• 제목/요약/키워드: Machinery noise

검색결과 566건 처리시간 0.028초

기계시각을 이용한 분무입자크기 측정 (Machine Vision Instrument to Measure Spray Droplet Sizes)

  • 전홍영;티안레이
    • Journal of Biosystems Engineering
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    • 제35권6호
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    • pp.443-449
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    • 2010
  • A machine vision-based instrument to measure a droplet size spectrum of a spray nozzle was developed and tested to evaluate its accuracy on measuring spray droplet sizes and classifying nozzle sizes. The instrument consisted of a machine vision, light emitting diode (LED) illumination and a desktop computer. The illumination and machine vision were controlled by the computer through a C++ program. The program controlled the machine vision to capture droplet images under controlled illumination, and processed the droplet images to characterize the droplet size distribution of a spray nozzle. An image processing algorithm was developed to improve the accuracy of the system by eliminating random noise and out-of-focus droplets in droplet images while measuring droplet sizes. The instrument measured sizes of the three different balls (254.0, 497.8 and $793.8\;{\mu}m$) and the measurement ranges were $241.2-273.6\;{\mu}m$, $492.9-529.6\;{\mu}m$ and $800.8-824.1\;{\mu}m$ for 254.0-, 497.84- and $793.75-\;{\mu}m$ balls, respectively. Error of the measured droplet mean was less than 3.0 %. Droplet statistics, $D_{V0.1}$, $D_{V0.5}$ and $D_{V0.9}$, of a reference nozzle set were measured, and droplet size spectra of five spray nozzles covering from very fine to extremely coarse were measured to classify spray nozzle sizes. Ninety percent of the classification results of the instrument agreed with manufacturer's classification. A comparison study was carried out between developed and commercial instruments, and measurement results of the developed instrument were within 20 % of commercial instrument results.

경인지역 일부 5인미만 사업장 근로자의 작업환경실태와 관리대책 (The Current Status and Recommendation of Work Environment Management in Small Scale Industry with less than 5 Workers)

  • 김대식;노영만;김현욱;정춘화;유기호
    • 한국산업보건학회지
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    • 제11권3호
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    • pp.179-189
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    • 2001
  • This study was performed to identify the current status of work environment management and to provide appropriate recommendations for small scale industry with less than 5 workers from September, 2000 to October, 2000 in Seoul city and Gyoung-gi province. The 211 companies were surveyed by checklist included the elements of management of work environment, hazardous chemicals, MSDS, personal protective equipment, and ventilation system. The proportion of metal products manufacturing and printing industries are 25.6 % and 22.3%, respectively. The daily working hours in printing industry is longer than others. The industries that produce potentially hazardous agents, such as noise, dust, metal, organic solvents, radiation and chemical material are pulp, plating, machinery, and printing, respectively. In above industries, only 2.8 % of those recognised and had MSDS. The proportion of companies providing fire extinguishers, safety showers are found to be 13.3 %, 7.1 %, respectively. Only 24.2 % of companies provided personal protective equipment to the workers. The ventilation system was operated in most of companies. But local exhaust ventilation system is provided to 22.3 % of those, also had not been annually inspected. This study showed that the current status of occupational safety and health was not appropriate for workers in small scale industries. It is suggested that annual physical examination have to be performed, MSDS usage must become widespread, and employer and emplyees in small scale industry should be educated for the treatment and storage of hazardous chemicals to improve the occupational safety and health of the working environment. also, regulatory standard has to be applied to local exhaust ventilation system in small scale industry to improve the working condition.

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Atomic norm minimization을 통한 수중 방사 소음 신호의 토널 주파수 탐지 (Detection of tonal frequency of underwater radiated noise via atomic norm minimization)

  • 김준한;김진홍;심병효;홍정표;김성일;홍우영
    • 한국음향학회지
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    • 제38권5호
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    • pp.543-548
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    • 2019
  • 수중 표적의 기어박스 및 보조 장치 등으로부터 방사되는 토널 신호의 주파수 성분은 처리하고자 하는 주파수 대역에 비해 상대적으로 적어 희소신호로 모델링될 수 있다. 근래에 토널 신호의 주파수 희소성을 이용하여 빠른 시간 내에 적은 수의 관측치로 토널 주파수를 복원하는 압축센싱 기반의 연구가 활발히 진행되고 있다. 기존의 방법들은 이산(discrete) 주파수 영역에서 주파수를 검출하기 때문에 이산화로 인한 basis mismatch error가 불가피하다. 본 논문에서는 atomic norm minimization을 이용하여 적은 수의 관측치로 연속(continuous) 주파수 영역에서 토널 주파수를 검출하는 기법을 제안한다. 모의실험을 통해 기존의 기법들에 비해 제안하는 기법의 성능이 정확성과 평균제곱오차 측면에서 우수함을 확인하였다.

