• Nuclear Engineering and Technology
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• v.45 no.1
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• pp.1-12
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• 2013

This paper describes the radiation doses to human and non-human biota in the Republic of Korea, as a result of the Fukushima nuclear accident. By using the measured airborne activity and ground deposition, the effective and thyroid doses of five human age groups (infant, 5 years, 10 years, 15 years and adult) were estimated by the ECOSYS code, and the whole body absorbed dose rate of the eight Korean reference animals and plants (RAPs) was estimated by the K-BIOTA (the Korean computer code to assess the risk of radioactivity to wildlife). The first-year effective and thyroid human doses ranged from 5.7E-5 mSv in the infant group to 2.0E-4 mSv in the 5 years group, and from 5.0E-4 mSv in the infant group to 3.4E-3 mSv in the 5 years group, respectively. The life-time (70 years) effective and thyroid human doses ranged from 1.5E-4 mSv in the infant group to 3.0E-4 mSv in the 5 years group, and from 6.0E-4 mSv in the infant group to 3.5E-3 mSv in the 5 years group, respectively. The estimated maximum whole body absorbed dose rate to the Korean RAPs was 6.7E-7 mGy/d for a snake living in soil (terrestrial biota), and 2.0E-5 mGy/d for freshwater fish (aquatic biota), both of which were far less than the generic dose criteria to protect biota from ionizing radiation. Also, the screening level assessment for ERICA's (Environmental Risks from Ionizing Contaminants: Assessments and management) limiting organisms showed that the risk quotient (RQ) for the estimated maximum soil and water activity was significantly less than unity for both the terrestrial and freshwater organisms. Conclusively, the radiological risk of the radioactivity released into the environment by the Fukushima nuclear accident to the public and the non-human biota in the republic of Korea is considered negligible.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1402-1403
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• 2011

Photovoltaic solar energy policy in the keynote of the world in the development of new technologies in terms of renewable energy sources has been a great interest. Solar energy is the energy density, low light intensity, temperature, and a lot of areas affected by the difference, the effective use difficult. For the installation of photovoltaic solar power systems to develop farmland or forest land resulting from deforestation has become such a problem. In this paper, a way to resolve these issues as part of the development of the reservoir water through the efficient use of land and water resources through the eco-friendly energy production, water quality improvement, the cooling effect of solar modules, solar water system has the advantage of was installed. Terrestrial solar systems installed under the same conditions and solar radiation, power, module temperature, ambient temperature and analyzed. Through this award to demonstrate the effectiveness of the solar system is.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.55 no.1
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• pp.35-40
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• 2006

Heat-pump system has a special feature that provides heating operation in winter season and cooling operation in summer season with a single system. It also has a merit that absorbs and makes use of wastewater heat, terrestrial heat, and heat energy from the air. Because heat-pump system uses midnight electric power, it decreases power peak load and is very economical as a result. By using the property that energy source is converted to low temperature when losing the heat, high temperature energy source is used to provide heating water and low temperature energy source is used to provide cooling water simultaneously in summer season. This study made up a heat-pump system with 4 air heat sources and a water heat source and implemented the optimal operation algorithm that works with numbers of heat pumps to operate them efficiently. With the heat-pump system, we applied it to cooling and heating operation in summer season operation mode in a real building.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 1994.11a
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• pp.14-16
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• 1994

The development of proton exchange membrane fuel cells(PEMFCs) with high energy efficiencies and high power densities is gaining momentum because their performance characteristics are attractive for terrestrial(power sources for electrical vehicles, stand-by power), space and underwater application[1]. Fuel cells are capable of running on non-petroleum fuels such as methanol, natural gas or hydrogen and also have major impact on improving air quality. They virtually eliminate particulates, NO$_{x}$, SO$_{x}$, and significant reduce hydrocarbons and carbon monoxide. Especially, fuel cell-battery hybrid power sources appear to be well suited to overcome both the so-called battery problem(low energy density) and the fuel cell problem(low power density)[2].[2].

• Transactions of the Korean hydrogen and new energy society
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• v.25 no.5
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• pp.541-549
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• 2014

The monthly-average meteorological data, in particular, the monthly average daily terrestrial horizontal insolation are required for designing solar thermal energy systems. In this paper, the dynamic thermal performance of a flat plate solar collector system is numerically investigated through a year from the monthly average insolation data in Seoul. For a specified data set of solar collector system, the dynamic behaviors of total solar radiation on the tilted collector surfaces, heat loss from the collector system, useful energy and collector efficiency are analyzed from January to December by a mathematical simulation model. In addition, the monthly average daily total solar radiation, useful energy, and daily collector efficiencies through a year are estimated. The simulated results show that the average total radiation is highest in March and the useful energy is highest in October, while the total radiation and the collector efficiency are lowest in July.

