• 지구물리
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• 제3권1호
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• pp.37-48
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• 2000

다성분 복소 트레이스 분석법을 이용하여 지진에 의한 지면운동을 밝히고자 컴퓨터 합성 탄성파 자료와 자연 지진 자료를 대상으로 파선방향의 입자운동을 분석하였다. 합성 탄성파 자료에 적용시킨 결과, 실체파 합성 부분에서는 도달시각, 지속시간, 접근각 등을 정확히 찾을 수 있으며, 레일리파도 쉽게 인지된다. 규모 7.3의 심발 지진 자료로부터 입자운동의 분극특성을 계산한 결과, 종파의 수직성분과 수평성분의 순간위상차, 순간역타원율, 접근각은 각각 약 ${\pm}180^{\circ},\;0{\sim}0.25,\;-30^{\circ}{\sim}-45^{\circ}$의 값을 가지며, 이러한 분극특성으로부터 진원시간함수는 $6{\sim}7\;s$ 정도 지속되는 것으로 분석된다. 횡파의 경우는 순간위상차가 일정하지 않으며, $0{\sim}0.3$의 순간역타원율과 거의 수직의 접근각을 나타낸다. 횡파 도달 직전에 기록된 비교적 저주파의 신호는 분극특성으로부터 횡파와는 구별되는 종파의 일종으로 해석된다. 종파와 횡파의 도달시각을 이용하여 구한 속도와 파선변수는 각각 8.633 km/s, 4.762 km/s와 0.074 s/km, 0.197 s/km이며 동포와송비는 0.281로 계산된다.

• 화약ㆍ발파
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• 제30권1호
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• pp.29-36
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• 2012

기폭위치가 지반진동에 미치는 영향에 대한 연구들을 살펴보면 발파진동의 복합적인 원인에 반하여 단편적인 연구로 진행되거나 적용범위가 연구가 이루어진 해당 현장만으로 국한적으로 나타나며 발파설계 인자로서 이용되는 데 한계를 보였다. 이에 본 연구는 기폭위치에 따라 발파진동의 전파 특성을 파악하기 위해서 공간격, 저항선, 천공장 그리고 장약량 등을 달리하여 총 72회의 단일공 시험발파를 실시하여 발파진동 예측식을 도출하였다. 도출된 발파진동 예측식으로부터 기폭위치에 따른 최대입자속도의 노모그램 분석을 통해 진동특성을 규명하였다. 또한, 국토해양부의 "도로공사 노천발파 설계 시공 지침"에 제시된 표준발파공법의 공법별 경계 기준 장약량인 0.5, 1.6, 5, 15kg을 적용하여 기폭위치별 진동 감쇄경향을 비교 분석하여 발파설계의 인자로 사용할 수 있도록 제안하였다.

• Journal of Ecology and Environment
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• 제33권4호
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• pp.351-361
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• 2010

The primary purposes for using fire are to enhance marsh vegetation to support waterfowl, and to manage invasive plant species. The study was conducted for two consecutive years in 2004 and 2005, investigating the effects of prescribed fire regimes on vegetation biomass in tidal brackish marsh areas of the Blackwater National Wildlife Refuge located on the eastern shore of Maryland, USA, that are under relatively similar environmental conditions. Four different burn regimes (i.e., annual burn, 3-5 year burn, 7-10 year burn, and no burn) were applied in the study. Above- and below-ground vegetation biomass samples as affected by the different burn regimes were harvested in each year for five plant species native to the marsh; Distichlis spicata, Spartina alterniflora, Schoenoplectus americanus, Spartina cynosuroides and Spartina patens. No significant difference was found either in total above-ground biomass or in above-ground biomass by species between burn regimes in 2004. However, more total above-ground biomass was produced in annual burn regime in 2005 than in the other burn regimes. There were no consistent effects of burning on vegetative biomass production by species, but it seemed D. spicata was somewhat benefited by prescribed burning for its biomass production. Moreover, the stem density for D. spicata under annual burn regime was significantly higher than that in the other burn regimes, showing some positive effects of burning on vegetation. The below-ground biomass was significantly greater in 2004 than in 2005, yet with no significant difference between burn regimes in either year. A longer-term monitoring is strongly recommended.

