• 콘크리트학회논문집
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• 제13권2호
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• pp.87-92
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• 2001

주물공장에서 발생하는 플라이애쉬는 현재까지 그 전부가 매립에 의존하고 있는 상태로 자원절약 및 산업폐기물의 유효이용이라는 측면에서 국가적인 손실이 아닐 수 없다. 따라서 산업폐기물의 유효이용, 콘크리트 제품 제조시 원가 절감, 콘크리트 제품의 품질개선 및 환경보존의 측면에서 플라이애쉬를 시멘트 대체재료로 사용할 수 있도록 이에 대한 연구가 필요하다. 본 연구에서는 주물공장의 폐기물인 플라이애쉬를 건설산업에 활용하는 방안을 수립하는 데 그 목적이 있다. 이를 위하여 주물공장에서 발생하는 플라이애쉬를 시멘트 대체재로 사용한 속빈 콘크리트 블록 및 콘크리트 벽돌을 제작하여, 한국산업규격에 규정한 요구조건에 대한 실험을 실시하였고 제반 특성을 조사하여 콘크리트 제품에 활용할 수 있는 방안을 제시하였다.

• Structural Engineering and Mechanics
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• 제86권4호
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• pp.431-441
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• 2023

The aim of this paper is to present a new sustainable ternary and quaternary binder by partially replacing ordinary Portland cement (OPC) with different percentages of supplementary cementitious materials. The motivation is to reduce our dependency on OPC to reduce CO₂ emission and carbon foot print. As the main substitute for the OPC, siliceous fly ash was used. Moreover, silica fume and nanosilica were also used. During examinations the main mechanical parameters of concrete composites, i.e., compressive strength (f_cm) and splitting tensile strength (f_ctm) were assed. The microstructure of these materials was also analysed. It was found that the concrete incorporating pozzolanic materials is characterized by a well-developed structure and has high values of mechanical parameters. The quaternary concrete containing: 80% OPC, 5% FA, 10% SF, and 5% nS have shown the best results in terms of good strength parameters as well as the most favourable microstructure, whereas the worst mechanical parameters with microstructure containing microcracks at phase interfaces were characterized by concrete with more content of FA additive in the concrete mix, i.e., 15%. Nevertheless, all concretes made on quaternary binders had better parameters than the reference one. It can be stated that sustainable concrete incorporating pozzolanic materials could be good substitute of ordinary concretes.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2002년도 가을 학술발표회 논문집
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• pp.613-620
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• 2002

Sand Compaction Pile(SCP) is a soil improvement method that a sand charge is introduced into the pipe, and the pipe is withdrawn part away while the sand pile is compacted and its diameter is enlarged. The sand used in this method should be of good quality. In Korea, crushed stone and washed sea sand are used frequently in SCP. However, use of these materials is restricted because of environmental problem and deficiency of supply. In the copper smelting process, about 0.7 million tons of copper slag are produced in Korea. The range of particle size distribution of copper slag is from 0.15mm to 5mm, so it can be a substitute for sand, and the relatively high specific gravity compared with the sand, is its characteristic. Copper slag is hyaline and so stable environmentally that in foreign country, such as Japan, Germany etc., it is widely used in harbor, revetment and offshore structure construction works. Therefore, in this study, the several laboratory tests were peformed to evaluate the applicability of copper slag as a substitute for sand of SCP. From the mechanical property test, the characteristics of sand and copper slag were compared and analyzed, and from laboratory model test, the strength of composite ground was compared and analyzed by monitoring the stress and ground settlement of clay, SCP and copper slag compaction pile. Specially, this study focused on the application of copper slag as sand substitute in SCP pilot tests based on laboratory tests results.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2008년도 추계학술발표대회 및 제15회 신소재 심포지엄
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• pp.43.2-43.2
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• 2008

• 한국재료학회:학술대회논문집
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• 한국재료학회 2008년도 추계학술발표대회 및 제15회 신소재 심포지엄
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• pp.41.2-41.2
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• 2008

• 한국환경복원기술학회지
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• 제7권2호
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• pp.46-51
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• 2004

In this paper, reinforcement of soil shear strength by bamboo(substitute materials simulating a root system) are evaluated by soil strength parameters(apparent cohesion(c) and internal friction angle(tan${\Phi}$)), using simple shear tester which clearly depicts shear deformation and controls soil suction. The results show that the internal friction angle does not change under various soil suction conditions but the apparent cohesion, which reach a peak in suction of 45cm$H_2O$ near critical capillary head, is effected by soil suction. And the reinforcement of soil strength by bamboo are expressed by apparent cohesion more than internal friction angle. In addition the increment of apparent cohesion by bamboo reached a peak in suction 45cm$H_2O$ too.

