• Journal of the Korea Institute of Building Construction
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• v.14 no.1
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• pp.54-60
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• 2014

The purpose of this study is to examine whether cementitious powder separated from waste concrete can be used as an alternative raw material to limestone and reduce the usage of natural resource (limestone) and $CO_2$ emission based on recycling cementitious powder from waste concrete. Experiments actually analyzed the chemical composition of cementitious powder and performed hyperthermia analysis, measurement of free CaO and XRD analysis to measure the degree of recovery of hydration in the model of cementitious powder manufactured based on chemical composition. These were performed in each cementitious powder model at different calcination temperatures such as $900^{\circ}C$, $1200^{\circ}C$, $1300^{\circ}C$, $1400^{\circ}C$ and $1450^{\circ}C$. Through the experiments, it was found that the recovery of hydration was at a level which can be used as the alternative raw material for limestone, but the replacement ratio was directly affected by the degree of mixing of fine aggregate in less than $150{\mu}m$, which cannot be separated from cementitious powder. It was shown that there was no difference in the production of compounds involved in hydration at calcination temperatures of $1200^{\circ}C$ or higher. Therefore, to pursue the replacement of limestone and reduction of greenhouse gas by recycling cementitious powder, the development of technology to efficiently separate aggregate fine powder is required.

• Journal of Soil and Groundwater Environment
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• v.15 no.2
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• pp.47-54
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• 2010

Although the demands for the dredging work have been increasing due to social and industrial reasons including national plan for restoration of four major rivers, environmental standards or management guidelines for the dredged river sediment are limited. The suggested environmental standard for the beneficial use of dredged river sediment consists of two levels, recyclable and concern, and includes eight contaminants such as metals and organic contaminants. The systematic approach to remediate dredged river sediment is also suggested. The system consists of both washing and stabilization processes with continuous multi particle separation. In the early stage, the sediments are separated into two particle sizes. The coarse-grained sediment over 0.075 mm, generally decontaminated with less trouble, follows normal washing steps and is sent for recycling. The fine-grained sediments under 0.075 mm are separated again at 0.025 mm. The particles bigger than this second separation point are treated in two ways, advanced washing for highly contaminated sediments and stabilization for less. The lab test results show that birnessite and apatite are most effective stabilizing agents among tested for Cd and Pb. The most fine residues, down-sized by continuous particle separation, are finally sent for disposal. The system is tested for metals in this study, but is expected to be effective for organic contaminants included in the environmental standard, such as PAH and PCE. The feasibility test on the field site will be followed.

• Journal of the Korean Geotechnical Society
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• v.28 no.11
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• pp.53-67
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• 2012

In this research, stainless steel and heat-shrinkage tube were used for new TDR sensing line to solve the problems of ordinary TDR system. The new TDR line improved the sensitivity of water content and endurance, and reduced the data noise. The saturation degree test and acryl model test were done by revised TDR sensor. From the results, without additional data filtering and quantitative analysis, the raw data were separated into 3 zones; saturated, unsaturated and dried zones easily. In addition, the revised TDR sensor was installed in large-scale embankment model to perform the seepage test. The raw data of the model tests showed the distributed seepage behaviors and separated zones clearly, which were almost the same tendencies as the lab test results.

• Journal of the Korean Recycled Construction Resources Institute
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• v.4 no.1
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• pp.89-95
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• 2009

The current enforce decree of "The Act on the Promotion of Construction Waste Recycling" divides seventeen kinds of construction wastes by property and configuration. Mixed construction waste, one of them classified by the enforce decree, is composed two more than justified construction wastes except refuse soil and rock. In construction wastes justified by enforce decree of this law, most refuse concrete and asphalt concrete of construction wastes are recycled. As well as refuse metal is separated, sorted from bulk them, and merchandised for value. Finally this is used the secondary manufactured products. Even though combustible construction wastes like refuse wood, plastics, fiber can be recycled RDF(Refuse derived fuel) or RPF(Refuse plastic fuel) because of high caloric value and low heavy metal but most of them are discharged as mixed construction waste and then treated by treated by incineration and landfill. Therefore, to control construction waste flow efficiently, construction wastes are classifies first combustible, incombustible, mixed combustible, incombustible and etc. in this study. The combustible waste is consisted refuse wood, plastics, fiber and etc. and incombustible waste contains refuse concrete, asphalt, and etc. Mixed construction is construction waste that can not separate from mixed waste bulk with different kinds.

• Journal of the Korean Applied Science and Technology
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• v.30 no.4
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• pp.770-778
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• 2013

In this study, a liquid carbonation method was applied for producing precipitate calcium carbonate by liquid-liquid reaction. We recycled the recycling water of ready-mixed concrete, one of construction waste for use source of carbonate ion. A supernatant separated from the recycling water of ready-mixed concrete, as a result of ICP analysis of a cation, $Ca^{2+}$ was contained up to 1100 ppm. We used MEA as a $CO_2$ absorbent for the liquid carbonation. A precipitate $CaCO_3$ was produced at more than MEA 20 wt%. The precipitate $CaCO_3$ as a final product was separated and dried. The result of XRD was confirmed the generation of $CaCO_3$ to calcite structure.

