• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2017년도 제48회 춘계학술대회논문집
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• pp.128-130
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• 2017

수중추진을 위한 고체추진제로 알루미늄 분말의 수반응성을 높이기 위하여 $NaBH_4$를 첨가하였다. 알루미늄 분말은 $NaBH_4$의 첨가량에 따라 다른 연소특성을 보였다. $NaBH_4$를 첨가하였을 때 끓는점보다 훨씬 낮은 온도에서도 물과 반응하여 연소되었다. 본 연구에서 $NaBH_4$는 Al 분말과 증기 반응을 촉진시키는 효과적인 첨가제임을 확인하였다.

• Nuclear Engineering and Technology
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• 제56권3호
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• pp.1022-1028
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• 2024

A neutronics study of a supercritical CO₂-cooled fast reactor core for nuclear propulsion has been performed in this work. The thermal power of the reactor core is 30 MWth and a ceramic UO₂ fuel can be used to achieve a 20-year lifetime without refueling. In order to make a compact core with inherent safety features, the drum-type reactivity control system and folding-type shutdown system are adopted. In addition, we suggest a cold shutdown system using gadolinium as a spectral shift absorber (SSA) against flooding. Although there is a penalty of U-235 enrichment for the core embedded with the cold shutdown system, it effectively mitigates the increment of reactivity at the flooding of seawater. In this study, the neutronics analyses have been performed by using the continuous energy Monte Carlo Serpent 2 code with the evaluated nuclear data file ENDF/B-VII.1 Library. The supercritical CO₂-cooled fast reactor core is characterized in view of important safety parameters such as the reactivity worth of reactivity control systems, fuel temperature coefficient (FTC), coolant temperature coefficient (CTC), and coolant temperature-density coefficient (CTDC). We can say that the suggested core has inherent safety features and enough flexibility for load-following operation.

• 한국전기전자재료학회논문지
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• 제32권3호
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• pp.223-228
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• 2019

We fabricated a printed Ag:CNT film as a liquid sensor for the detection of HNS (hazardous and noxious substances) in seawater. The paste required for printing was prepared using Ag powder, MWCNTs (multi-walled carbon nanotubes), and an organic binder. The heat treatment process for binder removal was optimized. In order to confirm that the sensor was operational, the resistance change characteristics in brine (3.5%) and methanol (99.8%) were assessed at $20^{\circ}C$. EDL (electrical double layer) formation and redox reactivity were confirmed as the most important reactions affect each electrical property of sensor in brine and methanol. From these results, it was determined that printed Ag:CNT film can be applied as a sensor to detect HNS in seawater.

• 한국건설순환자원학회논문집
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• 제9권4호
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• pp.578-584
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• 2021

본 연구에서는 매립회의 유효 활용을 위해 플라이애시(FA)와 매립회(PA) 4종의 수화반응 및 강도발현 특성을 비교 분석하였다. 해수 이동방식에 의해 염소함량 높은 PA는 시멘트 수화반응 촉진으로 FA와 비교하여 응결시간이 촉진되고, 누적 발열량이 증가하였으며, 초기 강도발현이 향상되었다. 그러나 재령 7일 이후 초기 수화물의 급격한 생성으로 활성도 지수 증가율은 감소하였다. 다량의 미연탄소 등 불순물을 함유한 PA는 낮은 수화 반응성으로 응결시간이 지연되고, 전 재령에서 강도가 저하되었다. 담수 이동방식에 의해 염소함량 낮고, 비정질량이 높은 PA는 FA와 유사한 수화반응 및 강도발현 특성을 나타냈다. 열중량 분석결과로 FA와 비슷한 수준의 Ca(OH)₂ 소비량과 포졸란 반응성을 가진 것을 확인하였다. 결과적으로 매립회의 활용성 높이기 위해서는 담수 이동방식의 적용 확대와 강열감량의 관리가 필요할 것으로 분석되었다.

• Bulletin of the Korean Chemical Society
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• 제28권3호
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• pp.432-438
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• 2007

Environmentally important phthalic esters have been analyzed by GC-MS in terms of individual phthalic esters or total phthalic esters directly or after derivatization. Derivatization improves the chromatographic characteristics of the highly polar phthalic esters. This study focused on the GC-MS determination of the total phthalic esters and the individual phthalic esters simultaneously. The phthalic esters were hydrolyzed to phthalate and corresponding alcohols in 1 M NaOH solution at 90 oC for 30 min followed by extraction with ethyl acetate after acidifcation. The phthalic acid and alcohols were simultaneously silyl derivatized using bis(trimethylsilyl)trifluoroacetamide (BSTFA) to their corresponding silyl ester and ethers in the mixture of 60% acetone and 40% ethyl acetate at room temperature within 30 min. Because of the high reactivity of BSTFA with the phthalic acid and alcohols effective silyl derivatization was possible simultaneously. GC-MS analysis of the silyl derivatives of phthalic acid and alcohols was performed. The total phthalic ester content was estimated from the analytical result of phthalic silyl ester, while the individual phthalic ester was quantified from the analytical results of alcoholic silyl ethers. This technique was applied to spiked tab water and real seawater samples from the Lake Shihwa in Korea. The results were checked against the results from the direct GC-MS analysis of the phthalic esters and reasonable recoveries with high sensitivity were achieved. The recoveries were higher than 75% with low relative standard deviation (below 10%).