• 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.

• 한국멀티미디어학회논문지
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• 제20권12호
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• pp.1940-1950
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• 2017

The security threat types in underwater communication networks environment are almost the same as the terrestrial, but the security of mechanisms the terrestrial RF-based networks environment can not be directly applied due to not only the limited resources of each node but also unsafe channel such as low propagation delay, high bit error rate etc. Nevertheless there has not been much research on the security of underwater acoustic communication networks. Therefore, in this paper analyzes the differences between the terrestrial communication networks and underwater acoustic communication networks, and identifies issues that are the starting points of underwater communication networks security research.

• 한국환경과학회지
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• 제9권3호
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• pp.201-208
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• 2000

PCBs and DDE were determined in the soil samples and the Korean striped field mice, Apodemus agrarius, collected at six localities in Changwon and one locality in Gaduck Island from August 1997 to May 1998. The residual level of PCBs in soils, in which the concentrations of high chlorinated compounds were much higher than those of low chlorinated ones, was highest in the industrial area(IA) in Changwon(60.7 ng/g in average), whereas those of DDE in soils was highest in Gaduck Island(331.9 ng/g in average). However, the levels of each compound detected from soils in the respective remaining places were relatively low. The similar tendency as in the soils was observed in the mice, indicating that the concentration of pollutants in the mice could denote the status of pollution in the terrestrial environment. The composition of PCB congeners in the mice, however, was different from that of soils, but similar to those of other mammals. Moreover, the residual levels of PCBs and DDE in pregnant females from which fetuses were removed were lower than those of males and non-pregnant females. It suggests that these compounds accumulated in pregnant females might have been transferred to the fetuses through placenta as in other mammals. Judging from the above facts, it is suggested that the striped field mouse can be an useful biological index to evaluate the contamination in mammals inhabiting terrestrial environment.

• 지질공학
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• 제29권3호
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• pp.251-264
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• 2019

본 연구에서는 설악산국립공원 천불동 계곡에 위치한 암반사면의 낙석 위험블록을 대상으로 지상 LiDAR를 이용하여 변위 모니터링을 수행하였다. 모니터링 지점은 기존에 낙석이 발생되었거나 낙석발생이 예상되는 귀면암 인근 및 오련폭포 인근 암반사면을 선정하였다. 대상 지점의 암반사면 위험블록에 대한 모니터링은 지상 LiDAR를 이용하여 약 7개월 동안 5차례 촬영을 진행하였다. 지상 LiDAR 촬영 결과 토대로 변위량을 분석한 결과 폐색영역의 보간을 통해 발생한 오차와 식생 활력도의 차이에 의한 오차가 분석결과에 크게 영향을 미치는 것으로 확인되었다. 이와 같은 외부영향을 최소화하기 위해서는 실제 촬영지점을 대상으로 변위량을 탐지하여야 한다. 대상구간 암반사면 위험블록에서 지상 LiDAR 촬영 및 변위량을 분석한 결과 변위량이 매우 작게 발생하였으며, 대부분 오차범위 아래의 변위량을 보이므로 실제 변위가 발생하였다고 판단하기 어렵다. 한편, 지상 LiDAR를 이용하여 암반사면 위험블록 모니터링을 수행하기 위해서는 식생이 없는 구간을 선정하는 것이 중요하며, 식생이 존재하는 구간의 PountCloud 제거 및 Mesh Model 분석은 데이터 신뢰성 확보에 가장 중요한 항목임을 알 수 있다.

• 천문학회보
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• 제36권2호
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• pp.93.1-93.1
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• 2011

Radio wave from a compact radio source such as a quasar are scattered by irregularities of electron density. The scattered waves interfere with each other as they propagate to the Earth producing diffraction patterns on the ground. This phenomenon is called interplanetary scintillation (IPS). The IPS pattern contains the information of solar wind velocities and density fluctuations passing across a line-of-sight (LOS) from an observer to a radio source. The IPS is a useful tool which allows us to measure the solar wind in three dimensional space inaccessible to in situ observations. Although the IPS measurement is an integral of solar wind velocities and density fluctuations along the LOS, which causes degradation of accuracy, we have succeeded to develop computer assisted tomography (CAT) analysis to remove the effect of LOS integration. These techniques greatly improved the accuracy of determinations of solar wind velocity structures. In this talk we present our IPS observation system and long-term variation of global solar wind structures from 1980-2009, then we focus on recent peculiar solar wind properties.

