• Journal of the Korean Society of Industry Convergence
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• v.11 no.3
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• pp.107-111
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• 2008

Usually, flow mediation earth and settling pond etc. of processing plant to handle water or wastewater. Mediation is the wastewater that flowed past settling pond than material of heavy particles, water weight colloid particles that big solids are removed but are suspensibility material settlement exclusion impossible. So, we need flocculation and coagulation action to remove materials from this colloid state. Flocculation and coagulation by addition of chemical agents forms floc settle size. That is, shorten the sedimentation time and quality of processing water because promoting sedimentation doing to do fines or suspended solids and colloid can materials large size and also, flocculation to annex efficiency of filtration augment. Therefore, I executed this research to prove that COD efficiency for wastewater by using inorganic coagulant.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.37 no.1 s.109
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• pp.1-9
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• 2005

Many factors which affect the adsorption of cationic polymers on fibers and fines have been investigated by many researchers that include contact time, pH, collision frequency, properties of cationic polymers and adsorbent, etc. But the effect of white water quality on the adsorption of cationic polymer have not been examined throughly. In this study, the adsorption of cationic PAM was analyzed as a function of white water quality. The adsorption of the cationic PAM was analyzed by two analysis methods, Kjeldahl nitrogen content measurement and electrokinetic measurements. When the distilled water was used, adsorbed amount of C-PAM and zeta-potential of fibers increased as a function of the addition of C-PAM. When closure level increased, nitrogen content of fibers increased indicating that the cationic PAM was adsorbed. Zeta-potential of fibers, however, showed no significant change with the increased addition of C-PAM. This showed that adsorption of C-PAM was not reflected by zeta-potential of fibers due to the deteriorated efficiency of C-PAM by the anionic contaminants in white water.

• KEPCO Journal on Electric Power and Energy
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• v.2 no.2
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• pp.279-284
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• 2016

Assessing the handling properties of coal becomes a major issue for the operation of a fuel supply system in power plants, due to the increased types of coal imported into Korea. In this study, the cohesion strengths of 13 bituminous and sub-bituminous coals from different countries were tested by measuring the amount of force that leads to a failure of consolidated particles. The particle size was in the range of 0.1-2.8 mm, which represents the coarse particles before pulverization. While the cohesion strength was proportional to the compression force in the tested range, the effects of the surface moisture content and the weight fraction of fines were crucial for cohesive coals. At fixed conditions of surface moisture and particle size, large variations were found in the cohesion propensity between coals. For coals of 0.1-0.5 mm with the moisture added close to the critical value, cohesive coals had the density over $900kg/m^3$ after consolidation. The cohesion propensity was not correlated with the basic properties of coals with sufficient statistical significance.

• Journal of the Korea Concrete Institute
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• v.11 no.4
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• pp.95-105
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• 1999

When superplasticizer is added to manufacture flowing concrete, the base concrete usually needs the adjustment to assure the sufficient fines contained to obtain flowable consistency without excessive bleeding or segregation. However, this may not only increase the cost, but also cause inconvenience in producing the base concrete. In this paper, the experiments are performed on normal base concrete to achieve a segregation-reducing flowing concrete by adding superplasticizer mixed with viscosity agents and AE admixtures. Three kinds of superplasticizer and two kinds of viscosity agent are selected. According to the results, with regard to the performance and cost of the admixtures, melamine type superplasticizer combined with the PEO viscosity agent and AE admixtures at the ratio 1:0.28:0.001 can acquire good quality and reduce the cost in producing the flowing concrete. With proper addition of combined superplasticizer, even though water to cement ratios of the base concrete are different, the segregation-reducing flowing concrete could be also achieved without reproportioning of the base concrete. However, it would be more desirable if the superplasticizer could be adjusted, before it is put into the practical use in order not to cause some other problems, such as rapid rate of slump loss and retarding of setting time.

• International Journal of Concrete Structures and Materials
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• v.3 no.1
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• pp.11-14
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• 2009

This paper is interested in the incorporation of crushed sand and desert sand in the composition the self compacting concretes (SCC). Desert dune sand, which has a fine extra granulometry, and the crushed sand, which contains an important content of fines, can constitute interesting components for SCC. Part II consists in studying the behaviour of SCC containing various sands with different origins. These sands, with different sizes, consist of several combinations of rolled sand (RS), crushed sand (CS) and desert sand (DS). The study examines the influence of the granular combination of sands on the characteristics in the fresh and the hardened state of SCC. The results of the experimental tests showed an improvement of the workability of the fresh SCC by combining sands of varied granulometry. The addition of the DS to CS or to RS allowed the increase of the mixture viscosity but decreased the mechanical strengths. Furthermore, the CS-RS combinations increased the compressive and the tensile strengths of the studied SCC. The optimized formulations of sands gave the highest performances of the SCC.

