• 한국세라믹학회지
• /
• 제31권10호
• /
• pp.1218-1230
• /
• 1994

In manufacturing process of porous glass-ceramics by the filler method, the sintering behaviour of crystallizable glass powder mixed with various salts was studied and also the effects of precipitated crystal phases on the properties of porous glass-ceramics were investigated. Fine-grained crystallizable glass powder was homogeneously mixed with various slat having grain size 100~200 ${\mu}{\textrm}{m}$ and sintered for densification. After washing out the inorganic salt with distilled water, the porous sintered body was heat treated additionly for crystallization. The MgO-Al2O3-SiO2 base glass was used as crystallizable glass powder and the water soluble salts such as K2SO4 and MgSO4 were used as filler. When K2SO4 was used, leucite crystal phase was formed as a result of the ion exchange and porous glass-ceramics which exhibit high temperature resistance and high thermal expansion coefficient of 17$\times$10-6/$^{\circ}C$ could be obtained. On the contrary, when MgSO4 was used, only slight ion exchange is observed and $\mu$-cordierite and $\alpha$-cordierite crystal phases were formed and porous glass-ceramics which exhibit low thermal expansion coefficient schedule were determined with the results of DTA curves, thermal shrinkage curves and XRD patterns analysis. From DTA curves and thermal shrinkage curves, it was found that the sintering densification have been completed at the temperature range of exothermic peak for crystallization. The pore size distributions and pore diameters were measured by mercury porosimeter. The pore diameter of porous glass-ceramics was 10~15 ${\mu}{\textrm}{m}$ when 100~200${\mu}{\textrm}{m}$ grain size of K2SO4 was used and it was 25~30 ${\mu}{\textrm}{m}$ when the same grain size of MgSO4 was used. The porous glass-ceramics K2SO4 used shows bimodal pore size distribution and its porous skeleton structure was ascertained by SEM observation.

• Safety and Health at Work
• /
• 제2권3호
• /
• pp.229-235
• /
• 2011

Objectives: In this study, we summarized the External Quality Assessment Scheme (EQAS) for the biological monitoring of occupational exposure to toxic chemicals which started in 1995 and continued until a $31^{st}$ round robin in the spring of 2010. The program was performed twice per year until 2009, and this was changed to once a year since 2010. The objective of the program is to ensure the reliability of the data related to biological monitoring from analytical laboratories. Methods: One hundred and eighteen laboratories participated in the $31^{st}$ round robin. The program offers 5 items for inorganic analysis: lead in blood, cadmium in blood, manganese in blood, cadmium in urine, and mercury in urine. It also offers 10 items for organic analysis, including hippuric acid, methylhippuric acid, mandelic acid, phenylglyoxylic acid, N-methylformamide, N-methylacetamide, trichloroacetic acid, total trichloro-compounds, trans,trans-muconic acid, and 2,5-hexanedione in urine. Target values were determined by statistical analysis using consensus values. All the data, such as chromatograms and calibration curves, were reviewed by the committee. Results: The proficiency rate was below 70% prior to the first round robin and improved to over 90% for common items, such as PbB and HA, while those for other items still remained in the range of 60-90% and need to be improved up to 90%. Conclusion: The EQAS has taken a primary role in improving the reliability of analytical data. A total quality assurance scheme is suggested, including the validation of technical documentation for the whole analytical procedure.

• 한국건축시공학회지
• /
• 제18권3호
• /
• pp.305-312
• /
• 2018

This study is about the development of a non-sintered binder (NSB) which does not require a sintering process by using the industrial by-products Phosphogypsum (PG), Waste Lime (WL) and Granulated Blast Furnace Slag (GBFS). In this report, through SEM analysis of the NSB paste hardening body, micropore analysis of paste using the mercury press-in method and microstructure observation were executed to consider the influence of the formation of the pore structure and the distribution of pore volume on strength, and the following conclusions were reached. 1) Pore structure of NSB paste of early age is influenced by hydrate generation amount by GBFS and activator. 2) Through observing the internal microstructure of NSB binder paste, it was found that the strength expression at early age due to hydration reaction was achieved with a large amount of ettringite serving as the frame with C-S-H gel generated at the same time. It was confirmed that C-S-H gel wrapped around ettringite, and as time passed, the amount generated continually increased, and C-S-H gel tightly filled the pores of hardened paste, forming a dense network-type web structure. 3) For NSB-type cement, the degree of formation of gel pores below $10{\mu}m$ had a greater influence on strength improvement than simple pore reduction by charging capillary pores, and the pore size that had the greatest effect on strength was micropores with diameter below $10{\mu}m$.

