• Restorative Dentistry and Endodontics
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• 제28권3호
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• pp.203-208
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• 2003

The purpose of this study was to evaluate the effect of salivary contamination of teeth on bonding efficacy of self-priming and self-etching DBSs. The materials used were Single Bond(SB, self-priming system, 3M), Unifil Bond(UB, self-etching system, GC), and Scotchbond Multi-Purpose Plus(SM, 3M) as control. Forty five human molars randomly allocated to three groups as dentin bonding systems tested and embedded in epoxy resin. Then the specimens were wet-ground to expose flat buccal enamel surface or flat occlusal dentin surface and cut bucco-lingually to form two halves with slow speed diamond saw. One of them was used under non-contamination, other under contamination with saliva. The bonding procedure was according to the manufacturer's directions and resin composite(Z-100, 3M Dental Products, St. Paul, MN) was built-up on the bonded surface 5mm high. The specimens were ground carefully at the enamel-composite interface with fine finishing round diamond bur to create an hour-glass shape yielding bonded surface areas of $1.5{\pm}0.1\textrm{mm}^2$. The specimens were bonded to the modified microtensile testing apparatus with cyanoacrylate, attached to the universal testing machine and stressed in tension at a CHS of 1mm/min. The tensile force at failure was recorded and converted to a tensile stress(MPa). Mean values and standard deviations of the bond strength are listed in table. One-way ANOVA was used to determine significant difference at the 95% level. The bond strength of SBMP and SB were not affected by salivary contamination, but that of UB was significantly affected by salivary contamination. These results indicate that DBSs with total etch technique seems less likely affected by salivary contamination in bonding procedure.

• 영어영문학
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• 제57권6호
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• pp.1089-1109
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• 2011

In an attempt to demonstrate in context of Nietzsche's "overman" (ubermensch) and Heidegger's "Being-in-the-World" (Dasein) the collective human efforts to overcome humanism in crisis, I will provide the ground for the poetics of overcoming, the ground which are based upon the double movements of transhumanism and transnationalism. For this purpose, I will turn to the theories of two distinctive poets who reveal and disreveal their truths about the subjecthood or the subjectivity in terms of overcoming: Christopher Dewdney for posthuman transhumanity and Dionisio D. Martinez for transnational cultural contamination Transhumanism represented by Christopher Dewdney manifests an interfusion of outside and inside, thereby collapsing the boundary between the mind and the world, and provides a breakthrough from the limitedly defined mind to the transhuman perspective of overcoming by using terminalogy and techniques from science and technology. The emerging transhumanism reflects the growing interdependence between humans and bio technologies, and suggests a potential improvement of human beings. The main argument of transhumanism is that we humans can and should continue to develop in all possible directions, by overcoming our human limitations by shedding the body and having the disembodied consciousness which will liberate our mind. Kwame Anthony Appiah's "cultural contamination" is another form of overcoming as well as a way to otherness, a counter-ideal of cultural purity which sustains authentic culture, reversing the traditional binary opposition between enriching authenticity and threatening hybridization. Dionisio Martinez's poetry sublimates the negative side of Appiah's concept of contamination, by redeeming the value of the Appiah's list of the ideal of contamination such as hybridity, impurity, intermingling, the transformation that comes of new and unexpected combinations of human beings, a bit of this and a bit of that is how newness enters the world. When a poetic subject is doubly exiled and doubly homeless away from his/her native homeland and home of native language, one has no more identification with the authentic culture of both home and away, but rather anticipates a new identity as a transnational subject to cross the bridge beyond cultural authenticity and to enter into the field of cultural contamination.

• 물과 미래
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• 제6권2호
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• pp.19-29
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• 1973

The progressive contamination of water resulted from man's activity and the use of fertilizers is not restricted only to surface water, but also the shallow groundwater is affected. This type of groundwater contamination is mainly restricted to areas composed of permeable, nonconsolidated sediments forming a shallow aquifer. The chloride and the sulfate resulted from man's activity and the use of fertilizers were measured to study the variations of the groundwater contamination. In general, (1) When water level rises, the rate of groundwater contamination becomes less and when water level declines, the rate of contamination is increased. (2) The highly contaminated season is the early-summer and the less contaminated season is the winter or after rainy season. (3) The groundwater in weathering zone without covering layer. (4) The degree of contamination of wells is increased with the increase of well depth and lowing the water table, because of increasing contaminated water from enlargement of the area of influence of the well.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2000년도 가을 학술발표회 논문집
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• pp.401-406
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• 2000

