• 지질공학
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• 제26권4호
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• pp.571-581
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• 2016

To understand the mechanical properties of fault rocks, data from 584 in situ and laboratory tests on fault rocks from 33 tunnels were analyzed. The unit weights of the fault rocks range from 17.3 to $28.2kN/m^3$ and the cohesion and friction angles vary from 5 to 260 kPa and $14.7^{\circ}$ to $44.0^{\circ}$, respectively. The modulus of deformation and elasticity were generally < 200 MPa. In most cases, the uniaxial compressive strength was < 0.5 MPa, and Poisson's ratios were mainly 0.20-0.35. The mechanical properties of individual rock types were analyzed using box plots, revealing that the cohesion values and friction angles of shale and phyllite have relatively wide inter-quartile ranges and that the modulus of deformation and elasticity of shale have the lowest values of all rock types. In the analysis of mechanical properties by components of fault rocks, the largest values were shown in damage zones of individual rock types.

• 자원환경지질
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• 제29권5호
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• pp.615-622
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• 1996

Slope stability analysis was conducted using remote sensing and Geoscientific Information System (GIS) as a part of natural hazard assessment around Chungju area. Landsat TM band 5 and 7 which contain more information about geological structure and geography are chosen and processed to analyse regional geological structure. Through image processing technique such as PCA, HFF, edge detection and enhancement, regional lineament can be mapped and identified. The lineament density map is constructed based on summed length of lineaments per unit area and the study area can be divided into 7 structural domains. Various factors of slope stability analysis such as geology, slope aspect, degree of slope, landcover, water shed as well as characterized structural domain are constructed as a database of GIS. Rating and weighting of each factor for slope stability analysis is decided by considering environmental geological characteristics of study area. Spatial analysis of regional slope stability is examined through overlaying technique of the GIS. The result of areal distribution of slope stability shows that the most unstable area is all over Jaeogae-ni, Hyangsan-ni and Mt. Daedun.

• Journal of Astronomy and Space Sciences
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• 제38권2호
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• pp.145-155
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• 2021

In this work, preliminary launch opportunities from NARO Space Center to the Sun-Earth Lagrange point are analyzed. Among five different Sun-Earth Lagrange points, L1 and L2 points are selected as suitable candidates for, respectively, solar and astrophysics missions. With high fidelity dynamics models, the L1 and L2 point targeting problem is formulated regarding the location of NARO Space Center and relevant Target Interface Point (TIP) for each different launch date is derived including launch injection energy per unit mass (C3), Right ascension of the injection orbit Apoapsis Vector (RAV) and Declination of the injection orbit Apoapsis Vector (DAV). Potential launch periods to achieve L1 and L2 transfer trajectory are also investigated regarding coasting characteristics from NARO Space Center. The magnitude of the Lagrange Orbit Insertion (LOI) burn, as well as the Orbit Maintenance (OM) maneuver to maintain more than one year of mission orbit around the Lagrange points, is also derived as an example. Even the current work has been made under many assumptions as there are no specific mission goals currently defined yet, so results from the current work could be a good starting point to extend diversities of future Korean deep-space missions.

• Spatial Information Research
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• 제18권5호
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• pp.143-161
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• 2010

본 연구에서는 3차원 지형공간정보를 기반으로 한 정밀한 토공량 모델링을 통해 토목 건설공사의 효율성을 향상시키기 위한 토공량 계산 프로그램인 EWS 프로그램을 개발하였다. EWS 프로그램은 LiDAR DEM을 이용한 정확한 토공량 계산과 건설장비의 단위 작업량을 기반으로 한 토공 공정계획수립이 가능하도록 개발되었다. 또한 계산된 결과를 건설현장에서 보다 직관적인 이해하고 이에 따른 분석 결과를 쉽게 공유할 수 있도록 하기 위해 Google Earth를 이용한 3D 가시화도 지원이 가능하다. 개발된 프로그램의 현장 적용성 검증을 위해 DAS 프로그램과의 토공량 계산 결과 및 토공 이동계획을 비교하였으며, 검증을 위한 대상지역으로 경기도 포천시 신북면 일원의 신포천 변전소 건설현장을 선정하였다. 최종적인 비교 결과, 본 연구에서 개발된 EWS 프로그램을 이용하는 경우 정밀한 3차원 지형공간정보를 통해 정확한 토공량 계산이 가능하며, 보다 합리적인 토량 이동계획 및 토공작업의 수립할 수 있어 건설현장에서의 생산성 향상 효과를 기대할 수 있을 것으로 판단되었다.

• 자원환경지질
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• 제40권3호
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• pp.319-330
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• 2007

청송 무포산응회암은 경상분지 북동부 화산암류에서 하나의 냉각단위로 구별되는 층서단위이다. 이 응회암은 그 입도에 의하면 대부분 응회암에 속하고 구성원에 의하면 파리질 응회암에 속한다. 대부분 부석과 샤드가 일정하게 배열되고 심하게 편평화되어 용결엽리를 발달시키며 여러 가지 흐름지시자를 보여준다. 무포산응회암에서 부석 정향배열에 의한 유상선구조로부터 이동 패턴, 암편과 부석의 와상배열, 용결엽리의 비대칭 유상습곡 등의 흐름 지시자, 암편과 부석의 최대입경의 측방점이, 그리고 구성원 함량의 측방점이에 의하면 이 응회암을 집적시킨 화쇄류는 남동부에서 공급되었던 것으로 해석된다.

