• Journal of the Korea Institute of Information and Communication Engineering
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• v.23 no.7
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• pp.807-815
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• 2019

In this paper, we design a power amplifier to support quad-band in wireless communication devices using RF CMOS 180-nm process. The proposed power amplifier consists of low-band 0.9, 1.8, and 2.4 GHz and high-band 5 GHz. We proposed a structure that can support each input matching network without using a switch. For maximum linear output power, the output matching network was designed for impedance conversion to the power matching point. The fabricated quad-band power amplifier was verified using modulation signals. The long-term evolution(LTE) 10 MHz modulated signal was used for 0.9 and 1.8 GHz, and the measured output power is 23.55 and 24.23 dBm, respectively. The LTE 20 MHz modulated signal was used for 1.8 GHz, and the measured output power is 22.24 dBm. The wireless local area network(WLAN) 802.11n modulated signal was used for 2.4 GHz and 5.0 GHz. We obtain maximum linear output power of 20.58 dBm at 2.4 GHz and 17.7 dBm at 5.0 GHz.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.15 no.5
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• pp.335-342
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• 2022

In this paper, a single-bit 3rd-order feedforward delta sigma modulator is proposed for audio applications. The proposed modulator is based on a class-C inverter for low voltage and power applications. For the high-precision requirement, the class-C inverter with regulated cascode structure increases its DC gain and acts as a low-voltage subthreshold amplifier. The proposed Class-C inverter-based modulator is designed and simulated in 180-nm CMOS process. With no performance loss and a low supply voltage compatibility, the proposed class-C inverter-based switched-capacitor modulator achieves high power efficiency. This design achieves an signal-to-noise-and-distortion ratio (SNDR) of 93.9 dB, an signal-to-noise ratio (SNR) of 108 dB, an spurious-free dynamic range (SFDR) of 102 dB, and a dynamic range (DR) of 102 dB at a signal bandwidth of 20 kHz and a sampling frequency of 4 MHz, while only using 280 μW of power consumption from a 0.8-V power supply.

• Journal of Korea Society of Industrial Information Systems
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• v.29 no.3
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• pp.23-40
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• 2024

Hardware attacks involve physical reverse engineering efforts to steal sensitive information, such as encryption keys and circuit designs. Encryption and obfuscation are representative countermeasures, but they are nullified if adversaries manage to find the key. To address this issue, we propose e-Cryptex, which utilizes a Physically Unclonable Function (PUF) as an anti-tampering shield. PUF acts as a random number generator and relies on unique physical variants that cannot be replicated or restored to enhance anti-tampering mechanisms. e-Cryptex uses PUF as a shield to protect the system's structure and generate the key. Tampering with the shield will result in the destruction of the key. This paper demonstrates that e-Cryptex meets PUF security requirements and is effective in detecting of tampering attempts that pierce or completely destroy the shield. Each board consistently generates the same key under normal conditions, while also showing key uniqueness across different boards.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.35D no.11
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• pp.78-84
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• 1998

Refractive index was matched using the inhomogeneous dielectric layers to enhance the optical transmittance of surface discharge type AC PDP. The transmittance of upper panel which had two index-matched inhomogeneous dielectric layers was measured as 85%, and this result is regarded as 15% better transmittance than that of conventional structure, which is about 70%.

• Proceedings of the Acoustical Society of Korea Conference
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• autumn
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• pp.193-196
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• 1999

본 논문은 음향 임펄스를 모델링하는데 코사인 변조된 필터 뱅크와 Decimation을 이용하여 수렴 속도를 개선하는 방법을 제안하고 이를 잡음제거에 응용하였다. 제안된 구조는 입력신호를 필터뱅크를 이용하여 각 서브밴드로 분할한 후 필터 입력신호의 고유벡터의 최대값과 최소값의 비를 줄이고 필터의 탭수를 줄이기 위해서 decimation을 행한다. 그리고 서브밴드대역의 샘플링 주파수를 낮추어 신호 스펙트럼을 확장시켜 이를 적응필터에 입력하여 수렴속도를 향상시켰다. 실험 결과, Colored잡음의 경우 LMS 알고리즘보다 제안된 방법이 MSE(Mean Square Error)는 좋지는 않았다. 실제 음향시스템의 모델링에는 거의 같은 MSE을 갖으며, 수렴 속도에는 모두 빠른 성능을 보였으며, 이를 음질향상에 적용하여 향상된 음질을 얻을 수 있었다.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.9 s.112
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• pp.795-803
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• 2006

