• Advances in concrete construction
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• 제8권1호
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• pp.9-19
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• 2019

This paper describes an experimental investigation on hybrid fiber reinforced concrete (HYFRC) beams. And the main aim of this present paper is to examine the dynamic characteristics and damage evaluation of undamaged and damaged HYFRC beams under free-free constraints. In this experimental work, totally four RC beams were cast and analyzed in order to evaluate the dynamic behavior as well as static load behavior of HYFRCs. Hybrid fiber reinforced concrete beams have been cast by incorporating two different fibers such as steel and polypropylene (PP). Damage of HYFRC beams was obtained by cracking of concrete for one of the beams in each set under four-point bending tests with different percentage variation of damage levels as 50%, 70% and 90% of maximum ultimate load. And the main dynamic characteristics such as damping, fundamental natural frequencies, mode shapes and frequency response function at each and every damage level has been assessed by means of non-destructive technique (NDT) with hammer excitation. The fundamental natural frequency and damping values obtained through dynamic tests for HYFRC beams were compared with control (reference) RC beam at each level of damage which has been acquired through static tests. The static experimental test results emphasize that the HYFRC beam has attained higher ultimate load as compared with control reinforced concrete beam.

• Journal of the Korean Wood Science and Technology
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• 제42권2호
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• pp.130-137
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• 2014

Nondestructive evaluation (NDE) method by using a resonance frequency mode was carried out for ceramics made from particle boards with different phenol resin impregnation ratios (30, 40, 50, 60%) at carbonizing temperature of $800^{\circ}C$. The material for ceramics was Miscanthus sinensis var. purpurascens board. Dynamic modulus of elasticity increased with increasing impregnation ratio. There was a close relationship of dynamic modulus of elasticity and static bending modulus of elasticity to modulus of rupture (MOR). However, the result indicated that correlation coefficient is higher in dynamic modulus of elasticity to MOR than that in static modulus of elasticity to MOR. Therefore, the dynamic modulus of elasticity using resonance frequency by free vibration mode is more useful as a nondestructive evaluation method for predicting the MOR of ceramics made from Miscanthus sinensis var. purpurascens particle boards by different phenol resin impregnation ratios.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2003년도 추계학술대회 논문집(I)
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• pp.187-191
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• 2003

Aluminum carbody for rolling stocks is light and perfectly recycled, but includes severe defects which are very dangerous to fatigue strength. Static load test has been performed up to date to assess structural safety of the carbody. However, static load test is not sufficient to evaluate fatigue strength of the carbody, because fatigue failure is caused by dynamic load. In this study, the established load test methods for carbody are described and the characteristics of the methods are discussed. Also, a testing method to simulate dynamic loading condition is proposed for evaluation of fatigue strength of the carbody The results by the proposed testing method are compared with the results by the static load test and new findings are discussed.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2000년도 가을 학술발표회논문집(I)
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• pp.75-80
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• 2000

Evaluation method of seismic performance has mainly used elastic spectrum analysis. This method has simplicity of analysis but deficiency of accuracy. And evaluation method of seismic performance using inelastic dynamic analysis reflects accurately inelasticity of material but hardly reflects site effects. This study suggested evaluation scheme of seismic performance for bridge structure using capacity spectrum method applied inelastic static analysis and standard design response spectrum of Korea Standard Specification for Highway Bridge. Two results, capacity spectrum method and inelastic dynamic analysis method, are very similar. As a result, this study appropriately supply both simplicity of analysis and accuracy of result.

• 한국군사과학기술학회지
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• 제5권2호
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• pp.149-158
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• 2002

Static Characteristics of the system, such as weight, center of gravity etc., are inspected and regulated through the whole design process of a light weight torpedo system, and the nominal condition of the characteristics is prescribed for standardization of manufacturing and fabrication. It is possible that a real system or assembled system has different static characteristics from that of the nominal condition. It is required to evaluate the tolerance of the static characteristics within which the performance of the system should not be contaminated by the static characteristics. In this paper, an evaluation method of the tolerance is described for light weight torpedo systems. The method is to check on the performance and related critical parameters of light weight torpedoes. The checking items are composed of general conditions of underwater mobile systems such as stability and dynamic sensitivity and specified performance requirements for light weight torpedoes.

