• Journal of the Institute of Convergence Signal Processing
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• v.4 no.1
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• pp.15-26
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• 2003

Ultrasonic inspection methods are widely used for detecting flaws in materials. The signal analysis step plays a crucial part in the data interpretation process. A number of signal processing methods have been proposed to classify ultrasonic flaw signals. One of the more popular methods involves the extraction of an appropriate set of features followed by the use of a neural network for the classification of the signals in the feature space. This paper describes an alternative approach which uses the least mean square (LMS) method and expectation maximization (EM) algorithm with the model based deconvolution which is employed for classifying nondestructive evaluation (NDE) signals from steam generator tubes in a nuclear power plant. The signals due to cracks and deposits are not significantly different. These signals must be discriminated to prevent from happening a huge disaster such as contamination of water or explosion. A model based deconvolution has been described to facilitate comparison of classification results. The method uses the space alternating generalized expectation maximization (SAGE) algorithm In conjunction with the Newton-Raphson method which uses the Hessian parameter resulting in fast convergence to estimate the time of flight and the distance between the tube wall and the ultrasonic sensor Results using these schemes for the classification of ultrasonic signals from cracks and deposits within steam generator tubes are presented and showed a reasonable performances.

• Economic and Environmental Geology
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• v.29 no.1
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• pp.45-55
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• 1996

Although the Dongjin Au-Ag-Cu mine had been abandoned since about forty years ago, the results of this study on the dispersion patterns and contamination level of heavy metals in the hydrologic system flowing via the waste rump show that the environmental impacts from the mine wastes are still significant. The stream water in the vicinity of the waste rump is severely acidified (pH 3.8 to 4.4) and highly enriched in various dissolved heavy metals. The heavy metal contents of the stream water and stream sediments are systematically attenuated with increasing distance from the mine area. However, it is worth to note that continuous attenuation of heavy metal contents in both media were reenriched in downstream area more than 800 m apart from the mine because it can be acted as a secondary source of heavy metal pollution. The heavy metals, especially Cd, Cu and Zn of polluted downstream sediments mainly occur in Fe-Mn oxides and organic materials, which indicates that these elements are the main pollutants from the waste rump of the Dongjin mine. The heavy metal contents of crops, such as sesame, perilla, red Pepper and brown rice, collected from the polluted farm land in the downstream area are lower than those of land plants from stream sides, but significantly higher in Cd, Cr, Cu and Zn than those from the unpolluted farm land. Especially, almost all of the crops in polluted farm land have been severly contaminated by Cd (>0.4 ppm). On the other hand, the heavy metal contents of the crops collected from refreshed farm land by means of a soil addition method shows significantly lowered level comparing with those of polluted area, which indicates that a soil addition method was effective for the refreshment of polluted farm land by toxic metallic pollutants. Wormwoods from this area showed very high contents in a11 the heavy metals even in unpolluted area (Cd > 1 ppm, Cr > 1 ppm, Cu > 11 ppm, Pb> 4 ppm, Zn > 55 ppm), indicating that a special caution must be payed when one takes ingest them.

• Journal of Food Hygiene and Safety
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• v.24 no.1
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• pp.86-93
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• 2009

This study was conducted to determine microbiological assessment on edible ices, which is one of mandatory items for HACCP application, and to provide basic scientific data for the improvement of HACCP system. In HACCP applied edible ice companies, the contamination levels of total counts, yeast and mold, and coliform from raw materials, mixed samples before sterilization, mixed samples after sterilization, and final products of edible ices were lower than those of non-HACCP applied edible ice companies. Foodborne pathogens, such as L. monocytogenes, Salmonella spp., B. cereus, B. aureus, Y. enterocolitica were not detected in all samples of edible ices from HACCP applied edible ice companies, but S. aureus was isolated1 from 1 raw material, 1 mixed samples before sterilization and 1 final product of edible ices from non-HACCP applied edible ice companies, respectively.

• Journal of the Korean Society for Nondestructive Testing
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• v.25 no.1
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• pp.27-35
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• 2005

Ultrasonic inspection methods are widely used for detecting flaws in materials. The signal analysis step plays a crucial part in the data interpretation process. A number of signal processing methods have been proposed to classify ultrasonic flaw signals. One of the more popular methods involves the extraction of an appropriate set of features followed by the use of a neural network for the classification of the signals in the feature spare. This paper describes an alternative approach which uses the least mean square (LMS) method and exportation maximization (EM) algorithm with the model based deconvolution which is employed for classifying nondestructive evaluation (NDE) signals from steam generator tubes in a nuclear power plant. The signals due to cracks and deposits are not significantly different. These signals must be discriminated to prevent from happening a huge disaster such as contamination of water or explosion. A model based deconvolution has been described to facilitate comparison of classification results. The method uses the space alternating generalized expectation maximiBation (SAGE) algorithm ill conjunction with the Newton-Raphson method which uses the Hessian parameter resulting in fast convergence to estimate the time of flight and the distance between the tube wall and the ultrasonic sensor. Results using these schemes for the classification of ultrasonic signals from cracks and deposits within steam generator tubes are presented and showed a reasonable performances.

