• Journal of Labour Economics
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• v.29 no.2
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• pp.117-143
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• 2006

This paper illuminates the patterns of growth and declines in sizes of union membership in metal, chemical, financial, and auto transport sectors in three distinct periods during the last four decades from 1963 to 2003. This paper also calculates union densities in auto assembly, auto supply, and shipbuilding industries of the metal sector, cement, petroleum refining, and pharmaceutical industries of the chemical sector, private banking industry of the financial sector, and city bus industry of the auto transport sector. Such diversities in both sizes of union membership and union densities among sectors and industries turned out to be associated with attitudes and choices of employers and unions in interaction with sector- and industry-specific economic (growth stage and path), institutional (degrees of government intervention), and social (demographic features of employees and prevailing sizes of firms) environment. Such finding shows that theoretical reasonings on sizes of union membership and union densities across sectors and industries in advanced nations are also relevantly useful to analyze the Korean case.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.36 no.5 s.108
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• pp.44-52
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• 2004

It is well known that Korean traditional Hanji have lots of predominant physical and optical properties such as high density, high air permeability, long lasting quality and lightness. The paper-making raw materials of traditional Korean Hanji are the bast fibre cooked from the Korean paper mulberry as a fibrous materials and sticky aqueous material from the root of Hibiscus anihot L. as additives for good dispersion of stock. Additionally, the mechanical properties of Hanji varies according to the cooking methods of bast tissues of Korean paper mulberry, the treatment methods of fibrous raw materials such as bleaching and refining, the wet formation types of sheet-making such as 'Oebal-chiji' and 'Ssangbal-choji', and the finishing treatment like stamping. This study was carried out to investigate and evaluate the quality properties of Korean traditional hand-made Hanji, and compared with commercial machine-made paper and modified prepared sheets. The physical quality comparisons of different kinds of Hanji were focused on the methods of hand-sheet making, the types of raw materials, the treatment of stamping, and the properties of ink reception and spreading.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.33 no.2
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• pp.32-40
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• 2001

It is desirable to reduce the amounts of fresh water and reuse the recycled water in papermaking process. In an attempt to improve the efficiency of recycling water refining treatment and to enhance the productivity of OCC recycling mill, up flow anaerobic sludge blanket(UASB) reactor was developed and introduced to Korea recently. In order to maximize the operating efficiency and minimize the adverse side effects it is imperative to estimate and evaluate the total effects of new system, UASB on the whole OCC recycling process. This study was carried out with a view to investigate the effects of the high temperature and alkalinity of process water on the quality ad productivity of testliner of OCC recycling mill which is equipped with UASB reactor and almost closed. Another object of this study was searching for the best available use of UASB treated process water. The results were as follows; Reuse of UASB treated water characterized with high temp and alkalinity was useful to improve the strength and drainage properties of recycled OCC owing to its good points of promoting OCC disintegration and reducing the calcium hardness of process water. However, it might not be avoidable to induce the increase of dissolved solids in process water in accordance with direct introducing of UASB treated water into the former stage of OCC stock preparation. So it would be advisable to adopt the UASB treated water in the stage of clean, screened OCC stock.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.45 no.5
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• pp.44-48
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• 2013

Ultrasonic treatment of KOCC was tried to explore the possibility for improvement of KOCC quality as a raw material for making industrial packaging paper and paperboard. The effect of pH, stock consistencies and treatment times on the ultrasonic response of KOCC were investigated. WRV, apparent density, tensile index and burst index were improved as pH of KOCC slurry is increased. However highest tear index and stiffness were obtained at pH 8. It was also found that the highest WRV and strength properties could be obtained at 0.5% of KOCC consistency during ultrasonic treatment. WRV and most strength properties were improved with ultrasonic treatment time. It was found that ultrasonic treatment can be used as a useful mean for KOCC modificaton.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.30 no.2
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• pp.13-23
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• 1998

Two major cellulase components purified with sephadex G-75 and DEAE sepharose were applied to bleached kraft pulp to inverstigate the change of fiber properties. Cellulose viscosity was very sensitive to $C_x$ component treatment (more than 15% drop was observed) while being little influenced by $C_1$, component (only 2% drop). Fiber fraction longer than 2mm was reduced by $C_x$ treatment while short fiber fraction was increased greatly by more than 15%. There was little change in fiber length distribution by combined treatment of $C_1$ 1 and $C_x$ at equal. In this case, fine contents increased by more than 2.5% at equivalent refining time. WRV and Density were increased as the amount of $C_1$ or $C_x$ treatment was increased. $C_{x}$ was main cause for increasing them. But the effect fell as enzyme dosage.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.42 no.3
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• pp.50-57
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• 2010

