• Smart Structures and Systems
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• 제13권4호
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• pp.659-683
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• 2014

The static analysis of structures with arbitrary cross-section geometry and material lamination via a refined one-dimensional (1D) approach is presented in this paper. Higher-order 1D models with a variable order of expansion for the displacement field are developed on the basis of Carrera Unified Formulation (CUF). Classical Euler-Bernoulli and Timoshenko beam theories are obtained as particular cases of the first-order model. Numerical results of displacement, strain and stress are provided by using the finite element method (FEM) along the longitudinal direction for different configurations in excellent agreement with three-dimensional (3D) finite element solutions. In particular, a layered thin-walled cylinder is considered as first assessment with a laminated conventional cross-section. An atherosclerotic plaque is introduced as a typical structure with arbitrary cross-section geometry and studied for both the homogeneous and nonhomogeneous material cases through the 1D variable kinematic models. The analyses highlight limitations of classical beam theories and the importance of higher-order terms in accurately detecting in-plane cross-section deformation without introducing additional numerical problems. Comparisons with 3D finite element solutions prove that 1D CUF provides remarkable three-dimensional accuracy in the analysis of even short and nonhomogeneous structures with arbitrary geometry through a significant reduction in computational cost.

• Wind and Structures
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• 제8권5호
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• pp.325-342
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• 2005

This paper deals with the buckling behavior of thin-walled aboveground tanks under wind load. In order to do that, the wind pressures are obtained by means of wind-tunnel experiments, while the structural non linear response is computed by means of a finite element discretization of the tank. Wind-tunnel models were constructed and tested to evaluate group effects in tandem configurations, i.e. one or two tanks shielding an instrumented tank. Pressures on the roof and on the cylindrical part were measured by pressure taps. The geometry of the target tank is similar in relative dimensions to typical tanks found in oil storage facilities, and several group configurations were tested with blocking tanks of different sizes and different separation between the target tank and those blocking it. The experimental results show changes in the pressure distributions around the circumference of the tank for half diameter spacing, with respect to an isolated tank with similar dimensions. Moreover, when the front tank of the tandem array has a height smaller than the target tank, increments in the windward pressures were measured. From the computational analysis, it seems that the additional stiffness provided by the roof prevents reductions in the buckling load for cases even when increments in pressures develop in the top region of the cylinder.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 제38회 하계학술대회
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• pp.1524-1525
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• 2007

A flexible tactile sensor module based on polyimide matrix integrated with sensing elements and pluggable terminals connector was fabricated by polymer micromachining technology for robotic applications. The tactile sensor arrays are composed of $4{\times}4$, $8{\times}8$ and $16{\times}16$ sensing elements connected with pluggable terminals connector, respectively. Especially, both the tactile sensor array and the pluggable terminals are formed in the sensor module during the fabrication process. The fabricated tactile sensor module is measured continuously in the normal force range of $0{\sim}1N$ with tactile sensor auto-evaluation system. The value of resistance is relatively increased linearly with normal force in the overall range. The variation rate of resistance is about 2.0%/N in the range of $0{\sim}0.6N$ and 1.5%/N in the range of $0.6{\sim}1N$. Also, the flexibility of the sensing module is adequate to be placed on any curved surface as cylinder because the matrix consists of polymer and metal thin film.

• International Journal of Aeronautical and Space Sciences
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• 제16권2호
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• pp.206-222
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• 2015

This work uses different finite element approaches to the free vibration analysis of reinforced shell structures, and a simplified model of a typical launcher with two boosters is used as an example. The results obtained using a refined one-dimensional (1D) beam model are compared to those obtained with commercial finite element software. The 1D models that are used in the present work are based on the Carrera Unified Formulation (CUF), which assumes a variable kinematic displacement field over the cross-sections of the beam. Two different sets of polynomials that correspond to Taylor (TE) or Lagrange (LE) expansions were used. The analyses focused on three reinforced structures: a stiffened panel, a reinforced cylinder and the complete structure of the launcher. The frequencies and natural modes obtained using one-dimensional models are compared to those obtained from classical finite element analysis. The classical FE models were built using a beam-shell or solid elements, and the results indicate that the refined beam models can in fact be used to investigate the behavior of very complex reinforced structures. These models can predict the shell-like modes that are typical of thin-walled structures that cannot be detected using classical beam models. The refined 1D models used in the present work provide results that are as accurate as those from solid FE models, but the 1D models have a much lower computational cost.

