• Geomechanics and Engineering
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• 제14권4호
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• pp.337-344
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• 2018

The study of the mining effect influenced by a normal fault has great significance concerning the prediction and prevention of fault rock burst. According to the occurrence condition of a normal fault, the stress evolution of the working face and fault plane, the movement characteristics of overlying strata, and the law of fault slipping when the working face advances from footwall to hanging wall are studied utilizing UDEC numerical simulation. Then the inducing-mechanism of fault rock burst is revealed. Results show that in pre-mining, the in situ stress distribution of two fault walls in the fault-affected zone is notably different. When the working face mines in the footwall, the abutment stress distributes in a "double peak" pattern. The ratio of shear stress to normal stress and the fault slipping have the obvious spatial and temporal characteristics because they vary gradually from the higher layer to the lower one orderly. The variation of roof subsidence is in S-shape which includes slow deformation, violent slipping, deformation induced by the hanging wall strata rotation, and movement stability. The simulation results are verified via several engineering cases of fault rock burst. Moreover, it can provide a reference for prevention and control of rock burst in a fault-affected zone under similar conditions.

• 대한조선학회논문집
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• 제29권1호
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• pp.158-172
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• 1992

대형구조물의 국부구조계를 구성하는 후판, 선체이중저구조와 같은 복판팬널등의 진동문제에 있어서 전단변형 및 회전관성효과가 매우 크므로 정확한 진동해석을 위해서는 이들 구조계를 상기 효과를 고려한 Mindlin판유추 구조계로 취급하여야 한다. 또한, 이들 구조계의 실제 경계조건은 일반적으로 단순지지와 고정의 중간상태이므로 경계조건을 회전에 대한 탄성구속으로 다룰 필요가 있다. 그러나 4변모두 단순지지 경계조건을 갖는 Mindlin판을 제외하고는 엄밀해를 구하기 어려워 근사적 방법의 사용이 불가피한데, 한 방법으로 Rayleigh-Ritz 방법이 널리 이용된다. Rayleigh-Ritz 방법에 의한 Mindlin판유추 구조계의 진동해석에 있어서 진동파형가정함수로서 통상 Timoshenko보함수가 이용된다. 이 경우 전단변형의 효과가 고려되어야 하므로 횡방향처짐 및 굽힘회전각에 대한 2개의 함수계가 도입되어야 하므로 실제 연산이 Euler보함수를 이용한 박판유추 구조계의 진동해석 때 보다도 훨씬 더 복잡하다. 따라서, 본 논문에서는 이러한 연산의 복잡성을 줄이기 위해 진동파형가정함수로서 Timoshenko보함수 성질을 갖는 다항식 도출방안을 제시하였고, 이를 이용하여 주변경계조건이 회전에 대해 탄성구속된 Mindlin판유추 구조계의 진동해석 및 감도해석을 정식화하여, 등방성 후판 및 실선이중저구조의 1/8축척 모델을 대상으로 일련의 수치계산을 수행하여 이의 정확도 및 효율성을 검증하였다.

• 대한한의학회지
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• 제28권1호통권69호
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• pp.11-24
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• 2007

Objectives : Hemiplegic shoulder pain is one of the common sequelae of stroke. Although many different methods of treatment are applied, none have yet been proved to be effective. In this study we assessed the effectiveness of bee venom in patients with shoulder pain after stroke. Methods : This study was a double blinded, randomized, placebo-controlled clinical trial. All subjects received either 0.6 ml bee venom injection (venom:saline = 1:10000) or 0.6ml physiological saline solution (placebo) at three acupoints. The effectiveness was assessed by visual analogue scale, pain rating score, Fugl-Meyer assessment and passive external rotation. Results : There were 24 patients in the venom group and 22 patients in the placebo group. The venom group5,hewed more effectiveness in VAS and PRS than the placebo group. Conclusions : This study suggests that bee venom injection has significant analgesic effect on hemiplegic shoulder pain. Further study based on multi-centers, larger population, and long term 1311ow-up is needed to confirm this suggestion.

• 문화기술의 융합
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• 제6권1호
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• pp.515-520
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• 2020

본 연구에서는 4절 평행 링크의 설계와 실제 구현에 대한 것으로 평행 4절 링크는 한축의 회전을 다른 축의 회전 운동으로 전달하기 위한 기본적인 기구학적 메카니즘으로 널리 이용되고 있다. 그런데 평행 4절 링크는 운동 도중에 전환점에서 위상 역전이 발생하는 문제가 발생하여 실제 구현에서는 이를 고려하여 설계하여야 한다. 링크 역전을 방지하기 위해서는 추가적인 위상 역전 억제용 링크를 옵셋을 두어 붙이는 2중 평행 사변형 형태의 링크를 제작하면 되는 것으로 일부 알려져 있으나 실제 제작하여 실험한 결과 전환점에서 운동이 부드럽지 않은 현상이 발생하였다. 본 연구에서는 이 문제를 해결하기 위해 위상 역전 방지를 위한 옵셋을 주는 링크외에 보조적으로 평활한 운동을 위한 링크를 추가시켜 피동축이 구동축을 따라 회전할 때에 특정지점에서 위상 역전이 발생하지 않고 평활한 운동을 수행하는 것을 확인 할 수 있었다.

