• 한국도로학회논문집
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• 제15권6호
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• pp.33-39
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• 2013

PURPOSES : This research investigates traffic noise characteristics as change the transverse rumble strips shape from rectangular to cylinder at toll plaza of highway. METHODS : The traffic noise was investigated at two different places at toll plaza of highway. One is modified grooving, another is employed cylinder shape of TRS instead of rectangular shape of TRS. A measurement of traffic noise was conducted at same location and time period. The traffic volume information was gotten from office of highway office and vehicle speed was measured by speed measuring device. The traffic noise measurement was conducted from 13:00 to 23:00 and by pass-by method. Also, the traffic noise was measured behind noise barrier. Various distance from noise barrier(7.5m, 30m, 50m) and different heights(1.2m, 3m, and 5m) were parameter for measurement of traffic noise in this study. RESULTS : The class 1 vehicle was contributed from traffic volume which was increased 1,500. However, the distribution of traffic speed didn't change compare to previous investigated period. From this study, It was found that the external traffic noise was changed as function of geometric shape of TRS. The external noise from modified grooving was less than 1.2dB(A) of the current TRS. A difference of traffic noise was 20dB(A) before and after barrier. It came from a noise barrier effect as reduction of traffic noise. According to investigate a traffic noise distribution near barrier, there is similar noise characteristic as function of height at 7.5m distance from noise barrier. Also, There is no different traffic noise between 30m and 50m from source of the noise of sound barrier. CONCLUSIONS : Based on this traffic noise investigation result, there is a clear characteristic difference as changed TRS shape. The traffic noise was reduced by changed TRS shape. Specially, traffic noise was decreased although the traffic volume was increase for same investigation time and period. It is implied that cylinder type of TRS significantly reduces the traffic noise. The specification of various TRS will be studied in the future.

• 한국전자통신학회논문지
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• 제12권5호
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• pp.899-906
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• 2017

본 논문은 다세대 공동 주택에서 윗층과 아래층 간에 발생하는 층간 소음을 줄일 수 있도록 도와주는 층간소음 방지 시스템을 제안하고 있다. 제안하는 시스템에서는 오픈소스 컨트롤러 중 하나인 아두이노 보드에 소리 감지 센서와 진동 감지 센서를 연결하여 층간 소음으로 판단하는 소리와 진동을 입력 받고 이를 고속 푸리에 변환을 이용하여 주파수 대역에서의 신호 분석을 수행한다. 특정 주파수 대역의 신호 크기가 구조물의 투과 손실을 고려한 기준을 넘을 때에는 LCD화면에 경고 메시지를 보내고 휴대폰으로 이메일 또는 메시지를 전송하도록 하였다. 이를 통해 시스템은 사용자가 소음 발생 상황을 인지하여 스스로 주의할 수 있도록 돕는다. 시스템 검증을 위한 실험에서 제안하는 시스템은 외부 입력 신호에서 130 Hz~1040 Hz의 대역 성분 추출을 수행하였으며, 추출된 신호의 크기와 투과 손실의 차이 값이 45 dB를 초과할 경우 기기의 연결된 디스플레이와 Wi-Fi로 연결된 모바일 기기에 현재 소음이 발생하고 있음을 공지하는 동작을 수행하였다.

• 치위생과학회지
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• 제23권2호
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• pp.176-184
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• 2023

Background: Recently, a piezoelectric ultrasonic scaler based on a feedback control mechanism was introduced for pain relief. This study aimed to investigate the effects of a new ultrasonic scaler in reducing pain and discomfort in adults. Methods: A newly introduced ultrasonic scaler (Master 700^®) was used as the test device and a conventional ultrasonic scaler device (PIEZON^®) was used as the control device. Forty-one healthy adults visited the dental clinic for dental scaling but did not undergo scaling or periodontal treatment within 6 months. Intraoral examinations were performed before scaling and 3 months later; before scaling, both devices were randomly assigned on the left or right side of each dentition (split-mouth model) and scaling was performed by a registered dental hygienist. The levels of pain and discomfort during scaling were evaluated subjectively and objectively using the visual analog scale (VAS) and physiological monitoring of the heart rate (HR), respectively. Time was measured for each device. Results: All clinical indicators, except bleeding on probing, significantly improved with both devices. The treatment times were 7 minutes, 13 minutes (control) and 6 minutes, 59 minutes (test). VAS scores for pain were 4.89±2.12 (control) and 4.58±2.77 (test) points out of 10; for noise, these were 4.68±2.33 (control) and 4.55±2.55 (test), and for vibration, the values were 4.26±2.0 (control) and 4.18±2.48 (test). HR averages were 72.34±3.39 (control) and 75.97±9.78 (test) beats/min. No statistically significant differences were observed between the devices. Conclusion:The pain, discomfort levels, and scaling time of the new piezoelectric ultrasonic scaler did not differ from those of the conventional device. Further research and development are necessary for more prominent pain-relief effects of scaling devices.

