• 한국철도학회:학술대회논문집
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• 한국철도학회 2008년도 추계학술대회 논문집
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• pp.93-99
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• 2008

The SeoulMerto, operating subway line No.$1{\sim}4$, was constructed in the metropolitan Seoul with the highest population. When it was built, the design was challenged to sharp curved tracks considering the protection of buildings, cultural assets, the connection to ground roads and rivers as well as to elevated railway in some parts. Lots of residential apartments and business complex have gradually increased in the area around subway stations and railway lines according to the urban development. Consequently, Requirements of better quality of life and comfortable environment caused the citizen complain for the noise. It has become one of serious social issues. In this paper, Noise level was analyzed using noise map measured in the running train of all routes. The analysis on the noise level was conducted according to railway type, track components type, seasonal type, retirement degree of the vehicle and subway station. Especially, Noise characteristics were analyzed by noise level data measured in the inside and outside of the train with geometry types of the concrete track. This study will contribute fundamental data for the "The Development of Sound-Absorbing Block on Concrete Track" promoted on The National R&D Project.

• 한국통신학회논문지
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• 제36권3A호
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• pp.296-301
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• 2011

GPS(Global Positioning System)서비스는 다 우선서비스보다 중요성을 갖는 서비스로 분류 된다. 따라서, GPS는 간섭신호로부터 보호할 필요가 있으며 이에 본 논문에서는 비트에러율(BER)을 근거로 GPS의 보호비를 제안하였다. 도출된 최대허용 간섭신호는 -190 dBm/Hz이며 간섭신호 대 잡음비(I/N)값은 -16 dB이다. 도출된 GPS 보호비(I/N)는 GPS의 실제 운용마진을 4 dB로 고려할 경우 -20 dB로 요구된다. 분석결과는 향후 안정적인 GPS 서비스 운용을 위한 국내 GPS 보호기준 제정에 도움을 줄 것으로 기대된다.

• 기술사
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• 제19권2호
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• pp.21-25
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• 1986

Structure-borne noise due to forced vibration which is originated from subway operation and transmitted to buildings in order of rail-wood tie-concrete bed-structure-soil-building foundations-members of building results in social problem of environmental pollution. Moreover this becomes a serious problem because of the increment of surface traffic and subway operation made by meeting traffic system in crowded cities. Since subway is constructed along the principal road or through the residential area and as the worst case may be, building foundations is contact with top part of subway structure, it is possible that vibration resonance results in fatal damage of buildings. And, structure-borne vibration noise due to subway operation at late and early hours have the residents suffer from insonmia, restlessness and so on. Therefore, to satisfy the future need concerning the environmental protection, this report deals with the influence of structure-borne vibration noise on the basis of the characteristics of Seoul Subway System.

• 제어로봇시스템학회논문지
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• 제21권8호
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• pp.748-752
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• 2015

We present an output feedback controller for a class of nonlinear systems with uncertain nonlinearity and sensor noise. The sensor noise has both a finite constant component and a time-varying component such that its integral function is finite. The new design and analysis method is based on the matrix inequality approach. With our proposed controller, the states and output can be ultimately bounded even though the structure of nonlinearity is more general than that in the existing results.

• 대한전자공학회논문지SD
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• 제39권8호
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• pp.42-45
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• 2002

낮은 전력선 잡음과 피드쓰루 전류를 갖는 저전력 SDRAM 출력 버퍼가 소개된다. 다수의 I/O를 갖는 SDRAM 출력 버퍼에 있어서, 제안된 언더슈트 방지 회로를 통하여, 피드쓰루 전류의 감소뿐 아니라, 전력소모의 감소가 가능하다. 효율적인 피드백 방법을 사용한 풀다운 드라이버를 사용하여, 접지선 잡음을 감소시킬 수 있다. 기존의 회로에 비하여 접지선 잡음은 66.3%, 순간 전력소모는 27.5%, 평균 전력 소모는 11.4% 감소되었다.

• 대한환경공학회지
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• 제31권12호
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• pp.1123-1128
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• 2009

치과병원에서 가동되는 기기소음이 환자들에게 피해를 줄 것으로 예상되어 치료시(스케일링, 치아제거) 및 비치료시(기기만 가동) 소음특성(소음도, 주파수 특성)을 측정하여 PSIL, NR과 같은 평가방법으로 분석하고 환자들의 기기소음에 대한 반응을 설문조사를 실시하였다. 치료기기로부터 1 m 떨어진 거리에서 측정한 소음도의 범위는 67.7~78.3 dB(A)로 4 k (Hz) 이상의 고주파성분을 나타내고 있으며 응답자의 대부분이 소음에 민감한 반응(기분이 거슬리거나, 병원방문을 망설임, 소름이 돋움, 깜짝 놀람)을 보이는 것으로 조사되었다. PSIL에 의한 소음 평가 및 설문조사 결과 환자와 치과종사자의 대화에는 문제가 없는 것으로 평가되었으나 NR곡선에 의한 평가 결과 NRN에 의한 각 실의 소음기준(ISO) 중 작업장의 소음기준(NRN 60~70 dB(A))을 훨씬 초과하는 수준이었다. 병원을 방문하는 환자들의 소음공포증을 해소시키기 위하여 방음보호구 제공, 저소음 저진동 장비의 선택, 마스킹 효과 등의 다양한 대책을 수립 제공하면 치과의료서비스 질을 개선하고 치과병원 경쟁력을 향상시킬 수 있을 것이다.

