• JSTS:Journal of Semiconductor Technology and Science
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• 제8권3호
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• pp.179-192
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• 2008

A multiphase compensation method with mismatch linearization technique, is presented and demonstrated in a $\Sigma-\Delta$ fractional-N frequency synthesizer. An on-chip delay-locked loop (DLL) and a proposed delay line structure are constructed to provide multiphase compensation on $\Sigma-\Delta$ quantizetion noise. In the delay line structure, dynamic element matching (DEM) techniques are employed for mismatch linearization. The proposed $\Sigma-\Delta$ fractional-N frequency synthesizer is fabricated in a $0.18-{\mu}m$ CMOS technology with 2.14-GHz output frequency and 4-Hz resolution. The die size is 0.92 mm$\times$1.15 mm, and it consumes 27.2 mW. In-band phase noise of -82 dBc/Hz at 10 kHz offset and out-of-band phase noise of -103 dBc/Hz at 1 MHz offset are measured with a loop bandwidth of 200 kHz. The settling time is shorter than $25{\mu}s$.

• 한국군사과학기술학회지
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• 제12권1호
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• pp.106-113
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• 2009

This paper presents a surface acoustic wave(SAW) micro-electro-mechanical-systems(MEMS) interdigital transducer (IDT) gyroscope with 80MHz central frequency on a $128^{\circ}\;YX\;LiNbO_3$, which is consisted of a two-port SAW resonator, metallic dots and dual delay lines for the sensor and reference oscillators. Reason for using two delay line oscillators is to extract the gyroscope effect by comparing the resonant frequencies between two oscillators and to compensate the temperature effect. Based on the coupling of modes(COM) simulation, an 80MHz two ports SAW resonator and dual delay line were fabricated and characterized by the network analyzer. Obtained sensitivity was $109Hz/deg{\cdot}s^{-1}$ in the angular rate range of $0{\sim}1000deg/s$. Good Linearity and superior directivity were observed.

• 한국광학회지
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• 제30권3호
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• pp.94-100
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• 2019

본 연구에서는 광 지연선로를 이용한 스퀸팅(squinting)이 없는 위상배열 안테나의 근접장 미세파장 포커싱(subwavelength focusing)을 디자인하고 전산모사를 통해 검증하였다. 마이크로파 파장에서 위상배열 안테나의 수치적 계산을 위해 호이겐스-프레넬(Huygens-Fresnel) 원리를 적용하였다. 제안하는 시스템은 첩 광섬유 격자(chirped fiber grating)에 기반한 광 지연선로를 이용하여 빔 스퀸팅이 생기지 않는다는 것을 전산모사를 통해 확인하였다. 그리고 개별 안테나의 배열은 광학렌즈시스템에서 회절 소자로 간주할 수 있음에 착안해 높은 개구율(numerical aperture)을 구현하고 미세파장 포커싱을 얻었다. 또한, 위상배열 안테나의 안테나 사이 거리를 반파장 이하로 줄여 사이드 로브를 억제할 수 있음을 보였다.

• 한국음향학회지
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• 제27권8호
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• pp.427-434
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• 2008

본 논문에서는 SMV와 AMR 음성부호화기를 위한 상호부호화 알고리즘을 제안한다. 각기 다른 통신망에서 음성부호화기간의 효율적인 연동을 위해 가장 간단한 방법인 tandem 방식이 있지만 긴 지연시간과 많은 연산량, 그리고 음질 저하의 문제점들을 해결하기위해 상호부호화 방법을 사용한다. 제안하는 상호부호화 알고리즘은 LSP (Line Spectral Pairs) 변환, 피치 변환, 그리고 고속 고정 코드북 탐색을 수행한다. 실험 결과, $20\sim50%$의 적은 계산량과 $5\sim10$ ms의 지연 시간을 줄이면서도 동등한 음질을 확인할 수 있었다.

