• Structural Engineering and Mechanics
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• 제16권1호
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• pp.101-114
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• 2003

A base isolation system is proposed for earthquake protection of structures. The system incorporates spherical supports for the base, a specially designed spring-cam system to keep the base rigidly supported under normal condition and to allow it to move for the duration of the earthquake under the constraint of a spring with optimized non-linear characteristics. A single-story model is constructed to investigate the feasibility of the concept. Numerical simulations of the system as well as experimental results show that 95% reduction of the transmitted force to the structure can be achieved. To demonstrate the effectiveness of this isolation mechanism, the maximum dynamic bending stress developed at predetermined critical points within the frame of the structure is measured. Significant reduction of the dynamic stresses is obtained.

• 소성∙가공
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• 제24권6호
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• pp.387-394
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• 2015

Air springs are designed to support loads using the volume elasticity in a cylindrical shaped air bag made of a composite material with a rubber matrix and two plies of reinforced fibers. Recently, applications of these springs have been expanded from railway vehicles to passenger cars. The current study presents a finite element analysis of a manufactured air spring for a passenger car. The analysis was conducted including the mounting steps of the air bag using a static loading condition. A method for controlling the internal pressure and displacements during the mounting step was developed. The characteristic load curve and the shape of the air bag were in good agreement with the experimental data with respect to the design height, the bump height and the rebound height. Results indicate that ply angles of fibers vary from 38 degrees to 56 degrees during static loading.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2003년도 추계학술대회논문집
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• pp.345-349
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• 2003

The dynamic behavior of CANDU nuclear fuel channel was analyzed by the use of 3-dimensional finite element method, under the various fault conditions such as a fault in the end fitting support and the removal/migration of the garter spring in the fuel channel, in order to predict the dynamic behavior for a degraded symptoms of CANDU nuclear fuel channel. Moreover, the frequency response analysis for possible fault conditions was also peformed considering the effects of the pressure tube vibration and flow-induced vibration by the coolant flow. From the analysis of the frequency responses, defects in the garter spring have influenced the changes of 2nd and 3rd modes and all the important modes are varied for the failure in the journal bearing in the end fitting body.

• Selected Papers of The Society of Naval Architects of Korea
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• 제1권1호
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• pp.52-64
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• 1993

There exist many frame structural systems having some attachments reducible to damped spring-mass systems, concentracted masses and spring supports. For free and forced vibration analyses of such a system an analytical method based on the receptance method is presented. A framed structure having attachments is considered as a combined system composed of various Timoshenko beam and bar elements and the attachments. So, the vibration characteristics of the system are calculated by synthesizing receptances and Support Displacement Transfer Ratio (SDTR) of beam and bar elements In spectral and/or closed forms, and receptances of the attachments. In forced vibration analysis, arbitrary excitation forces at a point on the structure and displacement excitations at boundaries are considered. Numerical investigations are carried out for verification of the presented method, and the results show good accuracy and very high computational efficiency.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2007년도 정기 학술대회 논문집
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• pp.105-110
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• 2007

The differential equations governing free, in-plane vibrations of circular curved beams with elastic springs at beth ends, including the effects of axial deformation, rotatory inertia and shear defamation. are solved numerically using the corresponding boundary conditions. The lowest three natural frequencies are calculated over a wide range of non-dimensional system parameters, the radial, tangential and rotational spring parameters, the subtended angle, the slenderness ratio and the shear parameter.

• 소음진동
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• 제4권4호
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• pp.469-478
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• 1994

This paper desfcribes the formulation for the analysis of the free vibration of a circular cylindrical shell with elastic supports by the transfer influence coefficient method. This method was developed on the base of the concept of the successive transmission of dynamic influence coefficients. The analysis algorithm for circular cylindrical shell elastically restrained by springs, which plays an important role in many industrial fields, is discussed. The supporting springs have the axial, circumferential, radial and rotational spring constants uniformly distributed along the circumference of the shell. The simple computational results on a personal computer demonstrate the validity of the present method, that is, the numerical high accuracy, the high speed analysis method and the flexibility for programming, compared with results of the transfer matrixmethod and reference. We also confirmed that the present algorithm could obtain the solutions of high accuracy for system with a number of intermediate rigid supports. And we could easily treat the intermediate support and all boundary conditions by adequately varying the values of spring constants.