• Smart Structures and Systems
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• 제20권2호
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• pp.127-137
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• 2017

Identification of damping characteristics is of significant importance for dynamic response analysis and condition assessment of structural systems. Damping is associated with the behavior of the energy dissipation mechanism. Identification of damping ratios based on the sensitivity of dynamic responses and the model updating technique is investigated with numerical and experimental investigations. The effectiveness and performance of using the sensitivity-based model updating method and vibration monitoring data for damping ratios identification are investigated. Numerical studies on a three-dimensional truss bridge model are conducted to verify the effectiveness of the proposed approach. Measurement noise effect and the initial finite element modelling errors are considered. The results demonstrate that the damping ratio identification with the proposed approach is not sensitive to the noise effect but could be affected significantly by the modelling errors. Experimental studies on a steel planar frame structure are conducted. The robustness and performance of the proposed damping identification approach are investigated with real measured vibration data. The results demonstrate that the proposed approach has a decent and reliable performance to identify the damping ratios.

• 한국해양공학회지
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• 제26권4호
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• pp.30-36
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• 2012

Recently, the underwater radiated noises generated from large commercial ships have become a globally important issue. Countries with large ports and environmental protection organizations demand strict safety guidelines in relation to underwater radiated noise. In this paper, the coupled PFFE/PFBE method is used to investigate the vibration and underwater radiated noise of a commercial ship. PFFEM is employed to analyze the vibrational responses of the commercial ship, and PFBEM is applied to analyze the underwater radiation noise. The vibrational energy of the structure is treated as an acoustic intensity boundary condition of PFBEM to calculate the underwater radiation noise. Numerical simulations are presented for the commercial ship under various frequencies, and reliable results are obtained.

• Journal of Radiation Protection and Research
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• 제43권1호
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• pp.1-9
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• 2018

Background: In this study, we investigate the image quality of virtual monochromatic images synthesized from dual-energy computed tomography (DECT) at voltages of 80/140 kV and 100/140 kV. Materials and Methods: Virtual monochromatic images of a phantom are synthesized from DECT scans from 40 to 70 keV in steps of 1 keV under the two combinations of tube voltages. The dose allocation of dual-energy (DE) scan is 50% for both low- and high-energy tubes. The virtual monochromatic images are compared to single-energy (SE) images at the same radiation dose. In the DE images, noise is reduced using the 100/140 kV scan at the optimal monochromatic energy. Virtual monochromatic images are reconstructed from 40 to 70 keV in 1-keV increments and analyzed using two quality indexes: noise and contrast-to-noise ratio (CNR). Results and Discussion: The DE scan mode with the 100/140 kV protocol achieved a better maximum CNR compared to the 80/140 kV protocol for various materials, except for adipose and brain. Image noise is reduced with the 100/140 kV protocol. The CNR values of DE with the 100/140 kV protocol is similar to or higher than that of SE at 120 kV at the same radiation dose. Furthermore, the maximum CNR with the 100/140 kV protocol is similar to or higher than that of the SE scan at 120 kV. Conclusion: It was found that the CNR achieved with the 100/140 kV protocol was better than that with the 80/140 kV protocol at optimal monochromatic energies. Virtual monochromatic imaging using the 100/140 kV protocol could be considered for application in breast, brain, lung, liver, and bone CT in accordance with the CNR results.

• 환경영향평가
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• 제33권2호
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• pp.84-98
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• 2024

본 연구는 인천, 수원, 원주, 양산 지역에서 발파작업 동안 취득한 320개의 발파 진동 및 발파 소음 데이터를 사용하여, 발파 진동 및 발파 소음 추정에 적용가능한 예측식을 개발하였다. 발파진동 예측식은 회귀분석결과, SRSD 및 CRSD에 의한 상관계수가 각각 0.879, 0.890이며 두 경우 모두 R² ≥ 0.7로 나타났다. 발파소음 예측식은 단계적 회귀분석을 수행한 결과, 상관계수는 0.911, R² ≥ 0.7로 유의미하게 높은 상관관계를 보였다. 상수값 결정을 위한 추가 회귀분석 결과 상관계수는 0.881, R² ≥ 0.7로 나타났다. 상기의 결과, 개발된 예측식이 다른 도시지역의 재건축사업이나 공동주택 건설에 따른 환경영향평가나 교육환경평가의 소음·진동분야 보고서 작성 시 정합성이 높은 발파소음·진동 예측값을 도출할 수 있을것으로 기대한다.