http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Kim, Chungman,Kim, Soohyun,Hong, Yang-Ki,Oh, Min-Wook,Jung, Myung-Hwa Elsevier 2017 JOURNAL OF ALLOYS AND COMPOUNDS Vol.690 No.-
<P><B>Abstract</B></P> <P>Single crystals of Mg<SUB>2−<I>x</I> </SUB>Mn<SUB> <I>x</I> </SUB>Si (<I>x</I> = 0, 0.1, 0.2, 0.3, and 0.4) were prepared using a vertical Bridgman method. The formation of desired materials was confirmed using single-crystal and powder X-ray diffraction. The thermoelectric and magnetic properties were investigated for various Mn contents in the temperature range between 2 and 300 K and in magnetic fields up to 70 kOe. For various <I>x</I> values, Mg<SUB>2−<I>x</I> </SUB>Mn<SUB> <I>x</I> </SUB>Si with <I>x</I> = 0.2 possesses the highest figure of merit. The experimental results revealed that the substitutional Mn atoms exhibit mixed valences of +3 (majority) and +2, giving rise to dramatic changes of carrier density and magnetic interaction. At the same time, the Seebeck coefficient and magnetic susceptibility show a sudden change at the same temperature. These results imply that the thermoelectric properties are correlated with the magnetic properties in the Mg<SUB>2−<I>x</I> </SUB>Mn<SUB> <I>x</I> </SUB>Si crystals.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Single crystals of Mg<SUB>2−x</SUB>Mn<SUB>x</SUB>Si were prepared by using a vertical Bridgman method. </LI> <LI> The thermoelectric performance was improved as doping Mn into Mg<SUB>2</SUB>Si. </LI> <LI> The magnetic properties were enhanced with Mn dopants. </LI> <LI> The thermoelectric and magnetic properties were strongly correlated in Mg<SUB>2−x</SUB>Mn<SUB>x</SUB>Si. </LI> </UL> </P>
Continuous performance of hydrogenotrophic methanogenic mixed cultures: Kinetic and SMP analysis
Kim, Mi-Sun,Moon, Chungman,Kang, Seoktae,Kim, Dong-Hoon Elsevier 2017 INTERNATIONAL JOURNAL OF HYDROGEN ENERGY - Vol.42 No.45
<P><B>Abstract</B></P> <P>To investigate the characteristics of hydrogenotrophic methanogenic (HM, 4H<SUB>2</SUB> + CO<SUB>2</SUB> → CH<SUB>4</SUB> + 2H<SUB>2</SUB>O) mixed cultures, continuous stirred-tank reactors (CSTRs) were operated at various H<SUB>2</SUB> loading rates (HLR, 2.8–14.0 m<SUP>3</SUP> H<SUB>2</SUB>/m<SUP>3</SUP>/d) and hydraulic retention times (HRTs, 5–30 d). The feeding gas was composed of H<SUB>2</SUB>/CO<SUB>2</SUB> (80:20 on volume basis), and HRT was controlled by the continuous pumping of a nutrient medium. At a fixed HLR of 4 kg COD/m<SUP>3</SUP>/d (1 kg COD = 1.4 m<SUP>3</SUP> H<SUB>2</SUB>), complete H<SUB>2</SUB> conversion to CH<SUB>4</SUB> (> 98% on a COD basis) was observed up to the HRT decrease to 6 d. However, at HRT 5 d, the H<SUB>2</SUB> conversion gradually decreased, reaching 30% within 30 d, and the H<SUB>2</SUB> content in the head space increased to 70%, which triggered the production of acetate with an increased concentration to 3 g COD/L. When the HLR was increased at a fixed HRT of 10 d, the maximum CH<SUB>4</SUB> production rate of 2.75 m<SUP>3</SUP> CH<SUB>4</SUB>/m<SUP>3</SUP>/d was achieved at 8 kg COD/m<SUP>3</SUP>/d. A kinetic analysis conducted using the Monod equation showed that HM cultures had a maximum specific growth rate of 0.18 d<SUP>−1</SUP> and a half-saturation coefficient of 1.73 g COD/L. Though, successful hydrogenotrophic CH<SUB>4</SUB> conversion was achieved, the broth contained soluble microbial products (SMPs) at a concentration of 80–250 mg/L, which exceeded the effluent regulation standard. Most of the organic matters in SMPs consisted of humic-like and fulvic-like organic matters with a low molecular weight (<1 kDa).