• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.5
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• pp.468-474
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• 2010

In this paper, a VCHO(Voltage Controlled Harmonic Oscillator) for K-band application has been designed and implemented. The proposed oscillator has a structure of two hair-pin resonators placed on input and output of active device. Using in/out common frequency tuning structure, the VCHO yields some advantages of the enhanced fundamental frequency suppression characteristic as well as the improved output power of second harmonic. According to implementation and measurement results, it was shown that a VCHO provides an output power of -2.41 dBm, a fundamental frequency suppression of -21.84 dBc, and phase noise of -101.44 dBc/Hz at 100 kHz offset. In addition, as for the bias voltage from 0 V to -10 V for the varactor diode, output frequency range of 10.58 MHz is obtained with a power variation of ${\pm}0.19\;dB$ over its frequency range.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.5
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• pp.552-559
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• 2011

In this paper, the frequency reconfigurable antenna is proposed and designed. The proposed antenna is designed using the vertically stacked dipole structures and have the operating band for Cellular, PCS/WCDMA/Wibro/WiFi and WiMAX. The operating frequency band is selected by three pair of PIN diodes using the voltage difference between each dipole antenna and feeding transmission lines. The proposed antenna meets the required operating bandwidth and the maximum gain for each frequency band are measured as 6.3 dBi, 5.4 dBi and 5.8 dBi, respectively. The proposed antenna in this paper can be applied for the future mobile small base station or repeater antenna because this antenna can provide the small size and high gain features.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.2
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• pp.123-129
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• 2002

5-bit broadband MMIC phase shifter has been designed and fabricated. For the broadband performance, 11.25$^{\circ}$, 22.5$^{\circ}$, 45$^{\circ}$ and 90$^{\circ}$ bit have been designed with Lange coupler and 180$^{\circ}$ bit has been implemented by using shorted coupled line with Lange coupler and $\pi$-network of transmission line. Due to Lange coupler with large size, the Lange couplers have been folded far circuit size reduction. Low loss PIN diode has been utilized as a switch for each bit. Fabricated 5-bit broadband phase shifter shows the measured results that RMS phase error of 5 major phases is 3.5$^{\circ}$, maximum insertion loss is 12.5 dB, and maximum input and output return loss are 7 dB and 10 dB, respectively. The size of fabricated phase shifter is 6.5$\times$5.3 $ extrm{mm}^2$.

• Proceedings of the KIEE Conference
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• 2004.11c
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• pp.571-573
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• 2004

본 논문에서는 휴대용 선량계 시스템에 거리 무선 통신 방식중 Bluetooth를 이용하여 선량계를 구현한 것에 대해 논하였다. 휴대용 선량계란 감마선과 속중성자 및 열중성자를 현장에서 실시간으로 측정 할 수 있는 기기이다. 휴대용 선량계는 선랑계의 소형화를 위해 모듈별로 구성하여 공간의 최적화를 취하였다. 모듈의 구성은 시스템의 전반적인 제어를 하는 CPU부 센서로부터 측정한 데이터를 처리하는 신호처리부 방사선량을 측정하는 센서부로 구성되어졌다. 센서 모들의 PIN 다이오드와 MODFET 센서를 이용하여 감마선, 속중성자, 열중성자를 측정한다. 휴대용 선량계를 관리하고 측정한 데이터의 백업 및 분석을 위하여 PC용 관리프로그램과 근거리 무선 통신(Bluetooth)을 사용하여 통신하도록 만들어 사용하였다. 측정 지역의 방사선량을 휴대용 선량계로 측정하여 PC용 관리프로그램에서 실시간으로 방사선량을 확인 할 수 있다.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.12
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• pp.1097-1102
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• 2003

In this paper, we used only PR as etching mask, while it used usually Cr/AU as etching mask, and in order to fabricate a photosensor has the increased sensitivity, we investigated on the sensitivity of general type and p-i-n type diode. we designed microchannel size width max 10um, min 5um depth max 10um, reservoir size max 100um, min 2mm. Fabrication of microfluidic devices in glass substrate by glass wet etching methods and glass to glass fusion bonding. The p-i-n diode has higher sensitivity than photodiode, Considering these results, we fabricated p-i-n diodes on the high resistive(4㏀$.$cm) wafer into rectangle and finger pattern and compared internal resistance of each pattern. The internal resistance of pin diode can be decreased by the application of finger pattern has parallel resistance structure from 571Ω to 393Ω.

