• The Journal of the Acoustical Society of Korea
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• v.43 no.1
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• pp.19-28
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• 2024

This paper proposes a method to improve the performance of ship identification through lofargram analysis of ship noise by applying the Hough Transform to a Convolutional Neural Network (CNN) model. When processing the signals received by a passive sonar, the time-frequency domain representation known as lofargram is generated. The machinery noise radiated by ships appears as tonal signals on the lofargram, and the class of the ship can be specified by analyzing it. However, analyzing lofargram is a specialized and time-consuming task performed by well-trained analysts. Additionally, the analysis for target identification is very challenging because the lofargram also displays various background noises due to the characteristics of the underwater environment. To address this issue, the Hough Transform is applied to the lofargram to add lines, thereby emphasizing the tonal signals. As a result of identification using CNN models on both the original lofargrams and the lofargrams with Hough transform, it is shown that the application of the Hough transform improves lofargram identification performance, as indicated by increased accuracy and macro F1 scores for three different CNN models.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.15 no.3
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• pp.202-212
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• 2005

This study was aimed at rating the existing work environment noise components and alternatives in point of worker's view. To answer the purpose, AHP(Analytic Hierarchy Process) method is adopted in this research. Based on the AHP method, this research abstracts a mathematically rigorous noise components and alternative's weights and proven process for priority and decision-making. By reconstructing complex hearing conservation programs to a series of pair-wise comparisons, and then synthesizing the results, this study not only helps establishments of noise countermeasure, but also provides a clear rationale for noise alternatives. The result of this study is summarized as follows; 1) Job satisfaction index and noise identification index are 63, 56 respectively. 2) Noise level(15.7%), frequency(14.1%) and directivity(13.6%) are main reasons in worker's ground. 3) There are some difference between the estimation of worker's identification and that of work sites. 4) Low noise machine(14.7%), enclosure(13.2%) and shielding(9.6%) are chosen for noise protection method by workers. 5) Noise environment improvement should be focused on noise source rather than personal protection. 6) By the AHP method, noise source countermeasure have a key role at work environments.

• Transactions of the KSME C: Technology and Education
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• v.3 no.1
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• pp.63-69
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• 2015

Among the material handling system, EMS (Electric Monorail System), which is the facility of transferring the material hanging on truss, has the strength point of the maximum utilization of working space and the improvement of working environment including low-level noise generation. This paper will introduce the variable method of EMS rail analysis, which has the main role of supporting the whole material weight and guiding them with high-speed transportation, and, based on the analysis, the direction of optimization of the rail design be described. The rail with light-weight and high-strength contributes the reduction of the load of truss, the cost-down of rail production and the easy-installation on site.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.22 no.4
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• pp.75-82
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• 1986

A field experiment was carried out to clarify the effect of underwater sound on the luring of fish school. The effects of. the acoustic emission on the luring of fish school were checked actually at a set net fishing site in Namhae using a commercial acoustic equipment, Dairyo-8. An emitting system of sound was designed by the authors, and the ambient noise, the sound pressure level and the reaction of fish school were measured in the set net. 1. The predominent frequency band of ambient noise was 150Hz-400Hz,.and the sound emitted was 400Hz-100Hz. The sound pressure level of ambient noise in set net was higher at the landing part, and lower at the playgrond, the gate of court and "the enterance of inclined "passage. The ambient noise was increased with the time elapse-d at the stage of hauling net, but :it was decreased suddenly at the final stage due probably to the decrease of the swimming speed of the fish school. 2. The results of the observation and the recording paper of echo sounder indicate that the effect of emitting sound in the bag net of set net was remarkable for the luring of fish school in the early stage, but decreased after 30 minutes. The reaction of fish school is more sensitiv2 to the sound pressure level than the time intervals between the emission and the pause. For the purpos~ of practical use, it is nesessary to confirm what kind of sound pressure level is the best for the luring of fish school. 3. In response to the acoustic equipment(Dairyo-8), fish school started to swarm 20 minutes after the sound emission and scattered when the sound paused. As the emitting pattern of the acoustic equiment, the three seconds of emission after one second of pause was more effective than the continuous emission at the set net fishing ground. Catch of the fish(s during th~ sound ernissio:l at the gate of court was three to five times more than that of no emission.

• Proceedings of the Korean Society of Computer Information Conference
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• 2020.07a
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• pp.13-14
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• 2020

본 논문에서는 엣지 컴퓨팅 환경에서 머신러닝을 활용해 에스컬레이터 이상 감지 및 결함 분류를 하는 연구를 진행하였다. 엣지 컴퓨팅 기반 머신러닝을 사용해 에스컬레이터의 이상 감지 및 결함 분류를 위한 OneM2M환경을 구축하였으며 에스컬레이터에서 발생하는 소음에서 고장 유형에 따라 나타나는 주파수를 이용한다. Edge TPU를 활용해 엣지 컴퓨팅 시스템의 처리량을 최대화하고, 각 작업의 수행시간을 최소화함으로써 엣지 컴퓨팅 환경에서 이상 감지와 결함 분류를 수행할 수 있다.

