• Journal of the Korean Society of Marine Environment & Safety
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• v.23 no.6
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• pp.661-668
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• 2017

The purpose of this study is to analyze the chemical reaction pathway for explosion accident of mixed cargo. The analysis used a structural scenario using event-tree analysis. Structural scenarios were constructed by estimating various chemical reaction paths in the content of the mixed cargo accident recorded in the written verdict. The analytical method was applied to three kinds of analysis: chemical analysis based on chemical theory, quantitative analysis using chemical reaction formula, and probabilistic analysis through questionnaire. As a result of analysis, the main pathway of the accident occurred in three ways: the path of explosion due to the reaction of concentrated sulfuric acid with water, the path of explosion due to the reaction of metal and mixed acid, and the path of explosion by synthesizing with special substances. This result is similar to the path recorded in the validation, and it leads to thar the proposed path analysis method is valid. The proposed method is expected to be applicable to chemical reaction path estimation of various chemical accidents.

• Journal of the Korean Chemical Society
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• v.41 no.4
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• pp.198-204
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• 1997

The rate constants for the hydrolysis of N-(2,4-dinitrophenyl)benzhydrazonyl bromide and its derivatives were determined by ultraviolet visible spectrophotometry at 20$^{\circ}C$ and a rate equation which could be applied over a wide pH range was obtained. On the basis of rate equations derived and judging from the solvent effect, substituent effect, salt effect, thermodynamic parameter, plausible mechanisms of hydrolysis have been proposed. It may be concluded that the hydrolysis through SN1 mechanism via carbonium ion intermdiate to pH 3.0, and pH 10.0, the hydrolysis proceeds through 1,3-dipolar or SN2 mechanism.

• Journal of the Korean Chemical Society
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• v.47 no.4
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• pp.423-426
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• 2003

• Proceedings of the Korea Water Resources Association Conference
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• 2019.05a
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• pp.106-106
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• 2019

많은 도심의 하천들은 오염물질의 유입에 취약하다. 최근 신소재 공학 등 첨단산업이 발전하게 되면서 유해화학물질의 유입문제는 더욱 대두되고 있으며, 실제로 최근 유해화학물질 유입사고 발생건수가 늘어나고 있다. 특히 국내 취수량의 90%는 지표수에서 취수하고 있어, 하천오염사고는 직접적인 피해로 이어지게 된다. 따라서 이러한 사고에 대응하기 위하여 수환경에 유입된 유해물질의 거동 매커니즘을 반영한 수질해석이 필요하다. 수체 내에 유입된 유해화학물질은 기본적으로 흐름에 따른 이송 확산을 하며 흡 탈착, 휘발, 침전 부유, 생화학 반응과 같은 다양한 반응과 함께 혼합거동을 한다. 특히 소수성물질의 경우 용해된 상태뿐만 아니라, 유사에 흡착된 상태로 수체에 존재하게 된다. 결국 유해화학물질의 거동을 해석하기 위해서는 유체의 흐름 해석뿐만 아니라 수체에 존재하는 유사의 이송 또한 해석해야한다. 본 연구에서는 흐름해석을 위하여 서울대에서 개발한 흐름모형(HDM-2D)을 사용하였으며, 부유사 거동모의를 위해 부유사거동모형(STM-2D)을 개발하였다. 또한 유해화학물질의 거동모의를 위해 서울대에서 개발한 수질모형(CTM-2D)에 생성/소멸항을 추가하였으며 흐름모형과 부유사모형과의 연계를 통해 유해화학물질의 혼합거동 수치모형을 개발하였다. 각 반응항(흡 탈착, 휘발, 침전 부유, 생화학 반응)을 수치모형에 반영 시에는 보통 두 계(물-토양, 물-공기) 사이의 선형 물질교환으로 이해된다. 따라서 물질의 각 반응 별 평형농도와 물질교환속도계수를 추정식을 통해 산정하여 사용하게 된다. 하지만 각 기작이 반영유무에 따라 계산시간 및 필요입력변수가 늘어나게 되므로, 유해화학물질 유입사고와 같은 빠른 대처가 필요한 경우 각 반응 텀의 유의성을 판단하여 모형에 반영여부를 결정을 통해 경제적인 모의를 할 수 있어야 한다. 이에 따라 본 연구에서는 개발된 모형의 각 매개변수들의 민감도를 분석하고, 흐름조건 및 물질의 특성에 따른 반응항의 유의성을 판단하였다. 본 연구에서는 개발된 모형(부유사거동모형, 유해화학물질의 혼합거동모형)은 해석해 및 현장 데이터와 비교검증을 통해 개발을 완료하였으며, 각 반응항의 민감도 분석을 통해 매개변수의 임계값을 결정하였다.

