• Journal of Radiation Protection and Research
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• 제45권1호
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• pp.16-25
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• 2020

Background: To investigate radiological effects on biota, it is necessary to assess radiation dose for flora and fauna living in a terrestrial ecosystem. This paper presents a dynamic model to assess radioactivity concentration and radiation dose of terrestrial flora and fauna after a nuclear accident. Materials and Methods: Litter, organic soil, mineral soil, trees, wild crops, herbivores, omnivores, and carnivores are considered the major components of a terrestrial ecosystem. The model considers the physicochemical and biological processes of interception, weathering, decomposition of litter, percolation, root uptake, leaching, radioactive decay, and biological loss of animals. The predictive capability of the model was investigated by comparison of its predictions with field data for biota measured in the Fukushima forest area after the Fukushima nuclear accident. Results and Discussion: The predicted radioactive cesium inventories for trees agreed well with those for evergreens and deciduous trees sampled in the Fukushima area. The predicted temporal radioactivity concentrations for animals were within the range of the measured radioactivity concentrations of deer, wild boars, and black bears. The radiation dose for the animals were, for the whole simulation time, estimated to be much smaller than the lower limit (0.1 mGy·d^-1) of the derived consideration reference level given by the International Commission on Radiological Protection for terrestrial flora and fauna. This suggested that the radiation effect of the accident on the biota in the Fukushima forest would be insignificant. Conclusion: The present dynamic model can be used effectively to investigate the radiological risk to terrestrial ecosystems following a nuclear accident.

• 교육녹색환경연구
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• 제6권2호
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• pp.25-52
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• 2007

This paper is focused on the economical efficiency of the geothermal heat pump system in school. As the importance of problems of environment and energy becomes larger, the development and distribution of energy-saving technology in the whole nation has become influential. This paper is intended, targeting on school buildings scattered all over the country, to evaluate the introduction and possibility of a terrestrial heat system which is in the first stage of introduction in the country, through energy consumption and efficiency in case where a terrestrial heat system is introduced. To do that, the author performed a qualitative analysis of the heat pump system using various terrestrial heat energy and the system introduced to existing school buildings and, through the analysis, made tentative evaluation on the most environment-friendly and energy saving type system. Also, the author performed simulation analysis using a currently typical school building standard and, on the basis of this result, conducted efficiency analysis of various heat pump systems. The conclusion according to synthetical analysis & evaluation can be summarized as follows. In case a heat pump system is introduced to a school building, it was deemed the investment in the early stage would increase, but the investment could be collected within 5~6 years through reduction of large operation expenses. Also, it was analyzed in case of terrestrial heat contracted heat mode using midnight electric power among heat pump systems, not only early investment but also operation expenses could be reduced to a great extent. Accordingly in case the system using terrestrial heat energy is applied to the school buildings that are to be newly built or repaired in the future, it will provide an object-lesson to students as well as contributing to energy saving.

• Journal of Radiation Protection and Research
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• 제16권2호
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• pp.67-74
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• 1991

육상 섭취 경로에 따른 내부 피폭선량 계산 모델 KFOOD의 파라메터 불착실성 및 민감도를 몬테칼로법을 사용하여 수치 분석하였다. 쌀을 통한 섭취 경로의 경우 KFOOD 코드에 의한 예측치는 아주 보수적인 값을 나타내었다 모델에서 민감도가 큰 입력변수는 방사능의 침적속도와 식물전이제수였다.

• ETRI Journal
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• 제36권4호
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• pp.519-527
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• 2014

An integrated multi-beam satellite and multi-cell terrestrial system is an attractive means for highly efficient communication due to the fact that the two components (satellite and terrestrial) make the most of each other's resources. In this paper, a terrestrial component reuses a satellite's resources under the control of the satellite's network management system. This allows the resource allocation for the satellite and terrestrial components to be coordinated to optimize spectral efficiency and increase overall system capacity. In such a system, the satellite resources reused in the terrestrial component may bring about severe interference, which is one of the main factors affecting system capacity. Under this consideration, the objective of this paper is to achieve an optimized resource allocation in both components in such a way as to minimize any resulting inter-component interference. The objective of the proposed scheme is to mitigate this inter-component interference by optimizing the total transmission power - the result of which can lead to an increase in capacity. The simulation results in this paper illustrate that the proposed scheme affords a more energy-efficient system to be implemented, compared to a conventional power management scheme, by allocating the bandwidth uniformly regardless of the amount of interference or traffic demand.

• 한국항행학회논문지
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• 제21권4호
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• pp.402-412
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• 2017

방송 기술과 통신 기술의 융합은 유비쿼터스 네트워크를 위한 핵심 기술 중 하나이다. 본 논문에서는 AT-DMB(advanced terrestrial digital multimedia broadcasting) 방송망과 통신망의 융합망을 제안하고, MIIS(media independent information server/service)를 통한 방송 시스템과 통신 시스템 간 연동을 제공하는 융합 시스템을 제안한다. 특히, 방송통신 융합망에서 QoS(Quality of Service)와 전력절감의 향상을 위한 fast wakeup and connection 기술을 제안한다. 제안하는 기술은 사용자 단말의 휴지기 인터페이스로 유입되는 서비스 지연과 해당 인터페이스의 전력소모를 최소화하는 기술이다. 끝으로, 시뮬레이션 및 성능분석을 통해 제안하는 기술이 서비스 지연을 감소시키면서 전력소모를 최소화할 수 있음을 확인하였다.