A mill trial was performed in a kraft paper mill in order to evaluate the possibility of utilizing dual polymer dry strength aids system consisting of cationic PVAm and anionic PAM. It was found that the cationic PVAm - anionic PAM dry strength additives can improve paper strength without significantly disturbing the stability of the kraft papermaking process when virgin UKP was used as a furnish. Tensile strength (25.3% in machine direction, 48.4% in cross machine direction), elongation of paper (31.6%, 15.6%) and tensile energy absorption (48%, 54%) were improved. Air permeability of the kraft paper was improved as well (22%). Tear strength was decreased with PVAm dry strength aids system, but it can be compensated with decreasing refining degree. In addition, the mill trial results indicate that highly air permeable kraft sack paper can be produced by the addition of PVAm dry strength agents at the stock with reduced freeness.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.39 no.4
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• pp.7-13
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• 2007

Effects of pulp type, refining and filler type on the pore characteristics and physical properties of paper were investigated. HwBKP, SwBKP and BCTMP are used to study the effect of pulp type in this study. The effects of each filler (PCC, GCC and talc) and the combination of PCC/GCC were also studied. Highest bulk, pore volume and light scattering are obtained from BCTMP and PCC. It was found that the pore size and pore volume are important in light scattering in paper structure. It was found that PCC was the most effective filler for the improvement of the bulk and light scattering because of the increase in pore volume which can scatter light, but the increase of PCC content was not so effective in the improvement of bulk.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.47 no.5
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• pp.104-111
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• 2015

Factors influencing penetration of PVAm solution into paper during impregnation were investigated with ultrasonic Penetration Evenness Analyzer (PEA). Paper structure was varied by changing basis weight, freeness of pulp, calendering, and filler addition, and hydrophobicity of paper was varied by adding AKD. In addition, the viscosity of PVAm solution was varied by changing the concentration of PVAm solution. Important factors influencing penetration of PVAm solution into paper were found to be the pore structure and the hydrophobicity of paper, and the viscosity of PVAm solution. Pore structure of paper could be controlled by refining degree and filler addition and hydrophobicity of paper could be controlled by internal sizing. Denser structure of paper, higher hydrophobicity and higher liquid viscosity slowed down the penetration of PVAm solution into paper.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.46 no.6
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• pp.8-15
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• 2014

The increase of wet web solid content in wet pressing will save drying energy greatly. We applied wood flours as spacers to increase the old corrugated container (OCC) solid contents in wet pressing. The mixed furnish of OCC and wood flours of 3-5% (wt/wt) increased bulk and drainage rate, and by increasing wet pressing pressure, its solid content started to be higher than 100% OCC furnish at more than 50% solid content level. Addition of cationic starch and drainage aid to the mixed furnish increased solid content further up to around 2%. Cationic starch addition compensated or exceeded the loss of tensile and compressive strength caused by the addition of wood flour, but drainage aid did not. Cationic starch also improved the stretch of the OCC, which could mitigate cracking at folding in boxboard.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.39 no.1 s.119
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• pp.1-7
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• 2007

Internal fibrillation of pulp fiber is an important factor affecting paper properties. Internal fibrillation of pulp fiber is usually introduced with several kinds of modifications of fiber by the mechanical treatment such as refining, high shear and/or high consistency mixing, etc. Unfortunately there are no standardized methods that can characterize the extent of internal fibrillation and its contribution on the paper properties. The purpose of this study is to try and find the potential methods that can characterize the internal fibrillation of pulp fiber quantitatively. Softwood bleached kraft pulp was treated with Hobart mixer to introduce the internal fibrillation without the significant fiber damage and external fibrillation. The extent of internal fibrillation was increased with the increase of mechanical treatment consistency. Several fiber properties were measured to find the potential means that could characterize and quantity the internal fibrillation. Laminated area could not be used as a means for quantifying the internal fibrillation because of the effect of swelling and the different internal fibrillation behavior at different mechanical treatment consistency. Micro and macro internal fibrillation models were proposed for describing the different behavior for the mechanical treatment at low and high consistencies of pulp. The Internal fibrillation showed good correlation with swelling of fiber wall. This trend was confirmed through the measurement of wall thickness and/or cross section area of fiber. Therefore the internal fibrillation possibly can be described as the indices indicating the change of wall thickness and/or cross section area.