• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2003년도 International Symposium
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• pp.111-124
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• 2003

기존의 오염물질을 제거하는 많은 화학적-물리적 정화 방법은 고비용과 오랜 시간을 요구하는 처리 과정 등의 단점을 갖고 있는 경우가 많았다. 따라서 흙과 수(水)환경내로 유입된 오염물질을 빠른 시간 내에 제거 할 수 있는 대안이 요구 되었다. 흙에 유출된 화합 물질 중 상당양은 흙에 의해 격리, 구속되고 이로 인해 일단 구속된 오염물질은 물과 유기 용매에 의해서도 잘 추출되지 않는 것으로 보고 되고 있다. 이러한 흙에 의한 오염물질의 비유동성(immobilization) 과정은 오염물질의 제거 기술의 대안으로 평가 될 수 있다. 기존 연구자들의 연구 결과, 화학적 혹은 물리적 반응 작용을 통해 오염물질을 흙을 구성하는 물질에 구속할 수 있음이 증명되었다. 이러한 과정 중 환경적 측면에서 볼 때, 화학적 반응이 더 우수하다 할 수 있다. 이는 강한 공유결합(covalent bonds)으로 연결될 경우 미생물의 활동이나 화학 처리로도 이를 분리하기 어렵기 때문이다. 리그닌(lignin) 분해에서 발생하는 휴믹(humic) 물질 등이 안정 된 화학적 연결을 통해 흙 매질 내에 오염물질과 결합하는 대표적 물질이다. 인위적으로 제조된 많은 화학물질은 자연적에서 발생하는 휴민산 발생원(humic acid precursors)과 닮았다. 따라서 화학물은 부식 과정(humifications process)동안 부식토(humus) 내로 병합(incorporate)되어 진다. 일단 이렇게 구성된 결합체는 생물체와 오염물질과의 반응을 방지하여 오염물질로 인한 생물체로의 독성을 감소시키는 역할을 하게 된다. 본 논문에서는 이러한 흙의 유기물(organic matter)와 오염물질과의 결합체에 대한 평가로서 다음의 항목에 대한 고찰이 이루어져야 함을 강조하였다. (a)결합체에서 생물체(biota)와의 반응에 의해 오염물질은 감소되는가\ulcorner (b) 모(parent) 화합물과 비교하여 복합체 생성물(complexed products)이 얼마나 덜 유독한가\ulcorner 그리고 (c)지하수 오염이 오염물질의 유동성 구속에 의해 얼마나 감소되는지\ulcorner

• 대한환경공학회지
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• 제22권5호
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• pp.949-957
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• 2000

본 연구는 페놀 분해균주인 P-99를 이용하여 슬러리상 반응기에서 페놀 또는 PNP (p-Nitrophenol)에 오염된 토양을 생물학적으로 복원시키는 방안을 모색하기 위해 수행되었다. 순수미생물에 의한 페놀의 분해는 혼합 미생물간의 경쟁적 상호작용을 배제시켜 활성슬러지의 지체시간보다 3배 정도 짧게 나타났다. 페놀 분해균주인 P-99는 300mg/L의 페놀을 26시간 안에 완전하게 분해하였으며, 페놀 1mg이 제거될 때 0.1457mg의 P-99 미생물이 생성되었다. PNP는 단일기질로 반응기내에 존재할 경우 페놀 분해균주인 P-99에 의한 분해는 일어나지 않았으나, 페놀에 유도된 경우 공대사 작용에 의해 효과적으로 분해할 수 있었으며, 이 때 PNP 분해에 있어서 성자기질인 페놀의 이용도는 0.027mg PNP/mg phenol이었다. 페놀과 PNP가 혼합기질로 반응기내에 존재할 경우 PNP의 농도가 증가할수록 미생물에 대한 저해작용이 증가되어 페놀의 분해속도가 감소하였으며, 슬러리상 반응기에서 미생물에 의한 페놀 및 PNP의 분해는 대상물질의 일부가 액상에서 토양의 표면으로 흡착되고 산소의 전달속도가 상승하여 액상에서 보다 2배 이상 가속화되었다.

