• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.15 no.1
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• pp.52-60
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• 2005

This study was carried to assess the accuracy of material safety data sheets (MSDS) for some water-soluble metalworking fluid (MWF) with respect to mono- ethanolamine(MEA), di-ethanolamine(DEA) and tri-ethanolamine (TEA). 39 fresh and 52 used MWFs for this study were taken from the workplace. The quantification and qualification of MEA, DEA and TEA were done using ion-chromatography. Three main findings of this study were 1) EA that was not addressed in material safety & data sheets (MSDS) was found to be enough higher than 1%, 2) 33.3% of 39 fresh MWF showed ingredient and concentration of MEA, DEA and TEA in MSDS and 3) the concentrations of MEA(20.5%), DEA(41.3%) and TEA(15.4%) were much higher than those indicated in MSDS. Consequently, we concluded that the accuracy on ingredients and concentrations of MEA, DEA and TEA provided in MWF was very low. Our study recommends that the limit concentration of chemical except for carcinogen that employer has to indicate in MSDS should be lowered from 1% to 0.1% .

• ETRI Journal
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• v.32 no.6
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• pp.921-931
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• 2010

It has been shown that the principal subspace-based multichannel Wiener filter (MWF) provides better performance than the conventional MWF for suppressing interference in the case of a single target source. It can efficiently estimate the target speech component in the principal subspace which estimates the acoustic transfer function up to a scaling factor. However, as the input signal-to-interference ratio (SIR) becomes lower, larger errors are incurred in the estimation of the acoustic transfer function by the principal subspace method, degrading the performance in interference suppression. In order to alleviate this problem, a principal subspace modification method was proposed in previous work. The principal subspace modification reduces the estimation error of the acoustic transfer function vector at low SIRs. In this work, a frequency-band dependent interpolation technique is further employed for the principal subspace modification. The speech recognition test is also conducted using the Sphinx-4 system and demonstrates the practical usefulness of the proposed method as a front processing for the speech recognizer in a distant-talking and interferer-present environment.

• IEMEK Journal of Embedded Systems and Applications
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• v.3 no.1
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• pp.1-7
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• 2008

In this paper, a MSS-NOVO method that combines the HMM composition method with a noise reduction method is proposed for speech recognition in noisy environments. This combined method starts with noise reduction with modified spectral subtraction (MSS) to enhance the input noisy speech, then the noise and voice composition (NOVO) method is applied for making noise adapted models by using the noise in the non-utterance regions of the enhanced noisy speech. In order to evaluate the effectiveness of our proposed method, we compare MSS-NOVO method with other methods, i.e., SS-NOVO, MWF-NOVO. To set up the noisy speech for test, we add White noise to KLE 452 database with different SNRs range from 0dB to 15dB, at 5dB intervals. From the tests, MSS-NOVO method shows average improvement of 66.5% and 13.6% compared with the existing SS-NOVO method and MWF-NOVO method, respectively. Especially our proposed MSS-NOVO method shows a big improvement at low SNRs.

• Proceedings of the Korean Environmental Health Society Conference
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• 2001.04a
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• pp.97-98
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• 2001

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.24 no.4
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• pp.416-424
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• 2014

Objectives: The objective of this study is to analyze the predominant microorganisms in the industry treating MWFs(Metal working fluids). Methods: The bacteria and fungi were collected by agar plate impaction and bulk MWFs in storage tank at 54 sites in 9 shops in South Korea. The dominant bacteria and fungi isolated from agar media were identified by fatty acid analysis and morphological analysis, respectively. Results: Totally 111 dominant bacteria were identified in the process, outdoor, and bulk MWFs. The predominant bacterial genus was Micrococcus and Bacillus in the process and outdoor, Pseudomonas in bulk MWF. Among the identified 119 strains of fungi, Cladosporium and Penicillium genus were dominated. The ratios of bacteria designated biosafety level 2 and 1 were 30% and 21%, respectively. Conclusions: This study has investigated the dominant microorganisms in soluble MWF using industry. And it was useful that the qualitative evaluation method along with quantitative analysis for better understanding of the biological factors in the work environment.

