• Restorative Dentistry and Endodontics
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• 제19권1호
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• pp.64-72
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• 1994

Zinc Phosphate Cement hand been used for about more than 100 years in luting of cast gold inlay. But many scientists had been trying to develop the new form of luting agent because the ZPC hand shown the lack of adhesiveness on the tooth structure and the toxicity to the pulp tissue. Recently many researches about the surface treatment of the cast body are being done to increase the adhesion of cement to it. The conventional Class I gold inlays were fabricated in the 20 permanent molars. After the internal surface of the cast body was sandblasted with $Al_2O_3$ particles and was tin-plated, the inlays were cemented with adhesive cement [G I cement and resin cement(Super-Bond & $Panavia_{EX}$)] and the evaluation on the adhesion pattern, adhesive strength and the fracture pattern of the adhesive cast gold inlay was compared to that of the cast gold inlay cemented conventionally with ZPC. The results were as follows : 1. The surface roughness of the cast body was increased significantly after sandblasting with the $Al_2O_3$ particles and the tin oxide layer, which was consisted of round particles, came into being. 2. The bond strength was in the order of Super-Bond, ZPC, Fuji I, $Panavia_{EX}$ group. The group cemented with Super-Bond showed statistically greater strength than the other groups(p<0.05). 3. The group cemented with ZPC was fallen apart by principal adhesion failure and that with Fuji I was by complete adhesion failure. But the group with Super-Bond showed pricncipal cohesive failure pattern and in the group with $Panavia_{EX}$, complete cohesive fracture pattern was shown and small protion of tooth structure was fractured out with cast body and the fractured surface showed the figure just as the enamel prism. 4. Various gaps were shown at the pulpal side regardless of little gap at the side walls of the cavity in all groups. Only the Super-Bond was attached to the tooth structure and the other cements were detached from both the tooth and the cast body.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1995년도 가을 학술발표회 논문집
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• pp.75-79
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• 1995

The results of an experimental study on the manufacture and the mechanical properties of fiber reinforced calcium silicates-cement composites utilizing by products (fly ash or cement sludge) for construction materials are presented in this paper. As the test results show, compressive, tensile, and flexural strength, fracture toughness of fiber reinforced calcium silicates-cement composites were improved by increasing the fly ash and fiber contents, but were decreased by increasing cement sludge contents. Somehat, especially increasing fiber contents the fracture toughness of the composites were remarkably increased. Also, the mechanical properties of the composites reinforcing alkali-resistance GF were higher than those of the composites reinforcing Samoa Pulp.

• 펄프종이기술
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• 제41권2호
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• pp.1-6
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• 2009

The purpose of this study was to investigate effects of lignocellulosic fillers made of wood powder and inorganic fillers, such as GCC and PCC, on physical properties of papers. Mechanical treatment and chemical treatment were carried out subsequently for generating lignocellulosic fillers, and then inorganic filler and wood powder were mixed together, and then mechanically treated for making lignocellulosic fillers covered with inorganic fillers. Consequently the particle size of lignocellulosic fillers was higher than that of inorganic fillers, which led to lumen loading and simultaneously surface coverage of fine inorganic fillers. Lignocellulosic fillers contributed to the increase of both bulk and opacity of handsheets dramatically, but some of properties including tensile strength, brightness and roughness decreased compared to inorganic fillers.

• 펄프종이기술
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• 제46권4호
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• pp.28-36
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• 2014

We studied the green synthesis and antibacterial activity of paper coated with chitosan-silver (Ag) green nanocomposites for packaging applications. Green synthesis of Ag nanoparticles (AgNPs) was achieved by a chemical reaction involving a mixture of chitosan-silver nitrate ($AgNO_3$) in an autoclave at 15 psi, $121^{\circ}C$, for 30 min. AgNPs and their formation in chitosan was confirmed by UV-Vis spectroscopy, transmission electron microscopy (TEM) and dynamic light scattering (DLS). As-prepared chitosan-AgNPs composite materials were coated on manila paper using Meyer rod. Surface morphology and Ag contents in coating layer were characterized by field emission scanning electron microscopy (FESEM) and energy dispersive spectroscopy (EDS). The mechanical properties such as tensile strength and elongation were significantly affected by coating with chitosan-AgNPs. The antibacterial test of coated paper was performed qualitatively and quantitatively against Escherichia coli (E. coli). It was shown to be effective in suppressing the growth of E. coli with increasing Ag contents on the surface of coated paper and more than 95 R (%) of antimicrobial rate was obtained at chitosan-AgNPs coated papers.

