• 제목/요약/키워드: Crystalline Silica

검색결과 107건 처리시간 0.018초

Effect of Silica Content on the Dielectric Properties of Epoxy/Crystalline Silica Composites

  • Park, Jae-Jun
    • Transactions on Electrical and Electronic Materials
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    • 제13권6호
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    • pp.322-325
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    • 2012
  • Crystalline silica was synthesized by annealing amorphous silica at $1,300^{\circ}C$ or $1,400^{\circ}C$ for various times, and the crystallinity was estimated by X-ray diffraction (XRD) analysis. In order to prepare a low dielectric material, epoxy/crystalline silica composites were prepared, and the effect of silica content on the dielectric properties was studied under various functions of frequency and ambient temperature. The dielectric constant decreased with increasing crystalline silica content in the epoxy composites, and it also decreased with increasing frequency. At 120 Hz, the value of 5 wt% silica decreased by 0.25 compared to that of 40 wt% silica, and at 23 kHz, the value of 5 wt% silica decreased by 0.23 compared to that of 40 wt% silica. The value increased with increasing ambient temperature.

국내 업종별 결정형 유리규산 노출 평가 (Evaluation of Crystalline Silica Exposure Level by Industries in Korea)

  • 연동은;최상준
    • 한국산업보건학회지
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    • 제27권4호
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    • pp.398-422
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    • 2017
  • Objectives: The major aim of this study is to construct the database of retrospective exposure assessment for crystalline silica through reviews of literatures in South Korea. Methods: Airborne concentrations of crystalline silica were collected using an academic information search engine, Research Information Service System(RISS), operated by the Korea Education & Research Information Service(KERIS). The key words used for the literature search were 'silica', 'crystalline silica', 'cristobalite', 'quartz' and 'tridymite'. A total number of 18 published documents with the information of crystalline silica level in air or bulk samples were selected and used to estimate retrospective exposures to crystalline silica. Weighted arithmetic mean(WAM) calculated across studies was summarized by industry type. Industries were classified according to Korea Standard Industrial Classification(KSIC) using information provided in the literature. Results: A total of 2,131 individual air sampling data measured from 1987 to 2012 were compiled. Compiled individual measurement data consisted of 827 respirable crystalline silica (RCS), 31 total crystalline silica(TCS), 24 crystalline silica(CS), 778 respirable dust(RD) and 471 total dust(TD). Most of RCS measurements(68.9%) were collected from 'cast of metals(KSIC 243)'. Comparing industry types, 'mining coal and lignite(KISC 051)' showed the highest WAM concentration of RCS, $0.14mg/m^3$, followed by $0.11mg/m^3$ of 'manufacture of other non-metallic mineral products(KSIC 239)', $0.108mg/m^3$ of 'manufacture of ceramic ware(KSIC 232)', $0.098mg/m^3$ of 'heavy construction(KSIC 412)' and $0.062mg/m^3$ of 'cast of metals(KSIC 243)'. In terms of crystalline silica contents in airborne dust, 'manufacture of other non-metallic mineral products(KSIC 239)' showed the highest value of 7.3%(wt/wt), followed by 6.8% of 'manufacture of ceramic ware(KSIC 232)', 5.8% of 'mining of iron ores(KSIC 061)', 4.9% of 'cast of metals(KSIC 243)' and 4.5% of 'heavy construction(KSIC 412)'. WAM concentrations of RCS had no consistent trends over time from 1994 ($0.26mg/m^3$) to 2012 ($0.12mg/m^3$). Conclusion: The data set related RCS exposure level by industries can be used to determine not only the possibility of retrospective exposure to RCS, but also to evaluate the level of quantitative retrospective exposure to RCS.

타일 제조 작업자의 결정형 유리규산 노출평가 사례 (Exposure Assessment of Tile Manufacturing Workers to Crystalline Silica)

