• Journal of electromagnetic engineering and science
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• v.13 no.4
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• pp.263-266
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• 2013

A novel compact and low-loss VHF bandpass filter is presented with enhanced stopband performance using metamaterial zeroth order resonator (ZOR) characteristics. An in-line ZOR filter is initially suggested and changed to have transmission zeros (TZs) due to source-load coupling for effective improvement of the isolation from UHF wireless channels. The proposed filter is smaller than 1/10 of the conventional filters in terms of size and has relatively very low insertion loss (< 1 dB for the electromagnetic (EM) simulation and < 3 dB for the measurement) and return loss (<-20 dB) in the passband due to the approximately 80% size reduction and the higher isolation in the stopband due to the TZs. The circuit and EM simulation are in good agreement with the measurements.

• Journal of The Institute of Information and Telecommunication Facilities Engineering
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• v.10 no.3
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• pp.92-97
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• 2011

In this paper, a controller recognizing human gestures using EMG signal is shown. The tiny and band-type controller is developed for image training to excercise the specific area in the body, and uses a dry-type silver fiber electrode easy to be attached or detached itself to a skin. The captured EMG signals are converted to 10-bit digital values via amplification and frequency filtering processes within the controller, and are transmitted to the server by wireless. As the gesture recognition ratio using the proposed controller on biceps is up to 80%, we expect the practical potential of the controller is very promising.

• Proceedings of the IEEK Conference
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• 2007.07a
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• pp.185-186
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• 2007

In this paper, We propose the selective detection scheme based on pulse repetition considering Bit Error Rate (BER) performance and complexity of noncoherent Ultra Wide Band (UWB) systems. To consider system complexity, the proposed scheme transmits the UWB signals by pulse repetition at the transmitter, like the conventional Pulse Repetition Coding (PRC). However, to effectively improve BER performance of the system the proposed scheme performs selective detection by estimating the Signal-to-Noise Ratio (SNR) of the received pulse-repeated signal at the receiver. Hence, the proposed scheme effectively improves BER performance of the noncoherent UWB systems without increase of the system complexity, as compared to the conventional PRC algorithm.

• Journal of The Institute of Information and Telecommunication Facilities Engineering
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• v.4 no.1
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• pp.31-36
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• 2005

In this paper, a planar type bandpass filter in multilayered PCB is presented. The multilayered PCB structure has some advantages on fabricating microwave devices such as the size reduction and ability of tight coupling by folding or embedding. The proposed BPF has two transmission zeros at the both sides of the center frequency by using independent electric and magnetic coupling structure. The designed BPF with four layer teflon PCBs of dielectric constant 2.94 has dimensions of 24x20x1.524 in mm, center frequency of 2.47GHz and bandwidth of about l00MHz. A good agrement is achieved between the measured result and the simulated one. The influences of air gaps between the layers are also analyzed and presented.

• Proceedings of the KAIS Fall Conference
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• 2006.11a
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• pp.208-211
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• 2006

일정한 스펙트럼 민감도와 낮은 스펙트럼 왜곡을 보이고 선형 보간이 용이하다는 장점을 갖는 LSP 파라미터는 음성코덱(codec)이나 인식기에서 음성신호를 분석하여 전송형이나 저장형 파라미터로 변환되어, 주로 저전송률 음성부호화기에 사용된다. 그러나 LPC 계수를 LSP로 변환하는 방법이 복잡하여 계산시간이 많이 소요된다는 단점이 있다. 기존의 LSP 변환 방법 중 음성 부호화기에서 주로 사용하는 real root 방법은 근을 구하기 위해 주파수 영역을 순차적으로 검색하기 때문에 계산시간이 많이 소요되는 단점을 갖는다. 본 논문에서 제안하는 알고리즘은 LSP 분포 특성에 따라 검색구간의 순서와 검색간격을 달리하며, 제1 포만트와 제2 포만트의 연관성을 고려하여 검색구간을 조절한다. 기존의 real root 방법과 제안한 방법을 비교한 결과 검색시간이 평균 48.13% 단축되었다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.12
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• pp.7309-7316
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• 2014

In this paper, a triple-band multiplexer using a microstrip transmission line was designed and fabricated to make use of a low power portable base station. This multiplexer was used in the triple-band including the cellular, WCDMA and LTE mobile frequency band, and designed to have an insertion loss of 0.8 dB, low SWR of 1.5 in the passband and a band rejection of 15 dB in the stopband. From the measured results obtained by a confidence test for the fabricated multiplexer samples, the maximum insertion loss and SWR of the fabricated multiplexer samples in all passbands of 824-894MHz, 1920-2170 MHz and 2500-2600 MHz were below 0.71 dB and 1.38, and the attenuations in the stopbands were better than 15 dB. Therefore, the triple-band multiplexer has good performance and satisfies the design specifications.

