• Proceedings of the Korean Society of Crop Science Conference
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• 2022.10a
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• pp.156-156
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• 2022

• Journal of the Korea Concrete Institute
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• v.23 no.3
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• pp.311-320
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• 2011

Fly ash (FA), byproduct from power plant has been actively used as mineral admixture for concrete. However, since bottom ash (BA) is usually used for land reclaim or subbase material, more active reuse plan is needed. Pond ash (PA) obtained from reclaimed land is mixed with both FA and BA. In this study, 6 PA from different domestic power plant are prepared and 5 different replacement ratios (10%, 20%, 30%, 50%, and 70%) for fine aggregate substitutes are considered to evaluate engineering properties of PA as fine aggregate and durability performance of PA concrete. Tests for fine aggregate of PA for fineness modulus, density and absorption, soundness, chloride and toxicity content, and alkali aggregate reaction are performed. For PA concrete, durability tests for compressive strength, drying shrinkage, chloride penetration/diffusion, accelerated carbonation, and freezing/thawing are performed. Also, basic tests for fresh concrete like slump and air content are performed. Although PA has lower density and higher absorption, its potential as a replacement material for fine aggregate is promising. PA concrete shows a reasonable durability performance with higher strength with higher replacement ratio. Finally, best PA among 6 samples is selected through quantitative classification, and limitation of PA concrete application is understood based on the test results. Various tests for engineering properties of PA and PA concrete are discussed in this paper to evaluate its application to concrete structure.

• Journal of the Korea Institute of Building Construction
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• v.23 no.6
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• pp.739-750
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• 2023

The quality certification for recycled aggregate is governed by the Construction Waste Recycling Promotion Act, overseen by the Ministry of Environment. The specific criteria for this certification are detailed in the Regulations on Quality Certification and Management of Recycled Aggregate, a mandate of the Ministry of Land, Infrastructure, and Transport. These regulations were initially enacted on April 10, 2006, and have undergone a total of 16 revisions to date, the most recent being on December 23, 2021. This paper delves into the revision history of these pivotal regulations pertaining to quality certification over the past 17 years, with a particular focus on the latest revision, which encompasses significant changes, including those in follow-up management. This analysis aims to aid stakeholders in the recycled aggregate sector, including 402 certified companies, in comprehensively understanding the government's strategic direction for quality certification and to encourage the recycling of construction waste by bolstering the quality certification process.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.329-332
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• 2008

Recently, land sand is being used more because of the deficiency of river sand. In this paper, in order to manufacture high strength concrete in the range of 70MPa, the effect of sand/aggregate ratio and adding fly-ash. As results, we could come to conclusion that the reduction of sand/aggregate ratio caused the increase of fluidity in the range of $37{\sim}45%$ and the maximum strength was 77MPa obtained at S/a=39%, which could be considered as optimum S/a. Besides, we could also get a conclusion that the larger amount of fly-ash increased the fluidity within 20% of replacement ratio (fly-ash to cement ratio) and the compressive strength at the age of 28days was equal to or larger than that of plane concrete, which represented no replacement by fly-ash, at the same range. from the results, it could be seen that the optimum replacement ratio of fly-ash was in the range of $10{\sim}15%$.

• Economic and Environmental Geology
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• v.54 no.5
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• pp.535-547
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• 2021

Aggregate is an essential construction material, and the demand is increasing every year. Aggregate has different properties in each region, and it is difficult to supply it over long distances due to its quantity and weight. For the stabilization of aggregate supply and demand, regional aggregate resource surveys have been conducted since 1993 in Korea. In this study, an aggregate resource survey was conducted in Goyang City to understand the characteristics of aggregate distribution as part of the annual regional aggregate resource survey in 2020. Goyang City has a high mountainous area to the east, and the southwestern part shows a topography where a wide flatland develops. It has 18 small streams originated from the eastern mountainuos area and 1 large stream Han River. The drilling data shows that thickness of the Quaternary deposits tend to deepen toward the south. The aggregate reserves are relatively abundant, the depth of the aggregates are relatively deep. Changes in the depth of the Quaternary deposits and the amount of aggregate in Goyang are seems to be closely related to the activities of the Han River rather than the sedimentation characteristics from the upstream to the downstream of the small streams. This characteristics show a similar tendency to the distribution of aggregates in adjacent regions to the west coast in Korea. Therefore, the regions that close to west coast have a high probability of aggregate reserves around relatively large-scale streams flowing into the west coast.