• Proceedings of the KIEE Conference
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• 2004.07d
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• pp.2616-2618
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• 2004

본 논문에서는 휴대용 선량계 시스템에 대해 논하였다. 휴대용 선량계는 감마선과 속중성자 및 열중성자를 현장에서 실시간으로 측정 할 수 있는 휴대용 선량계이다. 선량계는 선량계의 소형화를 위해 모듈별로 구성하여 공간의 최적화를 취하였다. 모듈의 구성은 시스템의 전반적인 제어를 하는 CPU부 센서로부터 측정한 데이터를 처리하는 신호처리부 방사선량을 측정하는 센서부로 구성되어졌다. 센서 모듈의 PIN 다이오드와 MODFET 센서를 이용하여 감마선, 속중성자, 열중성자를 측정한다. 휴대용 선량계를 관리하고 측정한 데이터의 백업 및 분석을 위하여 PC용 관리프로그램과 블루투스 통신을 사용하여 통신하도록 만들어 사용하였다. 측정 지역의 방사선량을 휴대용 선량계로 측정하여 PC용 관리프로그램에서 방사선량을 확인 할 수 있다.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.7
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• pp.698-703
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• 2007

In this paper, a novel impedance tuner using a directional coupler is proposed. The design topology is analyzed by signal flow graph(SFG) and shows advantages compared with conventional single and double stub methods from the view points of easy implementation and wide tuning range, respectively. This impedance tuner consists of ten switches and its $2^{10}$ tuning points are distributed uniformly on the whole Smith chart. The measured maximum magnitude of the reflection coefficient is 0.9. And the fabricated impedance tuner has a wide bandwidth from 1.8 to 2.2 GHz. Using this impedance tuner, we did a load-pull measurement of a power transistor.

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.4
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• pp.473-477
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• 2015

In this paper, a commercial phosphorescent white light-emitting diode (WLED) visible light communication (VLC) system with an equalization circuit to achieve the high modulation bandwidth was designed and demonstrated. An analytical method to examine the performance of the equalizer was carried out using a general circuit-simulator, PSpice. The equalization circuit was composed of two passive filters with resisters and a capacitor and an active filter with an op-amp. Utilizing our post-equalization technology, the ~3.5 MHz bandwidth of phosphor WLED could be extended to ~25 MHz without using an optical blue-filter. In this VLC system with a single round-type WLED and a single PIN photo-diode, ASK data transmission up to 35 Mbps at a 1m free space distance was obtained. The resulting bit-error-rate was $7.6{\times}10^{-4}$, which is less than the forward error correction (FEC) limit of $3.8{\times}10^{-3}$.

• Journal of the Korean Society of Radiology
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• v.16 no.5
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• pp.519-526
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• 2022

Electronic personal dosimeter (EPD) provide real time monitoring and a direct indication of the accumulated dose or dose rate in terms of personal dose. Most EPD do not perform well in low energy photon radiation fields present in medical radiation environments. It has poor responsibility and large error rate for low energy photon radiation of medical radiation environments. This study evaluated to optimal additional filtration for EPD using silicon PIN photodiode detector form 40 to 120 kVp range in medical radiation environments. From 40 to 80 kVp energy range, Al 0.2 mm and Sn 1.0 mm overlapped filtration showed good responsibility to dose rate and from 80 kVp to 120 kVp energy range, Al 0.2 mm and Sn 1.6 mm overlapped filtration showed good responsibility to dose rate.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.10
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• pp.1137-1144
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• 2012

In this paper, a 2.6 GHz switched parasitic array(SPA) antenna is designed to resolve the device interference in the femtocell. The designed SPA antenna structure consists of a central ${\lambda}/4$ monopole antenna as a radiator and surrounding four parasitic elements operating as a reflector or a director depending on the switching state. In addition, open state monopoles around the parasitic elements are placed to improve the directivity. The designed antenna utilizes RF FETs as switching elements instead of conventional PIN diodes, which enables beam steering with a simple structure consuming low power. To select the proper FET switch, the performance of the SPA antenna depending on the switch characteristics is analyzed. The fabricated antenna has 65 mm radius and 35 mm height, which shows about 15 dB front-back-ratio(FBR) at 2.6 GHz and enables eight-directional beam steering.