• Journal of the Korea Institute of Building Construction
• /
• v.11 no.6
• /
• pp.547-556
• /
• 2011

The primary factors affecting concrete sulfate resistance are the chemical composition of the Portland cement, and the chemistry and quantity of mineral admixtures. To investigate the effect of those on the sulfate attack, the testing program involved several different mortar mixes using the standardized test, ASTM C1012. Four different cements were evaluated, including one Type I cement, two Type I-II cements, and one Type V cement. Mortar mixes were also made with mineral admixtures, as each cement was combined with three different types of mineral admixtures. One Class F fly ash, one Class C fly ash, and one ground granulated blast furnace slag (GGBFS) were added in various percent volumetric replacement levels. Expansion measurements were taken and investigated with the expansion criteria recommended by ASTM.

• Journal of Korean Society of Forest Science
• /
• v.104 no.4
• /
• pp.615-621
• /
• 2015

This study was conducted to analyze accessibility and reduction effect of forest operations cost before and after forest road construction based on actual silvicultural operations in 5 regional forest service(8 management planning district) where forest operations was enacted consistently. The result show the accessibility and the reduction effect of the operation cost, the accessibility of forest operation area within 500 m from forest road or public road increased about 3.2 times after the forest road construction. The reduction effect of the operation cost was averagely 576,000 won/km/year. According to the results, forest road had an effect on improvement of accessibility and reduction effect of forest operation cost. This result could be offered basic information to support policy of forest road expansion.

• Journal of the Korea Institute of Building Construction
• /
• v.8 no.5
• /
• pp.85-91
• /
• 2008

Prepacked concrete has recently been used in the special constructions fields such as underwater concrete work, heavy-weight concrete work, underground structure work, partial repair works for damaged reinforced concrete structures. and polymer-modified mortars have been employed as grouting mortars for the prepacked concrete. The purpose of this study is to recommend the optimum mix design of polymer-modified grouting mortars for prepacked concrete. Polymer-modified mortars using SBR and EVA emulsions as admixture of grouting mortars for prepacked concrete are prepared with various mix proportions such as sand-binder ratio, fly ash replacement ratio, polymer-binder ratio. and tested for flowability, viscosity of grouting mortars, bleeding ratio, expansion ratio, flexural and compressive strengths of grouting mortars and compressive and tensile strengths of prepacked concretes. From the test results, it is apparent that polymer-modified mortars can be produced as grouting mortars when proper mix design is chosen. We can design the mix proportions of high strength mortars for prepacked concrete according to the control of mix design factors such as type of polymer, polymer-binder ratio, sand-binder ratio and fly ash replacement ratio. Water-binder ratio of plain mortars for a constant flowability value are in the ranges of 43% to 50%. SBR-modified mortar has a little water-binder ratios compared to those of plain mortar, however, EVA-modified mortar needs a high water-binder ratio due to a high viscosity of polymer dispersion. The expansion and bleeding ratios of grouting mortars are also controlled in the proper value ranges. Polymer-modified grouting mortars have good flexural. compressive and tensile strengths, are not affected with various properties with increasing fly ash replacement to cement and binder-sand ratio. In this study, SBR-modified grouting mortar with a polymer-binder ratio of 10% or less, a fly ash replacement of 10% to cement and a sand-binder ratio of 1.5 is recommended as a grouting mortar for prepacked concrete.

• Journal of the Korea Institute of Building Construction
• /
• v.19 no.1
• /
• pp.59-66
• /
• 2019

In this study, the effects of blast furnance slag cement and frost-resistant accelerator on shrinkage properties and shrinkage properties of mortar were examined. As a result, the addition of the frost-resistant accelerator to both OPC and BB has a small effect on the flash properties of mortar and the compressive strength increases from the early ages. In addition, when a frost-resistant accelerator is used in excess of the standard usage amount, it is necessary to examine the relationship of the expansion behavior at the early age, especially, between the compressive strength development and the expansion property. And it was confirmed that the addition of the frost-resistant accelerator tended to increase the shrinkage of mortar using the OPC and BB. With the addition of the frost-resistant accelerator, the amount of pores with a diameter of under the 30nm, especially, the amount of pores with a diameter of 20 to 30nm and the amount of pores with an ink-bottle decrease, and the shrinkage increases. And it is considered that a change in the amount this range of pores has a large effect on the shrinkage property.

• Journal of the Architectural Institute of Korea Structure & Construction
• /
• v.34 no.5
• /
• pp.19-26
• /
• 2018

A civil-military facility sharing project is a part of mutual cooperative efforts, which enables the military to use any civilian (local government or company) or a civilian to use any military facility. Such facility sharing project may reduce or clear possible conflicts with the local residents in the surrounding area of a military facility while being available to save budgets for new construction or maintenance of a defense or military facility. Various measures have been proposed for institutional resolutions on conflicts with the local residents in the surrounding area of a military facility. This study collects and organizes previous cases of the civilian-military facility sharing projects, and analyzes the characteristics of such cases based on the project types. In addition, by organizing and proposing the project characteristics, plans (ideas) and determination criteria to expand and vitalize are presented regarding the project types having restrictions. AHP technique is employed to research on the matrix for the project feasibility determination. Also, the opinions organized through the cause analysis are categorized and presented as a project for the expansion and vitalization of future project. According to the rearch result, Type I, II and III are determined to be projects that can be implemented without difficulties. Type IV, on the other hands, is determined as not illegal, yet inadequate so that some legal and institutional complements are required to expand and vitaliza this facility sharing project.

