• Journal of the Korean Chemical Society
• /
• v.14 no.2
• /
• pp.141-145
• /
• 1970

The reduction of Mo-thiocyanate (V) complex on dropping mercury electrode has been studied at ionic strength 0.6 with pH less than 2.3. D-C polarogram obtained from acidic solutions are reversible, diffusion controlled current. The electrode reaction of Mo-thiocyanate(V) may be represented as follows. $MoO(SCN)_3\;+\;2H^+\;+\;2e\;{\to}\;Mo(SCN)_2{^+}\;+\;H_2O\;+\;SCN^-$From this reaction, the half wave potential assumed to be $E_{1/2}\;=\;E_0'\;-\;0.059\;pH\;-\;0.03\;log{\;frac{[Mo(SCN)_2{^+}][SCN^-]}{[MoO(SCN)_3]}}$Considering the dissociation of this complex, however, it was estimated that the electrode reaction may be written by. $MoO^{+3}\;+\;3SCN^-\;+\;2H^+\;+\;2e\;{\to}\;Mo(SCN)_2{^+}\;+\;SCN^-\;+\;H_2O$.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.22 no.1
• /
• pp.15-21
• /
• 2012

This paper deals with an experimental study on the reaction of muscles by functional electrical stimulation(FES) with the design and fabrication of an ankle reaction apparatus. The ankle reaction apparatus consists of a circuit part and a kinematic part, and it monitors reaction time for a particular angle of joint rotation according to FES. The experimental results showed that the change of the ankle rotation angle was linearly proportional to the change of the magnitude of FES. It also showed that the muscle's reaction time was constant no matter how large the magnitude of the stimulus. The results of this paper can be applied to develop an active-type walking-assistance robot.

• Journal of the Korean Society of Combustion
• /
• v.16 no.3
• /
• pp.33-40
• /
• 2011

Combustion experiments were conducted at three different fuels ($CH_4$, $C_2H_4$ and $C_3H_8$) to investigate the effects of combustor pressure (30 ~ -30 kPa) on combustion charateristics and reaction zone structure. Regardless of the fuels, emission index of CO (EICO) increased with decreasing combustor pressure, and EICO of $C_2H_4$ was mostly affected by changing combustor pressure at subatmospheric pressure. In order to observe reaction zone, $OH^*$, $CH^*$ and ${C_2}^*$ chemiluminescence intensity were measured. The sequence of the chemiluminescence intensity peak position was affected by chemical characteristics of fuels rather than changing combustor pressure. The emission zone thickness of $C_2H_4$ and $C_3H_8$, defined by the full width at half maximum (FWHM) of $CH^*$ intensity profile, were increased with decreasing combustor pressure. however, the thickness of $C_2H_4$ exhibited the opposite tendency due to the characteristics of the fuel as the bond structure.

• Resources Recycling
• /
• v.15 no.3 s.71
• /
• pp.58-65
• /
• 2006

The applicability of the waste pulp which produced in the paper recycling process as an adsorbent for the treatment of $Ni^{2+}$ ion in wastewater has been investigated taking the initial concentration of adsorbate, temperature, the amount of adsorbent, and solution pH as the experimental variables. In addition, the effect of the concentration of coexisting solute and pre-treatment of adsorbent on the adsorbability of $Ni^{2+}$ ion were also examined. The electrokinetic potential of waste pulp was observed to be positive below pH 7.8 and negative above this pH. The adsorption reaction of $Ni^{2+}$ ion reached its equilibrium within 4 hours after the reaction was initiated and the adsorbed amount of adsorbate was found to increase with its initial concentration. The adsorbability of $Ni^{2+}$ was raised with temperature so that its adsorption reaction was considered to be exothermic, which was substantiated by thermodynamic calculation. Also, the adsorbed amount of $Ni^{2+}$ was raised with the amount of waste pulp and with pH in the range of pH $3{\sim}6$. This behavior of the adsorption of $Ni^{2+}$ according to the solution pH was well agreed with the electrokinetic characteristics of waste pulp in solution. The amount of coexisting solute was observed to reversely affect on the $Ni^{2+}$ adsorption onto waste pulp under the experimental conditions. With regard to the pre-treatment of adsorbent with NaOH, the adsorbability of $Ni^{2+}$ was increased with the concentration of NaOH to a certain extent. However, it was found to decrease contrarily when the concentration of NaOH became too high.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.29 no.9 s.240
• /
• pp.979-987
• /
• 2005

Numerical simulations were performed at atmospheric pressure in order to understand the effect of additives on flame speed, flame temperature, radical concentrations, $NO_x$ formation, and heat flux in freely propagating $CH_4-Air$ flames. The additives were both carbon dioxide and hydrogen chloride which had a combination of physical and chemical behavior on hydrocarbon flame. In the flame established with the same mole of methane and additive, hydrogen chloride significantly contributed toward the reduction of flame speed, flame temperature, $NO_x$ formation and heat flux by the chemical effect, whereas carbon dioxide mainly did so by the physical effect. The impact of hydrogen chloride on the decrease of the radical concentration was about $1.4\~3.0$ times as large as that of carbon dioxide. Hydrogen chloride had higher effect on the reduction of $EI_{NO}$ than carbon dioxide because of the chemical effect of hydrogen chloride. The reaction, $OH+HCl{\rightarrow}Cl+H_2O$, played an important role in the heat flux from flames added by hydrogen chloride instead of the reaction, $OH+H_2{\rightarrow}H+H_2O$ which was an important reaction in hydrocarbon flames.

