• 분석과학
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• 제18권5호
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• pp.419-424
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• 2005

최근 환경 잔류성 유기오염 물질과 내분비계 장애물질로 지정된 다이옥신은 가장 중요한 환경 물질로 취급되어 인체위해성 평가, 배출 오염원 측정 및 분석 방법, 저감대책, 환경에의 농도 및 영향 평가를 위한 다양한 연구가 수행되고 있다. 폐기물 소각 등 모든 연소과정에서 주로 생성된 후 대기 순환 등을 통하여 환경 중에 확산된 다이옥신 등은 토양에 축적된다. 본 연구에서는 산업 폐기물 소각장 배출 가스, 생활 쓰레기 소각장 배출 가스 및 대기 그리고 토양의 시료로부터 다이옥신의 이성질체 분포에 대한 상관성을 비교하였다. PCDDs와 PCDFs를 OCDD를 기준으로 하여 그 비율에 기초하여 곡선을 작성하여 그 형태로부터 유사성을 비교한 결과 산업 폐기물 소각장 배출 가스와 대기 중에서의 이성질체 분포 곡률과 비율이 거의 일치함을 볼 수 있다. PCDDs와 PCDFs의 결과를 비교하였을 때 서로 유사한 곡률과 비율에 대한 결론을 나타내었으며 따라서 환경 중에 노출되는 다이옥신은 생활 쓰레기 소각장 배출 가스보다는 산업 폐기물 소각장 배출가스에 좀 더 의존적임을 알 수 있었다. 토양 시료의 경우 농약 등 다른 오염원의 가능성 및 자연 분해 정도를 배제할 수는 없지만 곡률의 형태는 배출가스들과 유사함을 보여 토양 오염 또한 소각장 배출 가스들에 기인함을 유추할 수 있었다.

• 환경생물
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• 제29권4호
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• pp.373-378
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• 2011

Our aim was to investigate the genotoxicity of ambient air in the Krak$\acute{o}$w area after Fukushima Nuclear Power Plant (NPP) accident and compare with results from Chernobyl fallout. For the detection of ambient air genotoxicity the technique for screening gene mutation frequency in somatic cells of the $Tradescantia$ stamen hairs ($Trad$-SH assay) was used. Since 11th of March 2011 (Fukushima NPP accident), several pots containing at least 15 shoots of bioindicating plants were exposed to ambient air at 2 sites in the Krak$\acute{o}$w surrounding area, one in the city center, and about 100 pots in a control site (in the glasshouse of the Institute of Nuclear Physics) Continuous screening of mutations was performed. Progenies of 371,090 cells exposed were analyzed. Mutation frequency obtained in the first 10 days has shown a mean control level (GMF*100=$0.06{\pm}0.01$). At scoring period related to influence of a potential Fukushima fallout, a significant increase of gene mutation frequencies above the control level was observed at each site in the range, 0.10~0.33 depending on the location, (mean value for all sites GMF*100=$0.19{\pm}0.05$) that was associated with a strong expression of toxic effects. In the reported studies following the Chernobyl NPP accident monitoring $in$ $situ$ of the ambient air genotoxicity was performed in the period since April $29^{th}$ till June $3^{rd}$ 1986 also with Trad-SH bioindicator. In general, mutation frequency increases due to Chernobyl fallout(GMF*100=$0.43{\pm}0.02$) were corresponding to fluctuation of radioactivity in the air reported from physical measures, and to published reports about increase in chromosome aberration levels. Although, recent data obtained from monitoring of the ambient air quality in the Krak$\acute{o}$w and surroundings are lower when compared to results reported after Chernobyl NPP accident, though results express a significant increase above the control level and also are corresponding with increased air radioactivity reported from physical measurements. Statistically significant in comparison to control increase in gene mutation rates and more prolonged than that after Chernobyl fallout increase of GMF was observed during the period following the Fukushima NPP failure.

• 한국전기전자재료학회논문지
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• 제18권6호
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• pp.554-559
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• 2005

Ni/Cr thin film is very interesting material as thin film resistors, filaments, and humidity sensors because their relatively large resistivity, more resistant to oxidation and a low temperature coefficient of resistance (TCR). These interesting properties of Ni/Cr thin films are dependent upon the preparation conditions including the deposition environment and subsequent annealing treatments. Ni/Cr thin films of 250 nm were deposited by DC magnetron sputtering on $Al_2O_3/Si$ substrate with 2-inch Ni/Cr (80/20) alloy target at room temperature for 45 minutes. Annealing treatments were performed at $400^{\circ}C,\;500^{\circ}C,\;and\;600^{\circ}C$ for 6 hours in air or $H_2$ ambient, respectively. The clear crystal boundaries without crystal growth and the densification were accomplished when the pores were disappeared in air ambient. Most of surface was oxidic including NiO, $Ni_2O_3$ and $Cr_xO_y$(x=1,2, y=2,3) after annealing in air ambient. The crystal growth in $H_2$ ambient was formed and stabilized by combination with each other due to the suppression of oxidized substance on film surface. Most oxidic Ni was restored when the oxidic Cr was present due to its stability in high-temperature $H_2$ ambient.

