• 한국철도학회:학술대회논문집
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• 한국철도학회 2006년도 추계학술대회 논문집
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• pp.305-309
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• 2006

In this paper vibration reduction characteristics of floating floors used in railway vehicles are studied. Vibration reduction characteristics are compared through a series of tests for elastically-coupled floor and rigidly-coupled floor. It was found that elastically-coupled floor has larger vibration reduction amount than rigidly-coupled floor. Around the fundamental natural frequency, however, elastic floor has poor vibration reduction effect than rigid floor. Measures to reduce structure-borne noise are also discussed based on the test results. Structure-borne noise for running railway vehicles cannot be reduced by an effort to deviate resonance between natural frequency of floors and major exciting forces. Instead, reducing vibration level of top floor and using covers which have low sound radiation coefficient will be effective for reducing structure-borne noise.

• Safety and Health at Work
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• 제2권4호
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• pp.336-347
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• 2011

Objectives: In Korea, an average of 258 workers claim compensation for their noise-induced hearing loss (NIHL) on an annual basis. Indeed, hearing disorder ranks first in the number of diagnoses made by occupational medical check-ups. Against this backdrop, this study analyzed the impact of 19 types of noise-generating machines and equipment on the sound pressure levels in workplaces and NIHL occurrence based on a 2009 national survey on work environments. Methods: Through this analysis, a series of statistical models were built to determine posterior probabilities for each worksite with an aim to present risk ratings for noise levels at work. Results: It was found that air compressors and grinding machines came in first and second, respectively in the number of installed noise-generating machines and equipment. However, there was no direct relationship between workplace noise and NIHL among workers since noise-control equipment and protective gear had been in place. By building a logistic regression model and neural network, statistical models were set to identify the influence of the noise-generating machines and equipment on workplace noise levels and NIHL occurrence. Conclusion: This study offered NIHL prevention measures which are fit for the worksites in each risk grade.

• 한국컴퓨터정보학회논문지
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• 제27권5호
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• pp.181-188
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• 2022

본 연구는 치과병원에서 진료 시 발생하는 소음특성을 NR-곡선, PSIL에 적용하여 소음수준 및 적절한 대화거리를 산정한 결과를 제시하고자 실시하였다. 치과병원에서 치료 시 소음특성을 분석한 결과 소음에 의한 건강 보존한계 값인 60dB(A)을 초과하고 고주파 성분의 소음도가 높은 것으로 분석되었다. NR곡선에 적용하여 평가한 결과 일부 치료 시 작업장 소음기준을 초과하고 근무자와 환자 사이에 이루어지는 대화에 대한 회화방해도 수준을 분석한 결과 보통크기의 소리일 경우 0.13m~0.42m, 큰 소리일 경우 0.26m~0.85m 정도 인 것으로 분석되어 환자와 근무자 간의 정확한 의사전달을 위하여 가급적 1m 이내의 거리에서 대화가 이루어지는 것이 바람직 할 것으로 판단된다. 병원의 의료서비스 질의 향상을 도모하고 치과공포를 감소시키기 위하여 근무자에게 방음보호구를 지급하고 소음 발생원(진료 시 사용되는 치료기기) 및 수음원(환자 및 근무자)에 대한 방음대책도 필요 할 것으로 판단된다.

• 한국환경보건학회지
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• 제25권3호
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• pp.94-102
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• 1999

To estimate the effects of environmental noise on inhabitants' life in an apartment area at Taejon, noise levels and traffic volume of major roads were measured. 203 housewives were surveyed by questionaires including general factors, noise related factors and three items of life effects: subjective evaluations on the general environment, annoyance, and life disturbance due to environmental noise. At the boundary adjacent to the road with more traffic volume, noise level was higher; according to the time, the amount of noise level was in the morning, in the evening, at noon, and at night in order. Most of boundary noise levels were higher than those of recommended standard environmental noise levels in a residential area. The boundary noise level showed a very significant linear relationship with traffic volume of near roads. Noise level difference in the apartments adjacent to three roads was ranged 2.4~6.7dB between in windows open and close state. The apartments adjacent to 9 lane or 6 lane-road, which were protected by noise prevention wall and 20m or more distance from the roads, showed higher noise level at middle floors and high floors than those of low floors; but the buildings adjacent to 4 lane-road, with no protection, showed higher noise level at low and middle floors than those of high floors. Among 203 housewives, 120(59.1%) participated in this study, and 86(73.2%) of them answered that the most serious environmental noise was traffic noise from near roads. Comparing traffic noise levels with those of before-migration, 67.0% participants found the environmental noise became louder. Fifty eight(49.5%) of the participants wanted noise protection wall and 15(25.9%) of them were willing to charge the fee. Less perception on the present noise comparing to those before-migration, less traffic volume, and lower noise levels in the apartments were related to higher scores of self-evaluation on the environment. Higher susceptibility on the present noise, areas with more traffic volume, higher boundary noise levels, and higher noise levels showed higher scores of annoyance on environmental noise and life disturbance. Considering above all things, it was suggested that traffic noise in this area was the major problem of environmental noise, and its' effect was so serious that inhabitants needed some preventive measures for better life quality.

