• Journal of Energy Engineering
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• v.1 no.1
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• pp.76-86
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• 1992

A three-dimensional model has been developed for pulverized coal combusters and gasifiers. Coal devolatilization, heterogeneous char oxidation, gas particle interchange, radiation, gas phase oxidation, primary and secondary stream mixing, and heat losses are considered. A finite difference method was used to solve the ordinary non-linear differential equations. The effects of primary and secondary stream flow ratio and coal particle size are investigated.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2015.11a
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• pp.156-156
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• 2015

도금 시뮬레이션의 목적은 실제 도금 상황에서의 전류밀도 및 도금두께 분포를 정확히 예측하여 최상의 품질과 최적의 공정조건을 확립하는데 있다. 제품에 부착된 도금 두께는 기하학적 배치에 의한 저항 (1차 전류밀도), 전기화학적 전하교환 반응에 의한 분극 (2차 전류밀도) 및 확산, 유동 등 도금물질의 공급에 의한 분극(3차 전류밀도)에 의해 결정이 된다. 현재까지 도금 시뮬레이션은 1차 전류밀도 예측에 대한 전자기학적 해석과 Butler-Volmer 식에 근거한 동력학적 전기화학 해석을 통해 2차 전류밀도 분포 해석만 이루어졌다. 즉, 도금 반응에 있어서 물질공급은 항상 일정하게 유지되는 것을 가정하고 해석을 하였다. 이는 3차 전류밀도 분포에 있어서 전극반응 계면에서의 유동에 의한 물질공급이 전기화학과는 다른 물리(physics) 영역이어서 이를 전기화학과 coupling 하는데 기술적으로 어렵기 때문이었다. 그러므로, 물질공급반응이 속도결정단계가 되는 고속도금이나 저농도 도금, gap, tranch, via hole, through hole 등의 도금의 경우에는 해석결과에 큰 오차를 야기하게 된다. 본 발표에서는 그동안 접근하지 못했던 전기도금 해석에 있어서 유동해석을 커플링하여 다중물리해석을 한 결과를 발표한다. 시편으로는 회전원판전극과 회전 헐셀을 이용하여 회전속도 (rpm)에 따른 전류밀도 및 도금두께 분포의 변화 거동을 예측하였다.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2002.11a
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• pp.391-392
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• 2002

대기 중에는 오염원으로부터 직접 배출된 1차 에어로졸과 광화학 반응 등에 의해 가스가 입자로 변환되어 생긴 2차 에어로졸이 존재한다. 2차 에어로졸의 생성과정을 규명하기 위하여 스모그 챔버 연구가 많이 수행되고 있다. 본 연구팀에서도 대기를 실내 스모그 챔버에 도입하여 광화학 반응에 의한 2차 에어로졸의 생성 및 성장과정을 규명하는 실험을 수행하고 있다 (박주연 등, 2002). (중략)

• Journal of the Korean Chemical Society
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• v.41 no.10
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• pp.535-540
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• 1997

Potassium carbonate reacts with silicon tetrachloride to form trichlorosilyloxy carbonylchloride which reacts subsequently with another molecule of silicon tetrachloride leading to phosgene eventually in chlorinated solvents. This in situ generated trichlorosilyloxy carbonylchloride or phosgene were found to be very effective for the chlorination of a wide variety of alcohols to the corresponding chlorides. Primary, secondary and benzylic alcohols were converted into corresponding chlorides when treated with silicon tetrachloride in the presence of potassium carbonate at room temperature.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.164.1-164.1
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• 2016

본 연구에서 지지체로 사용된 단결정 형태의 수산화인회석(Hydroxyapatite)은 칼슘과 인산염으로 구성된 무기물이다. 염기 조건 (10 M NaOH)에서 수열합성법 (Hydrothermal method)을 이용하여 단결정 형태의 수산화인회석을 합성하였다. 합성된 단결정 수산화인회석의 표면에 이온 교환 반응을 통하여 은 원자를 도입하였으며, 아르곤 및 수소 기류 (96% Ar, 4% $H_2$) 조건에서 가열하는 온도를 조절하는 것으로 은 나노 입자를 생성시켰다. 합성된 샘플은 XRD 패턴 및 TEM 이미지 분석을 통하여, 수산화인회석의 합성 및 은 나노 입자가 형성된 것을 확인하였다. 합성된 샘플을 유기 반응 촉매로 사용하여 여러 가지 알코올 (1차, 2차 알코올)의 산화 반응에 응용하였으며, UV-Visble light 영역에서의 메틸렌 블루 분해 반응 실험에 광촉매로서 사용하였다.