• Korean Journal of Environmental Biology
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• v.37 no.3
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• pp.317-334
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• 2019

The present study was conducted to investigate the differences in managed farming practices, including low-intensive farming, duck farming, and golden apple snail farming, in a rice ecosystem by comparing terrestrial arthropod communities. A total of 75 species from 70 genera belonging to 43 families in 11 orders were identified from 9,622 collected arthropods. Araneae, Hemiptera, and Coleoptera were the richest taxa. Collembola was the most abundant, followed by Diptera, Hemiptera, and Araneae. Bray-Curtis similarity among the farming practices was very high (76.7%). The biodiversity of each farming practice showed a similar seasonality pattern. The richest species group was the predators, followed by the herbivores. The species richness and diversity of ecologically functional groups among the farming practices were not statistically significant, except for the abundance of predators in golden apple snail farming. The biodiversity seasonality of ecological functional groups in each farming practice showed similar patterns. The biomass of Araneae, Hemiptera, Coleoptera, and Diptera was greater than the other taxa, in general. The biomass of each ecological functional group showed little difference and the biomass fluctuation patterns in each farming practice were almost the same. Collectively, the community structures and biodiversity of terrestrial arthropods among the farming practices in the present study were not different. The present study may contribute to sustain rich biodiversity in irrigated rice fields and to advanced studies of food webs or energy flow structures in rice fields for ecological and sustainable agriculture.

• Journal of IKEEE
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• v.22 no.4
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• pp.1068-1072
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• 2018

In underwater communications, there are many challenges due to energy limitations, long propagation delay, low data rate, and high power loss, unlike terrestrial RF communications. Especially, the propagation delay of underwater acoustic channel is five orders of magnitude higher than in electro-magnetic terrestrial channels due to the low speed of sound(1,500m/s). Thus, the MAC protocols for terrestrial communications are not suitable for underwater network. In this paper, we studied the considerations for MAC protocol in underwater acoustic channel. Here, we concentrated on CSMA based MAC protocols. From the results, we confirmed that the number of control packets has an important effect on the performance in underwater environment. These results would be useful in designing MAC protocols for underwater acoustic communications.

• Journal of the Korean earth science society
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• v.43 no.2
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• pp.312-323
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• 2022

This study began with the hypothesis of whether "solar radiation" and "terrestrial radiation" can be replaced by "visible radiation" and "infrared radiation", respectively. To this end, we investigated the perceptions of high school students who completed the Earth Science I course through a questionnaire to reveal how they perceived each concept. We also analyzed the descriptions and illustrations of textbooks that may have affected their perceptions. All of the students who participated in the questionnaire recognized solar radiation as radiation emitted only in the visible light region. About 35% of the students recognized convection, conduction, and latent heat as energy transfer by radiation in the Earth's heat budget. By analyzing six types of Earth Science I textbooks in the 2015 revised curriculum, we observed that two types introduced the terms "shortwave radiation" and "longwave radiation" but had no explanation for them, while the other two described solar radiation as "radiation mainly in the visible light region" or "radiation in short wavelengths". Regarding solar and terrestrial radiation in the last two types, there was no explanation for the wavelength regions, or ambiguous terms such as "short wavelength" and "long wavelength" were used. In addition, the two textbooks contained some errors in the illustration of the energy budget. Considering that textbooks described solar and terrestrial radiation without defining the exact terms for shortwave and longwave radiation, learners are likely to recognize solar and terrestrial radiation as visible and infrared radiation, respectively. This finding implies that vague statements or errors in textbooks can cause or reproduce students' misconceptions. The discussion in this study is expected to be used as a helpful reference material for teaching and learning processes regarding the Earth's radiation equilibrium and heat budget, and thereby contribute to proposing reasonable description plans for future textbook writing.

• Korean Journal of Soil Science and Fertilizer
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• v.45 no.2
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• pp.156-161
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• 2012

Marine biomass is considered an important substrate for anaerobic digestion to recovery energy i.e. methane. Nevertheless, marine biomass has attracted little attention by researchers compared to terrestrial feedstock for anaerobic digestion. In this study, biochemical methane potential (BMP) test was used to evaluate generation of renewable energy from starfish. A cumulative biogas yield of $748{\pm}67mL\;g^{-1}VS^{-1}$ was obtained after 60 days of digestion. The cumulative methane yield of $486{\pm}28mL\;CH_4\;g^{-1}VS^{-1}$ was obtained after 60 days of digestion. The methane content of the biogas was approximately 70%. The calculated data applying the modified Gompertz equation for the cumulative $CH_4$ production showed good correlation with the experimental result obtained from this batch study. Since the result obtained from this study is comparable to results with other substrates, marine biomass can be co-digested with food waste or swine wastewater to produce $CH_4$ gas that will help to reduce the gap in global energy demand.

• Journal of Radiation Protection and Research
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• v.30 no.3
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• pp.149-159
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• 2005

The purpose of this paper is to present the general attributes of the current IAEA programs and their prospects in the arena of protection of the marine and terrestrial environment, thus responding to a need to attain a consolidated understanding of the Agency's programs for an effective and efficient deployment of the respective national R&D projects in Korea. In addition, the considerable and beneficial benefits from a participation in the IAEA programs have been analyzed and their immediate relevance has been emphasized. A strategy for the enhancement of an active participation in the program and its efficient implementation has also been established. It is expected that the suggested recommendations such as the long term strategy and the relevant guidelines will be helpful in establishing a nuclear policy for the further development of the international cooperative projects in the future.