• 한국식품과학회지
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• 제45권6호
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• pp.785-790
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• 2013

The purpose of this study was to investigate the hazards from onions and their cultivation areas. A total of 32 samples were collected from onion farms and tested for biological (sanitary indicators, and pathogenic bacteria and fungi) and chemical (heavy metals and pesticide residues) hazards. Aerobic bacteria and coliforms were detected at a level of 0.2-7.1 log CFU/g (or mL) in the soil and agricultural water, 1.6-3.6 log CFU/g on surface of the onion, 0.0-6.0 log CFU/hand (or $cm^2$) on the workers' hands, clothes, and gloves, and 4.7 log $CFU/cm^2$ on the onion bags. Fungi were detected at a level of 0.0-5.0 log CFU/g (or mL, hand, or 100 $cm^2$) in all the samples. Staphylococcus aureus was detected at a level of 1.2 log CFU/hand on the workers' hands, the detection level of Bacillus cereus was up to 4.8 log CFU/g in the soil. However, Escherichia coli (and in particular strain O157:H7), Listeria monocytogenes, and Salmonella spp. were not detected. Although heavy metals were detected in the environment (in soil and agricultural water) and pesticide residues were detected in onion, the levels were lower than the regulation limits.

• Asian-Australasian Journal of Animal Sciences
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• 제17권12호
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• pp.1736-1740
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• 2004

Since the application of relatively high levels of heavy metals in the compost poses a potential hazard to plants and animals, the content of heavy metals in the compost with animal manure is important to know if it is as a fertilizer. Measurement of heavy metals content in the compost by chemical methods usually requires numerous reagents, skilled labor and expensive analytical equipment. The objective of this study, therefore, was to explore the application of near-infrared reflectance spectroscopy (NIRS), a nondestructive, cost-effective and rapid method, for the prediction of heavy metals contents in compost. One hundred and seventy two diverse compost samples were collected from forty-seven compost facilities located along the Han river in Korea, and were analyzed for Cr, As, Cd, Cu, Zn and Pb levels using inductively coupled plasma spectrometry. The samples were scanned using a Foss NIRSystem Model 6500 scanning monochromator from 400 to 2,500 nm at 2 nm intervals. The modified partial least squares (MPLS), the partial least squares (PLS) and the principal component regression (PCR) analysis were applied to develop the most reliable calibration model, between the NIR spectral data and the sample sets for calibration. The best fit calibration model for measurement of heavy metals content in compost, MPLS, was used to validate calibration equations with a similar sample set (n=30). Coefficient of simple correlation (r) and standard error of prediction (SEP) were Cr (0.82, 3.13 ppm), As (0.71, 3.74 ppm), Cd (0.76, 0.26 ppm), Cu (0.88, 26.47 ppm), Zn (0.84, 52.84 ppm) and Pb (0.60, 2.85 ppm), respectively. This study showed that NIRS is a feasible analytical method for prediction of heavy metals contents in compost.

• 한국환경독성학회:학술대회논문집
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• 한국환경독성학회 2003년도 추계국제학술대회
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• pp.174-174
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• 2003

There are many synthetic chemicals, such as di(2-ethylhexyl) phthalate (DEHP) and dibutyl phthalate (DBP), used in chemical reaction processes in industry. The establishment of toxicity and detection of synthetic chemicals that may pose a genetic hazard in our enviornment is subjects of great concern at present DEHP, a ubiquitous phthalate plasticizer, induces a wide range of developmental and reproductive toxicities in mammals. DEHP belongs to the large diverse class of peroxisome proliferator compounds, which include herbicides, hypolipidemic drugs. DBP is a plasticizer used to products containing nitrocellulose, polyvinyl acetate, and polyvinyl chloride such as food wraps and blood bags. DBP is also used in cosmetics as a solvent and fixative for perfumes, a suspension agent for solids, an antifoamer, a skin emollient, and hair spray The present study was performed to examine patterns of gene expression in MCF-7 cells following DEHP and DBP exposure. Changes in gene expression were determined by microarray analysis using KISTCHIP-400 including 401 endocrine related genes based on public database and research papers. Of the genes analysis, we determined that genes detected by array showed a 2-fold or greater change in their expression level(increase or decrease). The results of this study demonstrate that a number of genes were differentially expressed in MCF-7 cells but these changes were not significant. Therefore, we keep going this study using microarray analysis and future studies will examine changes of gene expression on time-course and does treatment in variable cell lines.

