• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.9
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• pp.936-942
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• 2009

This paper presents the delivered power and reflection coefficient in metallic shielding enclosure with a sub-cavity, which are evaluated with the method of moments, sad describes a method for controlling the resonance characteristics of the metallic cavity by putting lossy dielectric material in the sub-cavity. In this paper we introduce carbon polystyrene-foam as lossy dielectric material and observe it's effects of reduction when the dimensions of the sub-cavity and permittivity of lossy dielectric material are changed. The results show that the reduction of the electromagnetic radiation can be achieved by controlling the amount of carbon in lossy dielectric material and the dimensions of the sub-cavity. The theoretical analysis is verified by the measured delivered power.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.11 no.6
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• pp.920-928
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• 2000

In this paper, using newly proposed size reduction technique, the aperture coupled microstrip patch antenna for a repeater system in a mobile communication cellular band (824~849 MHz) is developed with a wide bandwidth, small size, light weight, and low cost. The resonant frequency of microstrip antennas is related to the electric field distribution of the radiating patch. The field strength of $TM_{01}$ mode of a rectangular patch antenna is strongest at each of the extremities of the radiating patch, but negligible at center. Therefore, the size of a patch antenna can be effectively minimized by inserting the narrow rectangular dielectric into just under the edges of the resonant Patch. This Paper also proposes the bandwidth improvement technique by using under-coupling technique with a tuning stub. The VSWR is less than 1.5 : 1 for the whole cellular band. The simulation tool was HFSS, Agilent Technologies, Inc.

• Journal of the Earthquake Engineering Society of Korea
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• v.14 no.6
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• pp.55-65
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• 2010

The purpose of this experimental study is to evaluate the seismic performance of a 2 story RC shear wall system by the static reversal loading test. The lower 2 stories of the prototype structure were selected, and the specimens of this study were comprised of a T-type wall with an opening. The specimens were reduced to about 60% of the full scale size and were constructed to measure the result of the experimental variable regarding the existence of a lintel beam. To perform this study, the static repeated loading test was performed. According to the existence or absence of a lintel beam, the structural capacities and behavioral differences of the shear wall system were compared. The test results of this study showed that the specimen with a lintel beam underwent the seismic performance with an ultimate strength and ductility capacity better than the specimen without a lintel beam.

• Water for future
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• v.29 no.1
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• pp.213-220
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• 1996

This paper presents an experimental study on the discharge head of Cherepnov water lifter that was continuously operated with the aid of the siphon. The energy used by the Cherepnov water lifter is derived from the potential energy ofthe water itself. The lifter consists of three interconnected tanks and five pipes, one of which is open and two others are hermetically sealed. The effects of varying operating parameters such as the tank and pipe size, the ratio between head of discharge and drop height were analyzed. As a result, factors that can maximize the efficiency and increase the average delivery rate were indentified. When the ratio between head of discharge and drop height is about 0.5, the efficiency of Cherepnov water lifter is maximized. In order to design the efficient Cherepnov water lifter, the discharge head of the Cherepnov water lifter should be assigned to be twice as much as the drop height. The effect of tank size on the efficiency is less than 5%, while the effect of the pipe size is not negligible. The larger the pipe size is, the more the efficiency increases.

• Water for future
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• v.28 no.1
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• pp.145-152
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• 1995

This paper presents an experimental study on the Cherepnov water lifter that can pump or lift water without the use of external energy such as electricity. The energy used by the lifter is derived from the potential energy of the water itself. The liffter consists of three interconnected tanks, one of which is open and two others are hermetically sealed. The water level and the pressure in each tank were measured to improve the undestanding of the behavior and the operational charateristics of the lifter. The effects of varying operating parameters such as the inflow rate, tank and pipe sizes, the relative positions of the tanks were analyzed. As a results, factors that can maximize the efficiency, shorten the cycle time and increase the delivery rate were identified.

• Journal of Advanced Navigation Technology
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• v.4 no.2
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• pp.152-161
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• 2000

Recently, it is considered to combine the GPS receiver with the GLONASS for the improvement of performance and accuracy. This combined system reduces errors by SA for GPS, and has merits to select receivable satellite. In this paper, aperture-coupled patch antenna and small sized ceramic dielectric patch antenna are designed and implemented for GPS/GLONASS combined receiver, which show a wideband characteristics with circular polarization. The manufactured antennas have the bandwidth more than 240 MHz, VSWR less than 1.5:1, and the axial ratio less than 3dB, and satisfy required characteristics of the GPS/GLONASS antenna.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.10 no.1
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• pp.32-43
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• 1999

In this paper, the transformed QMSA to load a capacitor without limitation of the electric force on QMSA(Quarter-wavelength Microstrip Antenna) is designed. Bandwidth of the designed and manufactured antenna is 5.7% at the resonant frequency of 2.0 GHz and the resonant frequency and bandwidth versus change of any arbitrary feed point is observed. Since the size of wide slot width between the left and right parallel plate to load a capacitor is very wide bandwidth, will be suitable for very wide bandwidth communication. The radiation pattern characteristics of the designed antenna based on the dipole structure and the aperture structure analysis method. As calculation results, relative backward radation is - 5 dB.

• Fire Science and Engineering
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• v.22 no.4
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• pp.76-84
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• 2008

Researches on fire resistant performance of primary structural elements such as columns and beams located at above the ground have actively been doing than those located at the below the ground from many researchers. But the structural elements such as columns at underground is very important in aspects of not only structural performance but also fire environment. The columns at the basement carry all the structural loads from the above and that means very critical in fire circumstances than that located at above the grounds. To evaluate the fire resistance performance of primary structural elements located at below the ground we conducted several sorts of surveys that contained fire regulations from several countries and structural types, materials and status of passive fire protection methods.

• Journal of the Society of Naval Architects of Korea
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• v.30 no.4
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• pp.112-126
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• 1993

In this paper, unified requirements of IACS on longitudinal strength of ships are investigated using nonlinear wave loads analyses under short term irregular waves. Also, analyses on IACS wave data were carried out for the purpose of presenting the guideline for future use. While keeping theoretical consistensy, the rule requirements for horizontal shear force, bending moment and torsional moment are newly proposed for the ships of large deck openings bases on the calculation results for 17 sample ships. The requirements for side shell hydrodynamic pressure are also presented. All the calculated results are compared with other Societies and present KR rules. These formula will be checked when corresponding requirements of structural scantling are determined.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2012.10a
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• pp.1019-1022
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• 2012

Integral imaging is a promising technology for 3D imaging and display. Many parameters affect the performance of 3D integral imaging systems. Enhanced system performance is acquired by optimization of these system parameters with respect to defined performance metrics. In this paper, we present an approach to optimize the performance of 3D integral imaging system in terms of performance metrics under fixed resource constraints. In this analysis, system parameters such as lens numerical aperture, pitch between image sensors, the number of image sensors, the pixel size, and the number of pixels are determined to optimize performance metrics. Wave optics is utilized to describe the imaging process.