• Transactions of the Korean Society of Automotive Engineers
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• v.14 no.2
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• pp.84-91
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• 2006

A heavy duty hydrogen-natural gas fueled engine can obtain stable operation at ultra lean conditions and reduce emissions extremely. Reduction of $CO_2$ in its engine is one of the most benefit. In this study, rate of hydrogen addition($R_{dH2}$) and compression ratio($\varepsilon$) were investigated including performance of this engine. As results, it was found that phenomenon of pressure oscillation when increasing $R_{dH2}$ and $\varepsilon$, it means occurring knock. It consider that pressure oscillation was increased due to fast burning speed of hydrogen. Even if same compression ratio, pressure oscillation was remarkable increased according to increasing $R_{dH2}$. Therefore, limit compression ratio of knock occurring was reduced by increasing $R_{dH2}$.

• Korean Journal of Microbiology
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• v.24 no.2
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• pp.113-118
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• 1986

Optimum temperature and pH of glutamine synthetase activity (E.C. 3.6.1.2.) of R. sphaeroides D-230 was $35^{\circ}C$ and 6.8, respectively. The adenylated state of GS in R. sphaeroides D-230 was stabilized by addition of 0.2mg/ml of cethyltrimethylammoniumbromide. Valine, histidine, proline, isoleucine, and lysine were good nitrogen source for the growth of R. sphaeroides D-230. The growth of R. sphaeroides D-230 in $N_2,\;NaNO_3\;or\;NH_4Cl$ as sole nitrogen source was lower than in any otherculture conditions. GS activity was inhibited, more or less, by various amino acid. THe relative inhibition rate of the enzyme by added 7mM arginine, $NH_4Cl,\;N_2,\;and\;NaNO_3$ was 63.8%, 26.79%, 6.24%, and 10.64%, drespectively. THe hydrogen evolution of R. sphaeroides D-230 grown in N-limited media was inhibited by 0.1mM MSX, irreversible GS inhibitor. GS activity was completely inhibited by 1.0mM MSX but ammonia released maximally at the same concentration of MSX. Ammonia release by added MSX was increased up to 1.0mM MS, but decreased above 1.0mM MSX. It is probably due to inhibition of nitrogenase actixity by MSX. Nitrogenase activity was not inhibited at low concentration of MSX. These results suggests that the inhibition of nitrogenase activity by ammonia is mediated by products of ammonia assimilation rather than by ammonia itself.

• Transactions of the Korean hydrogen and new energy society
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• v.17 no.1
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• pp.31-38
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• 2006

There are two types of metal hydride electrodes as a negative electrode in a Ni-MH battery, $AB_2$ Zr-based Laves phases and $AB_5$ LM(La-rich mischmetal)-based alloys. The $AB_5$ alloy electrodes have characteristic properties such as a large discharge capacity per volume, easiness in activation, long cycle life and a low cost of alloy. However they have a relatively small discharge capacity per weight. The $AB_2$alloy electrodes have a much higher discharge capacity per weight than $AB_5$ alloy electrodes, however they have some disadvantages of poor activation behavior and cycle life. Therefore, in order to improve the discharge capacity of the $AB_5$ alloy electrode the Zr, Ti and V which are the alloying elements of the $AB_2$ alloys were added to the $LaNi_{3.6}Ai_{0.4}Co_{0.7}Mn_{0.3}$ alloy which was chosen as a $AB_5$ alloy with a high capacity. The addition of Zr, Ti and V to $LaNi_{3.6}Ai_{0.4}Co_{0.7}Mn_{0.3}$ alloy improved the activation to be completed in two cycles. The discharge capacities of Zr 0.02, Ti 0.02 and V 0.1 alloys in $LaNi_{3.6}Ai_{0.4}Co_{0.7}Mn_{0.3}M_y$ (M = Zr, Ti, V) were respectively 346, 348 and 366 mAh/g alloy. The alloy electrodes, Zr 0.02, Ti 0.05 and V 0.1 in $LaNi_{3.6}Ai_{0.4}Co_{0.7}Mn_{0.3}M_y$ (M = Zr, Ti, V), have shown good cycle property after 200 cycles. The rate capability of the $LaNi_{3.6}Ai_{0.4}Co_{0.7}Mn_{0.3}M_y$ (M = Zr, Ti, V) alloy electrodes were very good until 0.6 C rate and the alloys, Zr 0.02, Ti 0.05 and V 0.1, have shown the best result as 92 % at 2.4 C rate. The charge retention property of the $LaNi_{3.6}Ai_{0.4}Co_{0.7}Mn_{0.3}M_y$ (M = Zr, Ti, V) alloys was not good and the alloys with M content from 0.02 to 0.05 showed better charge retention properties.