• Journal of Institute of Control, Robotics and Systems
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• v.5 no.7
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• pp.800-807
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• 1999

A Periodic disturbance canceller is proposed to compensate for the periodic disturbance due to cutting process in a CNC machining center. The periodic disturbance canceller estimates the Periodic disturbance without phase delay. This is achieved by using linear phase low-pass filter and frequency response reciprocal filter of plant at the frequency of the periodic disturbance. This method is implemented in the position control system of the CNC machining center with general disturbance compensators in order to compensate for both the frictional force and the periodic disturbance. The experimental results are described to show its effectiveness.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.30B no.5
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• pp.34-42
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• 1993

Due to the low loss, broadband and accurate short time delay properties of optical fiber, it has attracted as a delay medium for high speed and broad-band signal processing. In this paper, we consider the coherent optical fiber filter of lattice structure, which uses coherent light sources and consists of directional couplers and optical fiber delay elements.The differences between the optical fiber filter and the ordinary digital filter are 1) the coupling coefficients of directional couplers are restricted between 0 and 1. 2) the optical signal is divided into ${j\sqrt{a}}and\;{j\sqrt{1-a}}$ at the directional coupler. Considering these restrictions, the design formulae and condition of realibility for optical fiber filter of lattice structure which makes the optimal use of optical signal energy are derived.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.21 no.1
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• pp.15-22
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• 2013

In oceanic flight routes, HF radio and satellite data links have weather restrictions, long propagation delay and low data throughput. In this paper, we propose oceanic aeronautical communications scheme in the VHF band based on ad-hoc communication. The proposed scheme organizes autonomously a multi-hop network that is divided into multiple local network using aircraft to fly long-distance communication and supports a hybrid type of multiple access, which consists of random access and TDMA (Time Division Multiple Access) scheme. In addition, several algorithms to apply spatial reuse of transmission to multi-hop long range communication environments have been proposed. The proposed system proves performance improvement on delay time as an effective solution to communicate end-to-end on the oceanic flight routes and strengthens the reliability of oceanic aeronautical communication.

• The Korean Journal of Pain
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• v.22 no.2
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• pp.176-180
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• 2009

Cases of pyogenic spondylodiscitis are relatively rare diseases that concern 2-7% of total cases of osteomyelitis. Owing to the low frequency and initial nonspecific nature of signs and symptoms, diagnosis is often delayed up to 2-6 months. If the proper treatment is not established due to a diagnostic delay, there is a possibility of a serious neurologic deficit and spinal instability. We report two cases of infectious spondylodiscitis which were misdiagnosed as compression fracture and spinal stenosis respectively. They could be correctly diagnosed after MRI and laboratory test and under the recovery state after an antifungal and antibiotic medication. Special careful attention during the diagnostic procedure is a really important step considering the diagnostic delay and its resultant unsatisfactory outcome.

• JSTS:Journal of Semiconductor Technology and Science
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• v.13 no.1
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• pp.71-78
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• 2013

In highly reliable and durable systems, failures due to aging might result in catastrophes. Aging monitoring techniques to prevent catastrophes by predicting such a failure are required. Aging can be monitored by performing a delay test at faster clocks than functional clock in field and checking the current delay state from the test clock frequencies at which the delay test is passed or failed. In this paper, we focus on test clock control scheme for a system-on-chip (SoC) with multiple clock domains. We describe limitations of existing at-speed test clock control methods and present an on-chip faster-than-at-speed test clock control scheme for intra/inter-clock domain test. Experimental results show our simulation results and area analysis. With a simple control scheme, with low area overhead, and without any modification of scan architecture, the proposed method enables faster-than-at-speed test of SoCs with multiple clock domains.

• Proceedings of the KIEE Conference
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• 2000.07b
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• pp.1056-1058
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• 2000

Deadbeat technique has been proposed as a digital controller for an UPS inverter to achieve the fast response to a load variation and to conserve a very low THD under a nonlinear load condition. This scheme contains a fatal drawback, sensitivity against parameter variation and calculation time delay. This paper proposes a second order deadbeat current controller, which fundamentally solves the calculation time delay problem and certainly guarantees the robustness of the parameter's variation. This is shown theoretically and practically through simulation and experiment.

• Proceedings of the KIEE Conference
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• 2004.11a
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• pp.123-125
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• 2004

In order to achieve high efficiency and low cost, new high-speed addressing method is suggested. This can be achieved by reducing the address discharge delay time through the priming effect. This paper suggests a new ADR (Address During Reset) driving method which provides priming particles by using a separated driving method without adding auxiliary electrode or auxiliary discharge. The experimental results show an approximately loons reduction in the formative delay time of address discharge and a reduction in jitter of over 200ns. Also, due to enough time being available for reset, there was a reduction in light emitted during reset of about 29% which improved the dark contrast ratio considerably.

• Journal of Power System Engineering
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• v.10 no.4
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• pp.159-164
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• 2006

In recent, the marine engine of a large size is being realized a lower speed, longer stroke and a small number of cylinders for the energy saving. Consequently the variation of rotational torque became larger than former days because of the longer delay-time in fuel oil injection process and an increased output per cylinder. It was necessary that algorithms have enough robustness to suppress the variation of the delay-time and the parameter perturbation. This paper shows the structure of hybrid F-NFC against the delay-time and the perturbation of engine parameter as modeling uncertainties, and the design of the robust speed controller by hybrid F-NFC for the engine. And, The Parameter values of linear equation are determined by RC-GA for F-NFS. The hybrid F-NFC is combined the F-NFC and PID controller for filling up each.

• Proceedings of the Korean Information Science Society Conference
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• 2007.10b
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• pp.264-268
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• 2007

연결선(interconnect) 사이의 간섭으로 발생하는 crosstalk 지연시간(delay)을 제거하기 위한 두 가지의 방법을 제안 한다. (1) 체계적인 코드를 생성해내는 방법으로 crosstalk 지연시간(delay) 유발 경우를 두 가지의 종류로 분류하여 각각에 대해 버스(bus) 비트 수의 증가에 따른 analytic 한 코드 생성 공식을 유도하였다; (2) 부-버스(sub-bus) 간에 발생하는 crosstalk 지연시간(delay)을 기존의 방법에 비해 보다 효율적으로 제거하는, 즉 추가적인 차단 라인 (또는 complement 비트 라인)를 감소시키는 방법을 제안 한다. 두 연구 결과는 연결선 상의 데이터 전송에 따른 신뢰성, 지연시간 및 전력 소모 증가를 유발하는 crosstalk를 차단하는 엔코딩 기법으로 유용하게 사용될 것으로 보인다.

• Current Optics and Photonics
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• v.3 no.5
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• pp.438-444
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• 2019

In this theoretical study, a line-defect photonic-crystal waveguide hosted in an annular photonic crystal was demonstrated to provide high-performance slow light with a wide band, low group-velocity dispersion, and a large normalized delay-bandwidth product. Combined with structural-parameter optimization and selective optofluid injection, the normalized delay-bandwidth product could be enhanced to a large value of 0.502 with a wide bandwidth of 58.4 nm in the optical-communication window, for a silicon-on-insulator structure. In addition, the group-velocity dispersion is on the order of $10^5$ ($ps^2/km$) in the slow-light region, which could be neglected while keeping the signal transmission unchanged.