• 응용통계연구
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• 제21권2호
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• pp.233-245
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• 2008

본 논문은 영상을 획득할 때 잡음센서나 통신채널 불량으로 흔히 생기는 임펄스 잡음을 효율적으로 제거하는 방법에 대해 논의 하고자 한다. 제안된 방법은 잡음 픽셀 검출과 추정이라는 두 단계에 의해 이루어진다. 임펄스 잡음 검출기를 통하여 영상 전체에 걸쳐 잡음 픽셀여부를 검출한 후 잡음 픽셀로 판정되면 주변의 잡음 픽셀 개수에 따라 적응력 있게 $3{\times}3$ 윈도우의 가중평균 혹은 $5{\times}5$ 윈도우의 가중평균을 사용하여 추정한다. 제안된 방법의 성능을 평가하기 위해 영상실험을 통하여 기존의 잡음 제거 방법들과 정성적인 비교, PSNR과 MAE를 통한 정량적인 비교 그리고 수행 시간을 측정한 결과 제안된 방법은 잡음 제거는 물론 원영상에 대한 상세한 정보 보존력이 뛰어나고 수행 시간 면에서도 우수함을 보였다.

• 한국산림과학회지
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• 제83권3호
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• pp.400-409
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• 1994

본 연구는 다양한 유형의 수림대가 갖는 소음감쇄효과를 측정하기 위하여 수행되었다. 차량통행이 빈번한 도로변 6개 조사지를 대상으로 측정한 결과 수림대의 소음감쇄효과를 확인하였다. 도로로부터 1m와 10m 상의 최대음압도의 차이는 10-15dB로 수림대의 속성에 따라 다소간의 차이를 보이고 있다. 초지를 대조구로 비교하였을 때 조사지 중에서 음압도의 최대차이는 밀생한 관목림에서 보이는 5dB 수준이다. 도로로부터 상향 경사면에 위치하는 조사지의 경우에는 오히려 대조구보다 소음감쇄 정도가 미미하였다. 연구를 통하여 분석된 제한된 정보와 국내외의 이전 연구결과를 토대로 단층 건물 주변의 10m 폭 방음수림대의 적절한 유형을 제시한다면 최소 3m 폭, 2m 수고의 밀식된 관목수림대와 앞뒤로 각각 3m 폭의 부드러운 초지의 조성을 들 수 있다. 위의 처방은 본 연구의 결과로 유추하여 볼 때 소음원인으로부터 발생되는 음압도를 15dB 이상 감소시킬 수 있을 것으로 판단된다.

• Nuclear Engineering and Technology
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• 제55권12호
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• pp.4570-4575
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• 2023

Noise and Radio-frequency interference or RFI causes a significant restriction on the Free induction Decay or FID signal detection of the Nuclear Quadrupole Resonance procedure. Therefore, using this method in non-isolated environments such as industry and ports requires extraordinary measures. For this purpose, noise reduction algorithms and increasing signal-to-noise-and-interference ratio or SNIR have been used. In this research, sodium nitrite has been used as a sample and algorithms have been tested in a non-isolated environment. The resonant frequencies for the 150 g of test sample were measured at 303 K at about 1 MHz and 3.4 MHz. The main novelty in this study was, (1) using two types of antennas in the receiver to improve adaptive noise and interference cancellation, (2) using a separate helical antenna in the transmitter to eliminate the duplexer, (3) estimating the noise before sending the pulse to calculate the weighting factors and reduce the noise by adaptive noise cancellation, (3) reject the interference by blanking algorithm, (4) pulse integration in the frequency domain to increase the SNR, and (5) increasing the detection speed by new pulse integration technique. By interference rejection and noise cancellation, the SNIR is improved to 9.24 dB at 1 MHz and to 7.28 dB at 3.4 MHz, and by pulse integration 44.8 dB FID signal amplification is achieved, and the FID signals are detected at 1.057 MHz and 3.402 MHz at room temperature.

