• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2001년도 봄 학술발표회 논문집
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• pp.789-794
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• 2001

The acoustic emission(AE) signal from concrete cylinder specimen during failure process under cycling compressive loads were recorded and analyzed. Different filters were set on the AE signal duration based on the characteristic of amplitude distribution. From the value of AE signal amplitude, which corresponds to the occurrence of the peak for AE hits, the AE signals from concrete compressive specimen were divided into five sections. The relationship between the AE signal section and the failure mechanism of these materials, analyzed on the meso-structure level was determined. Based on the experiments, the AE characteristics of each failure mechanism are given. The results show that the AE technique is a valuable tool to study the failure mechanism of concrete.

• 조명전기설비학회논문지
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• 제29권3호
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• pp.102-106
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• 2015

In order to avoid the electrical fire, AFCI(Arc Fault Cirruit Interrupter) has been obligated to be adopted in the United States of America since 2002. A study was carried out on how to detect Arc. In this paper, The propose is high-frequency signal detection methods and RSSI(Received Signal Strength Indication) signal processing algorithm for Arc detection. and the electrical characteristics were verifying.

• 대한의용생체공학회:의공학회지
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• 제28권1호
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• pp.24-28
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• 2007

Presuming that firing neurons have motions inside the MRI magnet due to the interaction between the neuronal magnetic field and the main magnetic field, we applied motion encoding gradients to dissected snail ganglia to observe faster responding MRI signal than the BOLD signal. To activate the snail ganglia in synchronization with the MRI pulse sequence, we used electrical stimulation with the frequency of 30 Hz and the pulse width of 2s. To observe the fast responding signal, we used the volume selected MRI sequence. The magnetic resonance signal intensity, measured with 8 ms long motion encoding gradient with a 20mT/m gradient strength, decreased about $3.46{\pm}1.48%$ when the ganglia were activated by the electrical stimulation.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 하계학술대회 논문집 Vol.3 No.2
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• pp.699-702
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• 2002

A DC current sensor is disclosed in which two pairs of saturable cores are provided so as enclose a conductor carrying a direct current to be measured. On each of the saturable cores, a bias winding, a feedback winding and an output winding are wound. Circuit for detection of an asymmetry in the magnetization current, generated by a reference alternating voltage, in a signal-conditioner. The reference alternating voltage is fed to the respective series circuits such that no resultant induction current is induced in the modulating current. The voltages over the resistor form input signals for two peak value detectors, the strength of the output signal of which represents the degree of asymmetry of magnetization current. This paper describes the development a DC current sensor and its signal-conditioner.

• 한국식품영양과학회지
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• 제30권1호
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• pp.43-47
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• 2001

Electron spin resonance (ESR) spectroscopy was used to investigate the effect of irradiation dose on the ESR signal intensity and to identify the stability of radicals after 9 weeks of storage in order to detect irradiated shellfishes. The irradiated shellfishes (short-necked clam, purplish washington clam, freshwater clam, jackknifed clam, scallop and hard-shell mussel) presented an asymmetric absorption in shape at $g_{1}$=2.002~2.003 and $g_{2}$=1.998. The strength of the ESR signal increased linearly with the applied doses (1~7 kGy). A highly positive correlation coefficients ($R^{2}$=0.9136~0.9896) were obtained between the irradiation dose and corresponding ESR signal intensity. The intensity of the signals after irradiation was stable even after 9 weeks of storage at 5$\pm$1$^{\circ}C$.

• 한국식품영양과학회지
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• 제30권2호
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• pp.239-242
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• 2001

Electron spin resonance(ESR) spectroscopy was used to investigate the effect of irradiation dose on the ESR signal intensity of irradiated spices and to identify the stability of radicals after storage. Red, white and black peppers, and garlic powders were irradiated with doses of 0, 1, 5, 10, 20 and 30 kGy at room temperature using a Co-60 irradiator. Triplet ESR signals were observed in irradiated pepper powders, while singlet ESR signals were observed in irradiated garlic powders. Those characteristic signals were not detected in non-irradiated samples. The strength of ESR signals linearly increased with the applied doses(1~3 kGy). Highly positive correlation coefficients ($R^2$=0.9757~0.9933) were obtained between the irradiation doses and the corresponding ESR signal intensities. The signal intensities of irradiated samples were stable even after 97 days of storage at room temperature.