• 환경기술인
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• 통권158호
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• pp.12-15
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• 1999

• Journal of Biosystems Engineering
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• 제23권3호
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• pp.229-244
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• 1998

This study was performed to determine proper fan and heater management schemes for natural air drying of rough rice in round steel bin with stirring device under Korean weather conditions. A computer simulation model was developed to predict moisture content changes, energy requirements, and drymatter losses during drying of rough rice by natural air. Drying test was conducted to validate the simulation model using round steel bin of holding capacity of 300ton at Rice Processing Complex in Jincheon. The bin was filled with rough rice every day and mixing by stirring device. Moisture contents, ambient air temperatures, relative humidities, static pressures in plenum chamber in the bin, airflow rates, and electrical and fuel energy were measured. Relative errors of moisture content changes predicted by the simulation model were below 5ft, and relative errors of final moisture content, final grain weight, required energy ranged from 0.9% to 6%. These not levels indicated that the simulation model can satisfactorily predict the performance factors of natural air drying system such as drying rates and energr consumptions comparing error level of 10% to 15% in other drying simulation models generally used in dryer desists. Twelve different fan and heater management schemes were evaluated using the computer simulation model based on three hourly weather data from Suweon for the period of 1952-1994. The best management schemes were selected comparing the drymatter losses, required drying times, required energy consumptions. Operating fan without heating only when ambient relative humidity was below 85% or 90% appeared to be the most effective method of In operation in favorable drying weather. Under adverse drying climates or to reduce required drying time, operating fan continuously, and heating air with $1.5^{\circ}C$ temperature rise only when ambient relative humidity was over 85% appeared to be the most suitable method.

• 한국분말재료학회지
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• 제23권2호
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• pp.136-142
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• 2016

As precursors of cathode materials for lithium ion batteries, $Ni_{1/3}Co_{1/3}Mn_{1/3}(OH)_2$ powders are prepared in a continuously stirred tank reactor via a co-precipitation reaction between aqueous metal sulfates and NaOH in the presence of $NH_4OH$ in air or nitrogen ambient. Calcination of the precursors with $Li_2CO_3$ for 8 h at $1,000^{\circ}C$ in air produces dense spherical cathode materials. The precursors and final powders are characterized by X-ray diffraction (XRD), scanning electron microscopy, particle size analysis, tap density measurement, and thermal gravimetric analysis. The precursor powders obtained in air or nitrogen ambient show XRD patterns identified as $Ni_{1/3}Co_{1/3}Mn_{1/3}(OH)_2$. Regardless of the atmosphere, the final powders exhibit the XRD patterns of $LiNi_{1/3}Co_{1/3}Mn_{1/3}O_2$ (NCM). The precursor powders obtained in air have larger particle size and lower tap density than those obtained in nitrogen ambient. NCM powders show similar tendencies in terms of particle size and tap density. Electrochemical characterization is performed after fabricating a coin cell using NCM as the cathode and Li metal as the anode. The NCM powders from the precursors obtained in air and those from the precursors obtained in nitrogen have similar initial charge/discharge capacities and cycle life. In conclusion, the powders co-precipitated in air can be utilized as precursor materials, replacing those synthesized in the presence of nitrogen injection, which is the usual industrial practice.

• Journal of Preventive Medicine and Public Health
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• 제51권6호
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• pp.265-274
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• 2018

Objectives: A positive association between air pollution and both the incidence and prevalence of diabetes mellitus (DM) has been reported in some epidemiologic and animal studies, but little research has evaluated the relationship between air pollution and diabetic coma. Diabetic coma is an acute complication of DM caused by diabetic ketoacidosis or hyperosmolar hyperglycemic state, which is characterized by extreme hyperglycemia accompanied by coma. We conducted a time-series study with a generalized additive model using a distributed-lag non-linear model to assess the association between ambient air pollution (particulate matter less than $10{\mu}m$ in aerodynamic diameter, nitrogen dioxide [$NO_2$], sulfur dioxide, carbon monoxide, and ozone) and emergency department (ED) visits for DM with coma in Seoul, Korea from 2005 to 2009. Methods: The ED data and medical records from the 3 years previous to each diabetic coma event were obtained from the Health Insurance Review and Assessment Service to examine the relationship with air pollutants. Results: Overall, the adjusted relative risks (RRs) for an interquartile range (IQR) increment of $NO_2$ was statistically significant at lag 1 (RR, 1.125; 95% confidence interval [CI], 1.039 to 1.219) in a single-lag model and both lag 0-1 (RR, 1.120; 95% CI, 1.028 to 1.219) and lag 0-3 (RR, 1.092; 95% CI, 1.005 to 1.186) in a cumulative-lag model. In a subgroup analysis, significant positive RRs were found for females for per-IQR increments of $NO_2$ at cumulative lag 0-3 (RR, 1.149; 95% CI, 1.022 to 1.291). Conclusions: The results of our study suggest that ambient air pollution, specifically $NO_2$, is associated with ED visits for diabetic coma.