• Smart Media Journal
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• v.7 no.3
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• pp.9-15
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• 2018

This paper proposes an optimal gain modification method of the Multichannel Wiener filter (MWF) using speech presence probabilities. Conventional gain modification methods of MWFs have the problem of the increase of speech distortions while reducing residual noises with its relative heuristic approach. However, the proposed optimal gain modification method, derived by solving the unconstrained minimization problem of the probability-involved cost function, reduces amounts of residual noises and signal distortions simultaneously. Through an evaluation of the filtered waveforms and spectrograms, it is verified that the proposed method results in an improved SNR with less signal distortions compared to the conventional MWF.

• Proceedings of the Korean Institute of Industrial Safety Conference
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• 1998.11a
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• pp.99-104
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• 1998

산업현장에서 많이 쓰이는 절삭설비(Metal Working : MW)는 매우 다양하여 일일이 열거하기는 어렵고 주로 자동차생산업종, 농기구제조업종, 각종 기계기구 생산업종, 경금속가공업종 등에서 매우 광범위하게 사용되고 있다. 이들 업종에서 연마, 절단, 천공, 드릴링, 터닝(turning)등을 수행하는 많은 근로자들이 다량의 MWF(Metal Working Fluids) 뿐만 아니라 열악한 소음환경에 노출되고 있다. (중략)

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2001.11a
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• pp.293-294
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• 2001

자동차 엔진을 구성하는 소재 가공시에 냉각, 절삭용구와 가공표면의 용접현장(welding), 고온에서의 마모방지와 잔열로 인한 비틀림(distortion) 방지 등을 목적으로 사용되는 수용성(soluble) MWFs (Metalworking Fluids)의 기능에 필요한 구성물질인 기유(base oil)와 첨가제(additive)가 건강상 장해를 유발한다고 알려지고 있다(김신범, 1997). 하지만 수용성 MWFs를 사용하여 소재를 가공하는 산업현장에서는 MWFs 미스트 발생제어를 공정 상부에 외부식 후드를 국소적으로 설치하는 것이 일반적인 방법이다(Fig.2). (중략)

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.23 no.3
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• pp.169-176
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• 2013

Objectives: The aim of this study is to critically review the health effects of not only direct exposure to biocide, but also indirect exposure to by-product hazardous agents generated through the use of biocide in metalworking operations. Methods: An extensive literature review was conducted of studies reporting on respiratory disease cases, particularly hypersensitivity pneumonitis (HP), in environments using water-soluble metalworking fluids (MWFs). Keyword search terms included 'metalworking fluids', 'machining fluids', 'metalworking operation' 'machining operation' and 'biocide', which were also used in combination. Additional articles were identified in references cited in the articles reviewed. Results: Several of the field, epidemiological and experimental studies reviewed assumed that the symptoms and signs typical of HP developed in machinists who handled water-soluble MWF could be caused by inhalation exposure to nontuberculous mycobacteria (NTM). Most NTM are known to be not only resistant to both biocide and disinfectant, but also to have acid-fast cell walls that are highly antigenic. The presence or persistence of the Mycobacterium species, referred to as NTM, in metalworking fluid-using operations may be caused by NTM contamination in either the natural water or tap water that is used to dilute the base oil and additives for water-soluble MWFs. This hypothesis that NTM contamination in water-soluble MWFs is a causative agent of HP has high biologic plausibility, such as antigenic property, hydrophobicity and small diameter (< 5 um). Conclusions: Aerosolized mycobacteria colonized from MWF are likely to be causing the HP. Inhalation exposure to mycobacteria should be considered as a possible cause for the development of HP.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2003.11a
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• pp.531-532
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• 2003

공작기계 가동시 윤활과 냉각 등의 목적으로 다양한 종류의 금속가공유 (MWFs : 절삭유, 윤활유, 방청유 둥)를 사용하고 있다. MWFs에는 포름알데히드, 니트로스아민, 염화파라핀 등의 발암물질이 포함되어 있는 것으로 알려져 있어 작업자 건강보호를 위해 효율적인 환기가 요구되고 있다. 현장에서 가장 많이 사용하고 있는 포켓 필터형 오일미스트 콜렉터는 제진 장치가 없기 때문에 필터 표면에 한번 부착된 오일 미스트와 먼지가 떨어지지 않기 때문에 일정시간 후 필터 표면에 막힘 현상이 발생한다. 필터 표면이 막히면 차압 증가와 함께 송풍량이 감소하기 때문에 미스트 제거 효율이 크게 저하되고, 결과적으로 오일미스트의 환기 효율이 크게 감소된다.(중략)