• The Journal of Engineering Geology
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• v.13 no.3
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• pp.345-358
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• 2003

Recently, the reuse of coarse aggregate derived from demolished concrete was introduced into practice with two environmental aspects: protection of natural sources of aggregate and recycling of construction waste. However, recycled aggregate has been used for the very limited application such as subbase material for pavement and constructional filling material because it was considered as low quality constructional materials. In the present study, in order to examine the possibility that recycled aggregate can be used for concrete mixing, we conducted various experimental tests to identify mineralogical, chemical and mechanical properties of recycled aggregate and to determine the workability and mechanical properties of recycled aggregate concrete (RAC). The cement paste and mortar contained in recycled aggregate significantly affect the basic mechanical properties of aggregate and the workability and mechanical properties of RAC. However, RCA mixed with the proper replacement ratio of recycled aggregate shows the comparable compressive strength and freeze and thaw resistance to those of normal concrete. Therefore, it is considered that recycled aggregate can be widely used for concrete if the cement paste and mortar can be efficiently removed from recycled aggregate and/or if the effective replacement ratios of recycled aggregate are applied for mixing concrete.

• Journal of Preventive Medicine and Public Health
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• v.48 no.6
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• pp.330-341
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• 2015

Objectives: Emergency medical personnel (EMPs) are pre-hospital emergency responders who are at risk of exposure to infections and may also serve as a source for the transmission of infections. However, few studies of infection control have specifically addressed EMPs in the Republic of Korea (hereafter Korea). The goal of this study was to assess the current status of infection prevention and control programs (IPCPs) for EMPs in Korea. Methods: A cross-sectional survey was conducted to quantitatively assess the resources and activities of IPCPs. A total of 907 EMPs in five metropolitan cities completed a structured questionnaire from September 2014 to January 2015. The data were analyzed using descriptive statistics, multi-response analysis, and the chi-square test. Results: The mean age of the participants was $34.8{\pm}15.1years$. IPCPs were found to have weaknesses with regard to the following resources: the assignment of infection control personnel (ICP) (79.5%), hand hygiene resources such as waterless antiseptics (79.3%), the use of paper towels (38.9%), personal protective equipment such as face shields (46.9%), and safety containers for sharps and a separated space for the disposal of infectious waste (10.1%). Likewise, the following activities were found to be inadequately incorporated into the workflow of EMPs: education about infection control (77.5%), post-exposure management (35.9%), and the decontamination of items and spaces after use (88.4%). ICP were found to have a significant effect on the resources and activities of IPCPs (p<0.001). The resources and activities of IPCPs were found to be significantly different among the five cities (p<0.001). Conclusions: IPCPs for EMPs showed some limitations in their resources and activities. IPCPs should be actively supported, and specific IPCP activities for EMPs should be developed.

• Applied Biological Chemistry
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• v.29 no.1
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• pp.44-50
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• 1986

Two fractions of ${\beta}-glucanase$(CMCase), two fractions of filter paper degradation enzyme (FPase) and one ${\beta}-glucanase$ fraction were partially purified from Fusarium moniliforme and applied to recovery process of red bean starch. Red bean were incubated with the fractions of CMCase and FPase at $50^{\circ}C$ for 2 hours and the starch granules are separated. Maximal sedimentation rate of red bean starch granules was obtained with treatment of the mixture solution of 0.004 units/ml of FPase and 0.3 units/ml of CMCase. In the enzyme treated process percent recovery of red bean starch granule increased about 7% and suspended solid in waste water was reduced about 40%, compared with those of control. The results indicated that red bean cell treated with cellulase fractions absorbed water more rapidly and specific gravity of starch granule increased.