• 대한조선학회지
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• 제13권4호
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• pp.19-24
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• 1976

Some method of analysis of rectangular plates under distributed load of various intensity with all edges built in are presented in. Analysis of many structures such as bottom, side shell, and deck plate of ship hull, and flat slab, deck systems of bridges is a problem of plate with continuous supports or clamped edges. When the four edges of rectangular plate is simply supported, the double fourier series solution developed by Navier can represent an exact result of this problem. If two opposite edges are simply supported, Levy's method is available to give an "exact" solution. When the loading condition and boundary condition of a plate does not fall into these cases, no simple analytic method seems to be feasible. Analysis of a plate under distributed loads of various intensity with all edges built in is carried out by applying Navier solution and Levy's method as well as "Principle of Superposition" In discussing this problem we start with the solution of the problem for a simply supported rectangular plate and superpose on the deflection of such a plate the deflections of the plate by slopes distributed along the all edges. These slopes we adjust in such a manner as to satisfy the condition of no rotation at the boundary of the clamped plate. This method can be applied for the cases of plates under irregularly distributed loads of various intensity with two opposite edges simply supported and the other two edges clamped and all edges simply supported and this method can also be used to solve the influence values of deflection, moment and etc. at arbitrary position of plates under the live load.

• Nuclear Engineering and Technology
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• 제55권2호
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• pp.595-602
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• 2023

The EAST ICRF system operating space has been extended in power and phase control with a low-level RF system for the new double-strap antenna. Then the multi-step power and periodic phase scanning experiment were conducted in L-mode plasma, respectively. In the power scanning experiment, the stored energy, radiation power, plasma impedance and the antenna's temperature all have positive responses during the short ramp-ups of P_L;ICRF. The core ion temperature increased from 1 keV to 1.5 keV and the core heating area expanded from |Z| ≤ 5 cm to |Z| ≤ 10 cm during the injection of ICRF waves. In the phasing scanning experiment, in addition to the same conclusions as the previous relatively phasing scanning experiment, the superposition effect of the fluctuation of stored energy, radiation power and neutron yield caused by phasing change with dual antenna, resulting in the amplitude and phase shift, was also observed. The active control of RF output facilitates the precise control of plasma profiles and greatly benefits future experimental exploration.

• 한국압력기기공학회 논문집
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• 제18권1호
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• pp.19-25
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• 2022

Nuclear Power Plants (NPP) should be designed to have sufficient safety margins and to ensure seismic safety against earthquake that may occur during the plant life time. After the 9.12 Gyeongju earthquake accident, the structural integrity of nuclear power plants due to the beyond design basis earthquake is one of key safety issues. Accordingly, it is necessary to conduct structural integrity evaluations for domestic NPPs under beyond design basis earthquake. In this study, the Level 3 LBB (Leak Before Break) evaluation was performed by considering the beyond design basis earthquake for the surge line of a OPR1000 plant of which design basis earthquake was set to be 0.2g. The beyond design basis earthquake corresponding to peak ground acceleration 0.4g at the maximum stress point of the surge line was considered. It was confirmed that the moment behaviors of the hot leg and pressurized surge nozzle were lower than the maximum allowable loading in moment-rotation curve. It was also confirmed that the LBB margin could be secured by comparing the LBB margin through the Level 2 method. It was judged that the margin was secured by reducing the load generated through the compliance of the pipe.

• Geomechanics and Engineering
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• 제31권1호
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• pp.1-14
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• 2022

Urban deep excavation will affect greatly on the deformation of adjacent existing buildings, especially those with shallow foundations. Isolation piles has been widely used in engineering to control the deformation of buildings adjacent to the excavation, but its applicability is still controversial. Based on a typical engineering, numerical calculation models were established and verified through monitoring data to study the influence characteristics of isolation piles on the deformation of existing shallow foundation buildings. Results reveal that adjacent buildings will increase building settlement δ_v and the deformation of diaphragm walls δ_h, while the isolation piles can effectively decrease these. The surface settlement curve is changed from "groove" type to "double groove" type. Sufficiently long isolation pile can effectively decrease δ_v, while short isolation piles will lead to a negative effect. When the building is within the range of the maximum settlement location P, maximum building rotation θ_m will increase with the pile length L and the relative position between isolation pile and building d/D increase (d is the distance between piles and diaphragm walls, D is the distance between buildings and diaphragm walls), instead, θ_m will decrease for buildings outside the location P, and the optimum was obtained when d/D=0.7.

