• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1998.04a
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• pp.124-130
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• 1998

A mathematical model describing gear pump flow degradation in the presense of abrasive particles is presented. The model considers the operating parameters as Sommerfeld number, so that contamination sensitivity test results could be conversed to field application to predict contamination service life. A method to estimate the volumetric efficiency and the contamination level of a pump is proposed by measuring the temperature differences in the fluid. Test results show the validity of the theoretical establishments.

• Proceedings of the Korean Geotechical Society Conference
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• 2006.03a
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• pp.330-337
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• 2006

Resistivity cone penetrometer test (RCPT) can be employed at a relatively low cost for delineation of subsurface contamination in situ, and then be supplemented with a minimum confirmatory sampling and laboratory testing program. While the resistivity measurement have potential to investigate the subsurface contamination, resistivity measurements alone will lead to some degree of ambiguity in the results. In this study, capacitance measurement was incorporated into the RCPT to overcome the ambiguity inherent in electrical resistivity measurements for delineating the subsurface contamination. This study is focused on verifying the applicability of resistivity and capacitance measurements on CPT module to provide information on contaminated subsurface by heavy metal and petroleum hydrocarbon. Laboratory model tests were performed to evaluate the sensitivity of the measured resistivity and relative capacitance on the water content and different types of contaminants. Test results show that simultaneous measurement of electrical resistivity and capacitance can give more reliable information on subsurface contamination.

• Textile Coloration and Finishing
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• v.22 no.1
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• pp.8-13
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• 2010

Needle contamination was investigated using a test rig simulated the knitting points in the knitting machine in relation with the characteristics of knitting yarn such as yarn type and moisture contents. When used open-end yarn compared with combed and carded ring-spun yarns, the needle contamination was significantly increased because of the higher friction between yarn and needle by the fly and other impurities. Also Lower moisture content of the yarns aggravated the needle contamination. In addition knitting yarn breakage was substantially influenced by the higher needle contamination.

• International Journal of Precision Engineering and Manufacturing
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• v.6 no.3
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• pp.51-55
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• 2005

This study addresses the contamination sensitivity test of a typical fuel pump for an automotive vehicle. The objective of the study is to find the contamination sensitivity coefficient of a fuel pump on specific contaminant particle sizes so that an optimal fuel filter could be selected. To achieve the objective, the degradation of discharge flow rate of the fuel pump is measured under the experiments of various contaminants size ranges of ISO test dust up to $80\;{\mu}m$. The fundamental theory of contamination sensitivity is introduced and the contamination sensitivity coefficients are estimated using the experimental data. Maximum contamination sensitivity coefficient of $5\chi\;10^{-6}\;L/min{\cdot}Ea$ is found in the contaminant size range of $40\;{\mu}m\~50\;{\mu}m$. The magnified picture of the surface of vane disc reveals that the abrasive wear is the principal cause of discharge flow rate degradation. Hence, this study reveals that a high efficiency filter for contaminant particles especially in the size range of $30\;{\mu}m\~70\;{\mu}m$ especially should be used to maintain the service life of the fuel filter.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.6
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• pp.102-108
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• 2004

This study addresses the contamination sensitivity test of a typical fuel pump for automotive vehicle. The objective of the study is to find the contamination sensitivity coefficient of fuel pump on specific contaminant particle sizes so that optimal fuel filter could be selected. To achieve the objective, the degradation of discharge flow rate of fuel pump was measured under the experiments of various contaminants size ranges of ISO test dust up to 80${\mu}{\textrm}{m}$. The fundamental theory of contamination sensitivity was introduced and the contamination sensitivity coefficients were estimated using the experimental data. Maximum contamination sensitivity coefficient of $5{\times}10^{-6}$ L/minㆍEa was found on the contaminant size range of 40${\mu}{\textrm}{m}$∼50${\mu}{\textrm}{m}$. The magnified picture of the surface of vane disc revealed that the abrasive wear was the principal cause of discharge flow rate degradation. Hence, this study revealed that high efficiency filter on the contaminant particle size range of 30${\mu}{\textrm}{m}$∼70${\mu}{\textrm}{m}$ especially should be used to maintain the service lift of the fuel filter.