• Korean Journal of Occupational Health Nursing
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• v.2
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• pp.40-51
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• 1992

본 연구는 병원에서의 산업보건관리 실태를 파악하기 위하여 전국에 있는 병원을 대상으로 1992년 12월 1일부터 1993년 1월 23일까지 설문조사를 설시하였다. 설문조사에 응당한 병원은 41개병원으로 회수율은 51.9%였다. 조사에 이용된 설문지는 산업안전보건법 내용을 기초로 하여 본 연구자가 작성한 것이며 안전보전에 관한 제반 규정, 안전보건관리체계, 근로자건강관리, 작업환경관리, 보건교육, 보건관련시설, 질병 및 상해에 대한 보상 등에 관한 45개문항으로 구성되어 있다. 분석결과는 다음과 같다. 첫째, 전체 병원 중 68.3%가 안전보건관리 규정이 있다고 답하였으며, 77.5%의 병원이 단체협약 중 근로자의 안전과 보건에 관한 조항을 포함시키고 있는 것으로 나타났다. 단체협약에 포함된 내용 중에는 정기건강진단(23.7%)과 질병 및 상해에 대한 보상(20.9%), 안전보건위원회의 구성(18.1%)등이 많았다. 둘째, 대상 병원중 66.7%가 안전보건관리책임자, 관리감독자, 안전담당자를 두고 있는 것으로 나타났고, 근로자수가 1,000명 이상인 병원은 83.3%가 이들 인력을 선임하고 있다. 그러나, 보건관리자와 안전관리자를 전담으로 두고 있는 경우는 한 곳도 없었으며 50%이내에서 겸직으로 선임하고 있었다. 또한, 안전보건위원회를 운영하고 있거나 노사협의회로 이를 대치하고 있는 병원은 54.2%로 절반 수준에 머물렀고, 그나마 정기적으로 운영을 하고 있다고 답한 병원은 3개 병원 밖에 되지 않았다. 세째, 근로자 건강관리를 위한 건강진단 실시 현황을 보면, 채용시검진 97.6%, 일반건강진단 100.0%, 특수 건강진단 24.4%가 실시하고 있었다. 건강진단에서 주로 실시하고 있는 항목은 흉부 X선검사, 시력, 혈압, 혈청GOT/GPT, 체중, 신장등이었다. 그러나, 병원에서 감염될 수 있는 기회가 높은 간염항원/항체검사의 실시율은 85.7%로 아직도 실시하지 않는 병원이 있음을 알 수 있다. 네째, 작업환경관리를 위하여 정기적으로 환경측정을 실시하는 병원은 21.6%였고 주로 측정하는 항목은 방사선이었다. 특히 소음, 조명, 분진에 대한 측정이 이루어지지 않음은 근로자뿐아니라 환자의 안위에도부정적인 영향을 미칠 수 있다. 다섯째, 안전한 작업과 근로자의 건강을 위하여 정기적인 보건교육을 설시하고 있는 병원은 불과 5.6%였다. 교육내용은 주로 안전에 관한 것이었다. 여섯째, 근로자의 일상적인 건강문제를 해결해주는 의무실을 독립적으로 마련하고 있는 병원은 한 곳도 없었고, 교대근무자나 당직자를 위한 수면시설은 44.7%, 작업 후에 사용할 수 있는 샤워시설은 35.1%의 병원이 마련하고 있었다. 일곱째, 근무중 다치거나 병에 걸렸을 때 치료비에 대한 부담은 대체로 병원이 하고 있으며 치료기간 중 근무는 병가나 휴직으로 처리되고 있다. 이는 병원이 산재보상보험법에 적용을 받지 않은 사업으로 분류되어 있는 현실에 기인된 것으로 보상과 관련된 부담을 병원이나 근로자 모두가 안게 되는 결과를 초래하게 되는 것이다. 이상에서 볼 때 병원근로자를 위한 산업보건관리는 주로 건강진단과 질병 및 상해에 대한 보상제도가 이루어지고 있는 실정이다. 그러므로 질병의 예방이나 악화방지 나아가 건강증진을 도모하기 위한 지속적인 노력을 기울이고 있는 병원은 전무한 상태임을 알 수 있다. 이러한 현실을 병원근로자를 위한 산업보건관리에 대한 인식이 전반적으로 부족함을 드러내는 것으로 이를 개선하기 위한 보다 적극적인 노력이 시급히 요청되고 있다.