설비공학 분야의 최근 연구 동향 : 2007년 학회지 논문에 대한 종합적 고찰 (Recent Progress in Air Conditioning and Refrigeration Research : A Review of Papers Published in the Korean Journal of Air-Conditioning and Refrigeration Engineering in 2007)

  • 한화택;신동신;최창호;이대영;김서영;권용일
    • 설비공학논문집
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    • 제20권12호
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    • pp.844-861
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    • 2008
  • The papers published in the Korean Journal of Air-Conditioning and Refrigeration Engineering during the year of 2007 have been reviewed. Focus has been put on current status of research in the aspect of heating, cooling, ventilation, sanitation and building environments. The conclusions are as follows. (1) The research trends of fluid engineering have been surveyed as groups of general fluid flow, fluid machinery and piping, etc. New research topics include micro nano fluid, micropump and fuel cell. Traditional CFD was still popular and widely used in research and development. Studies about fans and pumps were performed in the field of fluid machinery. Characteristics of flow and fin shape optimization are studied in the field of piping system. (2) The research works on heat transfer have been reviewed in the field of heat transfer characteristics, heat exchangers, and desiccant cooling systems. The research on heat transfer characteristics includes thermal transport in pulse tubes, high temperature superconductors, ground heat exchangers, fuel cell stacks and ice slurry systems. For the heat 'exchangers, the research on pin-tube heat exchanger, plate heat exchanger, condensers and gas coolers has been cordially implemented. The research works on heat transfer augmenting tubes have been also reported. For the desiccant cooling systems, the studies on the design and operating conditions for desiccant rotors as well as performance index are noticeable. (3) In the field of refrigeration, many papers were presented on the air conditioning system using CO2 as a refrigerant. The issues on the two-stage compression, the oil selection, and the appropriate oil charge were treated. The subjects of alternative refrigerants were also studied steadily. Hydrocarbons, DME and their mixtures were considered and various heat transfer correlations were proposed. (4) Research papers have been reviewed in the field of building facilities by grouping into the researches on heat and cold sources, air conditioning and air cleaning, ventilation and fire research including tunnel ventilation, flow control of piping system, and sound research with drain system. Main focuses have been addressed to the promotion of efficient or effective use of energy, which helps to save energy and results in reduced environmental pollution and operating cost. (5) Studies were mostly focused on analyzing the indoor environment in various spaces like cars, old tombs, machine rooms, and etc. in an architectural environmental field. Moreover, subjects of various fields such as the evaluation of noise, thermal environment, indoor air quality and development of energy analysis program were researched by various methods of survey, simulation, and field experiment.

지반진동 규제기준에서 진동레벨과 진동속도의 상호관계에 대한 고찰 (Consideration on the Relation between Vibration Level and Peak Particle Velocity in Regulation of Ground Vibration)

  • 최병희;류창하
    • 화약ㆍ발파
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    • 제30권2호
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    • pp.1-8
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    • 2012
  • 국내에서 발파풍과 지반진동을 취급하는 유일한 법규가 바로 환경부의 소음진동관리법이다. 하지만 이 법규는 생활소음과 생활진동을 주로 취급하고 있으므로 지반진동에 대한 안전기준을 dB(V) 단위의 진동레벨에 의해 규정하고 있다. 그러나 발파로 발생되는 지반진동은 충격진동에서 볼 수 있는 것과 같은 독특한 특성을 지니고 있으며, 그 지속시간도 기계류나 장비류, 시설물 등에서 발생하는 진동과 비교하여 매우 짧은 특성이 있다. 그러므로 발파작업에 대한 진동법규에서는 통상 구조물 손상에 대한 지반진동의 영향을 고려하여 안전기준을 최대입자속도(peak particle velocity; PPV)로 설정한다. 그럼에도 불구하고 진동파동의 주파수 스펙트럼에 대한 충분한 고려도 없이 PPV로부터 진동레벨(vibration level; VL)을 예측하거나 $m/kg^{1/2}$이나 $m/kg^{1/3}$ 단위의 환산거리에 따라 VL을 추정하려는 시도들이 있다. 이 시도들은 주로 발파공사 과정에서 소음진동관리법을 충족시키려는 목적으로 이루어지는 것으로 보인다. 그러나 원칙적으로 전체 주파수 스펙트럼 상에서는 속도나 가속도 피크치 사이에는 아무런 상관관계도 존재할 수 없다. 따라서 이러한 상관관계나 추정식의 유도작업은 반드시 동일하거나 매우 유사한 주파수 스펙트럼을 지니는 파동들에 한해서 수행되어야 한다.

