• Carbon letters
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• v.27
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• pp.81-89
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• 2018

The present study aimed to prepare a novel efficient flame retardant additive for polypropylene. The new flame retardant was prepared by chemical grafting of melamine to graphene oxide with the aid of thionyl chloride. Fourier-transform infrared spectroscopy and thermogravimetric analysis proved that melamine had been successfully grafted to the graphene oxide. The modified graphene oxide was incorporated into polypropylene via solution mixing followed by anti-solvent precipitatio. Homogeneous distribution as well as exfoliation of the nanoplatelets in the polymer matrix was observed using transmission electron microscopy. Thermogravimetric analysis showed a significant improvement in the thermo-oxidative stability of the polymer after incorporating 2 wt% of the modified graphene oxide. The modified graphene oxide also enhanced the limiting oxygen index of the polymer. However, the amount of improvement was not enough for the polymer to be ranked as a self-extinguishing material. Cone calorimetry showed that incorporating 2 wt% of the modified graphene oxide lowered total heat release and the average production rate of carbon monoxide during burning of the polymer by as much as 40 and 35%, respectively. Hence, it was concluded that the new flame retardant can retard burning of the polymer efficiently and profoundly reduce suffocation risk of exposure to burning polymer byproducts.

• Toxicological Research
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• v.12 no.2
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• pp.271-275
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• 1996

Carcinogenic potential of HPV-16 DNA and NNK in a human keratinocyte cell line was assessed to study effects of viral-chemical interaction. Human cells were transfected with HPV-16 DNA and 6 clonal cell lines were subsequently obtained. Clonal line-3 and 6 at passage 7 showed characteristics of tumor cells such as increases of saturation density, soft-agar colony formation, cell aggregation and foci appearance. Among cells treated with 1$\mu M$, 10$\mu M$, 100$\mu M$ or 1 mM of NNK for 4 weeks, 100$\mu M$ treatment showed most tumorigenic characteristics at passage 7. These results indicate that either HPV-16 or NNK alone is tumorigenic in this in human in vitro model. When cells transfected with HPV-16 were subsequently exposed by 100 uM NNK for 4 weeks, all the clonal cells except clone-1 showed higher levels of tumor cell characteristics than HPV-16 DNA or NNK exposure alone. Clonal line-6, the most tumorigenic cells, showed higher transcriptional level of fibronectin and lower level of TGF-$\beta_1$, as compared to control cells, suggesting that alteration of growth factor or extracellular matrix may play a role in carcinogenesis process induced by HPV-16 and NNK. Taken together, the present study indicates that viral-chemical interactions between HPV-16 DNA and NNK enhance carcinogenic potentials of human cells and implies that smoking among people infected with human papillomavirus may pose an additional risk of causing cancer.

• Journal of the Korea Society of Computer and Information
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• v.25 no.8
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• pp.151-157
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• 2020

The first thing we can consider to prevent juvenile delinquency is to punish those criminals. However, this is not always the proper solution. In consideration to the feature of juvenile period when they lack in proper judgment it is better to provide education than punishment so that they are not branded as criminals in our society. Also, by returning to the society, they can obtain social techniques and obtain the opportunity of making contribution to the society, which is also good for their career development. Combining international examples on juvenile delinquency prevention, there is a need to comprehensively evaluate level of probation and risk exposure of juvenile based on placement matrix of comprehensive strategy program in the US. Also, control solution by juvenile crime development phase should be made. In terms of control treatment based on crime phase, crime history should be considered when applying control. For the subject of preventing juvenile crime, it shouldn't be legal organizations like before but shall be home, school, local society, and legal organization together.

• Journal of the Korea Institute of Building Construction
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• v.18 no.1
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• pp.59-65
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• 2018

Radon gas is a colorless, odorless, tasteless gas that occurs when uranium, a natural radioactive material in rocks and soils, collapses. 85% of the annual radiation exposure of the human body is due to natural radiation, of which 50% is radon. According to the US Environmental Protection Agency (EPA) survey, 62 out of 1,000 smokers and 7 out of 1,000 nonsmokers are exposed to lung cancer when exposed to radon gas for a long time. In order to reduce the risk of radon gas, activate carbon was used to fabricate matrix, and the pore properties and radon reduction properties were investigated. When the activate carbon was used, the radon gas concentration was drastically reduced and the graph was changed as the measurement period became longer. The pore distribution and microporous properties, which are one of the material properties of activate carbon, can be grasped.

• Journal of Environmental Health Sciences
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• v.43 no.4
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• pp.307-313
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• 2017

Objectives: Chemicals derived from various environment media contaminates food across the food supply chain. In Korea, levels of contaminants in food have been sporadically measured by monitoring programs of different government agencies. There is difficulty with data compilation and integrated analysis across media. Therefore, the aim of this study was to propose an overall integrated database and analytical platform design for the 'ECO-FOOD NET (Environmental COntaminant reduction platform for FOOD through an interagency collaboration NETwork)', a tool to support the reduction of environmental contaminants in food. Methods: We developed a new data structure and standardized protocols for the compilation of integrated data. In addition, we conducted subject-oriented logical and physical relational database modeling and created the architecture design of the platform. Results: We established a standardized code system related to exposure media and route, analysis method and food matrix. In addition, we designed the seven software modules of 'About the System', 'Introduction to Interagency Work', 'Media-Chemicals Profiles', 'Method Bank', 'Monitoring Data Base', 'Integrated Media Analysis', and 'Risk-Benefit Analysis'. Conclusions: This study will contribute to decision-making as a tool for executing risk management, such as sustainable reduction policies of contaminants in food.

