• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.4 s.175
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• pp.1032-1038
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• 2000

The stress field in the body by tangential loading of a rectangular patch on a semi-infinite solid has been solved analytically using potential function. The validity of result of this study was proved by Saint-Venant's principle in the remote region and in the vicinity of the surface with superposition of point loads.

• Proceedings of the Korea Concrete Institute Conference
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• 1995.04a
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• pp.257-262
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• 1995

In this study, after concrete cylinders were made on the condition of varying water-to -cement ratio, and cured 80 days compressive strength and splitting tensile strength were performed and moduls of elasticy is obtained. The fracture energy was obtained by acting three point bending on the 80cm in length. This test involved static loading test and dynamic loading test. In this work, the new interrelation of the material constants was obtained clearly and the property of the mixture was inspected, including the relation between the fracture energy and all kind of the material constants.

• Journal of the Korean Society for Precision Engineering
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• v.20 no.11
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• pp.158-165
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• 2003

A specific experimental method, the Split Hopkinson pressure bar (SHPB) technique has been widely used to determine the dynamic material properties under the impact compressive loading conditions with strain rate of the order of 10$^3$/s∼l0$^4$/s. In this paper, dynamic deformation behaviors of rubber materials widely used for the isolation of vibration from structure under varying dynamic loading are determined by using plastic SHPB technique. A transition point to scope with the dynamic deformation behavior of rubber-like material is defined in this paper and used to characterize the specifics of the dynamic deformation of rubber materials.

• Journal of the Korean Wood Science and Technology
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• v.46 no.4
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• pp.301-308
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• 2018

This study aimed to obtain basic climate information for effective moisture control in wood in Korea. Two independent climate indexes, namely drying index (DI) and wetting index (WI), were determined using hourly weather data for 82 locations recorded from 2009 to 2017. These data were collected from the Korea Meteorological Administration (KMA). Hourly data had not been measured prior to 2009. DI and WI revealed that all regions were cold and wet except Baengnyeongdo, which was classified as a cold and dry region. DI and WI were normalized assuming that wetting and drying were equally important phenomena. Then, the normalized indexes were combined into moisture index (MI) to rank the moisture loading of the regions. The MIs showed that Seogwipo had the greatest moisture loading in Korea, followed by Seongsan, Namhae, and Geoje. The MIs suggested that Korea exhibited severe moisture loading. Further studies are required to investigate the relation between MI and moisture content on wood surfaces from a wood maintenance point of view.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05a
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• pp.82-85
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• 2006

In this study, the fatigue tests were performed on a series of reinforce concrete beams with type of aggregate to investigate the fatigue behavior. The four point loading system is used in the fatigue tests. In these tests, relations between the repeated loading cycles and mid-span deflections, number of repeated loading cycles when specimen was fractured were observed. On this basis, the mid-span deflections, the crack growth and failure mode of beams were studied. The result of tests, reinforce concrete beams with recycled aggregate were about similar failure mode with natural aggregate concrete beam.

• Journal of electromagnetic engineering and science
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• v.2 no.1
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• pp.45-49
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• 2002

This paper presents the basic characteristics of a forced resonant type EMI dipole antennas for frequencies below 80 MHz in which two reactance elements are used for the impedance matching at the fined point. The input impedance of the short dipole less than half-wavelength is controlled by the properly determined loading position and the value of loading reactance. The numerical results show that the small-sized EMI dipole antenna with loller antenna factors for frequencies below 80 MHz can be realized by the reactance loading. In case tole proposed center driven forced resonant type EMI dipole antenna with 0.3 λ length is loaded from the center, the input impedance is matched at feed line with 50 $\Omega$, and hence the antenna has lower factors in the frequency range of 30 to 80 MHz.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.2
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• pp.502-511
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• 1994

A video deck mechanism is composed of various cams, links, and gears, and it requires precise movement. So kinematic motion between parts should be considered to get desired movement depending on the timing chart which defines movement of each part to get desired mode. Also dynamic effects should be considered to get right tape tension and to estimate motor force required to obtain accurate motion. The design process of the deck mechanism of VCR is explained briefly. The loading block of the deck mechanism is divided into a tape translational group and a brake control group. Each group is modeled for kinematic and dynamic analysis. Finally, two groups are combined together to analyze the loading block of the deck mechanism. Results are used to understand and modify an existing design.

• Proceedings of the Korea Concrete Institute Conference
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• 1990.10a
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• pp.169-174
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• 1990

Fracture tests were carried out in order to investigate the flexural behavior of SFRC (Steel Fiber Reinforced Concrete) structures. Sixty three SFRC beams were used in the tests, the fracture mode, the relationships between loading and strains, and the relationships between loading and mid-span deflections of the beams were observed under the three point bending loading. From the test results, the effects of steel fiber contents and a/h ratio on the concrete flexural behavior were studied, and the stress intensity factors and the flexural strength of SFRC beams were calculated. According to the results of regression analysis, predicting formulas for the flexural strength of SFRC beams are also suggested.

• The KSFM Journal of Fluid Machinery
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• v.13 no.4
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• pp.51-57
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• 2010

This paper describes the structural design and testing for 1.5kW class wind turbine composite blade. In order to calculate the equivalent material properties rule-of-mixture is applied. Lay-up sequence, ply thickness and ply angle are designed to satisfy the requirements for structural integrity. Structural analysis by using commercial software ABAQUS is performed to assess the static, buckling and vibration response. And to verify the structural analysis and design, the full scale structural test in flapwise direction was performed under single point loading according to loading conditions calculated by the aerodynamic analysis and Case H (Parked wind loading) in IEC 61400-2.

• Journal of the Korean Ceramic Society
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• v.35 no.8
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• pp.850-856
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• 1998

The dynaamic fatigue behavior of alumina ceramics was observed at room temperature using four-point bending method. Dynamic fatigue fracture strength was observed as function of down speed and notch length. The crack growth exponent of the specimens was calculated from the fracture strength and lifetime in dynamic fatigue test. After loading the stresses in the range of 0% to 105% compared with the average in-ert strength the value of residual fracture strength was measured for unnotched and 0.5mm notched speci-mens at the 0.001 and 0.0005 mm/min down speed respectively. After the 95% stress of the average inert strength was applied repeatedly the value of rsidual fracture strength was measured for 0.5mm notched specimens at the 0.001 and 0.0005 mm/min down speed respectively. The material constant A was found to be almost the same and not to depend on the loading mode or the down speed for unnotched and notched specimen. The value of fracture strength with time calculated from the constants n and A was in good agreement with the measured value.