• 자원환경지질
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• 제36권6호
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• pp.481-490
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• 2003

본 연구는 국내 폐금은광산 지역에서의 광산활동의 의한 (1)계의 물시료 및 퇴적물 내의 As의 오염 수준, (2)오염된 자연수 중에 존재하는 As의 화학종의 조사, (3)수계내 As의 건/우기에 따른 계절적 변화, (4)연속추출분석법을 이용한 퇴적물내의 As의 화학적 형태연구를 목적으로 한다. 본 연구를 위하여 국ㆍ내 6개의 폐금은광산 지역에 대하여 갱내수, 하천수 및 지하수 등의 자연수와 하강퇴적물을 채취하였다. 동일광산 갱내수의 As의 함량이 524${\mu}m$/L로 국내 광산폐수내 기준치(500 ${\mu}m$/L)를 초과하였으며, 하천수 역시 동일(63.7∼l17.6${\mu}m$/L) 구봉(56.1∼62.9${\mu}m$/L) 광산지역에서 부화되어 있었다. 연구지역내에서 음용수로 사용하고 있는 지하수내 비소의 함량은 동일, 옥동과 구봉광산에서 각각 11.3∼63.5${\mu}m$/L, 0.2∼68.9 ${\mu}m$/L과 2.0∼101.0${\mu}m$/L으로 일부 시료에서 국내 먹는 샘물 기준치(50${\mu}m$/L)를 초과하였다. 대부분의 수계에서 arsenate(As(V), $H_2AsO_4^-$)가 arsenite[As(III), $H_3AsO_3$]에 비해 우세한 존재형태이나 총As함량에 대한 arsenite(III)의 함량 비가 옥동광산지역의 하천수 시료에서 최고 95%까지 존재하고 있었으며 옥동과 동정광산 지역의 지하수에서는 70∼82%를 나타내었다. 수계내의 A저 계절적 변화의 관찰 결과, 동일광산지역의 수계에서 우기(9월 채취시료)에 비해 건기(4월 채취시료)에 상대적으로 부화된 양상을 명확히 보였다. 퇴적물에 대한 연속추출분석결과 As는 동정과 구봉광산의 시료에서 주로 비결정질 철수산화물과 공침전한 형태로 존재하고 있었으며(35.9∼40.5%) 이는 환원환경 하에서의 As의 재 용출에 의한 오염의 진행을 야기할 수 있다. 그러나, 동일 및 옥동 광산지역의 하강퇴적물은 주로 황화물 형태로 존재했다 (55.2∼83.4%).

• Applied Science and Convergence Technology
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• 제27권1호
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• pp.9-13
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• 2018

