• Journal of Audiology & Otology
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• 제25권1호
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• pp.14-21
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• 2021

Background and Objectives: There is growing interest in the use of the Level-specific (LS) CE-Chirp^® stimulus in auditory brainstem response (ABR) due to its ability to produce prominent ABR waves with robust amplitudes. There are no known studies that investigate the test-retest reliability of the ABR to the LS CE-Chirp^® stimulus. The present study aims to investigate the test-retest reliability of the ABR to the LS CE-Chirp^® stimulus and compare its reliability with the ABR to standard click stimulus at multiple intensity levels in normal-hearing adults. Subjects and Methods: Eleven normal-hearing adults participated. The ABR test was repeated twice in the same clinical session and conducted again in another session. The ABR was acquired using both the click and LS CE-Chirp^® stimuli at 4 presentation levels (80, 60, 40, and 20 dBnHL). Only the right ear was tested using the ipsilateral electrode montage. The reliability of the ABR findings (amplitudes and latencies) to the click and LS CE-Chirp^® stimuli within the same clinical session and between the two clinical sessions was calculated using an intra-class correlation coefficient analysis (ICC). Results: The results showed a significant correlation of the ABR findings (amplitude and latencies) to both stimuli within the same session and between the clinical sessions. The ICC values ranged from moderate to excellent. Conclusions: The ABR results from both the LS CE-Chirp^® and click stimuli were consistent and reliable over the two clinical sessions suggesting that both stimuli can be used for neurological diagnoses with the same reliability.

• 대한청각학회지
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• 제25권1호
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• pp.14-21
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• 2021

Background and Objectives: There is growing interest in the use of the Level-specific (LS) CE-Chirp^® stimulus in auditory brainstem response (ABR) due to its ability to produce prominent ABR waves with robust amplitudes. There are no known studies that investigate the test-retest reliability of the ABR to the LS CE-Chirp^® stimulus. The present study aims to investigate the test-retest reliability of the ABR to the LS CE-Chirp^® stimulus and compare its reliability with the ABR to standard click stimulus at multiple intensity levels in normal-hearing adults. Subjects and Methods: Eleven normal-hearing adults participated. The ABR test was repeated twice in the same clinical session and conducted again in another session. The ABR was acquired using both the click and LS CE-Chirp^® stimuli at 4 presentation levels (80, 60, 40, and 20 dBnHL). Only the right ear was tested using the ipsilateral electrode montage. The reliability of the ABR findings (amplitudes and latencies) to the click and LS CE-Chirp^® stimuli within the same clinical session and between the two clinical sessions was calculated using an intra-class correlation coefficient analysis (ICC). Results: The results showed a significant correlation of the ABR findings (amplitude and latencies) to both stimuli within the same session and between the clinical sessions. The ICC values ranged from moderate to excellent. Conclusions: The ABR results from both the LS CE-Chirp^® and click stimuli were consistent and reliable over the two clinical sessions suggesting that both stimuli can be used for neurological diagnoses with the same reliability.

• Journal of Ecology and Environment
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• 제33권4호
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• pp.307-315
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• 2010

Males of the field cricket Teleogryllus emma produce calling songs that are attractive to receptive females. The calling songs of T. emma consist of two components, the long chirp that is composed of up to 12 single pulses, followed by a variable number of short chirps. Based on the analysis of coefficient of variation (CV), temporal characters of the long chirp were less variable than those of the short chirps in male calling songs. To test for phonotactic selectivity of females, we conducted a single-stimulus playback experiment in which five stimuli (standard, long chirp only, long chirp augmented, short chirps only, and short chirps augmented) were used. The standard stimulus included both long and short chirps whose characteristics were derived from the calling songs of field populations. Results of the playback experiment showed that female crickets oriented more frequently toward the stimuli that included the long chirp (standard, long chirp only, and long chirp augmented stimuli) than toward the stimuli lacking the long chirp (short chirps only and short chirps augmented stimuli), indicating that the long chirp in the calling songs was required to elicit positive phonotaxis in the female crickets. The result of CV analysis of the male calling songs and the findings of the female phonotaxis experiment suggested that the long chirp of calling songs may play a role in species recognition in T. emma.

