• Nuclear Engineering and Technology
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• v.25 no.1
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• pp.37-50
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• 1993

To evaluate the sequence of event and the Thermohydraulic behavior during total loss of feedwater accident and recovery procedure, a RELAP5/MOD3 calculation is performed and compared with the LOFT L9-l/L3-3 experiment. Also, the predictability of the code for the major Thermohydraulic phenomena following the accident is assessed. As a result, it is found that a pressure control using the spray until the time the water level reaches the top of the pressurizer, an overpressure protection by pressurizer PORV, a recovery of the secondary heat removal capability by refilling steam generator, and an effective cooldown by the continued natural circulation can be performed without core uncovery. It is also found that the plant-specific evaluation is necessary to confirm the effectiveness of the current symptom-oriented emergency operating procedure, especially in an overpressure protection performance and steam generator recovery performance.

• Korean Journal of Microbiology
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• v.33 no.2
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• pp.157-162
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• 1997

Recently the bioremediation technology has been widely used to recover the oil contaminated environments The application of bioremediation agents to oil polluted environments became common and thus many kinds of commercial products were imported into domestic market. In Korea, howcver. the standardization of bioremediation products quality is not yet established and results of efficacy test .ire scarce. In this study five oil spill bioremediation commercial products including microbial inoculants and en'cyme agents are tested for the oil degradation rate. From the results most products shows the strong oil emulsifying phenomena due to the contained chemical oil dispersant and the low oil degradation rate. Product D inhibited the oil degradability of microorganisms even in the natural sea water. From these results it could be concluded that in the near future the laboratory protocol and standardization of products quality for bioremediarion agents should be prepared to activate the effective application of bioremediation technology in Korea.

• Korean Journal of Microbiology
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• v.33 no.2
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• pp.125-130
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• 1997

Microbial reduction of hexava1ent(VI) to trivalent(lII) chromium is regarded as one of the mechanisms that confers resistance to bacteria. In order to verify this hypothesis, we compared Cr(VI) resistance with Cr(VI) reduction among 20 phenotypically distinct environmental isolates from Cr-contaminated and uncontaminated soils. With glucose as an electron donor, Cr(VI) reduction by washed cell suspensions ranged from 0.014 to 0.305 mM Cr(VI) reduced $h^1$. Cr(VI) resistance of the isolates were measured by growth inhibitions on a liquid medium containing 2 mM Cr(VI) based on their decrease of $A_{630}1$ as compared to the controls without Cr(VI). The isolates had a broad range of resistance from no inhibition to 93.4% inhibition of their growth. Upon correlation analysis, there was no significant relationship between those two phenomena. At a population level, a comparison of % resistant viable counts among the Cr-contaminated and uncontaminated soils showed 19.1 % and 0.4% of their total viable counts, respectively. The difference of % resistance between two site,. strongly suggested that the Cr(VI) present in the soils influences natural selection for resistant phenotypes. However, it is unlikely that the Cr(VI) resistance is dependent solely on the reduction as judged by the correlation analysis.

• Journal of Korean Elementary Science Education
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• v.24 no.1
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• pp.1-8
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• 2005

This study was designed to compare the understanding of ordinary elementary school students and scientifically gifted students about scientists. 473 fourth, fifth, and sixth graders in ordinary elementary schools and 40 students attending scientific educational institutions for the gifted were studied with the help of questionnaires and interviews. The survey showed that there were no significant differences between the two subject groups in relation to the external images of scientists. The subjects turned out to have low fixed external images. The scientifically gifted students had a better understanding of the internal images of scientists than ordinary elementary school students. Both the subject groups fumed out to be influenced by the press media and off-campus education, thinking that scientists served as inventors producing something useful in daily lift rather than as researchers studying natural phenomena or laws. It was found out that both groups admired Edison. The ordinary students respected Einstein and Jang Yeong-Sil whereas the scientifically gifted students respected Curie, Jug Yeong-Sil, and Nobel. The subjects admired them because of their achievements instead of their backgrounds or individual characteristics.

• Journal of the Korean Institute of Gas
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• v.19 no.5
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• pp.7-12
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• 2015

Hydrogen is usually produced by using syngas generated by the fuel reforming for natural gas so far. The further process is needed for increasing the hydrogen yield of syngas. However, the process for upgrading the hydrogen yield is accompanied by additional energy sources and economic costs. Thus related studies on the method for using as a mixture in itself have been conducted in order to utilize more efficiently syngas. The effect on the engine performance for methane/syngas mixture of 30kW spark ignition gas engine for power generation has been investigated in this study. As a result, it was found that the combustion phenomena such as the maximum in-cylinder pressure and crank angle at that time have been improved by methane/syngas mixture. Through these, fuel conversion efficiency could be enhanced by about 98% of methane/hydrogen mixture and $NO_x$ emissions could be reduced by about 12% of methane-hydrogen mixture.

