• 한국산학기술학회논문지
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• 제10권5호
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• pp.955-961
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• 2009

현재 소형 휴대용 배터리의 용량 증가에 따라 배터리 부피가 커지는 문제를 가지고 있다. 이러한 문제를 해결하기 위해 직접 메탄올 연료전지가 대안으로 떠오르고 있다. 본 논문에서는 직접 메탄올 연료전지를 상온 상태에서 자연 대류 방식으로 공기를 공급하고, 메탄올의 농도와 유량의 변화에 대한 특성을 분석하였다. 분석 결과 저 농도의 메탄올에서는 수소 이온의 확산 속도 지연에 따른 분극현상이 발생하였고, 메탄올의 공급량이 높을수록 전지 Cell의 냉각 효과가 발생하여 출력이 감소한다.

• The Korean Journal of Physiology
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• 제9권1호
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• pp.69-76
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• 1975

Cardiac performances were analyzed in intact turtle heart(Amyda japonica), perfusing with turtle Ringer-Locke's solution containing various hydrogen ion concentration, at several levels of arterial and venous pressure. 1. Ventricular work increased when venous pressure, or venous filling pressure increased, and also increased when arterial pressure increased. 2. The higher the arterial pressure, the lower the cardiac to output, for arterial pressure is the resistance to the ventricular blood flow. On the other hand, in specific arterial pressure, cardiac output was proportional to the venous filling pressure. 3. Heart rates did not change significantly during the perfusion with Ringel· solution of various pH. 4. In the heart Perfused with Ringer solution of various pH, ventricular work was the highest at PH 7.6 (at 6 $cmH_2O$ arterial pressure and 8 $cmH_2O$ venous pressure, the ventricular work was 63.09m$\cdot$cm). However, within the range of pH $7.1{\sim}7.6$, there were no significant changes in cardiac output and ventricular work. Below the level of pH 7.0, ventricular work decreased to less than 56% of maximium value (at $6cmH_2O$ arterial pressure and $8cmH_2O$ venous Pressure, ventricular work was 36.0$gm{\cdot}$ at pH 7.0). At pH 7.7 ventricular work decreased to less than 48% of maximum value (ventricular work: 30.0 $gm{\cdot}$). The nature of the cardiac performance at the various arterial and venous pressures was similar to that of normal heart. 5. Turtle heart seemed to be relatively insensitive to acid-base disturbances. The mechanism of negative inotropic effect of hydrogen ion was discussed.

• 대한화학회지
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• 제30권1호
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• pp.57-62
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• 1986

HCr$O_4^-$에 의한 $[Mo_3O_4(C_2O_4)_3(H_2O)_3]^{2-}$의 산화는 몰리브덴(IV)화합물, $[Mo_2O_5(C_2O_4)_2(H_2O)_2]^{2-}$를 생성한다. HCr$O_4^-$와 $[Mo_3O_4(C_2O_4)_3(H_2O)_3]^{2-}$의 반응에 대한 화학양론은 $2Mo_3^{IV} + 4Cr^{VI} {\to} 3Mo_2^{VI} + 4Cr^{III}$와 같다. 관찰된 속도상수는 수소이온농도에 의존한다.$Cr^{VI}$는 $Cr^V$와 $Cr^{IV}$를 거쳐서 $Cr^{III}$로 일전자씩 연속적으로 변화한다. 상세한 메카니즘이 논의된다.

• 신재생에너지
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• 제18권4호
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• pp.1-11
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• 2022

Landfill gas (LFG) generation characteristics in a construction waste landfill zone (block E) and mixed landfill zone (block A) were analyzed. During the period from October 2018 to April 2022, a total of 936×10³ and 1,001×10³ tons of waste were disposed in block E and block A, respectively. Out of this, 27.1% and 55.6% were biodegradable waste in block E and block A, respectively. The landfill masses of the two blocks were converted to be comparable. Then, the biodegradable waste and organic carbon were estimated by element analysis, biodegradable carbon by biochemical methane potential experiment (DC), and sulfate ion by acid decomposition. Results showed that biodegradable waste, organic carbon, biodegradable carbon, and sulfate ions in block A were 2.1, 1.6, 5.2, and 0.4 times greater than those in block E, respectively. The amount of LFG generated by block A was 4.8 times greater than that by block E. The average concentrations of methane (CH₄) were 60.8% and 60.9% in block E and block A, respectively, which were unrelated to the nature of disposed waste. The average concentrations of hydrogen sulfide (H₂S) were significantly high in block E (4,489 ppm) and block A (8,478 ppm). As the DC/SO₄^2- of block E and block A were 0.35 and 4.56, respectively, increase in DC/SO₄^2- caused increase in not only the total amount but also the concentration of H₂S generated.

