• 자원환경지질
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• 제32권6호
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• pp.575-584
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• 1999

Through alkaline hydrothermal activation processes, zeolite minerals were synthesized from fly ashes produced at Youngwol and Boryoung power plants. The syntheses were performed in a closed teflon vessel with a teflon-coated magnetic bar for continuous stirring during the reaction periods. The experiments were caeeied out at three different reaction temperatures ($100^{\circ}C$,$200^{\circ}C$, and $250^{\circ}C$), with varying NaOH concentations (0.5~8N) and reaction time (24 to 288 hours). Mineralogical characterization of the reaction products indicated that Na-p1, analcime, and hydroxysodalite were dominant zeolites formed from the both fly ashes at the given experimental conditions, The highest amount of zoelites produced from the Youngwol and Boryoung fly ash were:60 and 45wt%for Na-P1, 70 and 45wt% for analicime, 50 and 40wt% for hydroxysodalite, respectively. A small amount of zeolite A was present in NaP-dominant dample is about 250 meq/100g. This suggests the possibility of its utilization as an ion-absorbent.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2013년도 춘계 학술논문 발표대회
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• pp.85-86
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• 2013

Weakness of fine powder of blast furnace slags includes the decrease of initial intensity and delay of setting time. To solve this problem, there has been research on the alkali activation to induce hardening using alkaline chemical. However, the use of chemicals is dangerous and not cost effective, which can be solved by using recycled aggregates, one of construction wastes. The role of alkali activator can be substituted by alkali of non-hydrated cement included in recycled aggregates. In this study, the alkaline value of recycled aggregates will be evaluated through the comparison of molarity of sodium hydroxide (NaOH).

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2003년도 유체기계 연구개발 발표회 논문집
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• pp.541-546
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• 2003

Activated carbon was prepared from coffee wastes by chemical activation with $ZnCl_{2}$, NaOH and KOH. The coffee wastes was used as raw material. Preparation process involves the roasting of raw material and carbonization of roasted material followed by chemical activation. N2-BET surface areas of activated coffee char prepared by chemical activation was measured as $1,110{\sim}2,442m^{2}/g$. Removal of copper and chromium in solution by activated carbon was carried out and structural change of pore surface was observed by SEM.

• 폴리머
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• 제26권4호
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• pp.501-507
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• 2002

본 논문에서는 bisphenol-S (BPS)와 epichlorohydrin (ECH)를 NaOH의 촉매하에서 중합시켜 diglycidylether of bisphenol-S (DGEBS) 에폭시 수지를 합성하였다. IR, NMR spectra 분석, 그리고 원소분석에 의해 합성한 DGEBS 에폭시 수지의 화학구조를 확인하였다 산무수화물계 phthalic anhydride (PA)와 tetrahydrophthalic anhydride (THPA)를 경화제로 사용하여 DSC에 의한 열분석을 통하여 DGEBS 에폭시 수지의 경화 동력학과 유리전이온도 ($T_g$)를 고찰하였으며, TGA 열분석을 사용하여 경화된 시편의 열안정성을 측정하였다. 실험 결과 DGEBS/PA계의 경화 활성화 에너지 ($E_a$)는 DGEBS/THPA계보다 높았지만 ($T_g$), 열분해 개시온도 (IDT), 그리고 분해 활성화 에너지 ($E_t$)는 DGEBS/THPA계보다 낮았다. 이는 경화제의 ring strain에 의하여 DGEBS/THPA계의 가교 밀도가 증가하였기 때문인 것으로 사료된다.

• 한국재료학회지
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• 제23권11호
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• pp.643-648
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• 2013

Activated carbon (AC) was synthesized from rice husks using the chemical activation method with KOH, NaOH, a combination of (NaOH + $Na_2CO_3$), and a combination of (KOH + $K_2CO_3$) as the chemical activating reagents. The activated carbon with the highest surface area (around $2000m^2/g$) and high porosity, which allows the absorption of a large number of ions, was applied as electrode material in electric double layer capacitors (EDLCs). The AC for EDLC electrodes is required to have a high surface area and an optimal pore size distribution; these are important to attain high specific capacitance of the EDLC electrodes. The electrodes were fabricated by compounding the rice husk activated carbons with super-P and mixed with polyvinylidene difluoride (PVDF) at a weight ratio of 83:10:7. AC electrodes and nickel foams were assembled with potassium hydroxide (KOH) solution as the electrolyte. Electrochemical measurements were carried out with a three electrode cell using 6 M KOH as electrolyte and Hg/HgO as the reference electrode. The specific capacitance strongly depends on the pore structure; the highest specific capacitance was 179 F/g, obtained for the AC with the highest specific surface area. Additionally, different activation times, levels of heating, and chemical reagents were used to compare and determine the optimal parameters for obtaining high surface area of the activated carbon.

• 한국환경과학회지
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• 제10권5호
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• pp.373-380
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• 2001

In recent years, the demand of activated carbon has been increasing steadily because of the environmental problems. Among them waste and water treatment and removal of poisonous gas were invorved. Therefore, in this study, activated carbon was made from the waste chinese cabbage and measured the iodine adsorption ability, carbonization yield, and activation yield of the produced activated carbon. The result showed that the carbonization yield was decreased when carbonization temperature was increaed and that the optimal carbonization temperature was $600{\circ}C$. The optimal concentration of NaOH for removing ash in the raw sample was 1~2N. The range of iodine adsorption number of activated carbon using chinese cabbage at $600{\circ}C$. carbonization was 610.82mg/g to 1019.58mg/g. The activation result of carbonization sample showed that the optimal activation condition was the carbonization at $400\circ}C$ and the activation at$700{\circ}C$. So the production of activated carbon using chinese cabbage was possible in the aspect of reuse of resource and decrease of environmental pollution compared to the commercial activated carbon.