Samples of anodic oxide film used in semiconductor and display manufacturing processes were prepared at different electrolyte temperatures to investigate the corrosion resistance. The anodic oxide film was grown on aluminum alloy 6061 by using a sulfuric acid ($H_2SO_4$) electrolyte of 1.5 M at $0^{\circ}C$, $5^{\circ}C$, $10^{\circ}C$, $15^{\circ}C$, and $20^{\circ}C$. The insulating properties of the samples were evaluated by measuring the breakdown voltage, which gradually increased from 0.43 kV ($0^{\circ}C$) to 0.52 kV ($5^{\circ}C$), 1.02 kV ($10^{\circ}C$), and 1.46 kV ($15^{\circ}C$) as the electrolyte temperature was increased from $0^{\circ}C$ to $15^{\circ}C$, but then decreased to 1.24 kV ($20^{\circ}C$). To evaluate the erosion of the film by fluorine plasma, the plasma erosion and the contamination particles were measured. The plasma erosion was evaluated by measuring the breakdown voltage after exposing the film to $CF_4/O_2/Ar$ and $NF_3/O_2/Ar$ plasmas. With exposure to $CF_4/O_2/Ar$ plasma, the breakdown voltage of the film slightly decreased at $0^{\circ}C$, by 0.41 kV; however, the breakdown voltage significantly decreased at $20^{\circ}C$, by 0.83 kV. With exposure to $NF_3/O_2/Ar$ plasma, the breakdown voltage of the film slightly decreased at $0^{\circ}C$, by 0.38 kV; however, the breakdown voltage significantly decreased at $20^{\circ}C$, by 0. 77 kV. In addition, for the entire temperature range, the breakdown voltage decreased more when sample was exposed to $NF_3/O_2/Ar$ plasma than to $CF_4/O_2/Ar$ plasma. The decrease of the breakdown voltage was lower in the anodic oxide film samples that were grown slowly at lower temperatures. The rate of breakdown voltage decrease after exposure to fluorine plasma was highest at $20^{\circ}C$, indicating that the anodic oxide film was most vulnerable to erosion by fluorine plasma at that temperature. Contamination particles generated by exposure to the $CF_4/O_2/Ar$ and $NF_3/O_2/Ar$ plasmas were measured on a real-time basis. The number of contamination particles generated after the exposure to the respective plasmas was lower at $5^{\circ}C$ and higher at $0^{\circ}C$. In particular, for the entire temperature range, about five times more contamination particles were generated with exposure to $NF_3/O_2/Ar$ plasma than for exposure to $CF_4/O_2/Ar$ plasma. Observation of the surface of the anodic oxide film showed that the pore size and density of the non-treated film sample increased with the increase of the temperature. The change of the surface after exposure to fluorine plasma was greatest at $0^{\circ}C$. The generation of contamination particles by fluorine plasma exposure for the anodic oxide film prepared in the present study was different from that of previous aluminum anodic oxide films.

• 한국정보통신학회논문지
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• 제23권12호
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• pp.1535-1541
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• 2019

방사선 사고 지역 및 제염이 필요한 지역에서의 안전하고 신속한 제염작업을 진행하기 위해서는 방사선 오염원에 대한 다양한 정보 획득이 필요하다. 특히 방사선원의 정확한 위치와 분포 정보의 파악은 신속한 후속 조치 및 오염원 제거를 위해 반드시 필요하며, 작업자의 방사선 피폭을 최소화할 수 있다. 방사선원의 위치와 분포 정보를 획득하기 위해서는 방사선 분포 탐지 장치를 사용한다. 방사선 분포 탐지 장치의 경우 일반적으로 탐지 센서 부가 단일 센서로 구성되며, 단일 센서의 물리적 한계로 인해 탐지 범위가 제한되는 문제점이 있다. 본 논문에서는 방사선 오염 분포 영상화 장치에 사용되는 단일 센서의 탐지 감도 제어를 위하여 보정 검출기를 적용하였으며, 이를 통해 제한적이었던 선량률 탐지 범위를 향상하였다. 또한 감마선 조사 시험을 통해 방사선 분포 탐지 범위의 개선을 확인하였다.

• 한국식품위생안전성학회지
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• 제27권2호
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• pp.161-168
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• 2012

