• Fire Science and Engineering
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• v.29 no.6
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• pp.20-25
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• 2015

In order to examine the explosion risk of 2-ethylhexanoic acid, we experimentally studied the explosion limit, explosion pressure, and rate of increase of the explosion pressure at different oxygen concentrations. The lower explosion limit was 3.2% at a temperature of $100^{\circ}C$, and the oxygen concentration was 40 to 70%. The upper explosion limit was 4.5% and the lower explosion limit was 4.0% at an oxygen concentration of 21%.The maximum explosion pressure of 2-ethylhexanoic acid was 1.4161 MPa at an oxygen concentration of 70%, and the rate of increase of the explosion pressure was 62.692 MPa/s at this concentration.

• Journal of Radiation Protection and Research
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• v.34 no.2
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• pp.77-81
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• 2009

An Area Radiation Monitoring System (ARMS) ionization chamber, which had an 11.8 L active volume, was fabricated and performance-tested at KAERI. Low leakage currents, linearities at low and high dose rates were achieved from performance tests. The correlation coefficients between the ionization currents and the dose rates are 1 at high dose rate and 0.99 at low dose rate. In this study, an integration-type ARMS ionization chamber was tested over a year for an evaluation of its long-term stability at a radioisotope (RI) repository of the Young-gwang nuclear power plant. The standard deviation of dose rate of 1 day data and over a 100-days mean value were 6.2 $\mu$R/h and 2.9 $\mu$R/h, respectively. The fabricated ARMS ionization chamber showed stable performance from the results of the long-term tests. Design and performance characteristics of the fabricated ionization chamber for the ARMS from performance-tests are also addressed.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.7A
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• pp.960-966
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• 2000

It is essential to develop the robust video transmission system over wireless channel, since the effect of the noise and the interference to compressed video may be fatal. In this paper, we have designed turbo code, which is adequate for the transmission of video and analyzed the performance of that. Especially, we have focused the rate compatible punctured turbo(RCPT) code, which has rate compatible(RC) property for unequal error protection(UEP). It has been shown through computer simulation that the turbo code with helical interleaver yields better performance than those with other interleavers when the size of the interleaver is not large.

• Journal of the Korea Safety Management & Science
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• v.26 no.2
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• pp.65-77
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• 2024

This study aims to present a performance based design for apartments through evacuation safety assessment and damage impact assessment due to acrylonitrile leakage. In the evacuation safety evaluation, ASET was analyzed as 25 min or more and 60 min or less when the ventilation rate was once per hour, and RSET was 22.6 min. Evacuation safety is satisfied when the number of ventilation per hour is less than 1, so it is necessary to design the number of ventilation to be 1 or less. In the damage impact assessment, the 0% structural collapse rate due to overpressure was measured to be between 71m and 90m, and the 0% fatality rate due to radiant heat was measured to be between 136m and 353m. Therefore, maintain a safe distance of 353m or more.

• Journal of Applied Biological Chemistry
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• v.61 no.3
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• pp.291-295
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• 2018

Metcalfa pruinosa is a pest causing widespread problems to many crops in Korea. This pest infects fruit crops especially, persimmon and grapes. We tested the possibility of M. pruinosa management using essential oils of Alpina galangal and methylcinnamate which were extracted from A. galangal by steam distillation method. The use of essential oil showed a mortality rate of 10.0 and 23.3% for adults and nymphs, respectively. While the use of methylcinnamate resulted to a mortality rate of 40.0% in adults and 36.6% in nymphs. For its repellent effect, it showed an avoidance rate of 50.0 and 63.3% for adult and nymph respectively. Considering these two results, the extract of A. galangal are shown to have some synergic effect for pest control. The result of this study showed a possibility of M. pruinosa control using essential oil and methylcinnamate from A. galangal.