• 농촌의학ㆍ지역보건
• /
• 제47권3호
• /
• pp.181-188
• /
• 2022

당뇨병 발생에는 생활습관이나 생활환경과 관련된 다양한 원인들이 있는데 최근 연구에서 중금속에 많이 노출된 사람에서 당뇨병 발생 및 당뇨병의 악화가 늘어났다는 역학적 연구가 많이 발표되고 있다. 이에 국내 대규모 철강공업단지를 가진 일개 도시 지역 주민을 대상으로 당화혈색소와 체내 중금속의 상관성을 파악하고자 하였다. 2008~2009년 연구대상 총 414명에 대한 설문조사와 생체시료를 채취하였다. 설문은 성별, 연령, 인구학적 특성, 흡연, 음주, 직업, 당뇨진단 유무 등의 항목으로 구성하였다. 혈액을 채취하여 HbA1c, 혈중 납 농도를 측정하였고, 소변을 채취하여 요중 카드뮴, 무기비소, 수은 농도를 측정하였다. HbA1c는 6.5%기준으로 미만군과 이상군으로 분류하였다. 각 중금속별 10분위수부터 90분위수 농도에 해당하는 기준으로 미만군과 이상군 등 두 군을 분류하였다. 당뇨관련검사 결과 HbA1c 6.5% 기준으로 이상군은 남자 14(9.9%)명, 여자 17(6.2%)명이었다. 혈중 납의 기하평균 농도는 2.48 (1.80) ㎍/dl, 요중 카드뮴의 기하평균농도는 1.20 (2.26) ㎍/g creatinine, 요중 무기비소의 기하평균농도는 12.08 (1.80) ㎍/g creatinine, 요중 수은의 기하평균농도는 1.63 (2.23) ㎍/g creatinine 이었다. 연령, 지역, 성별, 흡연으로 보정하였을때 요중 카드뮴 농도 30분위수 이상군이 미만군에 비하여 교차비 5.26(95% 신뢰구간 : 1.44~19.17)으로 유의하게 높았다. 납, 무기비소, 수은은 HbA1c(6.5% 기준) 변수와의 교차분석에서 유의한 분포 차이는 없었다. 여러 요인을 보정하고도 요중 카드뮴과 HbA1c의 유의한 양의 상관관계를 파악하였고, 특히 유의한 상관관계를 보인 요중 카드뮴 농도의 특정 컷오프 값을 찾아내어 이를 통해 우리나라에 적합한 생물학적 노출값 설정의 참고자료로 활용될 수 있다는 점에서 의의가 있다고 생각한다.

• 한국식품저장유통학회지
• /
• 제12권2호
• /
• pp.107-111
• /
• 2005

솔잎 열수 증류액 시료 자체의 음용수 적합성 여부와 향기성분 등 품질평가를 검토하였다. 음용수 평가 항목에 따라 총45종류의 성분을 측정하였으며 실험 모두에서 유해성분이 검출되지 않았다. 특히 인체에 유해한 비소 (As), 납 (Pb), 수은 (Hg) 및 카드뮴 (Cd)등과 같은 무기물이 검출되지 않았을 뿐만 아니라 기타의 성분도 음용수 기준치 내의 함량을 나타냄으로서 음용수로 사용하는데 적합한 것으로 평가되었다. 솔잎 열수 증류액의 향기성분에 대한 분석에서는 총34종류의 향기성분이 분석되었는데 우수한 향기성분으로서 fenchol, bomeol, $\beta-fenchyl$ alcohol 및 bomyl acetate의 경우는 각각 6.7, 13.1, 26.6 및 $16.2\%$ 함유되어 있었으며 대부분의 성분들이 alcohol이나 aldehyde 성분으로서 향기의 주요 성분들이었고 그 함유량도 비교적 높은 것으로 나타났다.