떡은 수분활성도, pH, 보관온도 등이 미생물 증식에 적합하고 구입 후 별도 조리과정 없이 그대로 섭취하는 식품으로 미생물학적 안전문제를 자주 야기하고 있다. 본 연구는 국내 유통 떡에 문제시되는 미생물학적 위해요인을 제조공정별로 파악하고 그 위생관리 개선방안을 도출하고자 하였다. 3가지 떡 (시루떡, 가래떡, 경단)을 선정하여 원료, 제조공정 및 제조환경에 대한 미생물 오염도 분석을 실시하였다. 8가지 원재료의 오염도 분석결과 일반세균 2.5~4.5, 대장균군 ND~1.9, 진균수 1.2~2.1, B. cereus 1.0~2.1 log CFU/g수준으로 검출되었으며 E. coli, S. aureus, C. perfringens는 검출되지 않았다. 떡의 제조공정별 오염도 분석결과 원료의 불림 분쇄 공정에서 일반세균, 대장균군, 진균, B. cereus의 오염도가 증가하나 증자 후 감소하여 완제품에서 일반세균은 2.2~3.7, 대장균군 ND~1.8 log CFU/g 수준으로 나타났다. 제조환경의 미생물학적 오염도 분석결과 전처리실의 쌀분쇄기, 냉각수조, 펀칭기 등의 설비에서 오염수준이 높게 나타났으며, 전처리실 작업자의 개인 위생이 미흡한 것으로 나타났다. 작업장 공기 오염도 분석결과 청결구역 3곳에서 일반세균 34~46, 대장균군 2.5~7.0, 진균수 14~30 $CFU/plate{\cdot}5min$ 검출되어 권장 낙하세균기준을 초과하는 것으로 나타났다. 본 연구결과 떡의 원재료 및 완제품의 미생물학적 오염수준은 안전하나 제조환경의 오염도는 문제시되는 것으로 나타나 제품의 교차오염 가능성을 내포하고 있는 것으로 사료된다. 따라서 제조 설비 및 표면시설에 대한 체계적인 세척 및 소독을 실시하여 미생물학적 위해를 감소하고 작업자 위생 관리 교육 프로그램을 선행하여 작업자 개인의 위생 수준 향상, 작업장 내 공기중의 미생물 관리가 함께 이루어지도록 하는 것이 필요한 것으로 여겨진다.

• 미생물학회지
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• 제16권2호
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• pp.71-78
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• 1978

Bacillus subtilis var. 816 was used for manufacturing fermented soybean which in turn is used as flavoring agent. Fermentation of soyebean or flat wheat was occasionally failed. It was elucidated that failure was due to the presence of bacteriophage. According to Hemphill and Whitely (1975), this bacteriphage might be belonged to the viulent phage group I as it is similar to SP82G, ${\phi}25$. In fact, the phenomena of the increase of moisture, disappenarance of mucin and existence of undersirable bacteria was attributed to the contamination of the above phage during the course of fermentation of soybean or flat wheat. Particularly disapparance of mucin was sufficiently correlated by the replication of the bacteriophage. The above phage can grow in the range of $30^{\circ}C\;to\;70^{\circ}C$. The optimum temperature was $40^{\circ}C{\sim}50^{\circ}C$. The optimum pH range was between pH 7.4 and pH 8.0. It is noticeable that staphylococci was replicating simultaneously with the phage. The head of 816 phage is hexagonal with a diameter of $10{\times}165{\sim}10{\times}240\;nm$. The end of the tail is enlaged. It has a size of 25 nm and this end areas are spreaded widely as fingers.

• 한국지하수토양환경학회지:지하수토양환경
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• 제24권6호
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• pp.26-32
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• 2019

An analysis of groundwater quality is significant for monitoring and managing water contamination and groundwater system. For the purpose of those, the geochemical characteristics of groundwater were studied over the concern for water quality, water type and origin of nitrate nitrogen. Total colony counts were detected in 11 out of 20 samples, and the average value was 31.73 CFU/ml. Range and average of NO₃-N concentrations were 0.9~24.0 mg/L and 8.3 mg/L. All groundwater types were found to be Ca²⁺-HCO₃^-. The range and average of NO₃-N were 0.2~17.4 mg/L and 8.7 mg/L, and those of δ¹⁵N were 1.7~8.9‰, and 5.0‰. Careful consideration is required for evaluating the origin of nitrogen when NO₃-N concentration is low. In general, noticeable difference between rockbed and alluvial water was not found. The ranges of nitrate origins by chemical fertilizer, livestock manure and domestic sewage, and natural soil were 29.6~76.4%, 14.2~58.9% and 2.6~7.0%, and the average values of those were 57.4%, 37.4%, and 5.3%, respectively. Origin of nitrate was affected by more chemical fertilizer than the other parameters. Rockbed water was more affected by chemical fertilizer than alluvial water.

