• Proceedings of the Korea Concrete Institute Conference
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• 2005.05b
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• pp.149-152
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• 2005

To make artificial light-weight aggregate with EAF-dust and estimate ability to apply to concrete, characteristics of the aggregate were considered in density, weight of unit volume, fineness modulus and so on. And then it was executed to experiments of the concrete mixed with the light-weight aggregate. As it was results that artificial light-weight aggregate with EAF-dust was heavier and more watertight than with only clay, concrete weight of unit volume was heavier than with expended clay aggregate. But it was regarded that concrete with EAF-dust artificial aggregate was able to field application as light-weight concrete because concrete of the weight of unit volume was lighter and compress strength and workability were similar to normal concrete.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.03a
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• pp.1167-1174
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• 2005

This paper describes on the volume change of Sewage Dredged Soils by using laboratory test and volumetric change test. The tremendous change of Moisture Content occured in the Sewage Dredged Soils during the Elapsed Time. The Unit Weight increases during the normally shrinkage limit void ratio and then the unit weight decrease. A volume of Sewage Dredged Soils according to the moisture content is a difference maximum 2.5 times. And there is the difference 3.5 times according to the change of unit weight. Therefore, the moisture content and unit weight computation are very important for the computation on the volume of Sewage Drdeged Soils.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2013.05a
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• pp.35-36
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• 2013

Electric arc furnace oxidizing slag from massively produced steel slag has been used in road bases and subbases, hot mix asphalt, and landfill. Electric arc furnace oxidizing slag contains iron (15%~30%) and has a high density of 3.0~3.7 ton/m3. Depending on the type and amount of concrete aggregates, the radiation-shielding characteristics can vary. Therefore, aggregates of electric arc furnace oxidizing slag can be considered for the production of radiation-shielding concrete. The experimental design of this study is experiments on Compressive strength experiments, X-ray irradiation experiments, and experiments related to the unit volume weight were carried out on hardened concrete. This experiment compared the performance evaluation of radiation shielding of concrete using electric arc furnace oxidizing slag.

• Computers and Concrete
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• v.33 no.4
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• pp.471-479
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• 2024

In urban areas, appropriate backfilling design is necessary to prevent surface subsidence and subsurface cavities after excavation. Expandable foam grout (EFG), a mixture of cement, water, and an admixture, can be used for cavity filling because of its high flowability and volume expansion. EFG volume expansion induces a porous structure that can be quantified by the entrapped air content. This study observed the unit weight variations in the EFG before and after expansion depending on the various admixture-cement and water-cement ratios. Subsequently, the air content before and after expansion and the gravimetric expansion ratios were estimated from the measured unit weights. The air content before expansion linearly increased with an increase in the admixture-cement ratio, resulting in a decrease in the unit weight. The air content after the expansion and the expansion ratio increased nonlinearly, and the curves stabilized at a relatively high admixture-cement ratio. In particular, a reduced water-cement ratio limits the air content generation and expansion ratio, primarily because of the short setting time, even at a high admixture-cement ratio. Based on the results, the relationship between the maximum expansion ratio of EFG and the mixture ingredients (water-cement and admixture-cement ratios) was introduced.

• Journal of Korean Elementary Science Education
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• v.21 no.2
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• pp.201-212
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• 2002

This paper aims to find out how did elementary students understand scientific units in science textbooks. The subjects were 191 students of the 6th grade from 7 elementary schools in 3 different areas, consisting of 70 from 4 village schools of, 64 from 2 town schools of Gyeongnam province, and 57 from one city school in Ulsan Metro City. A test was developed based on the analysis of scientific units in the science textbooks and teacher's manuals constructed according to the 6th and 7th National Science Curriculum. The understanding of elementary students' on the scientific units(Temperature, Length, Weight, Volume, Speed, Plane Angle) were surveyed. The result are as follows: Regarding the temperature unit, the students generally well understand why to measure and how to read temperature, but had some problem in recording it, in confusion with the plane angle sign. As for the length unit, they obtained high scores in understanding the purpose of measuring length as well as recording and reading it. Which indicates that they are well aware of and use the unit appropriately. With respect to the weight unit, they got high scores in reading and recording weight, which means most students have no problem using the unit. However, it was found that they do not understand why to use the plate balance scale. The volume unit was one in which the students got relatively lower scores. They do not perceive the object of using a scale cylinder and confuse it with a device of length measurement. The unit of speed is the most difficult one for children's of science to understand, presumably, because it is an derived unit from two basic units. It is also assumed that the students got the highest score in the plane angle unit because they studied the unit immediately before the test. From the children's understanding of science units above the teacher's understanding and teaching methods presumed to play a major role for children to understand and use the science units properly.

• International Journal of Railway
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• v.8 no.1
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• pp.10-14
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• 2015

Due to the characteristics of the vehicle structure, the magnetic levitation train has a confined bottom space thus a study on miniaturization and weight reduction of auxiliary power unit is essential. This auxiliary power unit is an essential device used for illumination, air conditioning, heating and air brake equipment excluding the motor. The previous auxiliary power unit for magnetic levitation train has used the hard switching having a high switching frequency with heavy loss in order to reduce the size of filter reactor and transformer but the reduction in volume was not significant. In this paper, by reducing the loss, reducing the size of the cooling unit and by increasing the switching frequency using the soft switching of resonant converter, it has miniaturized and reduced the weight of filter reactor and transformer which occupy significant space in the auxiliary power unit. This study has verified the performance of 50KVA grade prototype through simulated interpretation and analysis, and compared the size and weight of auxiliary power unit of the previous magnetic levitation train.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• v.18 no.2
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• pp.100-107
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• 2015

