• 지질공학
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• 제1권1호
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• pp.68-84
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• 1991

A numerical analysis using Universal Distinct Element Code program for the nuclear waste disposal cavern has been performed for a typical Korean crystalline rock condition with same geometry of Swedish low and intermediate nuclear waste disposal repository(S.F.R). The stress concentration, displacement and safety factor for the typical single cross section of cavern, 5 caverns and a silo are analyzed.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 1997년도 추계학술대회 논문집
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• pp.114-119
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• 1997

Natural vibration of the rotor system having multi-step cross-sections is analyzed. The rotary inertia and the shear deformation are considered. Torque is also included in order to simulate the power transmission system. The complex displacement and the variable separation are introduced. The exact solutions in uniform cross-section segment and the boundary conditions are used. Natural frequencies and mode shapes are obtained, especially the mode shapes are countinuous.

• 한국지진공학회논문집
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• 제3권1호
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• pp.41-54
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• 1999

비대칭 박벽단면을 갖는 곡선보의 자유진동해석을 수행할 수 있는 유한요소 이론 및 엄밀해를 제시하기 위하여 가상일의 원리를 이용한 3차원 연속체의 운동방정식을 제시한다 박벽단면의 구속된 비틂효과를 고려하는 박벽 곡선보의 변위장을 도입하고 이를 연소체의 운동방정식에 대입하여 단면에 대해 적분함으로써 박벽 곡선보의 운동방정식을 유도한다. 단순지지되고 일축대칭단면을 갖는 박벽 곡선보의 면내 자유진동 모드에 대응하는엄밀해를 산정하였으며 곡선보를 유한요소로 분할하여 요소의 변위장을 요소 변위벡터에 관한 3차의 Hermitian 다항식으로 나타내고 이를 운동방정식에 대입함으로써 탄성강도행렬과 질량 행렬을 유도한다 또한 본 연구에서 얻어진 엄밀해와 곡선보요소를 이용한 유한요소 해석결과를 직선보요소 및 ABAQUS의 쉘요소를 이용하여 얻어진 결과와 비교 검토를 함으로써 본 연구의 타당성을 입증한다.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제52권12호
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• pp.545-552
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• 2003

When a Si PIN diode is exposed to fast neutrons, it results in displacement damage to the Si lattice structure of the diode. Defects induced from structural dislocation become effective recombination centers for carriers which pass through the base of a PIN diode. Hence, increasing the resistivity of the diode decreases the current for the applied forward voltage. This paper involves the development of a neutron sensor based on the phenomena of the displacement effect damaged by neutron exposure. The neutron effect on the semiconductor was analyzed. Several PIN diode arrays with various thickness and cross-section area of the intrinsic layer(I layer) were fabricated. Under irradiation tests with a neutron beam, the manufactured diodes have a good linearity to neutron dose and show that the increase of thickness of I layer and the decrease of cross-section of PIN diodes improve the sensitivity. Newly developed PIN diodes with thicker I layer and various cross section, were retested and then showed the best neutron sensitivity at the condition that the I layer thickness was similar to a side length. On the basis of two test results, final discrete PIN diodes with a rectangular shape were manufactured and the characteristics as neutron detectors were analyzed through the neutron beam test using on-line electronic dosimetry system. Developed PIN diode shows a good linearity as dosimetry in the range of 0 to 1,000cGy(Tissue) and its neutron sensitivity is 13mV/cGy at constant current of 5mA, that is three times higher than that of commercially available neutron detectors. And the device shows little dependency on the orientation of the neutron beam and a considerable stability in annealing test for a long period.

• 한국공간구조학회논문집
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• 제5권4호
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• pp.101-108
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• 2005

고층건물의 진동응답을 저감시키기 위한 다양한 방법들이 연구되고 있다. 이들 진동응답의 저감 연구는 건물의 외관을 병화 시키는 방법과 건물에 부가감쇠장치를 설치하는 방법들이 있는데 본 논문에서는 고층 건물의 형태의 변화에 다른 진동변위응답의 특성을 파악하고자 한다. 고층건물의 형태변화 중에서도 외관에 테이퍼를 수는 방법을 사용하였다. 기류의 특성은 도심 및 교외지역을 중심으로 풍동실험을 실시하였다.

• Journal of the Optical Society of Korea
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• 제20권5호
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• pp.601-606
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• 2016

In this study, in order to analyze the low-temperature sintering process of silver and copper nanoparticles, we calculate their melting temperatures and surface melting temperatures with respect to particle size. For this calculation, we introduce the concept of mean-squared displacement of the atom proposed by Shi (1994). Using a parameter defined by the vibrational component of melting entropy, we readily obtained the surface and bulk melting temperatures of copper and silver nanoparticles. We also calculated the absorption cross-section of nanoparticles for variation in the wavelength of light. By using the calculated absorption cross-section of the nanoparticles at the melting temperature, we obtained the laser threshold energy for the sintering process with respect to particle size and wavelength of laser. We found that the absorption cross-section of silver nanoparticles has a resonant peak at a wavelength of close to 350 nm, yielding the lowest threshold energy. We calculated the intensity distribution around the nanoparticles using the finite-difference time-domain method and confirmed the resonant excitation of silver nanoparticles near the wavelength of the resonant peak.

