• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.10
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• pp.1199-1203
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• 2011

Nanocomposites were prepared through the compounding of rubber and clay. Measurements of the static and dynamic mechanical properties of different compositions over a temperature range $70-100^{\circ}C$ showed that the mechanical properties of these rubber/clay nanocomposites are superior to those of existing rubber materials. In this study, by using the parameter of the maximum Green.Lagrange strain appearing at certain locations, the relationship between fatigue life and maximum Green.Lagrange strain, and the correlations between test-piece tests and bench tests of actual rubber components are proved. In order to predict the fatigue life of rubber components at the design stage, a simple procedure of life prediction is suggested. The predicted fatigue lives of the rubber engine mounts agree fairly well with the fatigue lives determined experimentally.

• Journal of the Earthquake Engineering Society of Korea
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• v.3 no.2
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• pp.55-66
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• 1999

Eight RC bridge plers have been made on a 1/3.4 scale model and have been tested in a quasi-static cyclic load so as to investigate their seismic performance. The ultimate objective of this experimental study is to investigate the hysteretic behavior of reinforced concrete plers, which have been widely used for urban transportation facilities in Korea. Improtant test parameters are hoop ratio, axial load, load pattern, and etc. And noninear behaviors of test columns have been evaluated through their yield and ultimate strength, energy dissipation, ductility and load-deflection characteristics under quasi-static cyclic loads. From the quasi-static tests on 8 bridge piers, it is concluded that energy dissipation, ultimate strength and curvature for a given displacement factor ${\mu}={\Delta}/{\Delta}_y$ are higher for the seismically designed columns than for the nonseismically designed columns.

• Geotechnical Engineering
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• v.14 no.1
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• pp.5-14
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• 1998

In refuse landfill, long-term settlement is considerably dependent upon the biological decomposition of refuse which is distinguished from typical soil behavior. Two equations are combined in order to model long-term settlement behavior of refuse landfill caused by mechanical secondary compression and secondary compression caused by the decomposition of biolegradable refuse. It is suggested that mechanical secondary compression is linear with respcet to the logarithm of time. In order to estimate the settlement that occurs due. to the decomposition of biodegradable refuse, a mathematical model is used which theoretically conoiders the decomposition process related to the solubilization stage of biodegradable refuse solid. This model is based on hydrolysis process and expressed as first order kinetics. The proposed model is applied to Lysimeter compression data of an old refuse. This paper intends to propose the simplest mathematical model which effectively represents settlement caused by the solubilization stage of biodegradable refuse solid on decomposition process.

• Polymer(Korea)
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• v.31 no.2
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• pp.141-147
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• 2007

Dental properties of polymer composite loaded with hybrid filler of barium silicate (BaSi) and hydroxyapatite, which is a principal component of human bone material, were investigated. A visible light system was utilized to activate the acrylic resin matrix of the composite. Based on the experimental results, it was found that mechanical strength of the composite was consistently increased with an increase of BaSi content in the hybrid filler. And those value rose above the dental specification enough to apply for dental materials. However, abrasion resistance was slightly decreased with increasing BaSi content in the filler. Depth of cure value was 6 to 9 mm applicable for dental restoration irrelevant to hybrid filler composition. On the other hand, there was no strict trend between filler composition and polymerization shrinkage as well as degree of conversion.

• Journal of the Korean Recycled Construction Resources Institute
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• v.9 no.4
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• pp.413-418
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• 2021

In this study, as a basic study to use recycled limestone powder as a secondary product mixture for concrete, it was found that the compressive and flexural strengths were equal to or slightly improved compared to Plain up to 10% and 20% of the RLP mixing ratio, but the strength was rather decreased at 30% mixing. As a result of the heat of hydration experiment, as the RLP mixing rate increased, the heat of hydration decreased, and the elapsed time of the maximum heat was also delayed. As a result of the drying shrinkage test, as the fine powder RLP filled the internal pores of the cement mortar, the drying shrinkage decreased as the mixing rate increased. The compressive strength, water absorption rate, and compressive strength after freezing and thawing of the concrete block mixed with RLP 20% all satisfied the group standard criteria of the Korea Concrete Industry Cooperative Federation, confirming the possibility of use as a mixed material.

• Journal of the Korean Geotechnical Society
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• v.40 no.1
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• pp.39-46
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• 2024

Artificial recharge systems have been employed to solve drought problems due to global climate change. Despite the increased usage, the applications of artificial recharge systems are limited by clogging problems, which reduce recharge rates. In this study, the soil texture and mineral characteristics of alluvial soil in a planned artificial recharge system area were investigated to evaluate the possibility of chemical clogging during the injection of stream water. The primary minerals contained in the clastic particles are quartz, K-feldspar, plagioclase, and biotite, and the secondary minerals filling the pore space are illite, kaolinite and Fe-oxide. The fact that carbonate and sulfate are observed as secondary minerals in the pore space suggests that chemical clogging has not occurred by the interaction between the groundwater and surface water in the study area. Thus, monitoring soil properties, e.g., the formation and growth of secondary minerals in the pore space, is required to investigate the possibility of chemical clogging in artificial recharge systems.

• Journal of the Korean Institute of Gas
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• v.28 no.2
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• pp.7-16
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• 2024

This study presents investigation on the technical characteristics and field cases of the salt cavern storage method for large-scale hydrogen storage. The salt cavern storage method enables effective hydrogen storage compared to other methods due to the low porosity and permeability of the rock salt that constitutes the cavern, which is not likely to leak and requires a small amount of cushion gas for operation. In addition, there is no chemical reaction between rock salt and hydrogen, and multiple injection/withdrawl cycles can be performed making it effective for peak shaving and short-term storage. The salt cavern is formed in three stages: leaching, debrining, and filling, and leakage tests are conducted to ensure stable operation. Field applications are currently performing to meet industrial demand in the surrounding area of four sites in the UK and Texas, USA, and salt cavern operation is being prepared for energy storage in European countries such as Germany and France. The investigated results in this study can be utilized as a basic guideline for the design of future hydrogen storage projects.