• Current Optics and Photonics
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• 제1권3호
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• pp.247-251
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• 2017

In this study, an ultraviolet Raman spectrometer was designed and fabricated to detect chemical contamination on the ground. The region of the Raman spectrum that indicated the characteristics of the chemicals was $350-3800cm^{-1}$. To fabricate a Raman spectrometer operating in this range, the layout and angle of optical components of the spectrometer were designed using a grating equation. Experimental devices were configured to measure the Raman spectra of chemicals based on the fabricated Raman spectrometer. The wavenumber of the spectrometer was calibrated by measuring the Raman spectrum of polytetrafluoroethylene, $O_2$, and $N_2$. The spectral range of the spectrometer was measured to be 23.46 nm ($3442cm^{-1}$) with a resolution of 0.195 nm ($30.3cm^{-1}$) at 253.65 nm. After calibration, the main Raman peaks of cyclohexane, methanol, and acetonitrile were found to be similar to the references within a relative error of 0.55%.

• 한국환경보건학회지
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• 제26권2호
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• pp.116-121
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• 2000

This study was performed to investigate the heavy metal contents and distribution in bioorganisms from the estuary area of Mankyeong-Dongjin river. In paddy plant, the average contents of heavy metals were in order of Zn>Cu>Pb>Cr>Cd in all parts. Those of Cd, Cr, Pb and Cu were all highest in the leaf while lowest in the brown rice. The average content of Zn was almost similar in all parts. In the dried muscular parts of shellfish, the average contents of heavy metals were in the range of 1.06~1.95 mg/kg for Cd, 2.93~4.98 mg/kg for Cr, 0.90~1.17 mg/kg for Pb, 8.41~18.58 mg/kg for Cu and 29.81~67.31 for Zn, respectively, In fish(Acanthogobius hasta), the average contents of heavy metals in the dried body parts were in the range of 0.05~0.43 mg/kg for Cd, 0.65~4.59 mg/kg for Cr, 1.01~4.75 mg/kg for Pb and 1.34~4.19 mg/kg for Cu, with high accumulation in bone and head overally.

• Nuclear Engineering and Technology
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• 제54권10호
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• pp.3949-3956
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• 2022

Kori Unit 1 is planning a system decontamination project to reduce radiation exposure of decommissioning workers, prevent the spread of contamination and down-grade the level of classification of radioactive waste. The system decontamination range for Kori Unit 1 will be the entire primary system, including RCS, CVCS and RHRS. Some system design modifications are required for the system decontamination operation. In this paper, major system design modifications were evaluated based on the conditions that system restoration is needed after completion of system decontamination. The major system design modifications are CIDF connection location to system, system decontamination operating pressure control, RCP seal water injection and formation of letdown flow. It was evaluated that there was no negative effect on the system due to the system design modifications. However, as the RCP seal water is injected into the system in the oxidation process, the concentration of the oxidizing agent is diluted. Therefore, the oxidizing agent injection and system decontamination operation procedures should be developed to address the dilution effect of the oxidizing agent. The system design modifications dealt in this paper will be finally confirmed through on-site investigation in the future, and if necessary, the system design modifications will be re-evaluated.

• 반도체디스플레이기술학회지
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• 제18권4호
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• pp.62-68
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• 2019

The optoelectronic display units such as TFT-LCD or OLED require many thin optical plastic films and their mass manufacturing processes employ CO2 laser cutting of those thin films in a large quantity. However, laser film cutting could generate fume particles through melt shearing, vaporization, and chemical degradation and those particles could be of great concern for film surface contamination. In order to appreciate the fume particle dispersion behaviors in laser film cutting, this study relies on random particle simulations by probabilistic distributions of particle size, ejection velocity and angles coupled with Basset-Boussinesq-Oseen model of particle trajectory in low Reynolds number flows. Here, up to one million particles of random sampling have been tested to effectively show fume particles dispersed on the film surface. The computational results could show that particular range of fume particle size could easily disperse into the pixel region of processed optical films.