• 대한임베디드공학회논문지
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• 제9권4호
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• pp.219-227
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• 2014

Natural disasters such as a ground collapse and a landslide have broken out due to the climate change of the Korea and the reckless expansion of cities and roads. The climate changes and the reckless urbanization have made the ground weak. Thus, it is important to keep a close eye on the highly weakened landslide and to prevent its natural disasters. In order to prevent these disasters, this paper presents a system of recognizing the road slide condition by measuring the displacements using laser scanner instrument. The previous system of monitoring the road slide has some problems as inaccurate recognition due to using only images from a camera, or expensive system such as artificial satellites and aircraft systems. To solve this problem, our proposed system uses the 3D range data from the laser scanner for measuring the accurate displacement of the road slide and optical flows from the Lucas-Kanade algorithm for recognizing the road slide in the image.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제45회 하계 정기학술대회 초록집
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• pp.127.1-127.1
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• 2013

Recent experimental evidence that fluorinated graphene creates local magnetic moments around F adatoms has not been supported by semilocal density-functional theory (DFT) calculations where the adsorption of an F adatom induces no magnetic moment in graphene. Here, we show that such an incorrect prediction of the nonmagnetic ground state is due to the self-interaction error inherent in semilocal exchange-correlation functionals. The present hybrid DFT calculation for an F adatom on graphene predicts not only a spin-polarized ground state with a spin moment of ${\sim}1{\mu}_B$, but also a long-range spin polarization caused by the bipartite nature of the graphene lattice as well as the induced spin polarization of the graphene states. The results provide support for the experimental observations of local magnetic moments in fluorinated graphene.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 추계학술대회논문집
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• pp.103-108
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• 2004

In this study, examined heavy-weight floor impact sound to structure that have slab thickness of 4 form at a standard laboratory through noise and vibration measured. The results show that the nature Natural frequency increased according to change of thickness of each slab by finite element analysis, and acceleration value decreased. Results of measurements of noise and vibration at a standard laboratory, the slab 210, 240mm structures was construed result such as finite element analysis but the slab 150, 180mm structures is construed that influence in vibration acceleration level because edge condition has condition that contact to ground. Therefore, in modelling process for analysis, is thought that need that condition analyzes examining element influencing about structure that contact to ground.

• 한국산업융합학회 논문집
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• 제20권2호
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• pp.125-132
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• 2017

The slope of the road in the forest area has a characteristic of steep slope, so natural disasters such as slope collapse occur. The slope displacement observation technique according to landslide is being studied as a method to observe a wide area and a method to observe a small area. This is a study on high-precision digital map generation using ground LiDAR. It is possible to create a high - precision digital map by minimizing the US side using the 3D LiDAR in the steep slope area where the GPS and Total Station measurement are difficult in the maintenance of the danger slope area. It is difficult to objectively evaluate whether the contour lines generated by LiDAR are correct and it is considered necessary to construct a test bed for this purpose. Based on this study, if terrain changes such as landslides occur in the future, it will be useful for measuring slope displacement.

• 한국응용곤충학회지
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• 제34권3호
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• pp.256-265
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• 1995

사과원 잡초군락이 해충 및 천적발생에 미치는 영향을 알아보기 위하여 제초제를 살포하여 잡초를 제거한 구(제초구)와 수관하부까지 잡초를 키우면서 인력으로예초한 구(예초구)에서 수상의 해충 및 천적과 잡초상의 곤충류를 조사하여 다음과 같은 결과를 얻었다. 응애류와 진딧물의 발생은 처리간에 유의성있는 차이는 없었으나, 응애류의 경우는 예초구에서 발생이 적은 경향이었다. 사과굴나방의 경우 예초구에서 1993년에는 피해엽률이 10% 정도 낮았고, 1994년은 4% 정도 낮은 발생을 보였다. 응애류와 진딧물의 천적류 발생은 쳬초구에서 높은 경향이었으나 큰 차이는 없었으며 사과굴나방의 기생청 천적류는 예초구에서 1993년에는 6~10%, 1994년에는 20~25% 높은 발생을 보였다. 사과원 잡초상에서 포충망을 이용 곤충류를 채집 조사한 결과, 사과해충은 발견되지 않았으며, 사과해충 천적류로서 좀벌류, 고치벌류, 애꽃노리재, 무당벌류, 풀잠자리류 등이 발견되었다. 사과생육기간중 잡초상 및 수상에서 군충군집변화는 상이하였다. 수상에서의 곤충군집형성에 약제살포가 큰 영향을 주었으나, 잡초상에서는 약제살포에 상대적으로 안정된 군집이 유지되었다. 결론적으로 사과원 잡초는 수상의 사과해충 및 천적발생에 영향을 주고 있었으며, 사과굴나방 기생벌같은 기주특이적인 천적들은 수상이동에 의하여 밀도억제작용을 하였고, 잡초상에 먹이가 풍부하거나 또는 광식성인 천적들은 잡초상 곤충군집에 연관되어 수상의 해충밀도에 큰 영향을 주지 못했다.