• Journal of the Korea Institute of Building Construction
• /
• v.21 no.1
• /
• pp.71-78
• /
• 2021

The spread of COVID-19 and the advent of the Fourth Industrial Revolution have significantly affected the nature of college education causing many changes to the way it is conducted. One of these changes is the expansion of online education. The purpose of this study was to analyze the difficulties experienced by learners due to the transition to rapidly expanding online education at domestic universities, and to seek ways to support their learning through this new online platform. Results of a questionnaire showed that learners experienced difficulties in their interactions with professors because of the rapid transition to online education without adequate preparation. It was determined that there were not enough opportunities for communication between learners and professors as a result of non-face-to-face online education, and that learners did not receive Q&A or feedback quickly enough. The study also examined ways to ways to improve the effectiveness of online learning. Students showed a high preference for items such as "appropriate guidance regarding announcements such as lecture schedules," "providing lecture notes as learning materials."

• Journal of the Korean Recycled Construction Resources Institute
• /
• v.10 no.1
• /
• pp.9-14
• /
• 2022

Most of the existing research on ferronickel slag has focused on its potential as aggregate and fine aggregate, this study was conducted focusing on the potential of ferronickel slag powder as a concrete admixture. For concrete, which fly ash, blast furnace slag, and FSP were mixed with each 10 % type the reactivity was evaluated by applying ASTM C 1260 of the United States. As a result, compared with the control group, the expansion rate of fly ash decreased by 8.43 % and that of fine blast furnace slag powder decreased by 14.46 %, while the expansion rate of ferronickel slag decreased by 49.40 %. it was confirmed that ferronickel slag can sufficiently be replaced existing supplementary cementitious admixtures such as fly ash and blast furnace slag in terms of suppressing the reactivity of aggregates. However as a result of SEM analysis, ettringites were generated, and additional research about how it affects concrete is needed.

• Journal of Korean Port Research
• /
• v.7 no.2
• /
• pp.37-60
• /
• 1993

Because of the rapid growing traffic volumes of cargo, especially between Seoul and Inchon, and lack of investment into transport infrastructure in the past, in Kyong-in area have suffered from the serious traffic congestion in the public-road and the express-way network, But the further expansion of the traffic volume in near future is difficult due to burden of the higher expansion of the traffic volume in near future is difficult due to burden of the higher construction cost. Although the traffic congestion on the Kyung-in railway, is not very serious comparing with the road sector, the shortage of capacity on some main lines becomes emerged as a problem as railway traffic has increased. Unlike these two modes, the water transport, which has been paid relatively less attention for commodity transport in Kyong-in area, has not any constaint in this respect. Han river has been used as a water transport route in Chosun Dynasty which is called Cho-wun. This paper therefore aims to propose the availability of Han river as the alternative water transportation mode, in order to decrease the congestion between Seoul-Inchon by considering the construction of Kyong-in artificial water channel in near future. In this paper, we investigate the availability of Nanji-do as the physical distribution depot connecting with the circulation express way in the national capital distribution depot connecting with the circulation express way in the national capital. We also estimate the traffic volume by using the push-barge carrier (300DWT) in the same channel through the simulation under some assumptions such as ship's turnaround time, speed, etc.

• International conference on construction engineering and project management
• /
• 2015.10a
• /
• pp.54-55
• /
• 2015

Increase of impervious areas due to expansion of housing area, commercial and business building of urban is resulting in property change of stormwater runoff. Also, rapid urbanization and heavy rain due to climate change lead to urban flood and debris flow damage. In 2010 and 2011, Seoul had experienced shocking flooding damages by heavy rain. All these have led to increased interest in applying LID and decentralized rainwater management as a means of urban hydrologic cycle restoration and Natural Disaster Prevention such as flooding and so on. Urban development is a cause of expansion of impervious area. It reduces infiltration of rain water and may increase runoff volume from storms. Low Impact Development (LID) methods is to mimic the predevelopment site hydrology by using site design techniques that store, infiltrate, evaporate, detain runoff, and reduction flooding. Use of these techniques helps to reduce off-site runoff and ensure adequate groundwater recharge. The contents of this paper include a hydrologic analysis on a site and an evaluation of flooding reduction effect of LID practice facilities planned on the site. The region of this Case study is LID Rainwater Management Demonstration District in A-new town and P-new town, Korea. LID Practice facilities were designed on the area of rainwater management demonstration district in new town. We performed analysis of reduction effect about flood discharge. SWMM5 has been developed as a model to analyze the hydrologic impacts of LID facilities. For this study, we used weather data for around 38 years from January 1973 to August 2014 collected from the new town City Observatory near the district. Using the weather data, we performed continuous simulation of urban runoff in order to analyze impacts on the Stream from the development of the district and the installation of LID facilities. This is a new approach to stormwater management system which is different from existing end-of-pipe type management system. We suggest that LID should be discussed as a efficient method of urban disasters and climate change control in future land use, sewer and stormwater management planning.

• Journal of the Korea Institute of Building Construction
• /
• v.24 no.3
• /
• pp.297-308
• /
• 2024

This study presents a novel approach for evaluating fire-induced damage depth in concrete. The methodology leverages the principle that exposure to high temperatures causes internal expansion within concrete, leading to increased voids and microcracks in the damaged zones. This heightened porosity results in greater absorption rates compared to undamaged areas. By immersing fire-damaged concrete samples in water and subsequently monitoring the drying process, the depth of damage can be assessed. Differences in drying rates and color variations between damaged and undamaged areas serve as visual indicators for determining the extent of the damage. Experimental results from this water immersion method revealed damage depths of 38.7mm and 37.5mm for two different concrete mixtures. These measurements notably surpass the damage depths estimated using traditional phenolphthalein-based methods. This discrepancy suggests that utilizing the absorption rate principle, which is directly linked to the physical changes caused by thermal expansion, offers a more accurate and sensitive assessment of fire damage depth compared to methods relying solely on the presence of Portlandite for colorimetric indication.