• Journal of Pharmaceutical Investigation
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• v.3 no.4
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• pp.16-27
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• 1973

An investigation was carried out on a basis of the examination with a view to detecting the degree of microbial contamination for the 82 samples collected from the locally-sold liquid preparations. The results obtained are summarized as follows ; 1. Total viable Bacteria(TVB) per ml. in test sample shows min. 0 and Max. $8.0{\times}10^5$. Among the test samples, 2 items of Herb medicines have shown the highest bacterial contamination degree. 2. The number of unsuitable products are 9(11.0%) of the 82 items tested. Comparing with the study of 1971 (18 or 23.4% of 77 items), this fact suggests that the more than 50% decreasing tendency has come from the technical preventive efforts on bacterial contamination. 3. E. coli, Staph. aureus, and Pseudomonas aeruginosa could not be detected with the test sample. 4. The number of confirmable mycotic contamination in the test samples has been revealed as 17 items (20.7%). 5. Chiefly, the causative organisms of the contamination are proved to be bacilli and fungi broadly distributed in nature. 6. Generally, the neutrality of the pH had greatly increased the number of products unsuitable on the specification of TVB. pH >7.0 No. of unsuitable items 0/4 (0.0%) pH 6.0-7.0 No. of unsuitable items 4/9 (44.4%) pH 4.0-6.0 No. of unsuitable items 5/45(11.1%) pH <4.0 No. of unsuitable items 0/24(0.0%) 7. The viability of general bacteria has shown a rather decreasing tendency in time.

• The International Journal of Costume Culture
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• v.2 no.1
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• pp.54-61
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• 1999

The purpose of this research was first to analyse and compare the types of microbes inherent among the unwashed and washed Kupori textiles, and second to investigate whether there is a difference between unwashed and washed Kupori textiles on the susceptibility of contamination by microorganism when exposed to the same microbial environment. Microbial identification procedure and the Shake Flask Test for investigating the effect of exposure to microbial environment were carried out separately. The result of microbial identification procedure indicated that a variety of bacteria and fungi were inherent in both unwashed and washed textiles and that the population of contaminated microorganism became more diverse after washing. The result of Shake Flask Test indicated that given the same exposure condition, the unwashed textiles tend to be more susceptible to bacterial contamination than the washed textiles. The results of the present study supported the current conservation procedures adopted in Korean museums which include washing and humigation procedures before long-term storage or display of exhumed textiles.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.10
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• pp.1461-1470
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• 2012

This paper reports the contamination performance of transmission line porcelain insulators tested under five different contaminant conditions - clean and ESDD (equivalent salt deposit density) level (A, B, C, and D) through measurement of their leakage current under drop of potential method. To estimate the contamination for transmission line porcelain insulators, leakage current waveform and its maximum value were measured under step-up power test. In the clean insulators test, % distortion factors decreased with increasing step-up power, and as the ESDD level increased, some characteristics such as frequency analysis, harmonics and % distortion facotor could be used for contamination diagnosis of the transmission line porcelain insulators.

• Geomechanics and Engineering
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• v.14 no.6
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• pp.563-570
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• 2018

Ballast layer has an important role in vertical stiffness and stability of railway track. In most of the Middle East countries and some of the Asian ones, significant parts of railway lines pass through desert areas where the track (particularly ballast layer) is contaminated with sands. Despite considerable number of derailments reported in the sand contaminated tracks, there is a lack of sufficient studies on the influences of sand contamination on the ballast vertical stiffness as the main indicator of track stability. Addressing this limitation, the effects of sand contamination on the mechanical behavior of ballast were experimentally investigated. For this purpose, laboratory tests (plate load test) on ballast samples with different levels of sand contamination were carried out. The results obtained were analyzed leading to derive mathematical expressions for the strain modulus ($E_V$) as a function of the ballast level of contamination. The $E_V$ was used as an index for evaluation of the load-deformation characteristics and bearing capacity of track substructure. The critical limit of sand contamination, after which the $E_V$ of the ballast reduces drastically, was obtained. It was shown that the obtained research results improve the current track maintenance approach by providing key guides for the optimization of ballast maintenance planning (the timing of ballast cleaning or renewal).

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2003.09a
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• pp.536-539
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• 2003

This study area has been contaminated by oils. To identify contaminated ranges and to assess the possibility of contamination dispersion, monitoring wells were installed and slug test, field soil permeability test, automatic or manual measurement of groundwater table, and groundwater quality analyses in field and laboratory were performed. In addition, a groundwater modeling program was used to assess the possibility of oil contamination dispersion, based on field data and groundwater quality data. The results showed that concentration of oil contaminants in groundwater have been decreased by dispersion and adsorption.