• The Korean Journal of Nuclear Medicine Technology
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• v.14 no.1
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• pp.61-66
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• 2010

Purpose: Recently, Department of Nuclear Medicine have an interest in Video Display Terminals (VDT) syndrome including musculoskeletal disorders, ophthalmologic disorders, trouble of electromagnetic waves and stress disorders occur to VDT workers as the growing number of users and rapid pace of service period supply in large amount. This study research on the actual condition for VDT syndrome in Nuclear Medicine, Seoul National University Hospital (SNUH), discover the problem and draw a plan of upcoming improvement. The aim of this study establish awareness about VDT syndrome and is to prevent for it in the long run. Materials and Methods: Department of Nuclear Medicine, SNUH is composed Principle part, Pediatric part and PET center. We estimated risk factors visit in each part directly. Estimation method use "Check list for VDT work" of Wonjin working environment health laboratory and check list is condition of VDT work, condition of work tables, condition of chairs, condition of keyboards, condition of monitors, working position, character of health management and other working environment. Analysis result is verified in Department of Occupational and Environment, Hallym University Sacred Heard Hospital. Results: As a result of analysis, VDT condition of Department of Nuclear Medicine, SNUH is rule good. In case of work tables, recent of things are suitable to users upon the ergonomical planning, but 15% of existing work tables are below the standard value. In case of chairs are suitable, but 5% of theirs lost optimum capacity become superannuated. The keyboards are suitable for 98% of standard value. In case of monitors, angle control of screen is possible of all, but positioning control is impossible for 38%. In case of working position, 10% is fixed positioning for long time and some of the items researched unsuitable things for standard. At health management point, needed capable of improvement. Also, other working condition as lighting, temperature, noise and ventilation, discovered the problem, but is sufficient to advice value. Conclusion: VDT syndrome is occurrences of possibility continuously, come economical expensive about improvement, is inherent in various causes and originate without your knowledge. So, there is need systematic management system. In Nuclear Medicine, VDT syndrome make it better that constant interest and effort as improvement of ergonomical working environment, improvement of working procedure, regular exercise and steady stretching, and can be prevented fairly. This promote physical and mental condition of worker in top form in comfortable working environment, so this is judged by enlargement of operations efficiency and rising of satisfaction ratings of the inside client.

• Explosives and Blasting
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• v.27 no.1
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• pp.38-46
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• 2009

Recently, as a reduction method of vibration and noise, an electronic detonation which has an accuracy of time and a freedom of input delay time was introduced. A waveform composition program can determine a delay time and accomplish simulation under environment similar to real blast using a delay time. In this study, optimum delay time which controls vibration is obtained and real measurement vibration level is estimated by a waveform composition program.

• Explosives and Blasting
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• v.30 no.2
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• pp.1-8
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• 2012

The only law related to airblast and ground vibration control in Korea is the Noise and Vibration Control Act enforced by the Ministry of Environment. But this law mainly deals with the annoyance aspects of noises and vibrations in ordinary human life. Hence, the law defines the safety criteria of ground vibration as the vibration level (VL) of dB(V) unit. The ground vibrations produced from blasting, however, have the unique characteristics that can be shown in shock vibrations, and the duration is also very short compared to the vibrations from machinery, tools or facilities. Hence, vibration regulations for blasting operations usually define the safety criterion as the peak particle velocity (PPV) considering the effect of ground vibrations to structural damage. Notwithstanding, there are several attempts that predict VL from PPV or estimate VL based on the scaled distances (SD; in unit of $m/kg^{1/2}$ or $m/kg^{1/3}$) without considering their frequency spectra. It appears that these attempts are conducted mainly for the purpose of satisfying the law in blasting contracts. But, in principle there could no correlation between peaks of velocity and acceleration over entire frequency spectrum. Therefore, such correlations or estimations should be conducted only for the waves with the same or very similar frequency spectra.

• Explosives and Blasting
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• v.36 no.2
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• pp.19-26
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• 2018

The measures for environmental regulations have become more strict over the recent years. Due to vibration and noise arising from blasting, every site that chooses to handle explosives has to be under certain restrictions in its use. Especially a site where a safety thing is situated within close proximity, the chosen method is through mechanical excavation. However, various applications of electronic detonators has made blasting possible where mechanical excavation used to be the only alternative. Hanwha Corporation has developed an electronic detonator, $HiTRONIC^{TM}$, which is an advanced fourth-generation detonator with a high accuracy of delay time(0.01%). At this moment, $HiTRONIC^{TM}$ is widely used in highway and railway construction sites, large limestone quarries, and many other blasting sites where blasting had not been an available option before. In this paper, I would like to introduce a case study on construction of utilizing $HiTRONIC^{TM}$ at a large-scale tunnel site.