• 대한기계학회논문집B
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• 제38권8호
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• pp.671-676
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• 2014

볼텍스 컵은 실린콘 웨이프 제조공정과 같이 민갑한 물체을 이송시키는 방법으로 제안되었다. 볼테스 컵의 상부에 위치한 노즐을 통해 공기를 공급하면 내부 실린더에서 큰 선회유동이 생성된다. 공기는 볼텍스 컵과 바닥면 사이의 틈새로 빠져나가면서 흡입압력을 생성시키고 물체를 들어 올릴 수 있게 된다. 본 논문에서는 볼텍스 컵에 관한 3차원 유동 해석을 통해 실험 결과와 해석 결과를 비교하여 해석의 신뢰성을 확인하였다. 그리고 볼텍스 컵의 길이 변화와 형상 변화를 주어 해석을 통해 흡입 압력 생성에 영향을 미치는 정도를 분석하였고, 볼텍스 컵 형상의 최적 조건을 제시하였다.

• 대한기계학회논문집
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• 제16권4호
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• pp.621-629
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• 1992

본 연구에서는 Kelvin의 기본해와 초기응력 증분에 의해 정식화된 경계적분방 정식을 이용하여 점차적으로 외력을 증가시켰을 때, 선형등방경화재에 국부적으로 생 기는 항복영역과 항복하중, 탄소성 응력해석등을 재료비선형문제로 해석하였다. 이 때 초기응력 증분을 결정함에 있어서 종래에는 등가 소성변형률을 수렴판정으로 해석 하였지만, 이는 구분적인 선형 경화재와 온도 의존성 문제에는 적당하지 않으므로 암 기용일등은 등가응력과 응력-변형률 선도를 이용하여 수렴판정을 하였다. 그러나 이 방법은 소성역에서의 기울기가 변화하는 곳에서는 피할 수 없는 오차가 존재한다. 따라서 여기에서는 계산된 초기응력 증분에 의한 초기 탄성변형률에너지 증분과 응력 -변형률선도로 부터 구해지는 초기 탄성변형률에너지 증분을 이용한 수렴판정으로 초 기응력증분을 결정하였다. 또한, 내부영역적분을 일부 해석적인 적분과 수치적분을 병행한 경우와 전부 수치적분방법으로 내압을 받는 실린더와 단순 인장하중이 작용하 는 양편 Ⅴ형 노치를 갖는 박판의 경우에 적용하여 해석하였으며, 그 결과를 유한요소 법 프로그램인 NISA(numerically integrated elements for system analysis)로 구한 결과치와 비교, 고찰하였다.

• 대한임상검사과학회지
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• 제39권2호
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• pp.122-127
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• 2007

This study is a report about a specific patient whose primary stomach adenocarcinoma metastasized to uterine cervix adenocarcinoma. A thirty-nine year old female patient was initially diagnosed as having metastatic adenocarcinoma in the supraclavicular lymph node. Upon further examination, she was diagnosed with stomach adenocarcinoma. 8 months later, a cervix punch biopsy was performed. The stains used for examination were H&E stain, PAS stain, Alcian blue stain, Mucicarmine stain, Papanicolaou's (Pap.) stain, and as immunohistochemical stains, cytokeratin 7 and 20 were done. In the H&E stain, the tumor cells showed prominent and eccentric nuclei, thin nuclear membrane in abundant mucous cytoplasm, and cylinder shape. In the PAS stain, intracytoplasmic mucin vacuoles were stained with pink, and in Alcian blue and Mucicarmine stains, intracytoplasmic mucin vacuoles were stained with blue and red. As in the above results, she was diagnosed with undifferentiated adenocarcinoma. As found on the cytologic smear preparation of the uterine cervix stained by Papanicolaou's stains, the background was relatively clear, the number of malignant cells was relatively low, and large and eccentric nuclei in abundant cytoplasm were observed. Upon observing the tissue preparation of the uterine cervix biopsy by H&E stain, a clear background, large and eccentric nuclei, and a signet ring cell types were observed, and the number of malignant cells were fewer than in the primary uterine cervix adenocarcinoma. The vacuoles in cytoplasm were observed. The nuclear membrane and chromatin were thick and very rough, and upon observation by cytokeratin 7 and 20 of immunohistochemical stain, the tumor cells indicated a positive rate of 70% and 20%, respectively. According to these results, also she was diagnosed with metastasized uterine cervix adenocarcinoma. In summary of the results of pathologic findings on stomach biopsy and cytologic, histopathologic, and immunohistochemical finding on uterine cervix biopsy, the adenocarcinoma of her uterine cervix could assert the adenocarcinoma of signet ring cell type that was metastasized from the primary undifferentiated adenocarcinoma in stomach.

