• Toxicological Research
• /
• 제31권3호
• /
• pp.221-226
• /
• 2015

With the diversification and internationalization of the food industry and the increased focus on health from a majority of consumers, food safety policies are being implemented based on scientific evidence. Risk analysis represents the most useful scientific approach for making food safety decisions. Total diet study (TDS) is often used as a risk assessment tool to evaluate exposure to hazardous elements. Many countries perform TDSs to screen for chemicals in foods and analyze exposure trends to hazardous elements. TDSs differ from traditional food monitoring in two major aspects: chemicals are analyzed in food in the form in which it will be consumed and it is cost-effective in analyzing composite samples after processing multiple ingredients together. In Korea, TDSs have been conducted to estimate dietary intakes of heavy metals, pesticides, mycotoxins, persistent organic pollutants, and processing contaminants. TDSs need to be carried out periodically to ensure food safety.

• 한국지하수토양환경학회지:지하수토양환경
• /
• 제25권2_spc호
• /
• pp.86-100
• /
• 2020

Analyzing and monitoring environmental contaminants based on geophysical exploration techniques have become important and it is now widely applied to delineate spatial distribution geophysical characteristics in wide area. Among the techniques, induced polarization (IP) method, which measures polarization effects on electrical potential distribution, has drawn much attention as an effective tool for environmental monitoring since IP is sensitive to changes in biochemical reactions. However, various reactions stemming from the presence of multiple contaminants have greatly enhanced heterogeneity of polluted sites to result in highly variable electrical characteristics of the site. Those contaminants influence chemical and physical state of soil and groundwater to alter electrical double layer, which in turn influences polarization of the media. Since biochemical reactions between microbes and contaminants result in various IP effects, IP laboratory experiments were conducted to investigate IP responses of the contaminated soil samples under various conditions. Field IP surveys can delineate the spatial distribution of contamination, while providing additional information about electrical properties of a target medium, together with DC resistivity. Reviewing IP effects of contaminants as well as IP surveys can serve as a good starting point for the application of IP survey in site assessment for environmental remediation.

• 한국지반환경공학회 논문집
• /
• 제15권11호
• /
• pp.13-19
• /
• 2014

투수성 반응벽체 공법은 지하수 오염을 정화하는 대표적인 방법 중의 하나이다. 영양염류와 중금속 등 여러 가지 오염물질이 동시에 존재하는 경우 두 가지 이상의 반응성 매질을 적용한 반응벽체공법으로 복합오염물질의 제거가 가능하다. 본 연구에서는 반응성 매질로 제올라이트와 제강슬래그를 함께 사용하는 경우 복합오염물질의 제거능을 평가하였다. 영양염류인 암모늄과 인산염, 중금속인 카드뮴이 혼합된 복합오염물질에 대하여 연속회분식실험을 통하여 제올라이트 및 제강슬래그와의 반응순서에 따른 오염물질 제거능을 분석하였다. 연속회분식실험 결과에 의하면 제올라이트-제강슬래그 순서로 반응하는 경우 영양염류와 중금속의 복합오염물질에 대한 제거능이 더 좋은 것으로 나타났다.

• 한국동물위생학회지
• /
• 제31권4호
• /
• pp.547-554
• /
• 2008

Bacteriospermia is a frequent finding in fresh boar semen and can result in detrimental effects on semen quality and longevity. The objectives of this study was to evaluate types of bacterial contaminants in porcine fresh semen and the reducing effect of antibiotic and density gradient with percoll on the bacterial contaminants. Fresh semen was collected by gloved-hand method into a pre-warmed($37^{\circ}C$) thermostable bottle, and was inoculated onto blood agar and MacConkey agar, respectively. After incubated for 48 hour, 7.5% $CO_2$ at $37^{\circ}C$, bacterial colonies were selected and identified by Gram staining, oxidase test, catalase test and finally identified using API kits and Vitek system. Aerobic culture yielded a variety of bacteria from different genera. The most prevalent contaminant of fresh semen were Leclecia adecarboxylata, Acineobacter banmanni, Staphylococcus epidermidis, Staphylococcus cohni spp urealyticus, Proteus mirabilis. Most of identified bacteria were Gram(-) and non-pathogenic bacteria. It seems that bacterial contaminants in fresh semen were seem originated from multiple sources at the stud/farm, and were from animal and non-animal origins. Gentamicin treatment did not eliminate the bacterial contaminants completely but 3 step-density gradient with percoll completely removed the bacterial contaminants in fresh semen. Therefore, future study is necessary to prove that density gradient method with percoll can eliminate bacteria in fresh semen without significantly affecting sperm viability or function.

