• Proceedings of the Korean Institute of Building Construction Conference
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• 2023.11a
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• pp.77-78
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• 2023

This paper experimentally examined the recycling of combustion by-products emitted from a combined heat and power plant using lignocellulosic biomass fuel. Physical and chemical analyzes were performed on Bio-SRF and three types of wood pellet combustion by-product samples (fly-ash, FA). As a result of the experiment, the compressive strength of mortar substituted with 5, 10, and 20% of FA compared to the cement weight was found to be excellent, and its recyclability was confirmed as a substitute for existing admixtures.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.29 no.3
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• pp.7-16
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• 1997

The constituents of deposits on paper machine and holes/spots in paper have been studied by consequently a combination of analytical techniques, such as FTIR, Py-GC-MS, and. EDS. FTIR spectroscopy was used prior to Py-GC-MS and EDS analysis, as preliminary analysis technique. The analysis of organic components were carried out with the use of a pyrolysis unit connected to a GC-MS, and inorganic components in ash were analysed by SEM equipped with an EDS analyzer after pyrolysis at 59$0^{\circ}C$. The deposits on the dryer section were complex pitch, which was the mixture of the organic contents of fatty acid ester and starch, and the inorganic contents of talc, clay, and calcium carbonate. The complex pitch was estimated to come from the coated broke. We knew the deposits on the metering rod of sym-sizer were associated with the interaction of unstable AKD and CaCO$_3$. The compositions of holes or spots varied considerably and were associated with chemical interaction within the system. The holes, spots, and blotches in the finished paper were PE and PP that were streamed out from pulp sources, complex pitch that were caused by the interaction of the different additives in the system, polymer such as flexible PVC that used for the prop of palette, and hot melt as adhesives that came from the inadequate handling of broke. In addition, we identified that poly(caprolactam) which is used for forming fabrics or press felts, could be mixed with the raw materials by accident and results in streak on coating.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 2000.04a
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• pp.55-55
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• 2000

Cylinder machine usually gives more fiber orientation than fourdrinier and has limitation in machine speed because of fiber wash-off caused by centrifugal force in case of adding machine speed. This study aimed at improvement of paper formation and higher productivity by setting up an apron in vat inlet and by adjustment of mould water head. As results, there were improvement of formation and increase of machine speed, which ultimately improve productivity. Setting up an apron successfully decreased fiber wash-off. Fiber orientation and two-sideness of ash distribution became less severe. These results could lead to better dimension stabilities in the CD through mitigation of fiber orientation and also could result in less curl from two-sideness of paper. The proper adjustment of water head inside the cylinder mould proved to be important factor not only in paper formation but also in decreasing paper two-sideness.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.45 no.6
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• pp.24-29
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• 2013

In this study, we investigated the applicability of PCC(precipitated calcium carbonate) as a raw material for the manufacture of duplex-board. Papers were made with white-ledger stock collected from the actual duplex-board mill and PCC in a laboratory, and paper properties including bulk, ash content, tensile strength, burst strength, brightness and opacity were measured. The effect of PCC on the drying energy of duplex-board was also determined by measuring the moisture content of wet web and calculating drying energy reduction. PCC increased bulk and ISO brightness significantly, which means PCC can decrease the use of virgin pulp and recycled fibers. PCC decreased the moisture content of wet web, which means PCC can decrease drying energy consumption. However, paper strength decreased as addition levels of PCC addition increased. Therefore, the addition level of PCC must be determined considering the reduction of paper strengths.

• Journal of the Korean Society of Safety
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• v.28 no.6
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• pp.11-16
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• 2013

This paper presents a study on the analyzing reliability of smoke fire detector using accelerated life test. In general, the smoke fire detector is broken by dust which flow in smoke detection chamber. In order to conduct accelerated life test of smoke fire detector dust is set accelerated factor in this paper. The dust is fly-ash which is test particle 5th regulated by KS A 0090. The dust accelerated level is 60 g, 180 g and 360 g and failure time is measured by smoke sensitivity testing. It is considered to failure of detector if detector don't operate within 30 secconds when subjected to an air stream having a velocity of 20 cm/s~40 cm/s containing smoke with a concentration of 15% of rate of light-response of 1 m. The goodness of fit test and mean life prediction conduct using the failure time. The result show that life distribution fits the weibull distribution for failure time data and the mean lifes calculate 22.5 year in domestic product and 14.7 years in overseas product applied dust stress only.

