 was more effective. WRV was improved only when KOCC was treated with 0.1% Pulpzyme HC. Pulpzyme HC was more effective to improve the flexibility of fiber(conformability angle) than Novozym 342. Coarseness of fiber was decreased with the enzymatic treatment. Fines content greatly decreased with 0.01% addition of enzymes. Novozym 342 was more effective than Pulpzyme HC for this purpose. Apparent density, tensile index and tear index decreased with enzymatic treatment, but stiffness increased. Especially the decrease of apparent density, tensile index and tear index by the treatment with Novozym 342 was significant than those of Pulpzyme HC. Therefore Novozym 342 will be suitable for the removal of fines and for bulky sheet, otherwise Pulpzyme HC will be good.

• Geomechanics and Engineering
• /
• 제3권2호
• /
• pp.83-108
• /
• 2011

The effect of non-plastic fines (silt) on liquefaction and pore pressure generation characteristics of saturated sands was studied through undrained stress controlled cyclic triaxial tests using cylindrical specimens of size 50 mm diameter and height 100 mm at different cyclic stress ratios and at a frequency of 0.1 Hz. The tests were carried out in the laboratory adopting various measures of sample density through various approaches namely gross void ratio approach, relative density approach, sand skeleton void ratio approach, and interfine void ratio approach. The limiting silt content and the relative density of a specimen were found to influence the undrained cyclic response of sand-silt mixtures to a great extent. Undrained cyclic response was observed to be independent of silt content at very high relative densities. However, the presence of fines significantly influenced this response of loose to medium dense specimens. Combined analyses of cyclic resistance have been done using the entire data collected from all the approaches.

• Advances in concrete construction
• /
• 제10권2호
• /
• pp.161-169
• /
• 2020

This paper studies the influence of silica fume and Processed Quarry Fines (PQF) on the flexural behaviour of the reinforced concrete beams by experimental as well as numerical studies. The study has been shown that the incorporation of PQF can significantly increase the stiffness and the flexural strength of reinforced HPC beams. Also, the ultimate strength of specimens prepared with the 10% silica fume and 100% PQF are higher compared to conventional reinforced concrete specimen. Numerical analysis is performed to find the ultimate strength of HPC beams to compare with experimental results. Nonlinear behaviour of steel reinforcing bars and plain concrete is simulated using appropriate constitutive models and experimental results. The results indicate that the ultimate strength, deformed shape and crack patterns of reinforced HPC beams obtained through the Finite Element Analysis (FEA) are confirming with the experimental results.

• 펄프종이기술
• /
• 제30권3호
• /
• pp.7-14
• /
• 1998

It is well known that the recycling of pulp generates a lot of fines, and cause the hornification of fiber. Both phenomena have been contributed to a limited use of recycled fiber. Among several means which can improve the properties of recycled fiber, enzymatic treatments are considered as an effective means. Thus the effects of xylanase on the properties of recycled pulp were investigated in this study Xylanase treatment showed some refining effect at a small dosage while the fines and fibrils were reduced at higher dosage as shown in the treatment with cellulase-hemicellulase. The interesting finding is that the WRV of recycled fiber treated with xylanase was higher than that treated with the mixture of cellulase and hemicellulase. Breaking length and tear index of recycled fiber treated with xylanase were also higher.

• 한국펄프종이공학회:학술대회논문집
• /
• 한국펄프종이공학회 1999년도 추계학술발표논문집
• /
• pp.227-233
• /
• 1999

• 한국도로학회:학술대회논문집
• /
• 한국도로학회 2008년도 추계학술대회 논문집
• /
• pp.223-226
• /
• 2008

• 펄프종이기술
• /
• 제30권2호
• /
• pp.47-54
• /
• 1998

Refining is one of the most important processes of fiber treatment that provides optical and physical properties of final paper products. The evaluation method of refining progress is usually freeness (CSF) or wetness (SR) test because of its rapidity and convenience. However, there are some deficiencies in using freeness or wetness test to evaluate pulp fibers accurately because its results are more influenced by fines contents than extent of fibers treatment. The objective of this study is to show the deficiency of wetness in evaluating the refining process. For this, beating is done by varying the beating load. Handsheets are made after beating until 25 and $32^{\circ}C$ SR, and then paper properties are measured. Refined fibers are analyzed by fiber length, fines contents, curl, kink, WRV, and zero-span tensile strength. The results show that longer beating time is required to reach the same wetness at lower beating load. There are differences in the average fiber length, distribution curve of fiber length, fines contents, curl, kink, WRV of long fiber fraction, drainage time, and zero-span tensile strength of rewetted sample at different beating load. At the low beating load in the same wetness, apparent density, breaking length, burst strength, and tear strength are higher, while opacity and air permeability are lower than those of the high beating load. Using Page s equation, which shows the relationship among tensile strength, intrinsic fiber strength, and interfiber bonding strength, interfiber bonding strength is calculated and analyzed to explain final paper properties. At $25^{\circ}C$ SR, interfiber bonding strength is only slightly higher at 2.5kgf beating load, while the intrinsic fiber strength is substantially higher. At $32^{\circ}C$ SR, intrinsic fiber strength is a little bit higher at 2.5kgf beating load, and interfiber bonding strength is remarkably higher than those of 5.6kgf beating load. These results can be used to explain the different properties of the final paper at selected beating loads.