• 한국동물위생학회지
• /
• 제33권4호
• /
• pp.319-326
• /
• 2010

Bacteroiospermia is a frequently finding in fresh raw and extended porcine semen and can results in detrimental effects on semen quality and longevity. This study aims to evaluate the type of bacterial contaminants in raw and extended porcine semen and the reducing effect of antibiotic test. To investigate bacterial contaminants, out of 387 sample (raw semen 201, extended semen 186) were collected from 6 artifical insemination centers in Gyeongsangnam-do, were inoculated onto blood agar and MacKonkey agar, respectively. Bacterial colonies were selected after culturing for 48 hours, at $37^{\circ}C$, followed by Gram staining, KOH test, oxidase test, catalase test and eventually identified using VITEK System. Total 15 genus and 24 species of bacteria were isolated from these semen samlpes. In raw semen, the most prevalent contaminants were Pseudomonas aeruginosa, Escherichia coli, Proteus mirabilis, Staphylococcus auricularis, Delftia acidovorans, Acinetobacter lowffii, S. aureus and others. And in extended porcine semen, A. lowffii, S. aureus, S. auricularis and other bacteria were identified. Most of them was G(-), which is nonpathogenic bacteria. It seems that bacterial contaminants in fresh raw and extended porcine semen originated from multiple sources at the farms/stud, and were from animal origin and non-animal origins. Whereas, the 7 virus which is known to be detected in porcine semen in 75 cases was not detected. This results showed that removal of bacterial contamination in raw and extended porcine semen is essential and farms were kept for biosecurity and individual hygienes.

• 한국식품위생안전성학회지
• /
• 제27권1호
• /
• pp.37-41
• /
• 2012

현재 복어독의 표준 시험법은 다른 나라들과 마찬가지로 마우스를 이용한 동물시험법으로 명시되어 있다. 그러나, 살아있는 동물에게 고통을 주는 동물실험의 규제 확대로 인해 기기분석 시험법으로의 개선이 요구되고 있다. 또한, 동물시험법의 감도나 정밀성 및 정확성의 한계로 최근에 동물시험법을 대체할 수 있는 시험법에 대한 연구가 활발히 진행되고 있다. 본 연구에서 LC/MS/MS 시험법은 시료에서 테트로도톡신을 추출한 후 SPE(Solid phase extraction) 정제칼럼을 이용하여 정제하고 양이온 모드에서 MRM(multiple reaction monitoring)방법으로 분석하는 시험법으로서 밸리데이션 결과 검출한계(LOD)는 부위에 따라 $0.03{\sim}0.08{\mu}g/g$이었고, 정량한계(LOQ)는 $0.10{\sim}0.25{\mu}g/g$이었다. 검량선의 상관계수($r^2$)는 0.9986~0.9997이고, 회수율은 80.9%~103.0%이었으며 상대표준편차(RSD)는 4.3%~13.0%로서 적합한 시험법임을 확인하였다. 이 시험법을 이용하여 복어 검체의 부위별로 분석을 실시하였으며, 동물시험법의 시험결과와의 상관관계를 분석한 결과, 상관계수는 0.95이상의 상관성을 확인하였다.