• Journal of Radiation Protection and Research
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• v.48 no.2
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• pp.59-67
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• 2023

Background: This study aims to reevaluate natural radiation exposure, following up on our previous study conducted in 2019, and to assess the associated risk of lung cancer to the public residing in the gold mining areas of Betare-Oya, east Cameroon, and its vicinity. Materials and Methods: Gamma-ray spectra collected using a 7.62 cm×7.62 cm in NaI(Tl) scintillation spectrometer during a car-borne survey, in situ measurements and laboratory measurements performed in previous studies were used to determine the outdoor absorbed dose rate in air to evaluate the annual external dose inhaled by the public. For determining internal exposure, radon gas concentrations were measured and used to estimate the inhalation dose while considering the inhalation of radon and its decay products. Results and Discussion: The mean value of the laboratory-measured outdoor gamma dose rate was 47 nGy/hr, which agrees with our previous results (44 nGy/hr) recorded through direct measurements (in situ and car-borne survey). The resulting annual external dose (0.29±0.09 mSv/yr) obtained is similar to that of the previous study (0.33±0.03 mSv/yr). The total inhalation dose resulting from radon isotopes and their decay products ranged between 1.96 and 9.63 mSv/yr with an arithmetic mean of 3.95±1.65 mSv/yr. The resulting excess lung cancer risk was estimated; it ranged from 62 to 216 excess deaths per million persons per year (MPY), 81 to 243 excess deaths per MPY, or 135 excess deaths per MPY, based on whether risk factors reported by the U.S. Environmental Protection Agency, United Nations Scientific Committee on the effects of Atomic Radiation, or International Commission on Radiological Protection were used, respectively. These values are more than double the world average values reported by the same agencies. Conclusion: There is an elevated level of risk of lung cancer from indoor radon in locations close to the Betare-Oya gold mining region in east Cameroon. Therefore, educating the public on the harmful effects of radon exposure and considering some remedial actions for protection against radon and its progenies is necessary.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2008.11a
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• pp.310-315
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• 2008

The objective of design for a post flash-over fire is contain the fire and prevent structural collapse, as necessary to meet the performance requirements. In the post flash-over phase of a fire all of the combustible objects in the compartment are burning and the heat release rate is limited either by the fuel surface area or the available air supply. So for the PBD situations, the process of evaluation method for fire phenomena is very important. It is the aim of this study to investigate and analyze the evaluation method of structural fire resistance in Japan.

• ETRI Journal
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• v.25 no.1
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• pp.52-54
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• 2003

We propose an improved algorithm for detecting audio watermarks based on a spread spectrum in the spectral domain. Since the energy of a watermark is much smaller than that of the cover audio data, pre-processing to reduce the effect of the cover data is needed to reliably extract watermarks. We introduce a spectral envelope filter as a pre-process that enhances detecting performance by filtering out the intrinsic spectral character of cover data. The proposed watermarking structure can be easily included in the compression system and can extract watermarks from partially decompressed spectral data. Our experimental results demonstrate that with a bit error rate of around 10 dB against general attacks, the proposed detecting scheme works better than detectors without the spectral filter.

• Journal of the Korean Professional Engineers Association
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• v.43 no.6
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• pp.39-45
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• 2010

Soil plays a huge role in climate change, because even a tiny loss of 0.1% of carbon emitted into the atmosphere from European soils is the equivalent to the carbon emission of 100million extra cars on Europe's roads - an increase of about half of the existing car fleet. Soils contain around twice the amount of carbon in the atmosphere and three times the amount to be found in vegetation. Europe's soils are an enormous carbon reservoir, containing around 75billion tonnes, and poor management can have serious consequences. Soil degradation is accelerating across the EU, with negative effects on human health, ecosystems and climate change - and on economic prosperity and quality of life. Climate change is identified as a common element in many soil threats. Europe's soils urgently need better protection. The current trend of soil degradation needs to be reversed, and soil management practices must be improved if a high rate of soil carbon sequestration is to be achieved.

• Corrosion Science and Technology
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• v.9 no.3
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• pp.137-141
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• 2010

Sodium nitrite is widely used as one of the popular corrosion inhibitors for the protection of ferrous metal in closed cooling water system, such as a diesel engine and a chiller. The optimum treatment conditions are studied through laboratory tests using linear polarization resistance (LPR) technique. Corrosion rate of the carbon steel electrode could be maintained less than $2.5{\times}10^{-3}$ mmpy in the test condition of 500 ppm as ${NO_2}^-$, 200 ppm as $Cl^-$, $70^{\circ}C$ and pH 6.8. The pH control is confirmed not to be an important factor in the protection of carbon steel by sodium nitrite inhibitor. The addition of tolyltriazole was needed for the protection of the copper alloy in the sodium nitrite treatment system.