• Journal of Radiation Protection and Research
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• 제44권4호
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• pp.128-148
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• 2019

Massive environmental monitoring has been conducted continuously since the Fukushima Daiichi Nuclear Power accident in March of 2011 by different monitoring methods that have different features together with migration studies of radiocesium in diverse environments. These results have clarified the characteristics of radiological environments and their temporal change around the Fukushima site. At three months after the accident, multiple radionuclides including radiostrontium and plutonium were detected in many locations; and it was confirmed that radiocesium was most important from the viewpoint of long-term exposure. Radiation levels around the Fukushima site have decreased greatly over time. The decreasing trend was found to change variously according to local conditions. The air dose rates in environments related to human living have decreased faster than expected from radioactive decay by a factor of 2-3 on average; those in pure forest have decreased more closely to physical decay. The main causes of air dose rate reduction were judged to be radioactive decay, movement of radiocesium in vertical and horizontal directions, and decontamination. Land-use categories and human activities have significantly affected the reduction tendency. Difference in the air dose rate reduction trends can be explained qualitatively according to the knowledge obtained in radiocesium migration studies; whereas, the quantitative explanation for individual sites is an important future challenge. The ecological half-lives of air dose rates have been evaluated by several researchers, and a short-term half-life within 1 year was commonly observed in the studies. An empirical model for predicting air dose rate distribution was developed based on statistical analysis of an extensive car-borne survey dataset, which enabled the prediction with confidence intervals. Different types of contamination maps were integrated to better quantify the spatial data. The obtained data were used for extended studies such as for identifying the main reactor that caused the contamination of arbitrary regions and developing standard procedures for environmental measurement and sampling. Annual external exposure doses for residents who intended to return to their homes were estimated as within a few millisieverts. Different forms of environmental data and knowledge have been provided for wide spectrum of people. Diverse aspects of lessons learned from the Fukushima accident, including practical ones, must be passed on to future generations.

• 한국산업보건학회지
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• 제30권1호
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• pp.28-38
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• 2020

Objectives: The purpose of this study is to identify the perceived problems of and suggest improvement measures for asbestos abatement companies in support of asbestos-related systems and policies. Methods: For this study a questionnaire was prepared consisting of current work (two questions), the contribution and necessity of a risk assessment system for asbestos abatement (two questions), and problems with and improvement measures for systems and policies (nine questions). The questionnaires were sent to 2,170 asbestos abatement companies and were returned by 83 companies (return rate = 3.8%). We conducted frequency analysis, ANOVA, and a Chi-squared test at the 5% significance level. Results: Asbestos abatement companies expressed difficulties with complying with wet work (43% of unenrolled managers), negative pressure enclosure (36% of all respondents), and installation and use of decontamination units (26% of all respondents) as stipulated in the relevant regulations. In addition, 43% of the respondents expressed concerns that the expertise of the company was not considered during bidding for asbestos abatement and hoped that an advantage (e.g., bid point) would be given to the upper grades for asbestos risk assessment (38%). Asbestos abatement companies generally rented and used negative pressure devices (including negative pressure recording devices) and suggested that periodic calibration (32%) is needed to ensure the performance of the rented equipment. Finally, the respondents asked for clear definitions for three situations specified in the Occupational Safety and Health Acts: (1) temporarily leaving the asbestos abatement workplace; (2) tasks with less airborne asbestos; and (3) physically breaking or cutting using a machine. Conclusions: The problems and improvement measures identified in this study of asbestos abatement companies can be utilized as fundamental information for the improvement of the systems and policies for safe asbestos abatement.