• 대한수의학회지
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• 제60권3호
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• pp.105-108
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• 2020

These days abattoirs' hygiene of Korea is regulated by Hazzard Analysis Critical Control Point (HACCP). Although 20 years have been left since first HACCP was adjusted in Korea, 12% of abattoirs got inconsistence on evaluations. Food poisoning caused by bacteria feces like pathogenic Escherichia coli and Salmonella has not decreased. These bacteria on meat cross-contaminate at the abattoir. Therefore, field verification of abattoir's critical control point (CCP) and experiments to find alternative ways of the CCP were conducted. The aerobic bacteria were measured before and after high-pressure water based washing process set as CCP in most abattoirs. Four parts of cattle carcasses were selected to apply sponge-swab method. The effects were < 1 log reduction which is not significant. Lactic acid (LC), chlorine dioxide (ClO₂) and slightly acidic electrolyzed water (SAEW) were used to measure the effect of reducing bacteria on beef by the different time. LC has 1.24-2.02 log reduction for aerobic bacteria. ClO₂ has 1.44-1.96 log reduction for aerobic bacteria. SAEW has 1.1-1.91 log reduction for aerobic bacteria. There was significant difference according to concentrations (p < 0.05). This study presents legitimacy for hygiene improvement of CCP by field verification. In addition, chemical disinfectants that can be mechanically applied have better reduction effects of high-pressure washing.

• 한국재료학회지
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• 제14권6호
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• pp.407-412
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• 2004

Photo decomposition of gas phase benzene by $TiO_2$ thin films chemically deposited on alumina balls were investigated under UV irradiation. Photo decomposition rates were measured in real time during the reaction using a photo ionization detector, which ionizes C-H bonding of benzene molecules and then converts into volatile organic compounds (VOCs) concentrations. From the measuring results, the VOCs concentration increased instantly when IN irradiated because C-H bonds of benzene molecules strongly absorbed on the surface of $TiO_2$ films before the IN irradiation was destroyed by photo decomposition. After that, the VOCs concentration decreased with increasing surface area of $TiO_2$ and reaction time under the IN irradiation. At the optimal conditions for the photo decomposition of gas phase benzene, the reaction rate of the photo decomposition for high concentrations (over 60 ppm) was slow but that of relatively low concentration (under 60 ppm) was fast, due to limited surface area of $TiO_2$ thin films for the reaction. Thus, it is concluded that the photo decomposition rate was mainly affected by the surface area of $TiO_2$ or absorption reaction.

• 한국환경보건학회지
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• 제40권5호
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• pp.397-406
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• 2014

Objectives: Perchloroethylene (PCE) is a volatile chemical widely used as a solvent in the dry-cleaning and textile processing industries. It was evaluated as Group 2 "probably carcinogenic to humans" by the Integrated Risk Information System (IRIS) of the United State Environmental Protection Agency (U.S. EPA) in 2012. In order to provide a scientific basis for establishing risk management measures for chemicals on the national priority substances list, aggregate risk assessment was conducted for PCE, included in the top-10 substances. Methods: We conducted the investigation and monitoring of PCE exposure (e.g., exposure scenario, detection levels, and exposure factors, etc.) and assessed its multi-media (e.g., outdoor air, indoor air, and ground water) exposure risk with a deterministic and probabilistic approach. Results: In human risk assessment (HRA), the level of human exposure was higher in the younger age group. The exposure level through inhalation at home was the highest among the exposure routes. Outdoor air or uptake of drinking water represented less than 1% of total contributions to PCE exposure. These findings suggested that the level of risk was negligible since the Hazard Index (HI) induced by HRA was below one among all age groups, with a maximum HI value of 0.17 when reasonable maximum exposure was applied. Conclusion: In conclusion, it was suggested that despite low exposure risk, further studies are needed considering main sources, including occupational exposure.

