• 천문학회지
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• 제34권4호
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• pp.317-319
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• 2001

The response of the earth's magnetosphere to the variation of the solar wind parameters and Interplanetary magnetic field (IMF) has been stud}ed by using a high-resolution, three-dimension magnetohydrodynamic (MHD) simulation when the WIND data of velocity Vx, plasma density, dynamic pressure, By and Bz every 1 minute were used as input. Large electrojet and magnetic storm which occurred on October 21 and 22 are reproduced in the simulation (fig. 1). We have studied the energy transfer and tail reconnect ion in association with geomagnetic storms.

• ETRI Journal
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• 제46권2호
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• pp.333-346
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• 2024

Various techniques for noninvasively focus microwave energy on lesions have been proposed for thermotherapy. To focus the microwave energy on the lesion, a focusing parameter, which is referred to as the magnitude and phase of microwaves radiated from an external array antenna, is very important. Although the finite-difference time-domain (FDTD)-based time-reversal (TR) focusing algorithm is widely used, it has a long processing time if the focusing target position changes or if optimization is needed. We propose a technique to obtain multistatic data (MSD) based on Green's function and use it to derive the focusing parameters. Computer simulations were used to evaluate the electric fields inside the object using the FDTD method and Green's function as well as to compare the focusing parameters using FDTD- and MSD-based TR focusing algorithms. Regardless of the use of Green's function, the processing time of MSD-based TR focusing algorithms reduces to approximately 1/2 or 1/590 compared with the FDTD-based algorithm. In addition, we optimize the focusing parameters to eliminate hotspots, which are unnecessary focusing positions, by adding phase-reversed electric fields and confirm hotspot suppression through simulations.

• Proceedings of the National Institute of Ecology of the Republic of Korea
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• 제1권1호
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• pp.58-67
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• 2020

Terrestrial ecosystems influence climate change via their climate regulation function, which is manifested within the carbon, water, and energy circulation between the atmosphere and surface. However, it has been challenging to quantify the climate regulation of terrestrial ecosystems and identify its regional distribution, which provides useful information for establishing regional climate-mitigation plans as well as facilitates better understanding of the interactions between the climate and land processes. In this study, a land surface model (LSM) that represents the land-atmosphere interactions and plant phenological variations was introduced to assess the contributions of terrestrial ecosystems to atmospheric warming or cooling effects over East Asia over the last half century. Three main climate-regulating components were simulated: net radiation flux, carbon exchange, and moisture flux at the surface. Then, the contribution of each component to the atmospheric warming or cooling (negative or positive feedback to the atmosphere, respectively) was investigated. The results showed that the terrestrial ecosystem over the Siberian region has shown a relatively large increase in positive feedback due to the enhancement of biogeochemical processes, indicating an offset effect to delay global warming. Meanwhile, the Gobi Desert shows different regional variations: increase in positive feedback in its southern part but increase in negative one in its eastern part, which implies the eastward movements of desert areas. As such, even though the LSM has limitations, this model approach to quantify the climate regulation is useful to extract the relevant characteristics in its spatio-temporal variations.

• 대한지리학회지
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• 제48권3호
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• pp.321-335
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• 2013

경상북도 울진군 진복리 해안 사빈에서 2009년 6월부터 9월까지 이벤트성의 강한 저기압이 발생한 전 후 시기와 그 외 다양한 파랑에너지 환경에서 형성된 미지형변화를 8차례 지상라이다로 측정하여 고해상도 자료로 획득하였다. 지상라이다 분석뿐 아니라 입도분석 결과에서도 파고가 높은 파랑에 의해 발생한 진복리 사빈의 남북 간 변화가 뚜렷하였다. 태풍으로 인해 강한 파랑이 접근한 시기에는 사빈의 면적과 부피가 감소하였고, 파고가 낮은 기간에는 사빈의 부피가 증가하였다. 9월의 파고가 높은 파랑이 발생한 이후 북쪽 사빈은 침식되어 해안선이 후퇴하였고, 남쪽은 퇴적작용을 받아 해안선이 전진하였다. 남북 사빈의 침식, 퇴적현상을 비교한 결과, 진복리 사빈은 모래가 어느 정도 해저로 유출되었을지라도 사빈 내부에서 재이동하였다.

• 대순사상논총
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• 제34집
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• pp.263-292
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• 2020

大巡真理会广泛地吸收了诸多古老的传统文化, 形成独具特色的宗教文化, 而对风水文化的借鉴和改造就是其中的一个重要方面。在 《典经》 的记载中, 就有许多关于风水文化的内容。《典经》 中的风水文化, 既从传统的风水学说中汲取养分, 也进行了许多的创造性地理解。借助大巡真理会的教义对风水文化进行理解, 这就使得 《典经》 呈现出别具一格的特色。通过对 《典经》 中有关风水文化的整理, 本文试图从地气, 山势以及明堂这三个方面来讨论大巡真理会的风水文化。透过风水文化的视角对 《典经》 展开深入探究, 有助于更好地理解 《典经》 这一宗教圣典的深刻内容和神圣意义。

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제16권8호
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• pp.2736-2750
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• 2022