• Advances in environmental research
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• 제6권2호
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• pp.127-137
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• 2017

Cotton is the major fiber crop in Pakistan that accounts for 2% of total national gross domestic product (GDP). After picking of cotton, the dry stalks are major organic waste that has no fate except burning to cook food in villages. Present research focuses use of cotton stalks as feedstock for biochar production, its characterization and effects on soil characteristics. Dry cotton stalks collected from agricultural field of Bahauddin Zakariya University, Multan, Pakistan were combusted under anaerobic conditions at $450^{\circ}C$. The physicochemical analysis of biochar and cotton stalks show higher values of % total carbon, phosphorus and potassium concentrations in biochar as compared to cotton stalks. The concentration of nitrogen was decreased in biochar. Similarly biochar had greater values of fixed carbon that suggest its role for carbon sequestration and as a soil amendment. The fourier transformation infrared spectroscopic spectra (FTIR) of cotton stalks and biochar exposed more acidic groups in biochar as compared to cotton stalks. The newly developed functional groups in biochar have vital role in increasing surface properties, cation exchange capacity, and water holding capacity, and are responsible for heavy metal remediation in contaminated soil. In a further test, results show increase in the water holding capacity and nutrient retention by a sandy soil amended with biochar. It is concluded that cotton stalks can be effectively used to prepare biochar.

• Bulletin of the Korean Chemical Society
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• 제35권1호
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• pp.243-249
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• 2014

Three single crystals of fully dehydrated $Co^{2+}$-exchanged zeolite Y (Si/Al = 1.56) were prepared by the exchange of $Na_{75}$-Y ($|Na_{75}|[Si_{117}Al_{75}O_{384}]$-FAU) with aqueous streams 0.05 M in $Co(NO_3)_2$, pH = 5.1, at 294 K for 6 h, 12 h, and 18 h, respectively, followed by vacuum dehydration at 673 K. Their single-crystal structures were determined by synchrotron X-ray diffraction techniques in the cubic space group Fd3m at 100(1) K. They were refined to the final error indices $R_1/wR_2$ = 0.0437/0.1165, 0.0450/0.1228, and 0.0469/0.1278, respectively. Their unit-cell formulas are $|Co_{29.1}Na_{11.8}H_{5.0}|[Si_{117}Al_{75}O_{384}]$-FAU, $|Co_{29.8}Na_{11.0}H_{4.4}|[Si_{117}Al_{75}O_{384}]$-FAU, and $|Co_{30.3}Na_{9.5}H_{4.9}|[Si_{117}Al_{75}O_{384}]$-FAU, respectively. In all three crystals, $Co^{2+}$ ions occupy sites I, I' and II; $Na^+$ ions are also at site II. The tendency of $Co^{2+}$ exchange slightly increases with increasing contact time as $Na^+$ content and the unit cell constant of the zeolite framework decrease.

• Membrane and Water Treatment
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• 제7권3호
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• pp.223-240
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• 2016

In this study, poly(vinyl-alcohol) and water insoluble ${\beta}$-cyclodextrin polymer (${\beta}$-CDP) cross-linked with citric acid, have been used as macrocyclic carrier in the preparation of polymer inclusion membranes (PIMs) for aniline (as molecule model) extraction from aqueous media. The obtained membranes were firstly characterized by X-ray diffraction, Fourier transform infrared and water swelling test. The transport of aniline was studied in a two-compartment transport cell under various experimental conditions, such as carrier content in the membranes, stirring rate and initial aniline concentration. The kinetic study was performed and the kinetic parameters were calculated as rate constant (k), permeability coefficient (P) and flux (J). These first results demonstrated the utility of such polymeric membranes for environmental decontamination of toxic organic molecules like aniline. Predictive modeling of transport flux through these materials was then studied using design of experiments; the design chosen was a two level full factorial design $2^k$. An empirical correlation between aniline transport flux and independent variables (Poly ${\beta}$-CD membrane content, agitation speed and initial aniline concentration) was successfully obtained. Statistical analysis showed that initial aniline concentration of the solution was the most important parameter in the study domain. The model revealed the existence of a strong interaction between the Poly ${\beta}$-CD membrane content and the stirring speed of the source solution. The good agreement between the model and the experimental transport data confirms the model's validity.