• Nuclear Engineering and Technology
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• 제47권6호
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• pp.700-711
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• 2015

Sodium-cooled fast breeder reactors use liquid sodium as a moderator and coolant to transfer heat from the reactor core. The main hazard associated with sodium is its rapid reaction with water. Sodium-water reaction (SWR) takes place when water or vapor leak into the sodium side through a crack on a heat-transfer tube in a steam generator. If the SWR continues for some time, the SWR will damage the surface of the defective area, causing it to enlarge. This self-enlargement of the crack is called "self-wastage phenomena." A stepwise numerical evaluation model of the self-wastage phenomena was devised using a computational code of multicomponent multiphase flow involving a sodium-water chemical reaction: sodiumwater reaction analysis physics of interdisciplinary multiphase flow (SERAPHIM). The temperature of gas mixture and the concentration of NaOH at the surface of the tube wall are obtained by a numerical calculation using SERAPHIM. Averaged thermophysical properties are used to assess the local wastage depth at the tube surface. By reflecting the wastage depth to the computational grid, the self-wastage phenomena are evaluated. A two-dimensional benchmark analysis of an SWAT (Sodium-Water reAction Test rig) experiment is carried out to evaluate the feasibility of the numerical model. Numerical results show that the geometry and scale of enlarged cracks show good agreement with the experimental result. Enlarged cracks appear to taper inward to a significantly smaller opening on the inside of the tube wall. The enlarged outer diameter of the crack is 4.72 mm, which shows good agreement with the experimental data (4.96 mm).

• Environmental Analysis Health and Toxicology
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• 제25권3호
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• pp.223-228
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• 2010

Neocaridina denticulata is a small freshwater shrimp indigenous to Korea. As an indigenous species has long-adapted to particular water environments, the species can be a suitable indicator to assess environmental risks caused by hazard chemicals in the particular site. Thus Neocaridina denticulata, a small freshwater shrimp indigenous to Korea, is worth considering for a test species for such purpose. N. denticulata were exposed to pentachlorophenol sodium salt, sodium azide and potassium dichromate using automatic flow-through system for 96 hours. The 96 hr lethal concentrations ($LC_{50}$) of these chemicals were calculated as $0.53{\pm}0.09\;mg/L$, $2.40{\pm}0.61\;mg/L$ and $1.21{\pm}0.09\;mg/L$ respectively and showed relatively small deviation from repetitive test results. When compared with the toxicity values of other species for each chemical, N. denticulata had moderate or high sensitivity to the toxicity of these chemicals. It can be concluded that N. denticulata is a good test species to evaluate acute toxicity of various hazardous chemicals.

• 한국방재학회:학술대회논문집
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• 한국방재학회 2008년도 정기총회 및 학술발표대회
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• pp.787-790
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• 2008

SWAT(Soil and Water Assesment Tool) 모형은 장기간에 걸친 토양과 토지이용 및 관리 상태에 따라 복잡하게 반응한 대규모 유역의 물과 토사유출 및 농업화학물질로 인해 실제 토지관리가 수환경에 끼치는 영향을 예측하기 위하여 개발되었다. 일반적으로 하천은 유역의 개발 정도에 따라 도시하천과 자연하천으로 나뉘며 도시하천의 경우 도시화가 진행됨에 따라 토지이용상태 및 토지피복상태의 변화로 불투수면적이 증가함에 따라 도시하천의 건천화가 급속도로 진행된다. 본 연구에서는 장기유출모의가 가능한 SWAT 모형을 이용하여 도시하천의 유출량을 모의하고 특히 유역의 규모가 작은 소유역의 SWAT 모형의 적용성을 제시하고자 한다. GIS와 연계한 SWAT 모형을 이용하여 조만강 유역을 모의하였고, 모형의 민감도 분석을 통해 매개변수를 최적화시킴으로서 모델의 신뢰도를 평가하고자 하였다.

• 한국가스학회지
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• 제11권2호통권35호
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• pp.65-70
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• 2007

LP 가스의 폭발현상 및 위험성을 평가하기 위하여, 산소농도변화와 LP 가스의 농도에 따른 혼합가스 조성을 변화시켜 실험을 행하였다. 산소농도 21%에서 LP 가스의 농도가 증가할수록 폭발하한계는 낮아졌으며, 최소산소농도(MOC, Minimum Oxygen Concentration)는 1.0 bar, 1.5 bar, 2.0 bar에서 각각 14.5%, 12.0%, 11.5%로 낮아졌다. 최대폭발압력은 압력이 증가할 경우 $6.46kg/cm^2,\;9.41kg/cm^2,\;13.49kg/cm^2$로 증가하였으며, LP 가스의 초기압력이 클수록 화염의 전파속도가 증가하였다.