• Computers and Concrete
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• v.19 no.6
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• pp.651-658
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• 2017

High-performance concrete, besides aggregate, cement, and water, incorporates supplementary cementitious materials, such as fly ash and blast furnace slag, and chemical admixture, such as superplasticizer. Hence, it is a highly complex material and modeling its behavior represents a difficult task. This paper presents an evolutionary system for the prediction of high performance concrete strength. The proposed framework blends a recently developed version of genetic programming with a local search method. The resulting system enables us to build a model that produces an accurate estimation of the considered parameter. Experimental results show the suitability of the proposed system for the prediction of concrete strength. The proposed method produces a lower error with respect to the state-of-the art technique. The paper provides two contributions: from the point of view of the high performance concrete strength prediction, a system able to outperform existing state-of-the-art techniques is defined; from the machine learning perspective, this case study shows that including a local searcher in the geometric semantic genetic programming system can speed up the convergence of the search process.

• Journal of the Korean Wood Science and Technology
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• v.48 no.2
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• pp.231-244
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• 2020

As a way of finding value-added materials from waste medium density fiberboard (MDF), this study characterized cellulose nanocrystals (CNCs) isolated by ammonium persulfate (APS) oxidation using recycled MDF fibers. Chemical composition of the recycled MDF fibers was done to quantify α-cellulose, hemicellulose, lignin, nitrogen, ash and extractives. The APS oxidation was performed at 60 ℃ for 16 h, followed by ultrasonication, which resulted in a CNC yield of 11%. Transmission electron microscope images showed that rod-like CNCs had an average length and diameter of 167±47 nm and 8.24±2.28 nm, respectively, which gave an aspect ratio of about 20. The conductometric titration of aqueous CNCs suspension resulted in a carboxyl content of 0.24 mmol/g and the degree of oxidation was 0.04. Attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy clearly showed the presence of carboxyl group on the CNCs prepared by the APS oxidation. The change of pH of the aqueous CNC suspension from 4 to 7 converted the carboxyl group to sodium carboxylate group. These results showed that the APS oxidation was facile and CNCs had a one-step preparation method, and thus suggested an optimization of the oxidation condition in future.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.44 no.5
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• pp.1-7
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• 2012

Chemical composition, morphological properties and papermaking properties of Sasa quelpaertensis Nakai were investigated in order to use it comprehensively. The lignin contents of stalks and leaves were 18.8% and 15.3% and the holocellulose contents were 63.3% and 48.6% respectively. The contents of ash and the amount of water extract showed the higher value than those of wood or other bamboo species. The average fibers length and width of Sasa quelpaertensis Nakai were 780 ${\mu}m$ and 14.8 ${\mu}m$. The fibers of Sasa quelpaertensis Nakai stalk had thinner width and more slender structure than those of softwood. The handsheet made of Sasa quelpaertensis Nakai alkaline pulp showed higher in tensile strength and bulkier structure than those of handsheet made of soft wood unbleached kraft pulp.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 2011.04a
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• pp.139-150
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• 2011

The effects of the high pressure and the high temperature digesting process with water on the properties of rice hull were investigated in this work. Two temperature condition such as $160^{\circ}C$ and $180^{\circ}C$ and thee treatment time such as 15 min, 30 min and 45 min were applied for this treatment. The pH of extract after the digestion process decreased as the temperature and the treatment time of the digestion were increased. The ash content and lignin content were not decreased by the the digestion. The structure of rice hull after digestion treatment became more weak, the better efficiency of the fiberization with PFI-Mill was shown for the digestion treated rice hull with the higher temperature and the longer treatment time.

• Transactions of the Korean hydrogen and new energy society
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• v.20 no.4
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• pp.352-359
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• 2009

KEPRI is developing a Korean type coal-gasification system and the scale is 20 ton/day. Prior to this pilot plant, a 1 ton/day class gasification system will be used for pre-testing of several coal types. This paper introduces the configuration and design conditions of this 1 ton/day class system, presenting the gas/coal ratio, oxygen/coal ratio, cold gas efficiency, CFD analysis of gasifier, and others. The existing combustion furnace for residual oil was retrofitted as a coal gasifier and a vertical and down-flow type burner was manufactured. Ash removal is carried out through a water quencher and a scrubber following the quencher, and the sulfur is removed by adsorption in the activated carbon tower. The gas produced from the gasifier is burned at the flare stack. In this paper, the results of design conditions and initial operation conditions of I ton/day gasification system are compared together.