• 제어로봇시스템학회논문지
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• 제16권7호
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• pp.720-725
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• 2010

In AGPS method, user position can be obtained even in the shadow region by improving signal sensitivity. A hybrid long integration scheme employing both coherent and non-coherent integration method is commonly used in AGPS receivers. Because coherent loss increases as residual frequency become large, residual frequency should be minimized to maximize coherent integration gain. This paper presents performance analysis of residual frequency estimator using FFT in fine-time assistance AGPS method. Considering the hardware complexity and the estimation accuracy, optimal length of FFT is proposed for GPS L1 C/A signal. Signal sensitivity for estimating the residual frequency is also analysed. By field experimental results, it is found that the residual frequency can be successfully estimated using 1 second snap-shot data when GPS signal strength is larger than -150 dBm and its RMS error is 3Hz.

• Journal of Positioning, Navigation, and Timing
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• 제8권1호
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• pp.13-18
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• 2019

This paper analyzes the signal acquisition performance of the legacy GNSS spreading codes and a polyphase code. The code length and chip rate of a polyphase code are assumed to be same as those of the GPS L1 C/A and Galileo E1C codes. The autocorrelation and cross correlation characteristics are analyzed. In addition, a way to calculate a more accurate probability of false alarm for a code with sidelobe non-zero auto-correlation function is proposed. Finally, we estimate the probability of detection and the mean acquisition time for a given signal strength and the probability of false alarm.

• 한국통신학회논문지
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• 제38C권11호
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• pp.1044-1050
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• 2013

본 논문은 ETRI에서 개발한 GPS RF 신호생성기와 상용수신기인 U-Blox 수신기를 이용하여 기만신호의 공격을 완화하는 방법에 대하여 분석하였다. 기만신호는 대상 수신기의 코드 및 반송파 성분의 변이를 이용하여 대상수신기가 비정상적인 위치를 생성하도록 하는 것이다. 우리는 이러한 기만신호 공격에 따른 수신기에서의 신호세기 및 항법해 영향을 분석하였다. 또한 기만신호를 제거하기 위하여 기만신호와 역위상 코드를 가지는 신호를 고려하였다. GPS RF 신호생성기를 이용하여 정상적인 GPS 신호, 기만신호, 기만신호와 역위상을 가지는 항기만신호를 생성하였고 기만신호와 항기만신호간의 코드 위상차이에 따른 기만신호 공격의 영향을 수신기를 통하여 확인하였다. 기만 신호의 코드 지연과 동일한 코드지연의 신호를 생성할 경우 기만신호가 상쇄되는 것을 확인하였다.

• 한국음향학회지
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• 제28권4호
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• pp.328-335
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• 2009

음향수신신호의 위상은 매질에 대한 정보를 포함하고 있기 때문에 위상 변동을 연구하는 것은 매질에 대한 연구와 동반 되어야 한다. 또한 SAS (Synthetic Aperture Sonar)나 수중통신 등의 신호처리 시 수신신호의 위상변동 보정이 필요하다. 본 연구에서는 미세구조 난류에 의한 수신신호의 위상분산을 고찰하였다. 국지적으로 등방성이고 균질한 난류 환경 하에서 난류세기인자를 구하였고 음파 전달경로에 따라 난류세기가 미치는 영향을 고려하여 위상분산을 계산하였다. 난류세기 계산에 필요한 CTD자료와 ADCP자료는 묵호항 근처에 설치된 부표에서 획득하였으며 음파 전달경로는 Bellhop알고리즘을 이용한 음선 모델을 사용하였다. 결과적으로 난류세기인자는 주로 수온과 유속의 변화에 의해 결정되었으며 수신신호의 위상분산에 영향을 주었다. 이러한 위상분산은 소나 운용에 고려되어야 할 사항으로 여겨진다.