• 임산에너지
• /
• 제22권2호
• /
• pp.54-59
• /
• 2003

최근 들어 북미와 유럽에서는 고밀화한 목질펠릿연료가 재생가능하며 카본뉴트럴한 바이오매스 에너지로서 널리 사용되고 있다. 본 연구에서는 현사시 톱밥의 고밀화를 통한 고형연료화에 관하여 연구하였다. 현사시 품종의 연료적 가치를 평가하기 위하여 열량 및 원소 분석을 수행하였다. 고밀화를 위하여 열압공정을 채택하였으며, 압밀화는 100∼180℃, 250∼1000 kgf/㎠, 2.5∼10분의 조건으로 행하였다. 고밀화연료의 특성은 밀도와 미세분 발생량으로 평가하였다. 목표치로서 고밀화연료의 전건밀도는 1.2 g/㎠ 이상, 5분간 진탕 후의 미세분 발생량은 0.5% 이하로 설정하였다. 목표 밀도와 목표미세분을 만족하기 위해서는 160℃ 이상의 압체온도가 요구되었다. 이 때의 압체압력은 750 kgf/㎠ 이상이 효과적이었다 180℃에서 1000 kgf/㎠으로 5분 이상의 압체가 고밀화연료 제조에 가장 적절한 조건으로 밝혀졌다.

• 임산에너지
• /
• 제21권3호
• /
• pp.59-65
• /
• 2002

최근 들어, 북미와 유럽에서는 바이오매스로부터 제조한 고밀화연료가 재생가능하며 청정한 바이오에너지로서 널리 사용되고 있다. 고밀화연료를 얻기 위한 현사시(Populus tomentiglandulosa)와 수원포플러(Populus davidiana) 톱밥의 압밀화에 대하여 연구하였다. 이들 수종의 연료적 가치를 평가하기 위하여 열량 및 원소분석을 하였다. 고밀화를 위해 전분접착제를 첨가한 열압공정을 채택하였으며, 압밀화는 120-l60℃에서 50kgf/㎠ 압력으로 소정시간(정확한 시간?) 시행하였다. 고밀화연료의 특성은 비중, 압축강도 및 미세분 발생량으로 평가하였다. 유접착제 공정에서는 160℃에서 7.5분 이상의 열압에 의해 미세분 발생량이 5% 미만인 고밀화연료를 얻을 수 있었다. 한편, 열압조건과 톱밥의 함수율을 조절함으로써, 무접착제 조건에서도 미세분 발생량이 5% 미만의 고밀화연료를 얻을 수 있음이 밝혀졌다.

• 한국지진공학회논문집
• /
• 제28권1호
• /
• pp.33-39
• /
• 2024

Understanding the behavior of soil under cyclic loading conditions is essential for assessing its response to seismic events and potential liquefaction. This study investigates the effect of non-plastic fines content (FC) on excess pore pressure generation in medium-density sand-silt mixtures subjected to strain-controlled cyclic direct simple shear (CDSS) tests. The investigation is conducted by analyzing excess pore pressure (EPP) ratios and the number of cycles to liquefaction (Ncyc-liq) under varying shear strain levels and FC values. The study uses Jumunjin sand and silica silt with FC values ranging from 0% to 40% and shear strain levels of 0.1%, 0.2%, 0.5%, and 1.0%. The findings indicate that the EPP ratio increases rapidly during loading cycles, with higher shear strain levels generating more EPP and requiring fewer cycles to reach liquefaction. At 1.0% and 0.5% shear strain levels, FC has a limited effect on Ncyc-liq. However, at a lower shear strain level of 0.2%, increasing FC from 0 to 10% reduces Ncyc-liq from 42 to 27, and as FC increases further, Ncyc-liq also increases. In summary, this study provides valuable insights into the behavior of soil under cyclic loading conditions. It highlights the significance of shear strain levels and FC values in excess pore pressure generation and liquefaction susceptibility.