  • 차원석;김은영;김대호
    • 한국산업보건학회지
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    • 제33권3호
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    • pp.291-297
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    • 2023
  • Objectives: An epidemiological investigation was requested for a worker who developed COPD and IPF after long-term molding and firing at a domestic tile manufacturing site. We would like to share the results of the exposure assessment and the estimation of past work. Methods: The content of crystalline silica in four raw materials was analyzed, and the respirable fraction of crystalline silica and dust generated in the air from molding and firing workers and other processes were measured. The measurement and analysis method referred to the NIOSH method. Results: The crystalline silica content of the raw material was 24~47%. The concentration of crystalline silica in the molding and firing process workers and the surrounding area was at the level of the exposure standards set by the Ministry of Employment and Labor and ACGIH, and the respirable and total dust exposure levels were generally low. The crystalline silica concentration of the area samples measured to estimate past work was about twice as high as the exposure standard of the Ministry of Employment and Labor (0.05 mg/m3), and the exposure levels of respirable dust were also quite high at 0.903 and 1.332 mg/m3. Conclusions: It was confirmed that tile molding and firing workers are currently exposed to a fairly high level of crystalline silica, and a high level is also confirmed in area samples to estimate past work. In the past, it is judged that the level of exposure would have been much higher due to differences in production volume, working method, presence/absence of local ventilation facilities, and process layout. When working in such a working environment for a long time, respiratory diseases such as lung cancer, COPD, and IPF can occur.

국내 일부 채석장 작업자들의 분진 및 결정형 유리규산 노출평가 사례 (Assessing Dust and Crystalline Silica Exposures among Workers in Some Quarries in Korea)

  • 차원석;김은영;최성원;김미연
    • 한국산업보건학회지
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    • 제33권3호
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    • pp.284-290
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    • 2023
  • Objectives: Work environment assessments were conducted to investigate epidemiologically several cases of lung cancer and COPD (chronic obstructive pulmonary disease) among workers in domestic quarries. Methods: We visited three quarries in South Korea where an epidemiological investigation was requested and measured total dust, respirable dust, and crystalline silica on rock drilling workers (4 people) and rock chipping workers (13 people). Measurement and analysis were conducted according to NIOSH (National Institute for Occupational Safety & Health) method 0500, NIOSH method 0600 for respirable dust, and NIOSH method 7500 for crystalline silica. Results: Among rock drilling workers the AMs (arithmetic mean) of total dust concentrations, respirable dust concentrations, and crystalline silica concentrations were 3.462 mg/m3 (range: 0.764~6.085 mg/m3), 0.613 mg/m3 (range: 0.153~1.251 mg/m3), and 0.105 mg/m3 (range: 0.012~0.228 mg/m3), respectively. Among rock chipping workers, the AMs of total dust concentrations, respirable dust concentrations, and crystalline silica concentrations were 2.446 mg/m3 (range: 0.156~8.494 mg/m3), 0.488 mg/m3 (range: 0.028~1.536 mg/m3), and 0.099 mg/m3 (range: 0.004~0.274 mg/m3), respectively. Conclusions: Although it cannot be said that the dust concentrations were high for both rock drilling workers and rock chipping workers, the concentrations of crystalline silica were found to be high. If such work is performed for a long period of time, diseases such as lung cancer and COPD may occur, so the work environment needs to be improved.

결정성 실리카/질화 알루미늄 혼합충진에 따른 EMC의 물성 연구 (The study on the properties of binary mixture(crystalline silica/AIN) filled EMC(Epoxy Molding Compounds))

  • 김원호;홍용우;배종우;황영훈;김부웅
    • 마이크로전자및패키징학회지
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    • 제6권4호
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    • pp.41-48
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    • 1999
  • 실리카는 에폭시를 기지재로 하는 전자봉지재의 충진제로써 널리 사용되고 있는 재료이나 이의 낮은 방열성으로 인해 고방열성을 요구하는 부분에는 적용이 어렵다. 충진제 입자들의 지름비를 조합함으로써 최대충진 밀도를 높혀 고충진을 가능하게 하며 유동성도 향상된다는 점을 고려하여 높은 유동성을 가진 결정성 실리카(crystalline silica)를 큰 입자로 하고, 높은 열전도도와 낮은 열팽창계수를 가지지만 상대적으로 고각인 AlN을 작은 입자로 선정하여 혼합충진에 따른 EMC의 물성을 평가하였다. 실리카/AlN의 혼합비에 따른 EMC의 물성측정 결과, AlN의 투입분율을 0.3으로 하였을 때가 AlN의 투입에 따른 물성향상 효과가 가장 뛰어남을 확인 할 수 있었다. 따라서 AlN을 결정성 실리카와 최대 충진밀도에서 혼합하여 EMC에 적용할 경우에, 유동성의 저하없이 AlN의 소량투입만으로 뚜렷한 물성향상 효과를 얻을 수 있음을 확인할 수 있었다.