• 한국포장학회지
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• 제19권1호
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• pp.11-15
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• 2013

도서관 등에서의 책의 위생적 유통과 관리를 위한 방안을 찾기 위하여 보관되는 책 및 관련된 환경 오염원에서의 미생물 오염도를 측정하였고, 미생물 부하를 저감시키는 방안에 대하여 연구하였다. 일반적으로 책 내부 표면의 오염도는 매우 낮으며 부주의한 취급으로 침 등과 같은 액체에 의해서 오염되는 경우에 미생물 부하가 증가될 수 있었다. 그리고 책 내부 표면에 비해서 먼지가 축적되기 쉬운 옆끝면에서 미생물 오염부하가 높았다. 책에서의 미생물적 오염의 다양성을 고려할 때, 책의 청결도 유지를 위한 조작으로서는, 미생물 부하가 많은 먼지 등의 건조 분체 오염은 공기와류 장치를 사용하고, 습윤상태의 오염은 280 nm UV LED를 사용하는 것이 적절한 것으로 나타났다. UV LED에 의한 미생물 사멸에서는 2 cm 정도의 가까운 거리에서 약 5분 정도 이상의 조사가 효과적이었고, 공기 와류에 의한 건조 분체 오염부하을 저감시키는 조건으로는 풍속 5.5 m/s에서 30초~1분의 처리가 적절하였다.

• 의료ㆍ복지 건축 : 한국의료복지건축학회 논문집
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• 제29권3호
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• pp.37-44
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• 2023

Purpose: To decrease cross-infection, it's essential to analyze the spatial composition of the 'PPE doffing area'. Instead of solely relying on manpower standards, we should focus on responding to infectious diseases within the context of space planning. By doing so, we can lower the risk for healthcare workers' infection and ensure a level of safety in various environmental changes or new manpower input situations. Methods: This analysis is conducted specifically for facilities with negative pressure isolation wards. Additionally, interview surveys to obtain feedback from healthcare workers and incorporate their expertise into the design of the 'PPE doffing area' have been carried. Results: In a PPE doffing area, the standard spaces include a PPE doffing room, a shower room, and a clothing room. Depending on the facility environment or the level of infectious diseases, a Decontamination room or Anteroom can be optionally added. Healthcare workers who remove their PPE in the PPE doffing room should avoid re-entering the Negative pressure room. The shower room is often underutilized. When planning for a future PPE doffing area, an aisle space or passageway must be included even if a shower room is planned. Implications: This study examined the space used by healthcare workers rather than patients, with a focus on infection prevention through architectural planning rather than individual efforts. However, the investigation was limited to facilities that have been converted from general wards to negative pressure isolation wards, so it cannot be generalized to all infectious disease facilities.

• 한국농림기상학회지
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• 제8권4호
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• pp.222-228
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• 2006

본 연구는 온산 공단지역 산림토양과 그곳에 우점하고 있는 인동덩굴의 기관별 중금속(As, Cd, Cr, Cu, Fe, Mn, Ni, Pb, Zn) 함량을 분석하고 산림토양과 식물체간 중금속 함량의 상관관계를 규명하여 덩굴식물인 인동덩굴을 중금속 오염지의 토양 정화 및 식생복원에 대한 기초 자료를 제공하는데 목적이 있다. 토양중금속 중 As, Cd, Cu, Pb, Zn은 공단지역이 산림지역보다 유의적으로 높은 함량을 나타낸 반면 Fe, Mn 및 Ni 함량은 산림지역이 공단지역보다 유의적으로 높은 것으로 나타났다. 중금속 중 Cd, Cu, Pb과 Zn은 인동덩굴의 잎, 줄기, 뿌리에 있어서 공단지역에서 자라는 식물체의 함량이 산림지역의 함량보다 유의적으로 높은 것으로 나타났다. 산림토양의 As, Cd, Cu, Pb, Zn 함량과 인동덩굴 기관별 함량은 높은 정의 혹은 부의 상관을 보여주었으며, Cu가 산림토양과 인동덩굴의 기관간에 $0.93{\sim}0.99$의 가장 높은 상관계수를 나타내었다. 인동덩굴 식물체의 기관 내 높은 중금속 함량과 산림토양과의 높은 상관계수를 고려하면, 인동덩굴은 공단지역과 같이 중금속(특히 Cd, Cu, Pb와 Zn)에 오염된 산림토양에서 정화식물로 이용할 수 있을 것으로 판단된다.