• 한국산학기술학회논문지
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• 제12권5호
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• pp.2011-2018
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• 2011

본 논문에서는 공조용 로타리 컴프레서에서 발생하는 소음을 줄이기 위하여 음향 홀로그래피를 이용하는 방법을 다룬다. 소음이 방사되는 것을 음향 홀로그래피를 이용하여 정상적인 컴프레서와 문제가 있는 컴프레서에 대하여 측정하였다. 음향 홀로그램은 2가지 컴프레서의 다수의 격자점에서 측정 및 예측하였고, 컴프레서 표면 위로 재구성하였다. 2개의 마이크로폰을 사용하여 1344개의 측정 점에서 측정을 수행하였고, 그 중 1개의 마이크로폰은 스캐닝용이고 또 다른 하나의 마이크로폰은 레퍼런스용이다. 음향 홀로그래피는 소음원을 그래픽적으로 보여주기 위한 좋은 도구이다. 본 논문에서 컴프레서의 표면에서 소음 원 위치를 정확히 찾을 수 있었고, 그 소음원은 소음을 발생시키는 부품과 관계된 것이었다. 음향 홀로그래피는 가전제품에 대해 소음 저감 방법으로서 유용함을 알 수 있다.

• 정보보호학회논문지
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• 제29권3호
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• pp.491-501
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• 2019

최근 보안 디바이스의 물리적 취약성을 찾을 수 있는 부채널 분석 분야에서 딥러닝을 활용한 연구가 활발히 진행되고 있다. 하지만, 최신 딥러닝 기반 부채널 분석 기술 연구는 템플릿 공격 등과 같은 프로파일링 기반 부채널 분석 환경에서 파형을 옳게 분류하기 위한 연구에 집중되어 있다. 본 논문에서는 이전 연구들과 다르게 딥러닝을 신호 전처리 기법으로 활용하여 차분 전력 분석, 상관 전력 분석 등과 같은 논프로파일링 기반 부채널 분석의 성능을 고도화할 수 있는 방법을 제안한다. 제안기법은 오토인코더를 부채널 분석 환경에 적합하게 변경하여 부채널 정보의 노이즈를 제거하는 전처리 기법으로, 기존 노이즈 제거 오토인코더는 임의로 추가한 노이즈에 대한 학습을 하였다면 제안하는 기법은 노이즈가 제거된 라벨을 사용하여 실제 데이터의 노이즈를 학습한다. 제안기법은 논프로파일링 환경에서 수행 가능한 전처리 기법이며 하나의 뉴런 네트워크의 학습만을 통해 수행할 수 있다. 본 논문에서는 실험을 통해 제안기법의 노이즈 제거 성능을 입증하였으며, 주성분분석 및 선형판별분석과 같은 기존 전처리 기법들과 비교하여 우수하다는 것을 보인다.

• ETRI Journal
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• 제38권1호
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• pp.112-122
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• 2016

This paper presents a set of candidate regulatory requirements for TV band devices (TVBDs) in the Rep. of Korea. To guarantee the protection of incumbent services, especially digital TV (DTV) and wireless microphones, in TV frequency bands, we suggest minimum separation distances of TVBDs from the noise-limited contour according to incumbent users and TVBD types. This paper also deals with multiple sets of separation distances of a co-channel TVBD network from a DTV protected contour on the basis of the radio propagation characteristics of different geographic areas to make good use of TV white space (TVWS) and safely protect the DTV service. We present a low-power transmission mode of TVBDs and the relevant separation distances for small-cell deployment. The service coverage reduction ratio of a TVBD network is investigated in the presence of DTV interference in four geographic areas. The TVWS field verification results, conducted on the island of Jeju (Rep. of Korea), show that incumbent services operate well without harmful interference from neighboring TVBDs with the proposed separation distances.