• Explosives and Blasting
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• v.33 no.3
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• pp.1-13
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• 2015

Accidents related to gas explosion are frequently happened in foreign countries and in Korea. For the evaluation and the analysis of gas explosions, TNT equivalent methods are used. In this study, the influence of the selection of chemical equation in TNT explosion and the selection of enthalpy of the products on the explosion energy, detonation pressure, velocity of detonation, and temperature was calculated. Depending on the chemical equations, the maximum detonation pressure can be 2 times higher than the minimum. As an example for applying TNT equivalent method, an explosion of methane gas in a confined volume was assumed. With the TNT equivalent, it was possible to predict the variation of peak overpressure and impulse with the distance from the explosion location.

• Korean Chemical Engineering Research
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• v.59 no.1
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• pp.77-84
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• 2021

To control hot spot in a plug flow reactor (PFR) is important for the yield and purity of products and safety. In this paper, coolant temperature is set as a state variable, and radial distributions of heat and mass are considered to model the PFR more realistic than without considering radial distributions. The model consists of three state variables, reactant concentration, reactant temperature, and the coolant temperature. The flow rate of the isothermal coolant is a manipulated variable. This paper shows that the controller considering the radial distributions of heat and mass is more effective than the controller without them. Assuming that u3,0 is 0.7, the suggested control equation was robust when St is bigger than 1.3, and Ac/A is smaller than 2.0. Under this condition, the hot spot temperature changed within the relative error of one percent when the temperature of input altered within the range of five percent.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.35 no.2
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• pp.465-470
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• 2015

The curing of epoxy asphalt mixture depends on the chemical reaction of epoxy resin and the curing agent. The curing level of epoxy asphalt mixture needs to be predicted in order to decide traffic opening time and to establish further construction plans. In this study, chemical analysis of the prediction model was executed to expand the applicability of the previous prediction model. Consequently, the curing level prediction model of epoxy asphalt concrete mixture was proposed using the concentration ratio and the acid value ratio. According to the results of outdoor curing experiments, the final prediction model showed that the correlation coefficient is greater than 0.971. Precise prediction results of different composition epoxy asphalt were obtained by reflecting the chemical composition ratios in the curing level prediction model.

• Korean Chemical Engineering Research
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• v.57 no.5
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• pp.666-671
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• 2019

Calcium carbonate involves three phases such as calcite, vaterite, and aragonite. Calcite and aragonite were more thermodynamically stable than vaterite. The synthesis of aragonite crystals by the reaction with sodium carbonate and calcium chloride solutions was investigated focusing on the effect of temperature and rpm in continuous crystallizer. In the batch crystallization test, calcite was synthesized by a relatively low temperature (under $40^{\circ}C$), but aragonite was formed at high temperature. In the continuous process with 100 rpm, no aragonite was found regardless of reaction temperature. But as increasing the stirring rate to 300 rpm and 500 rpm, the ratio of aragonite to calcite increased as increasing the temperature.

• Journal of the Korean Chemical Society
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• v.26 no.6
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• pp.407-413
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• 1982

The rate constants of the nucleophilic addition of cysteine to 3,4-methylenedioxyphenylmethylene malononitrile were determined by UV Spectrophotometry and a rate equation which can be applied over wide pH range was obtained. On the basis of rate equation, it may be concluded that the rate constants were dependent upon only the concentration of hydroxide ion above pH 9.0, however, below pH 6.0, the reaction were initiated by the addition of neutral cysteine molecule to carbon-carbon double bond and at pH 7.0~9.0, the addition of a neutral cysteine molecule and it's anion occurred competitively.

• Applied Chemistry for Engineering
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• v.34 no.2
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• pp.131-136
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• 2023

We developed a method to measure the concentration of highly concentrated colored samples using color coordinates. We present a color analysis to estimate the concentration of highly concentrated binary solutions with an empirical function and apply it to estimate the kinetics of a catalytic irreversible reaction of resazurin to resorufin. The developed method enabled one to measure the concentration of solutions whose range of concentrations is nonlinear and beyond the limit of UV-vis spectroscopic measurement directly without dilution.