• Journal of the Korea institute for structural maintenance and inspection
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• v.24 no.6
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• pp.67-76
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• 2020

This paper reports an experimental study to evaluate the flexural behavior of concrete beams reinforced using Fe based shape memory alloy (Fe-SMA) bars. For the experiment, a concrete beam of 200mm×300mm×2,200mm was produced, and a 4% pre-strained Fe-SMA bar was used as a tensile reinforcement. As experimental variables, type of tensile reinforcement (SD400, Fe-SMA), reinforcement ratio (0.2, 0.39, 0.59, 0.78), activation of Fe-SMA (activation, non-activation), and joint method of Fe-SMA bar (Continuous, welding, coupler) were considered. The electric resistance heating method was used to activate the Fe-SMA bar, and a current of 5A/㎟ was supplied until the specimen reached 160℃. After the upward displacement of the specimen due to the camber effect was stabilized, a three-point flexural loading experiment was performed using an actuator of 2,000 kN capacity. As a result of the experiment, it was found that the upward displacement occurred due to the camber effect as the Fe-SMA bar was activated. The specimen that activated the Fe-SMA bar had an initial crack at a higher load than the specimen that did not activate it. However, as with general prestressed concrete, the effect of the prestress by Fe-SMA activation on the ultimate state of the beam was insignificant.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2016.11a
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• pp.106-106
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• 2016

강의 산화 및 부식을 방지할 수 있는 표면처리 강판의 수요가 늘어나고 있다. 그 중 용융아연도금 강판은 뛰어난 경제성 및 도금성, 그리고 희생적 방식 특성으로 각광받고 있다. 자동차용 강판의 경우 도금 공정 이후의 표면 상태가 매우 중요하다. 도금 공정의 주된 표면 결함은 강판이 도금욕 내에서 이동 하면서 수반된 도금욕 내의 Zn-Fe-Al dross 입자에 기인한다. 도금공정 중 강판으로부터 용출된 Fe는 도금욕 내의 Zn 와 Al 과 반응하여 밀도가 높은 Bottom dross 나 밀도가 낮은 Top dross를 형성한다. 이에 본 연구에서는 강판으로부터 Fe의 용출속도에 미치는 도금욕 내 초기Fe 농도의 영향을 속도론적으로 평가하였다. 본 연구에서는 'Finger rotating method (FRM)' 방법론을 적용하였으며. 실험을 위해 수직 관상로 내부에 Zn-Al-Fe 시료를 장입한 알루미나 도가니를 위치시킨 후 온도를 $455^{\circ}C$로 설정하고, 지름 20mm의 Iron rod를 회전모터에 연결하여 Zn-Al-Fe 용탕에 침적한 후 회전시켰다. 실험 결과, 초기 Fe 함량과 용탕의 Fe포화 농도의 차이가 적을수록 Fe의 용출 속도는 감소하였으며 Dross 생성량 또한 적었다. 용탕 및 Iron rod 샘플 관찰 결과를 바탕으로 회전하는 Fe 시편으로부터 도금욕으로의 Fe 용출 메커니즘을 고찰하였다. 용출 모델을 토대로 모델링 한 결과, 용탕 내 Fe 농도 변화양상이 모델링 data와 실험 data가 동일한 양상을 보임을 확인 하였다.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.35 no.5
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• pp.287-297
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• 2022

This paper presents experimental and analytical studies on the lateral cyclic behavior of RC columns actively confined with iron-based shape memory alloy (Fe-SMA) strips. Based on the Anexperimental study, we investigated the effectiveness of active confinement through compression testings of concrete cylinders confined by Fe SMA strips and carbon fiber-reinforced polymer (CFRP) sheets. The test results showed that the specimens confined with Fe SMA strips significantly increased the deformation capacity of the concrete, even under lower confining pressures, compared to those specimensconfined with CFRP sheets. The experimental results were used to develop finite-element models of RC columns confined with Fe SMA or CFRP in their plastic-hinge region. After validating the proposed analytical model through comparison with the results from a previous RC column test, a series of lateral cyclic load analyses were carried out for the RC columns confined with Fe SMA and CFRP. The analytical results revealed that the lateral cyclic behavior of the Fe SMA-confined column was greatly enhanced in terms of deformation and energy dissipation capacities compared with tothat of the as-built and CFRP-confined columns.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.1B
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• pp.149-152
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• 2008

