• Applied Chemistry for Engineering
• /
• v.32 no.1
• /
• pp.75-82
• /
• 2021

This study investigated the fire risk assessment of woods and plastics for construction materials, focusing on the fire performance index-III (FPI-III), fire growth index-III (FGI-III), and fire risk index-IV (FRI-IV) by a newly designed method. Japanese cedar, red pine, polymethylmethacrylate (PMMA), and polyvinyl chloride (PVC) were used as test pieces. Fire characteristics of the materials were investigated using a cone calorimeter (ISO 5660-1) equipment. The fire performance index-III measured after the combustion reaction was found to be 1.0 to 15.0 with respect to PMMA. Fire risk by fire performance index-III increased in the order of PVC, red pine, Japanese cedar, and PMMA. The fire growth index-III was found to be 0.5 to 3.3 based on PMMA. Fire risk by fire growth index-III increased in the order of PVC, PMMA, red pine, and Japanese cedar. COpeak concentrations of all specimens were measured between 106 and 570 ppm. In conclusion, it is understood that Japanese cedar with a low bulk density and PMMA containing a large amount of volatile organic substances have a low fire performance index-III and high fire growth index-III, and thus have high fire risk due to fire. This was consistent with the fire risk index-IV.

• The Journal of the Korea Contents Association
• /
• v.21 no.4
• /
• pp.678-687
• /
• 2021

Styrene is a commercially important chemical used mainly in the production of raw materials and plastics. To determine the effect of styrene on hepatic activities of antioxidant enzymes, styrene was treated to Sprague-Dawley rats at 50 mg/kg, 200 mg/kg and 400 mg/kg (i.p) twice a day for 4 days. There were determined the significantly increased activities of serum AST (aspartate aminotransferase), ALT (alanine aminotransferse), and the increased content of MDA (malondialdehyde) at the dose of 400 mg/kg compared to the control. The hepatic activities of XO (xanthine oxidase) and CYPdAH (cytochrome P450 dependant aniline oxidase) in the dose of 400 mg/kg compared to the dose of 200 mg/kg were more increased, which means the excessive ROS (reactive oxygen species)s were produced during Phase I. In addition, significantly decreased were rates of the hepatic activities of GPx (glutathione peroxidase), CAT (catalase), SOD (superoxide dismutase) and GST (glutathione S-transferase) at the dose of 400 mg/kg compared to the control. And, the group at the dose of 400 mg/kg showed more significantly decreased GSH (glutathione) level than the group at the dose of 200 mg/kg. The decrease in GSH could ascribe to the toxic metabolites of styrene, such as styrene oxide. In conclusion, these results indicate that the excessive ROSs and the toxic metabolites of styrene may result in the hepatotoxicity, and be related to their imbalanced activities for antioxidant enzymes.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.26 no.6
• /
• pp.834-841
• /
• 2022

Recently, applying artificial intelligence technologies in various fields of production has drawn an upsurge of research interest due to the increase for smart factory and artificial intelligence technologies. A great deal of effort is being made to introduce artificial intelligence algorithms into the defect detection task. Particularly, detection of defects on the surface of metal has a higher level of research interest compared to other materials (wood, plastics, fibers, etc.). In this paper, we compare and analyze the speed and performance of defect classification by combining machine learning techniques (Support Vector Machine, Softmax Regression, Decision Tree) with dimensionality reduction algorithms (Principal Component Analysis, AutoEncoders) and two convolutional neural networks (proposed method, ResNet). To validate and compare the performance and speed of the algorithms, we have adopted two datasets ((i) public dataset, (ii) actual dataset), and on the basis of the results, the most efficient algorithm is determined.