Purpose: We investigated the iron status of very low birth weight infants receiving multiple erythrocyte transfusions during hospitalization in the neonatal intensive care unit (NICU). Methods: We enrolled 46 very low birth weight infants who were admitted to the Kyungpook National University Hospital between January 2012 and December 2013. Serum ferritin was measured on their first day of life and weekly thereafter. We collected individual data of the frequency and volume of erythrocyte transfusion and the amount of iron intake. Results: A total of 38 (82.6%) of very low birth weight infants received a mean volume of $99.3{\pm}93.5mL$ of erythrocyte transfusions in NICU. The minimum and maximum serum ferritin levels during hospitalization were $146.2{\pm}114.9ng/mL$ and $456.7{\pm}361.9ng/mL$, respectively. The total volume of erythrocyte transfusion was not correlated to maximum serum ferritin concentrations after controlling for the amount of iron intake (r=0.012, p=0.945). Non-transfused infants took significantly higher iron intake compared to infants receiving ${\geq}100mL/kg$ erythrocyte transfusion (p<0.001). Minimum and maximum serum ferritin levels of non-transfused infants were higher than those of infants receiving <100 mL/kg erythrocyte transfusions (p=0.026 and p=0.022, respectively). Infants with morbidity including bronchopulmonary dysplasia or retinopathy of prematurity received a significantly higher volume of erythrocyte transfusions compared to infants without morbidity (p<0.001). Conclusion: Very low birth weight infants undergoing multiply erythrocyte transfusions had excessive iron stores and non-transfused infants also might had a risk of iron overload during hospitalization in the NICU.

• Journal of the Korean Geotechnical Society
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• v.32 no.2
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• pp.53-62
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• 2016

Among several factors controlling soil compaction, temperature is the factor that varies with region and season. Although earthwork is performed in many projects in the cold regions of the earth, studies on quantifying soil compaction associated with temperature are limited. This experimental study investigates the temperature effect on the soil compaction of cohesionless soil. Jumunjin sand was selected for the tests to represent cohesionless clean sand, which is widely used as an engineering fill at petrochemical projects such as northern Alberta of Canada and Russia. The laboratory test program consists of performing a series of standard proctor tests varying temperature of soil samples ranging from $-10^{\circ}C$ to $17^{\circ}C$. Test results indicate that soil specimen volume expansion occurred from bulking and its range was 0% to 6% with zero above temperature. For increasing temperature from $0^{\circ}C$ to $17^{\circ}C$, water content corresponding to maximum volume (minimum dry unit weight) was decreased and water content corresponding to minimum volume (maximum dry unit weight observed after reaching minimum dry unit weight) was slightly increased with increasing temperature. In zero below temperature, dry unit weight gradually decreased with increasing water content. In this case, no bulking effect was found and soil specimen volume increased due to the higher unit volume of ice.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2003.10a
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• pp.169-174
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• 2003

Design of a rational earth volume conversion coefficient is required as the earth volume conversion coefficient may give great influence on construction work volume and construction costs in the civil engineering works where large-scaled earth volume is excavated. However, there are a great deal of difficulties in the calculation of the exact spoil surface earth and Insufficient earth volume by adopting the figures presented on the generally used design specifications which are not the results obtained from the selection tests in calculating the earth volume conversion coefficient. In this connection, it would be desirable to calculate the earth volume conversion coefficient by carrying out large-scaled site test adequate for the relevant environment. In consequence, this study aims at calculating the exact earth volume conversion coefficient of cutting and banking areas of weathering rocks in large-scaled construction sites where land is being developed into home lots. For this, we have excavated the respective 20 sites of the cutting and banking areas in the said site and then calculated the volume after the excavation. As a result, the relative exactness degree of the crossing was calculated at 0.5% in average. The relative exactness degree of 0.5% in the volume may be judged as an exact measurement as it corresponds to 0.17% of the relative exactness degree in the length measurement. We have calculated the exact earth volume conversion coefficient by the use of function ratio as per the wet unit weight and the indoor soil quality test as per volume calculated. And then we have found out minor differences as a result of the comparison and analysis with the earth volume conversion coefficient determined by the dry unit weight test as per sand replacement method. This may be judged as a rational design method for the calculation of earth volume conversion coefficient, as well as high reliability of site test as a precision photogrammetry is adopted for volume measurement of the irregular excavating areas.

• KCI Concrete Journal
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• v.11 no.3
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• pp.19-28
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• 1999

This study treated self-compacting high Performance concrete as two Phase materials of Paste and aggregates and examined the effect of powder and aggregates on self-compacting high performance, since fluidity and segregation resistance of fresh concrete are changed mainly by paste. To improve the fluidity and self-compactibility of concrete, optimum powder ratio of self-compacting high performance concrete using fly ash and blast-furnace slag as powders were calculated. This study was also designed to provide basic materials for suitable design of mix proportion by evaluating fluidity and compactibility by various volume ratios of fine aggregates, paste, and aggregates. As a result, the more fly ash was replaced, the more confined water ratio was reduced because of higher fluidity. The smallest confined water ratio was determined when 15% blast-furnace slag was replaced. The lowest confined water ratio was acquired when 20% fly ash and 15% blast-furnace slag were replaced together. The optimum fine aggregates ratio with the best compactibility was the fine aggregate ratio with the lowest percentage of void in mixing coarse aggregate and fine aggregate In mixing the high performance concrete. Self-compacting high performance concrete with desirable compactibility required more than minimum of unit volume weight. If the unit volume weight used was less than the minimum, concrete had seriously reduced compactibility.