• Bulletin of the Korean Chemical Society
• /
• v.26 no.4
• /
• pp.609-613
• /
• 2005

The fragmentation patterns and ion-molecule reactions of two alkyn alcohols, 2-propyn-1-ol (HC≡$CCH_2$OH) and 2-methyl-3-butyn-2-ol (HC≡CC($CH_3)_2$OH), were investigated using Fourier transform mass spectrometry (FTMS). The most abundant fragment ions formed from the molecular ions were [M-H]$^+$ for 2-propyn-1-ol and [M-$CH_3]^+$ for 2-methyl-3-butyn-2-ol. The dehydrated ion, [M-$H_2O]^+$ was formed only from 2-propyn-1-ol in which $\alpha$ -hydrogen atoms were available for $\alpha,\;\alpha$ -elimination reaction. The protonated molecules were dissociated into [M+H-$H_2O]^+$ and [M+H-$C_2H_2]^+$ through dehydration and deacetylenylation processes. The formations of [M+H-$H_2O]^+$ and [M+H-$C_2H_2]^+$ from 2-methyl-3-butyn-2-ol were more favorable than those from 2-propyn-1-ol due to stabilization by two methyl groups at $\alpha$ -carbon. Ion-neutral complexes formed at long ion trapping time gave dehydrated and/or deacetylenylated ion products by further dissociation.

• KSBB Journal
• /
• v.9 no.3
• /
• pp.312-318
• /
• 1994

The esterification of Ac-Tyr-OH was carried out in one-phase system containing ethanol by ${\alpha}$-chymotrypsin. The results of the esterification reaction are as follows. Chitin-${\alpha}$-chymotrypsin complex was found to be an effective catalyst for the esterlfication of Ac-Tyr-OH in ethanol organic solvent. The optimal conditions for the esterification were chitn/${\alpha}$-chymotrypsin ratio, 20(w/w); reaction temp., $35^{\circ}C$; reaction pH, 8.0; reaction time, 24 hrs. Also, addition of chitin in water/water-miscible organic solvent was effective for the stability of the enzyme. The esterification yield, Km and Vmax under optimal conditions were 93%, 3.093mM and 1.088mM/mg/hr, respectively.

• Bulletin of the Korean Chemical Society
• /
• v.23 no.1
• /
• pp.35-40
• /
• 2002

Photoreaction of guest organic anions in layered organic-inorganic hybrid materials was investigated. The layered hybrids were synthesized by an anion-exchange reaction of $[LiAl_2(OH)_6]Cl{\cdot}yH_2O$ layered double hydroxide with aqueous (Z,Z)- and (E,E)-muconates under inert atmospheric condition, to give new organicinorganic hybrids of $[LiAl_2(OH)_6]_2[(Z,Z)-C_6H_4O_4]{\cdot}zH_2O$ and $[LiAl_2(OH)_6]_2[(E,E)-C_6H_4O_4]{\cdot}H_2O$, respectively. The basal spacings calculated by XRPD of intercalates indicate that muconate anions have almost vertical arrangements against the host $[LiAl_2(OH)_6]^+$ lattices in the interlayer of organic-inorganic hybrid materials. When UV light was irradiated on the suspension of $[LiAl_2(OH)_6]_2[(Z,Z)-C_6H_4O_4]{\cdot}zH_2O$, the (Z,Z)-muconate anions of the gallery space of hybrids were polymerized in the aqueous media while it was isomerized into more stable (E,E)-muconate in the methanollic suspension in the presence of catalytic amount of molecular iodine. All the products were characterized using elemental analysis, TGA, XRPD, FT-IR, $^1H$ NMR and $^{13}C$ CP-MAS NMR.

• Preventive Nutrition and Food Science
• /
• v.15 no.4
• /
• pp.309-315
• /
• 2010

A grilled-type shrimp flavor was developed through the Maillard reaction to reduce or mask fish odor or off-flavor in seafood. Model systems were created by using enzymatic hydrolysate of shrimp and adding precursors to increase flavor quality and stability. Amino acid precursors such as cysteine and methionine, sugar precursors such as glucose, xylose, ribose, and sucrose, and one particular compound of glucosamine were tried and their flavor qualities were tested by sensory evaluation. Also, the optimum reaction condition was investigated using the pH values of pH 5, 6, 7, and 8 with reaction times of 1 hr, 2 hr and 3 hr after the best precursors were determined. The best condition of the precursors for grilled-type shrimp flavor was the mixtures of methionine, threonine, xylose, and glucosamine. The optimum reaction condition was at pH 8.0 and 2 hr reaction time.

• Journal of Korea Foundry Society
• /
• v.28 no.6
• /
• pp.282-287
• /
• 2008

The effect of CaO mold on the formation of reaction layer was investigated. CaO mold was prepared by mixing of Colloidal silica($NALCO^{(R)}$ 1130) and an $ZrO_2$, CaO at room temperature. The dried at $20{\pm}3^{\circ}C$, 75% humidity for 12hrs. Sample was prepared from the Cp-Ti(grade-2) and melted by high frequence induction melting system in the vacuum condition. The react ion layer of Ti was confirmed by optical microscopy, microhardness(Hv) and X-ray diffraction. Thickness of reaction layer using the CaO stabilized ZrO2 was thinner than the CaO added ZrO2. And thickness of reaction layer were decreased with decreasing pH of slurry. CaO addition in the slurry could not controlled reaction between molten Ti and investment mold. On the other hand, the CaO chemical bonded ZrO2 by stabilization treatment could controlled reaction between molten Ti and investment mold.