• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 1999.10a
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• pp.34-38
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• 1999

This paper investigated remediation options for contaminated sediments with heavy metals. Twenty three sediment samples were taken from three different depths of 0.5m, 1.5m and 2.5m. The concentration of Heavy metals Cu, Pb, and Hg were measured. The concentration of copper far exceeded the Sediment Quality Guideline in U.S.A and Interim Sediment Quality Guidelines in Canada. Therefore, remediation of the sediments is requried to protect the benthos. Two remediation options were suggested : dredging of the organic sediments as deep as about 85cm followed by surface covers with clean soil, and in-situ stabilization of tile sediments using lime or cement followed by surface cover with clean soil.

• Journal of Korean Society for Atmospheric Environment
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• v.18 no.6
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• pp.475-485
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• 2002

An analytical method was investigated for the meaiiurement of polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) concentrations in air samples. Procedures required for column chromatographic clean up. silicagel (stage I) and gel permeation chromatography (stage II), were discussed. Identification and quantification of PCBs and OCPs were performed using a combination of gas chromatography/mass spectrometry/ selected ion monitoring. Recovery tests calculated from six samples are 68∼137% for PCBs and 58∼130% for OCPs except for endrin aldehyde. Instrumental detection limits determined for the PCBs and OCPs varied from 0.05 to 0.18 pg/m3 and from 0.71 to 16.82 pg/㎥, respectively. The method has been applied to the analysis of air samples collected at Ansung city, Kyonggi province, Korea. This method may serve as a screening protocol for the simultaneous determination of PCBs and OCPs in air.

• MALSORI
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• no.63
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• pp.153-170
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• 2007

It is well known that when there is an acoustic mismatch between the speech obtained during training and testing, the accuracy of speaker verification systems drastically deteriorates. This paper presents the use of MFCCs' histogram enhancement technique in order to improve the robustness of a speaker verification system. The technique transforms the features extracted from speech within an utterance such that their statistics conform to reference distributions. The reference distributions proposed in this paper are uniform distribution and beta distribution. The transformation modifies the contrast of MFCCs' histogram so that the performance of a speaker verification system is improved both in the clean training and testing environment and in the clean training and noisy testing environment.

• Proceedings of the KSR Conference
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• 2009.05a
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• pp.919-929
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• 2009

2008, Seoulmetro transports an average of 3,952,000 passengers every day with a 0.8% increase of the daily ridership compared to last year.(Korean Economics '09.01.21) Seoul subway systems ridden by a considerable number of Seoul citizens place their top priority on swiftness, safety and clean underground air quality so as to meet the customer satisfaction. One of the most important problems is to eliminate minute dust(PM10) among the pollutants such as the gas attributable to air pollution and floating particulate matter defined by the ordinance of the Ministry of Environment. Seoulmetro install and operate many kinds of air filtration facilities, however we've launched a research on "Standardization Plan on Underground Air Filtration Facility" for the installation and improvement of optimum standardized air filtration system. As a preliminary study, we're going to consider ventilation system and air filter to supply filtered metropolitan outdoor air aimed at ensuring clean underground environment.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.221-222
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• 2006

This paper describes a Plasma Assisted Debinding and Sintering (PADS) equipment, which has been designed to process Metal Injection Molded (MIM) components. The use of a hybrid system combining a glow discharge with a conventional heating system makes debinding and sintering of MIM components, in the same heating cycle, a feasible industrial process. Characteristics as density, carbon content and mechanical properties are similar to traditionally processed MIM materials. The reduction of energy and gas consumption and shorter lead-times are economic advantages of PADS system. The clean environment of PADS is also an ecological advantage.

• Environmental and Resource Economics Review
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• v.21 no.3
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• pp.627-681
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• 2012

This paper starts with a model of monopolistic competition and endogenous growth, and it adds pollution as an input to production. Then I adopt environmental quality as a renewable resource used in production. I show that increasing returns due to specialization of clean activities as inputs can help lead to sustainable growth with no harm to environmental quality. I also compare and evaluate alternative policy combinations (i.e. taxes +subsidies) that correct two distortions from pollution and monopolistic competition. Finally, I find that, if the productivity of environment in final good production is not sufficiently enough, the number of clean goods tends to increase with more environmental concerns.

• Clean Technology
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• v.2 no.2
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• pp.165-175
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• 1996

Cutting fluids in machining process are one of the parameters which have serious effects on the environment. A simple method to accomplish the environmentally clean process is to evaluate the effects of cutting fluids and select one which has the least environmental load. In this research, a process planning to select the best cutting fluid is suggested considering both machinability and environmental effects. The selection criteria and evaluation method named AHP are introduced. The planning process is illustrated with drilling characterized as a heavy-duty and low-speed process. Five standard fluids are compared with respect to five environmental attributes. Compounded cutting oils are superior to water-soluble oils in both machinability and environmental effects.

• Proceedings of the SAREK Conference
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• 2008.11a
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• pp.452-457
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• 2008

We performed a study on the contaminant transfer in a clean space for the location of product and fan filter unit using computational fluid dynamics analysis. To simplify the real product moving process, three different non-moving cases regrading the locations of product were selected: no product, at the lower side, and at the upper and lower sides. And to investigate the characteristics of the contaminant transfer, the arrangement of fan filter units was varied. Local mean air-age and contaminant distribution were used as evaluation indices. From the results, the contaminant transfer to the product was the most when the products were simultaneously located at the upper and lower sides. And the contaminant was easily exhausted regardless of the location of product when the fan filter units were properly arranged at the top side of the clean space.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.21 no.5
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• pp.273-281
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• 2009

In recent semiconductor manufacturing clean rooms, the energy consumption of outdoor air conditioning systems represents about 45% of the total air conditioning load required to maintain a clean room environment. Meanwhile, there is a large amount of exhaust air from a clean room. From an energy conservation point of view, heat recovery from the exhaust air is therefore useful for reducing the outdoor air conditioning load for a clean room. In the present work, an energy-efficient outdoor air conditioning system was proposed to reduce the outdoor air conditioning load by utilizing an air washer to recover heat from the exhaust air. The proposed outdoor air conditioning system consisted mainly of a preheating coil, an air washer, two stage cooling coils, a reheating coil, a humidifier and two heat recovery cooling coils inserted into the air washer and connected to a wet scrubber. It was shown from the lab-scale experiment with outdoor air flow of $1,000\;m^3/h$ that the proposed system was more energy-efficient for the summer and winter operations than an outdoor air conditioning system with a simple air washer.

• Proceedings of the Korean Environmental Health Society Conference
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• 2006.06a
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• pp.111-122
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• 2006