• Earthquakes and Structures
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• 제26권3호
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• pp.203-218
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• 2024

Beam-column joints in the frame structure are at high risk of brittle shear failure which would lead to significant residual deformation and even the collapse of the structure during an earthquake. In order to improve the damage issue and enhance the recoverability of the beam-column joints, a sector lead rubber damper (SLRD) has been developed. The SLRD can increase the bearing capacity and energy dissipation capacity, and also demonstrating recoverability of seismic performance following cyclic loading. In this paper, the hysteretic behavior of SLRD was experimentally investigated in terms of the regular hysteretic behavior, large deformation behavior and fatigue behavior. Furthermore, a parametric analysis was performed to study the influence of the primary design parameters on the hysteretic behavior of SLRD. The results show that SLRD resist the exerted loading through the shear capacity of both rubber parts coupled with the lead cores in the pre-yielding stage of lead cores. In the post-yielding phase, it is only the rubber parts of the SLRD that provide the shear capacity while the lead cores primarily dissipate the energy through shear deformation. The SLRD possesses a robust capacity for large deformation and can sustain hysteretic behavior when subjected to a loading rotation angle of 1/7 (equivalent to 200% shear strain of the rubber component). Furthermore, it demonstrates excellent fatigue resistance, with a degradation of critical behavior indices by no more than 15% in comparison to initial values even after 30 cycles. As for the designing practice of SLRD, it is recommended to adopt the double lead core scheme, along with a rubber material having the lowest possible shear modulus while meeting the desired bearing capacity and a thickness ratio of 0.4 to 0.5 for the thin steel plate.

• 한국석유지질학회지
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• 제2권2호
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• pp.51-57
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• 1994

1969년 미해군이 황해지역에서 실시한 항공자력측정자료를 분석 연구한 결과, 한국 서남근해 제2광구 내에 있는 기존 군산분지(群山盆地) 남쪽에 흑산분지(黑山盆地)라고 명명하는 신퇴적분지가 존재함을 알게 되었다. 이 흑산분지는 서서 북-남남동으로 뻗은 3개의 소분지로 구성되었다. 이번 연구결과로 인하여 군산분지에 대해 독립적인 새로운 분석을 하게 했고 또한 그 두 분지뿐만 아니라 서근해 전역에 걸쳐 지질구조적 성인 및 그 생성역학(生成力學)에 대한 중요한 자료를 얻게 되었다. 분지생성 및 구조형태는 ‘두번-건너뛴-좌수향-렌치단층(斷層)’(Double overstepped left-lateral wrench faults)에 의한 롬보캐즘(rhombochasm)으로 해석된다. 한반도 내에 발달하고 있는 대단층들을 본 항공자력이상으로부터 얻은 중거에 의해서 본 연구지역 즉 근해까지 연장시켰다. 또한 이들 단층들의 성질을 좌수향렌치로 해석했다. 이와 같은 전 지역적인 단층 구조형태는 이동우의 영동분지에 대한 연구결과와 같다. 단층들의 운동방향은 필리핀이 에오세(Eocene) 이후 시계방향으로 약$80^{\circ}$회전했다는 최근 발표된 고지자기연구(古地磁氣硏究)에서 얻은 증거에 의하여 뒷받침되고 있다. 2$\frac{1}{2}$-차원의 모형 연구결과에 의하면 군산분지는 대략 $7,500{\cal}m$의 두터운 퇴적층을 갖는 것 같다. 흑산분지는 그 상부에 탄성파 속도가 빠른 층이 덮고 있어서 지금까지 발견되지 않고 있었다고 믿어진다. 흑산분지의 개략적인 형태가 석유부존에 적합한 듯 하기 때문에 두터운 퇴적층을 보유하고 있는 듯한 자력적 표현을 규명하기 위한 정밀항공 자력탐사를 실시할 것을 추천한다. 만약 고속도의 층이 확인된다면 자력탐사법에 대한 보충이 될 뿐 아니라 퇴적층에 대한 구조적인 묘사를 하는데 도움이 되는 중력탐사를 추가할 것을 추천한다. 정밀자력탐사 또는 중력탐사를 할 수 없다면 높은 에너지원의 탄성파 탐사를 실시하는 것이 더 효과적일 수도 있다.