• 대한화학회지
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• 제14권3호
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• pp.213-219
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• 1970

In the presence of hydrogen peroxide, the effects of temperature and pH to the catalytic reaction velocity of cupric -thiocyanate and the quantities of reduction products adsorbed on the D.M.E. have been studied by polarographic method. According to these experiments, the following empirical equation has been derived for the relation among temperature $T_i$, concentration of hydrogen ion $pH_i$ and adsorbed cuprous-thiocyanate in moles/$cm^2Z_{ij}$, and rate constant log$K_{ij}$ $$log\;K_{ij}=\frac{1}{T_i}\{A(pH_j)+B\}+C(pH_j)+D$$ $$Z_{ij}=\frac{1}{T_i}\{{\alpha}(pH_j)^{\frac{1}{2}}+{\beta}\}+{\gamma}(pH_j)^{\frac{1}{2}}+{\delta}$$ where, A,B,C,D and {$\alpha},{\beta},{\gamma},{\delta}$ are constants. The Calculated values by both equations are well agreed with empirical values within 8% in the error.

• 대한수의학회지
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• 제61권4호
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• pp.40.1-40.6
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• 2021

Acid-base disorder is a common problem in veterinary emergency and critical care. Traditional methods, as well as the Stewart method based on strong ion difference concepts and the Fencl-Stewart method, can be used to analyze the underlying causes. On the other hand, there are insufficient comparative study data on these methods in cats. From 2018 to 2020, 327 acid-base analysis data were collected from 69 sick and 18 healthy cats. The three most well-known methods (traditional method, Stewart method, and Fencl-Stewart method) were used to analyze the acid-base status. The frequency of acid-base imbalances and the degree of variation according to the disease were also evaluated. In the traditional acid-base analysis, 5/69 (7.2%) cats showed a normal acid-base status, and 23.2% and 40.6% of the simple and mixed disorders, respectively. The Fencl-Stewart method showed changes in both the acidotic and alkalotic processes in 64/69 (92.8%), whereas all cats showed an abnormal status in the Fencl-Stewart method (semiquantitative approach). The frequencies of the different acid-base imbalances were identified according to the analysis method. These findings can assist in analyzing the underlying causes of acid-base imbalance and developing the appropriate treatment.

• 한국응용과학기술학회지
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• 제7권1호
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• pp.93-105
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• 1990

Semicarbazone formation of nine monosubstituted benzaldehydes was studied kinetically in 20% methanol buffer solution at 15, 25, 35, and $45^{circ}C$. The rate of p-nitrobenzaldehyde semicarbazone formation is 2.7 times as fast as that of benzaldehyde, while p-hvdroxybenzaldehyde is 3.6 times as slow as that of benzaldehyde. Activation energies for p-chlorobenzaldehyde, benzaldehyde, p-methylbenzaldehyde, p-methoxybenzaldshyde, p-hydroxybenzaldehyde, and p-dimethylaminobenzaldehyde semicarbazone formation are calculated as 5.80, 6.19, 6.57, 7.06, 8.03, and 6.46 kcal/mol respectively. It is concluded from the effect of ionic strength that the reaction is affected by not ions but neutral molecules involving hydrogen bonding between oxygen atom of carbonyl group and hydrogen atom of acid-catalyst, and concerted attack of the necleophilic reagent, free base on carbonyl compound. Also, the effect of solvent composition is small in 20% and 50% methanol (and ethanol) aqueous solutions. The ${\rho}-{\sigma}$ plots for the rates of semicarbazone formation at pH 7.1 show a linear ${\rho}-{\sigma}$ relationship (${\rho}=0.14l$, in contrast to that at pH 2.75 and pH 5.4 corresponding to ${\rho}-{\sigma}$ correlations reparted by Jencks. The rate of semicarbazone formation at pH 5.4 show a relationship which is convex upward, resulting in a break in the curve but at pH 2.75, slight difference from a linear relationship. As a result of studying citric acid catalysis, second-order rate constants increase linearly with citric acid concentration and show a 2 times increase as the catalyst concentration is varied from 0.025 to 0.1 mol/1 at pH 2,9, but slight increase at pH 5.3. The rate-determining step is addition below pH 5 but is dehydration between pH 5 and 7. Conclusively, the rate-determining step of the reaction changes from dehydration to addition in respect to hydrogen ion activity near pH 5. The ortho: para rate ratio of the hydroxybenzaldehydes for semicarbazone formation is about 17 at $15^{\circ}C$. It is concluded that the results constitute strong evidence in favor of greater stabilization of p- than o-hydroxybenzaldehyde by substituent which donate electrons by resonance and is due to hydrogen bonding between the carbon-bound hydrogen of the-CHO group and the oxygen atom of the substituent.

