• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 추계학술대회논문집
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• pp.713-716
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• 2004

In this paper a dynamic behavior of a double-cracked cnatilver beam with a tip mass and the moving mass is presented. Based on the Euler-Bernoulli beam theory, the equation of motion is derived by using Lagrange's equation. The influences of the moving mass, a tip mass and double cracks have been studied on the dynamic behavior of a cantilever beam system by numerical method. The cracks section are represented by the local flexibility matrix connecting two undamaged beam segments. ,Therefore, the cracks are modelled as a rotational spring. Totally, as a tip mass is increased, the natural frequency of cantilever beam is decreased. The position of the crack is located in front of the cantilever beam, the frequencies of a double-cracked cantilever beam presents minimum frequency.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1995년도 봄 학술발표회 논문집
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• pp.99-106
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• 1995

The seismic responses of a base Isolated Pressurized Water Reactor(PWR) are investigated using a mathematical model which expresses the superstructure as a linear lumped mass-spring and the seismic Isolator as an equivalent spring-damper. Time history analyses are performed for the 1940 El Centre earthquake with linear amplification. In the analysis 5% of structural damping is used for the superstructure. The effects of high damping rubber bearing on seismic response of the superstructure in base isolated system are evaluated for four stiffness model types. The acceleration responses in base isolated PWR superstructure with high damping rubber bearings are much smaller than those in fixed base structure. In the higher strain region where stiffness behaves non-linearly, the acceleration responses modelled by one equivalent stiffness are smaller than those in nonlinear spring model, and the higher stiffness spring model of isolator exhibits larger peak acceleration response at superstructure in the frequency range above 2.0 Hz. when subjected to linearly amplified 1940 El Centre earthquake.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2008년도 추계학술대회논문집
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• pp.515-520
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• 2008

This paper develops a mite element model of a polygon mirror scanner motor supported by the sintered bearing and flexible supporting structures to analyze the shock response by using the finite element method and the mode superposition method. The validity of the proposed model is verified by comparing the simulated natural frequencies and shock response with the experimental ones. It investigates the displacement and the stress of the most vulnerable component, i.e. a leaf spring due to shock, and it proposes a robust design of leaf spring of a polygon mirror scanner motor against shock.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 춘계학술대회 논문집
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• pp.361-365
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• 2002

This research is presented for optimizing the coefficients of spring and damper by impulse which is applied to AGV when the two containers are loaded on AGV. The suspension is estimated to the condition that two containers, initial velocity of container, initial height of container and maximum of suspension stroke. The coefficients of spring and damper are calculated numerically through Newmark method uses finite difference expansions. The procedure of calculation is applied by one DOFs of mass-spring-damper system. The coefficients of spring and damper have large value as increase of height or decrease of stroke. The result of calculation is shown in graph and the investigation is used AGV design.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 추계학술대회논문집A
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• pp.710-715
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• 2001

This research is presented for optimizing the coefficients of spring and damper by impact load which is applied to a trailer when the containers are loaded up trailer. The procedure utilize the condition that two containers, initial velocity of container, initial height of container and maximum of suspension stroke. The coefficients of spring and damper are calculated numerically through Newmark method uses finite difference expansions. The procedure of calculation is applied by one DOFs of mass-spring-damper system. The coefficients of spring and damper have large value as increase of height or decrease of stroke. The result of calculation is investigated and is used AGV design.

• Structural Engineering and Mechanics
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• 제52권5호
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• pp.1033-1049
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• 2014

The free vibration of functionally graded material (FGM) beams on an elastic foundation and spring supports is investigated. Young's modulus, mass density and width of the beam are assumed to vary in thickness and axial directions respectively following the exponential law. The spring supports are also taken into account at both ends of the beam. An analytical formulation is suggested to obtain eigen solutions of the FGM beams. Numerical analyses, based on finite element method by using a beam finite element developed in this study, are performed in order to show the legitimacy of the analytical solutions. Some results for the natural frequencies of the FGM beams are given considering the effect of various structural parameters. It is also shown that the spring supports show the greatest effect on the natural frequencies of FGM beams.

• 대한한방소아과학회지
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• 제25권3호
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• pp.77-84
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• 2011

Objectives: This study was performed to investigate the effect of hot spring therapy on children weight, body composition and heart rate variability. Methods: The study was carried out from 30 children who visited the spa from August 1, 2011 to August 31, 2011. We measured the change of weight, body composition, and heart rate variability after hot spring therapy for an hour per day. Results: The subject was consisted of 13 boys and 17 girls. This study revealed that their weight got lost from a hot spring therapy, which was statistically significant. Their body mass index(BMI) was decreased in from a hot spring therapy, which was not statistically significant. Total body water, muscle, protein, and mineral were decreased from a hot spring therapy, which was statistically significant. We measured HRV(heart rate variability) before and after the hot spring therapy. The mean HRT was increased, which was statistically insignificant. SDNN(standard deviation of the NN interval) and RMSSD(square root of the mean of the sum of the square of differences) were not different before and after the hot spring therapy. ln TP was decreased insignificantly. ln VLF was not affected before and after hot spring therapy. ln LF and ln HF was decreased, LF norm was increased, and HF norm was decreased, which were not statistically significant. Also, LF/HF ratio was increased insignificantly. Conclusions: From these results, we concluded that the weight, total body water, muscle, protein, and mineral got lost from the hot spring therapy. However, the HRV was not affected from the hot spring therapy.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2000년도 추계 학술발표회 논문집 Proceedings of EESK Conference-Fall 2000
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• pp.261-266
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• 2000

This paper consider the effects of the human-body stiffness on the response of the footbridge to ground shaking by an earthquake. A mass-spring, suggested by Tianjian Ji(1999), describing the stiffness of the human body and an inert mass specified in the Code as the appropriate human whole-body model are used and the responses of the structure in both cases to ground shaking are were compared. Finally this paper ascertains whether the consideration of the human body as a mass is safe in the aseismic design.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2011년도 춘계학술대회 논문집
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• pp.679-680
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• 2011

The Forced vibration characteristics of elastically restrained pipe conveying fluid with the attached mass are investigated in this paper. Based on the Euler-Bernoulli beam theory, the equation of motion is derived by using Hamilton's principle. The effect of attached mass and spring constant on forced vibration of pipe system is studied. Also, the critical flow velocities and stability maps of the valve-pipe system are obtained as each parameters.

• 전자공학회논문지
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• 제52권2호
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• pp.83-88
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• 2015

본 논문에서는 $2mm{\times}2mm$ 크기를 가지며 빔의 위치가 다른 2가지 종류의 압저항형 가속도 센서를 설계하고 제작하여 감도 특성과 온도에 따른 옵셋 특성을 측정하고 비교하였다. 4빔 스프링 구조와 8빔 스프링 구조를 가지는 압저항형 가속도센서를 제작 하였으며, ANSYS 프로그램을 이용하여 공진주파수 특성과 스트레스 분포도를 분석하고 제작하였다. 제작된 가속도센서의 감도와 온도에 따른 옵셋 특성을 측정하고 서로 비교하였다. 감도는 4빔 스프링 구조가 $21.38{\mu}V/V/g$으로 더 우수한 특성을 보였으며 온도에 따른 옵셋 출력 전압은 4빔 스프링 구조가 $154.45ppm/^{\circ}C$으로 더 작게 변화하였다.