• Journal of the Korean Recycled Construction Resources Institute
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• v.4 no.3
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• pp.82-89
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• 2009

Recently, the study is progressing actively about manufacture skill of concrete for promoted recycled aggregate and concrete made into recycled aggregate in the construction production field. But, application and study about recycled fine aggregate insufficient compared to recycled coarse aggregate. So, in this study, it presents basic data for development of environmental load reduction fiber reinforcement recycled fine aggregate concrete by comparison and investigation about engineering properties and shrinkage cracking of fiber reinforcement recycled find aggregate concrete for increasing shrinkage cracking reduction and long term stability of environmental load reduction concrete used recycled fine aggregate. In the result of the study, compared to natural fine aggregate, a crack-extent increased by applying recycled fine aggregate, moreover, as a water cement ratio increased, the crack size increased, as well. In addition, it's shown that the specimen mixed with PVA and Nylon, among all kinds of fibers, showed the smallest crack size, so it's verified that the mix of fiber had an effect on decreasing crack-extent.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.12 no.3
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• pp.106-115
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• 2009

Knowledge about how to stabilize soil structure is essential to conserve soil systems and maintain various biogeochemical processes through soil. In urban area, soil structural systems are degraded with inappropriate management and land use and become vulnerable to erosion. We analyzed the structural changes of surface soils with different land uses, i.e., forests, parks, roadside green area, riparian area, and farmlands (soybean fields), in the Anyang Stream Watershed in order to find the factors influencing the stability of soil structure and the implication for better management of surface soil. Soil organic matter contents of other land use soils were only 18~52% of that in forest soils. Soil organic matter increased the stability of soil aggregates in the order of soybean fields < roadsides < riparian < parks < forests and also reduced soil bulk density (increased porosity). The lowest stability of soybean field soils was attributed to the often disturbance like tillage and it was considered that higher stability of park soils comparing to other land use soils except forests was owing to the covering of soil surface with grass. These results suggest that supply of soil organic matter and protection of soil surface with covering materials are very important to increase porosity and stability of soil structure.

• Journal of Soil and Groundwater Environment
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• v.26 no.6
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• pp.27-35
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• 2021

This study examined the possibility of reutilization of soil reclaimed from contaminated sites after completing remediation. The current status of soil remediation methods in Korea was reviewed and physicochemical properties of soil before and after remediation processes were examined to access the recycling possibility of reclaimed soils based on Recycling Aggregate Quality Standard. The most commonly practiced soil remediation techniques are soil washing, land farming, and thermal desorption. These techniques tend to deteriorate various soil properties including electrical conductivity(EC), organic matter content(OM), available P₂O₅, and cation exchange capacity(CEC). Evaluation of the properties of soil retrieved after each remediation process indicated soil washing may yield the most suitable soil for use as a filling, covering, back-filling, road pavement, and blocking materials, In addition, the soils reclaimed from land farming and thermal desorption have potential utility as a filling, covering and road pavement materials.

• Journal of KIISE:Databases
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• v.32 no.1
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• pp.43-55
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• 2005

Spatiotemporal databases support methods of recording and querying for spatiotemporal data to user by offering both spatial management and historical information on various types of objects in the real world. We can answer to the following query in real world: 'What is the average of volume of pesticide sprayed for cach farm land from April to August on 2001, within some query window' Such aggregation queries have both temporal and spatial constraint. However, previous works for aggregation are attached only to temporal aggregation or spatial aggregation. So they have problems that are difficult to apply for spatiotemporal data directly which have both spatial and temporal constraint. Therefore, in this paper, we propose spatiotemporal aggregate functions for analysis of spatiotemporal data which have spatiotemporal characteristic, such as stCOUNT, stSUM, stAVG, stMAX, stMIN. We also show that our proposal resulted in the convenience and improvement of query in application systems, and facility of analysis on spatiotemporal data which the previous temporal or spatial aggregate functions are not able to analyze, by applying to the estate management system. Then, we show the validity of our algorithm performance through the evaluation of spatiotemporal aggregate functions.

• The Journal of the Petrological Society of Korea
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• v.24 no.3
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• pp.253-272
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• 2015

The necessity of aggregate resources in Korea has been increased with a rapid economic growth since the 1990s. Construction activities have been increased drastically for last two decades. Such economic activities are much concentrated at big cities in Korea, and recently new neighbouring cities, such as multifunctional administrative city, enterprise city and innocity, are under construction at the surroundings of the cities. This new urbanization asked for an appropriate supply of raw construction materials such as cement, sands and gravels. The aim of this study is to understand and discuss the analysis and prospect of supply and demand of domestic sand and gravel. On the early years, 1990s, about 25% of the total consumption of these sands and gravels comes from riverine deposits; 20% to 25% from marine sands, 40% to 45% from forest rocks and the rest 5% to 15% from old fluvial deposits and crushed rocks. But nowaday the river aggregate, including both sands and gravels of a present river channel and those of the old fluviatile system are decreasing, while the crushed and forest aggregates and marine sand are now the main source of infrastructure resources. Thus it is increasingly necessary to investigate the forest and crushed aggregate resources potential in Korea where a current analysis indicate that the supply of riverine aggregates gradually decreases.