• Biomedical Science Letters
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• v.15 no.4
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• pp.309-317
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• 2009

Occupational exposure to inorganic dusts such as coal and silica has been identified as a chronic obstructive pulmonary disease (COPD) risk factor. This risk factor causes lung inflammation and protease-antiprotease imbalance. This abnormal inflammatory response of the lung induces parenchymal tissue destruction and leads to progressive airflow limitation that is characteristics of COPD. The aim of this study was to determine the relationship of proteases such as neutrophil elastase (NE) and matrix metalloproteinase (MMP)-9 and antiproteases such as alpha-1 antitrypsin (AAT) and tissue inhibitors of metalloproteinase (TIMP)-1 with lung function. The study population contained 223 retired workers exposed to inorganic dusts. We performed lung function test, including percent of forced expiratory volume in one second ($%FEV_1$) predicted and $%FEV_1$/forced vital capacity (FVC). We analyzed serum MMP-9, AAT, TIMP-1 and plasma NE concentrations by sandwich enzyme immunoassay. NE, AAT, and TIMP-1 concentrations in workers, who had $%FEV_1$<80% predicted, were higher than those of workers who had $%FEV_1{\geq}80%$ (P<0.05). Both AAT and TIMP-1 concentrations in workers with airflow limitation were higher than those of workers with normal airflow (P<0.05). $%FEV_1$ predicted showed significant negative correlation with AAT (r=-0.255, P<0.0l), TIMP-1 (r=-0.232, P<0.01), and NE (r=-0.196, P<0.01). $%FEV_1$/FVC predicted showed significant negative correlation with NE (r=-0.172, P<0.05). From the results of stepwise multiple regression analysis about $%FEV_1$ and $%FEV_1$/FVC, significant independents were NE (r=-0.135, P=0.001) and AAT (r=-0.100, P=0.013) in $%FEV_1$, and NE (r=-0.160, P=0.014) in $%FEV_1$/FVC. In the present study, there were significant correlations between airflow limitation and protease concentration and between airflow limitation and antiprotease concentration. Serum protease and antiprotease concentrations, however, may be affected by the biological and inflammatory responses. It is necessary to evaluate specimens more reflected the effects of proteases and antiproteases in the lung such as lung tissue, bronchoalveolar lavage fluid, and exhaled breath condensate (EBC).

• Journal of Food Hygiene and Safety
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• v.36 no.1
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• pp.24-33
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• 2021

For this study, we surveyed concentrations of 8 mycotoxins (aflatoxin B1, B2, G1, G2, ochratoxin A, fumonisin B1, B2 and zearalenone) in agricultural products used for food and medicine by liquid chromatography-tandem mass spectrometry and conducted a risk assessment. Samples were collected at the Yangnyeong Market in Seoul, Korea, between January and November 2019. Mycotoxins were extracted from these samples by adding 0.1% formic acid in 50% acetonitrile and cleaned up by using an ISOLUTE Myco cartridge. The method was validated by assessing its matrix effects, linearity, limit of detection (LOD), limit of quantification (LOQ), recovery and precision using four representative matrices. Matrix-matched standard calibration was used for quantification and the calibration curves of all analytes showed good linearity (r2>0.9999). LODs and LOQs were in the range of 0.02-0.11 ㎍/kg and 0.06-0.26 ㎍/kg, respectively. Sample recoveries were from 81.2 to 118.7% and relative standard deviations lower than 8.90%. The method developed in this study was applied to analyze a total of 187 samples, and aflatoxin B1 was detected at the range of 1.18-7.29 ㎍/kg (below the maximum allowable limit set by the Ministry of Food and Drug Safety, MFDS), whereas aflatoxin B2, G1 and G2 were not detected. Mycotoxins that are not regulated presently in Korea were also detected: fumonisin (0.84-14.25 ㎍/kg), ochratoxin A (0.76-17.42 ㎍/kg), and zearalenone (1.73-15.96 ㎍/kg). Risk assessment was evaluated by using estimated daily intake (EDI) and specific guideline values. These results indicate that the overall exposure level of Koreans to mycotoxins due to the intake of agricultural products used for food and medicine is unlikely to be a major risk factor for their health.