• 비파괴검사학회지
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• 제31권2호
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• pp.118-126
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• 2011

초음파가진 열화상시험 중 가진 방법이 시편에 가진된 진동의 시스템 응답 특성에 미치는 영향에 대하여 연구하였다. 복잡한 현상을 가진 터빈 블레이드 시편에 가진된 진동의 특성을 분석하기 위하여 고출력 가진이 가능한 초음파 혼이 사용되었다. 초음파 혼에 입력되는 신호의 특성이 가진된 진동의 특성에 미치는 영향에 대하여 연구하였고 블레이드를 클램프에 고정한 후 가진기와 클램프를 연결하는 방법이 진동신호에 미치는 영향에 대해서도 연구하였다. 연구 결과를 통하여 첩(chirp) 입력선호와 볼트를 사용하여 클램프와 혼을 연결하는 방법을 가진 방법으로 제안하였다. 이러한 가진 방법은 다양한 종류의 터빈 블레이드 뿐만 아니라 다른 기계부품들의 시험에 적용될 수 있다.

• 한국위성정보통신학회논문지
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• 제8권2호
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• pp.88-93
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• 2013

지구 관측 영상을 획득하는 합성개구레이더의 해상도를 향상시키기 위해서는 광대역 첩신호 발생이 필수적으로 요구된다. 본 논문에서는 고해상도를 얻기 위한 저궤도 관측위성용 합성개구레이더의 광대역 신호 발생기를 설계하고 시험 모델 제작 및 기능 시험결과를 다루었다. 구현된 광대역 신호 발생기의 파형발생기는 위성에서 주로 적용되는 메모리맵 기반의 구조를 사용하였으며 내부는 파형 발생을 위한 디지털 모듈과 직교 변조를 위한 RF 모듈로 구성된다. 디지털 모듈의 메모리에 저장된 I/Q 신호는 D/A 변환기를 거쳐 RF 모듈로 전달되며 1275 MHz 기준 신호에 대해 직교 변조기를 거쳐 변조된다. 광대역 신호 발생기 검증을 위한 치구 및 GUI도 개발하였다. 시험 결과 대역폭 요구사항 144 MHz를 잘 만족하고 있음을 확인하였다. 또한 사전 왜곡 보상 기능을 구현하여 발생된 왜곡이 보상됨을 확인하였다.

• Journal of Audiology & Otology
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• 제25권4호
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• pp.199-208
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• 2021

Background and Objectives: No known studies have investigated the influence of stimulus polarity on the Auditory Brainstem Response (ABR) elicited from level-specific (LS) chirp. This study is important as it provides a better understanding of the stimulus polarity selection for ABR elicited from LS chirp stimulus. We explored the influence of stimulus polarity on the ABR from LS chirp compared to the ABR from click at 80 dBnHL in normal-hearing adults. Subjects and Methods: Nineteen adults with normal hearing participated. The ABRs were acquired using click and LS chirp stimuli using three stimulus polarities (rarefaction, condensation, and alternating) at 80 dBnHL. The ABRs were tested only on the right ear at a stimulus rate of 33.33 Hz. The ABR test was stopped when the recording reached the residual noise level of 0.04 μV. The ABRs amplitudes, absolute latencies, inter-peak latencies (IPLs), and the recorded number of averages were statistically compared among ABRs at different stimulus polarities and stimuli combinations. Results: Rarefaction polarity had the largest ABR amplitudes and SNRs compared with other stimulus polarities in both stimuli. There were marginal differences in the absolute latencies and IPLs among stimulus polarities. No significant difference in the number of averages required to reach the stopping criteria was found. Conclusions: Stimulus polarities have a significant influence on the ABR to LS chirp. Rarefaction polarity is recommended for clinical use because of its larger ABR peak I, III, and V amplitudes than those of the other stimulus polarities.

