• Asian Journal of Atmospheric Environment
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• v.5 no.3
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• pp.164-171
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• 2011

This work focuses on the analysis of bioaerosols in the atmosphere at higher altitudes over Noto Peninsula, Japan. We carried out direct sampling via aircraft, separated cultures, and identified present isolates. Atmospheric bioaerosols at higher altitudes were collected using a Cessna 404 aircraft for an hour at an altitude of 3,500 m over the Noto Peninsula. The aircraft-based direct sampling system was devised to improve upon the system of balloon-based sampling. In order to examine pre-existing microorganism contamination on the surface of the aircraft body, bioaerosol sampling was carried out just before takeoff using the same method as atmospheric sampling. Identification was carried out by a homology search for 16S or 18S rDNA isolate sequences in DNA databases (GenBank). Isolate sampling just before takeoff revealed Stretpomyces sp., Micrococcus sp., and Cladosporium sp. One additional strain, Bacillus sp., was isolated from the sample after bioaerosol collection at high altitude. As the microorganism contamination on the aircraft body before takeoff differed from that while in the air, the presence of additional, higher atmosphere-based microorganisms was confirmed. It was found that Bacillus sp. was floating at an altitude of 3,500 m over Noto Peninsula.

• Proceedings of the Korean Nuclear Society Conference
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• 2001.05a
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• pp.399.1-399
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• 2001

• Proceedings of the Korean Nuclear Society Conference
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• 1999.05a
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• pp.358-358
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• 1999

• Journal of the Korean Geosynthetics Society
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• v.13 no.1
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• pp.63-70
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• 2014

This paper describes the influence of rainfall on contamination at stream around the developed quarry. The investigation results are analyzed to evaluate the relationship rainfall and heavy metals (or water pollution). In the relationship rainfall and heavy metals, the result showed that the heavy metal contaminations are caused by boulder stone, waste residue and stone sludge, which is reacted with the direct contamination source, in the burried layer. It also found that the water flow change of stream according to the rainfall increase affected the large effect to a contamination level of heavy metal. the water pollution was increased by time changed from the rainy season to the dry season. That is, a lot of suspended solids had been discharge from the developed quarry due to rainfall increase, and then pollution level of water increases as the undercurrent of suspended solids is generated in stream due to rainfall decrease. Therefore, it analyzed that continuous causes of heavy metal contamination and water pollution in stream are materials in the burried layer and a discharge of pollution source from the developed quarry due to rainfall.

• Journal of Soil and Groundwater Environment
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• v.23 no.1
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• pp.54-62
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• 2018

This paper is aimed at source tracking of soil heavy metal contamination at a site established by reusing construction wastes. The soil heavy metal concentration at the study site peaked at a depth range of 5-10 m. Column studies were conducted to investigate the possibility of the contamination scenario of infiltration of stormwater carrying heavy metals of ground origin followed by selective heavy metal accumulation at the 5-10 m depth range. Almost all amount of lead, zinc, cadmium, and nickel introduced to the columns each packed with 0-5 m or 5-10 m field soil were accumulated in the column. The very poor heavy metal mobility in spite of the weak association of the heavy metals with the soil (characterized by a sequential extraction procedure) can be attributed to the high pH (10-11) of the construction wastes. From the results, the heavy metal contamination of the subsurface soil by an external heavy metal source was determined to be very unlikely at the study site. The column study applied in the current study is expected to be a useful methodology to present direct evidence of the contaminant source tracking at soil contamination sites.

• Journal of Radiation Protection and Research
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• v.31 no.3
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• pp.123-128
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• 2006

A small radiation detection system is necessary for the direct characterization of alpha/beta-ray contamination inside pipes generated during the decommission of a nuclear facility. In this work, the new type phoswich detector consisting of the ZnS(Ag) and plastic scintillator for ${\alpha}/{\beta}$ simultaneous counting was designed as part of a development of a equipment capable of monitoring radiological contamination inside pipes. The optimum counting conditions in dimensions of scintillator and a detection system were experimentally confirmed and a performance of alpha/beta-ray discrimination was evaluated. As a result, optimum conditions of a detector suitable for monitoring radiological contamination inside pipes and a feasibility of application to pipe-inside were confirmed.

• Proceedings of the KSME Conference
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• 2001.11a
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• pp.507-514
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• 2001

Direct drive servovalve(DDV) is a kind of one-stage valve since the rotary motion of DC motor is directly transferred to the linear motion of valve spool through the link. Since the structure of DDV is simple, it is less expensive, more reliable and offers reduced internal leakage and reduced sensitivity to fluid contamination. However, the flow force effect on the spool motion is significant such that it induces large steady-state error in a step response. If the proportional control gain is increased to reduce the steady-state error, the system becomes unstable. In order to satisfy the system design requirements, the classical controller is designed using the analytical Bode method.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 1996.06c
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• pp.500-510
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• 1996

A Direct injection -mixing total -flow -control sprayer was developed and evaluated . The system provided precise application rates and minimized operator exposure to chemicals as well as providing a possibility for recycling container so f unused chemicals that can causes environmental contamination. Chemicals were metered and injected proportionally to the diluent flow rate to provide constant concentrations. The main diluent flow was varied in response to changes in travel speed. Experimental variables of the sprayer were the control interval, the sensitivity of flow regulating valve, the tolerance of control object and the sensitivity of the injection pump system. The optimal performance of the flow control system was with an average response time of 8.5 sec at an absolute steady state of error of 0.067 L/min (0.8% of flow rate). The average response time of the injection rate was -0.53 sec and the coefficient of variation (CV) of concentration was 3.2%.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.4
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• pp.754-763
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• 2002

Direct drive servovalve(DDV) is a kind of one-stage valve since the rotary motion of DC motor is directly transferred to the linear motion of valve spool through the link. Since the structure of DDV is simple, it is less expensive, more reliable and offers reduced internal leakage and reduced sensitivity to fluid contamination. However, the flow force effect on the spool motion is significant such that it induces large steady-state error in a step response. If the proportional control gain is increased to reduce the steady-state error, the system becomes unstable. In order to satisfy the system design requirements, the classical controller is designed using the analytical Bode method.

• Environmental Engineering Research
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• v.14 no.1
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• pp.53-60
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• 2009

The main objective was to develop and assess a dynamic fate and transport model for lead in air, soil, sediment, water and vegetation. Daejeon was chosen as the study area for its relatively high contamination and emission levels. The model was assessed by comparing model predictions with measured concentrations in multi-media and atmospheric deposition flux. Given a lead concentration in air, the model could predict the concentrations in water and soil within a factor of five. Sensitivity analysis indicated that effective compartment volumes, rain intensity, scavenging ratio, run off, and foliar uptake were critical to accurate model prediction. Important implications include that restriction of air emission may be necessary in the future to protect the soil quality objective as the contamination level in soil is predicted to steadily increase at the present emission level and that direct discharge of lead into the water body was insignificant as compared to atmospheric deposition fluxes. The results strongly indicated that atmospheric emission governs the quality of the whole environment. Use of the model developed in this study would provide quantitative and integrated understanding of the cross-media characteristics and assessment of the relationships of the contamination levels among the multi-media environment.