• Archives of Plastic Surgery
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• v.44 no.6
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• pp.516-522
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• 2017

Background Implant-based breast reconstruction is being performed more frequently, and implants are associated with an increased risk of infection. We reviewed the clinical features of cases of implant infection and investigated the risk factors for breast device salvage failure. Methods We retrospectively analyzed 771 patients who underwent implant-based breast reconstruction between January 2010 and December 2016. Age, body mass index, chemotherapy history, radiation exposure, and smoking history were assessed as potential risk factors for postoperative infection. We also evaluated the presence and onset of infection symptoms, wound culture pathogens, and other complications, including seroma, hematoma, and mastectomy skin necrosis. Additionally, we examined the mastectomy type, the use of acellular dermal matrix, the presence of an underlying disease such as hypertension or diabetes, and axillary node dissection. Results The total infection rate was 4.99% (58 of 1,163 cases) and the total salvage rate was 58.6% (34 of 58). The postoperative duration to closed suction drain removal was significantly different between the cellulitis and implant removal groups. Staphylococcus aureus infection was most frequently found, with methicillin resistance in 37.5% of the cases of explantation. Explantation after infection was performed more often in patients who had undergone 2-stage expander/implant reconstruction than in those who had undergone direct-to-implant reconstruction. Conclusions Preventing infection is essential in implant-based breast reconstruction. The high salvage rate argues against early implant removal. However, when infection is due to methicillin-resistant S. aureus and the patient's clinical symptoms do not improve, surgeons should consider implant removal.

• Journal of Preventive Medicine and Public Health
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• v.37 no.4
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• pp.381-389
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• 2004

Objective : To compare the efficacy between SKI306X and Diclofenac by using generalized estimating equations (GEE) methodology in the analysis of correlated bivariate binary outcome data in Osteoarthritis (OA) diseases. Methods : A randomized, double-blind, active comparator-controlled, non-inferiority clinical trial was conducted at 5 institutions in Korea with the random assignment of 248 patients aged 35 to 75 years old with OA of the knee and clinical evidence of OA. Patients were enrolled in this study if they had at least moderate pain in the affected knee joint and a score larger than 35mm as assessed by VAS (Visual Analog Scale). The main exposure variable was treatment (SKI 306X vs. Diclofenac) and other covariates were age, sex, BMI, baseline VAS, center, operation history (Yes/No), NSAIDS (Y/N), acupuncture (Y/N), herbal medicine (Y/N), past history of musculoskeletal disease (Y/N), and previous therapy related with OA (Y/N). The main study outcome was the change of VAS pain scores from baseline to the 2nd and 4th weeks after treatment. Pain scores were obtained as baseline, 2nd and 4th weeks after treatment. We applied GEE approach with empirical covariance matrix and independent(or exchangeable) working correlation matrix to evaluate the relation of several risk factors to the change of VAS pain scores with correlated binary bivariate outcomes. Results : While baseline VAS, age, and acupuncture variables had protective effects for reducing the OA pain, its treatment (Joins/Diclofenac) was not statistically significant through GEE methodology (ITT:aOR=1.37, 95% CI=(0.8200, 2.26), PP:aOR=1.47, 95% CI=(0.73, 2.95)). The goodness-of-fit statistic for GEE (6.55, p=0.68) was computed to assess the adequacy of the fitted final model. Conclusions : Both ANCOVA and GEE methods yielded non statistical significance in the evaluation of non-inferiority of the efficacy between SKI306X and Diclofenac. While VAS outcome for each visit was applied in GEE, only VAS outcome for the fourth visit was applied in ANCOVA. So the GEE methodology is more accurate for the analysis of correlated outcomes.

• Journal of the Korean Applied Science and Technology
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• v.30 no.1
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• pp.116-126
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• 2013

Glycol ethers are a group of solvents based on alkyl ethers of ethylene glycol commonly used in paints. These solvents typically have a higher boiling point, together with the favorable solvent properties of lower-molecular weight ethers and alcohols. The word "Glycol ethers" was registered as a United States trademark by Union Carbide Corp. Typically, glycol ethers are found in pharmaceuticals, sunscreens, cosmetics, inks, dyes and water based paints. On the other hand, glycol ethers are used in degreasers, cleaners, aerosol paints and adhesives. Most glycol ethers are relatively water soluble, biodegradable and only a few are considered toxic. Therefore, they are unlikely to pose an adverse risk to the environment. Recent study suggests that occupational exposure to glycol ethers is related to low motile sperm count in men, but the finding has been disputed by others. In this study, skin permeation of 3 types glycol ethers were studied in vitro using matrix such as solvent and detergent. The absorption of glycol ethers[methyl glycol ethers(MC), ethyl glycol ethers(EC) and butyl glycol ethers(BC)] has been measured in vitro through rat skin. Epidermal membranes were set up in Franz diffusion cells and their permeability to PBS measured to establish the integrity of the skin before the glycol ethers were applied to the epidermal surface. Absorption rates for each glycol ethers were determined and permeability assessment made to quantify any irreversible alterations in barrier function due to contact with the esters. Types of glycol ethers in vitro experimental results on MC> EC> BC quickly appeared in the following order: skin permeation was beneficial to the skin permeation small molecular weight, the difference in chemical structure, such as hydrophilic, because with the partition coefficient and solubility mechanisms and passive diffusion to increase the speed at which transmission is considered.