• 대한청각학회지
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• 제25권4호
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• pp.199-208
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• 2021

Background and Objectives: No known studies have investigated the influence of stimulus polarity on the Auditory Brainstem Response (ABR) elicited from level-specific (LS) chirp. This study is important as it provides a better understanding of the stimulus polarity selection for ABR elicited from LS chirp stimulus. We explored the influence of stimulus polarity on the ABR from LS chirp compared to the ABR from click at 80 dBnHL in normal-hearing adults. Subjects and Methods: Nineteen adults with normal hearing participated. The ABRs were acquired using click and LS chirp stimuli using three stimulus polarities (rarefaction, condensation, and alternating) at 80 dBnHL. The ABRs were tested only on the right ear at a stimulus rate of 33.33 Hz. The ABR test was stopped when the recording reached the residual noise level of 0.04 μV. The ABRs amplitudes, absolute latencies, inter-peak latencies (IPLs), and the recorded number of averages were statistically compared among ABRs at different stimulus polarities and stimuli combinations. Results: Rarefaction polarity had the largest ABR amplitudes and SNRs compared with other stimulus polarities in both stimuli. There were marginal differences in the absolute latencies and IPLs among stimulus polarities. No significant difference in the number of averages required to reach the stopping criteria was found. Conclusions: Stimulus polarities have a significant influence on the ABR to LS chirp. Rarefaction polarity is recommended for clinical use because of its larger ABR peak I, III, and V amplitudes than those of the other stimulus polarities.

• 한국전자파학회논문지
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• 제21권3호
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• pp.321-330
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• 2010

본 논문에서는 컴프레시브 RFID 신호를 탐지하기 위한 컴프레시브 수신기의 이론적 배경과 구체적 구현 방법, 그리고 분산 지연선과 chirp LO의 설계 방안에 대해 기술하였다. 컴프레시브 수신기의 주요 구성품 중 하나인 분산 지연선을 대역폭 6 MHz, 분산 지연 시간 $13{\mu}s$으로 설계하여 $LiNbO_3$ 재질 기반의 SAW(Surface Acoustic Wave) 기술을 통해 구현하였고, DDS(Direct Digital Synthesizer)를 이용하여 chirp LO를 구현하였다. 또한 RFID 리더에 내장되어 연동될 수 있도록 컴프레시브 수신기를 구성하였다. 시험 결과, 단일 신호 입력시 주파수 오차는 최대 25 kHz, 수신 감도는 -44 dBm, 500 kHz 간격으로 동시에 입력되는 6개의 신호에 대한 주파수 오차는 최대 75 kHz로서 제작된 컴프레시브 수신기가 밀집된 RFID 운영 환경에 적합함을 보였다.

• 항공우주기술
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• 제9권2호
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• pp.105-115
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• 2010

본 논문에서는 소형항공기의 종축 및 횡방향축 동안정성 비행시험을 수행하고 그 결과를 분석 정리하였다. 대상 항공기는 한국항공우주연구원에서 개발한 4인승 선미익형 항공기인 반디 실용화 1호기이며, 탑재 센서 및 실시간 텔레메트리시스템을 통해 비행시험 데이터를 확보하였다. 대상 항공기의 동안정성 비행시험은 대상 항공기 운동모델의 공력 미계수를 추정하여 고유주파수 및 댐핑 등의 비행성을 판별하여 동안정성을 분석할 목적으로 수행되며, 본 비행시험에서는 chirp, 3211 및 doublet 조종입력을 사용하여 비행데이터를 확보한 후 최대공산 추정기법 (MMLE)을 적용하여 공력 미계수를 추정하였다.

• 한국전자파학회논문지
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• 제27권11호
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• pp.949-958
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• 2016

본 논문은 다중대역 및 다중모드의 레이다 기능을 갖는 새로운 SDR(Software Defined Radar) 플랫폼의 개발 결과를 제시한다. SDR 하드웨어 플랫폼은 다중대역의 S, X, 그리고 K 밴드의 교체 가능한 RF 송수신기 및 안테나 모듈과 프로그램 가능한 신호처리기 모듈로 구현된다. 소프트웨어 플랫폼은 다중모드의 CW, Pulse, FMCW, LFM Chirp 파형 발생과 적응 가능한 신호처리 알고리즘 라이브러리 모듈 및 개방형 API 소프트웨어 모듈로 구현된다. SDR 플랫폼의 레이다 통합시험을 통하여 동작 성능을 실시간으로 검증하였으며, 또한 현장 활용시험을 통하여 지상 표적 및 비행체 드론 표적을 성공적으로 탐지하여 시험 결과를 제시하였다.