• 한국전기전자재료학회논문지
• /
• 제11권11호
• /
• pp.954-962
• /
• 1998

Energy-trapped thickness vibrations of piezoelectric substrates are utilized in fabricating resonators and filters which have their operating frequencies in HF band. Normalized particle displacement distributions of the fundamental thickness shear vibration mode and overtone modes into the thickness direction in energy-trapped resonators and double-coupled filters were obtained by solving the wave equation and calculating the solved equations. These results show that as the number order of the harmonic mode in a energy-trapped resonator becomes larger, the degree of energy-trapping in the resonator increase, and if the conditions for energy-trapping become sufficiently weak, the energy-trapping effect of the harmonic mode which has the lower order disappears the earlier. Above simulation results were proved by the experiments.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2001년도 추계학술대회논문집B
• /
• pp.493-498
• /
• 2001

In the low velocity displacement air-conditioning system, the conditioned air is supplied from the diffuser placed on the wall near the floor and vented near the ceiling. This system has some advantages upon the traditional mixing system; the air quality near the people is improved by the displacing action of the system and the energy may be saved by neglecting the cooling or heating load for the upper space of the space above the people. This study is to examine the temperature and velocity distributions in the room and near the diffuser. It is found that the temperature is stratified uniformly all over the room space to show the displacing function of the system.

• Earthquakes and Structures
• /
• 제13권3호
• /
• pp.241-253
• /
• 2017

In this paper, dynamic response of the horizontal nanofiber reinforced polymer (NFRP) strengthened concrete beam subjected to seismic ground excitation is investigated. The concrete beam is modeled using hyperbolic shear deformation beam theory (HSDBT) and the mathematical formulation is applied to determine the governing equations of the structure. Distribution type and agglomeration effects of carbon nanofibers are considered by Mori-Tanaka model. Using the nonlinear strain-displacement relations, stress-strain relations and Hamilton's principle (virtual work method), the governing equations are derived. To obtain the dynamic response of the structure, harmonic differential quadrature method (HDQM) along with Newmark method is applied. The aim of this study is to investigate the effect of NFRP layer, geometrical parameters of beam, volume fraction and agglomeration of nanofibers and boundary conditions on the dynamic response of the structure. The results indicated that applied NFRP layer decreases the maximum dynamic displacement of the structure up to 91 percent. In addition, using nanofibers as reinforcement leads a 35 percent reduction in the maximum dynamic displacement of the structure.

• The Journal of Korean Physical Therapy
• /
• 제22권1호
• /
• pp.47-51
• /
• 2010

Purpose: The purpose of this study was to determine whether there are any differences, with and without a toe spreader (TS), in dynamic foot pressure distribution in children with spastic diplegic cerebral palsy. Methods: Dynamic foot pressure recording using the RSscan system were obtained during walking in 12 participants (male=7, female=5) with and without TS. Mean force was measured for four different plantar regions; great toe, forefoot, midfoot, hindfoot. Displacement of center of pressure (COP), velocity of COP displacement and stance time were also measured during gait. Results: TS walking exhibited statistically significant decrease of mean force under great toe and forefoot (p<0.05), compared with a barefoot walking. Also, TS walking exhibited statistically significant increase of antero-posterior displacement of COP (p>0.05). Conclusion: These findings indicate the potential clinical utility of toe spreader to correct dynamic foot pressure during stance phase in children with spastic diplegic cerebral palsy.

• 대한기계학회논문집A
• /
• 제27권2호
• /
• pp.223-230
• /
• 2003

Stress patterns are created in the plastic spur gear tooth body by introducing a hole or a steel pin to improve stress distribution. Static analysis using finite element method is carried out to show the effect. The result shows that maximum stress as well as tooth tip displacement is dependent on the size and location of a hole or a steel pin. When a hole located on the tooth center line, the maximum static stress level and the tooth tip deflection is always higher than that of a solid gear. But, a considerable reduction in the maximum stress and tooth tip displacement is achieved by insertion of steel pin.

• EDISON SW 활용 경진대회 논문집
• /
• 제4회(2015년)
• /
• pp.217-222
• /
• 2015

In this paper, a study was conducted for the optimization through shear web of shape the Edison program in wind power blade. We measured the displacement and stress distribution through two optimization methods to select the model with the smallest displacement and stress values. Before running the analysis, We try to find the inflection point through the shear web of the model and then analyze by introducing the geometric nonlinearity. The first optimization variables are introduced by the pitch angle and three web shapes. Third model such a honeycomb structure is good way to get an advantage for bending test. According to a method of previous optimization, third model is chosen and then the thickness of the web and blade as a variable is introduced, it is extracted as a result of displacement and the maximum stress per mass.

• 대한기계학회논문집
• /
• 제19권1호
• /
• pp.240-250
• /
• 1995

A CPM (computational preston tube method) was developed to measure wall shear stress in a transitional boundary layer on a flat plate using Preston tubes. Correlation for the displacement factor of Preston tubes was improved for a CPM to be used in the transitional boundary layer. The distribution of skin-friction coefficient was reasonably predicted in the uniform free stream of 3.1% turbulence intensity. Reasonable and accurate estimation of displacement factor of Preston tubes was found to be of crucial importance for the CPM, especially in the laminar boundary layer. The mean velocity profiles of the boundary layer on the plate were also measured and presented.

• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 2005년도 봄학술 발표회 논문집(I)
• /
• pp.107-110
• /
• 2005

In general, post tensioned (PT) flat plate slab systems have been used as a Gravity Load Resisting System (GLRS) in buildings. Thus, these systems should be constructed with Lateral Force Resisting Systems (LFRS) such as shear walls and moment resisting frames. When lateral loads such as winds or earthquakes occur, lateral load resisting systems undergo displacement by which connected gravity systems experience lateral displacement. Therefore, GLRS should have some lateral displacement capacity in order to hold gravity loads under severe earthquakes and winds. Since there are the limited number of researches on PT flat plate slab systems, the behavior of the systems have not been well defined. This study investigated the cyclic behavior of post tensioned flat plate slab systems. For this purpose, an experimental test was carried out using 4 interior PT flat plate slab-column specimens. All specimens have bottom reinforcement in the slab around the slab-column connection. Test variables of this experimental study are vertical load level and tendon distribution patterns.

• 대한의용생체공학회:학술대회논문집
• /
• 대한의용생체공학회 1993년도 추계학술대회
• /
• pp.99-103
• /
• 1993

A monoleaflet polymer artificial heart valve which showed the remarkable improvement in pressure drop compared with other types of artificial valve was designed to decrease the deflection in vertical direction and the displacement or the valve tip in horizontal direction. Stress distribution change was studied as the location of the supporting members or the valve frame changed. And it was found that using the valve tip horizontal displacement the minimum valve thickness could be obtained in order to prevent the gap between the valve tip and the frame wall.

• Journal of the Korean Society for Industrial and Applied Mathematics
• /
• 제24권3호
• /
• pp.293-303
• /
• 2020

The present work aims to analyzed the transient thermoelastic stress analysis of a thin circular plate with uniform internal heat generation. Initially, the plate is characterized by a parabolic temperature distribution along the z-direction given by T = T₀(r, z) and perfectly insulated at the ends z = 0 and z = h. For times t > 0, the surface r = a is subjected to convection heat transfer with convection coefficient h_c and fluid temperature T_∞. The integral transform method used to obtain the analytical solution for temperature, displacement, and thermal stresses. The associated thermoelastic field is analyzed by making use of the temperature and thermoelastic displacement potential function. Numerical results are carried out with the help of computational software PTC Mathcad Prime-3.1 and shown in figures.