• Journal of the Korean Chemical Society
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• v.22 no.5
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• pp.281-288
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• 1978

Pseudo-first order rate constants $k_{obs}$ were determined for the reactions of naphthalenesulfonyl chlorides (1-NSC and 2-NSC) and anilines. The second order rate constant $k_2$ and third order catalytic $k_3$ were then determined from $k_{obs}$. For 1-NSC peri-hydrogen effect was observed. The large Brønsted ${\beta}$ and large negative slopes ${\rho}$ for the Hammett plots were obtained. These results with the unsually low values of activation parameters were consistent with the $S_AN$-elimination mechanism, but these can be equally well interpreted with the associative $S_N2$mechanism.

• The Korean Journal of Applied Statistics
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• v.15 no.1
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• pp.179-186
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• 2002

We usually execute the blocking under heterogeneity of experimental condition in response surface methodology. We can suggest the measure for evaluating nearly orthogonal blocking under second order models.

• Journal of the Korean Society of Food Science and Nutrition
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• v.31 no.1
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• pp.69-74
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• 2002

In the present study, we investigated the quality characteristic of ginseng cultured in bioreactor system and the optimum recipe condition of the liquid tea using cultured ginseng. The contents of soluble solid and crude saponin in cultured ginseng were 31.8% and 1.94%, respectively, which were lower than commercial ginseng. In the concentrated extract, crude saponin content was 4.77% and the contents of ginsenoside Rc, Re and Rg$_1$were 7.36, 4.40 and 1.75 mg/g, respectively. The ginsenoside Rb$_1$and Rb$_2$, main contents of commercial ginseng, were not detected. The optimum ranges of recipe on organoleptic properties of ginseng liquid tea were estimated on 9.0~10.4% of the extract, 6.8~8.1% of apple vinegar and 40% of fructose. The liquid tea using commercial ginseng showed higher scores of sensory lest than the liquid tea using cultured ginseng in bioreactor system at the given condition, 10% of the extract, 7% ofapple vinegar and 40% of fructose, with the same recipe condition ranges.

• Journal of the Korean Chemical Society
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• v.36 no.2
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• pp.174-179
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• 1992

Reaction of aniline and iodine in$CHCl_3,\;CH_2Cl_2 : CHCl_3$(1 : 1), and $CH_2Cl_2$ has been studied kinetically by using conductivity method, Pseudo first-order rate constants ($k_{obs}$) and second-order rate constants ($k_{obs}$/[aniline]) are dependent on the aniline concentration. Second-order rate constants obtained were increased with increasing aniline concentration. We analysed these results on the basis of formation of charge transfer complex as reaction intermediate. From the construction of react ion scheme and derivation of rate equation, we calculated equilibrium constants and activation parameters for the formation and transformation of charge transfer complex. The equilibrium constants were decreased by an increase in the dielectric constant of the solvent and the value is 1.7-3.7$M^{-1}$. The rate of transformation are markedly affected by the solvent polarity. ${\Delta}H^{\neq}$ is about 14.2kJ/mol, and ${\Delta}S^{\neq}$ is large negative value of -243J/mol K.

• Journal of Korea Water Resources Association
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• v.47 no.5
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• pp.483-490
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• 2014

The design procedures for a biological reactor and a secondary settling tank (SST) of an activated sludge system are based on the steady state design method (Ekama et al., 1986; WRC, 1984) and the 1-D flux theory design method (Ekama et al., 1997), respectively. This study combined both of the design procedures, to determine the optimum sludge concentration in the reactor and the best design with the lowest cost. The best design of the reactor volume and the SST diameter at the optimum sludge concentration were specified with varying wastewater and sludge characteristics, temperature, sludge retention time (SRT) and peak flow rate. The effects of the influent wastewater characteristics, such as substrate concentration and unbiodegradable particulate fraction, were found to be considerable, but the effect of unbiodegradable soluble fraction was to be negligible. The effects of sludge settling characteristics, were also significant. SRT, as an operating parameter, was found to be an important factor for determining the optimum sludge concentration. However, the effect of temperature was found to be small. Furthermore, for designing a large scale wastewater treatment plant, the number of reactors or SSTs could be estimated, by dividing the total reactor volume or SST area. The new combined design procedure, proposed in this research, will be able to allow engineers to provide the best design of an activated sludge system with the lowest cost.