• Journal of the Microelectronics and Packaging Society
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• v.15 no.3
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• pp.47-52
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• 2008

This investigation was performed in order to study the properties of deposition and layers by Silicon Dioxide, SiO2, as dielectric onto Via and Trench which have high Aspect Ratio (AR). Thus, in order to confirm these properties, three types of CVD, which were PECVD, PETEOS, and ALD, were selected. On the experiment each of the property sections was estimated that step overage of PECVD: <30%, PETEOS: 45%, ALD: 75% and the RSM of PECVD: 27.8 nm, PETEOS: 2.1 nm, ALD: <2.0 nm. As a result of this experiment for the property of electric film, ALD was valuated to be the most favorable outcome. However, ALD was valuated to have the least quality for the deposition rate. ALD deposition rate, $10\;\AA/min$ by $1\;\AA$/1cycle, was prominently lower than PETEOS, which had the deposition rate of $5000\;\AA$/min. Since electric film requires at least $1000\;\AA$ thicknesses, ALD was not suitable for the deposition rate. which is the most important component in a practical use. Therefore, in this particular study, PETEOS was evaluated to be the most suitable recipe.

• Journal of Korean Society of Environmental Engineers
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• v.29 no.3
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• pp.289-296
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• 2007

Porous media for sewage treatment were developed through a pyrolysis process of food wastes with loess in the study. This work was carried out in two consecutive stages; in the first stage, new porous media were prepared through a high temperature pyrolysis process, and then the resultant media were applied to a simple lab-scale sewage treatment process in the second stage. To determine the optimum operating conditions of pyrolysis and mixing ratio of materials, physical properties such as specific surface area, porosity and compressive strength of final products were analyzed. The removal efficiencies of TOC and COD were measured to evaluate the effectiveness of resultant porous media. As a result of the experiment, we found that the best mixing ratio of food wastes to loess was 1 : 1 at $1,100^{\circ}C$. Average porosity of the developed media was 37.0%, in which pore size ranged from 1 to $20{\mu}m$, showing quite vigorous microbial activation. After immersing the media into a reactor for sewage treatment for eight days, removal efficiencies of TOC and COD were 87.3% and 85.0%, respectively.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2018.10a
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• pp.69-69
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• 2018

벼룩이울타리(Arenaria juncea M.Bieb.)는 청열, 양혈, 허로기열, 골증, 수심작열, 도한 등의 약효가 있으며, 백색의 꽃이 취산화서로 아름답게 개화하여 조경소재로 이용가치가 높다. 본 연구는 벼룩이울타리의 육묘기술 개발을 위하여 2017년 6월 2일부터 7월 31일까지 8주간 수행하였다. 실험의 대조구는 200구 트레이에 원예상토를 충진하고 종자를 셀 당 3립씩 파종하여 무차광 조건에서 육묘하였으며, hyponex $500mg{\cdot}L^{-1}$를 2회 추비하였다. 토양 실험은 원예상토[$300-200-200mg{\cdot}L^{-1}$(N-P-K)]와 피트모스:펄라이트(3:1), 코코피트:펄라이트(3:1) 혼용토를 이용하였으며, 원예상토를 제외한 모든 토양은 0-0-0, 300-200-200, $600-400-400mg{\cdot}L^{-1}$의 비료를 첨가하였다. 종자는 셀당 1, 3, 5립을 파종하였고, 추비는 hyponex (6.5-6-19)를 0, 500, $1000mg{\cdot}L^{-1}$로 4, 6주차에 총 2회 잎이 충분히 젖을 정도로 살포하였다. 차광은 0, 55, 75%로 설정되었다. 벼룩이울타리 육묘의 결과, 토양 종류별로는 원예상토에서 초장이 가장 길었으며, 다음으로 피트모스 혼용토의 순이었다. 피트모스 혼용토에서 육묘한 유묘의 초장은 비료를 첨가하지 않은 처리구에서 길어지는 경향을 보였다. 경직경과 근장은 원예상토 단용구와 코코피트 혼용토가 피트모스 혼용토에 비해 양호하였다. 엽수는 상토(26.1 ea)에서 가장 많았고 다음으로 비료 코코피트 혼용토 $600-400-400mg{\cdot}L^{-1}$(22.9 ea)의 순이었다. 셀 당 파종립수를 달리하여 육묘한 결과, 초장은 파종립수가 적을수록 길었으며, 경직경과 엽수는 처리에 따른 유의적인 차이를 확인할 수 없었다. 추비 처리별로 전반적인 생육은 큰 차이는 보이지 않았으나, 경직경은 처리농도가 낮을수록 두꺼워지는 경향이었다. 엽수는 hyponex 처리시 무처리구에 비해 증가하는 경향을 보였으며, $500mg{\cdot}L^{-1}$ 처리구에서 가장 많았다. 차광정도에 처리에 따른 생육은 차광률이 높을수록 생육이 억제되는 경향이었다. 초장, 엽수 및 근장은 무차광에서 차광처리구에 비해 우수하였다. 경직경은 무차광구와 50% 차광구가 70% 차광구에 비해 증가하였다. 지상부, 지하부의 생 건체중도 무차광에서 가장 무거웠으며, 차광률이 증가할수록 감소하였다.