• Journal of the Korean Geosynthetics Society
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• v.15 no.4
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• pp.53-62
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• 2016

This paper presents the results of a reduced-scale physical model investigation into the effect of drilling fluid with different mix designs for use in offshore bore hole collapse prevention. Compare the bentonite and Attapulgite use. Reduced-scale model tests were then carried out considering field procedures for cases with decomposed granitic soil with fines and a sand with various drilling fluids with different mix designs. The results were indicated that the addition of polymer to the bentonite based drilling fluid decreases the amount of injected drilling fluid and increases the final depth of excavation. Also revealed that the effect of polymer on the performance of drilling fluid is more pronounced in the decomposed granite soil with fines than sand. Practical implications of the findings from this study are discussed in detail.

• Journal of the Korean Geosynthetics Society
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• v.18 no.2
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• pp.45-54
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• 2019

This paper describes the results of finite element analysis (FEA), in order to investigate a characteristics of pile pullout behavior according to the conditions of the relative density and fines content in original ground. In the FEA, a boundary elements and strength reduction factors ($R_{inter}$) on pile-soil interface were applied to simulate appropriately the shear behavior at the pile-soil interface, and then the reliability of numerical analysis method was verified by comparison of FEA results and previous experimental research(You et al., 2018). In addition, a the deformation characteristics at the pile-soil interface and determination method of $R_{inter}$ value was laid out. The results showed that the FEA, based on the analytical model applied in this study simulates appropriately the characteristics of the pile-soil interface by pullout model test of pile. In order to apply the suggested $R_{inter}$ value, it is necessary to consider the condition of the relative density and the fines content in ground.

• Safety and Health at Work
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• v.9 no.4
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• pp.388-397
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• 2018

Background: The study analyzes penalties imposed on organizations for breaching safety and health regulations. The research questions are as follows: what are the commonly breached safety and health regulations? How proportional are penalties imposed on organizations for breaching health and safety regulations in the United Kingdom? Methods: The study employed sequential explanatory mixed research strategies for better understanding of health and safety penalties imposed on organizations. Actual health and safety convictions and penalties data for 10 years (2006 to 2016) were obtained through the United Kingdom Health and Safety Executive (HSE) public register for convictions. Overall, 2,217 health and safety cases were analyzed amounting to total fines of £37,179,916, in addition to other wide-ranging penalties. For thorough understanding, eight interviews were conducted with industry practitioners, lawyers, and HSE officials as part of the study qualitative data. Results: Findings show that the Health and Safety at Work (HSW) Act accounted for 46% of all HSE prosecution cases in the last decade. This is nearly half of the total safety and health at work prosecutions. Moreover, there is widespread desire for organizations to comply with the HSW Act, but route fines are seen as burdensome and inimical to business growth. Conclusion: A key deduction from the study reveal significant disproportionality concerning penalties imposed on organizations for breaching safety and health regulations. On aggregate, small companies tend to pay more for health and safety offenses in a ratio of 1:2 compared to large companies. The study also reveals that the HSW Act accounted for nearly half of the total safety and health at work prosecutions in the last decade.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.33 no.2
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• pp.17-23
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• 2001

AKD sizing behavior of handsheets, which were prepared from the different pulps with various AKD fixing agents, was studied in this investigation. AKD sizing performance could be improved by removal of fines in the stock, minimizing damage of fiber, using a suitable fixing agent and heat treatment. Fillers with low surface energy, like calcium carbonate and talc, showed quite positive effect in AKD sizing. When PAM was added to the DIP stock as fixing agent, it showed lower sizing degree than polyamine did. But in case of NBKP system, PAM was more effective than polymine.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.33 no.1
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• pp.45-52
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• 2001

Recycling of wastepaper is very important for the environmental protection. However inferior strength and slower drainage characteristic that are brought by the hornification and the increase of fines respectively limited the increase of wastepaper recycling. The purpose of this study is to obtain some fundamental information that is helpful to develop the technologies which can improve the characteristics of recycled fibers. Softwood bleached kraft pulp was curlated with Hobart mixer at several different consistency. The curlation of fibers can cause the internal fibrillation and decreasing the crystallinity without serious damage of fiber surface. Curl index, kink index, freeness and WRV were increased, but crystallinity was decreased with the increase of curlation consistency.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.33 no.2
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• pp.1-7
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• 2001