• Environmental Engineering Research
• /
• 제20권3호
• /
• pp.205-211
• /
• 2015

Reduced forms of iron, such as zero-valent ion (ZVI) and ferrous ion (Fe[II]), can activate dissolved oxygen in water into reactive oxidants capable of oxidative water treatment. The corrosion of ZVI (or the oxidation of (Fe[II]) forms a hydrogen peroxide ($H_2O_2$) intermediate and the subsequent Fenton reaction generates reactive oxidants such as hydroxyl radical ($^{\bullet}OH$) and ferryl ion (Fe[IV]). However, the production of reactive oxidants is limited by multiple factors that restrict the electron transfer from iron to oxygen or that lead the reaction of $H_2O_2$ to undesired pathways. Several efforts have been made to enhance the production of reactive oxidants by iron-induced oxygen activation, such as the use of iron-chelating agents, electron-shuttles, and surface modification on ZVI. This article reviews the chemistry of oxygen activation by ZVI and Fe(II) and its application in oxidative degradation of organic contaminants. Also discussed are the issues which require further investigation to better understand the chemistry and develop practical environmental technologies.

• Tribology and Lubricants
• /
• 제38권4호
• /
• pp.121-127
• /
• 2022

This study presents the development of an integrated oil purification system consisting of moisture removal, oil flushing, and oil filtering devices. In this system, the oil flushing device is combined with a micro-bubble generator. Oil purification is necessary for ensuring the high performance of the lubricant through the efficient removal of contaminants and thus enables good maintenance of mechanical systems. The developed purification system removes moisture, varnish, and solid particles. Moreover, during oil purification, the oil flushing device separates foreign materials and contaminants remaining in the lubricating oil piping or mechanical systems. The microbubble generator, which is combined with the oil flushing device, can separate harmful contaminants, such as sludge, wear particles, and rust, from piping or lubrication systems through the cavitation effect. Moisture is removed using a double high-vacuum chamber, while sludge and varnish are removed via electro-absorption using a high-voltage generator. Additionally, the total maintenance cost of the system is reduced through the use of domestically fabricated cartridge filters composed of glass fiber and cellulose. The heater, which maintains the temperature of the lubricant at 60℃, can process 41,000 L of lubricant simultaneously. Multiple tests confirmed that the proposed integrated purification system exhibits good performance in oil flushing and removal of water and varnish.

• Nuclear Engineering and Technology
• /
• 제55권1호
• /
• pp.12-24
• /
• 2023

With the improvement of laser technology, the strategic needs of efficient and precise decontamination of various components in nuclear application units can be fulfilled by laser decontamination. The surface contaminants of nuclear facilities mainly exist both as loose contaminated layer and fixed oxide layer. The types of radionuclides and contamination layer thickness are closely related to the operation status of nuclear facilities, which have an important influence on the laser decontamination process. This study reviewed the mechanism of laser surface treatment and the influence of laser process parameters on the decontamination thickness, decontamination factor, decontamination efficiency and the distribution of aerosol particle. Although multiple studies have been performed on the mechanism of laser processing and laser decontamination process, there are few studies on the microscopic process mechanism of laser decontamination and the influence of laser decontamination on surface properties. In particular, the interaction between laser and radioactive contaminants needs more research in the future.

• 한국지하수토양환경학회지:지하수토양환경
• /
• 제16권1호
• /
• pp.51-61
• /
• 2011

Germination tests were conducted to determine the practical concentration levels at which plants can reproduce naturally during the phytoremediation of soils contaminated with a high concentration of petroleum hydrocarbons and heavy metals. The effects of humic acids on plant growth and soil physicochemical properties were also investigated. The results show that phytoremediation can be applied in soils contaminated by multiple contaminants at the former soil contamination potential level of Korean soil quality standards considering successful natural reproduction. It was observed that germination rates of Helianthus annuus and Festuca arundinacea were high after all treatments, and transplantation was more appropriate for Phragmites communis in phytoremediation. Humic acids had a positive effect on the growth of both aboveground and belowground biomass of herbaceous plants. Growth inhibition by multiple contaminants is more severe in the case of aboveground biomass. Germination and growth tests suggest that Helianthus annuus is a suitable phytoremediation plant for soils contaminated with a high concentration of petroleum hydrocarbons and heavy metals. The addition of humic acids also caused changes in the physicochemical properties of contaminated soils. An increase in the carbon and nitrogen content due to the addition of humic acids and a correlation between cation exchange capacity(CEC) and the organic matter content were observed.