• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.1259-1260
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• 2006

Intensive technological research on the Dry-bag CIP equipment was carried out to improve the dimensional accuracy and the productivity. The rubber mold design technology using FEM simulation during pressing was introduced, in order to achieve higher dimensional preciseness, and criteria for the selection of the In-line type or Off-line type, were established based on the powder flowability index proposed by Carr. Based on these research results, high productivity Off-line Dry-bag CIP equipment, which can realize good dimensional accuracy with high productivity, was developed even for non-granulated powders with poor packing density.

• International Journal of Highway Engineering
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• v.17 no.1
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• pp.51-58
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• 2015

PURPOSES : The objective of this study is to compare the densities of asphalt pavements measured both in the field and in the laboratory, and also to evaluate the applicability of field density measuring equipment, such as the pavement quality indicator (PQI), by using statistical analysis. METHODS : For the statistical analysis of the density measured from asphalt pavement, student t-tests and a coefficient of correlation are investigated. In order to compare the measured densities, two test sections are prepared, with a base layer and an intermediate layer constructed. Each test section consists of 9 smaller sections. During construction, the field densities are measured for both layers (base and intermediate) in each section. Core samples are extracted from similar regions in each section, and moved to the laboratory for density measurements. All the measured densities from both the field and laboratory observations are analyzed using the selected statistical analysis methods. RESULTS AND CONCLUSION : Based on an analysis of measured densities, analysis using a correlation coefficient is found to be more accurate than analysis using a student t-test. The correlation coefficient (R) between the field density and the core density is found to be very low with a confidence interval less than 0.5. This may be the result of inappropriate calibration of the measuring equipment. Additionally, the correlation coefficient for the base layer is higher than for the intermediate layer. Finally, we observe that prior to using the density measuring equipment in the field, a calibration process should be performed to ensure the reliability of measured field densities.

• Transactions on Electrical and Electronic Materials
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• v.12 no.3
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• pp.98-101
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• 2011

A 10 nm nano-silica was introduced to a conventional 3 ${\mu}M$ micro-silica composite to develop an eco-friendly new electric insulation material for heavy electric equipment. Thermal and mechanical properties, such as glass transition temperature (Tg), dynamic mechanical analysis, tensile and flexural strength, were studied. The mechanical results were estimated by comparing scale and shape parameters in Weibull statistical analysis. The thermal and mechanical properties of conventional epoxy/micro-silica composite were improved by the addition of nano-silica. This was due to the increment of the compaction via the even dispersion of the nano-silica among the micro-silica particles.

• Proceedings of the KSR Conference
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• 2008.06a
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• pp.158-167
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• 2008

The quality control of compacted fills has been carried out by evaluating relative densities and coefficients of soil reaction. These measures have several limitations regarding repeatability and reliability of field measurements, and difficulties to use in the fills including large grain size as gravels and boulders. Also, the density is not directly related to the design parameter such as resilient modulus. A preliminary investigation for the usage of the stiffness as a control measure has been carried out. In the laboratory, the stiffness (P-wave velocity) was measured during compaction tests. The stiffness at the optimal moisture content was proposed to use a target control parameter likewise maximum dry density. A field method to match the target stiffness was also proposed by considering easiness of the method and availability of equipment. The most phenomenal feature of the method is that the control parameter (stiffness) is closely related to resilient modulus and can be consistently used from the design stage to the field control during construction.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.2
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• pp.175-181
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• 2020

This paper suggests a proper hydraulic filling method in downtown areas. Road subsidence on roadways and sidewalks in downtown areas can result in vehicle damage and casualties. The representative cause of road subsidence is the fraudulent construction in nearby construction sites. A deficiency of excavation restoration causes approximately 25~49% of subsidence. This is performed by equipment or manpower. Hydraulic filling is used in backfilling narrow pipe conduits and spaces between structures. On the other hand, standard specifications and quality assurance standards regarding hydraulic filling principles and construction conditions are insufficient. Therefore, in-door model experiments on hydraulic filling principles, backfilling material, and compaction efficiency were performed. This paper suggests guidelines by investigating and analyzing construction status. In conclusion, thrown backfilling material has a particle size distribution and permeability coefficient as major factors, and detailed standards of the factors are suggested. To improve the compaction efficiency, 90% or more, compaction by the floor should be in units of 0.3m while ensuring a lower drainage layer. When an H-shape stabilizing pile is pulled out after filling, additional hydraulic filling should be in the disturbance range.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.40 no.5
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• pp.421-428
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• 2022

