• 한국염색가공학회지
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• 제11권1호
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• pp.34-41
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• 1999

To examine the increase of paper strength by solvent-bonding using N-methylmorpholine N-oxide (NMMO), a paper was treated with aqueous solutions of NMMO, concentrated at $90^\circ{C}$ for selected periods of time, and pressed for 5 seconds followed by washing and drying. The effect of the increasing NMMO concentration on bonding state and some important properties of samples were mainly investigated. With increasing concentration of NMMO, the degree of bonding between fibers was increased, the fiber cross-sectional shape was changed from 'thin ribbonlike' to 'round rodlike' by swelling with solvent, and the longitudinal waves (crimp) were introduced to fibers, hence the shrinkage, weight per unit area, and thickness of paper were increased. Consequently, the tensile strength and elongation, under standard and wet conditions, and the stiffness were increased, and the water absorption was decreased generally with increasing concentration of NMMO. The moisture regain of treated samples was lower than that of the untreated sample, because of the reduction of space between fibers. But the moisture regain was increased a little with increasing concentration of NMMO due to the fiber swelling with NMMO followed by structural relaxation.

• Journal of the Korean Wood Science and Technology
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• 제16권1호
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• pp.3-8
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• 1988

This study was carried out to examine the effect of pretreatment of veneer with aluminum sulfate solution for the manufacture of the kapur plywood on the reduction of urea resin spread. The results were as follows: 1. Specific gravities of plywoods made of the kapur veneers ranged from 0.83 to 0.84 and their moisture contents based on air dry weight showed from 10.6% to 11.4%. These met the Korean Industrial Standards. 2. In the case of dry shear strength for the 3rd class plywood, 40% reduction- spread met K S as well as normal urea resin spread. pH of the aluminum sulfate solution gave better result at pH 4.5 and pH 6 than at pH 3. For the manufacture of the 2nd class plywood, hot and cold water-wet shear strength show the best results at the following conditions; such as 20% reduction spread, pH 4.5 of aluminum sulfate solution and all veneer treatment.

• 한국염색가공학회지
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• 제27권4호
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• pp.318-326
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• 2015

A pre-treatment process is essential for getting high quality of digital textile printing(DTP). In this study, we have studied three kinds of carrageenan polymer(k-, ${\lambda}$-, i-Carrageenan) as a pre-treatment thickening agent for the first time. Alginate polymer was also examined and its results were compared with that of the three kinds of carrageenan polymer. To confirm the performance of each thickening agent, we examined for a sharpness, color strength and fastness(washing, rub, light). The result showed that ${\lambda}$-Carrageenan has superior property in sharpness with low viscosity and i-Carrageenan was excellent in the color strength among the pre-treatment agents. Washing fastness to color change and staining for the all samples were 4 or 4-5 grade. Both dry and wet rubbing fastness of the samples were 4-5 grade. However, ${\lambda}$-Carrageenan coated sample has the lowest grade in light fastness. As a result, we found the possibility of carrageenan polymer as pre-treatment agent.

• KSBB Journal
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• 제8권3호
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• pp.237-242
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• 1993

Chitin 섬유는 인장강도가 기대치 보다 약하며 생 체조직 내에서 흡수도가 너무 빨라 수술 후 2주일 정도의 강도 유지밖에 못하는 단점 등이 었으므로, chitin과 그 구조가 비슷한 cellulose와 혼합하여 인 장력과 유연성이 크게 증대된 Chitulose 섬유를 개 발하였다. 우선 chitin과 cellulose가 잘 용해되어 혼 합펼 수 있는 용매로서 DMAc/LiCl을 탐색하였으며 이 용애계에 용해시킨 Chitulose 용액을 가지고 습 식방사하여 얻은 Chitulose 섬유 중, 용매에 대한 chitin cellulose 함량비가 1.5: 0.2얼 때, Instron 시험결과 강도와 유연성이 가장 좋았으며, 멸균시 autoclave해도 변화되지 않아 열에 매우 안정한 것 으로 나타났다. 이 섬유를 가지고 400-500g되는 백서의 피하조직에 매몰시킨 후, 생체 내 분해흡수 도를 관찰한 결과, 매볼 후 14일부터 분해되기 시작 하여 40일 후에는 완전히 분해흡수되였다.

• 펄프종이기술
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• 제44권4호
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• pp.91-98
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• 2012

This study was carried out in order to evaluate the effects of ultra fine precipitated calcium carbonate (UFPCC) on properties of coating color, coated paper and off-set printability. It was found that blending of UFPCC increased the low-shear viscosity and water retention of coating color. The smaller the particle size, the more significant the effect of it. When the blending ratio of UFPCC was increased, brightness, whiteness and opacity of the coated paper were improved, while paper gloss was decreased due to the increase in roughness. When the UFPCC with the average particle size of $0.12{\mu}m$ was used, the ink receptivity during off-set printing was improved while print gloss was maintained or a little decreased. It was also observed that the dry-pick and wet-pick strength of coated paper were improved by the use of UFPCC. In conclusion, it is possible to produce the low gloss matt paper with the use of UFPCC since it could improve the optical properties and ink receptivity of coated paper.