진동 데이터 기반 설비고장예지를 위한 신호처리기법 (A Signal Processing Technique for Predictive Fault Detection based on Vibration Data)

  • 송예원;이홍성;박훈석;김영진;정재윤
    • 한국전자거래학회지
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    • 제23권2호
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    • pp.111-121
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    • 2018
  • 항공기 엔진, 풍력발전기, 모터 등 회전기기에서 발생하는 많은 문제들은 진동이나 소음과 같은 신호 데이터를 측정하여 이상감지를 할 수 있으며, 주파수 분석 등 여러 가지 신호처리가 데이터 전처리 단계에서 필요하다. 본 논문에서는 진동 데이터를 분석하여 설비 이상상태를 감지하는 기법을 소개한다. 정상상태 데이터를 기반으로 마할라노비스 거리를 측정하여 이상상태 유무를 모니터링 하는 방식을 사용한다. 특히 신호 데이터의 전처리 기법들을 도입하여 이상상태 감지의 성능을 개선할 수 있음을 보여준다. 전처리 단계에서 신호 데이터 수집 과정에서 발생한 누설오차(leakage)를 없애기 위해 해밍 윈도우(Hamming window)를 적용하고, 신호 데이터의 원신호인 포먼트(formant)를 분리하기 위하여 켑스트럼(cepstrum) 분석을 실시한다. IMS 베어링 진동 공개데이터를 대상으로 시간 구간별로 6가지 통계지표를 추출한 후 마할라노비스 거리 분류기를 적용하여 성능을 검증하였다. 제시된 신호처리 전처리 기법을 적용함으로써 성능이 획기적으로 향상되는 것을 실험에서 보여주었다.

굴삭기 Front Support 부품 뒤틀림 결함 최소화 방안 도출 (A study on excavator front support parts to minimize springback defects)

  • 전용준;허영무;이하성;김동언
    • Design & Manufacturing
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    • 제12권2호
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    • pp.40-45
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    • 2018
  • Recently, in construction equipment machinery production, development has focused on environmentally-friendly functions to improve existing production capacity. For excavators as well, emphasis has been placed on response to environmental regulations, miniaturization, and noise reduction, while technology is being developed considering cost reduction and safety.Accordingly, the front support, an inner reinforcement part of the excavator, as well as high-strength steel plates to improve safety and reduce weight, are being applied.However, in the case of high-strength materials, Springback occurs in the final formed part due to high residual stress during product forming. Derivation of a forming or product shaping process to reduce springback is needed. Accordingly, regarding the front support, an inner reinforcement part of the excavator, this study derived a method to improve springback and secure shape stiffness through analysis of the springback occurrence rate and springback causes through a forming analysis.As for the results of analyzing the springback occurrence rate of existing products through forming analysis, springback of -22.6 mm < z < 27.35 mm occurred on the z-axis, and it was confirmed that springback occurred due to the stiffness reinforcing bead of the upper and middle parts of the product.To control product residual stress and springback, we confirmed a tendency of springback reduction through local pre-cutting and stiffness reinforcement bead relocation.In the local pre-cutting model, springback was slightly reduced by 5.3% compared with the existing model, an insignificant reduction effect. In the stiffness reinforcement bead relocation model, when an X-shaped stiffness reinforcement bead was added to each corner portion of the product, springback was reduced by at least 80%.The X-shaped bead addition model was selected as the springback reduction model, and the level of stiffness compared to the existing model was confirmed through a structural analysis.The X-shaped bead additional model showed a stress springback of 90% and springback reduction of 7.4% compared with the existing model, indicating that springback and stiffness will be reinforced.

수리모형실험을 통한 펌프 흡입배관부 보텍스 현상 저감방안 (The plan of depreciation vortex developing a Pump suction Pipes through Sump model test)

  • 안인수;김성호;김경엽;노형운;이영호
    • 유체기계공업학회:학술대회논문집
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    • 유체기계공업학회 2004년도 유체기계 연구개발 발표회 논문집
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    • pp.193-198
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    • 2004
  • 펌프장 흡입수조에서 발생되는 보텍스의 구조를 Sump Model Test와 PIV 방법을 수행하여 보텍스 발생여부를 검증한 결과는 아래와 같다. 1) 현장조사의 결과 취수장 대부분의 흡수정 구조가 유체역학적으로 보텍스를 발생시키는 구조였음을 알 수 있었으며 흡수정의 형태를 흡입구와 수문이 일직선으로 되어 있는 토목구조를 가진 펌프장이 경유는 보텍스 발생이 비교적 적었음을 알 수 있었다. 이는 토목구조의 설계가 펌프과정에 따른 흡수정 내의 유동장을 고려하여 볼 때 매우중요하다는 것을 알 수 있다. 2) JSME S 004-1984를 토대로 1/8 모델내에서 모형수리실험을 수행한 결과 현장에서 발견된 결과와 같이 예측되었다. 또한, 모든 상사조건 일치에서 수위나 운전대수 및 호기조합에 따라 정도의 차이는 있으나 모든 경우에 보텍스가 심하게 발생하고 있음을 알 수 있었다. 3) PIV 실험에서 볼 수 있듯이 자유표면 보텍스는 $\sharp$1 호기와 $\sharp$3 호기에서 주로 발견되었는데 이는 $\sharp$3 호기 흡입구 바로 전방에 있는 취수구의 영향으로 강한 회전흐름이 수조 내에서 형성되기 때문으로 보여진다. 4) 보텍스의 발생은 펌프 소음발생 임펠러 수명 및 성능에 나쁜 영향을 주기 때문에 반드시 Anti Vortex Device를 설치하여 보텍스의 발생을 저감시켜야 한다.