• Journal of the Korean Wood Science and Technology
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• 제32권3호
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• pp.8-14
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• 2004

Nondestructive evaluation (NDE) technique method using a resonance frequency mode was carried out for woodceramics produced at different carbonizing temperatures (600℃, 800℃, 1000℃, 1200℃, 1500℃) at the phenol resin impregnation rate of 70%, for three kinds of species (Pinus densifora, Pinus koraiensis, Larix leptolepis), respectively. There was a poor relationship between density and static bending MOR. However, close correlations were found between dynamic MOE_d and static bending MOR, and between static MOEs and MOR. Especially, the correlation coefficient was highest between MOE_d and static bending MOR. Therefore, the MOE_d using the resonance frequency mode is useful as a NDE method for predicting the MOR of woodceramics produced at different carbonizing temperatures.

• Steel and Composite Structures
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• 제2권2호
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• pp.113-128
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• 2002

The performance of steel MRF with rigid connections, proportioned by adopting different capacity design criteria, is evaluated in order to highlight the effectiveness of static non-linear procedure in predicting the structural seismic behavior. In the framework of the performance-based design, some considerations are made on the basis of the results obtained by both dynamic time histories and push-over analyses, particularly with reference to the damage level and the structure ability to withstand a strong earthquake.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.102-106
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• 2003

An experimental modal analysis and dynamic stiffness evaluation of a moving body structure of a high speed machining center are presented in this paper. The natural frequencies and corresponding modes, and dynamic compliance of a moving body structure of high speed machining center are investigated by using F.E.M., hydraulic exciter test, and impulse hammer test. The lowest three natural frequencies were found to be 56.6 Hz, 112.7 Hz, and 142.7 Hz by FEA respectively, while those were 55 Hz, 112 Hz, 131 Hz by experimental analysis. Furthermore, both computed and measured absolute dynamic compliances of the moving body structure in iso-direction showed good agreement especially at the first two mode frequencies. With our experimental data, the dynamic characteristics of the machining center can be exploited to get a new development of structural dynamic design and modification.

• 한국의학물리학회지:의학물리
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• 제17권2호
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• pp.114-122
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• 2006

세기조절방사선치료에는 다엽콜리메타의 구동방식에 따라 static 방법과 dynamic 방법이 있다. 세기조절방사선치료의 정도관리는 치료계획의 정도관리, 치료정보의 전달에 관한 정도관리, 치료전달 과정에 대한 정도관리를 통하여 이루어진다. 여기서는 static 방법과 dynamic 방법에 대하여 같은 조건으로 치료계획 정도관리를 시행하여 dynamic 방법의 환자 적용에 대한 타당성을 살펴보았다. 세기조절방사선치료에서 다엽콜리메타의 움직임이 static 방법인 stop and shoot 방법과 다엽콜리메타의 움직임이 dynamic 방법인 sliding window 방법과 비교검토한 결과 임상표적용적(clinical target volume, CTV)의 크기가 직경 3 cm인 경우에서는 중심점에서의 선량분포 차이가 0.2%였으며, 선량분포의 90% 면적의 차이가 2.7%였으며, CTV의 크기가 직경 7 cm인 경우에서는 중심점에서의 선량분포 차이가 0.2%였으며, 선량분포의 90% 면적의 차이가 2.2%였으며, CTV의 크기가 12 cm인 경우에서는 중심점에서의 선량분포 차이가 0.4%였으며, 선량분포의 90% 면적의 차이가 2.9%였다. 실제 폐암 환자에서도 CTV의 크기에 따라 static 방법과 dynanic 방법에서 중심점에서의 선량 차이는 0.3%에서 0.6%를 나타내고 있다. 가상 펜텀에서는 CTV의 크기에 따라 중심점에서의 측정 선량이나 90% 등선량 곡선 면적이 차이가 없었고, 실제 폐암환자에서는 중심점의 측정선량은 차이가 없었지만 90%등선량곡선의 면적은 CTV 가 커짐에 따라 두 방법간에 차이가 커짐을 알 수 있었다.

• 한국방재학회 논문집
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• 제11권1호
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• pp.45-49
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• 2011

본 연구에서는 소방방화복의 무게가 최대 신체활동 후 신체의 평형성과 민첩성에 미치는 영향을 조사하여 소방공무원의 안전을 위한 기초자료 제공을 목적으로 한다. 신체의 정적평형성 평가를 위하여 눈감고 한발로 서기와 동적평형성 평가로는 평균대 걷기를 실시하였으며, 신체의 정적민첩성 평가는 전신반응검사 동적민첩성 평가는 반복 옆뛰기를 실시하였다. 연구결과 최대 지친 상태에서 소방방화복의 무게는 신체의 정적평형성과 동적민첩성에 영향을 미치는 것으로 나타났으며 향후 소방공무원의 안전을 위한 실제적인 연구에 유용할 것으로 판단된다.