• The KSFM Journal of Fluid Machinery
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• v.19 no.4
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• pp.48-53
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• 2016

The centrifugal separator which uses gravity separation method for oil-water separation, rotating at high-speed, is one of the most commonly used device for controlling the amount of the oil in waste water collected in bilge. The IMO (International Maritime Organization) has set regulations, also known as MARPOL 73/78, for the prevention of marine pollution. In addition, DET NORSKE VERITAS (DNV) has set standards regarding the assignment of Environmental Class Notation, CLEAN or CLEAN DESIGN, of ships. One of the requirements for classification is that in addition to conforming to MARPOL 73/78, more stringent measures must be taken as well. One of these measures is to limit the oil concentration in bilge water to less than 5ppm. So in this study, an Oil-Water Separator (OWS) is used together with multiple separating plates as a filtration system to be used as an oil-water separation device. The OWS operates using centrifugal separation in which the mixture is separated by centrifugal forces. The main purpose of this paper is to present the OWS separation efficiency according to the rotation speed, mass-flow rate, the angle and the number of stacked layers of the laminated plate using Computational Fluid Dynamics (CFD). Improvements to the device will be investigated from these results.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.2
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• pp.75-81
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• 2005

The GNUnet in P2P system have solved an anonymous(publisher, storer, demander); a service of condition equal for peer. The GNUnet for an anonymous has separated a file and dispersed to the network. But, the 1Kbyte block size of the GNUnet is a creation of many additional block. I and R block has created with indirect point of D block The waste of I and R block appeared to 4% of the original file and the additional network traffic for the block transmission. To resolve the problems, this paper proposes an new scheme of file splitting distribution using P2P networks with the new GNUnet protocol, The GNUnet support minimization of the additional block and for a network traffic. It proposed an efficiency improvement of encording block and routing algorithm.

• Analytical Science and Technology
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• v.13 no.1
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• pp.81-88
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• 2000

A rapid preconcentration method was developed for the speciation of the trace mercury compounds in water sample. The mercury compounds were extracted and preconcentrated simply as their dithizone complexes by passing through the dithizone impregnated ultra-high molecular weight polyethylene (UHMWPE) membrane solvent inlet filter following sanification in methanol solvent. The concentrated dithizonates were separated by liquid chromatography on a $C_{18}$ column. Complete resolution was obtained between methyl-, ethyl-, phenyl-, and inorganic mercury with a mobile phase of 0.05 M acetate buffer (pH=4)/THF/methanol(3:5:2). The separnted mercury chelates were detected by spectrophotometrically at 475 nm. The proposed method was successfully applied to the speciation of mercury compounds in waste water with detection limit at the subnanogram/mL level.

• Korean Journal of Agricultural Science
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• v.45 no.4
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• pp.789-797
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• 2018

This study investigated the activity of crude enzymes obtained from Pyrus pyrifolia cv. Shingo on milk proteins. In the milk processing industry, there is an increasing interest in the addition of functional materials to dairy products or functional peptides isolated from milk proteins. First, Pyrus pyrifolia cv. Shingo was separated into core, flesh, and peel regions, and crude enzymes were obtained from the individual regions. The activity of the obtained crude enzymes was measured using casein and gelatin agar. The crude enzyme obtained from the flesh of Pyrus pyrifolia cv. Shingo decomposed gelatin, but the activity of the crude enzymes obtained from the peel and core regions was insignificant. On the other hand, the crude enzymes obtained from the flesh and core regions of Pyrus pyrifolia cv. Shingo had a remarkable enzymatic activity in casein agar. However, the activity of the crude enzyme obtained from the peel region was insignificant. In addition, the crude enzymes obtained from the individual regions were mixed with casein to induce reactions, and the degradation patterns were investigated through electrophoresis and high performance liquid chromatography (HPLC). According to the results, the crude enzymes from Pyrus pyrifolia cv. Shingo degraded milk proteins. Thus, the results of this study can be used in studies on functionality. Additionally, it is expected that the use of pear peels and cores in the milk processing industry would greatly contribute to the reduction of food waste.