• Computers and Concrete
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• v.22 no.2
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• pp.183-196
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• 2018

The rheological behaviour of high strength self compacting concrete (HS-SCC) studied through an experimental investigation is presented in this paper. The effect of variation in supplementary cementitious materials (SCM) $vis-{\grave{a}}-vis$ four different types of processed crushed sand as fine aggregates is studied. Apart from the ordinary Portland cement (OPC), the SCMs such as fly ash (FA), ground granulated blast furnace slag (GGBS) ultrafine slag (UFS) and micro-silica (MS) are used in different percentages keeping the mix -paste volume and flow of concrete, constant. The combinations of rheology, strength and durability are equally important for selection of mixes in respect of high-rise building constructions. These combinations are referred to as the rheo-strength and rheo-durability which is scientifically linked to performance based rating. The findings show that the fineness of the sands and types of SCM affects the rheo-strength and rheo-durability performance of HS-SCC. The high amount of fines often seen in fine aggregates contributes to the higher yield stress. Further, the mixes with processed sand is found to offer better rheology as compared to that of mixes made using unwashed crushed sand, washed plaster sand, washed fine natural sand. The micro silica and ultra-fine slag conjunction with washed crushed sand can be a good solution for high rise construction in terms of rheo-strength and rheo-durability performance.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.37-38
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• 2007

It needs several large reservoirs and long time to remove suspended solid like steel fines and iron oxide in hot rolling coolant. If removing rate of suspended solid in rolling coolant is improved by using high gradient magnetic separation (HGMS) system, the productivity of working process can be increased and the area of reservoir can be reduced. Pre-treatment process that react magnetic floc with inorganic and organic flocculant in coolant was studied. Horizontal type superconducting HGMS system was manufactured successfully, which was constituted with automatic filter transportation apparatus, 6 T He-free superconducting magnet system and water circulation system. The solid suspension removal ratio in hot rolling coolant was increased by flocculation with inorganic and organic flocculant.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.42 no.5
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• pp.47-53
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• 2010

It is important to utilize the citrus sludge in terms of the reuse of waste materials in the manufacture of corrugated medium. Especially, the mandarin industry occupies the first place in Jeju province. In this paper, the application of citrus sludge mixed with KOCC recycled fibers into the manufacture of corrugated medium was studied. The citrus sludge was acidic in pH value. Also, the constituents of citrus sludge contain some short fibers, fines, and mucus which contain flavonoids, pectins and so on. In papermaking application, these components cause some troubles like foams, bad smell, fouling on the paper machine, and bad drainage and web breaks of wet web. The strength properties of handsheets prepared from KOCC and citrus sludge was decreased, compare to handsheets made of only KOCC. To compensate the problems on strength properties, some kinds of additives were tried to apply into papermaking wet-end system in laboratory scale. As a result, mixing conditions of alum, starch and anionic additives showed the best options in the recovery of strength properties and formations of corrugated medium.

• The Korean Society of Law and Medicine
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• v.13 no.1
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• pp.41-69
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• 2012

First introduced in 1977, Korean health care system reached to national coverage in short period of time never seen before in any other countries, and rated as successful system protecting the health of the public at relatively low price. However, despite those positive evaluations, some of fraudulent medical organizations or pharmacies are hindering the sound development of the national health care system with meticulous false billing exaggerating the number of patients or the days of their treatment. To prevent aforementioned nursing home fraud and false billing, the misconduct should be punished as subject to the criminal law and severally punished for fines and payments which far exceed the expected amount of illicit gains as it is basically violation of criminal fraud, other than the forced return of illicit gains based on civil laws. Furthermore, the Health Insurance Review and Assessment Service should strengthen and complement the fraud investigators, the review process, and the professional training to raise the detection rates. It might also want to review ways to implement whistleblower rewarding system and rewards for evidences of healthcare fraud to overcome the limits of external review.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.34 no.5
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• pp.63-69
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• 2002

A new concept of stock preparation for the increase of bending stiffness in paper and board was proposed. The "stiff" fibers, which were mechanically not treated or treated slightly to remove fiber curls, were combined with extensively refined fibers (ERF) to produce higher stiffness papers than those where the whole fibers were refined. The combination of "stiff" fibers and extensively refined fibers produced higher stiffness at the same tensile strength than the control furnish, in which all the fibers are refined together. In this concept, the fibers from recycled papers could be as much useful as the virgin fibers as long as they are stiff enough or they can produce highly bondable fiber fractions by extensive refining. Use of the concept in real paper mill needs considerations such as increase of refining energy, slower drainage, and added drying burden, but savings of wood fibers, utilization of more recycled fibers, and increase of physical properties may offset the negative concerns. The success of this concept implementation in mills, therefore, depends on the wood fiber market around the mills and the proper decision making for the papermakers about how to apply this concept. apply this concept.