</P> <P><B>Highlights</B></P> <P> <UL> <LI> Investigate the characteristics of hydrogenotrophic methanogens. </LI> <LI> CSTR operation at various H<SUB>2</SUB> loading rates and HRTs. </LI> <LI> Complete H<SUB>2</SUB> conversion to CH<SUB>4</SUB> up to the HRT decrease to 6 d. </LI> <LI> Maximum CH<SUB>4</SUB> production rate of 2.75 m<SUP>3</SUP> CH<SUB>4</SUB>/m<SUP>3</SUP>/d at 8 kg COD/m<SUP>3</SUP>/d. </LI> <LI> Maximum specific growth rate = 0.18 d<SUP>−1</SUP>, half-saturation coefficient = 1.73 g COD/L. </LI> </UL> </P>
저독성 접촉점화 추진제의 액주 충돌 실험에 대한 분석과 고찰
김충만(Chungman Kim),강홍재(Hongjae Kang),이경환(Kyounghwan Lee),이종광(Jongkwang Lee) 한국추진공학회 2023 한국추진공학회지 Vol.27 No.3
The research on low-toxic hypergolic propellants has increased since 2000. Many research groups have studied the evaluation methods of the ignition performance to develop low-toxic hypergolic propellants. Ignition performance could be evaluated through a drop test and a impinging jet test. The impinging jet test could simulate the actual rocket operation environment with simple experimental equipment. Combustion instability caused by the ignition methods could be observed in the impinging jet test. In this paper, We introduces various experimental methods for the impinging jet test and analyzes important results from previous studies.
Effect of the accuracy of pH control on hydrogen fermentation
Moon, Chungman,Jang, Sujin,Yun, Yeo-Myeong,Lee, Mo-Kwon,Kim, Dong-Hoon,Kang, Won-Seok,Kwak, Seung-Shin,Kim, Mi-Sun Elsevier 2015 Bioresource technology Vol.179 No.-
<P><B>Abstract</B></P> <P>pH, known as the most important parameter in H<SUB>2</SUB> fermentation, cannot be precisely controlled in a scaled-up fermenter as in a lab fermenter. In the preset work, to assess the effect of pH control accuracy on H<SUB>2</SUB> fermentation, the pH was controlled at 6.0±0.1, 6.0±0.3, 6.0±0.5, 6.0±0.7, and 6.0±0.9 during batch fermentation of food waste. Up to deviation of ±0.3, a high H<SUB>2</SUB> yield of 1.67–1.73molH<SUB>2</SUB>/mol hexose<SUB>added</SUB> was attained with producing butyrate as a major metabolite (>70% of total organic acids produced). A huge drop of H<SUB>2</SUB> production, however, was observed at deviation >±0.5 with lowered substrate utilization and increased production of lactate. Next generation sequencing results showed that <I>Clostridium</I> was found to be the dominant genus (76.4% of total number of sequences) at deviation of ±0.1, whereas the dominant genus was changed to lactic acid bacteria such as <I>Streptococcus</I> and <I>Lactobacillus</I> with increase of deviation value.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A significant effect of pH control accuracy on H<SUB>2</SUB> fermentation performance. </LI> <LI> High H<SUB>2</SUB> yield and substrate utilization at deviation of ±0.1 and ±0.3. </LI> <LI> Low H<SUB>2</SUB> production with lowered substrate utilization at deviation >±0.5. </LI> <LI> Lactic acid bacteria became dominant with increase of deviation value. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>