• 융합신호처리학회논문지
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• 제18권2호
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• pp.55-61
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• 2017

전파천문분야에서 관측데이터의 저장을 위해 대용량 HDD를 RAID로 연결한 디스크 팩을 활용하고 있다. VLBI 관측의 경우 관측속도가 빨라지고 광대역으로 확장되면서 많은 양의 관측데이터를 저장해야 한다. HDD는 사용회수가 많아질수록 고장이 많이 발생하고 있으며, 이것을 찾아서 복구하는데 많은 시간이 소요된다. 또한 고장난 HDD를 계속 사용할 경우 관측데이터의 손실이 발생한다. 그리고 새 HDD를 구입하여 많은 비용도 필요하게 된다. 본 연구에서는 FirmOS를 이용하여 SATA HDD의 무결성 검사 시스템을 개발하였다. FirmOS는 일반 서버보드와 CPU를 갖는 시스템에서 특정목적에만 동작하도록 개발한 OS이다. 개발한 시스템은 FirmOS 기반에서 SATA HDD의 물리적인 영역에 특정 패턴의 데이터를 쓰고 읽는 과정을 수행한다. 그리고 HDD 제어기의 메모리 영역에서 HDD로부터 읽어들인 저장된 패턴 데이터와 비교를 수행하는 방식으로 HDD의 무결성 검사를 확인하는 방법을 채용하였다. 개발한 시스템을 활용하여 VLBI 관측에서 활용하고 있는 디스크 팩의 고장여부를 쉽게 확인할 수 있었으며, 관측효율을 향상시킬 수 있는데 많은 도움이 되고 있다. 본 논문에서는 개발한 SATA HDD 무결성 확인 시스템의 설계, 구성, 시험 등에 대해 자세히 기술한다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2010년도 춘계학술대회 논문집
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• pp.288-289
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• 2010

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2000년도 추계종합학술대회 논문집(1)
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• pp.279-282
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• 2000

As digital systems continue to use components with faster edge rates and clock speeds, transmission of the digital information in these systems approaches the microwave realm. At these speeds digital signal fidelity becomes both a critical success factor and design challenge. The noise sources in digital systems include the noise in power supply, ground and packaging media due to simultaneous switching of drivers, signal reflections and distortions on single and multiple transmission lines. This paper presents theory, case studies and design considerations of gigabit interconnection for network and communication systems. The case studies show HSPICE and Ampredictor simulations of alternate approaches. Various subjects including skin effect and dielectric losses, interconnect simulations and crosstalks of connector, affected signal discontinuity, are addressed.

• 한국생산제조학회지
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• 제20권3호
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• pp.304-309
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• 2011

A monitoring system for magnetic abrasive polishing process is necessary to ensure the polishing products the high quality and integrity. Acoustic emission (AE) signal is known to reflect the material removal phenomena in other machining processes. In a case of the magnetic abrasive polishing of non-magnetic materials, application of AE method is very difficult because of lower machining force on the surface of workpiece and the level of AE signal is extremely lower. In this study, AE sensor-based monitoring system is applied to the magnetic abrasive polishing. The relation between the level of the AE RMS and the surface roughness during the magnetic abrasive polishing of magnesium alloy steel is investigated.

• 대한전자공학회논문지SD
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• 제41권2호
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• pp.77-83
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• 2004

on-chip 상에서 발생하는 누화 잡음은 신호의 충실성을 위협하는 매우 중요한 요소이다. 따라서 본 논문에서는 최대 누화잡음의 크기를 예측하는 해석적인 방법을 제안한다. 정확한 잡음 수치를 예측하기 위해 연결선의 인덕턴스 성분을 고려하였고, 임의의 램프입력을 사용하였다. 또한 복잡한 누화 잡음 모형에서 최대 누화 잡음을 해석적으로 간단히 구하기 위해 가상의 소스 개념을 도입하였다. 된 연구에서 제안한 방법은 HSPICE 시뮬레이션 결과와 비교하여 최대 상대오차 4.3％ 이내의 정확도를 보였다. 따라서 본 연구는 신호 충실성 보장을 위한 다양한 설계 보조 도구 개발에 활용될 수 있을 것으로 본다.

• 대한전자공학회논문지SD
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• 제45권10호
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• pp.39-44
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• 2008

스캔 테스트 기법은 효과적인 테스트 성능 향상 기법이지만, 이를 위한 테스트 수행 시간이 너무나 길어진다는 단점이 있다. 본 논문에서는 동일한 테스트 입력을 이용하는 Illinois 스캔 기법을 기반으로 한 효율적인 스캔 테스트 기법을 제안한다. 제한하는 방안은 다수의 스캔 입력에 선택적으로 접근하여 다중 스캔 기법의 효과를 최대한으로 이용한다. 실험 결과는 제안하는 방안이 입력을 공유하기 위한 효율을 극대화 하여 매우 적은 테스트 시간과 테스트 데이터만을 필요로 함을 보여준다.