• 한국식품영양과학회지
• /
• 제13권1호
• /
• pp.22-26
• /
• 1984

최근(最近) 산업(産業)의 발전(發展)과 더불어 매연(煤煙)이나 발수(廢水)에서 배출(排出)되어 나오는 유기금속화합물유(有機金屬化合物類)는 더욱 더 증가(增加)하여, 직접, 간접으로 우려의 환경(環境)을 오염(汚染)시켜, 인명(人命), 가축(家畜), 식물(植物) 및 수자원(水資源)에까지 심각한 피해(被害)를 끼치고 있다. 그리하여 본실험(本實驗)에서는 금속화합물중(金屬化合物中) 특(特)히 수은(水銀)의 급여(給與)에 의한 급만성중독시(急慢性中毒時) 나타나는 체내(體內) 물질대사(物質代謝)의 영향(影響)에 관한 검사(檢討)를 목적(目的)으로 증류수에 $HgCl_2$를 용해(溶解)시켜 Hg의 함량(含量)을 달리한 후 (0, 5, 40, 200 ppm) 흰쥐에게 80일간(日間) 급여(給與)하였을 때 다음과 같은 결과(結果)를 얻었다. 1. 체중증가율(體重增加率)은 수은(水銀) 함량(含量)이 높아질수록 현저히 저하(低下)되었으며 또한 각종(各種) 장기(臟器)의 중량(重量)은 200 ppm 군(群)에서 전장기(全臟器)가 유의성(有意性) 있는 증가(增加)를 나타내었다. 2. 혈액(血液)의 Hematocrit치(値)와 혈청(血淸)중의 GOT, GPT는 별다른 변화(變化)를 보이지 않았으나 cholesterol은 200 ppm군(群)에서 유의(有意)하게 증가(增加)되었고 총단백질(總蛋白質)과 albumin함량(含量) 및 A/G ratio도 200 ppm군(群)에서 유의적(有意的)인 감소(滅少)를 관찰(觀祭)할 수 있었다. 3. 간장(肝臟) 및 신장(腎臟)중의 Hg, Ca, Mg의 함량(含量)은 수은(水銀) 함량(含量)이 증가(增加)할수록 현저히 높아졌으나 Cu와 Zn은 수은(水銀) 함량(合量)이 증가(增加)할수록 간장(肝臟)에서는 다소 감소(減少)하였으나 신장(腎臟)에서는 오히려 증가(增加)하였다.

• 콘크리트학회논문집
• /
• 제25권2호
• /
• pp.209-215
• /
• 2013

이 연구에서는 CaO-$Al_2O_3$계 급냉 제강슬래그(RCSS)의 물리 화학적 특성을 분석함으로써 친환경 무기 급결재로 활용방안을 모색하고자 하였다. RCSS의 성상은 섬유상과 구상으로 구별되었으며, 성상별로 CaO와 $Fe_2O_3$ 성분 함량이 반비례 경향을 나타냈다. 또한 CaO 함량이 낮아지고 $Fe_2O_3$ 함량이 증가함에 따라 강열감량은 (-)경향을 보였고 밀도는 증가하였다. 수은압입법에 의한 세공분포는 서냉 제강슬래그(SCSS)에 비해 매우 낮은 수치로 급냉에 의해 내부결함 및 미세기공률이 현저히 줄어든 것을 확인할 수 있었다. 급냉 제강슬래그를 구성하는 주요 광물을 분석하기 위해 XRD, f-CaO 정량, SEM-EDAX 분석을 실시한 결과에서 f-CaO의 존재는 관찰되지 않았으며, 구성성분이 주로 $C_{12}A_7$과 반응성 ${\beta}-C_2S$로 이루어져 있음을 확인할 수 있었다.