As demands for the maritime communications increase, a variety of functions and information are required to exchange via elements of maritime systems, which leads communication traffic increases in maritime frequency bands, especially in VHF (Very High Frequency) band. Thus, effective resource management is crucial to the future maritime communication systems not only to the typical terrestrial communication systems. VHF data exchange system (VDES) enables to utilize more flexible configuration according to the communication condition. This paper focuses on the VDES communication system among VDES terminals such as shore stations, ship stations and aids to navigation (AtoN) to address efficient resource allocation. We propose a resource management method considering a MIMO (Multiple Input Multiple Output) technique in VDES, which has been widely used for modern terrestrial wireless networks but not for marine environments by scheduling the essential communication resources. We introduce the general channel model in marine environment and give two metrics, spectral and the energy efficiencies to examine our resource scheduling algorithm. Based on the simulation results and analysis, the proposed method provides a possibility to enhance spectral and energy efficiencies. Additionally, we present a trade-off relationship between spectral and energy efficiencies. Furthermore, we examine the resource efficiencies related to the imperfect channel estimation.

• 자원환경지질
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• 제31권1호
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• pp.69-84
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• 1998

A geochemical study was carried out to define how marine shore sediments are related to their terrestrial source rocks in the region of Taean and Byunsan Peninsula, western Korea. The lithology of the coastal part of the study area is composed of Pre-Cambrian granite gneiss, schist, Jurassic terrestrial sedimentary rocks, and Cretaceous plutonic intrusives. Shore sediments are transported from three drainage tributaries. The sediments consist of quatrz with clay minerals, such as illite, kaolinite, smectite, chlorite. Heavy minerals include hematite, ilmenite, rare amount of zircon and apatite. Compared to those in coastal rocks, amount of heavy minerals in the sediments is considerably low. The low content of heavy minerals is thought to be attributed to the heavy mineral detainment in the river beds and influences of tidal currents which cause heavy minerals to accumulate in specific spots. Chemical composition of the major and trace elements, trace elements, and REE chondrite normalized pattern suggest that shore sediments transported from the corresponding drainage tributary show close mineralogical and geochemical relationships with the source rocks distributed in the Taean and Byunsan Peninsula.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2006년도 추계학술대회
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• pp.20-23
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• 2006

Geothermal energy is the natural heat of the Earth. Enormous amounts of thermal energy are continuously generated by the decay of radioactive isotopes of underground rocks and stored in the Earth's interior. Therefore, geothermal energy is one of the most important sustainable energy resources. Recent trends of geothermal energy exploitation technologies focus on the Earth scientific approach to geothermal heat pump system, enhanced geothermal system, aquifer thermal energy storage, underground thermal energy storage, and fluid/heat flow model ing for geothermal wells. Geothermal heat pump distribution in Korea is still in its starting phase in terms of areal utilization sense, we, however, expect to come up with national supply of over 1,000,000 toe by 2020

• Journal of Radiation Protection and Research
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• 제15권2호
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• pp.87-100
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• 1990

자연환경 방사선의 주 요소의 하나인 지각 방사선에 의한 피폭선량을 정량적으로 측정 해석하기 위하여 24개월간에 걸친 TLD에 의한 연속 적산선량 측정과 주기적인 감마선 분광분석을 수행하였다. TLD로는 LiF PTFE disk형을 사용하였으며 감마선 분광분석에서는 $3&{\phi}{\times}3'$원주형 Nal(Tl) 섬광검출기와 휴대형 다중파고 분석기 (4096 ch)를 사용하였다. 측정한 선량은 모두 실효 선량당량으로 평가하였으며 부수적으로 우주선 전리 성분에 의한 선량당량도 평가할 수 있었다. 분산 가중 평균값을 취한 결과에 의하면 대전 지역의 측정점에서 지각 방사선과 우주선 전리 성부의 체외 피폭에 의한 년간 실효 선량당량은 각각 $564{\pm}4\;{\mu}Sv(64.8{\pm}0.5nSv{\cdot}h^{-1}$ 및 $300{\pm}2\;{\mu}Sv(34.3{\pm}0.2nSv{\cdot}h^{-1}$로 나타났다.

• Journal of Astronomy and Space Sciences
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• 제15권1호
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• pp.163-174
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• 1998

To study the origin of organic matter in meteorite, terrestrial rocks which contain or-ganic compounds similar to the ones found in carbonaceous chondrites are studied and compared with Muchison meteorite. Hydrocarbon molecules were extracted by benzene and methanol from bituminous coal and oil shale and the extracts were partitioned into aliphatic, aromatic, and polar fractions by silica gel column chromatography. Carbon isotopic ratios in each fractions were analysed by GC-C-IRMS. Molec-ular compound identifications were carried by GC-MS Engine. Bituminous coal and oil shale show the organic compound composition similar to that of meteorite. Oil shale has a wide range of ${\delta}^{13}C,-20.1%_0~-54.4%_0$ compared to bituminous coal, $-25.2%_0~34.3%_0$. Delta values of several molecular compounds in two terrestrial samples are different. They show several distinct distributions in isotopic ratios compared to those of meteorite; Murchison meteorite has a range of ${\delta}^13C\;from\;-13%_0\;to\;+30%_0$. These results provide interpretation for the source and the formation condition of each rock, in particular alteration and migration processes of organic matter. Especially, they show an important clue whether some hydrocarbon molecules observed in meteorite are indigenous or not.