• 드라이브 ㆍ 컨트롤
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• 제14권4호
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• pp.71-78
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• 2017

The power train of hydro-mechanical continuously variable transmission (HMCVT) for 8-ton class forklift includes hydro-static units, hydraulic multi-wet disc brake & clutches and complex helical & planetary gears. The helical & planetary gears are key components of HMCVT's power train wherein strength problems are the main concerns including gear bending stress, gear compressive stress, and scoring failure. Many failures in power train gears of HMCVT are due to the insufficient gear strength and resonance problems caused by major excitation forces, such as gear transmission error of mating gear fair in the transmission. In this study, wherein excitation frequencies are the gear tooth passing frequencies of the mating gears, a Campbell diagram is used to calculate the power train gears' critical speeds. Mode shapes and natural frequencies of the power train gears are calculated by CATIA V5. These are used to predict resonance failures by comparing the actual working speed range with the critical speeds due to the gear transmission errors of HMCVT's power train gears.

• Steel and Composite Structures
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• 제32권1호
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• pp.127-139
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• 2019

Bridges, offshore oil platforms and other infrastructures usually require at some point in their service life rehabilitation for reasons such as aging and corrosion. This study explores the application of adhesively bonded CFRP patches in repair of corroded circular hollow sectional (CHS) steel beams. An experimental program involving three-point bending tests was conducted on intact, corroded, and repaired CHS beams. Meso-scale finite element (FE) models of the tested beams were developed and validated by the experimental results. A parametric study using the validated FE models was performed to examine the effects of different CFRP patch parameters, including patch dimensions, number of plies and stacking sequence, on efficiency of the repair system. Results indicates that the corrosion reduced elastic stiffness and flexural strength of the undamaged beam by 8.9 and 15.1%, respectively, and composite repair recovered 10.7 and 18.9% of those, respectively, compared to undamaged beam. These findings demonstrated the ability of CFRP patch repair to restore full bending capacity of the corroded CHS steel beam. The parametric study revealed that strength and stiffness of the repaired CHS beam can be enhanced by changing the fiber orientations of wet composite patch without increasing the quantity of repair materials.

• 한국축산식품학회지
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• 제39권4호
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• pp.576-584
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• 2019

This study was performed to evaluate the physicochemical properties of myofibrillar protein (MP) gels containing pork skin gelatin at different salt concentrations. MP gels were prepared to the different salt levels (0.15, 0.30, and 0.45 M) with or without 1.0% of pork skin gelatin. Cooking yield (CY), gel strength, shear stress were measured to determine the physical properties, and SDS-polyacrylamide gel electrophoresis, scanning electron microscopy, fourier transform infrared spectroscopy, sulfhydryl group and protein surface hydrophobicity was performed to figure out the structural changes among the proteins. The addition of gelatin into MP increased CYs and shear stress. MP at 0.45 M salt level had the highest CY and shear stress, as compared to MPs at lower salt concentrations. As the salt concentration of MP gels increased, the microstructure became the compact and wet structures, and decreased the amount of ${\alpha}-helix$/unordered structures and ${\beta}-sheet$. MP with gelatin showed a decreased amount of ${\alpha}-helix$/unordered structures and ${\beta}-sheet$ compared to MP without gelatin. The addition of gelatin to MP did not affect the sulfhydryl group, but the sulfhydryl group decreased as increased salt levels. MP mixtures containing gelatin showed a higher hydrophobicity value than those without gelatin, regardless of salt concentration. Based on these results, the addition of gelatin increased viscosity of raw meat batter and CY of MP gels for the application to low salt meat products.

• 한국정밀공학회지
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• 제13권12호
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• pp.38-45
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• 1996

A new grinding wheel was developed for the high performance grinding of difficult-to-grinding materials. The grinding performance of the newly developed wheel including grinding forces, grinding ratio, and surface roughness of ground surface was evaluated through experiments. Experimental results show that the performance of the newly developed wheel is superior to the conventional alumina wheel and comparable to the Sol-gel wheel. An experimental investigation on the wear of alumina grinding wheel was also carried out. The experiments consist of the measurements of fracture strength of the abrasive grains, grinding force, and the area of wear flats of grinding wheels. Microscopic examination of abrasive grains was executed to observe the progress of wheel wear. The results indicate that the 32A grain, which has relatively lower fracture strength, wears out faster than 5SS and 5SG. The wheel wear occurs much faster in wet grinding than in dry grinding. It has also been found that the grinding forces increase logarithmically with increasing wear flats.

• Advances in concrete construction
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• 제13권3호
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• pp.233-242
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• 2022

An attempt is made to develop an eco-friendly concrete with ground granulated blast furnace slag (GGBS) and pond ash as partial replacement materials for cement and fine aggregate, respectively without compromising the strength and durability. Sixteen concrete mixes were developed by replacing cement and fine aggregate by GGBS and pond ash, respectively in stages of 10%. The maximum replacement levels of cement and fine aggregates were 50% and 30% respectively. Experimental results revealed that the optimum percentage of GGBS and pond ash replacement levels were 30% and 20% respectively. The optimized mix was used further to study the flexural behavior and durability properties. Reinforced Concrete (RC) beams were cast and tested under a four-point bending configuration. Also, the specimens prepared from the optimized mix were subjected to alternate wet and dry cycles of acid (3.5% HCl and H₂SO₄) and sulphate (10% MgSO₄) solutions. Results show that the optimized concrete mix with GGBS and pond ash had a negligible weight loss and strength reduction.