• 한국통신학회논문지
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• 제33권7A호
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• pp.751-756
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• 2008

In this paper, we propose a modified I/Q diversity scheme receiver of UHF RFID reader system. The modified I/Q diversity receiver is more robust than the conventional homodyne receiver in the wireless noisy, fading channel and phase noise environments by making use of additional axes. In particular, it is shown that the closer the phase difference ${\theta}(t)$ between the reader and the tag to ${\pi}/4$, the larger performance improvement we can get. The performance of the proposed receiver is verified by equations and is demonstrated by the computer simulation for various difference ${\theta}(t)$ cases.

• Journal of Electrical Engineering and Technology
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• 제7권4호
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• pp.570-575
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• 2012

In a wireless communication RF transmitter, the output of a quadrature modulator (QM) is distorted by not only the linear imperfection features such as in/quadrature-phase (I/Q) input gain imbalance, local phase imbalance, and local gain imbalance but also the nonlinear imperfection features such as direct current (DC) offset and mixer nonlinearity related to in-band spurious signal. In this paper, we propose the unified QM model to analyze the combined effects of the linear and nonlinear imperfection features on the performance of the QM. The unified QM model consists of two identical nonlinear systems and modified I/Q inputs based on the two-port nonlinear mixer model. The unified QM model shows that the output signals can be expressed by mixer circuit parameters such as intercept point and gain as well as the imperfection features. The proposed approach is validated by not only simulation but also measurement.

• 한국군사과학기술학회지
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• 제9권3호
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• pp.48-55
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• 2006

This paper describes the antenna based GPS anti-jamming technology called CRPA(Controlled Reception Pattern Antenna), which used $2{\times}2$ array elements. In this system, the main functions are the antenna complex weight control and the GPS digital I/Q VM(Vector Modulator). To update the VM's I/Q complex weights, the PC based DAC(Digital to Analog Converter) module was also used and the two analog output voltages were applied to the $2{\times}2$ array elements to synthesize the null pattern. In the study, we also simulated the $2{\times}2$ GPS array null patterns to compare the null depth with experimental results. The VM was also modified at the frequency of 1.575GHz for the GPS L1 and controlled by the PC based VM software.

• 한국인터넷방송통신학회논문지
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• 제22권1호
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• pp.7-13
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• 2022

RF-Fingerprint 기술은 전송된 파형에서 송신기의 하드웨어 고유 특성을 추출하는 기술로써, 디바이스 보안 분야에 매우 유용한 기술 중의 하나이다. 본 논문은 무선 단말기의 In-phase(I)와 Quadrature(Q) 값을 입력으로 동종 무선 단말기 및 이기종 무선 단말기를 식별할 수 있는 fingerprint 특징을 추출하고 이를 식별할 수 있는 딥러닝 구조를 제안한다. 동종/이기종 무선 단말기를 식별하기 위한 특징으로 I/Q를 극좌표로 변환한 후 크기 값을 시간축으로 배열한 데이터를 무선 단말기의 fingerprinting 특징으로 제안하고 이를 식별하기 위해서 수정된 1차원 ResNet 모델을 제안한다. 실험을 위해서 동일 모델 10대의 두 종류 무선 단말기를 대상으로 제안한 딥러닝 구조의 성능을 분석한다. 제안한 딥러닝 구조 및 fingerprint 특징의 성능 검증을 위해서 4000개의 데이터셋 중에서 20%인 800개 데이터셋을 이용하여 성능 분석한 결과 약 99.5%의 식별 성능을 보였다.

• The Journal of Korean Physical Therapy
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• 제15권3호
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• pp.265-276
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• 2003

This study was to investigate the dffects of a color reversal visual perceptual training program on spastic cerebral palsied children's figure-ground discrimination disabilities and to investigate the difference between the control group and experimental group. Subjects of the study were composed of children with spastic cerebral palsy whose age varied from five to seven years old, whose I.Q. was over 70 and whose P.Q. was over 70. Implication of this study can be summarized as follows; First, Perceptual training and speech training programs should be emphasized to improve the preparative ability of spastic cerebral palsied children. Problems of perception cerebral palsied children are concerned with figure-ground discrimination disability. Second, Though it was demonstrated that color reversal visual perceptual training program can be effective through the prestudies and this study, more researches should be made to apply this kind of theory in real education environments. More interest in different color forms for training of cerebral palsied children should be taken. Third, Reprecations of the study should be considered with modified group identities(age, I.Q., P.Q.).

• 대한수학회지
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• 제33권4호
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• pp.763-775
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• 1996

For $Q = [0,S] \times [0,T]$ let C(Q) denote Yeh-Wiener space, i.e., the space of all real-valued continuous functions x(s,t) on Q such that x(0,t) = x(s,0) = 0 for every (s,t) in Q. Yeh [10] defined a Gaussian measure $m_y$ on C(Q) (later modified in [13]) such that as a stochastic process ${x(s,t), (s,t) \epsilon Q}$ has mean $E[x(s,t)] = \smallint_{C(Q)} x(s,t)m_y(dx) = 0$ and covariance $E[x(s,t)x(u,\upsilon)] = min{s,u} min{t,\upsilon}$. Let $C_\omega \equiv C[0,T]$ denote the standard Wiener space on [0,T] with Wiener measure $m_\omega$. Yeh [12] introduced the concept of the conditional Wiener integral of F given X, E(F$\mid$X), and for case X(x) = x(T) obtained some very useful results including a Kac-Feynman integral equation.