• ETRI Journal
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• 제42권1호
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• pp.36-45
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• 2020

A priority-based data communication approach, developed by employing cognitive radio capacity for sensor nodes in a wireless terrestrial sensor network (TSN), has been proposed. Data sensed by a sensor node-an unlicensed user-were prioritized, taking sensed data importance into account. For data of equal priority, a first come first serve algorithm was used. Non-preemptive priority scheduling was adopted, in order not to interrupt any ongoing transmissions. Licensed users used a nonpersistent, slotted, carrier sense multiple access (CSMA) technique, while unlicensed sensor nodes used a nonpersistent CSMA technique for lossless data transmission, in an energy-restricted, TSN environment. Depending on the analytical model, the proposed wireless TSN environment was simulated using Riverbed software, and to analyze sensor network performance, delay, energy, and throughput parameters were examined. Evaluating the proposed approach showed that the average delay for sensed, high priority data was significantly reduced, indicating that maximum throughput had been achieved using wireless sensor nodes with cognitive radio capacity.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2009년도 학술발표회 초록집
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• pp.529-534
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• 2009

Climate models, both global and regional, have increased in sophistication and are being run at increasingly higher resolutions. The Land Surface Models (LSMs) coupled to these climate models have evolved from simple bucket models to sophisticated Soil-Vegetation-Atmosphere Transfer (SVAT) schemes needed to support complex linkages and processes. However, some underpinnings of terrestrial hydrologic parameterizations so crucial in the predictions of surface water and energy fluxes cause model errors that often manifest as non-linear drifts in the dynamic response of land surface processes. This requires the improved parameterizations of key processes for the terrestrial hydrologic scheme to improve the model predictability in surface water and energy fluxes. The Common Land Model (CLM), one of state-of-the-art LSMs, is the land component of the Community Climate System Model (CCSM). However, CLM also has energy and water biases resulting from deficiencies in some parameterizations related to hydrological processes. This research presents the implementation of a selected set of parameterizations and their effects on the runoff prediction. The modifications consist of new parameterizations for soil hydraulic conductivity, water table depth, frozen soil, soil water availability, and topographically controlled baseflow. The results from a set of offline simulations are compared with observed data to assess the performance of the new model. It is expected that the advanced terrestrial hydrologic scheme coupled to the current CLM can improve model predictability for better prediction of runoff that has a large impact on the surface water and energy balance crucial to climate variability and change studies.

• 한국방사성폐기물학회:학술대회논문집
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• 한국방사성폐기물학회 2019년도 춘계학술논문요약집
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• pp.373-374
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• 2019

• 한국환경과학회지
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• 제27권12호
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• pp.1169-1178
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• 2018

Two man-made carbon emissions, fossil fuel emissions and land use emissions, have been perturbing naturally occurring global carbon cycle. These emitted carbons will eventually be deposited into the atmosphere, the terrestrial biosphere, the soil, and the ocean. In this study, Simple Global Carbon Model (SGCM) was used to simulate global carbon cycle and to estimate global carbon budget. For the model input, fossil fuel emissions and land use emissions were taken from the literature. Unlike fossil fuel use, land use emissions were highly uncertain. Therefore land use emission inputs were adjusted within an uncertainty range suggested in the literature. Simulated atmospheric $CO_2$ concentrations were well fitted to observations with a standard error of 0.06 ppm. Moreover, simulated carbon budgets in the ocean and terrestrial biosphere were shown to be reasonable compared to the literature values, which have considerable uncertainties. Simulation results show that with increasing fossil fuel emissions, the ratios of carbon partitioning to the atmosphere and the terrestrial biosphere have increased from 42% and 24% in the year 1958 to 50% and 30% in the year 2016 respectively, while that to the ocean has decreased from 34% in the year 1958 to 20% in the year 2016. This finding indicates that if the current emission trend continues, the atmospheric carbon partitioning ratio might be continuously increasing and thereby the atmospheric $CO_2$ concentrations might be increasing much faster. Among the total emissions of 399 gigatons of carbon (GtC) from fossil fuel use and land use during the simulation period (between 1960 and 2016), 189 GtC were reallocated to the atmosphere (47%), 107 GtC to the terrestrial biosphere (27%), and 103GtC to the ocean (26%). The net terrestrial biospheric carbon accumulation (terrestrial biospheric allocations minus land use emissions) showed positive 46 GtC. In other words, the terrestrial biosphere has been accumulating carbon, although land use emission has been depleting carbon in the terrestrial biosphere.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2009년도 9th International Meeting on Information Display
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• pp.1125-1128
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• 2009

Conversion of light energy to electrical energy by using a solar cell has long been considered as one of the option for an electrical energy supply in the future. In the past, commercial use was restricted largely to remote area applications where conventional electricity is expensive. Recently, the major application of the solar cells changed to become generation of residential electricity in urban areas where the electricity is already supplied by the conventional grid. This paper covers the current market and technology status of the solar cells and future prospect of their terrestrial applications. Reviewing market trend, this paper discusses high efficiency approach in silicon solar cells, low cost approach in silicon solar cells and finally covers future prospects of silicon solar cells.