The reaction between iron oxide and ferrous iron is known to be the adsorption of ferrous iron onto the oxide surfaces that produces Fe(II)-Fe(III) (hydr)oxides and ferrous oxide oxidized to ferric ion which is the reducing agent of the target compounds. In our investigations on DS/S using ferrous modified steel slag, the results did not follow the trends. FeO and Fe(II), the major component of steel slag, were used to investigate the degradation of TCE. Degradation did not take place for the first and suddenly degraded after awhile. Degradation of TCE in this system was unexpected because Fe(II)-Fe(III) (hydr)oxides could not be produced in absence of ferric oxide. In this study, the characteristics of FeO/Fe(II) system as a reducing agent were observed through the degradation of TCE, measuring byproducts of TCE and the concentration of Fe(II) and Fe(III). Adsorption of ferrous ion on FeO was observed and the generation of byproducts of TCE showed the degradation of TCE by reduction in the system is obvious. However it did not correspond with the typical reducing mechanisms. Future research on this system needs to be continued to find out whether new species are generated or any unknown mineral oxides are produced in the system that acted in the degradation of TCE.

• Economic and Environmental Geology
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• v.36 no.1
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• pp.39-48
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• 2003

The removal of chromate from aqueous solution using finely ground pyrite and biotite was investigated by batch experiments and the kinetics and the mechanism of chromate reduction were discussed. The chromate reduction by pyrite was about hundred times faster than that by biotite and was also faster at pH 3 than at pH 4. When pyrite was used, more than 90% of initial chromate was reduced within four hours at pH 4 and within 40 min. at pH 3. However, more than 400 hours was taken for the reduction of 90% of initial chromate by biotite. The results indicate that the rate of chromate reduction was strongly depending on the amount of Fe(II) in the minerals and on the dissolution rate of Fe(II) from the minerals. The reduction of chromate at pH 4 resulted in the precipitation of (Cr, Fe)(OH))$_3$$_{ (s)}$, which is believed to have limited the concentrations of dissolved Cr(III) and Fe(III) to less than expected values. When biotite was used, amounts of decreased Fe(II) and reduced Cr(Ⅵ) did not show stoichiometric relationship, which implying there was not only chromate reduction by ferrous ions in the acidic solution but also heterogeneous reduction of ferric ions by the structural ferrous iron in biotite. However, the results from a series of the experiments using Pyrite showed that concentrations of the decreased Fe(II) and the reduced Cr(Ⅵ) were close to the stoichiometric ratio of 3:1. It was because the oxidation of pyrite rapidly created ferrous ions even in oxygenated solutions and the chromate reduction by the ferrous ions was significantly faster than ferrous ion oxygenation.

• Proceedings of the Korean Nuclear Society Conference
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• 1997.10a
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• pp.669-674
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• 1997

LAVA(Lower-plenum Arrested Vessel Attack) 실험은 중대사고시 고온의 노심 용융물이 냉각수가 존재하는 원자로 용기 하부 반구내로 재배치되는 경우 노심 용융물과 하부반구의 열적 거동 모사와 노심용융물과 하부 반구 사이의 구조 분석 및 고화 후의 용융물형상에 대한 관측을 통하여 노심용융물의 자연 냉각 현상을 규명하고자 하는 실험 연구이다. 원자로 용기 하부 반구를 1/8로 선형 축소한 반구형 반응 용기 내부로 $Al_2$O$_3$/Fe Thermite 용융물을 주입하여 용융물과 하부 반구 사이의 구조 및 하부 반구의 열적 거동을 분석하는 실험을 2회 수행하였다. 각각 20, 40kg의 $Al_2$O$_3$/Fe Thermite 용융물을 주입시 킨 LAVA_PRE, LAVA-1 실험 결과 용융물 주입에 따른 하부 반구의 파손은 발생하지 않았으며, 유사한 실험조건에서 수행된 일본 ALPHA실험에 비해서는 하부 반구의 최대 온도가 500 K 이상 높게 측정되었고 냉각율 또한 현저히 낮게 나타났다. 이는 $Al_2$O$_3$/Fe Thermit 용융물중 과열상태의 Fe성분이 하부 반구와 용접되었기 때문으로 판단되며 보다 정확한 하부 반구의 열적거동을 모사하기 위하여 반구 시편에 대한 재료, 조직 검사를 수행하고 있다. 추후의 실험에서는 하부 반구 내외부의 압력 부하에 따른 반응 양상 및 Fe 용융물(금속용융물) 성분을 제거하고 순수한 $Al_2$O$_3$용융물(산화용융물) 만을 주입하여 용융물 성분에 따른 하부 반구의 열적거동을 분선 할 예정이다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.11
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• pp.186-195
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• 2016

