• Proceedings of the KSME Conference
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• 2000.04b
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• pp.865-870
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• 2000

The flow and the moisture contamination of the dry room in the manufacturing process of lithium ion battery are analyzed numerically by finite volume method. Standard ${\kappa}-{\varepsilon}$ turbulent model widely applied in predicting turbulent flow is adopted in this study. Moisture contamination and distribution are studied by assumption of two cases; one-point generation and uniform generation throughout the room. To evaluate ventilation efficiency on moisture contamination, scales of ventilation efficiency are introduced. From these analyses, moisture contamination is strongly dependent on the flow field and the radius of moisture contamination can be reduced by closing a part of outlets in a dry room.

• Journal of Food Hygiene and Safety
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• v.35 no.1
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• pp.60-67
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• 2020

This study determined the microbial contamination levels of hot pepper at harvest, sorting, and distribution stages to suggest a way of reducing the microbial contamination of hot peppers by changing work gloves used throughout these processes. According to the monitoring results, the contamination levels of total aerobic bacteria (TAB) were found in the following order: soil (5.3±0.9 log CFU/g), hot pepper (4.2±0.9 log CFU/g), gloves (4.2±0.6 log CFU/g), baskets (4.1±0.7 log CFU/ g), clippers (3.9±0.6 log CFU/ g) and water (3.2±1.1 log CFU/g) at harvest stage. The contamination level of coliforms were found in the following order: soil (2.2±0.9 log CFU/g), hot pepper (2.2±0.3 log CFU/g), gloves (2.1±0.6 log CFU/g), clippers (2.0±0.21 log CFU/ g) and baskets (1.9±1.1 log CFU/ g) at harvest stage. TAB on hot pepper at the harvest stage was reduced from 4.2±0.9 log CFU/g to cold storage 3.8±0.2 log CFU/g and room temperature storage 2.6±0.3 log CFU/g, respectively. By the replacement of work gloves and lower distribution temperature, TAB levels of the peppers were significantly reduced compared to those without replacement and distributed at room temperature. In addition, the utilization of plasma was effective on reducing microbial contamination of hot pepper. These results demonstrated that appropriate replacement of gloves at the harvest stages, using plasma in the distribution stage, and refrigerated distribution conditions, which are simple and easy to practice in the field, are effective to reduce microbial contamination on hot peppers.

• Tribology and Lubricants
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• v.33 no.6
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• pp.263-268
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• 2017

The significance of maintaining the soil environment is gradually increasing owing to soil and underground water contamination by petroleum leak accidents. However, the purification of soil is an expensive and more time-consuming process than the purification of contaminated water and air. Moreover, determining the source and people responsible for soil pollution gets often embroiled in legal conflicts, further delaying the cleanup process of the contaminate site. Generally, TPH (total petroleum hydrocarbon) pattern analysis is used to determine the petroleum species and polluter responsible for soil contamination. However, this process has limited application for petroleum products with a similar TPH pattern. In this study, we analyze the TPH pattern and specific sectional ratio (${\sim}C_{10}$, $C_{10}-C_{12}$, $C_{12}-C_{36}$, and $C_{36}{\sim}$) of various domestic petroleum products to identify the petroleum product responsible for soil contamination. Also, we perform BTEX (benzene, toluene, ethyl benzene, xylene) quantitative analysis and determine B:T:E:X ratio using GC-MS. The results show that gasoline grade 1 and 2 have a similar TPH pattern but different BTEX values and ratios. This means that BTEX analysis can be used as a new method to purify soil pollution. This complementary TPH and BTEX method proposed in this study can be used to identify the petroleum species and polluters present in the contaminated soil.

• Journal of Soil and Groundwater Environment
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• v.22 no.1
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• pp.13-17
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• 2017

Over 30% of domestic soil contamination has occurred via petroleum products and complex oil. Moreover, contamination by complex oil is more intense than it is by a single petroleum product species. In this study, we analyzed sectional TPH (total petroleum hydrocarbon) pattern and sectional ratio of current domestically distributed petroleum products, such as kerosene, diesel, bunker C, and lubricant and complex oils, to determine pollution characteristics of the soil. In the TPH pattern, kerosene, which is a light distillate, had an early retention time, and lubricant oil, which is a heavy distillate, had a late retention time in the gas chromatogram. In addition, we obtained a complexly contaminated soil via diesel and lubricant oil from the Navy and inspected it for its ratio of complex oil species. The inspection results showed that this soil was contaminated with 85% diesel and 15% lubricant oil. The method developed in this study could be used to determine complex petroleum sources and ratios at sites with accidentally contaminated soil.

