• Journal of the Korean GEO-environmental Society
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• v.16 no.11
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• pp.13-19
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• 2015

Construction materials using soil which is the most common material around us have many advantages, but their long-term durability and sensation of walking as pavements have problems. Therefore, they are used after compaction or mixed with various hardening agents such as lime and cement for strength enhancement. However, studies on the behavior of pavement materials mixed with environment-friendly hardening agents or admixtures to improve walking property are still insufficient. In this study, therefore, in order to evaluate the appropriate mixing ratio and field application characteristics of pavement materials using mixed soils with environment-friendly hardening agents and natural materials such as wood chips, mechanical tests were performed to evaluate the rational mixing ratios and the ball test was performed as an elasticity test to evaluate the field applicability. The results suggest that the content of wood chips should be selected at 1.5% or lower according to the purpose of the structure, and the hardening agent at 10~15%. The evaluation results for GB/SB coefficient ratio which indicates the walking property show that the appropriate mixing ratio of the hardening agent in terms of the sensation of walking is 15% of lower, but different mixing ratios should be chosen according to the proportion of wood chips.

• Journal of the Korean Recycled Construction Resources Institute
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• v.4 no.3
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• pp.322-329
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• 2016

This study is about the method to control the quality of material used to repair leakage and crack of concrete structure and suggests the "Temperature Stability Test Method" as a follow-up study. In the result of performance evaluation for 45 samples of 15 types in 5 series, the temperature stability test showed different material changes including rolling down, volume change, and color change as they are frozen and melt repeatedly in the somewhat extreme conditions at low($-20^{\circ}C$) and high($60^{\circ}C$) temperatures, where 13 samples (approx. 29%) and 32 samples (approx. 71%) showed leakage, respectively, in the permeability test to evaluate leakage. This result shows the enough importance of setting the quality control criteria of leakage repair material currently used to maintain concrete structures considering the temperature conditions, and proves the applicability of the Temperature Stability Test Method as a standard test method to ensure long-term durability of concrete structure.

• Journal of the Korea Institute of Building Construction
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• v.11 no.1
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• pp.51-59
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• 2011

With the increased demand for membrane structures in recent years, there have been many studies of their mechanical properties, to the extent that such structures have become recognized as independent structures with a level of safety and durability comparable to those of other general structures. But in reality, the study for the maintenance of membrane structures has not been as active. In particularly, the study of watertightness from the perspective of maintenance has been very limited. Accordingly, a study on securing watertightness performance and the guidelines for maintenance is necessary. In this study, through a case study of water leakage accidents in membrane structures overseas, causes of leakage were selected from the membrane material itself, joint parts and open door of roof part in membrane structure. The water leakage and deterioration elements were analyzed from those leakage causes. The degree of importance of the water leakage and deterioration index was also designated using the AHP (Analytic Hierarchy Process) method. As a result, the basic technical index was suggested for the maintenance of the roofs of large-span membrane structures to prevent water leakage. This index will be used to make a guideline for the long-term maintenance of the roofs of large-span membrane structures.

• Journal of Korean Society of societal Security
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• v.3 no.2
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• pp.33-39
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• 2010

This study is to reduce the rate of drowning accident by using of buoyancy bag. People are exposed to the high risk of drowning accident when they have water leisure activities due to the lack of safety mind-set and shortage of safety products. In case of drowning accident, the rescue action is normally depending on the other people's assistance. Therefore, rescue activities which relyn the people doesn't improve the ratio of survival in the drowning accidents. The submarine specialists should use the buoyancy products to rescue the people in the drowning accident. The citizen can carry portable buoyancy product in the automobile as well as by hands anywhere and anytime. It will be effective rescue tool to save his/her life in the emergency. In addition, it will contribute to rescue other's life because it can be used immediately. There are 3 positive characteristics on the buoyancy bag. First, it is convenience. Documents and other stuffs can be kept in the bag. Second is safety. The material of buoyancy is placed in the inner of the bag. It is possible to float the person whose weight is 90 kg. Lastly, it is durability. It can be used long-term because the outer of the bag is made of anti-water material and anti-water zipper. As a result of performance analysis, it is evident that the buoyancy bag can be used to rescue the people in the drowning accident as a indirect rescue tool compared with the current other rescue products. It is recommended that the design of outer box and performance of buoyancy are required to be improved in order to contribute more to rescue people in the accident.

• Journal of the Korea Concrete Institute
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• v.17 no.5 s.89
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• pp.793-801
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• 2005

This study investigates fundamental properties of recycled aggregate concrete which incorporated 100% recycled coarse aggregate and various amount of recycled fine aggregate. In addition, for the purpose of the improvement of long term strength and durability, a part of cement was replaced with fly ash. Compressive strength and resistance to chloride ion penetration and carbonation were investigated. When the coarse aggregate was completely replaced with the recycled the replacement ratio of the fine aggregate with the recycled was recommended to be limited below 60% in the consideration of strength. The strength of the steam-cured specimen was very comparable to the wet-cured at 28 days. As fly ash content increased the resistance to chloride ion penetration was increased. The chloride ion penetrability based on the charge passed was found to be low at 21 days and very low at 56 days, respectively. Carbonation depth and carbonation velocity coefficient increased as the fly ash content increased and the relationship between the carbonation depth and recycled fine aggregate replacement ratio was not clear. Up to 28days, however, the measured carbonation depth was mostly less than 10mm which could be considered as low.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.11
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• pp.9-18
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• 2020