• 한국컴퓨터정보학회논문지
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• 제13권3호
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• pp.115-122
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• 2008

지상파 DMB 수신기 및 그 응용제품은 일반적인 수신 시험, 잡음에 대한 수신상태 실험, 방송의 출력신호 변화에 따른 수신상태 변화 측정 및 수신환경의 변화에 따른 수신상태 등의 다양한 시험을 필요로 한다. 따라서 지상파 DMB 관련 연구기관과 제조업체 및 기타 유관 기관에서는 실시간으로 지상파 DMB 방송을 시뮬레이션 할 수 있는 시스템이 필요하다. 본 논문은 이러한 시험에 필요한 지상파 DMB 방송의 신호 스트림을 실시간으로 생성시키고, 실제의 방송과 유사하게 시뮬레이션하는 시스템의 개발에 관한 연구이다. 본 시스템은 PCI 인터페이스의 T-DMB 신호 생성기와 다양한 기능의 프로그램 모듈로 구성된 시뮬레이션 소프트웨어로 구성된다. 본 연구를 통하여, 경제적인 개발비용으로 PC 를 이용한 소프트웨어 기반의 T-DMB 시뮬레이션 시스템 구현이 가능함을 보였다. 또한 다양한 실험을 통하여 본 시뮬레이션 시스템의 성능을 평가하고 추후 연구 방향을 제시하고자 한다.

• 전기전자학회논문지
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• 제16권1호
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• pp.7-14
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• 2012

본 논문에서는 지상파 디지털 TV방송의 수신 여부를 판단할 수 있는 시청자 기반의 방송 수신율 산정방안을 연구하여 객관적이고 신뢰성 있는 방송 수신율을 산정하는 방안을 제안하였다. 기존의 방송 수신율 평가는 인구분포와는 무관하게 행정구역별로 제한된 지점에서의 전계강도 측정과 화질평가를 통하여 방송 수신율을 산정하므로 큰 오차가 발생하며, 실시간으로 수신환경을 평가할 수 없다는 문제점을 지닌다. 본 연구에서는 시청자들의 주거환경을 고려하기 위해 통계청의 가구통계와 환경부의 토지피복도를 결합한 모폴로지를 추출하고, 이를 주파수자원 분석시스템에 연계하여 실시간으로 수신율을 산정하는 방안을 제안하였다. 제안방법은 대상지역을 거주지역과 비주거지역으로 세분화한 후 수신율 산정 과정에서 고려함으로써 기존방법 보다 객관적이고 신뢰성 높은 방송 수신율을 실시간적으로 산정할 수 있다.

• 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.

• 한국환경독성학회:학술대회논문집
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• 한국환경독성학회 2001년도 춘계심포지움 및 학술발표회
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• pp.107-113
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• 2001

Consumer Product compounds are used in homes and disposed in wastewater where they typically receive waste treatment. After treatment, sludge and effluent are released to the environment resulting in the potential exposure of terrestrial and aquatic organisms to these compounds. To ensure the environmental safety of these compounds, the environmental risk posed by chemicals released into the environment must be assessed. A reasonable, consistent and cost-effective method to conduct environmental risk assessments and to prioritize testing of these chemicals is needed which addresses risk to organisms residing in the terrestrial and aquatic compartments of the environment. This paper provides a fundamental understanding of the technical basis of environmental risk assessment using the major surfactant(i.e., LAS) used in the laundry detergent industry worldwide as a case study.

• 천문학회보
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• 제32권1호
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• pp.34.2-34.2
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• 2007