We investigated phytoplankton and vertical inorganic nutrients at two stations around water of Ulleungdo and Dokdo in the East Sea, Korea. Nutrient addition experiments (+N, +P, +NP and +Fe) were also conducted to determine the growth response and nutrient consumption of the phytoplankton assemblage using the surface water of St. UD3 and St.50. In the field, although inorganic nutrients were low in the euphotic layer, these nutrients were increased at depths below 100 m. The total phytoplankton abundances in St. UD3 and St.50 were $4.9{\times}10^5cells\;L^{-1}$ and $1.9{\times}10^5cells\;L^{-1}$, respectively. The dominant species at St. UD3 was observed to be Raphidophyta Heterosigma akashiwo, Cryptophyta Crytomonas spp., and diatom Leptocylindrus danicus, while L. danicus and H. akashiwo including small diatom species Chaetoceros socialis were dominant at St. 50. In the nutrient addition experiments, phytoplankton growth (in vivo flourescence) in the +N and +NP treatment was 2-3 times higher than that in the +P treatment, indicating that the natural phytoplankton can respond to pulsed nutrient loading events. In addition, in vivo fluorescence in +Fe treatment was not statistically (p>0.05) different from that of the non-Fe treatments, indicating that the phytoplankton growth response in +Fe treatment was not significant. Dominant H akashiwo and L. danicus in the field showed a rapid response in nutrient additional bio-algal assay, particularly L. danicus in the +Fe treatments.

• Journal of the Korean Electrochemical Society
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• v.5 no.3
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• pp.125-130
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• 2002

An attempt was made for the application of porous reticular metal to a heat dissipation material in semiconductor process. For this aim, the electrodeposition of Fe/Ni alloy on the porous reticular Cu has been performed to minimize the thermal expansion mismatch between Cu skeleton and electronic chip. Preliminary tests for the electrodeposition of Fe/Ni alloy layer were conducted by using standard Hull Cell to examine the effect of current density on the composition of alloy layer. It seemed that mass transfer affected significantly the composition of Fe/Ni layer due to anomalous codeposition in the electrodeposition of Fe/Ni alloy. A paddle type stirring bath, which was employed to control the mass transfer of electrolyte in the work, was found to allow the electrodeposition Fe/Ni with a precise composition. result showed that the thermal expansion of Fe/Ni alloy layer was much lower than that of pure copper. From the tests of heat dissipation by using the apparatus designed in the work the heat dissipation material fabricated in the work showed the excellent heat dissipation capacity, namely, more than two times as compared to that of pure copper plate.

• Journal of Soil and Groundwater Environment
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• v.14 no.6
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• pp.19-28
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• 2009

The acid mine drainage (AMD) and landfill leachates released into the subsurface environment can result in serious environmental problems like soil and groundwater contamination. The AMD and the leachates of landfill were known to contain many heavy metals. In this study, the author assessed the reactivity and ability of the FeS coated-ALC for the removal of contaminants (As, Cd, Cu, Pb, Ni, Zn, Al) in AMD and leachates in landfill. The synthetic nano-FeS and Autoclaved Lightweight Concrete (ALC) were used as reactive materials in the permeable reactive barriers(PRBs). The result of batch test indicated that synthetic nano-FeS can remove 99% of heavy metals for the 1hr of reaction time except for As and Ni(about 90%). However, the 80% of As and Ni was removed in column 1(FeS coated-ALC). The column 2(Ore FeS) removed more than 99% of heavy metals. The pH of the column 1 was increased from 3.51 to 6.39~6.50, and the pH with column 2 was increased from 3.51 to 9.20. As the result of this study, the author can surmise that the synthetic nano-FeS coated ALC will use as a very good reactive material of the PRBs to treat the contaminated groundwater with AMD and leachate of landfill.

• Economic and Environmental Geology
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• v.42 no.5
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• pp.487-494
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• 2009

The purpose of this study was to investigate the feasibility of As(V) reduction by aqueous Fe(II), and subsequent As(III) immobilization by the precipitation of As(III) incorporated magnetite-like material [i.e., co-precipitation of As(III) with Fe(II) and Fe(III)]. Experimental results showed that homogeneous As(V) reduction did not occur by dissolved Fe(II) at various pH values although the thermodynamic calculation was in favor of the redox reaction between As(V) and Fe(II) under the given chemical conditions. Similarly, no heterogeneous reduction of sorbed As(V) by sorbed Fe(II) was observed using synthetic iron (oxy)hydroxide (Goethite, ${\alpha}$-FeOOH) at pH 7. Experimental results for the effect of As(V) on the oxidation of Fe(II) by dissolved oxygen showed that As(V) inhibited the oxidation of Fe(II). These results indicate that As(V) could be stable in the presence of Fe(II) under the anoxic or subsurface environments.