• Bulletin of the Korean Chemical Society
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• v.31 no.6
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• pp.1583-1588
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• 2010

A single step fabrication process of carbon nanotube/Prussian Blue (CNT/PB) paste electrodes based on screen printing technology has been studied as an amperometric sensor for the determination of hydrogen peroxide and free chlorine. Compared to the classical carbon paste (CP) electrode, the CNT paste electrode greatly enhanced the response in the presence of hydrogen peroxide due to the electrocatalytic activity of the CNT. Based on the CNT/binder paste, PB was also incorporated into a network of CNT paste and characterized. The best electroanalytical properties of PB-mixed sensors to hydrogen peroxide were obtained with PB ratio of 10 wt % composition, which showed fast response time ($t_{90}{\leq}5$ s; 0.2 - 0.3 mM), low detection limit of 1.0 ${\mu}M$, good linear response in the range from $5.0{\times}10^{-5}$ - $1.0{\times}10^{-3}$ mol $L^{-1}$ ($r^2$ = 0.9998), and high sensitivity of -8.21 ${\mu}AmM^{-1}$. In order to confirm the enhanced electrochemical properties of CNT/PB electrode, the sensor was further applied for the determination of chlorine in water, which exhibited a linear response behavior in the range of 50 - 2000 ppb for chlorine with a slope of 1.10 ${\mu}Appm^{-1}$ ($r^2$ = 9971).

• Journal of the Korean Institute of Gas
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• v.19 no.5
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• pp.87-97
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• 2015

Accidents of HAZMAT transport vehicle are generally dealt by unskilled firefighters. As a result, firefighters became 2nd victims of accidents in some case because of this reason, and it is required to prepare an accident response guidelines against HAZMAT transport vehicle accidents. In this study, risk assessment methods and making methods of guidelines were investigated to make accident response guidelines of HAZMAT transport vehicle accidents. and It identifies hazards and combines with guideword for making guideline items. At last, we determine criteria or detailed methods by referring survey regulations and existed methods.

• Korea-Australia Rheology Journal
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• v.15 no.2
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• pp.97-105
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• 2003

In the previous paper (Hyun et al.,2002), we have investigated the shape of storage modulus (G') and loss modulus (G") of complex fluids under large amplitude oscillatory shear (LAOS) flow. As the strain amplitude increases, owever, the stress curve becomes distorted and some important information may be smothered during data processing. Thus we need to investigate the stress data more precisely and systematically. In this work, we have obtained the stress data using high performance ADC (analog digital converting) card, and investigated the nonlinear response of complex fluids, 4wt% xanthan gum (XG), 2 wt% PVA/ 1 wt% Borax, and 1 wt% hyaluronic acid (HA) solutions, using Fourier transformation (FT) rheology. Comparing the strain signals in time domain with FT parameters in frequency domain, we could illustrate the sensitivity and importance of FT rheology. Diverse and unique stress patterns were observed depending on the material system as well as flow environment. It was found that they are not the outcome of experimental deficiency like wall slip but characteristics of the material system. When nonlinear response of complex fluids is analyzed, the intensity and phase angle of higher harmonic contributions should be considered together, and the shape of the stress signal was found to be strongly dependent upon phase angle.ngle.

• Journal of the Korean Society of Marine Environment & Safety
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• v.8 no.1
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• pp.139-148
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• 2002

As the Busan harbor is getting susceptible to oil Pollution. the authors analyze the historical records of oil spill accidents and investigate the shoreline features. In addition. we evaluate the response capabilities and compute the required stockpiles of marine oil spill response with the worst case scenario in this area. As a result, it is shown that the recommendable oil spill response is to contain and mechanically recover all oils at sea surface in winter. while chemical dispersants can be used in summer with mechanical containment and recovery, and it is also found that off-shore booms of 3,000m and off-shore skimmers of 986MT/hour recovery rate should be stockpiled with 10,000∼60,000 liters of concentrate chemical dispersant and small amount of synthetic organic sorbents for possible use.

