• 대한전자공학회논문지SD
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• 제38권2호
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• pp.42-42
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• 2001

본 논문은 주파수 천이를 적용시킨 광무선(fiber-radio)시스템의 광링크부에 대한 성능분석을 한다. 제시된 광링크부는 CS(control station)에서 얻어진 밀리미터파 대역 광파일럿톤(optical pilot tone)이 하향링크뿐 아니라 상향링크에도 공급되도록 하여 BS(base station)의 구조를 간단히 하였다. 광파일럿톤을 얻기 위해 CS의 EOM(electro-optic modulator)을 MAB(maximum bias), MIB(minimum bias), QB(quadrature bias)로 바이어스를 달리할 수 있으며 각각의 경우에 따라 링크의 성능을 분석한다. 분석은 레이저 광원의 전력이 일정한 경우와 PD(photo detector)에 수신되는 광 DC 전력이 일정한 경우에 대해서 행하여지며 각 경우에 대해서 최적의 하향링크 CNR 및 상향링크 SFDR(spurious free dynamic range)을 얻기 위해 효과적인 바이어스 방식을 제시한다

• 전자공학회논문지A
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• 제33A권7호
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• pp.111-120
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• 1996

In this paper, we proposed an inductance loaded small type open-loop travelling wave antenna model for the suitable VHF/UHF frequency bands moisture measurement systems and analyzed its operating characteristics by galerkin's solution method. This antenna model enables to change the oeprating rsonance frequency from the frequency range 150 Mhz to 1.0 Ghz without changing the antenna design dimensions by only varing the load inductance values and it showed the similar operating charcteristics and narrowband resonance characteristics at each resonance frequencies. Also this model showed the uniformly distriubte dpower radiation characteristics above the loop axis and it can effectively suppress the spurious radiations from its narrowband resonance characteristics.

• IEIE Transactions on Smart Processing and Computing
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• 제3권4호
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• pp.161-166
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• 2014

An accurate gain-of-two amplifier, which successfully reduces the capacitor mismatch error is proposed. This amplifier has similar circuit complexity and linearity improvement to the capacitor error-averaging technique, but operates with two clock phases just like the conventional pipeline stage. This makes it suitable for high-speed, high-resolution analog-to-digital converters (ADCs). Two ADC architectures employing the proposed accurate gain-of-two amplifier are also presented. The simulation results show that the proposed ADCs can achieve 15-bit linearity with 8-bit capacitor matching.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1999년도 봄 학술발표회 논문집
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• pp.234-241
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• 1999

In this study, an improved 8-node flat shell element is presented for the analysis of shell structure, by combining 8-node membrane element with drilling degree-of-freedom and 8-node plate bending element based on the recently presented technique. Firstly, 8-node membrane element designated as CLM8 is presented in this paper. The element has drilling degree-of.freedom in addition to transitional degree-of-freedom. Therefore the element possesses 3 degrees-of-freedom per each node which as well as the improvement of the element behavior, permits an easy connection to other element with rotational degree-of -freedom. Secondly. 8-node flat shell element was composed by adding 8-node Mindlin plate bending element to the membrane element. The behavior of the introduced plate bending element is further improved by combined use of nonconforming displacement modes, selectively reduced integration scheme and assumed shear strain fields. The element passes in the patch test, doesn't show spurious mechanism and doesn't produce shear locking phenomena. Finally, Numerical examples are presented to show the performance of flat shell element developed in the present study.