• Geomechanics and Engineering
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• 제21권2호
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• pp.111-122
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• 2020

In most cases in urban areas, construction of divergence tunnel should take into account proximity to existing tunnel in operation. This inevitably leads to deformation of adjacent structures and surrounding ground. Preceding researches mainly dealt with reinforcing of the diverging section for the stability including the pillar. This has limitations in investigating the interactive effects between existing structures and surrounding ground due to the excavation of the divergence tunnel. In this study, the complex interactive behavior of pile, the operating tunnel, and the surrounding ground according to horizontal offsets between the two adjacent tunnels was quantitatively analyzed based on conditions diverged from operating tunnel in urban areas. The effects on ground structures confirmed by analyzing the ground surface settlements, pile settlements, and the axial forces of the pile. The axial forces of lining in operating tunnel investigated to estimate their impact on existing tunnel. In addition, in order to identify the deformation of the surrounding ground, the close range photogrammetry applied to the laboratory model test for confirming the underground displacements. Two-dimensional finite element numerical analysis was also performed and compared with the results. It identified that the impact of excavating a divergence tunnel decreased as the horizontal offset increased. In particular, when the horizontal offset was larger than 1.0D (D is the diameter of operating tunnel), the impact on existing structures further reduced and the deformation of surrounding ground was concentrated at the top of the divergence tunnel.

• 한국지반공학회논문집
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• 제37권7호
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• pp.25-34
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• 2021

연약지반으로 이루어진 준설매립부지는 지반이 매우 연약한 상태이기 때문에 설계시 정확한 지지력을 계산하는 것은 어렵고 복잡한 요인들이 고려되어야 한다. 최근까지 준설매립지를 대상으로 다양한 연약지반처리공법을 설계하고 있지만, 초기 장비진입을 위해서 기존 Meyerhof(1974) 복합토층 지지력 계산으로 안전율을 예측하고 있다. 기존 방정식들은 시공성 안전을 확보한다는 차원에서 연약지반 지지력을 과소평가하여 경제적 비용이 증가될 수 있다. 따라서 본 연구에서는 현장여건이 고려된 지지력 식을 제안하였다. 이를 위하여 이론적인 방정식에서 고려되지 못하는 토목섬유의 봉합사 역할과 봉합인장강도가 지지력에 끼치는 영향을 실험으로 제시하여 적절한 연약지반 지지력을 평가할 수 있도록 제시하였다. 그리고, 현장시험으로 수정방정식 지지력의 안정성이 평판재하시험으로 실측한 값과 비교하여 적절성을 확인하였다. 향후 준설토 매립지반의 설계와 시공시 본 연구 결과가 기초자료로 활용될 것으로 판단된다.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2005년도 춘계학술대회
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• pp.403-407
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• 2005

Objective of the research is to demonstrate solar thermal space and ground heating system which is integrated to a greenhouse culture facility for reducing heating cost, increasing the value of product by environment control, and developing advanced culture technology by deploying solar thermal system. Field test for the demonstration was carried out in horticulture complex in Jeju Island. Medium scale solar hot water system was installed in a ground heating culture facility. Reliability and economic aspect of the system which was operated complementary with thermal storage and solar hot water generation were analyzed by investigating collector efficiency, operation performance, and control features. Short term day test on element performance and Long term test of the whole system were carried out. Optimum operating condition and its characteristics were closely investigated by changing the control condition based on the temperature difference which is the most important operating parameter. For establishing more reliable and optimal design data regarding system scale and operation condition, continuous operation and monitoring on the system need to be further carried out. However, it is expected that, in high-insolation areas where large-scale ground storage is adaptable, solar system demonstrated in the research could be economically competitive and promisingly disseminate over various application areas.