• Journal of Environmental Health Sciences
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• v.47 no.2
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• pp.155-165
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• 2021

Objectives: Acute exposure to high concentrations of chemicals can occur when a chemical accident takes place. As such exposure can cause ongoing environmental pollution, such as in the soil and groundwater, there is a need for a tool that can assess health effects in the long term. The purpose of this study was assessing the health risks of residents living near a chemical accident site due to long-term exposure while considering the temporal concentration changes of the toxic chemicals leaked during the accident until their extinction in the environment using a multimedia environmental dynamics model. Methods: A health risk assessment was conducted on three cases of formaldehyde chemical accidents. In this study, health risk assessment was performed using a multimedia environmental dynamics model that considers the behavior of the atmosphere, soil, and water. In addition, the extinction period of formaldehyde in the environment was regarded as extinction in the environment when the concentration in the air and soil fell below the background concentration prior to the accident. The subjects of health risk assessment were classified into four groups according to age: 0-9 years old, 10-18 years old, 19-64 years old, and over 65 years old. Carcinogenic risk assessment by respiratory exposure and non-carcinogenic risk assessment by soil intake were conducted as well. Results: In the assessment of carcinogenic risk due to respiratory exposure, the excess carcinogenic risk did not exceed 1.0×10-6 in all three chemical accidents, so there was no health effect due to the formaldehyde chemical accident. As a result of the evaluation of non-carcinogenic risk due to soil intake, none of the three chemical accidents had a risk index of 1, so there was no health effect. For all three chemical accidents, the excess cancer risk and hazard index were the highest in the age group 0-9. Next, 10-18 years old, 65 years old or older, and 19-64 years old showed the highest risk. Conclusion: This study considers environmental changes after a chemical accident occurs and until the substance disappears from the environment. It also conducts a health risk assessment by reflecting the characteristics of the long-term persistence and concentration change over time. It is thought that it is of significance as a health risk assessment study reflecting the exposure characteristics of the accident substance for an actual chemical accident.

• Journal of the Korean Chemical Society
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• v.57 no.6
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• pp.769-777
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• 2013

The effect of operating conditions (temperature and the partial pressures of H2 and CO) on the reaction rate of Fischer-Tropsch synthesis (FTS) were investigated by carrying out experiments according to a Box-Behnken design (BBD), and were mathematically modeled by using response surface methodology (RSM). The catalyst used was a nano-structured cobalt/manganese oxide catalyst, which was prepared by thermal decomposition. The rate of synthesis was measured in a fixed-bed micro reactor with $H_2/CO$ molar feed ratio of 0.32-3.11 and reactor pressure in the range of 3-9.33 bar at space velocity of $3600h^{-1}$ and a temperature range of 463.15-503.15 K, under differential conditions (CO conversion below 2%). The results indicated that in the present experimental setup, the temperature and the partial pressure of CO were the most significant variables affecting reaction rate. Based on statistical analysis the quadratic model of reaction rate of FTS was highly significant as p-value 0.0002.

• Korean Chemical Engineering Research
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• v.56 no.3
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• pp.416-420
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• 2018

A comprehensive kinetic study has been conducted on dimethyl carbonate synthesis by transesterification reaction of ethylene carbonate with methanol. An alkali base metal (KOH) was used as catalyst in the synthesis of DMC, and its catalytic ability was investigated in terms of kinetics. The experiment was performed in a batch reactor at atmospheric pressure. The reaction orders, the activation energy and the rate constants were determined for both forward and backward reactions. The reaction order for forward and backward reactions was 0.87 and 2.15, and the activation energy was 12.73 and 29.28 kJ/mol, respectively. Using the general factor analysis in the design of experiments, we analyzed the main effects and interactions according to the MeOH/EC, reaction temperature and KOH concentration. DMC yield with various reaction conditions was presented for all ranges using surface and contour plot. Furthermore, the optimal conditions for DMC yield were determined using response surface method.

• Bulletin of the Korean Chemical Society
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• v.33 no.2
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• pp.685-688
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• 2012

• Bulletin of the Korean Chemical Society
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• v.25 no.10
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• pp.1474-1476
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• 2004

A sodium ion- selective electrode based on dibenzopyridino-18-crown-6 as membrane carrier was successfully prepared. The electrode exhibits a Nernstian response for $Na^+$ ions within the concentration range of $1.0\;{\times}\;10^{-4}-1.0\;{\times}\;10^{-1}$ M. The response time of the sensor is 20 s. The sodium ion-selective electrode exhibited comparatively good selectivities with respect to alkali, alkaline earth and some transition metal ions.

• Bulletin of the Korean Chemical Society
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• v.26 no.10
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• pp.1555-1559
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• 2005

High-performance fluorescent probes which exhibit either on/off or dual color fluorescence switching in response to the presence of organic vapors with a rapid response, a high sensitivity and a high-contrast on/off signaling ratio were demonstrated on the basis of the vapor-controlled AIEE phenomenon.