• Journal of Satellite, Information and Communications
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• v.10 no.3
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• pp.109-113
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• 2015

This paper presents the study results on a dual band feed horn for the focused reflector. A coaxial waveguide structure is attractive to avoid blockage from the feeder. The inner conductor as a hollow waveguide is designed to excite TE11 of a circular waveguide for high frequency. For low frequency, the design of the outer coaxial waveguide that propagates coaxial TE11 and prevents fundamental TEM is presented. The horn size for generation of these modes results in the degradation of performance. The return loss is improved by a capacitive iris and an inductive iris The enhanced pattern symmetry by dual mode is presented. The horn design in this paper are verified through the test.

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.777-781
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• 2004

This paper presents a force/displacement sensing system to measure penetration depths and machining forces during pattering operation. This sensing system consists of a leaf spring mechanism and a capacitive sensor, which is mounted on a PZT driven in-feed motion stage with 1nm resolution. The sample is moved by a xy scanning motion stage with 5nm resolution. The constructed system was applied to nano indentation experiments, and the load-displacement curves of silicon(111) and aluminum were obtained. Then, the indentation samples were measured by AFM. Experimental results demonstrated that the developed system has the ability of preforming force/depth sensing indentations

• Journal of the Korean Society for Precision Engineering
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• v.22 no.12 s.177
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• pp.42-50
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• 2005

This paper presents an ultra precision machining system using a high sensitive force sensing module to measure machining forces and penetration displacement in a tip-based nanopatterning. The force sensing module utilizes a leaf spring mechanism and a capacitive displacement sensor and it has been designed to provide a measuring range from 80 ${\mu}N$ to 8 N. This force sensing module is mounted on a PZT driven in-feed motion stage with 1 nm resolution. The sample can be moved by X-Y scanning motion stage with 5 nm resolution. In nano indentation experiments and patterning experiments, the machining forces were controlled and monitored by the force sensing module. Then, the patterned samples were measured by AFM. Experimental results demonstrated that the developed system can be used as an effective device in nano indentation and nanopatterning operation.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.1109-1112
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• 2004

This paper presents a high sensitive force sensing module to measure machining forces for a tip-based nanopatterning instrument. The force sensing module utilizing a leaf spring mechanism and a capacitive displacement sensor has been designed to provide a measuring range from 80$\mu$N to 8N. This force sensing module is mounted on a PZT driven in-feed motion stage with 1 nm resolution. The sample can be moved by a X-Y scanning motion stage with 5 nm resolution. In the patterning experiments, the machining forces were controlled and monitored by the force sensing module. Then, the patterned sample was measured by AFM. Experimental results demonstrated that the developed force sensing module can be used as an effective sensing device in the nanopatterning operation.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.12
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• pp.2268-2272
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• 2010

This letter presents that a rectenna can utilize more stable wireless power by using a new design dual band/dual polarization microstrip patch antenna and 2 stage voltage multiplier at 2.4 GHz band and 3.1 GHz band. The proposed antenna is a new microstrip patch antenna design to make impedance matching possible by using slotted capacitive coupling between the patch and $50\Omega$ feed line on a ground plane. Its advantage is that the size of the rectenna can be reduced by using $50\Omega$ feed line on the ground plane, which can be used efficiently. The dual band/dual polarization microstrip patch antenna shows circular polarization at 2.4 GHz band and linear polarization at 3.1 GHz band. Under -10 dB return loss, The dual band/dual polarization microstrip patch antenna obtains 340 MHz bandwidth as 2.23~2.57 GHz and 375 MHz bandwidth as 2.95~3.325 GHz. Also, 2 Stage Voltage multiplier is possible to operate at 2.4 GHz band and 3.1 GHz band. The designed retenna can usually obtain wireless power at both 3.1 GHz band, and 2.4 GHz band applications such as Wi-Fi, Bluetooth, Wireless LAN, etc. So more stable wireless power can be utilized at the same time.