• Journal of Food Hygiene and Safety
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• v.35 no.1
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• pp.31-36
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• 2020

To ensure food safety of berries from radioactive contamination, radioactivity monitoring was conducted with a total 258 samples of the berries and processed berry products distributed in Gyeonggi-do, South Korea, from 2016 to 2018. The concentration of artificial radionuclides, ¹³¹I, ¹³⁴Cs and ¹³⁷Cs, was analyzed using gamma-ray spectrometry. ¹³¹I and ¹³⁴Cs were not detected above the MDA (Minimum Detectable Activity) value from any of the samples. However, the range of radioactivity concentration of ¹³⁷Cs was 0.69-808.90 Bq/kg in 39 cases of berries. ¹³⁷Cs was detected at 0.70-3.29 Bq/kg from 6 cases of domestic berries, which were manufactured from imported raw materials. Among 33 cases of imported berries, ¹³⁷Cs was detected at 0.69-808.90 Bq/kg. The concentrations of ¹³⁷Cs in 1 case of blueberry powder product (808.90 Bq/kg) and 2 cases of lingonberry powder products (103.93, 188.46 Bq/kg) exceed domestic maximum radioactivity limits, and these were detected in the berries from Poland. These results suggest that monitoring system for imported berries and processed berry products should be continuously intensified to secure food safety.

• Journal of Marine Bioscience and Biotechnology
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• v.2 no.2
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• pp.102-107
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• 2007

Environmental contamination becomes a great public concern as our society gets industrialized rapidly. The present study examine the role of chitosan in a effort to intervene the environmental pollutant-induced toxicity. PCB-induced neurotoxicity with respect to the PKC signaling was examined. Since the developing neuron is particularly sensitive to PCB-induced neurotoxicity, we isolated cerebellar granule cells derived from 7-day old SD rats and grew cells in culture for additional 7 days to mimic PND-14 conditions. PCB showed the alteration of PKC signaling pathway. The alteration was structure-dependent. Mono-ortho-substituted congeners at a high dose showed a significant increase of total PKC activity at [$^3H$]PDBu binding assay, indicating that mono-ortho-substituted congeners are more neuroactive than non-ortho-substituted congeners in neuronal cells. PKC isoforms were immunoblotted with respective monoclonal antibodies. PKC-beta II and -epsilon were activated with mono-ortho-substituted congeners exposure. The result suggests that the position with ortho has a higher potential of altering the signaling pathway. Alteration of PKC was blocked with treatment of high molecular weight of chitosan. The study demonstrated that the ortho position in PCBs are important in assessing the structure-activity relationship. The results suggest a potential use of marine bioactive materials as a means of nutritional intervention to prevent the harmful effects of pollutant-derived toxicity.

• Korean Journal of Construction Engineering and Management
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• v.11 no.4
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• pp.100-108
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• 2010

With the rapid economic growth and improvement of living conditions in Korea, rebuilding and redevelopment of existing houses has also been rapidly increasing. As a result, considerable construction and demolition wastes have been produced. Demolition wastes, however, must be given special attention because of the various harmful substances in them. The construction waste has been produced most at demolition phase, but the research into that area has not being to make nearly within the country. The aim of this study was to evaluate and compare the contamination figures of the heavy metals and toxin organic substances in the soil and water caused by flying ashes generated and eventually accumulated in building demolition works. AB a result. most of the pollution levels were not worrisome, but some were increased after the demolition with the water used to prevent the dusty air and in the target buildings. However in the vicinity of the demolition sites with explosives there was no report of study in water and soil pollutions, so to minimize pollutions we need to make plans to select the harmful substance in the first place. Thus, this research is expected to be the important materials for future research into the construction waste area.

• Journal of Periodontal and Implant Science
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• v.31 no.4
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• pp.749-763
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• 2001

Osseointegrated titanium implants have become an integral therapy for the replacement of teeth lost. For dental implant materials, titanium, hydroxyapatite and alumina oxide have been used, which of them, titanium implants are in wide use today. Titanium is known for its high corrosion resistance and biocompatability, because of the high stability of oxide layer mainly consists of $TiO_2$. With the development of peri-implantitis, the implant surface is changed in surface topography and element composition. None of the treatments for cleaning and detoxification of implant surface is efficient to remove surface contamination from contaminated titanium implants to such extent that the original surface elemental composition. In this sights, the purpose of this study was to evaluate rough surface titanium implants by means of scanning electron microscopy(SEM) and X-ray photoelectron spectroscopy(XPS) with respect to surface appearance and surface elemental composition. Moreover, it was also the aim to get the base for treatments of peri-implantitis. For the SEM and XPS study, rough surface titanium models were fabricated for control group. Six experimental groups were evaluated: 1) long-time room exposure, 2 ) air-powder abrasive cleaning for 1min, 3) burnishing in citric acid(pH1) for 1min, 4) burnishing in citric acid for 3min, 5) burnishing in tetracycline for 1min, 6) burnishing in tetracycline for 3min. All experimental treatments were followed by 1min of rinsing with distilled water. The results were as follows: 1. SEM observations of all experimental groups showed that any changes in surface topography were not detected when compared with control group. (750 X magnification) 2. XPS analysis showed that in all experimental groups, titanium and oxygen were increased and carbon was decreased, when compared with control group. 3. XPS analysis showed that the level of titanium, oxygen and carbon in the experimental group 3(citric acid treatment for 1min, followed by 1min of distilled water irrigation) reached to the level of control group. 4. XPS analysis showed that significant differences were not detected between the experimental group 1 and the other experimental groups except of experimental group 3. The Ti. level of experimental group 2, airpowder abrasive treatment for lmin followed by 1min of saline irrigation, was lower than the Ti. level of tetracycline treated groups, experimental group 5 and 6. From the result of this study, it may be concluded that the 1min of citric acid treatment followed by same time of rinsing with distilled water gave the best results from elemental points of view, and can be used safely to treat peri-implantitis.

