• Restorative Dentistry and Endodontics
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• 제21권2호
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• pp.585-601
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• 1996

The purpose of this study was to elucidate the effect of blood-and saliva-contamination during dentin pretreatment procedure on tensile bond strength, and to investigate the effect of contaminant-removing treatments on the recovery of bond strength of dentin bonding agents. Dentin specimens prepared from freshly extracted bovine mandibular anterior teeth were divided into non-contaminated control and contaminated experimental groups. The specimens of the contaminated group were contaminated with saliva or blood after etching or priming procedure, followed by contaminant-removing treatments. All the specimens were bonded with All Bond$^{(R)}$ 2 dentin bonding agent and Bisfil$^{TM}$ composite resin or Scotchbond$^{TM}$ Multipurpose and Z100. After all the bonded specimens were stored in $37^{\circ}C$ distilled water for 24 hours, tensile bond strengths were measured. The contaminated dentin and fractured dentin surfaces were examined under the scanning electron microscope. The results were as follows : Contaminated specimens showed lower bond strength than non-contaminated ones regardless of the kind of contaminant, contamination time and contaminant-removing treatments, except specimens which were acid-etched following saliva contamination after etching in All Bond$^{(R)}$ 2 groups (p<0.05). Blood contaminant resulted in much bond strength decrease than saliva ones (p<0.01), and contamination after priming resulted in much decrease in bond strength than after etching (p<0.01). Re-etching resulted in increase of bond strength in the specimens contaminated with saliva after etching but not in blood contaminated ones. Re-priming resulted in increase of bond strength in the specimens contaminated after priming regardless of the kind of contaminant.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2005년도 INTERNATIONAL SYMPOSIUM ON SOIL & GROUNDWATER ENVIRONMENT
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• pp.62-63
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• 2005

• 한국초전도ㆍ저온공학회논문지
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• 제17권4호
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• pp.38-42
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• 2015

In terms of food safety,mixture of contaminants in food is a serious problem for not only consumers but also manufacturers. In general, the target size of the metallic contaminant to be removed is 0.5 mm. However, it is a difficult task for manufacturers to achieve this target, because of lower system sensitivity. Therefore, we developed a food contaminant detection system based on high-Tc RF superconducting quantum interference devices (SQUIDs), which are highly sensitive magnetic sensors. This study aims to improve the signal to noise ratio (SNR) of the system and detect a 0.5 mm diameter steel ball. Using a real time digital signal processing technique along with analog band-pass filters, we improved the SNR of the system. Owing to the improved SNR, a steel ball with a diameter as small as 0.3 mm, with stand-off distance of 117 mm was successfully detected. These results suggest that the proposed system is a promising candidate for the detection of metallic contaminants in food products.

• 보존과학연구
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• 통권24호
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• pp.29-60
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• 2003

The conservation problem of stone cultural properties is widely influenced by environmental pollution nowadays as well as agingsymptoms itself. Most stone cultural properties are directly affected by air pollution such as smoke, acid-rain, etc., resulting surface separation and pulverization. In the case of Ten storied pagoda of Gyeongcheonsa, once located in the center of the Seoul, the surface shows excessive contaminant by air pollution. It is very difficult to identify chemical structure and formation system of these contaminant. Also the discoloration and stains on the surface are not pleasant to see. Through the examination of the contaminant by SEM-EDS, it is observed that the major mineral is Gypsum and many other minerals were also revealed. The contaminant layer seems to be thin and wide at the south face of pagoda and thick and narrow at the north face. This distribution pattern could provide information on the surface characteristics of pagoda. Further, the information could help to identify the relationship between geological and environmental factors and the surface patterns.

• 한국지하수토양환경학회지:지하수토양환경
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• 제24권3호
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• pp.13-23
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• 2019

The purpose of this study is to suggest conceptual models based on finite numerical method that can be used to assess contaminant transport through subsurface and estimate exposed concentration at contaminated site. This study tested various assumptions of the numerical models for contaminant transport in unsaturated and saturated zones to simulate the pathways to the human exposal point. For this purpose, models for seven possible scenarios of contaminant transport were simulated using the numerical code MODFLOW and MT3D. The simulation results that showed different peak concentrations and travel times were compared. In conclusion, the potential utility of the numerical models in the site specific risk analysis suggested as well as future research ramifications.

• Current Research on Agriculture and Life Sciences
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• 제32권1호
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• pp.30-33
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• 2014

김치의 숙성과정 중 일어날 수 있는 식품위생상 이물질의 오염방지를 위하여 혼입시험을 고안하여 이를 모니터링 하였다. 먼저, 시험군은 소금으로 절이고 양념으로 버무린 김치였고, 대조구는 소금에 절이지 않았거나 양념을 하지 않은 배추를 선택하였다. 오염원으로는 배추와 색깔이 유사한 청개구리를 선택하였다. 그 결과, 염분이 첨가되지 않은 대조구에서는 오염원이 10일 이상 생존하였으나 염분이 첨가된 시험구의 이물질은 5일 이상 생존할 수 없었다. 김치제조 중에 혼입된 생물학적 이물질은 대개 5일 정도 생존하므로 소비자에 의하여 살아있는 상태로 발견된 사실은 제조 후에 혼입되었다고 추정할 수 있다.