• 분석과학
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• 제5권4호
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• pp.401-408
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• 1992

산화칼슘과 산화철을 0.6:1.4, 0.8:1.2, 1.0:1.0 몰비로 혼합하여 만든 디스크 형태의 시편들을 $1400^{\circ}C$ 산소 분위기와 수소 분위기하에서 각각 소결하였다. 수소 분위기하에서 만든 calcium ferrite 막전극이 산소 분위기하에서 만든 calcium ferrite 막전극 보다 더 우수한 감응전위와 감응농도범위를 나타냈다. 수소 분위기하에서 만든 calcium ferrite ($CaO:Fe_2O_3=0.6:1.4$ 몰비) 막전극은 $Ca^{2+}$, $Ba^{2+}$, $Mg^{2+}$, $Zn^{2+}$와 같은 2가 금속 양이온과 $I^-$, $Br^-$와 같은 할로겐 음이온에 대하여 Nernstian 기울기에 근접한 높은 감응전위를 나타내었다.

• 공업화학
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• 제10권2호
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• pp.218-224
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• 1999

원자로 정지시 혼상 탈염기의 최적 운전방법을 제안할 목적으로 산성-산화성 분위기에서 저농도의 Ni, Co 및 Ag 이온이 함유된 모의 냉각재 용액의 연속식 이온교환특성을 연구하였다. 금속 이온의 제거 용량에 미치는 양이온 교환수지 형태의 효과로서 $H^+$형 수지의 성능은 $Li^+$형 수지의 성능보다 약 6% 정도 높은 것으로 나타났다. 혼합층 이온교환 방법인 양이온과 음이온 수지의 혼합은 비혼합시와 비교하여 금속 이온들의 제거 용량에는 영향을 미치지 않았으나 금속 이온들의 파과곡선의 기울기를 매우 조금 증가시켰다. 냉각재의 산성-산화성 분위기와 관계된 영향으로서 붕산의 첨가는 금속 이온들의 파과곡선의 기울기를 매우 작게 감소시킨 반면, 과산화수소의 첨가는 금속이온들의 제거 용량을 약간 감소시켰다.

• 한국의류학회지
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• 제18권5호
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• pp.661-673
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• 1994

We have gathered a fatty acid to recycle the waste oil of food manufacturing process, and then made a soap from the waste oil by alkali saponification. Effects of the washing elements such as the concentration of the soap, temperature and time were evaluated to find out the optimum washing conditions, and results are as follows. 1. We could find soaps made from the soybean oil (A), corn oil (B), rape seed salad oil (C), cotton seed oil (D) and a soap consisting of the each oil 25% respectively (I) had the lowest surface tension at the concentration of 0.225% -0.25%. Compared with the single fatty-acid soap, the multi-component soap I showed the lower surface tension at the cmc. 2. All the samples of A-I showed the lowest contact angle for the solid material at the concentration of 0.25%. The multi-component soap of I showed higher contact angle than the single.component soaps of A, B, C and D. 3. The soap G, made from the waste oil, show lower surface tension than 5, made from the complex raw fats of the eatable fatty oil acid and H, commercial soap. 4. The washing efficiency depends on the washing time. Especially the 25-minute was found to be the optimum washing time. 5. The highest washing efficiency was found at the 0.25% cont. reagardless of the washing temperature. At 0.15% concentration level the washing efficiency reduces as washing tem- perature increases. At 0.3% concentration level the highest washing efficiency was found between $50^{\circ}$-$60^{\circ}$. 6. The soap made from the waste oil showed the highest washing efficiency in terms of concentration, temperature, and time. 7. The soap made from the waste oil showed the similiar concentration of hydrogen ion to the synthetic detergent. 8. The hand value of the fabric washed by the soap made from the waste oil was a little lower value than those washed by the synthetic detergent.