Recently, studies of integrated management platform and performance-based maintenance decision-marking systems have proceeded to the efficient management of port facilities. The purpose of this study was to manage and operate port facilities based on performance and to provide long-term durability and budgetary execution. Thus, it is essential to secure basic data to be analyzed in an integrated platform and decision-marking system. This study derived the data linkage measures to secure port facility design and management information. The target of deriving the data linkage was the POMS (Port Facility Management System) currently in operation by the MOF (Ministry of Oceans and Fisheries). To derive data linkage, analyze the database of POMS and select the data required for the operation-integrated platform and decision-marking system. The final data linkage target was determined by compiling the requirements of the relevant experts and selecting the final target of three groups (port and facility information, management information, and user information). As a result, the API interface design was prepared for detailed linked data and data linkage framework between the linkage data of POMS. The provision of real-time data linkage between POMS and integrated platform is expected to improve the operational efficiency of the integrated platform.

• Journal of the Korean Institute of Gas
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• v.21 no.5
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• pp.36-44
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• 2017

The small commercial fuel cell is a new energy system that produces electricity and heat through electrochemical reaction between air and hydrogen. In Korea, hundreds of domestic small commercial fuel cell systems have been installed and operated every years and many parts in fuel cell systems depend on overseas products. KOGAS(Korea Gas Corporation) has developed the fuel processor which is an important part of fuel cell system and has evaluated the long-term durability. And KOGAS has evaluated domestic and overseas NG blower and fuel processor connected to NG blower. The fuel processor developed by KOGAS have maintained an efficiency of 76% and constant performance over 3,000 hours. The NG blower developed in Korea showed similar characteristics as overseas NG blower in the evaluation of power consumption according to rear pressure and outside temperature. The fuel processor module, fuel processor connected to BOP showed excellent performance.

• Journal of Korean Tunnelling and Underground Space Association
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• v.20 no.2
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• pp.469-483
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• 2018

Steel bars have been widely used as the primary reinforcement for Precast Segmental Concrete Lining for TBM Tunnels. Previously, studies have been carried out to gauge the potential for steel fiber reinforcement to replace the use of steel bar reinforcements in the segmental lining to reduce the amount of the steel bar reinforcement. Steel fiber reinforcements have been investigated and widely applied to SFRC TBM linings to improve the constructability of SFRC TBM linings worldwide. However, the steel fiber reinforcement often caused punctures to the water membranes inside tunnel lining and had long-term durability deterioration issues caused by steel corrosion, as well as cosmetic problems. Therefore, this paper sought to gauge the potential of synthetic fiber reinforcements, which have proven to be very attractive substitutes for steel fiber reinforcements. This study analyzed the performance of both steel and synthetic fiber reinforcements in segmental linings and evaluated the applicability of the fiber reinforcements to the TBM Precast Concrete Segmental Linings of TBM tunnels. As a conclusion, this study demonstrates that the potential use of steel and synthetic fibers in various combination, can substitute the rebar reinforcement in the concrete mix for segmental concrete linings.

• Journal of Korean Society of Environmental Engineers
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• v.38 no.7
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• pp.387-394
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• 2016

Commercial 28 algae removal technologies that have been applied in domestic rivers and lakes with green tide were investigated, analyzed and classified. The classification of algae removal technologies was based on the three criteria (i.e., principle, flow rate of water body, and application period). Also, algae removal technologies were evaluated in terms of cost effectiveness, field applicability, effect durability, and eco friendliness. From the analysis results, technologies using physical, chemical, biological, and convergent controls were 32.2%, 25%, 21.4%, and 21.4%, respectively. The 75% of technologies have been applied to stagnant water body (${\leq}0.2m/s$). Also, algae harvesting ship with dissolved air flotation, conveyor belt and filtration processes and natural floating coagulant were found to have better field applicability, compared to other technologies. However, proper algae removal technology in specific rivers and lakes should be chosen after the evaluation of long-term pilot scale field test. Also, development of energy and resource recovery technologies from algae biomass is warranted.

• Membrane Journal
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• v.25 no.4
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• pp.352-357
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• 2015

To determine the pervaporation separation characteristics of 1-butanol/water mixtures, PEI/PDMS hollow fiber membrane module commercialized by Airrane Co. was subjected to both lab and pilot tests. The 1% 1-butanol of 1-butanol/water feed mixture was used. The flux of $133g/m^2hr$ and separation factor of 23.4 at $30^{\circ}C$ were obtained whereas the $505g/m^2hr$ and 5.1 were measured at $50^{\circ}C$. When compared with the performance of the hollow fiber PDMS membrane by Nagasep Co., the higher flux of $10{\sim}20g/m^2hr$ was obtained by the module of Airrane Co. In order to realized the durability of Airrane Co. module, the long-term test of 35 days has been conducted and as a result, the flux $510{\sim}520g/m^2hr$ and separation factor 20~25 were maintained with the initial values.