• 한국군사과학기술학회지
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• 제13권5호
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• pp.793-800
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• 2010

GPS spoofing is an intentional interference which uses the mimic GPS signals to fake the receivers. The generic GPS receiver is hard to recognize the spoofing signal because the spoofer generates the fake signals as close as possible to the GPS signal. So the spoofer can do critical damage to public operations. This paper introduces a basic concept of spoofing and analyzes the effect of the spoofing signal to the GPS receiver. Also for stand-alone GPS receivers, two anti-spoofing methods are implemented : RAIM based method and the SQM based method. To evaluate the performance of anti-spoofing method, the software based spoofing signal generator and GPS signal generator are implemented. The performance of the anti-spoofing methods obtained using the output of the software based GPS receiver shows that SQM based method is more effective when multiple spoofing signals exist.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2006년도 International Symposium on GPS/GNSS Vol.1
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• pp.235-240
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• 2006

The paper will give an overview of the mission of GalTeC and then concentrate on two main aspects. The first more detailed aspect, is the analysis of the key performance parameters for the Galileo system services and presenting a technical overview of methods and algorithms used. The second more detailed aspect, is the service volume prediction including service dimensioning using the Prediction tool. In order to monitor and validate the Galileo SIS performance for Open Service (OS) and Safety Of Life services (SOL) regarding the key performance parameters, different analyses in the SIS domain and User domain are considered. In the SIS domain, the validation of Signal-in-Space Accuracy SISA and Signal-in-Space Monitoring Accuracy SISMA is performed. For this purpose first of all an independent OD&TS and Integrity determination and processing software is developed to generate the key reference performance parameters named as SISRE (Signal In Space Reference Errors) and related over-bounding statistical information SISRA (Signal In Space Reference Accuracy) based on raw measurements from independent sites (e.g. IGS), Galileo Ground Sensor Stations (GSS) or an own regional monitoring network. Secondly, the differences of orbits and satellite clock corrections between Galileo broadcast ephemeris and the precise reference ephemeris generated by GalTeC will also be compared to check the SIS accuracy. Thirdly, in the user domain, SIS based navigation solution PVT on reference sites using Galileo broadcast ephemeris and the precise ephemeris generated by GalTeC are also used to check key performance parameters. In order to demonstrate the GalTeC performance and the methods mentioned above, the paper presents an initial test result using GPS raw data and GPS broadcast ephemeris. In the tests, some Galileo typical performance parameters are used for GPS system. For example, the maximum URA for one day for one GPS satellite from GPS broadcast ephemeris is used as substitution of SISA to check GPS ephemeris accuracy. Using GalTeC OD&TS and GPS raw data from IGS reference sites, a 10 cm-level of precise orbit determination can be reached. Based on these precise GPS orbits from GalTeC, monitoring and validation of GPS performance can be achieved with a high confidence level. It can be concluded that one of the GalTeC missions is to provide the capability to assess Galileo and general GNSS performance and prediction methods based on a regional and global monitoring networks. Some capability, of which first results are shown in the paper, will be demonstrated further during the planned Galileo IOV phase, the Full Galileo constellation phase and for the different services particularly the Open Services and the Safety Of Life services based on the Galileo Integrity concept.

• 전기학회논문지
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• 제60권1호
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• pp.201-204
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• 2011

For efficient noise reduction in a Fourier transform ion cyclotron resonance (FT-ICR) mass spectrum, a new algorithm was proposed. The suggested algorithm reduces white and electrical noise, and it improves signal-to-noise ratio. This algorithm has been optimized to reduce the noise more efficiently using the traces of signal level. The algorithm has been efficiently combined with derivative window to improve the resolution as well S/N. Time domain data was corrected for DC voltage interference. $t^n$ window was applied in time domain data to improved the resolution. However, $t^n$ window can improve the signal resolution, it will also increase the noise level in frequency domain. Therefore, newly developed noise reduction algorithm will be applied to make a balance between resolving power and S/N ratio for magnitude mode. The trace algorithm can determine the current data point with several data points (mean, past data, calculated past data). In the current calculations, we assumed data points with S/N ratio more than 3 were considered as signal data points. After the windowing and noise reduction, both resolution and signal-to-noise ratio were improved. This algorithm is applicable more efficiently to frequency dependent noise and large size data.

• 대한임베디드공학회논문지
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• 제13권6호
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• pp.289-296
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• 2018

Drone detection in FMCW radar system needs complex techniques because a drone beat frequency is highly dynamic and unpredictable. Therefore, the current static signal processing algorithms cannot show appropriate detection accuracy. With dynamic signal fluctuation and environmental clutters, it can fail to detect a drone or make false detection. It affects to the radar system integrity and safety. Constant false alarm rate (CFAR), one of famous static signal process algorithm is effective for static environment. But for drone detection, it shows low detection accuracy. In this paper, we suggest neural network based FMCW radar system for detecting a drone. We use recurrent neural network (RNN) because it is the effective neural network for signal processing. In our FMCW radar system, one transmitter emits FMCW signal and four-way fixed receivers detect reflected drone beat frequency. The coordinate of the drone can be calculated with four receivers information by triangulation. Therefore, RNN only learns and inferences reflected drone beat frequency. It helps higher learning and detection accuracy. With several drone flight experiments, RNN shows false detection rate and detection accuracy as 21.1% and 96.4%, respectively.