• 펄프종이기술
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• 제46권4호
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• pp.62-68
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• 2014

The application of conifer leave to the papermaking process as a functional organic filler was investigated in this study. The powder of the conifer leave after hot water extraction for the functional extract, such as phytoncide, was applied to OCC stock. The comparison between the commercial wood flour and the conifer leave powder as organic filler for OCC paper were conducted with various wet pressing conditions. The amount of the water removal by the wet pressing process and the bulk of handsheet were increased by the addition of the wood flour and the conifer leave powder, although the tensile strength was decreased. At the higher pressure condition of the wet pressing, the wet pressing efficiency was greatly increased by the wood flour and the conifer leave powder. There was a little difference in the performance of the wood flour and the conifer leave powder as an organic filler. Those results showed the conifer leave powder could be an alternative resource to the wood powder for papermaking organic filler.

• 한국펄프종이공학회:학술대회논문집
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• 한국펄프종이공학회 2001년도 추계학술발표논문집
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• pp.55-56
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• 2001

지난 수년간 유럽을 중심으로 Carbonate의 PSD (Particle Size Distribution)가 도공지 의 백색도, 불투명도, Coverage등에 미치는 영향에 대하여 많은 연구가 진행되어 왔다. 현재 국내의 Coating Pigment System 역시 Carbonate 위주로 구성되어 있으나, 입자 분포에 따른 실증적 연구가 선진국에 비하여 부족한 상태이다. 본 연구는 최근 유럽에서 사용 중인 Narrow PSD Carbonate가 도공지 품질에 미치는 영향을 검토한 것으로서, 특히 Multiple Coating에서의 도공층 구조변화와 그에 따른 백지물성 및 인쇄적성의 변화를 연구한 것이다. 실험의 Case는 Broad PSD CaC03와 Narrow PSD CaC03를 비 교하였 다 .. Color F Formulation은 Pre Color에서 #1 Clay 30 p따t와 각각 CaC03 70 p따t를 사용하였다. 그리고 바인더와 첨가제는 동일하게 사용하였다 .. Top color Formulation 또한 동일하 게 사용하였다. 코팅방식은 speed 450rrνmin, pre rod coating, top blade coating 방식 으로 CLC (Cy lindrical Laboratory Coater)를 사용하여 코팅하였다. 백지품질은 백색도, 평활도 ,광택도, 거칠음도, Bum Out Test와 Coverage( SEM 사 진 Z -direction) 등을 측정하였다. 인쇄품질은 인쇄 광택도, 인쇄 Picking strength와 2 도 인쇄 농도를 측정하였다. 백색도는 Narrow PSD CaC03를 사용한 것이 Broad PSD CaC03를 사용한 것 대비 약1% 우수하였다. 이것은 Narrow PSD CaC03를 사용한 것이 filter cake이 많이 open 되 어 있어 dewatering이 빠르고, Wet void volume이 증가되 어 부동화점 의 농도가 낮 아져 원지 층으로 침 투되 는 pigment가 작고 표층에 잔류하는 pigment와 void volume의 증가로 인해 기공층이 증가한 것으로 판단된다. 그리고, 백지광택도, 거칠음도 등 또한 Narrow PSD CaC03를 사용한 것이 우수하였 다. 이는 Pre color에서 coverage의 개선으로 top color층의 도공량 uniformity가 개선 된 이유라고 생각한다. 그러나 인쇄품질은 백지와 비교하여 차이가 없었다. 이것은 top 칼라 Formulation이 동일하고, 인쇄시 잉크흡수 거동은 top color 층에 주로 영향을 받기 때문이라고 판단 된다. 향후에는 인쇄품질의 향상을 위하여 Case 2의 CaC03 100% 사용가능성 및 Pre Color 는 Case 2로 고정하고, Top칼라를 변경하는 방법을 또한 생각할 필요가 있다고 판단된다.