• Journal of Pharmaceutical Investigation
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• v.21 no.3
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• pp.155-160
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• 1991

Particulate is the foreign insoluble material in injectable solution inadvertently present in a given product. Considerable efforts have been made to avoid or minimize particulate contamination by pharmaceutical manufacturers during the production of parenteral products. Particulate contamination of the parenteral products can occur mainly during the opening (cutting) the container immediately before clinical use. In this study, particulate contamination generated during the opening process of ampoules (conventional type, 1-point and color-break ampoules) was compared with that of a prefilled injectable container (prefilled syringe). The particles were examined under a microscope after filtration of the total fluids in the containers. Particles having wide range of size distribution were found from all the ampoules tested. The contamination from the I-point ampoule and colorbreak ampoule was much less than from the conventional ampoule. Glass particles generated by cutting the glass-made ampoules seemed a principal source of the particulate contamination. The glass-partiaulte contamination could be improved substantially by replacing the ampoule containers with the prefilled syringe. Prefilled syringe, which can be used without any cutting process. did not generate particulates during the use. Therefore, it was concluded that prefilled syringe is most preferable container for the small volume parenteral (SVP) fluids in terms of particulate contamination.

• Nuclear Engineering and Technology
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• v.54 no.5
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• pp.1606-1615
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• 2022

For investigating whether the MARSSIM nonparametric test has sufficient statistical power when a site has a specific contamination distribution before conducting a final status survey (FSS), a novel approach was proposed to predict the release probability of the site. Five distributions were assumed: lognormal distribution, normal distribution, maximum extreme value distribution, minimum extreme value distribution, and uniform distribution. Hypothetical radioactivity populations were generated for each distribution, and Sign tests were performed to predict the release probabilities after extracting samples using Monte Carlo simulations. The designed Type I error (0.01, 0.05, and 0.1) was always satisfied for all distributions, while the designed Type II error (0.01, 0.05, and 0.1) was not always met for the uniform, maximum extreme value, and lognormal distributions. Through detailed analyses for lognormal and normal distributions which are often found for contaminants in actual environmental or soil samples, it was found that a greater statistical power was obtained from survey units with normal distribution than with lognormal distribution. This study is expected to contribute to achieving the designed decision error when the contamination distribution of a survey unit is identified, by predicting whether the survey unit passes the statistical test before undertaking the FSS according to MARSSIM.

• Journal of Environmental Health Sciences
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• v.45 no.5
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• pp.487-496
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• 2019

Objective: The purpose of this study was to create soil contamination maps using QGIS (Quantum Geographic Information System) and suggest selection methods for soil pollution sources for preferential investigation in a soil contamination survey. Method: Data from soil contamination surveys over five years in Gyeonggi-do Province, South Korea (2013-2017) were used for making soil contamination maps and analyzing the density of survey points. By analyzing points exceeding the concern level of soil contamination, soil pollutant sources for priority management were identified and selection methods for preferred survey points were suggested through a study of the model area. Results: A soil contamination survey was conducted at 1,478 points over five years, with the largest number of surveys conducted in industrial complex and factory areas. Soil contamination maps for copper, zinc, nickel, lead, arsenic, fluoride, and total petroleum hydrocarbons were made, and most of the survey points were found to be below concern level 1 for soil contamination. The density of the survey points is similar to that of densely populated areas and factory areas. The analysis results of points exceeding the criteria showed that soil pollutant sources for priority management were areas where ore and scrap metals were used and stored, traffic-related facilities areas, industrial complex and factory areas, and areas associated with waste and recycling. According to the study of the model area, the preferred survey points were traffic-related facilities with 15 years or more since their construction and factories with a score of 10 or more for soil contamination risk. Conclusion: Soil contamination surveys should use GIS for even regional distribution of survey points and for the effective selection of preferred survey points. This study may be used as guidelines to select points for a soil contamination survey.

• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.665-668
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• 2006

Sodium is a serious contamination in LTPS TFT process. It causes the abnormal characteristics of TFT in operation. Contaminated areas can be seen in SEM images, but EDX measurements do not have adequate sensitivity to confirm the presence of superficial sodium residues. We employed SIMS as a fast analysis method to map the non-uniform distribution of sodium on the surface. SIMS can also indicate the thickness of the contamination.

• Nuclear Engineering and Technology
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• v.53 no.5
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• pp.1664-1675
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• 2021

In order to verify the statistical performance of the nonparametric tests used in the MARSSIM approach, all plausible contamination distribution types that can be encountered in a survey area should be investigated. As the first of such investigations, this study aims to perform the verification for normal distribution of the contamination in a survey area by simulating the collection of random samples from it through the Monte Carlo simulation. The results of the simulations conducted for a total of 81 simulation cases showed that Sign test and WRS test both exhibited an excellent statistical performance: 100% for the former and 98.8% for the latter. Therefore, in final status surveys of the MARSSIM approach, a high statistical performance can be expected in applying the nonparametric hypothesis tests to survey areas whose net contamination can be assumed to be normally distributed.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.29 no.7 s.238
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• pp.795-804
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• 2005

As the flying height of a slider in a hard disk drive decreases, the slider and disk are more likely to come in contact and generate contamination particles. Since particle contamination can cause serious problems including thermal asperity, it must be prevented to increase storage capacity. When particles are generated in a HDD, particles can be charged and have a few number of elementary charges. In this paper, the size distribution of particles and electrical current due to particle according to the disk rotational speed were measured. Also, the average number of elementary charges was calculated from experimental data. SEM images of particles were obtained by using a particle sampler designed in our laboratory.