• Journal of Food Hygiene and Safety
• /
• v.38 no.4
• /
• pp.228-235
• /
• 2023

Peanut is a well-known food allergen that causes adverse reactions ranging from mild urticaria to life-threatening anaphylaxis. Consumers suffering from peanut allergies should thus avoid consuming undeclared peanuts in processed foods. Therefore, effective cleaning methods are needed to remove food allergens from manufacturing facilities. To address this, wet cleaning methods with washing water at different temperatures, abstergents (peracetic acid, sodium bicarbonate, dilute sodium hypochlorite, detergent), and cleaning tools (brush, sponge, paper towel, and cotton) were investigated to remove peanuts from materials used in food manufacture, including plastics, wood, glass, and stainless steel. Peanut butter was coated on the surface of the glass, wood, stainless steel, and plastic for 30 min and cleaned using wet cleaning. The peanut residue on the cleaned surfaces was swabbed and determined using an optimized enzyme-linked immunosorbent assay (ELISA). Cleaning using a brush and hot water above 50℃ showed an effective reduction of peanut residue from the surface. However, removing peanuts from wooden surfaces was complicated. These results provide information for selecting appropriate materials in food manufacturing facilities and cleaning methods to remove food allergens. Additionally, the cleaning methods developed in this study can be applied to further research on removing other food allergens.

• Clean Technology
• /
• v.29 no.3
• /
• pp.185-192
• /
• 2023

This study was conducted to obtain basic process simulation data before conducting pyrolysis experiments for the development of a thermochemical conversion system by recirculation of heat carrier and gases thereby. In this study, polypropylene (PP) was used as a pyrolysis sample material as an alternative to waste plastics, and fluid sand was used as a heat transfer medium in the system. Manganese (Mn) was chosen as the catalyst for the pyrolysis experiment, and the catalyst pyrolysis was performed by impregnating it in the sand. The basic properties of PP were analyzed using a thermogravimetric analyzer (TGA), and liquid oil was generated through catalytic pyrolysis under a nitrogen atmosphere at 600℃. The carbon number distribution of the generated liquid oil was confirmed by GC/MS analysis. In this study, the effects of the presence and the amount of Mn loading on the yield of liquid oil and the distribution of hydrocarbons in the oil were investigated. When Mn/sand was used, the residue decreased and the oil yield increased compared to pyrolysis using sand alone. In addition, as the Mn loading increased, the ratio of C₆~C₉ range gasoline in the liquid oil gradually increased, and the distribution of diesel and heavy oil with more carbon atoms than C₁₀ in the oil decreased. In conclusion, it was found that using Mn as a catalyst and changing the amount of Mn could increase the yield of liquid oil and increase the gasoline ratio in the product.

• Applied Chemistry for Engineering
• /
• v.34 no.2
• /
• pp.126-130
• /
• 2023

In response to environmental demands, pyrolysis is one of the practical methods for obtaining reusable oils from waste plastics. However, the waste plastic pyrolysis oils (WPPO) are consumed as low-grade fuel oil due to their impurities. Thus, this study focused on the upgrading method to obtain naphtha catalytic cracking feedstocks from WPPO by the hydroprocessing, including hydrotreating and hydrocracking reaction. Especially, various transition metal sulfides supported catalysts were investigated as hydrotreating and hydrocracking catalysts. The catalytic performance was evaluated with a 250 ml-batch reactor at 370~400 ℃ and 6.0 MPa H₂. Sulfur-, nitrogen-, and chlorine-compounds in WPPO were well eliminated with nickel-molybdenum/alumina catalysts. The NiMo/ZSM-5 catalyst has the highest naphtha yield.