• 한국임상수의학회지
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• 제15권2호
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• pp.364-369
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• 1998

The purposes of the present study were to compare the effects of viscoelastic materials available in phacoemulsification in dogs and to evaluate $ARTZ^{\circledR}$ as their substitute. Six eyes from the healthy adult dogs were used in each group with different viscoelastic materials, $Healon$^{\circledR}, Viscoat^{\circledR}$ and $Occucoat^{\circledR} and ARTZ^{\circledR}$. The phacoemulsification was carried out with surgical micmscope(Leica M65l, Germany) and pbacoemulsiscation gystemGfidek 6000, Japan). $ARTZ^{\circledR}$ had lower pseudoplasocity than other viscoelastics. There was not significant difference in phacotime, rate of posterior capsule rupture, incidence of the intraocular inflammation among the viscoelastic materials. The corneal thickness in all groups was significantly increased in a day after operation and decreased gradually. However $ARTZ$^{\circledR}$ had more time to recover the preoperative thickness than the others. CoBiunctival congestion in the group with $ARTZ^{\circledR}$ was more severe but. there were no postoperative posterior capsule opacity and visual loss. The present study indirated that $ARTZ^{\circledR}$ could be used as viscoelastic material in dogs with respect to the vision after surgery.

• 한국발생생물학회지:발생과생식
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• 제21권4호
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• pp.441-448
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• 2017

Bisphenol-A(BPA) is a member of alkylphenol family, and shows adverse effects including reduced fertility, reproductive tract abnormalities, metabolic disorder, cancer induction, neurotoxicity and immunotoxicity. In the present study, we conducted Hershberger assay to evaluate whether the two candidates to replace BPA have androgenic or antiandrogenic activity. The assay was carried out using immature castrated Sprague-Dawley male rats. After 7 days of the surgery, testosterone propionate (TP, 0.4 mg/kg/day) and test materials (low dose, 40 mg/kg/day; high dose, 400 mg/kg/day) were administered for 10 consecutive days by subcutaneous (s.c.) injection and oral gavage, respectively. Test materials were BPA, isosorbide (ISO) and cyclohexanedimethanol (CHDM). The rats were necropsied, and then the weights of five androgen-dependent tissues [ventral prostate, seminal vesicle, levator ani-bulbocavernosus (LABC) muscle, paired Cowper's glands, and glans penis] and three androgen-insensitive tissues (kidney, spleen and liver) were measured. All test materials including BPA did not exhibit any androgenic activity in the assay. On the contrary, antiandrogen-like activities were found in all test groups, and the order of the intensity was CHDM > BPA > ISO in the five androgen-sensitive tissues. There was no statistical difference between low dose treatment and high dose treatment of BPA group as well as ISO group. In CHDM group, high dose treatment exhibited most severe weight reduction in all measured tissues. There was no statistical difference in androgen-insensitive tissue measurements, except BPA groups. Since the effects of ISO treatment on the accessory sex organs were much less or not present at all when compared to those of BPA, ISO could be a strong candidate to replace BPA. CHDM treatment brought most severe weight reduction in all of androgen-sensitive tissues, so this material should be excluded for further screening of BPA substitute selection.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2011년도 춘계학술발표대회
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• pp.52.1-52.1
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• 2011

In this work, the effect of the addition of bioactive glass in the biocompatibility and mechanical behavior of conventional TTCP/DCPA based bone cement were investigated. The cement was initially modified with chitosan and HPMC which cross-linked with citric acid to improved mechanical properties.The injectable bone substitutes were further modified by adding varying amounts of bioactive glass (0%, 10%, 20% and 30%) and its effects on the biocompatibility of the material were studied. Afterbio-glass powders were mixed with the optimized composition for HPMC and citric acid content,the IBS was incubated at $37^{\circ}C$ at different time intervals and showed progressive formation of HAp with increasing time. Mechanical properties like Vickers hardness and compressive strength were found to increase with the increasing amount of bioactive glass addition and that setting time was shortened. The fabricated IBS morphologies were further characterized using SEM. MTT assay was performed to check the cell cytotoxicity and cell proliferation for 1, 3 and 5 days. Cell morphology, adhesion and proliferation behavior of cell in the IBS by culturing MG-63 cells on the IBS for 20, 60 and 90 mins and 1, 3 and 5 days was also investigated. All the results showed increasing biocompatibility as the bioglass content increased. MTT results found the materials to be cytocompatible and SEM images showed that cells attached and proliferated successfully.

• Structural Engineering and Mechanics
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• 제88권2호
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• pp.141-157
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• 2023

In the present paper, the effect of recycled aggregates on the rheological and mechanical properties of self-consolidating concrete is investigated experimentally and numerically. Hence, the specimen with two types of recycled aggregates, i.e., known and unknown resistance origins, are utilized for the studied specimens. The experiments in this study are designed using the Box-Behnken method, which is one of the response surface methods. Input variables in mixtures include silica fume in the range of 5-15% as a percentage substitute for cement weight and recycled coarse and fine aggregates in the range of 0-50% for both series of recycled materials as a substitute for natural materials. The studied responses are slump flow, V funnel, compressive strength, tensile strength, and durability. The results indicate that the increase in the amount of recycled aggregates reduces the rheological and mechanical properties of the mixtures, while silica fume effectively improves the mechanical properties. In addition, the results demonstrate that the fine recycled aggregates affect the total response of the concrete significantly. The results of tensile and compressive strengths indicate that the mixtures including 50% recycled materials with known resistance origin demonstrate better responses up to 8 and 10% compared to the materials with unknown resistance origins, respectively. Recycled materials with a specific resistance origin also show better results than recycled materials with an unknown resistance origin. Durability test results represent those concretes containing recycled coarse aggregates have lower strength compared to recycled fine aggregates. Also, a series of mathematical relationships for all the responses are presented using variance analysis to predict mixtures' rheological and mechanical properties.