• 신재생에너지
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• 제1권2호
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• pp.53-59
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• 2005

Objective of the research is to demonstrate solar thermal space and ground heating system which is integrated to a green-house culture facility for reducing healing cost, Increasing the value of product by environment control, and developing advanced culture technology by deploying solar thermal system. Field test for the demonstration was carried out in horticulture complex In Jeju Island. Medium scale solar hot water system was installed in a ground heating culture facility. Reliability and economic aspect of the system which was operated complementary with thermal storage and solar hot water generation were analyzed by investigating collector efficiency, operation performance, and control features. Short term day test on element performance and Long term test of the whole system were carried out. Optimum operating condition and its characteristics were closely Investigated by changing the control condition based on the temperature difference which Is the most important operating parameter For establishing more reliable and optimal design data regarding system scale and operation condition, continuous operation and monitoring on the system need to be further carried out. However, It is expected that, in high-insolation areas where large-scale ground storage is adaptable, solar system demonstrated in the research could be economically competitive and promisingly disseminate over various application areas.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2007년도 정기 학술대회 논문집
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• pp.151-156
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• 2007

Topology optimization has been widely used in many research areas due to its ability in providing intial designs for the problems with complex boundary conditions. This also has been useful in compliant mechanisms, but resulting layouts may not be immediately manufacturable because they usually consist of members with varying widths and shapes. Also, there occurs some numerical difficulties such as checkerboards or hinge patterns which result from 1-node connection, and intermediate values which make the manufacturing of the designed structure difficult. Though there are many remedies given to avoid this problems, they cannot be prevented. One may avoid this difficulty by employing uniform ground beams and explicit hinge joints. The proposed method is to connect uniform ground beams with elastic short-beam hinge joints. By choosing the widths of short beams as design variables, dominant deformations can occur mainly by flexible joints having intermediate widths. Unlike the conventional methods used for compliance minimization, intermediate widths must appear in compliant mechanism design problems. Also, the present approach does not encounter the problem of one-point hinges.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2011년도 춘계 학술논문 발표대회 1부
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• pp.127-130
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• 2011

The duplex waterproofing construction method has been investigated to improve various problems (how to fix the sheet, breaking, air/water pocket, and cracks caused by different materials) of the existing rooftop exposed waterproofing construction method. By using fiber sheet, Net PE fabric, and thixotropy urethane with high viscosity, the waterproofing construction method is to glue the ground and waterproof course by circular dot. The method is also to construct the waterproof course with high hardness by using waterproof membrane coatings in upper hybrid system. By gluing the ground and the waterproof course by circular dot, the study is expected to be useful to minimize the simultaneous breaking in the waterproof course as tensile stress is buffer in case of the ground crackling. Also, since the waterproofing construction method is good at moving and emitting vapor from the ground, it is considered to be effective to minimize any damages caused by air/water pocket and get loose of the waterproof course.

• 한국지반공학회논문집
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• 제36권1호
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• pp.5-15
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• 2020

말뚝의 동적거동은 말뚝과 지반 사이의 동적 상호작용에 큰 영향을 받는다. 특히, 경사지반에 설치된 말뚝은 진동방향에 따른 지반저항력 차이, 지반 변위 등에 의해 말뚝-지반 동적상호작용이 매우 복잡해진다. 본 연구에서는 건조 사질토 경사지반에 설치된 단일말뚝과 2×2 무리말뚝에 대하여 동적 원심모형실험을 수행하였다. 그리고, 말뚝과 지반 변위 사이의 위상차 및 동적 p-y 곡선 등을 산정하여 경사지반, 단일말뚝과 무리말뚝, 입력가속도 진폭 등의 조건이 말뚝-지반 동적 상호작용에 미치는 영향을 분석하였다. 그 결과, 지반-말뚝 사이의 운동학적 힘이 말뚝의 동적거동에 큰 영향을 주며, 동적 p-y 곡선이 지반경사, 잔류변위, 운동학적 힘의 영향 등으로 매우 복잡한 형상을 보여주는 것으로 나타났다.