• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.21 no.5
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• pp.155-160
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• 2021

In this paper, we investigated the aptness of embroidered textile dipole antenna as a wearable antenna. We designed an 2.45GHz ISM band embroidered textile dipole antenna on polyester textile. We investigated its characteristics depends on 3 variables, thickness of textile(ttextile), distance between textile and surface of body(gbody) and conductance of surface of body(𝜎body). Thickness of textile(ttextile) was affecting on the antenna resonance frequency(fo). As the conductance of surface of body(𝜎body) was increased the antenna resonance frequency(fo) and the antenna gain were increased slightly. The increment of the distance between textile and surface of body(gbody) caused relatively large increment of the antenna resonance frequency(fo) and the antenna gain. From the results, in the case of designing an embroidered textile dipole antenna as a wearable antenna we should consider carefully the two variables, distance between textile and surface of body(gbody) and thickness of textile(ttextile). Due to its large variation, the distance between textile and surface of body(gbody) may be a technical barrier in designing embroidered textile dipole antenna.

• Journal of the Korean Institute of Telematics and Electronics
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• v.19 no.5
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• pp.20-25
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• 1982

A realization method of the microwave oscillator is proposed by the inherently stable transistor with a cavily resonator feedback loop. The real Part of the output impedance of the inherently stable bipolar transistor can be made to be negative at the resonance frequency by the high-Q cavity feedback loop, and the oscillation condition can be obtained with the matching section of the load. In this work the microwave transistor oscillator is realized with a silicon bipolar transistor HXTR 2101 and a reentrani cavity, and characteristic of the output power 10m Watts at 2.33 GHz osc. frequency can be verified experimentally.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.05a
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• pp.774-777
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• 2002

There are various methods to join mechanical structures together. They typically include welding, mechanical joints by bolts and other processes depending on specific needs. Analyses of joints in the mechanical structures are essential in understanding the dynamic characteristics of the structures. In this research an impulse technique is applies to investigate the dynamic behavior of joints produced by bolts. The length overlap in the joints was varied as the number of the bolts in the joins was changed. Also, the torque applied to the bolts were adjusted. Resonance frequencies were determined for the joints to evaluate the relationship between the increase in the applied torque and the increase in the number of bolts used in the joints. The results have demonstrated that the resonance frequencies of the joints increase with the increasing torque.

• Journal of the Korea Society of Computer and Information
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• v.9 no.4 s.32
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• pp.93-97
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• 2004

This paper proposed that a small type conductor surface open-loop antenna model for the moisture sensor and its operating characteristics were analysed numerically by using the moment methods. The numerical analysis results from this antenna model showed that this antenna could match the input impedance to $50[{\Omega}]$ by changing parameters of the antenna in the frequency range from 300[MHz] to 500[MHz]. This model also showed that the open-loop radius. height and wire width give a tremendous influence on the antenna resonance variation. while the loaded inductance values affects the variation or the input impedance at the resonance frequencies.

• The Journal of the Acoustical Society of Korea
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• v.14 no.4
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• pp.12-20
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• 1995

This paper describes principles and experimental results in conjunction with examining the possibility of the detection of effects from a cylindrical objects. Cylindrical objects have its own resonance frequency. The frequency varies according to the diameter, length etc. And acoustic sound, whose frequency and the harmonic components corresponding to resonance frequency, is radiated from the object. When an object have defect in itself, the radiated acoustic sound is different from normal one. So we can detect its defect by analysing frequency components of acoustic sound. We proved that detection of defective objects by acoustic signal analysis is possible automatically. Also the result can be applied to other kinds of objects.

• The Journal of the Acoustical Society of Korea
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• v.16 no.1
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• pp.16-23
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• 1997

As analysis of the forced dynamic response and vibrational mode for the cantilevered beam is described. Experimental results are compared with the natural frequencies and vibrational modes for the cantilevered beam using the theory of Bernoulli-Euler and finite element method. We have found 1st and 2nd resonance frequency of the cantilevered beam by means of the various external frequencies, $1{\sim}70Hz$, using magnetic transducer. And we have studied the vibrational displacement at obtained resonance frequency of the cantilevered beam. The experimental results for the nodes of cantilevered beam were 0 in 1st mode and 0,0.786 in 2nd mode. close agreement between the theoretically predicted results and experimental result was obtained for the vibrational mode.

• Journal of the Korean Wood Science and Technology
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• v.43 no.6
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• pp.777-783
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• 2015

Wood is an anisotropic material that shows the changes in hardness, quality and dimensions depending on the types of cells on three cross sections, size, array and so on. It can also be used in different ways according to its use, which requires a meticulous research, in order to maximize the utilization by understanding the nature and use; and by clarifying the theory and technologies. The research on relationship among wood's physical properties, density, and elasticity of modulus have been studied in Korea and abroad, but those studies were based on correlation gained through standardized specimen. Rather, the study on complete product is rare. Moreover, the previous reports are mostly concentrating on vibration mode and batting, though the wood's physical properties as a material have not been in the main focus. Therefore, this study will carried out for analyzing MOE through figuring material property out and comparing frequency adapting to the Canadian HardMaple bat. For comparison of material properties, we studied the annual ring and density of the bat; calculated the MOE with resonance frequency and formula (ASTM C1259); and verified the repulsive force of this material. As a result, the relevance of the resonance frequency and annual ring is weak, and in comparison in the grain direction in wood, the MOE value is higher when the grain direction in wood is excited horizontally than when is excited vertically, because the material is repulsive when grain direction is horizontal.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 1990.10a
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• pp.143-145
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• 1990

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.5 no.4
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• pp.206-210
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• 2012

In this paper wireless power transmission is discussed. The concept of non-radiative magnetic coupled resonance type wireless power transmission was introduced by MIT team at 2007, non-radiative type has been focused by many researchers. Authors present design of circuit parameters including driving frequency and verify the design by computer simulation.

• Journal of the Korean Society for Nondestructive Testing
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• v.20 no.3
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• pp.221-230
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• 2000

The usefulness and limitations of the impact-resonance method, which is a nondestructive evaluation (NDE) method for concrete, are studied by both experimental and theoretical methods. For the experimental study, several concrete slab specimens with various inclusions embedded were fabricated, and tested by the impact-resonance method. Some of the inclusions have been detected and accurately located, but some have not. The reasons for the failure in the latter cases have been investigated theoretically by using finite element analyses, from which the primary factors determining the success of the method have also been identified. This study will serve to enhance the understanding of the underlying physics and to improve the usefulness of the impact-resonance method as applied to concrete NDE.