• 한국세라믹학회지
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• 제42권7호
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• pp.469-474
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• 2005

Activated Carbon Fibers (ACFs) are widely used as adsorbents in technologies related to pollution abatement due to their highly porous structure and large adsorption capacity. The porous structure and surface area of ACFs depends strongly on both the activation processes arid the nature .of the precursors. The chemical activation with hydroxides has recently been, of great interest as it permits the preparation of activated carbon fibers with highly developed porosity. In this work, OXI-PAN fiber used as precursor for the preparation of activated carbon fibers by chemical activation with KOH and NaOH. The affects of several activation conditions on the surface properties, pore size distribution and adsorption capacity of Ag ion and Iodine ion on ACFs studied.

• Advances in materials Research
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• 제4권3호
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• pp.133-144
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• 2015

The aim of this investigation is to prepare geopolymer resin by alkali activation of ceramic waste (AACW) with different sodium hydroxide (NaOH) and liquid sodium silicate (LSS) concentrations. In order to prepare geopolymer cement, AACW was replaced by 10 and 30 % by weight (wt.,) of concrete waste (CoW) as well as 10 and 30 wt., % ground granulated blast-furnace slag (GGBFS). The results showed that, the compressive strength of AACW increases with the increase of activator content up to 15:15 wt., % NaOH: LSS. All AACW hardened specimens activated by 3:3 (MC6), 6:6 (MC12), 12:12 (MC24) and 15:15 wt., % (MC30) NaOH: LSS destroyed when cured in water for 24h. The MC18 mix showed higher resistivity to water curing. The results also showed that, the replacement of AACW containing 9:9 wt., % NaOH: LSS (MC18) by 10 (MCCo10) and 30 (MCCo30) wt., % CoWdecreased the compressive strength at all ages of curing. In contrast, the MCCo10 mix showed the lower chemically combined water content compared to MC18 mix. The MCCo30 mix showed the higher chemically combined water content compared to MC18 and MCCo10 mixes. The compressive strength and chemically combined water of all AACWmixes containing GGBFS (MCS10 and MCS30) were higher than those of AACWwith no GGBFS (MC18). As the amount of GGBFS content increases the chemically combined water increases. The x-ray diffraction (XRD) proved that as the amount of CoWcontent increases, the degree of crystallinity increases. Conversely, the replacement of AACW by GGBFS leads to increase the amorphiticity character. The infrared spectroscopy (FTIR) confirms the higher reactivity of GGBFS compared to CoW as a result of successive hydration products formation, enhancing the compaction of microstructure as observed in scanning electron microscopy (SEM).

• Carbon letters
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• 제15권1호
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• pp.57-66
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• 2014

Three activated carbons (ACs) were prepared using NaOH (N) as an activating agent. Hydrofluoric acid pre-leached rice husk was used as a precursor. After leaching, the precursor was washed with distilled water, dried, crushed, and then sieved; a size fraction of 0.3-0.5 mm was selected for carbonization in the absence of air at $600^{\circ}C$. The carbonization product (LC) was mixed with NaOH at ratios of 1:2, 1:3, and 1:4 (wt of LC: wt of NaOH) and the produced ACs after activation at $800^{\circ}C$ were designated NLC21, NLC31, and NLC41, respectively. Surface and textural properties were determined using nitrogen adsorption at $-196^{\circ}C$, scanning electron microscopy images, thermogravimetric analysis, and Fourier transform infrared spectra. These ACs were used as adsorbents for lead(II) from aqueous solutions. The effects of the textural properties and the chemistry of the carbon surfaces were investigated and the impact of the operation conditions on the capacity for lead(II) sorption was also considered. Modification of NLC41 with $H_2O_2$ and $HNO_3$ gave two other adsorbents, $H_{NLC41}$ and $N_{NLC41}$ respectively. These two new samples exhibited the highest removal capacities for lead(II), i.e.117.5 and 128.2 mg/g, respectively. The adsorption data fitted the Langmuir isotherm and the kinetic adsorption followed pseudo-second order kinetics. The thermodynamic parameters have been determined and they indicated a spontaneous endothermic process.

• 대한물리의학회지
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• 제7권3호
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• pp.275-282
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• 2012

Purpose : Bridge exercise has been commonly used in clinical rehabilitation settings to improve trunk control, and hip adductor muscles were a related muscle that may affect trunk muscle activation. The aim of this study was to investigate whether the co-contraction of hip adductor muscles may affect trunk muscle activation during bridge exercises. Methods : Thirty-eight healthy young subjects (19 men and 19 women) performed bridge exercises (with and without hip adduction movement). Surface electromyography (EMG) data were collected from the dominant-side internal oblique (IO), rectus abdominis (RA), multifidus (MF) and erect spine (ES) during bridge exercises to compare trunk muscles activation patterns. Result : The EMG activities of IO and RA appeared to be significantly higher during bridge exercise with hip adductor co-contraction than during bridge exercise alone (p<.01), but there were no significant differences in those of MF and ES. Furthermore, there were significant differences in the IO:RA EMG ratio during bridge exercise with hip adductor co-contraction (p<.05). Conclusion : These findings suggest that integration of hip adduction during bridge exercise may be beneficial in increasing deep muscles' activity for trunk stabilization.