In this paper, we studied hierarchical channel coding scheme using unequal error protection method fur consecutively broadcastingservice under the rain attenuation of Ka band satellite broadcasting. Unlike time-sharing methods, which are design for different channel coding scheme in according to different modulation, unequal error protection method is made in such way that minimum distance between signals are different for importance of signals with same modulation. Consequently we proposed optimal method according to performance analysis.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.03a
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• pp.140-140
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• 2003

Ti:LiNbO$_3$ 광 도파로를 이용한 광 변조기의 마이크로파 손실을 감소시키고 RF와 광파의 속도정합의 조건하에서 초고속 광변조의 제작을 위해서는 두꺼운 TW(travelling wave) 전극이 필수적이다 또한, 두꺼운 Au 전극이 우수한 RF 특성을 갖기 위해서는 도금된 Au 전극이 고순도의 작은 grain size를 갖는 도금 층을 제조하여야 하며, 도금 후 Au 층의 뒤틀림 현상이 작아야 한다. 따라서, 본 연구에서는 LiNbO$_3$ 기판 위에 30nm Ni-Cr과 50nm의 Au의 기저 막을 올렸으며 감광제를 이용한 photo-lithography 공정으로 CPW(coplanar waveguide) 구조의 패턴을 약 13$\mu\textrm{m}$의 두께로 형성 한 후 non-cyanidic 액을 이용하여 전류밀도 0.02 - 0.06 mA, bubble 및 non-bubble flow를 조건으로 하여 도금된 Au 전극의 특성을 관찰하였다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.11B
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• pp.1841-1846
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• 2000

광대역 마이크로파 신호의 광전송시 변조과정에서 발생되는 상호잡음 성분의 억제를 위한 다단 직렬구조의 전계흡수 광변조기를 이용한 선형화 방법을 제안하였고 이론적으로 고찰하였다. 바이어스 전압에 따른 신호의 위상 반전이 발생되는 것을 이용하여 두 개의 서로 다른 바이어스 전압과 입력 마이크로파 신호의 전력 차를 이용하여 광대역 시스템의 성능을 좌우하는 IMD2와 IMD3를 동시에 억압시킬 수 있었다. 모의실험을 통하여 최적의 동작조건을 찾은 결과 35dB의 IMD2 억제와 50dB의 IMD3를 동시에 억압시킬 수 있었으며 이에 따라서 약 15dB의 동작영역의 증가를 얻을 수 있었다.

• Proceedings of the KIEE Conference
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• 2008.10b
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• pp.119-120
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• 2008

본 논문에서는 ECMA 표준에 기반한 multi-gigabit packet 수신기를 위한 프레임 검출 방안을 제안한다. ECMA 표준은 60 GHz 대역에서 multi-gigabit 전송률을 달성하기 위하여 버스트 (burst) 송수신 방식을 사용하며 프리앰볼 (preamble)과 데이터 (data)로 이루어진 프레임 (frame)을 통하여 데이터 송수신이 이루어진다. 본 논문에서는 ECMA 표준 중 DBPSK (Differential Binary Phase Shift Keying)와 DQPSK (Differential Quadrature Phase Shift Keying) 그리고 OOK (On-Off Keying) 변조 방식을 지원하는 multi-gigabit 송수신 시스템을 위한 프레임 검출기를 설계하였다. 설계된 프레임 검출기는 동일한 구조 및 동작 방식을 통하여 고려한 모든 변조 방식들을 지원할 수 있을 뿐만 아니라 하드웨어 구현 복잡도가 낮은 장점을 지닌다.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.42 no.2 s.332
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• pp.87-92
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• 2005

In this paper, adaptive bias circuit and PBG structure have been employed to suppress IMD and improve PAE (Power Added Efficiency) of the power amplifier. It is controlling the gate 'dc' bias voltage with the envelope of the input RF signal. and The PBG structure has been employed on the output port of power amplifier . The proposed power amplifier using adaptive bias circuit and PBG has been improved the IMG by 3 dBc, and the average PAE by $35.54\%$, respectively.