• Structural Engineering and Mechanics
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• 제18권5호
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• pp.671-690
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• 2004

An assumed strain finite strip method(FSM) using the non-periodic B-spline for a shell is presented. In the present method, the shape function based on the non-periodic B-splines satisfies the Kronecker delta properties at the boundaries and allows to introduce interior supports in much the same way as in a conventional finite element formulation. In the formulation for a shell, the geometry of the shell is defined by non-periodic B3-splines without any tangential vectors at the ends and the penalty function method is used to incorporate the drilling degrees of freedom. In this study, new assumed strain fields using the non-periodic B-spline function are proposed to overcome the locking problems. The strip formulated in this way does not posses any spurious zero energy modes. The versatility and accuracy of the new approach are demonstrated through a series of numerical examples.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2010년도 추계학술대회
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• pp.371-374
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• 2010

In this article, new microstrip slow-wave bandpass filters using open loop resonator loaded with inter-digital capacitive fingers is proposed. The filter features not only compact in size, but also exhibits spurious stop-band rejection. Filters of this type with elliptic function and Chebyshev response are demonstrated. There is good agreement between experimental and full-wave electromagnetic (EM) simulation results.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2001년도 ICCAS
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• pp.156.1-156
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• 2001

It is observed that if the 2-gimballed seeker is stabilized using rate gyros mounted along its primary axis, line of sight change measured in the seeker is induced by the rolling due to the bank-to-turn(BTT) steering as well as the actual change. This body-coupling within BTT homing includes the spurious target maneuver effect and the coupling loop due to the rate gyro misalignment. In this paper we formulates the linear BTT homing loop model with a 2-gimballed seeker including those body-coupling effects. With the model, we analyze the effects of the couplings, and show that the roll rate coupling to the rate gyro for the stabilztion of gimbal could seriously deteriorate the homing loop stability. And we propose a direct linear compensator for the coupling to recover the stability.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 하계종합학술대회 논문집(2)
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• pp.133-136
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• 2002

This paper discusses the design of a sample-and -hold amplifier(SHA) that has a 12-bit resolution with a 100 MS/s speed. The sample-and-hold amplifier uses the open-loop architecture with hold-mode feedthrough cancellation for high accuracy and high sampling speed. The designed SHA is composed of input buffer, sampling switch, and output buffer with additional amplifier for offset cancellation Hard Ware. The input buffer is implemented with folded-cascode type operational transconductance Amplifier(OTA), and sampling switch is implemented with switched source follower(SSF). A spurious free dynamic range (SFDR) of this circuit is 72.6 dB al 100 MS/s. Input signal dynamic range is 1 Vpp differential. Power consumption is 65 ㎽.

• 전자공학회논문지A
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• 제33A권5호
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• pp.75-84
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• 1996

planar circulator swith arbitrarily shaped ferrite resonators are analyzed in this paper. First, resonant frequencies and field distributions for the magnetized ferrite resonator are obtained using finite element method (FEM). Then the RF voltage distributions and other circuit parameters of the circulator which is formed by connecting three suitable transmission lines ot the ferrite resonator are derived from the green function . To remove the spurious solutions in analyzing the ferrite resonator, the results of eigenvalue analysis by node based FEM are comapred with the edge based fEM. The green function is expanded in terms of normalized eigenfunctions of th ecorresponding wave equation. Circulator parameters for circular disk resonator are clculated and compared with the analytical results. The experimental data for the designed circulator using hexagonal reosnator in the 850 MHz frequency range agree well iwth the simulated data.

• ETRI Journal
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• 제34권4호
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• pp.518-526
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• 2012

This paper proposes LC voltage-controlled oscillator (VCO) phase-locked loop (PLL) and ring-VCO PLL topologies with low-phase noise. Differential control loops are used for the PLL locking through a symmetrical transformer-resonator or bilaterally controlled varactor pair. A differential compensation mechanism suppresses out-band spurious tones. The prototypes of the proposed PLL are implemented in a CMOS 65-nm or 45-nm process. The measured results of the LC-VCO PLL show operation frequencies of 3.5 GHz to 5.6 GHz, a phase noise of -118 dBc/Hz at a 1 MHz offset, and a spur rejection of 66 dBc, while dissipating 3.2 mA at a 1 V supply. The ring-VCO PLL shows a phase noise of -95 dBc/Hz at a 1 MHz offset, operation frequencies of 1.2 GHz to 2.04 GHz, and a spur rejection of 59 dBc, while dissipating 5.4 mA at a 1.1 V supply.