• 한국지반신소재학회논문집
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• 제13권1호
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• pp.23-31
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• 2014

본 연구에서는 레이저 거리측정기를 이용하여 사면의 지표변위를 효과적으로 측정하는 방법을 제안하였다. 기존 사면의 지표변위 혹은 지중변위를 측정하기 위한 복잡하고 고가의 장비 대신에 제안된 방법을 적용할 경우 보다 간편하고 쉽게 지표변위를 측정할 수 있다. 레이저 거리측정기는 적색 레이저를 측정을 원하는 피사체에 시준하면 반사되는 레이저를 이용해 거리를 측정하는 기기로 작동방법이 용이하고 측정정밀도도 아주 높으며, 가격이 저렴한 장점이 있다. 제안된 방법의 활용가능성을 검토하기 위하여 실제 지표변위가 지속적으로 발생되는 현장에 적용하였다. 대상지역은 석탄폐석 적치장의 영향으로 하부에 위치하는 절취사면 및 자연사면의 여러 위치에서 지표변위가 발생된 현장이다. 대상지역에 지표변위를 직접적으로 측정하기 위하여 6개의 측정구간과 26개의 측정지점을 선정하였다. 일정한 기간 동안 제안된 방법을 이용하여 측정한 결과 누적 지표변위량 뿐만 아니라 지표변위속도까지 측정이 가능하였다. 그리고 이들 결과를 종합적으로 분석하여 지표변위 발생방향을 확인 및 예측할 수 있다.

• Geomechanics and Engineering
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• 제32권3호
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• pp.307-319
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• 2023

Ground fissures have a huge effect on the integrity of surface structures. In high-intensity ground fissure regions, however, land resource would be wasted and city building and economic development would be limited if the area avoiding principle was used. In view of this challenge, to reveal the seismic response and seismic failure characteristics of ground fissure sites, a shaking table test on model soil based on a 1:15 scale experiment was carried out. In the test, the spatial distribution characteristics of acceleration response and Arias intensity were obtained for a site exposed to earthquakes with different characteristics. Furthermore, the failure characteristics and damage evolution of the model soil were analyzed. The test results indicated that, with the increase in the earthquake acceleration magnitude, the crack width of the ground fissure enlarged from 0 to 5 mm. The soil of the hanging wall was characterized by earlier cracking and a higher abundance of secondary fissures at 45°. Under strong earthquakes, the model soil, especially the soil near the ground fissure, was severely damaged and exhibited reduced stiffness. As a result, its natural frequency also decreased from 11.41 Hz to 8.05 Hz, whereas the damping ratio increased from 4.8% to 9.1%. Due to the existence of ground fissure, the acceleration was amplified to nearly 0.476 m/s², as high as 2.38 times of the input acceleration magnitude. The maximum of acceleration and Arias intensity appeared at the fissure zone, which decreased from the main fissure toward both sides, showing hanging wall effects. The seismic intensity, duration and frequency spectrum all had certain effects on the seismic response of the ground fissure site, but their influence degrees were different. The seismic response of the site induced by the seismic wave that had richer low-frequency components and longer duration was larger. The discrepancies of seismic response between the hanging wall and the footwall declined obviously when the magnitude of the earthquake acceleration increased. The research results will be propitious to enhancing the utilizing ratio of the limited landing resource, alleviation of property damages and casualties, and provide a good engineering application foreground.

• Structural Engineering and Mechanics
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• 제33권6호
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• pp.725-745
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• 2009

In this paper, probabilistic seismic performance assessment of a typical non-seismic RC frame building representative of a large inventory of existing buildings in developing countries is conducted. Nonlinear time-history analyses of the sample building are performed with 20 large-magnitude medium distance ground motions scaled to different levels of intensity represented by peak ground acceleration and 5% damped elastic spectral acceleration at the first mode period of the building. The hysteretic model used in the analyses accommodates stiffness degradation, ductility-based strength decay, hysteretic energy-based strength decay and pinching due to gap opening and closing. The maximum inter story drift ratios obtained from the time-history analyses are plotted against the ground motion intensities. A method is defined for obtaining the yielding and collapse capacity of the analyzed structure using these curves. The fragility curves for yielding and collapse damage levels are developed by statistically interpreting the results of the time-history analyses. Hazard-survival curves are generated by changing the horizontal axis of the fragility curves from ground motion intensities to their annual probability of exceedance using the log-log linear ground motion hazard model. The results express at a glance the probabilities of yielding and collapse against various levels of ground motion intensities.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2000년도 봄 학술발표회논문집
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• pp.111-118
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• 2000

Concrete cracking due to the temperature gradient across the wall, caused by the difference in temperature between cryogenic liquid natural gas stored and surrounding environment of in-ground LNG storage tank, is investigated in this study. Crack propagation of concrete LNG tank is effectively simulated by using a layered degenerated shell element. In addition, material nonlinearity is taken into consideration on the basis of the nonlinear elastic-orthotropic model. Finally, numerical analysis for a real LNG storage tank is conducted with the objective to verify the efficiency of the introduced model.

• 한국토양동물학회지
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• 제9권1_2호
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• pp.32-43
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• 2004

Herein, 15 species of the ground beetles are reported from Jejudo. Of these, 4 species, Bradycellus subditus (Lewis,1879), Colpodes rubriolus Bates, 1883, Pentagonica angulosa Bates, 1873, and Porotachys recurvicollis(Andrewes, 1925) are listed for the first time from the Korean Peninsula. The Korean tachyine species are briefly discussed.