The earthwork is a core process of all constructions, and compaction measurement of earthwork play an important role in improving productivity. The analog tests such as Plate Bearing Test and Sand-cone occupy current compaction measurement techniques. Due to advanced 4th Industrial Revolution, research on analog tests combined smart construction technology are actively conducted. DCPT (Dynamic Cone penetration Test), simpler and faster than conventional tests, has recently on rise. However, it is also an analog that measures data manually and has several disadvantages such as history management and data verification. The IoT-based DCPT system developed in this study combines digital wire sensors, mobile phones, and Bluetooth with conventional DCPT. Compare to conventional test methods, IoT-based DCPT has advantages such as performance time, single-person measurement, low cost, mobile-based management, and real-time data verification. In addition, a test bed was built to verify IoT-based DCPT. The test bed was built under similar conditions to the actual earthworks site through roller equipment. DCPT data obtained from 322 stations. As a result, IoT-based DCPT showed good performance, and the test bed was also showed stable results as the compaction was carried out.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• 2007.11a
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• pp.219-224
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• 2007

As use of construction equipment has been increasing continuingly, the proportion of equipment expense to the total construction cost has become higher. However, there is a difference between the equipment expenses section in 'Poom-Sam' and practical data, because 'Poom-sam' does not consider non-working days due to weather conditions, legal holidays and management conditions. Therefore, 'Poom-Sam' does not present a reasonable standard for estimating construction equipment expenses. In this study, to estimate realistic construction equipment operating hours, firstly, construction equipment was classified according to work, and weather conditions, in which each work could not be executed, were established. Then, weather data on Seoul and Busan(2004${\sim}$2006) and legal holidays were analyzed to suggest annual standard operating hours. The annual standard operating hours of earthmoving & excavating, compaction, and drilling equipment was estimated to be 1,430 hours, and lifting equipment, concrete paving equipment, asphalt paving equipment, concrete equipment, and crushing & conveying equipment were estimated to be 2,124 hours, l,156hours, 1,188hours, 1,688hours, and 2,152hours respectively.

• Journal of the Korean GEO-environmental Society
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• v.18 no.11
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• pp.13-18
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• 2017

In a banking process for construction of a complex, non-compaction construction has been applied in most sites, which is a method that soils are compacted by the equipment load without being compacted separately. However, there are no specific descriptions in the construction manual or specifications, so it is unclear to evaluate the excavation volume. Hence, this study is a basic study to compare the soil conversion factor at a design stage and the actual soil conversion factor of a banking ground under a non-compaction condition in order to examine the feasibility in constructing the ground for construction of the complex and to examine appropriateness of the earth work in the site by conducting an indoor, field, and load-settlement test and proposing a reasonable soil conversion factor. Under the non-compaction condition, the soil conversion factor C is set to be 1.0 at the design stage, but the result of the field test was 0.86 which is smaller than the value at the design stage. It was expected that this result would increase the banking volume, and the construction result actually showed a difference in the banking volume. Therefore, for the baking ground under the non-compaction condition, it is necessary to apply the value C suitable for the site condition after performing test by considering the site's condition and the banking height.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.41 no.9
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• pp.85-95
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• 2004

As the design complexity increases, it is a major problem that the size of test pattern is large and power consumption is high in scan, especially system-on-a-chip(SoC), with the automatic test equipment(ATE). Because static compaction of test patterns heads to higher power for testing, it is very hard to reduce the test pattern volume for low power testing. This paper proposes an efficient compression/decompression algorithm based on run-length coding for reducing the amount of test data for low power testing that must be stored on a tester and be transferred to SoC. The experimental results show that the new algorithm is very efficient by reducing the memory space for test patterns and the hardware overhead for the decoder.

• International Journal of Highway Engineering
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• v.8 no.3 s.29
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• pp.21-28
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• 2006

Field or laboratory wheel tracking tests have been employed for the evaluation of the rutting potential of asphalt paving mixtures. Compared to field tests, laboratory wheel tracking tests are much less expensive and more manageable for most road projects. However, most test laboratories are not equipped to perform such tests because there does not exist any standard test procedure, and the required equipment is rather expensive. Futhermore, the size of test specimens and the relatively large quantity of test mixture required present difficulties for laboratory specimen mixing and compaction. This paper describes a project conducted to study the feasibility of replacing wheel tracking testsby a repeated-load creep test for rutting potential evaluation. Comparisons were made between the results of the two tests for different test temperatures, loading speeds and applied pressures. Three types of asphalt mixtures were studied in the test program. Favorable conclusions concerning the use of the repeated-load test for rutting potential evaluation were drawn based on the findings of the experimental test results. The correlation between the two types of tests was found to be good for all threeasphalt mixtures. Adopting the repeated-load creep test would lead to cost savings since it employs standard test equipment already available in most laboratories. It would also result in substantial time savings due to the much smaller quantity of mix needed, and the ease in specimen preparation.