• Safety and Health at Work
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• 제4권2호
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• pp.77-83
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• 2013

There is still a considerable burden of occupational diseases and injuries in the world. It is not well known which interventions can effectively reduce the exposures at work that cause this burden. The objective of this article is to summarize evidence from systematic reviews of interventions to prevent occupational diseases and injuries. We included systematic reviews of interventions to reduce the incidence of work-related cancer, dust-related diseases, occupational asthma, chronic obstructive pulmonary disease, noise induced hearing loss, back pain, and occupational injuries. We searched Medline and Embase with predefined search strategies to locate systematic reviews of these interventions. We found 23 systematic reviews of which the results are also applicable to low- and middle income countries. Effective measures to reduce exposure leading to work-related cancer, dust-related diseases, asthma, chronic obstructive pulmonary disease, noise, and injuries are available. However, better implementation of these measures is needed. Regulation, enforcement of regulation, and incentives for employers are effective interventions to achieve this goal. There is evidence that feedback and rewards for workers help in reducing occupational injuries. There is no evidence in many studies that back pain can be prevented. Personal protective equipment technically has the potential to reduce exposure but this is difficult to put into effect. There is no evidence in the studies regarding the effectiveness of education and training, preventive drugs, or health examinations. There is evidence that the implementation of technical measures enforced by regulation can prevent occupational diseases and injuries. For other interventions such as education or health examinations, there is no evidence that supports their effectiveness. More systematic reviews are needed in the area of injury prevention.

• 한국콘텐츠학회논문지
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• 제21권8호
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• pp.294-304
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• 2021

의료기관은 환자의 만족도 충족과 타 의료기관과의 경쟁력 향상을 위해 신축보다는 기존 병원 건물을 리모델링하게 된다. 의료기관 리모델링은 의료의 질과 환자 안전의 수준 향상을 위해 강화된 법과 제도로 인하여 점차 증가하고 있다. 다만 선행연구들은 의료기관 리모델링에 대해 건축적 요소 등 제한된 범위에서만 논의가 이루어졌다. 이에 본 연구는 의료기관 리모델링의 법적 제문제를 다각적으로 검토함으로써 향후 리모델링을 계획하는 의료기관에게 기본적인 자료를 제공하고자 한다. 의료기관 리모델링은 공사 여건의 제한으로 공사 기간이 길어지고, 환자에게 소음·분진 등의 피해를 발생시킨다. 따라서 사전에 환자의 피해를 예방하고 적정한 의료기관의 리모델링을 지원하는 방안이 필요하다. 이에 의료기관 리모델링 활성화 및 지원에 관한 법률 마련이 필요하다. 그리고 의료기관은 공사기준 자율 준수 체크리스트, 사전 방지조치 및 사후 개선조치, 병원 내 감염과 방사선 노출에 대한 대책을 마련해야 한다.

• 대한의용생체공학회:의공학회지
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• 제28권6호
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• pp.817-824
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• 2007

Tractography using Diffusion Tensor Magnetic Resonance Imaging (DT-MRI) is a method to determine the architecture of axonal fibers in the central nervous system by computing the direction of the principal eigenvector in the white matter of the brain. However, the fiber tracking methods suffer from the noise included in the diffusion tensor images that affects the determination of the principal eigenvector. As the fiber tracking progresses, the accumulated error creates a large deviation between the calculated fiber and the real fiber. This problem of the DT-MRI tractography is known mathematically as the ill-posed problem which means that tractography is very sensitive to perturbations by noise. To reduce the noise in DT-MRI measurements, a tensor-valued median filter which is reported to be denoising and structure-preserving in fiber tracking, is applied in the tractography. In this paper, we proposed the modified gradient descent method which converges fast and accurately to the optimal tensor-valued median filter by changing the step size. In addition, the performance of the modified gradient descent method is compared with others. We used the synthetic image which consists of 45 degree principal eigenvectors and the corticospinal tract. For the synthetic image, the proposed method achieved 4.66%, 16.66% and 15.08% less error than the conventional gradient descent method for error measures AE, AAE, AFA respectively. For the corticospinal tract, at iteration number ten the proposed method achieved 3.78%, 25.71 % and 11.54% less error than the conventional gradient descent method for error measures AE, AAE, AFA respectively.