• 한국전자파학회논문지
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• 제15권7호
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• pp.661-668
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• 2004

본 논문은 위버구조 low-IF 송신부를 구성하는 위버구조 혼합기의 출력단에 나타나는 스퓨리어스 신호를 제거하기 위한 방법을 제안한다. 스퓨리어스 신호는 고주파 혼합기를 사용한I/Q경로 신호의 이득 및 위상 부정합 그리고 I/Q신호를 위한 국부 발진기의 90$^{\circ}$ 위상 부정합에 의해 위버구조 혼합기의 출력단에 나타난다. 고주파 I/Q 경로 신호의 부정합은 스퓨리어스 신호로부터 진폭 부정합과 위상 부정합으로 유도되어 진폭 및 위상 부정합 정도에 의한 부호와 크기 함수로 검출하였다. 제안된 방법은 low-IF상향 혼합기의 출력단에 나타나는 송신 신호를 부정합 검출 회로의 고주파 혼합기에 공급하여 얻어지는 하향 변환된 기저대역 신호와 디지털 신호 처리부에서 수정된 기저 대역 신호와의 상관도를 구하여 진폭 및 위상 부정합을 보상하고 스퓨리어스 신호를 제거한다. 진폭 및 위상 부정합의 크기와 부호는 A/D 변환 후에 디지털 영역에서 독립적으로 결정되며, 부정합의 크기와 부호를 이용하여 디지털 신호 처리부에서 I/Q 경로 신호의 크기와 위상을 연속적으로 조절하여 스퓨리어스 신호를 제거한다. 본 논문에서는 수식적 해석과 성능 시뮬레이션 통하여 제안된 방법의 타당성을 검증하였다.

• Journal of Photoscience
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• 제4권3호
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• pp.97-103
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• 1997

The effect of temperature on the fluorescence quenching of 2-(4-Methoxyphenyl)-5-(1-naphthyl)-1,3,4-oxadiazole (MPNO1), 2-(4-Methoxyphenyl)-5-(2-naphthyl)-1,3,4-oxadiazote(MPNO2), by aniline, and 2-Phenylindole (2-PI) by CCk, in toluene by steady state method and in benzene by time-resolved method have been carried out in the temperature range 30 - 70$\circ$C. The Stem-Volmer (S-V) plots, I$_0$/I against quencher concentration [Q] at different temperanares show positive deviations. The fluorescence lifetimes determined at different temperatures show no systematic variations and the variations being within the experimental error, the average values of lifetimes $ $\tau$ (t) are taken for further calculations. Rate constants such as Stem-Volmer quenching constants K$_sv}$, quenching rate parameters k$_q$ and k'$_q$, static quenching constant V and kinetic distance r are determined using the modified Stem-Volmer equation and sphere of action static quenching model. In order to see whether the reactions are diffusion limited, equations k$_q$ = e$^{-Eq/RT}$ and k'$_q$ = e$^{-Eq/RT}$ are used to determine the values of E$_q$ and E'$_q$, the activation energies for collisional quenching and the values of E$_q$ are 14.53. 17.28 and 16.20 kJ mole$^{-1}$ for MPNO1, MPNO2 and 2-PI respectively and the values of E'$_q$ are 14.62 and 17.73 for MPNO1 and MPNO2 respectively. From the magnitudes of various quantities it has been concluded that the reactions are diffusion limited and the observed positive deviations in the S-V plot are due to static and dynamic quenching.

• ETRI Journal
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• 제36권6호
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• pp.924-930
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• 2014

This paper presents a $0.13{\mu}m$ CMOS 3-level envelope delta-sigma modulation (EDSM) RF signal generator, which synthesizes a 2.6 GHz-centered fully symmetrical 3-level EDSM signal for high-efficiency power amplifier architectures. It consists of an I-Q phase modulator, a Class B wideband buffer, an up-conversion mixer, a D2S, and a Class AB wideband drive amplifier. To preserve fast phase transition in the 3-state envelope level, the wideband buffer has an RLC load and the driver amplifier uses a second-order BPF as its load to provide enough bandwidth. To achieve an accurate 3-state envelope level in the up-mixer output, the LO bias level is optimized. The I-Q phase modulator adopts a modified quadrature passive mixer topology and mitigates the I-Q crosstalk problem using a 50% duty cycle in LO clocks. The fabricated chip provides an average output power of -1.5 dBm and an error vector magnitude (EVM) of 3.89% for 3GPP LTE 64 QAM input signals with a channel bandwidth of 10/20 MHz, as well as consuming 60 mW for both channels from a 1.2 V/2.5 V supply voltage.

• 한국물환경학회지
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• 제23권3호
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• pp.309-313
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• 2007

In Activated Sludge Model, COD fraction of primary settled municipal wastewater was a very important parameter. In this study, the COD fraction was determined using the oxygen utilization rate experiments. Readily biodegradable COD ($S_S$) fraction was observed about 29.7% of influent TCOD. $S_I$, $X_I$, and $X_S$ were analyzed to be 7.6%, 7.3%, and 55.4% of TCOD, respectively. The model used in this study was developed based on ASM3 and modified Bio-P module in order to simulate the existing BNR process. Parameter estimation results showed that $Y_{STO,O2}$, $Y_{STO,NO}$, $Y_{H,O2}$, $Y_{H,NO}$, $Y_{PO4}$, ${\mu}_H$, $b_H$, ${\mu}_A$, $q_{PHA}$, $q_{PP}$ and ${\mu}_{PAO}$ were 0.7, 0.64, 0.61, 0.48, 0.31, 3.9, 0.1, 1.35, 4.98, 1.8 and 0.59, respectively. Using the presented model and the estimated parameters, the simulation of the existing BNR process was successfully conducted.