• 가정과삶의질연구
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• 제28권3호
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• pp.43-59
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• 2010

This study examined how much support families with pre-school children receive for child care along with the types of support they receive. The paper also investigated the factors that influence the financial and social support received from government, employers and grandparents of the children. Data for this study were obtained from a questionnaire completed by mothers of pre-school children (n=641) during the spring of 2009. The data were analyzed by the following methods: $\chi^2$, t-test, ANOVA, Logit analysis, and Tobit analysis using SPSS and STATA software. The profile of support for child care showed that approximately 33 percent of families with pre-school children received free or subsidized child care from the government, 12 percent received some forms of support for child care from the parents' employers, and 26 percent received support from grandparents either financially or in the form of free child care. The results of the Logit analysis demonstrated that families with pre-school children were more likely to receive child care subsides from the government when they had a higher number of pre-school children and a lower level of family income. The significant factors that influence support from employers were mother's educational level, the number of pre-school children, and family income. The significant factors that affect support from grandparents of the children were the mother's age, the mother's employment status, the type of residence, and the family type.

• 소음진동
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• 제5권4호
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• pp.515-524
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• 1995

Tubes in heat exchanger of fuel rods in reactor core are supported at intemediate point by support p0lates or springs. Current practice is, in case of heat exchanger, to allow clearance between tube and support plate for design and manufacturing consideration. And in case of fuel rod the clearance in support point can be generated due to the support spring force relaxation. Flow-induced vibration of a tube can cause it to impact or rub against support plate or against adjacent tubes and can result in fretting-wear. The tube-to- support dynamic interaction is used to relate experimental wear data from single-span test rigs to real multi-span heat exchanger configurations. The dynamic interaction cna be measured during experimental wear tests. However, the dynamic interaction is difficult to measure in real heat exchangers and, therefore, analytical techniques are required to estimate this interaction. This paper describels the nonlinear impact model of DAGS(Dynamic Analysis of Gapped Structure) code which simulates the tube response to external sinusodial or step excitation and predicts tube motion and tube-to-support dynamic interaction. Three experimental measurements-two single span rods excited by sinusodial force and a two span rod impacted by a steel ball are compared from the simulation nonlinear model of DAGS code. The simulation results from DAGS code are in good agreement with measurements. Therefore, the developed model of DAGS code is good analytical tool for estimating tube-to-support dynamic interaction in real heat exchangers.

• Asian-Australasian Journal of Animal Sciences
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• 제15권1호
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• pp.34-37
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• 2002

Two experiments were conducted to evaluate the nutritional value of common fodder tree leaves with goats fed at 50% of total ration. In experiment 1, leaves from six fodder tree species i.e., Ailanthus aitissima, Elaeagnus angustifolic, Morus alba (Mulberry), Populus spp, Robina pseudoacacia and Salix babylonia were harvested in spring and winter from northern areas of Pakistan. Chemical composition and apparent in situ dry matter digestibility (DMD) of fodder tree leaves were measured. Results showed that crude protein (CP) values were higher (p<0.05) in all the species during spring compared to winter (17.9% vs 12.0%). The concentration of NDF in Elaeagnus and Robinia was higher in spring, whereas no seasonal difference was found in other species. In situ DMD was higher (p<0.05) in Ailanthus and Populus at spring while it was higher (p<0.05) in Elaeagnus, Mulberry and Robinia at winter. There was no (p<0.05) seasonal effect on in situ DMD of Salix. In experiment II, four iso-nitrogenous and iso-caloric rations viz., A, B, C and D were prepared containing 50% (winter harvested) sun dried leaves of Salix, Robinia, Mulberry and Elaeagnus, respectively and 50% concentrate. Dry matter and crude protein intakes were higher (p<0.05) given ration A (Salix) whereas DM and CP digestibility was lowest (p<0.05) given ration B. Nitrogen retention was higher (p<0.05) given ration A. Goats fed on fodder tree leaves and concentrate showed moderate intake and digestibility.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2003년도 학술대회지
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• pp.313-323
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• 2003

The sliding wear behaviors of Zircaloy-4 nuclear fuel rod were investigated using two support springs with convex and concave shapes in room temperature air and water. The main focus is to compare the wear behavior of various test variables such as slip amplitude, environment, contact contours with different spring shape and a number of cycles. The results indicated that wear volume and maximum wear depth increased with slip amplitude in both air and water, but their trends tended to change according to the spring shapes and test environments. In air condition, the wear volume was controlled by wear debris behavior generated on worn surface. As a result, final wear volume and maximum wear depth decreased if a ratio of protruded wear volume to worn area $(D_p)$ would be saturated to specific value. This is because wear particle layer could accommodate large strain by accumulating and transforming wear particle layer. However, in water condition, metal-to metal contact was more dominant and wear volume was greatly affected by changed mechanical behavior between contact surfaces since wear debris should be generated after repeated plastic deformation and fracture. After wear test, worn surfaces were examined using optical microscope and SEM and details of wear mechanism were discussed using a ratio of wear volume to worn area $(D_e)$ at each test condition.