• 한국지구과학회지
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• 제21권3호
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• pp.219-229
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• 2000

구성주의 학습은 의미구성의 적극적인 과정이며, 학생 스스로 개인의 흥미와 관심, 능력에 따라 스스로 학습목표를 결정할 수도 있다. 본 연구에서는 구성주의에 입각한 학습 교재와 교수-학습 모델을 개발하고 이를 서울의 한 초등학교 학생들에게 적용하였다. 4학년 2학기 ‘지층과 화석’ 단원을 학생과 교사의 토론을 중심으로 재구성하였으며, 안내-실천-표현-합의-발전의 단계에 따라 1개월 동안 수업을 실시하고 그 결과를 정리해 보았다.

• 대한지구과학교육학회지
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• 제3권3호
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• pp.163-174
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• 2010

The purpose of this study is to device the teaching-learning method and the evaluating method on 'free inquiry' which is newly introduced in 2007 revised curriculum. The teaching-learning models which apply 'free inquiry' are 'group investigation', 'PBL', 'project investigation' and 'IIM'. And the unit which apply 'free inquiry' on the fourth grade and the second semester in the elementary science. The results of this study are as follows: First, The person leading the lesson is not a teacher but learners. The focus of teaching-learning is not a unit but topic, problem or project on the science textbook. A teacher's role is not the deliverer of knowledge but the guide of learning. Second, the outcome of applying group investigation, PBL project investigation and IIM to 'free inquiry' is improvements of the problem-solving ability and the self-directed learning ability as well as building scientific attitude and social skills as educational effect in commonly. Third, to apply 'free inquiry' efficiently, teachers should understand each subject very well, teach a class with a thorough and concrete plan, and try to evaluate objectively.

• 한국농촌건축학회논문집
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• 제2권2호
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• pp.115-126
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• 2000

Retaining walls are used to prevent excessive movement of retained soils. Typical retaining walls include gravity, reinforced concrete, reinforced earth and tie-back. However, from a practical viewpoint there are still drawbacks among these often constructed retaining walls. New types of retaining walls constructed with precast concrete blocks are proposed. This type of retaining wall is incorporates each blocks interconnected with adjacent block by connecting unit to build up a flexible retaining-wall system. This paper focus to behavior characteristics includes deformation and distribution of lateral earth pressure by loading tests and FEM analysis. For model tests, a 1/10 scale reduce models are manufactured include unevenness part, drainage hole and connecting unit and steel wire used to connect each blocks with adjacent block. To simulate the real retaining walls closely, uneven parts are interconnected each other and the construction type of blocks and wall front inclination are varied to investigate the relative displacement of individual block and the location of maximum deformation of wall as increasing surcharging. Additionally, PENTAGON3D, which solve the geotechnical and other problem, used for verifying and comparing with model tests.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2004년도 제22회 춘계학술대회논문집
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• pp.306-313
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• 2004

The microwave discharge ion engine generates plasmas of both the main ion source and the neutralizer using 4㎓ microwave without discharge electrodes and hollow cathodes, so that long life and durability against oxygen and air are expected. The MUSES-C “HAYABUSA” asteroid explorer installing four microwave discharge ion engines “$\mu$10s” was launched into deep space by M-V rocket No.5 on May 9, 2003. After vacuum exposure and several runs of baking for reduction of residual gas the ion engine system established the continuous acceleration of the spacecraft toward the asteroid “ITOKAWA”. The Doppler shift measurement of the communication microwave revealed the performance of ion engines, which is 8mN thrust force for a single unit with 3,200sec specific impulse at 23mN/㎾ thrust power ratio. At the end of 2003 the accumulated operational time exceeded 8,000 hour and unit. HAYABUSA will execute the Earth swing-by on June 2004 and arrive at the asteroid in 2005 and return to Earth in 2007.

• 한국지구과학회지
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• 제45권4호
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• pp.338-348
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• 2024

In the mid-eastern part of the Yellow Sea, large-scale shelf ridges originated from erosion on sand-mud successions that have been presently eroded by strong tidal currents. A three-layered in situ geoacoustic model is provided down to 50 m for the subbottom sedimentary succession of a 45 m water depth using the Hamilton method. The succession is divisible into two-type units of Type-A and Type-B using high-resolution seismic profiles with a deep-drilled YSDP-104 core of 44.0 m in depth below the seafloor. Type-A unit mainly comprises sandy or gravelly sediments, whereas Type-B unit mostly consists of tidal muddy sediments with some thinner sand beds. P-wave speed values are positively compatible with the mean grain size and sediment type of the core sediments. For actual modeling, the geoacoustic property values of the models were compensated to in situ depth values below the seafloor. The detailed geoacoustic model contributes to simulating sound transmission through the sedimentary successions in erosional shelf ridges of variable geoacoustic properties distributed in shallow-water environments of the mid-eastern Yellow Sea.