• 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.

• 한국건설관리학회논문집
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• 제5권5호
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• pp.76-83
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• 2004

건축공사가 대형화됨에 따라 대규모의 지하공간을 구축하기 위한 흙막이 공사의 중요성도 점차 커지고 있다. 따라서 적정한 흙막이공법의 선정은 건축공사의 원활한 수행을 위해서 매우 중요한 요소 중의 하나라 할 수 있다. 그러나 흙막이공법의 설계와 시공이 분리되어 있는 우리나라의 경우에는 많은 설계변경이 발생하고 있고, 이러한 설계변경은 건설사업의 성패를 좌우하는 공사비와 공기 측면에서 지대한 영향을 줄 수 있다. 본 연구에서는 이러한 흙막이공법에 대한 의사결정 단계에서 활용할 수 있는 사례기반추론기법을 활용한 흙막이 공법 선정 모델을 구축하여 제안하고, 이를 실제 시공된 사례를 이용하여 모델을 평가하였다. 사례연구 결과 유사사례와 추천사례에서 비교적 정확한 결과를 도출하는 것으로 나타났다. 흙막이공법의 선정과 같이 의사결정과정에서 고려해야할 요소가 많고, 이러한 영향요소를 정량화하기 어려운 분야에서는 본 연구에서 활용된 사례기반추론기법이 매우 유용하게 활용될 수 있을 것으로 사료된다.

• 전기의세계
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• 제22권6호
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• pp.33-51
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• 1973

To lower the earth resistance shall be one of the most effective method for the prevention of lightening damage on power transmission line. In this report, in order to investigate various characteristic necessary to lowering the earth resistance, the following experiments have been made at 154KV U1San-PoHang T/L, 154KV YoSu-SoonChun T/L and so on. 1. Measurement of Earth specific resistance, 2. Efficiency of Earthing of concrete foundation for steel structure., 3. Efficiency of Earthing with counter poise., 4. Compound impulse test with foundation of steel structure and counter poise. With the above investigate a guidance have been prepared for the effective work-performance of steel structure.

• Geomechanics and Engineering
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• 제16권3호
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• pp.321-329
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• 2018

Classic braced walls use struts and wales to minimize ground movements induced by deep excavation. However, the installation of struts and wales is a time-consuming process and confines the work space. To secure a work space around the retaining structure, an anchoring system works in conjunction with a braced wall. However, anchoring cannot perform well when the shear strength of soil is low. In such a case, innovative retaining systems are required in excavation. This study proposes an innovative earth-retaining wall that uses in situ soil confined in dual sheet piles as a structural component. A numerical study was conducted to evaluate the stability of the proposed structure in cohesionless dry soil and establish a design chart. The displacement and factor of safety of the structural member were monitored and evaluated. According to the results, an increase in the clearance distance increases the depth of safe excavation. For a conservative design to secure the stability of the earth-retaining structure in cohesionless dry soil, the clearance distance should exceed 2 m, and the embedded depth should exceed 40% of the wall height. The results suggest that the proposed method can be used for 14 m of excavation without any internal support structure. The design chart can be used for the preliminary design of an earth-retaining structure using in situ soil with dual steel sheet piles in cohesionless dry soil.

• Geomechanics and Engineering
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• 제17권6호
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• pp.515-525
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• 2019

The calculation of active earth pressure behind retaining wall is a typical three-dimensional (3D) problem with spatial effects. With the help of limit analysis, this paper firstly deduces the internal energy dissipation power equations and various external forces power equations of the 3D retaining wall under the nonlinear strength condition, such as to establish the work-energy balance equation. The pseudo-static method is used to consider the effect of earthquake on active earth pressure in horizontal state. The failure mode is a 3D curvilinear cone failure mechanism. For the different width of the retaining wall, the plane strain block is inserted in the symmetric plane. By optimizing all parameters, the maximum value of active earth pressure is calculated. In order to verify the validity of the new expressions obtained by the paper, the solutions are compared with previously published solutions. Agreement shows that the new expressions are effective. The results of different parameters are given in the forms of figures to analysis the influence caused by nonlinear strength parameters.