• 한국군사과학기술학회지
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• 제16권2호
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• pp.191-198
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• 2013

Geo-pointing is a function that maintains LOS(Line of Sight) to a stationary ground target by controlling azimuth and elevation angles of a EOS(Electro-Optical System) which are calculated from aircraft navigation data and target coordinates. In design and implementation of the geo-pointing, a transmission time delay between GPS/INS and EOS is a major degradation factor of the geo-pointing performance when the aircraft is rapidly maneuvered especially. In this paper, a kalman filter is designed to compensate the transmission time delay of aircraft navigation data. Simulation and test results show that the geo-pointing performance is enhanced by the proposed compensation technique.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2005년도 추계종합학술대회
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• pp.829-832
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• 2005

This paper describes a wide-range dual-loop Delay Locked Loop (DLL) using Voltage Controlled Delay Line (VCDL) based on Transmission Gate(TG) inverters. One loop is used when the minimum VCDL delay is greater than a half of $T_{REF}$, the reference clock period. The other loop is initiated when the minimum delay is less than $0.5{\times}T_{REF}$. The proposed VCDL improves the dynamic operation range of a DLL. The DLL with a VCDL of 10 TG inverters provides a lock range from 70MHz to 700MHz when designed using $0.18{\mu}m$ CMOS technology with 1.8 supply voltage. The DLL consumes 11.5mW for locking operation with a 700MHz reference clock. The proposed DLL can be used for high-speed memory devices and processors, communication systems, high-performance display interfaces, etc.

• 한국컴퓨터정보학회논문지
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• 제4권2호
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• pp.105-112
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• 1999

확산대역통신은 CDMA 시스템에서의 핵심기술이지만 SS통신에서의 문제점은 동기 방법이다. 동기방법에는 DLL(Delay Lock Loop), Tau-dither Loop, SO(Synchronous Osillator) 등이 있다. 그러나 아날로그 동작시에는 회로의 크기가 커지고 조정이 어려운 문제가 있어 본논문에서는 Digital Delay Lock Loop (DDLL)을 제안하고 실험을 통해 그 성능을 평가하였다.

• ETRI Journal
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• 제28권1호
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• pp.31-44
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• 2006

In a packet switching network, congestion is unavoidable and affects the quality of real-time traffic with such problems as delay and packet loss. Packet fair queuing (PFQ) algorithms are well-known solutions for quality-of-service (QoS) guarantee by packet scheduling. Our approach is different from previous algorithms in that it uses hardware time achieved by sampling a counter triggered by a periodic clock signal. This clock signal can be provided to all the modules of a routing system to get synchronization. In this architecture, a variant of the PFQ algorithm, called digitized delay queuing (DDQ), can be distributed on many line interface modules. We derive the delay bounds in a single processor system and in a distributed architecture. The definition of traffic contribution improves the simplicity of the mathematical models. The effect of different time between modules in a distributed architecture is the key idea for understanding the delay behavior of a routing system. The number of bins required for the DDQ algorithm is also derived to make the system configuration clear. The analytical models developed in this paper form the basis of improvement and application to a combined input and output queuing (CIOQ) router architecture for a higher speed QoS network.

• 제어로봇시스템학회논문지
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• 제9권3호
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• pp.196-203
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• 2003

Recent increase in accessibility to the internet makes it easy to use the internet-connected devices. The internet could allow any user can reach and command any device that is connected to the network. But these teleoperation systems using the internet connected device have several problems such as the network time delay, data loss and development cost of an application for the communication with each other. One feasible solution is to use local and external network line for the network time delay, transmission control protocol for data loss and Java language to reduce the development period and cost. In this study, web-based remote control system using Java language is newly proposed and implemented to a pneumatic servo control system to solve the time delay, data loss and development cost. We have conducted several experiments using pneumatic rodless cylinder through the internet and verified that the proposed remote control system was very effective.

• 대한수학회보
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• 제58권3호
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• pp.669-688
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• 2021

The aim of this paper is to prove the existence of an admissible inertial manifold for mild solutions to infinite delay evolution equation of the form $$\{{\frac{du}{dt}}+Au=F(t,\;u_t),\;t{\geq}s,\\\;u_s({\theta})={\phi}({\theta}),\;{\forall}{\theta}{\in}(-{{\infty}},\;0],\;s{\in}{\mathbb{R}},$$ where A is positive definite and self-adjoint with a discrete spectrum, the Lipschitz coefficient of the nonlinear part F may depend on time and belongs to some admissible function space defined on the whole line. The proof is based on the Lyapunov-Perron equation in combination with admissibility and duality estimates.