Use of high yield pulp and recycled fiber as raw materials and water system closure result in higher fines content and buildup of organic and inorganic contaminants in white water. These are detrimental for the effectiveness of chemical additives including retention aids. Thus it is imperative to employ a retention systems that maintains its efficiency in closed papermaking system for reducing fresh water consumption. The performance of four different microparticle retention systems including cationic polyacrylamide (C-PAM)/bentonite, highly charged cationic starch (HCS)/silica, C-PAM/micropolymer, cationic guar gum (CGG)/silica was evaluated and compared at three different levels of papermaking system closure. Buildup of detrimental substances in a closed white water system increased cationic demand and finally reduced the performance of retention systems. Cationic starch and guar gums maintained their effectiveness in retention in closed white water systems contaminated with anionic trashes because of their structural rigidity and hydrogen bonding ability. Particularly, cationic guar gums, due its stiffness of molecular structure, appeared perform better than catinonic starch.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.45 no.5
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• pp.23-29
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• 2013

Various properties of cotton handsheet were measured to solve the problem of deformation while storing guar gum(natural polymer) and to improve strength and retention by synthetic polymers(A-PAM, C-PAM, CMC). The results of this study were summarized as follow. The cotton handsheet with 0.2% of A-PAM showed the best tensile index and folding endurance. Retention of fines and fillers in pulp slurry with 0.2% and 0.3% of A-PAM were more excellent than that with guar gum.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.30 no.2
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• pp.30-39
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• 1998

Effect of cationic starches and anionic colloidal silica on retention and drainage characteristics of Compozil system was investigated. Depending upon the degree of substitution and molecular weight of cationic starches and morphological characteristics of anionic colloidal silica, retention and drainage properties of Compozil system were significantly influenced. When cationic starch addition level increased above a certain limit retention and stock freeness were decreased. To elucidate this an electrostatic coagulation mechanism occurring between unadsorbed starch molecules and anionic colloidal silica was proposed. Unstructured colloidal silica showed greater improvement in retention than structured colloidal silica. Cationic corn starches with different degree of substitution and molecular weights were prepared and their effect as a constituent of Compozil system was also evaluated. By controlling the molecular weight and degree of substitution of cationic corn starch it was possible to achieve significant improvement in fines retention. Cationic corn starch with higher degree of substitution maintained its retention efficiency even when the stock conductivity was increased. Turbidity measurement technique was found to be a simple and useful method to measure the retention characteristics.

• Advances in concrete construction
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• v.5 no.3
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• pp.183-199
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• 2017

This paper reports an experimental study into the rheological behaviour of Smart Dynamic Concrete (SDC). The investigation is aimed at quantifying the effect of the varying amount of mineral admixtures on the rheology, setting time and compressive strength of SDC containing natural sand and crushed sand. Ordinary Portland cement (OPC) in conjunction with the mineral admixtures was used in different replacement ratio keeping the mix paste volume (35%) and water binder ratio (0.4) constant at controlled laboratory atmospheric temperature ($33^{\circ}C$ to $35^{\circ}C$). The results show that the properties and amount of fine aggregate have a strong influence on the admixture demand for similar initial workability, i.e., flow. The large amounts of fines and lower value of fineness modulus (FM) of natural sand primarily increases the yield stress of the SDC. The mineral admixtures at various replacement ratios strongly contribute to the yield stress and plastic viscosity of SDC due to inter particle friction and cohesion.

• Journal of the Korean Wood Science and Technology
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• v.20 no.1
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• pp.51-59
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• 1992

The acetylation of papermaking pulp fiber(SwBKP, SwUKP, HwBKP and HwBCTMF) is carried out to modify the characteristics of pulp and paper. The effects of the addition of acetylated pulp on the filler retention and paper properties were investigated. The acetylation depended upon pulp type and the content of short fiber and fines. The addition of acetylated SwBKP did not deteriorate the retention of clay, talc and calcium carbonate, while the retention of titanium dioxide was increased with the addition of 20% and above. The brightness opacity, air permeability and tear strength were improved, but water resistance, burst strength and folding endurance were decreased by the addition of acetylated SwBKP and SwUKP. The tensile strength of SwBKP was increased until 20% of acetylated pulp is added, and then decreased. The tensile strength of SwUKP, however, was not changed until the acetylated pulp of 25% is added. The dimensional stability was improved by the addition of acetylated pulp and showed the different response to SwBKP and SwUKP.