• Fire Science and Engineering
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• v.31 no.5
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• pp.117-122
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• 2017

The absence of fire fighters' connection to communication can bring about increased loss of life due to errors and delays in rescue and actions and danger to their own safety. Therefore, when communication infrastructure has been destroyed in an enclosed space, it is necessary to set up an emergency wire or wireless telecommunication environment to fire fighting and to secure safer environment to deal with the disaster by checking the location of fire fighters. In this research, for the establishment communication environment in an enclosed inside using Ultra-Wide Band (UWB) wireless communication network, the performance of communication position determination of a single UWB communication module was evaluated regarding 6 kinds of indoor surroundings. When the communication distance in an indoor environment of each 6 channels bandwidth of UWB communication frequency was measured, the results were as follows: the open space (Ave. 15.5 m, Max. 20 m), the corridor (Ave. 17.33 m, Max 20 m), inside retaining home furnishings (Ave. 15.3 m, Max. 20 m), vertical stairs (Ave. 4.33 m, Max. 6 m), horizontal space with a closed fire door (Ave. 6.5 m, Max. 17 m). It was also found out that the communication function and the distance function were best in the frequency range from 6489.6 to 1081.6 MHz by 7 Ch. Accordingly, the establishment of communication environment in an enclosed space is judged to be possible when UWB communication module is set up at 20 m apart and multiple channels are used.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.7
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• pp.1-7
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• 2016

In this paper, the design methodology of a corrugated conical horn antenna is proposed to be obtain wide-band properties over the full range of frequencies in the Ku-band. In order to improve the properties of the corrugated conical horn antenna, such as its gain, VSWR, co-polarization to cross-polarization ratio and wide-bandwidth, two types of mode matching converters are implemented within it. One is located at the end of the circular waveguide, while the other is positioned in front of the horn-flare section. The properties of the antenna are analyzed and compared according to the position of the proposed converters through simulations. In the comparison of the antenna performance in the case where the VSWR, co-polarization to cross-polarization ratio and antenna gain over the Ku band of 12-18 GHz are less than 2, greater than 30dB and 20dB respectively, the former antenna exhibits greater stability and a wider frequency band than the latter from the viewpoint of transmitting and receiving signals simultaneously. Therefore, considering the gain, VSWR, radiation pattern and bandwidth, the horn antenna structure in which the mode matching converter is implemented inside the circular waveguide has better performance than the other.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.1
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• pp.79-84
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• 2007

In this paper, a fully-integrated low phase noise multi-band CMOS VCO using automatic level controller (ALC) and switched LC tank has been presented. The proposed VCO has been fabricated in a 0.13-um CMOS process. The switched LC tank has been designed with a pair of capacitors and two pairs of inductors switched using MOS switch. By using this structure, four band (2.986 ${\sim}$ 3.161, 3.488 ${\sim}$ 3.763, 4.736 ${\sim}$ 5.093, and 5.35 ${\sim}$ 5.887 GHz) operation is achieved in a single VCO. The VCO with 1.2 V power supply has phase noise of -118.105 dBc/Hz @ 1 MHz at 2.986 GHz and -113.777 dBc/Hz @ 1 MHz at 5.887 GHz, respectively. The reduced phase noise has been approximately -1 ${\sim}$ -3 dBc/Hz @ 1 MHz in the broadest tuning range, 2.986 ${\sim}$ 5.887 GHz. The VCO has consumed 4.2 ${\sim}$ 5.4 mW in the entire frequency band.

• 한국정보통신설비학회:학술대회논문집
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• 2007.08a
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• pp.147-150
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• 2007

This paper presents an advanced RFID reader system implementing multi-protocols and multi-standards at 900MHz. In accordance with the strict regulations specified by ISO 18000-6 B-Type and EPC Global Gen 2, we have designed corresponding systemic factors which meet the domestic radio frequency utilizing bands of 910-914MHz. In addition, we develop numerous crucial factors of system compatibility options including SSB (Single-Side Band) and DSB (Double-Side Band) specifications, also OOK (On-Off Keying), ASK (Amplitude Shift Keying) and PR-ASK (Phase Reversed-Amplitude Shift Keying) modulation formula. Remarkable technical features of system in this paper can be the direct conversion routines using I/Q Modulation/Demodulation respectively, and Full-Duplex formulation operating at identical frequency bands.