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규조토 분진 측정 및 분석 방법의 비교에 관한 연구 (A Study on Evaluation for Sampling and Analytical Methods of Diatomaceous Earth Dust)

  • 임현술;김지용;정희경
    • 한국산업보건학회지
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    • 제5권2호
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    • pp.212-225
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    • 1995
  • This study was performed in a diatomite factory located at Pohang City, Kyeongsangbuk-Do. The major objectives were to evaluate sampling and analytical methods of diatomaceous earth dust. Concentrations of total and respirable diatomaceous earth dust were measured. Size distribution of dust was analyzed by a personal cascade impactor and the particle size analyzer which is an application of multiple diffraction method. Also crystalline silica in respirable and total dust samples was analyzed quantitatively by X-ray diffraction and Fourie Transform Infrared Spectroscopy(FTIR). The results were as follows: The airborne total and respirable dust concentrations, particle size distribution, and cristalline silica(quartz) concentrations showed approximately a log-normal distribution. The means of totaldust concentrations at flour maufacturing, fire brick grinding and packaging processes exceeded the Korean and American Conference of Governmental Industrial Hygienists standards, $10mg/m^3$. The size distribution of diatomaceous earth dust was log-normal and identified as the rspirable particle mass and thoracic particle mass. The crystalline silica in respirable and total dust samples was identified to quartz and contained about 10 % in those samples. Finally, it is necessary to study the applicability of multiple diffraction for particle size distribution to compare the ACGIH's size selective sampling with other materials containing crystalline silica. Also, advanced quantitative study to X-ray diffraction and FTIR methods shoud be carried out 10 verify general and specific characteristics for respirable crystalline silica.

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Induction of Functional Changes of Dendritic Cells by Silica Nanoparticles

  • Kang, Kyeong-Ah;Lim, Jong-Seok
    • IMMUNE NETWORK
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    • 제12권3호
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    • pp.104-112
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    • 2012
  • Silica is one of the most abundant compounds found in nature. Immoderate exposure to crystalline silica has been linked to pulmonary disease and crystalline silica has been classified as a Group I carcinogen. Ultrafine (diameter <100 nm) silica particles may have different toxicological properties compared to larger particles. We evaluated the effect of ultrafine silica nanoparticles on mouse bone marrow-derived dendritic cells (BMDC) and murine dendritic cell line, DC2.4. The exposure of dendritic cells (DCs) to ultrafine silica nanoparticles showed a decrease in cell viability and an induction of cell death in size- and concentration-dependent manners. In addition, in order to examine the phenotypic changes of DCs following co-culture with silica nanoparticles, we added each sized-silica nanoparticle along with GM-CSF and IL-4 during and after DC differentiation. Expression of CD11c, a typical DC marker, and multiple surface molecules such as CD54, CD80, CD86, MHC class II, was changed by silica nanoparticles in a size-dependent manner. We also found that silica nanoparticles affect inflammatory response in DCs in vitro and in vivo. Finally, we found that p38 and NF-${\kappa}B$ activation may be critical for the inflammatory response by silica nanoparticles. Our data demonstrate that ultrafine silica nanoparticles have cytotoxic effects on dendritic cells and immune modulation effects in vitro and in vivo.

페인트 제조 작업자의 6가 크롬 및 실리카 노출평가와 호흡보호구 밀착도 검사 사례 (Case study of Hexavalent Chromium and Silica Exposure Assessment and Respiratory Fit-test for Paint Manufacturing Worker)

  • 이현석;김부욱
    • 한국산업보건학회지
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    • 제31권4호
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    • pp.295-303
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    • 2021
  • Objective: Paint manufacturing industry workers are exposed to various lung cancer carcinogenic substances including hexavalent chromium and crystalline silica. Studies have been conducted on lung cancer in Paint manufacturing industry workers and the concentration of hexavalent chromium in paint industry; however, the concentration of crystalline silica and hexavalent chromium and cases of lung cancer in a single Paint factory has never been reported in Korea. Methods: To determine whether the cancer was related to his work environment, we assessed the level of exposure to carcinogens during pouring and mixing talc and pigment. In addition, a mask fit test was performed for the worker. Results: Analysis of talc and silica bulk powder materials showed that crystalline silica (quartz) was 5% in talc and 100% in silica. The green and yellow pigments contained 87% and 92% of lead chromate, respectively. Our quantitative analysis of pigment powder samples showed that the hexavalent chromium contents quantified in the green and yellow pigment samples were 87% and 92%, respectively. In order to estimate his exposure level of hexavalent chromium, we measured a personal exposure level of hexavalent chromium for a worker in accordance with the National Institute for Occupational Safety and Health #7605 method. The results showed that the worker was exposed to the high level of hexavalent chromium (0.033 mg m-3). In addition, the talc powder also contained 5% quartz, and the worker's exposure level to respirable quartz exceeded OEL. As a result of the respiratory protection fit test for workers, the overall Fit Factor was '15' when wearing a second-grade mask and '25' when wearing a first-grade mask, significantly lower than the US Occupational Safety and Health Agency (OSHA) pass value of "100". Conclusion: Workers who pouring and mixing powder materials such as talc or colored pigments in paint manufacturing company may be exposed to high concentrations of carcinogenic substances. These findings indicate that it is necessary to local ventilation system inspection, safety and health education for employers and workers, and periodically monitoring and manage the working environment.