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원격 크레인 와이어 로프 결함 탐지 시스템 개발에 관한 연구 (A Study on Development of Remote Crane Wire Rope Flaws Detection Systems)

  • 민정탁;이진우;이권순
    • 한국항해항만학회지
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    • 제27권1호
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    • pp.97-102
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    • 2003
  • 와이어 로프는 엘리베이트, 건설현장의 리프트, 현수교 등 다양한 산업 현장에 응용되어 지고 있다. 특히, 크레인의 와이어 로프는 컨테이너 이송에 중용한 요소로서 컨테이너 이송 시 로프에 결함이 발생한다면 안전사고, 생산성 저하에 따른 경제력 손실 그리고 컨테이너 터미널의 경쟁력 손실 등 여러 가지 문제점이 초래된다. 이러한 문제점을 해결하기위해 원격 크레인 와이어 로프 결함 탐지 시스템을 개발하였으며, 본 시스템은 크게 결함 탐지부, 신호 처리부, 원격 모니터링부로 구성되어져 있다. 측정된 신호는 외부적 환경으로부터 노이즈를 가지게 되는데 원신호로부터 이러한 노이즈를 제거하기 위하여 이산 웨이브렛 변환을 적용하였다. 그 결과 와이어 로프 결함을 탐지하는데 있어서 좀더 쉽게 결함을 판별할 수 있었다. 결론적으로 이러한 시스템의 개발은 와이어로프의 교체 시기 연장으로 항만의 비용을 절감할 수 있으며, 경쟁력 향상 그리고 엘리베이터, 리프트 등 다양한 산업현장에 이러한 시스템을 적용할 수 있다.

노동생산성 향상을 위한 유해작업환경관리에 관한 연구 (A study on the management of harmful working environments for Increase of Labor productivity.)

  • 조태웅;유익현;박성애
    • 한국환경보건학회지
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    • 제3권1호
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    • pp.27-44
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    • 1976
  • This study was carried out to evaluate the harmful factors in working environments and to investigate the labor productivity after improvement of environments, surveying 93 industrial establishments of 10 industries located in Youngdeungpo industrial area in Seoul. The results obtained were as follows: 1) The highest noise level of 125dB(A) was indicated at the rolling process of transport equipment manufacturing industry. 2) The best illumination level was shown in precise machinery industry and the worst was indicated in rubber products, metallic products and transport equipment manufacturing industries. 3) Thermal conditions were above threshold limit value (TLV) at more than two processes of all industries except printing industry. 4) The highest dust concentration was determined in textile and wearing manufacturing industry. 5) Organic solvents were detected at 52 processes in 93 industrial establishments and 33 processes of them showed higher than TLV. The results about harmful chemicals were as follows: a) sulfur dioxide ($SO_2$)was determined higher than TLV on welding process of metallic product manufacturing industry and heat treatment process of transport equipment manufacturing industry. b) Carbon monoxide (CO) concentration was 700ppm at heat treatment process of transport equipment manufacturing industry, indicating 14 times of TLV. c) vinylchloride concentration in the air of PVC raw material mixing process and PVC preparation process of chemical product manufacturing industry was determined higher than TLV. d) Hydrochloride (HCl) concentration in the air of wire expanding process of transport equipment manufacturing industry was determined higher than TLV. 7) Higher values of lead concentration than TLV were determined at lead welding metallic product manufacturing industry and type planting process of process of printing industry, $1.8mg/m^3$ and $0.3mg/m^3$ respectively. 9) 22, 968 of 52, 855 workers (i.e. 43.5%) in 93 industries were exposed to various harmful agents. 10) It was found that the improvement of illumination in electric apparatus manufacturing industry (from 20~40 lux to 420 lux) resulted in an increase in productivity of 6.5% per capita and a decrease in faulty products of 19%. 11) Improvement of environments using local exhaust ventilation system resulted in a decrease of harmful substances lower than TLV and an increase in productivity of 11.4%. 12) Improvement of shovelling tools based on ergonomics resulted in a reduction in energy expenditure of 25.3% and an increase in productivity of 32.2% per capita.

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