• Journal of Advanced Navigation Technology
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• v.16 no.1
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• pp.27-34
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• 2012

In this paper, Coplanar waveguide(CPW)-fed slot loop antenna, which is applicable to the dual band(2.4GHz~2.4835GHz, 5.15GHz~5.825GHz) for the wireless LAN, is proposed. In order to miniaturize the proposed antenna, slot loop is bent by meandering. The resonant frequencies in the required dual band are adjusted by variation of the resonant length of slot loop as well as slot width. In particular, use of capacitive coupling CPW feed provides impedance matching without a seperate matching circuit, because the amount of electromagnetic coupling can be controlled by the offset between feed and radiator. As a result, it has been observed that the proposed antenna satisfies not only the required return loss(${\leq}10dB$) but also has high efficiency(${\geq}80%$) over the whole frequency band. In order to check the validity of the proposed antenna, some simulated results for return loss and radiation pattern are presented in comparison with the measured results.

• Journal of the Korea Institute of Military Science and Technology
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• v.4 no.1
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• pp.124-136
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• 2001

In this paper, we designed and manufactured the Ku-band circular waveguide antenna to do wireless communication with a ground radar as on-board antenna of missile. Using the MATLAB and the HFSS, we designed the circular polarizer which has a characteristic of circular polarization and broadband using the capacitive pin method, the feeder to feed coaxial line to circular waveguide, and a stopper to prevent a conductor material from being inserted. Then we simulated the designed antenna using the HFSS, obtained the gain and the radiation pattern. Because of a difficulty of manufacture, we established a manufacture process procedure. Antenna is manufactured with this procedure, test results of the manufactured antenna are the axial ratio of 1.37 ~ 1.72, the 3 ㏈ beamwidth of $72.23^{\circ}{\sim}78.54^{\circ},$ and the gain of 3.26 ~ 4.61 ㏈ within frequency band. We knew that these results are similar with simulation results. Also, we confirmed that the manufactured antenna is satisfied with requirement conditions through performance test, environmental test and flight test.

• Membrane Journal
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• v.29 no.5
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• pp.276-283
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• 2019

In this study, The experiments of the confirmation of the fouling phenomena in CDI process and the establishment of its removal process conditions were carried out. The foulant concentrations of humic acid sodium salt (HA) added to the feed solution were 5, 10, 15 mg/L, respectively. The occurrence of fouling under the certain adsorption/desorption conditions could be confirmed with an increase in adsorption and desorption concentration curve over time. Both the voltage and time in adsorption and desorption processes were changed to eliminate the fouled pollutants. Typically, the fouling removal condition was found at the adsorption condition 1.2 V/5 min and the desorption condition -3 V/2 min, respectively.

• Journal of the Korean Institute of Telematics and Electronics T
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• v.35T no.1
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• pp.48-58
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• 1998

For the purpose of designing novel capacitance pressure sensor, several effects on sensitivity such as parasitic capacitance effects, temperature/thermal drift and leakage current have to be eleiminated. This paper proposed the experimental studies on frequency compensation method by electronic circuit technique, C-V converting method with switched capacitor and C-F converting method with schmitt trigger circuit. The third interface circuit by frequency compensation method is composed to eliminate the drift and leakage component by comparision sensing frequency with reference frequency. The signal transmission is realized by digital signal to minimize the influence of noise and high resolution is obtained by means of increasing the number of digital bits. In the fabricated high performance C-V interface, the offset voltage was not appeared, and in case of voltage source, 4.0V, feed back capacitance, 10㎊, the pressure, 0~10 ㎪, the sensitivity of C-V converter is 28 ㎷/㎪.V, the temperature drift characteristic, 0.051 %F.S./$^{\circ}C$ and C-F converter shows -6.6 Hz/pa, 0.078 %F.S./$^{\circ}C$ respectively, relatively good ones.