• Spatial Information Research
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• 제6권1호
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• pp.65-76
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• 1998

대기오염을 관리하기 위해서는 대기오염 농도와 함께 대기오염 배출량의 공간분포가 정확히 산정되어야 한다. 기존의 대기오염 분포도에서는 토지이용 분류도의 해상도(rdsolution)가 낮아 같은 위치에서 오염원별 토지이용이 중복되었기 때문에 배출량의 정확한 공간분포를 산정할 수 없었다. 본 연구에서는 토지이용분류도를 고해상도(28.5m x 28.5m)로 작성하므로써 이것이 배출량의 공간분포 산정과 대기오염농도의 추정에 미치는 영향을 파악하였는데, 결과를 요약하면 다음과 같다. GIS를 이용하여 비교적 고해상도(28.5m x 28.5m)의 토지이용 분류도를 작성하므로써 점 및 선 오염원이 면 오염원과 동일한 지점에서 중보되지 않도록 토지이용을 효율적으로 반영할 수 있었다. 서울지역에 대해 기존으 방법으로 작성된 배출량 분포도와 본 연구에서 작성된 배출량 분포도를 이용하여 대기오염 농도를 추정(TCM-2모형을 이용)한 결과 본 연구에서 작성한 배출량 분포도에 의한 대기오염 농도의 추정지가 자동측정망의 실측치에 근접함을 알 수 있었다.

• 한국지하수토양환경학회지:지하수토양환경
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• 제15권6호
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• pp.37-45
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• 2010

Surfactant-enhanced ozone sparging (SEOS), an advanced version of SEAS (surfactant-enhance air sparging) was introduced in this study for the first time for removal of non-volatile contaminant from aquifer. The advantages of implementing SEAS, enhanced air saturation and expanded zone of sparging influence, are combined with the oxidative potential of ozone gas. Experiments conducted in this study were tow fold; 1-dimensional column experiments for the changes in the gas saturation and contaminant removal during sparging, and 2-dimensional box model experiment for the changes in the size of zone of influence and contaminant removal. An anionic surfactant (SDBS, sodium dodecylbenzene sulfonate) was used to control surface tension of water. Fluorescein sodium salt was used as a representative of watersoluble contaminants, for its fluorescence which is easy to detect when it disappears due to oxidative degradation. Three different gases (air, high-concentration ozone gas, and low-concentration ozone gas) were used for the sparging of 1-D column experiment, while two gases (air and low-concentration ozone gas) were used for 2-D box model experiment. When SEOS was performed for the column and box model, the air saturation and the zone of influence were improved significantly compared to air sparging without surface tension suppression, resulted in effective removal of the contaminant. Based on the experiments observations conducted in this study, SEOS was found to maintain the advantages of SEAS with further capability of oxidative degradation of non-volatile contaminants.

• 한국지반신소재학회논문집
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• 제19권4호
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• pp.1-9
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• 2020

본 연구는 비정상류 조건에서 오염원 유출을 방지하기 위한 경사식호안 해상폐기물매립장 차수시스템에서 오염원의 이동을 알아보기 위하여 해석을 수행하였다. 차수시스템은 바닥과 측면으로 구성하였다. 바닥차수시스템은 불투수 점토층이 측면차수시스템은 HDPE 차수시트가 주 역할을 하고 부수적으로 중간보호층이 차수를 담당한다. SEEP/W와 CTRAN/W 프로그램을 이용하여 침투·이류 분산 해석을 실시하였다. 해석결과, 조석에 따른 수위변동을 고려한 비정상류 조건 하 에서의 전수두, 간극수의 유속벡터가 시간에 따라 크기 및 방향이 바뀌고 오염원 분산 농도가 변화하였다. 조석차 2m일 경우와 8m일 경우를 비교하면 조차가 클수록 비정상류조건에서의 오염물의 농도가 증가하였다. 오염원 농도 변화율이 조석의 변화에 따라 오염원 농도 변화율 기울기의 변화되어 결과적으로 오염원 유출이 정상류 상태에 비하여 작은 것으로 나타났다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2003년도 봄 학술발표회 논문집
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• pp.189-196
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• 2003

Soil-cement column is often used as a contaminant barrier. This study presents the results of experimental study performed to investigate the changes of properties of soil-cement column under the attack of acids. Sulfuric nitric, and ascetic acid were used as contaminants. Specimen were made of clayey and sandy soils with addition of cement and water Permeability of soil-cement decreased with time during permeability test. When significant amount of acid percolated the specimen, permeability increased and compressive strength decreased due to the dissolution and leaching of cement and its chemical reaction compounds. Sulfuric and nitric acid were more effective than ascetic acid in deteriorating soil-cement column. Amount of acid required to lower the pH of soil cement below 12 was calculated from the results of permeability tests. This leads to a conclusion that, under the conditions employed in this study, the chemical stability of soil-cement column could be maintained against acid attack for longer than generally accepted lifetime of contaminant barriers.