• Journal of Radiation Protection and Research
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• v.42 no.2
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• pp.83-90
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• 2017

Background: Different cases exist in the measurement of thyroid radiobioassays owing to the individual characteristics of the subjects, especially the potential variation in the counting efficiency. An In situ Object Counting System (ISOCS) was developed to perform an efficiency calibration based on the Monte Carlo calculation, as an alternative to conventional calibration methods. The purpose of this study is to evaluate the applicability of ISOCS to thyroid radiobioassays by comparison with a conventional thyroid monitoring system. Materials and Methods: The efficiency calibration of a portable high-purity germanium (HPGe) detector was performed using ISOCS software. In contrast, the conventional efficiency calibration, which needed a radioactive material, was applied to a scintillator-based thyroid monitor. Four radioiodine samples that contained $^{125}I$ and $^{131}I$ in both aqueous solution and gel forms were measured to evaluate radioactivity in the thyroid. ANSI/HPS N13.30 performance criteria, which included the relative bias, relative precision, and root-mean-squared error, were applied to evaluate the performance of the measurement system. Results and Discussion: The portable HPGe detector could measure both radioiodines with ISOCS but the thyroid monitor could not measure $^{125}I$ because of the limited energy resolution of the NaI(Tl) scintillator. The $^{131}I$ results from both detectors agreed to within 5% with the certified results. Moreover, the $^{125}I$ results from the portable HPGe detector agreed to within 10% with the certified results. All measurement results complied with the ANSI/HPS N13.30 performance criteria. Conclusion: The results of the intercomparison program indicated the feasibility of applying ISOCS software to direct thyroid radiobioassays. The portable HPGe detector with ISOCS software can provide the convenience of efficiency calibration and higher energy resolution for identifying photopeaks, compared with a conventional thyroid monitor with a NaI(Tl) scintillator. The application of ISOCS software in a radiation emergency can improve the response in terms of internal contamination monitoring.

• Applied Microscopy
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• v.2 no.1
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• pp.39-46
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• 1972

There are many kinds of microscopes suitable for general studies; optical microscopes(OM), conventional transmission electron microscopes (TEM), and scanning electron microscopes(SEM). The optical microscopes and the conventional transmission electron microscopes are very familiar. The images of these microscopes are directly formed on an image plane with one or more image forming lenses. On the other hand, the image of the scanning electron microscope is formed on a fluorescent screen of a cathode ray tube using a scanning system similar to television technique. In this paper, the features and some applications of the scanning electron microscope will be discussed briefly. The recently available scanning electron microscope, combining a resolution of about $200{\AA}$ with great depth of field, is favorable when compared to the replica technique. It avoids the problem of specimen damage and the introduction of artifacts. In addition, it permits the examination of many samples that can not be replicated, and provides a broader range of information. The scanning electron microscope has found application in diverse fields of study including biology, chemistry, materials science, semiconductor technology, and many others. In scanning electron microscopy, the secondary electron method. the backscattererd electron method, and the electromotive force method are most widely used, and the transmitted electron method will become more useful. Change-over of magnification can be easily done by controlling the scanning width of the electron probe. It is possible. to continuously vary the magnification over the range from 100 times to 1.00,000 times without readjustment of focusing. Conclusion: With the development of a scanning. electron microscope, it is now possible to observe almost all-information produced through interactions between substances and electrons in the form of image. When the probe is properly focused on the specimen, changing magnification of specimen orientation does not require any change in focus. This is quite different from the conventional transmission electron microscope. It is worthwhile to note that the typical probe currents of $10^{-10}$ to $10^{-12}\;{\AA}$ are for below the $10^{-5}$ to $10^{-7}\;{\AA}$ of a conventional. transmission microscope. This reduces specimen contamination and specimen damage due to heatings. Outstanding features of the scanning electron microscope include the 'stereoscopic observation of a bulky or fiber specimen in high resolution' and 'observation of potential distribution and electromotive force in semiconductor devices'.