• 대한지구과학교육학회지
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• 제3권3호
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• pp.198-208
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• 2010

This work describes a preliminary investigation to a learning model based on cybernetics and radical constructivism. To achieve this purpose, main ideas of cybernetics, i.e., negative feedback, difference, self-regulation, equilibrium, and purpose-directed behavior was analysed under radical constructivism. Powers' model, which consists of hierarchically arranged negative feedback systems, is introduced into this work. This was based on the claim that living organisms behave to control perceptions. By adding the notion of scheme from the view of radical constructivism, a learning procedure, which consists of six steps, was suggested in this work.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 1990년도 PROCEEDINGS OF THE FIRST KOREA-JAPAN JOINT GEOTECHNICAL SEMINAR ON EXCAVATION and TUNNELING IN URBAN AREAS
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• pp.129-144
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• 1990

This paper is an introduction of measured samples of a peripheral ground displacement resulting from excavation work, and the work carried out to minimize the displacement of the earth retaining wall and the adjacent structures.

• 한국농촌건축학회논문집
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• 제18권2호
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• pp.1-9
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• 2016

Vernacular perspectives had been ignored in the movement of modern architecture. This study's purpose was to review vernacular perspectives and to identify vernacular characteristics of earth architecture. Six representative contemporary earth architects were selected, and then their works were analyzed. Themes of vernacular architecture based of Frampton's critical regionalism were emerged. Findings were as following: 1) constructed by considering the local climate and the region's natural characteristics, 2) constructed with local materials seeking integration of structure and finishing work, 3) having tectonic form included regional characteristics, 4) creating space of various senses and expression of texture through earth modeling, 5) presenting homogeneity of sense of place between site and architecture, and 6) pursuing ecological and sustainable architecture. These characteristics of contemporary earth architecture reflect the vernacular architecture inherited continually in architectural history. Therefore, contemporary earth architecture has been in line with contemporary architecture aiming for sustainability.

• 한국건설관리학회:학술대회논문집
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• 한국건설관리학회 2007년도 정기학술발표대회 논문집
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• pp.977-982
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• 2007

건설자동화 장비의 개발에 있어서 주변 사물을 인식하고 효과적으로 모델링하기 위한 노력은 지속적으로 이루어져 왔다. 이 연구는 지능형 굴삭 로봇 개발의 요소기술로서, 3D 레이저 스캐너를 이용하여 토공 작업환경을 3차원으로 모델링하고, 객체화된 모델링 정보를 이용하여 지능적인 작업 계획을 수립하기 위한 기반 연구이다. 이 연구에서는 먼저 3D 레이저 스캐너의 시장 동향을 분석하였고 토공 작업환경을 대상으로 3D 레이저 스캐너의 성능을 비교 분석하여 토공 현장에서 적합한 3D 레이저 스캐너를 선정하였다. 그리고 3D 모델링 시스템의 하드웨어 구서을 제시하였고 전체 소프트웨어의 컨셉을 설계하였다. 다음으로 소프트웨어 상세 기능 설계 및 사용자 인터페이스 설계를 통해 향후 photogrammetry 및 객체인식 기술의 적용을 위한 프레임워크를 구축하였다. 이 연구에서는 실제 토공현장을 대상으로 개발된 소프트웨어와 토탈 스테이션을 이용하여 타겟간의 상대거리를 측정하고 3D 모델링 시스템의 정확성을 측정하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 제37회 하계학술대회 논문집 전기설비
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• pp.89-90
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• 2006

Recent earth systems not only make earth resistance decreased by installing earth electrode but also are demanded by earth construction for the protection of human life and equipments through total investigation about circumstances. Layer constructions in Jeju island consist of multi-layer of scoria, rocks and shale except clay layers on the surface, which needs the construction of the coring earth electrode suitable in the condition of the area. For this reason, we've used the coring earth electrode. But the coring earth electrode is expected to slow down the performance of this equipment according to the progress of time changing the effects. It is also applied for the stability of earth system construction and management after the construction work analyzing the condition of the earth system. Therefore, this is actually focused on the analysis on measuring the earth resistance and the soil resistivity that cover the range where the remarkable contrast can be expected to be seen in the layer structures.