• Geomechanics and Engineering
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• v.17 no.5
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• pp.413-420
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• 2019

The changes in earth pressure and ground settlement due to underground excavation near an existing retaining wall were studied experimentally according to the separation distance between the underground excavation and the retaining wall. In addition, this study attempted to experimentally prove that the arching phenomenon occurred during the construction of the underground space. A model tank having 120 cm in length, 160 cm in height, and 40 cm in width was manufactured to simulate underground excavation through the use of five separated base wall bodies. The variation of earth pressure on the retaining wall was measured according to the underground excavation phase through the use of 10 separated right wall bodies. The results showed that the earth pressure on the retaining wall was changed by the lowering of the first base bottom wall; however, the earth pressure was not changed significantly by the lowering of the third base bottom wall, since the third base wall had sufficient separation distance from the retaining wall. Lowering of the first base wall induced a decrease in the earth pressure in the lower part of the retaining wall; in contrast, lowering of the first base wall induced an increase in the earth pressure in the middle part of the retaining wall, proving the arching effect experimentally. It is necessary to consider the changes in earth pressure on the retaining wall in designing earth retaining structures for sections where the arching effect occurs.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2010.10a
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• pp.201-207
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• 2010

In this study, the SIP (Soil-cement Injected precast Pile) method among the Low-vibration & Low-noise pile driving methods was decided into study compensation. Ground vibrations by the SIP methods step by step divide and were analyzed. Quantitative response values and ground vibration equations with reliability were presented from findings of this study. Also, vibration responses that are occurred by the SIP method of construction were compared as quantitative with vibration responses by general method of construction that are presented in existent study. Ground vibration values by the SIP method correspond to level of 17 ~ 57% of values that are assumed by the Attewell & Famer's equation, respectively, and these result compares in reliability 50% and separated distance 10 ~ 50 m. Also, those values were analyzed that correspond to level of 14 ~ 96% of ground vibration values by the Prof. Park's equation, respectively. Construction limit extents, separation distances from vibration occurs position, were presented that can satisfy domestic criteria for vibration control for the SIP methods. Those presented in this paper were divided newly according to reliability.

• International Journal of High-Rise Buildings
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• v.5 no.1
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• pp.21-30
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• 2016

The structural efficiency of tall buildings heavily depends on the lateral stiffness and resistance capacity. Among those structural systems for tall buildings, outrigger system is one of the most common and efficient systems especially for those with relatively regular floor plan. The use of outriggers in building structures can be traced back from early 50 from the concept of deep beams. With the rise of building height, deep beams become concrete walls or now in a form of at least one story high steel truss type of outriggers. Because of the widened choice in material to be adopted in outriggers, the form and even the objective of using outrigger system is also changing. In the past, outrigger systems is only used to provide additional stiffness to reduce drift and deflection. New applications for outrigger systems now move to provide additional damping to reduce wind load and acceleration, and also could be used as structural fuse to protect the building under a severe earthquake condition. Besides analysis and member design, construction issue of outrigger systems is somehow cannot be separated. Axial shortening effect between core and perimeter structure is unavoidable. This paper presents a state-of-the-art review on the outrigger system in tall buildings including development history and applications of outrigger systems in tall buildings. The concept of outrigger system, optimum topology, and design and construction consideration will also be discussed and presented.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2015.11a
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• pp.99-100
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• 2015

Significant amount of bottom ash has been produced in the power plant located at southeast region of Korea, but those were abandoned in the pond site without any treatment. In these days, there is a strong move to enforce environmental regulations to protect surrounding nature, a lot of pressure is given to the power plant industry to remove hazardous chemicals from their waste material before landfill or site storage. The overall objective of this research is to separate hazardous chemicals from the bottom ash, and use it safely as sustainable construction material. In this specific study, magnetic separation of bottom ash was applied, and used as a fine aggregates to make mortar specimens. According to the results, it was found that the use of bottom ash decreased 28-day compressive strength. However, using non-magnetic bottom ash provides best results in terms of thermal conductivity, showing strong possibility to be used as heat insulating material.

• Journal of architectural history
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• v.23 no.2
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• pp.39-52
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• 2014

This study researched changes over time regarding the location and spatial characteristics of modern meteorological stations, and examined the characteristics of modern meteorological station construction using the location and spatial characteristics of the Busan Meteorological Station. First, meteorological stations were located in port areas, and then moved to high altitude areas for stable meteorological observation beginning in the transition phase. Here, office buildings and residences were joined, but were separated due to the increase in functions from the stabilization phase. Second, as for spatial composition, in the establishment phase, existing buildings were used, and the scale of newly constructed buildings differed according to time and area. However, after the Japan-Korea Annexation, with increased funds and increased observation equipment, floor plans subdivided by function started to appear. In the stabilization phase, space was subdivided with redundancy due to the increase in functions. In the wartime transition phase, '一' shaped floor plans with redundancy became the norm. Meanwhile, the location of the maritime customs where the first meteorological observations took place after the opening of the ports, and the location and construction of the Busan Temporary Observatory built in the meteorological observation transition phase (1905) were investigated. Also, through the investigation of the Busan Meteorological Observatory, newly constructed before 1934, the location and spatial characteristics of modern era meteorological observatories were studied.