• Journal of Biosystems Engineering
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• 제37권3호
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• pp.184-191
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• 2012

Purpose: This study was conducted to investigate the storage and quality characteristics of brown rice under the low temperature warehouse conditions using ambient cold air in the winter. Methods: This new technique maintains rough rice warehouse temperature below $15^{\circ}C$ without cooling operation until the end of May. Four hundred tons of rough rice were stored in the low temperature grain warehouse, and were aerated from the top to the bottom using ambient cold air in February. The quality of rough rice was evaluated from February through October. Results: The results were as followings. Moisture contents of rough rice in the low temperature storage had decreased less than the ordinary temperature storage. Cracked rate of brown rice in the ordinary temperature storage and low temperature storage increased by 4~10.8% and 1.6~7.2%, respectively. The germination rate of rough rice under the ordinary and the low temperature warehouse decreased by 15.0~25.0% and 1.7~8.0%, respectively. The acid value of brown rice under the ordinary and the low temperature warehouse increased by 3.67~6.72 KOH mg/100g and 3.08~4.08 KOH mg/100g, respectively. Conclusions: The result indicates that low temperature storage using ambient winter air showed better maintaining germination of rice, less change of physiological activities and cracked kernel, and better maintaining of rice quality, comparing the ordinary temperature storage.

• 대한환경공학회지
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• 제31권4호
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• pp.294-299
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• 2009

다이옥신의 대기 중 오염수준 및 거동을 조사하기 위해 청주시를 대상으로 3지점(공단, 주거/상업 및 농촌지역)에서 2008년 겨울철, 봄철, 및 여름철에 가스상과 입자상으로 나누어 시료를 채취하였다. 채취된 9개 시료의 대기 중 17개 다이옥신 이성질체의 농도범위는 0.73~2.48(평균 1.41) pg/$m^3$으로 검출되었으며, WHO 2005 TEQ 농도범위는 0.007~0.122(평균 0.051) pg TEQ/$m^3$으로 조사되었다. 이들 농도는 우리나라 다른 도시대기의 농도(불검출~2.149 pg TEQ/m3 )와 유사하거나 낮은 수준을 나타내었다. 대기 중 다이옥신은 대부분이 입자상태로 존재하고 있었으며(총 농도의 54~98%), 시료채취 시기나 지점에 관계없이 유사한 이 성질체 패턴을 나타내었다. 이성질체 분포 비교 및 통계적 해석결과, 청주시 대기 중 다이옥신은 특정한 오염원에 의한 영향은 미비하며 일반적인 연소공정에 의한 영향을 받고 있는 것으로 판단된다.

• 한국환경보건학회지
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• 제24권2호
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• pp.110-117
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• 1998

This study was carried out to investigate the concentrations of TSP, Pb, Zn and Fe in ambient air adjacent to the heavy traffic road side in Seoul from October 1 to October 31, 1997. The results were as follows 1. The concentrations of TSP were 260 $\mu g/m^3$, 184 $\mu g/m^3$, 147 $\mu g/m^3$ in Chongro, Chungkechun and Kangnam-terminal, respectively. The concentration of TSP was correlated with the traffic volume of the sampling sites (r=0.77). 2. The concentrations of Pb were 638 ng/m$^3$, 335 ng/m$^3$, 233 ng/m$^3$ in Chungkechun, Kangnam-terminal and Chongro, respectively. The concentration of Pb was correlated with the Truck (over 1.4 ton) volume of the sampling sites (r=0.71). The Pb contents among these sites were significantly different (p < 0.05). 3. The concentrations of Zn were 535 ng/m$^3$, 461 ng/m$^3$, 439 ng/m$^3$ in Chongro, Kangnam-terminal and Chungkechun, respectively. The concentration of Zn was badly correlated with the traffic volume of the sampling sites (r=0.23). 4. The concentrations of Fe were 5.32 $\mu g/m^3$, 4.51 $\mu g/m^3$ and 3.18 $\mu g/m^3$ in Chongro, Kangnam-terminal and Chungkechun, respectively. The concentration of Fe was correlated with the traffic volume of the sampling sites (r=0.83). The Fe contents among these sites were significantly different (p < 0.05). 5. The concentrations of TSP, Pb, Zn, Fe investigated didn't exceed the Korean Ambient Air Quality Standards, but more researches in relation to these will be required in considering people working in these sites suffered from cough, asthma and chronic headache.