제조업체에서 발생하는 호흡성분진중 XRD와 FTIR를 이용한 결정형유리규산 농도의 분석 제2부 : 요업, 석재, 콘크리트, 유리, 연탄 및 기타사업장 (Analysis of Quartz Contents by XRD and FTIR in Respirable Dust from Various Manufacturing Industries Part 2 - Ceramics, Stone, Concrete, Glass and Briquets, etc.)

  • 김현욱;피영규;노영만;원정일
    • 한국산업보건학회지
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    • 제9권1호
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    • pp.99-111
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    • 1999
  • The purpose of this study was to evaluate crystalline silica contents in airborne respirable dusts from various manufacturing industries and to compare analytical ability of two different methods of quantifying crystalline silica, X-ray diffraction(XRD) and Fourie transform infrared spectroscopy(FTIR). Various manufacturing industries with a history of having pneumoconiosis cases and also known to generate dusts containing crystalline silica were investigated. These industries include: ceramics, brick, concrete, and abrasive material etc. The personal respirable dust samples were collected using l0mm, Dorr-Oliver nylon cyclone equipped with 37mm, $5{\mu}m$ pore size. polyvinylchloride (PVC) filters as collection media. All samples were weighed before and after sampling and were pretreated according to the NIOSH sampling and analytical methods 7500, and 7602 for dust collection and quartz analysis. A total of 48 samples were collected from these industries. Initial analyses of these samples showed log-normal distributions for dust and quartz concentrations. Some results from ceramics and stone exceeded current Korean Occupational Exposure Limits. The average concentrations of personal respirable dust by cyclone were 0.43, 0.24, 0.26, 0.42, 0.53 and $0.29mg/m^3$ in ceramics, stone, concrete, glass, briquets, and others, respectively. A comparison of performance of two analytical methods for quantifying crystalline silica was performed using data from ceramics. The results showed that no significant difference was found between two methods for ceramics. The mean crystalline silica contents determined by XRD were 3.41 % of samples from briquets and 7.18 % from ceramics and were 2.58 % from concrete and 10.33 % from ceramics by FTIR. For crystalline silica analysis, two analytical techniques were highly correlated with $r^2=0.81$ from ceramics. Both cristobalite and tridymite were not detected by XRD and FTIR.

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결정형 산화규소의 표준시료 확보방안에 대한 연구 (A Study on Developing Reliable Standard Samples of Crystalline Silica)

  • 황은송;이은지;박해동
    • 한국산업보건학회지
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    • 제34권3호
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    • pp.247-253
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    • 2024
  • Objectives: The purpose of this study is to establish a method for the production of standard samples of crystalline silica and to assess its feasibility for the future application in non-mandatory quality control. Methods: We dispersed crystalline silica in 2-propanol to prepare a 1 mg/mL dispersion solution. Between 50-200 uL of the dispersion solution was taken with a pipette, injected onto PVC filters, air-dried, and used as samples. The variation and homogeneity of the quartz concentrations were confirmed by FTIR analysis. Analytical proficiency testing was conducted across 30 voluntary participants. Results: The coefficient of variation was lower for samples prepared using supernatant (settled for 16 hours) compared to those made with dispersion solution. The contamination level after using the pipette tip one to five times was 8.13-9.89% of the solution's concentration. Homogeneity was confirmed within the concentration of 0.0223-0.0431 mg/mL, but it was not at the higher concentration of 0.0553 mg/mL. In the analytical proficiency testing, the coefficient of variation for each level ranged from 24.6% to 28.3%, with a compliance rate of 90.0% to 96.7%. Conclusions: This study was conducted to produce standard samples of crystalline silica. The homogeneity of the samples was confirmed at low concentrations. However, further investigations on the applicability of wider range of concentrations are needed.