• 펄프종이기술
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• 제46권1호
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• pp.46-55
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• 2014

In this study, we modified the surface of nanofibrillated cellulose (NFC) through LbL (Layer-by-Layer) multilayering process with polyelectrolytes and investigated the effects of the NFC modification on the charge of NFC surface and the dewatering ability of NFC suspension. The multilayering process was done onto NFC fibers using polydiallyldimethylammonium chloride (PDADMAC) and poly-sodium 4-styrene sulfonate (PSS) under different dosage and washing conditions. When the washing was carried out in every adsorption stage, the modified NFC had strong cationic or anionic charge depending on the type of polyelectrolyte in the outermost layer and the dewatering ability was not affected. In the case of no washing treatment or washing in the final adsorption stage, however, the zeta potential of NFC was close to an isoelectric point so that the dewatering ability increased remarkably. Low addition level of polyelectrolytes also showed the similar results. The mixing of NFC suspensions with opposite charge resulted in higher network strength and improved dewatering ability due to the flocculation.

• 펄프종이기술
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• 제47권1호
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• pp.10-16
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• 2015

Bio-binder is well known as a promising alternative binder for SB latex because it is eco-friendly and inexpensive, compared to synthetic latex. SB latex in top coating color was substituted with starch-based bio-binder to investigate its effects on the coating color and its coated paper properties. Bio-binder contributed to the increase of coating color viscosity, and the improvement of water retention. Most optical properties except opacity were deteriorated by the increase of bio-binder dosage. It was also found that the increase of bio-binder substitution in top coating color brought about the increase of roughness, and decrease of coated paper gloss, print gloss, dry and wet pick strength. However the stiffness and the ink set-off of the bio-binder coated paper were improved. Overall, mostly adverse effects of bio-binder on the properties of coating color and its paper were observed. Therefore, it is not recommended to use bio-binder as top coating color.

• 펄프종이기술
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• 제45권5호
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• pp.49-55
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• 2013

To explore the paper materials for restoration of the Annals of the Joseon Dyansty, durability of the three type of the traditional Korean Papers were estimated in this study, through moist heat artificial aging test. Three types(D, F, and G) which showed the best preservation performance in dry heat and UV treatment in the previous study were selected and artificial accelerated aging treatment with moist-heat process was conducted; the viscosity change rate was D>G>F; folding endurance G>D>F; $L^*$ value F>D>G; $a^*$ and $b^*$ change rate D>G>F; brightness decrease rate D>G>F, suggesting paper F showed the least change rate in physical/optical properties. Also the CLSM image observation showed fair coherence among fibers and confirmed paper mulberry. And in FDI extraction from each sample, paper F showed the highest value. Overall, paper F (traditional glossy paper) showed the highest stability against thermal treatment. It confirms that paper F is suitable as restoration paper for tributary remains including the annals of the Joseon Dynasty for its steady strength/viscosity decrease rate and color change rate.

• 펄프종이기술
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• 제45권1호
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• pp.75-82
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• 2013

The traditional Hanji-making was confronted with lots of industrial disadvantages and economic problems, due to the original hand-made process. Recently, the studies on the automation of overall Hanji manufacturing process is carried out by applying the commercial chemical pulping method in order to expand industrial application or efficiency of non-wood fibrous materials. However, the application of commercial pulping methods to the bast tissues of paper mulberry leads to the chemical and mechanical deterioration of cellulosic fibers. In this study, the optimal cooking method using the bast parts of paper mulberry produced by an auto-scraping device was applied to minimize the damage of fiber strength for the paper yarn manufacture. The pre-steaming treatment and alkaline pulping systems were evaluated in removal efficiency of lignin and pectin materials within the bast tissue of paper mulberry. With the application of pre-steaming treatment and 2 stage pulping system using potassium carbonate and then sodium hydroxide, kappa values were decreased two times more in lignin removal than the single stage of pulping method. It was also identified from SEM images and ATR-FTIR spectra that the pectin components within cellular structure of bast tissue were easily removed and the debarked bast parts by a auto-scraping device were easily defiberized by 2-stage pulping sequence using potassium carbonate/sodium hydroxide pulping system.