• Journal of Urban Science
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• v.10 no.1
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• pp.29-37
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• 2021

The number of old buildings older than 30 years in Korea continues to increase from 29.9% in 2005 to 38.8% in 2020. Considering the growing urban regeneration projects, urban maintenance projects, the suppression of urban expansion, and the lack of idle land in the city, the dismantling of old buildings is expected to increase further in the future. As major accidents at building dismantling sites continue to occur, related agencies are also strengthening safety management of building dismantling works. While physical safety management such as collapse and fall is strengthened, there is a relative lack of interest in the health of workers at dismantling sites due to environmental hazards. Since relevant laws stipulate that construction waste should be separated and discharged, old buildings need to be considered for environmental hazards such as fine dust, floating bacteria, and floating molds when dismantling. In this study, we intend to find important safety management elements in the management of building dismantling sites, measure environmental factors harmful to dismantling workers, and present basic data for the management of dismantling sites in the future. "Safety management" was the highest priority, followed by "dust," "vibration," "noise," "bacteria," and "smell." The perception of the importance of "physical damage prevention" with workers working on dismantling and managers managing the site came out similar, but the perception of "work efficiency" and "health disorder prevention" through environmental hazard management showed different priorities. In the process of dismantling, floating bacteria and floating mold were collected, cultured, and measured the concentration in the indoor air. The measurement was measured by dividing it into pre-dismantling and during dismantling.

• Journal of the Korean Wood Science and Technology
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• v.51 no.5
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• pp.334-344
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• 2023

Dregs from the sugar palm (Arenga pinnata) starch industry are considered a waste product of the agricultural industry and have not yet been optimally utilized. Therefore, this study aimed to manufacture particleboards from dregs using different amounts of adhesive and particle size ratios. Sugar palm dregs, which had been separated into fibers and powder/fine particles, were used as raw material for making particleboards. The fiber had an average length of 6.84 ± 3.23 cm, while the fine particles were of a size that passed through size 10 mesh and remained in size 60 mesh. Three ratios of fiber to fine particles (100:0, 75:25, and 50:50 wt%) with three different amounts of sucrose-citric acid adhesive (10, 15, and 20 wt%) were used in this study. Increasing the amount of fine particles and the resin content can improve the physical properties and the internal bond strength of boards made from sugar palm dregs. The fine particles possibly filled the gap between the fibers in the particleboard, while the fibers exhibited a high bending strength. As a result, a high-performance particleboard can be attained by combining the composition ratio of fiber/fine particles and resin content. In this study, particleboards made from fiber/fine particles (75:25 wt%) and adhesive content of 15 wt% and 20 wt% had the mechanical properties that met the requirements of Japanese Industrial Standard (JIS) A 5908 type 18. Sugar palm dregs have the potential to be used as raw materials to create value-added particleboards.

• Resources Recycling
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• v.28 no.6
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• pp.96-105
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• 2019

Automobile shredder residue (ASR) is the final waste produced when end-of-life vehicles (ELVs) are shredded. ASR can be separated using mineral-processing operations such as comminution, air classification, magnetic separation, and/or electrostatic separation. In this work, trajectory analyses of conductors (copper) and non-conductors (glass) in the ASR have been carried out using induction electrostatic separator for predicting or improving the ASR-separation efficiency. From results of trajectory analysis for conductors, the trajectories of copper wire by observation versus simulation for coarse particles of 0.5 and 0.25 mm showed consistent congruity. The observed 0.06 mm fine-particles trajectory was deflected toward the (-) attractive electrode owing to the charge-density effects due to the particle characteristics and relative humidity. In the case of non-conductors, the actual trajectory of dielectric glass deflected toward the (-) electrode, showing characteristics similar to those of conductive particles. The analyses of stereoscopic microscope and SEM & EDS found heterologous materials (fine ferrous particles and conductive organics) on the glass surface. This demonstrates the glass decreasing separation efficiency for non-ferrous metals during electrostatic separation for the recycling of ASR. Future work will require a pretreatment process for eliminating impurities from the glass and advanced trajectory-simulation processes.