• 한국전기전자재료학회논문지
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• 제20권6호
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• pp.491-495
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• 2007

This paper has demonstrated the electrical properties of SiGe pMOSFETs fabricated on both bulk-Si and PD SOI substrates. Two principal merits, the mobility increase in strained-SiGe channel and the parasitic capacitance reduction of SOI isolation, resulted in improvements in device performance. It was observed that the SiGe PD SOI could alleviate the floating body effect, and consequently DIBL was as low as 10 mV/V. The cut-off frequency of device fabricated on PD SOI substrate was roughly doubled in comparison with SiGe bulk: from 6.7 GHz to 11.3 GHz. These experimental result suggests that the SiGe PD SOI pMOSFET is a promising option to drive CMOS to enhance performance with its increased operation frequency for high speed and low noise applications.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제13권9호
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• pp.4518-4540
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• 2019

With the development of IT convergence technology, autonomous driving has gradually developed; however, the vehicle is still operated by the driver, who should always be in good health - but sometimes, this is not the case. It is especially dangerous to drive when drowsy, and unable to fully concentrate on driving, such as when taking certain medicines, or through fatigue. Drowsy driving is at least eight times more dangerous than normal driving, and as dangerous as drunk driving. Previous research has looked at technology to detect drowsiness, in order to wake up drivers when necessary, or to safely stop the vehicle. Furthermore, many studies have been conducted to find out when drowsiness occurs. However, it is more desirable for the driver to take sufficient rest during a break, in order to be able to continue to focus and drive. In other words, it is important to maintain a normal state before drowsiness. In this study, we introduce a sound source to increase driver concentration and prevent drowsiness, another that can improve the quality of sleep, and a system that produces these sound sources. The proposed system has a noise reduction effect of about 15 dB. We have confirmed that the proposed sound induces an EEG of the desired form.

• 한국기계가공학회지
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• 제17권4호
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• pp.113-122
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• 2018

A hydraulic breaker is an attachment of an excavator, and it crushes stones. Recently, research to reduce the impact and noise of breakers are ongoing. In this paper, a method to improve the upper, lower, and side dampers, which act as insulation for the attenuation of vibration during breaker operation, is studied through testing and simulation. To obtain the nonlinear material constants required for the simulation, the biaxial tensile test was performed with urethane, which is a material used for dampers. The existing parts and the improved parts were compared and evaluated using the LS-DYNA program. As a result, 50% of the equivalent stress was reduced in the bracket body of the hydraulic breaker, and the equivalent stress of the side damper was also decreased. We verified that the fatigue conditions were satisfied by performing a fatigue analysis.

• 대한의용생체공학회:의공학회지
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• 제18권4호
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• pp.421-428
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• 1997

초전도양자간섭소자(SQUID)를 이용한 자장센서는 현재 개발된 자장센서중에서 감도가 가장 우수한 소자로서 인체의 두뇌에서 발생하는 매우 미약한 자장에 측정이 가능하다. 뇌자도측정은 현재 많이 사용되고 있는 전기적인 측정(뇌파, 뇌유발전위) 에 비해 공간분해능이 우수하고, fMRI나 PET에 비해서는 시간분해능이 우수하므로 뇌기능연구에 유용하게 사용될 수 있다. 본 연구에서는 뇌자도 측정을 위하여 4-채널 SQUID시스템을 개발하였다. 개발된 시스템의 주요 특징은 새로운 방식의 SQUID센서를 채택함으로서 간단한 회로로써 SQUID구동이 가능하도록 하였으며, 검출코일의 신뢰성을 향상시키기 위하여 집적화된 평면형 코일을 사용하였다. 외부 환경잡음을 소거하기 위하여 자기차폐실을 설치하였고, 개발된 SQUID 시스템을 이용하여 뇌의 청각령으로부터 발생하는 자기신호를 측정하였다.