• 한국구조물진단유지관리공학회 논문집
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• 제24권6호
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• pp.59-66
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• 2020

축소모형 팔각형 기둥 실험체 2개를 제작하여 일정한 축력 하에서 반복 횡하중을 가력하는 실험을 수행하였다. 실험체는 중실단면과 중공단면이고 모든 실험체의 횡방향 나선철근 체적비는 0.00206의 값을 갖는다. 실험체들은 휨-전단 파괴거동을 보였다. 본 논문에서는 실험결과에 따른 파괴거동과 내진성능을 분석하였다. 실험결과, 중공 실험체는 초기강성, 초기 균열양상, 에너지 소산능력 등의 구조성능이 중실 실험체와 유사한 거동을 보였으나, 중공 실험체의 경우에는 3% 변위비 이후에 횡력, 극한변위, 에너지소산능력이 현저하게 감소되었다.

• 대한건축학회논문집:구조계
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• 제35권7호
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• pp.171-178
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• 2019

Auto Climbing Formwork System (ACS) for construction of high-rise building is a construction method for automatically lifting the formwork system supported by the anchor on the pre-constructed concrete wall. It has excellent construction speed and quality, but it has the possibility of structural failure depending on the quality of concrete and also has low economical efficiency due to the use of foreign technology. In order to overcome these problems, this study conducted an optimum design for the development of a new concept of Corner Supported Auto Climbing System (CS-ACS) in conjunction with the development of corner steel-reinforced concrete core wall system. For the design the formwork system, the basic module and structural member compositions were planned, and the structural analysis program was used to analyze the optimum member's cross section and spacing. As a result, the horizontal displacement and the stress of the horizontal members were influenced by the spacing more than the cross-section of the member. On the other hand, vertical members did not affect the displacement and stress of the formwork system. The form tie was very effective in controlling the displacement when adjusting the spacing of the horizontal members, but when the spacing of the form tie is more than 1,500mm, it is analyzed that form tie is yielding in basic module. When the span of the formwork system is more than 30m, it is analyzed that the basic module needs to be changed because of the increase of overall displacement.

• Structural Engineering and Mechanics
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• 제84권3호
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• pp.423-435
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• 2022

In this article, we present torsion-bending analysis of a composite FGM beam with an open section, according to the advanced and refined theory of 1D / 3D beams based on the 3D Saint-Venant's solution and taking into account the edge effects. The (initially one-dimensional) model contains a set of three-dimensional (3D) displacement modes of the cross section, reflecting its 3D mechanical behaviour. The modes are taken into account depending on the mechanical characteristics and the geometrical form of the cross-section of the composite FGM beam. The model considered is implemented on the CSB (Cross-Section and Beam Analysis) software package. It is based on the RBT/SV theory (Refined Beam Theory on Saint-Venant principle) of FGM beams. The mechanical and physical characteristics of the FGM beam continuously vary, depending on a power-law distribution, across the thickness of the beam. We compare the numerical results obtained by the three-beam theories, namely: The Classical Beam Theory of Saint-Venant (Classical Beam Theory CBT), the theory of refined beams (Refined Beam Theory RBT), and the theory of refined beams, using the higher (high) modes of distortion of the cross-section (Refined Beam Theory using distorted modes RBTd). The results obtained confirm a clear difference between those obtained by the three models at the level of the supports. Further from the support, the results of RBT and RBTd are of the same order, whereas those of CBT remains far from those of higher-order theories. The 3D stresses, strains and displacements, obtained by the present study, reflect the 3D behaviour of FGM beams well, despite the initially 1D nature of the problem. A validation example also shows a very good agreement of the proposed models with other models (classical or higher-order beam theory) and Carrera Unified Formulation 1D-beam model with Lagrange Expansion functions (CUF-LE).

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2006년도 정기 학술대회 논문집
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• pp.10-14
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• 2006

FBG sensors are able to measure the strain of structures more easily and durable than electronic resistance gages and thus many researches are on the way to apply the FBG sensor for response monitering of infrastructures. This study investigates the deflection estimation technique using FBG sensors. Several FBG sensors are multiplexed in single optical fiber and installed. in parallel pairs along the length of the structure. The measured strains at the top and bottom of a cross section can be transferred to the curvature of the section which can be used to calculate its displacement. It has been demonstrated that the estimated deflections using the FBG sensor are compared well with the readings from displacement transducers. The results show that the proposed instrumentation technique is capable of estimating the vertical deflection of the structures for various loading conditions including impact and dynamic loads, which is crucial in the structural health monitoring.