• 약학회지
• /
• 제57권1호
• /
• pp.8-17
• /
• 2013

The objective of this study is investigation of contamination levels and transfer rate of heavy metals and assessment of health risk effects in animal medicines. A total of sixteen items with 148 samples were obtained for this investigation from major herbal medicine producing areas and herbal markets from 2011 to 2012. Inductively coupled plasma mass spectrometer method was conducted for the quantitative analysis of Pb, Cd and As. In addition, the mercury analyzer system was conducted for that of Hg without sample digestion. The average contents of heavy metals in animal medicines were as follows : 1.55 mg/kg for Pb, 0.28 mg/kg for Cd, 0.70 mg/kg for As and 0.047 mg/kg for Hg respectively. The average contents of heavy metals in decoctions were as follows : 0.03 mg/kg for Pb, 0.01 mg/kg for Cd, 0.17 mg/kg for As and 0.003 mg/kg for Hg respectively. The average transfer rates of heavy metals from animal medicines to decoctions were 1.9% for Pb, 3.6% for Cd, 24.2% for As and 6.0% for Hg respectively. Cancer risks of animal medicines and decoctions through slope factor by ministry of environment republic korea and environmental protection agency was $1.36{\times}10^{-6}$ and $2.50{\times}10^{-8}$ for Pb and $7.46{\times}10^{-5}$ and $1.98{\times}10^{-5}$ for As (assuming that the total arsenic content was equal to the inorganic arsenic) respectively. The hazard index of heavy metals in animal medicines and decoctions was below recommended hazard index as 0.52 and 0.05 respectively. Taken together, cancer risks about Pb and hazard indexes of animal medicines and decoctions indicate that the majority of samples except for some samples with relative high contents of heavy metals were safe. But cancer risks about As of animal medicines indicate that the majority of samples were not relatively safe.

• 한국수산과학회지
• /
• 제52권5호
• /
• pp.452-460
• /
• 2019

Exposure to heavy metals through the consumption of contaminated seafood poses a health risk to humans. In Korea, seafood imports are increasing with consumption, with the largest increase in imported seafood coming from Russia. Peter the Great Bay and the Razdolnaya River are both major fisheries and protected areas under the Northwest Pacific Action Plan located near Vladivostok, Russia. This study analyzed heavy metal [cadmium (Cd), lead (Pb), total mercury (tHg), and total (tAs), and inorganic (iAs) arsenic] concentrations in shellfish and crustaceans collected from these areas. Except for iAs, the major toxic heavy metal concentrations of the samples met the national standards (Cd, 0.024-0.982 and 0.003-0.379 mg/kg; Pb, 0.021-1.533 and 0.002 mg/kg; tHg, 0.006-0.015 and 0.036-0.097 mg/kg). The tAs concentrations of three samples exceeded the Russian standard (5 mg/kg, wet weight), whereas the iAs concentrations were extremely low (ND-0.033 mg/kg). Compared with the provisional tolerable weekly intake (PTWI) of the Ministry of Food and Drug Safety and Joint FAO/WHO Expert Committee on Food Additives, the percentages of PTWI of Cd, Pb, and tHg were 0.239%, 0.001-0.049%, and 0.013-0.302%, respectively. These findings reveal that there is no potential health risk by heavy metals through the consumption of Russian seafood obtained in the surveyed areas.

• Fisheries and Aquatic Sciences
• /
• 제25권12호
• /
• pp.626-636
• /
• 2022

Shellfish are exoskeleton-bearing aquatic invertebrates that consume various organic and inorganic substances floating in seawater through filter feeding. Heavy metals are known as absorbed and accumulated in seawater. Some of the toxic heavy metals are highly accumulated in seawater, and exposure to them can cause a variety of risks to the human body. Since Koreans like to eat seafood, they are more likely to be exposed to contaminated seafood with heavy metals. In this study, nine types of heavy metals were analyzed on ten different shellfish species in the coastal area of South Korea. The risk assessment was also done on shellfish in which heavy metals were detected. Zinc (Zn) and copper (Cu) were identified at an average of 56.7 mg/kg (6.70 to 466 mg/kg) and 13.2 mg/kg (0.064 to 143 mg/kg), respectively. Lead (Pb) average of 0.208 mg/kg (0.000750 to 1.02 mg/kg), cadmium (Cd) average of 0.454 mg/kg (0.0388 to 1.56 mg/kg) and mercury (Hg) average of 0.0266 mg/kg (0.00548 to 0.174 mg/kg) were identified. Additionally, arsenic (As), chromium (Cr), nickel (Ni), and silver (Ag) were also identified as average concentrations of 4.02 (0.460 to 15.0 mg/kg), 0.167 (< limit of quantification [LOQ] to 0.820 mg/kg), 0.281 (< LOQ to 1.46 mg/kg), and 0.158 mg/kg (< LOQ to 1.15 mg/kg). The result indicates that the monitoring results of heavy metals in most shellfish satisfied the Korean standard. However, Pb and Cd have exceeded some foreign standards, such as the United States and the EU. The permissible human exposure calculated using the heavy metal intake and detection amount was lower than the Joint FAO/WHO Expert Committee on Food Additives human safety standard, and the risk of heavy metals from shellfish consumption was at an acceptable level.