• Journal of the Korean Society of Hazard Mitigation
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• v.8 no.1
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• pp.97-102
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• 2008

The Natural Resource Conservation Service Curve Number(NRCS-CN) method is one of the widely used methods for computation of runoff from a basin. However, NRCS-CN method has a weak point in that the spatial land use distribution characteristics are ignored by using area-weighted CN value. This study developed a runoff estimation algorithm which can reflect the spatial land-use distribution. The algorithm consists of Moglen's theory and a developed flow accumulation estimation program in FORTRAN. Comparisons between the results from area-weighted CN method and this study showed reasonably good agreement with measured data of experimental watersheds. The developed program predicted lower runoff than the conventional NRCS-CN method. As a conclusion, this study proposes a new design direction which can simulate real runoff phenomena. And the developed program could be applied into runoff minimization design for a basin development.

• Economic and Environmental Geology
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• v.46 no.1
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• pp.71-84
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• 2013

Most gas hydrates (GH) occur in ocean sediments. Global GH reserves are estimated to be $10^{13}{\sim}20{\times}10^{15}m^3$, which is nearly 1,000 times the amount of current world energy consumption. Methane hydrate (MH) has the potential to be developed into future natural gas resources to replace traditional oil and gas resources, and thus MH production technologies such as depressurization, inhibitor injection, thermal stimulation, and $CO_2-CH_4$ substitution need to be further developed. MH production, which is expected to be in test production until 2014 in Korea, is focused on the development of GH production technologies for use in the commercial production of methane gas. This study compares MH production technology and its ability to meet the twin goals of being both effective and environmentally friendly while taking into consideration the complex phenomena of GH decomposition.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2010.05a
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• pp.223-225
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• 2010

In order to minimize the casualties and damages from natural disasters, local terrain and weather phenomena need to be constantly monitored. Various weather monitoring systems are designed to collect and monitor the weather information for disaster prevention. Nowadays, wireless sensor networks have been widely used to transmit the weather information and collected by the base station at a regular interval. In this paper, disaster prevention monitoring system for efficient data transfer of weather information such as temperature, humidity and illumination are designed. Weather information is able to burst the data transmission based on storage of flash memory. Telosb sensor node are used in the research; programmed by nesC language used by TinyOS.

• Journal of the Korean Geosynthetics Society
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• v.13 no.4
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• pp.45-56
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• 2014

Frozen ground in cold region consists of an upper active layer and lower permafrost which is permanently frozen land. During the summer season, the air temperature is high enough to make the frozen ground melt, which causes the reduction of soil strength and thaw settlement. These phenomena result in structural instability, so it is necessary to apply frozen ground stability techniques. Thermosyphon is a closed natural two-phase convection device to maintain the ground temperature below $0^{\circ}C$ by extracting heat from the ground and discharges it into the atmosphere. Experimental and numerical investigation has been performed to estimate the effect of the refrigerant filling ratio in thermosyphon using R-134a refrigerant and the thermal conductance of the thermosyphon.

• Hwankyungkyoyuk
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• v.21 no.2
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• pp.51-67
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• 2008

The purpose of this study is to develop and applicate the elementary environmental textbook in order to solve its problem and to improve attitude related to the Asian dust. The results in this research are as follows. First, it was showed that three groups who composed of teachers, parents and students in the elementary school had recognized the serosities and problems caused by the Asian dust form TV, and that such problems was associated with increase of the desertification and the global warming. Especially the student group insist that the cause in Asian dust is due to the natural phenomena or industrialization. Second, as a result in analysis on the Asian dust through both textbooks on the 7th elementary curriculum and subsidiary textbooks, contents concerning Asian dusts was little or noting. In addition, in the subjects of Science, Society and Health for the 5th and 6th grade students in the elementary school, they were explained partially as one of the air pollutants. Third, the elementary environmental textbook on the Asian dust was developed for the 5th and 6th grade students. The textbook is composed of four contents on the material which is harmful of the human health and life in Asian dust, the special news of Asian dust, and the best answer to solve Asian dust as well as the cause and the source of Asian dust. Forth, as a result in classes using the environmental textbook developed by four themes about the Asian dust, its application is meaningful in the level of p value in the view of knowledge, awareness and attitude of the experiment group. They was more improved in 37%, 14%, and 15%, respectively, than the comparative group. In conclusion, the environmental textbook related to Asian dust will play an important role in useful tool to understand the right knowledge, awareness, and attitude which makes an effort on its effective management in the elementary school.