• Applied Microscopy
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• 제25권1호
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• pp.1-14
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• 1995

The purpose of this study was to investigate the main sensory trigeminal nucleus in the aging rat brain by means of electron microscope. Male Sprague-Dawley rats, two (control group) and thirty six (aging group) months of age, were used. These animals were sacrificed by perfusion fixation with 2.5% glutaraldehyde-2.0% paraformaldehyde (0.1M phosphate buffer, pH 7.4) under sodium pentobarbital. The objective area was punched out with a sharp-edged metal cylinder of 0.8 mm in diameter. These blocks of tissue were then washed in 0.1M phosphate buffer, postfixed in 2% osmium tetroxide, dehydrated in a graded series of ethyl alcohol, and embedded in Epon 812. Thin sections were cut with Super Nova ultramicrotome, pick up on grids and double stained with lead citrate and uranyl acetate, and observed in JEOL 100B electron microscope. The results were as follows: 1. In the control group, the neuronal cell body of the main sensory trigeminal nucleus was filled with nucleus, Golgi complex, Nissl substance, mitochondria, microfilaments and microtubules. However, few Nissl substances are seen in neuronal cell body. Axoaxonic synapse, axodendritic synapse, axosomatic synapse, axospinous synapse, myelinated and unmyelinated nerve fibers were well organized around cell bodies. Neurons with abnormal changes were not seen. 2. In the aging group, the neuronal cell body of the main sensory trigeminal nucleus contained large number of lipofuscin granules, dense body and swollen mitochondria. Terminal boutons contained glycogen, crystal-like vesicle and membranous indicating first signs of degeneration. The dendrites were found to be in synaptic contact with altered axon terminals. Frequently axons filled with dark axoplasn and splitted myelin sheath were noticed.

• 전산구조공학
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• 제9권3호
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• pp.199-207
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• 1996

원통관에 휨모멘트가 작용하면 변형후 단면은 타원형상을 갖게된다. 단면의 타원화에 의해 단면이 감소하게 되면 휨강성이 감소하게 되며, 따라서, 휨모멘트-곡률관계가 하중점감형으로 된다. 이 휨강성의 감소현상을 Brazier이론 또는 Brazier현상이라고 한다. 적층평판에 있어서도 각층의 재료상수가 뚜렷하게 다른 경우 원통관에서의 Brazier현상과 유사한 현상이 발생한다. 본 논문에서는 평판에서의 Brazier현상을 규명하기 위하여 3층 적층모델을 만들어 각층의 재료정수가 현저히 다른 경우 어떠한 현상이 일어나는 가를 실험적으로 규명하였고, 이론해석을 위하여 스프링모델을 사용하였다. 본 논문의 모델에서 알 수 있듯이 중간층의 재료상수가 상하층 요소의 재료상수 보다 뚜렷하게 작은 경우 중간층의 거동이 현저히 크게됨을 알 수 있었다. 즉, 본 논문에서 채택한 모델의 경우에 있어서도 원통관에서 일어나는 Brazier형상이 일어나고 있음이 실험적 그리고 해석적으로 규명되었다 .

• Applied Biological Chemistry
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• 제29권3호
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• pp.241-247
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• 1986

쌀밥 품질의 영향 요인을 규명하기 위하여 밥 짓기 과정중 밥과 밥물의 상호 관계를 분석하고, 저급의 장립종 밀양 23호의 밥맛 증진의 수단으로 새로운 밥짓기 방법을 제시하였다. 밥짓기 과정중 밥과 밥물의 높이 변화를 측정하였다. 끊는점 부근에서 밥물이 급격히 감소하고, 이어서 농축된 밥물이 밥알 표면에 엷은 피막층을 형성함을 관찰할 수 있었다. 피막 보강 물질로 찹쌀분 1,2%(W/W)를 첨가 한 후 밥짓기를 향한 결과, 피막이 크게 보강되었으며 이렇게 제조된 밥은 윤기와 외관이 향상되고 수분 함량이 증가하였으며 밥짓기중 가용성 쌀 고용분 함량의 용출을 감소시킬 수 있었다. 밥알 피막의 형성은 밥짓기의 최종단계에서 밥알의 진동과 밥물의 고형분 농도와 유관함을 보였고, 밥의 음질 결정의 중요 요소로 작용할 수 있음을 제안하였다.