• Journal of Life Science
• /
• v.33 no.4
• /
• pp.371-381
• /
• 2023

Endocrine disrupting chemicals (EDCs), used in a variety of products in modern society, are hormone-like substances that cause various diseases. Humans are exposed to EDCs through their inclusion in pesticides, plastics, cosmetics, detergents, and drugs. Bisphenol A (BPA), one of the representative endocrine disruptors, is an estrogen-like substance that has been widely used commercially in plastic and epoxy resins. BPA is a chemical that can disrupt the endocrine system, leading to reduced reproductive function, obesity, cancer, and neurodevelopmental disorders. Since the adverse health effects of BPA began to be reported the use of BPA has been regulated worldwide. Various alternatives to BPA have been widely used worldwide; representatively, bisphenol S (BPS) and bisphenol F (BPF) are the most commonly used in commercial contexts. BPS and BPF may cause endocrine-disrupting effects like those of BPA due to their similar chemical structures. Recent studies have reported that BPS and BPF disrupt the neurodevelopmental process and cause neurodevelopmental disorders. Therefore, future studies will be required for safety verification of BPA alternatives and the development of new alternatives to BPA for brain health. In this review, we reviewed the effects of BPA and the alternatives, BPS and BPF, on the nervous system.

• Environmental and Resource Economics Review
• /
• v.31 no.1
• /
• pp.1-30
• /
• 2022

This study is to investigate consumers' acceptance and their willingness to pay for clothes made of materials with low microplastic emissions as an alternative to synthetic fibers made of plastics by applying the contingent valuation method. A nationwide web-based survey was conducted for 1,052 respondents proportional to region, age, and gender during February 2021. More than 75% of the sample expressed intentions to purchase microplastic emission-reducing clothing instead of synthetic fiber clothing, and more than 80% of them have stated their willingness to pay for additional prices. A variation of Heckman's sample selection model was adopted to estimate factors affecting respondents' intentions to pay for additional prices, in which the probit model of intentions to purchase the clothing with alternative materials was used as a sample selection equation. While respondents were sensitive to the amounts of price increases suggested in the CV scenario, they expressed high acceptance and preferences for eco-friendly materials regardless of the microplastic emission-reducing levels. Consumers in the circular economy were willing to pay for the range of 41,000 to 51,000 won for a pair of clothing made with microplastic emission-reducing materials. In addition, as the microplastic emission-reducing rate has increased from 50% to 80%, the willingness to pay estimates were also significantly increased, ranging from 41,000~50,500 to 42,000~51,700 won.

• Composites Research
• /
• v.36 no.2
• /
• pp.126-131
• /
• 2023

Growing environmental concerns regarding pollution caused by conventional plastics have increased interest in biodegradable polymers as alternative materials. The purpose of this study is to develop a 100% biodegradable nanocomposite material by introducing organic nucleating agents into the biodegradable and thermoplastic resin, poly(lactic acid), to improve its properties. Accordingly, cellulose nanofibers, an eco-friendly material, were adopted as a substitute for inorganic nucleating agents. To achieve a uniform dispersion of cellulose nanofibers (CNFs) within PLA, the aqueous solution of nanofibers was lyophilized to maintain their fibrous shape. Then, they were subjected to primary mixing using a twin-screw extruder. Test specimens with double mixing were then produced by injection molding. Differential scanning calorimetry was employed to confirm the reinforced physical properties, and it was found that the addition of 1 wt% CNFs acted as a reinforcing material and nucleating agent, reducing the cold crystallization temperature by approximately 14℃ and increasing the degree of crystallization. This study provides an environmentally friendly alternative for developing plastic materials with enhanced properties, which can contribute to a sustainable future without consuming inorganic nucleating agents. It serves as a basis for developing 100% biodegradable green nanocomposites.

• Analytical Science and Technology
• /
• v.21 no.6
• /
• pp.443-458
• /
• 2008

Brominated flame retardants (BFRs) are chemical compounds that inhibit the combustion of organic materials by scavenging free radicals that would otherwise encourage the spread of flames. These compounds are found in a wide variety of materials including paints, plastics, textiles, furniture and electronics. Mounting evidence, however, suggests that the non-reactive BFRs can easily leach into the environment and pose significant environmental and health concerns. PBDDs/PBDFs are often formed in the process of manufacturing brominated flame retardants and from the combustion of waste products containing flame retardants BFR. Therefore, this paper describes the general characteristics, management status, residual concentration in environments and analytical method.