• ETRI Journal
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• v.36 no.6
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• pp.1062-1065
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• 2014

A novel substrate-integrated waveguide (SIW) cavity-backed slot antenna is proposed in this study to achieve enhanced-gain performance. The peak gain is remarkably improved with the use of an SIW cavity and metallic superstrate. The superstrate comprises a single rectangular slot window and two half-wavelength patches. The gain can be enhanced by combining the in-phase radiating fields. Further, the 10 dB bandwidth of the proposed antenna ranges from 2.32 GHz to 2.49 GHz, which covers the wireless local area network band. The measured peak gain is 9.44 dBi at 2.42 GHz.

• Journal of Electrical Engineering and Technology
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• v.10 no.1
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• pp.314-319
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• 2015

The conventional geometry of a plate microstrip resonator is made up of a single metallic patch, which is printed on a monolayer dielectric substrate. Its arrangement is simple and easy to make, but it is limited in its functional abilities. Many searches have been realized to improve the bandwidth and the gain of the microstrip resonators. Among the various configurations proposed in the open literature, the stacked geometry seems to be very promising. By appropriate design, it is able to provide the operation in dual frequency mode, wide bandwidth enough and high gain. The theoretical investigations of structures composed of two stacked anti-reflection coatings, enhanced metallic coatings are available in the literature, however, for the stacked configurations involving three metallic coatings or more, not to exact or approximate analysis was conducted due to the complexity of the structure.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2009.05a
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• pp.64-67
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• 2009

Vibrational micro-forming of pyramidal shape patterns was conducted for an Al superplastic alloy, Al 5083 and a Zr-based bulk metallic glass, $Zr_{62}Cu_{17}Ni_{13}Al_8$. A vibrational micro-forming system was specially designed for generating vibrational load by combining a PZT actuator with a signal generator. Single crystal Si micro dies with wet-etched pyramidal patterns were used as master dies for vibrational micro-forming. The micro-formed pattern height was increasing with increasing the frequency of the vibrational load. In particular, the vibrationally-microformed pattern height was similar or even higher than the statically-microformed pattern height when the load frequency exceeded about 125 kHz. It was also observed that the crystal grains affect the surface quality of the microformed pattern and the distribution of the pattern height in the die cavity array.

• Journal of Sensor Science and Technology
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• v.32 no.4
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• pp.252-256
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• 2023

A one-step method for nanoscale patterning of silver ionic ink on a substrate is developed using a microscale, elastic mold deformation. This method yields unique micro/nanoscale metallic structures that differ from those produced using the original molds. The linewidth of these metallic structures is significantly reduced (approximately 10 times) through the sidewall deformation of the original mold cavity on a thin liquid film, as verified by finite element analysis. The process facilitates the fabrication of various, isolated and complex micro/nanoscale metallic structures with negligible residual layers at low cost and high throughput. These structures can be utilized for various applications, including optoelectronics, wearable sensors, and metaverse-related devices. Our approach offers a promising tool for manipulation and fabrication of micro/nanoscale structures of various functional materials.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.10
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• pp.1115-1121
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• 2008

In this paper, dielectric slab loaded cylindrical cavity resonator measurement technique is presented to determine the dielectric constant of a dielectric material. The dielectric constant is measured by the resonant frequency deviation of empty and dielectric slab loaded cavity. Characteristic equations are derived by th exact field analysis. The measurement configurations are formed using HP8719A vector network analyzer and an experimental cylindrical metallic cavity with circular cross-section. The validity of the theory is confirmed by experiments and CST MWS 4.0(3D simulator). The results were in the whole satisfactory. The measured dielectric constant of teflon and bakelite are 2.03 and 4.44, respectively.

• Journal of the Korean Society for Precision Engineering
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• v.23 no.4 s.181
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• pp.60-66
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• 2006

For the purpose of finding out the sound field characteristics in a rectangular cavity, analytical and experimental studies are performed with white noise input. Two-microphone impedance tube method is used to measure the impedances of foamed aluminum. Foamed aluminum is well known metallic porous material which has excellent properties of light weight and high absorbing performance. And predicted impedances of foamed aluminum are compared with measured impedances. The predicted acoustical parameters are applied to the theoretical analysis to predict sound pressure field in the cavity. The measured sound absorption effects are compared with the predicted values for both cases with and without foamed aluminum lining in the cavity of the rectangular enclosure.

• Journal of Electrical Engineering and Technology
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• v.7 no.3
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• pp.406-410
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• 2012

This paper looks into the field inside the wide rectangular box structure that is excited by the High Power Electromagnetic(HPEM) source as a potential threat to electric grid and communication networks causing malfunction or destruction. The rectangular box is assumed power/ground planes and its internal field is calculated by the cavity model with the lightning strike excitation as an HPEM pulse. The accuracy of the calculation method employed here is validated through a $156mm{\times}106mm{\times}508{\mu}m$ parallel metallic plate case which is manufactured and tested, and is applied to the size of a building. With the help of the cavity model that takes into account loading, the level of the electric field is shown to decrease when a metal pillar is loaded between the power and ground planes.

• Journal of Chest Surgery
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• v.39 no.3 s.260
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• pp.251-254
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• 2006

Metallic fixations devices are widely used in the surgical management of fractures and dislocations of shoulder. It is known that Kirschner wire (K-wire) may migrate into the thoracic cavity or other organs may occur. We report a case in which a K-wire previously placed in the clavicle migrated into the thoracic cavity without causing any trauma to the major vascular structures and was removed successfully by thoracoscopic surgery.

• Korean Journal of Veterinary Service
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• v.44 no.1
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• pp.45-49
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• 2021

A 23-month-old Holstein cattle showed excess salivation and reluctance of walking and suddenly died after forced sudden movements. Grossly, numerous fibrous adhesions were present within cranial abdominal cavity including the reticulum and diaphragm and thoracic cavity involving lungs, pericardial sac, and heart. A perforation made by a 10 cm-long sharp-ended wire was detected in the reticulum. Histopathologically, fibrous suppurative epicarditis and myocardial necrosis were observed. Fibrosis with neovascularization were found in lungs, spleen, and liver. And granulomatous reticulitis was observed. For differential diagnosis, no pathogenic bacteria were detected through microbiological tests and PCR results were also negative for bovine susceptible pathogenic antigens. Based on the gross and histopathological examination, we diagnosed this case as chronic traumatic pericarditis. Cattle are inquisitive and prone to swallow various kinds of metallic foreign bodies since they do not use their lips. Therefore, avoiding ingestion of metallic objects in animal feed and animal areas by careful environmental management of farms is required and farmers should give the adequate minerals and vitamins into the feeds not to lick or shallow foreign bodies in case of mineral deficiency. For veterinary practitioners, physical examination, blood tests, and diagnostic imaging (X-ray and Ultrasonography) are required for an exact diagnosis. Furthermore, placing the magnets in rumen would be effective for prophylactic administrations.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.12
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• pp.1402-1409
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• 2008

In this paper, a low temperature co-fired ceramic cavity backed antenna in order to improve the performances of radiation and bandwidth for the antenna with high relative dielectric constant is proposed. Low temperature co-fired ceramic cavity consisted of several ground planes with closely spaced metallic vias connected. It is shown that the size of a low temperature co-fired ceramic cavity has the effects on the performances of radiation and bandwidth for the antenna. The proposed 2x4 low temperature co-fired ceramic cavity backed antenna is $10{\times}20\;mm^2$ in size. Measured results show antenna gain of $11.8{\sim}14.1\;dBi$ and bandwidth of 13 %(7.9 GHz) in the $57{\sim}64\;GHz$ band.