Spilling of petroleum hydrocarbons such as gasoline, motor oils, and diesel fuel from underground storage tanks (USTs) is a major source of contamination to ground water and soils. In response to the need of developing an effective and economical cleanup technique, this study investigates the effectiveness of using sonication to enhance the soil flushing method. The study involves laboratory testing, and the testing was conducted using a specially designed and fabricated device to determine the effect of sonication on contaminant removal. The sonication was applied at 20 kHz frequency under different power levels. Test soil was Joomoonjin Sand, and diesel fuel was used as a contaminant of soil flushing test. The results of the investigation show that sonication enhanced the contaminant removal from soils significantly, and the degree of enhancement varied with power levels of sonication. Based on the results of the study, it is concluded that the flushing method with sonication has a great potential to become an effective method for removing petroleum hydrocarbons from the contaminated ground.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2004년도 임시총회 및 추계학술발표회
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• pp.138-141
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• 2004

The environmental tracers tritium/helium-3 (3H/3He) and chlorofluorocarbons (CFCs) were investigated in ground water from Jeju Island, Korea, a basaltic volcanic island. The apparent 3H/3He and CFC-12 ages were in relatively good agreement in samples with low concentrations of terrigenic He. Ground water mixing was evaluated by comparing 3H and CFC-12 concentrations with mixing models, which distinguished old water with negligible 3H and CFC-12, young water with piston flow, and binary mixtures of the two end members. The ground water CFC-12 age is much older in water from wells completed in confined zones of the hydro-volcanic Seoguipo formation in coastal areas than in water from the basaltic aquifer. Comparison of major element concentrations in ground water with the CFC-12 age shows that nitrate contamination processes contribute more solutes in young water than are derived from water-rock interactions in non-contaminated old water. Chemical evolution of ground water resulting from silicate weathering in basaltic rocks reaches the zeolite-smectite phase boundary. The calcite saturation state of ground water increased with the CFC-12 apparent (piston flow) age. In agricultural areas, the temporal trend of nitrate concentration in ground water was consistent with the known history of chemical fertilizer use on Jeju Island, but the response of nitrate concentration in ground water to nitrogen inputs follows an approximate 10-year delay. Based on mass balance calculations, it was estimated that about 40% of the nitrogen applied by fertilizers reached the water table and contaminated ground water resources when the fertilizer use was at the highest level.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 1997년도 총회 및 춘계 학술발표회 논문집
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• pp.43-46
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• 1997

The results of an investigation conducted to study the effect of crude oil contamination on the geotechnical properties of sand of presented. The effect of the degree of oil contamination on compaction characteristics, shear strength, and one-dimensional compression characteristics has been investigated. The test results indicate that the compaction characteristics are somewhat influenced by oil contamination. The angle of internal friction of sand (based on total stress basis) decreases due to the presence of oil within the pore spaces in sand. The compression characteristics of sand are significantly-influenced by oil contamination. The details of the tests conducted and the results are presented in the paper.

• 한국전기전자재료학회논문지
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• 제23권5호
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• pp.413-417
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• 2010

Line to ground faults by deterioration of insulators has frequently occurred in power system, and the main cause is surface contamination of the insulators. The contamination of insulator is analyzed by monitoring the surface leakage current flowing them. The suspension insulator is monitored by installation of a zero-phase current sensor(ZCT), but the line-post insulator is impossible to apply the same method because of its large diameter structure. This paper proposed a detection method of surface leakage current for a line-post insulator, and it can easily be applied to new and/or built insulators. The leakage current is indirectly calculated from the potential difference between the metal electrode attached on the surface of insulator and the ground connector. To evaluate the performance of the proposed method, the leakage current is compared as a function of contamination condition controlled by the density of NaCl solution. The leakage current is proportioned to the density of NaCl solution, and the voltage detected by the electrode showed the same trend. From the experimental results, we designed and fabricated a monitoring device which is composed of a detection electrode, signal converter, microprocessor, and ZigBee, and its measurement range is $10{\mu}A{\sim}5mA$.

• 한국지반공학회지:지반
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• 제13권6호
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• pp.37-44
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• 1997

본 연구는 토질 역학적인 측면에서 원유로 오염된 사질토의 압축강도 특성, 전단강도, 투수계수, 지지력 특성을 통하여 원유로 오염된 모래의 물리적 거동을 파악하였다. 실험 결과에 의하면 원유로 오염된 모래 지반의 내부마찰각이 오염되지 않은 지반의 내부마찰각보다 간극속에 있는 원유로 인하여 감소하고 있으며,오염도에 따라서 강도정수들 또한 현저한 영향을 보이고 있다. 모래지반의 지지력은 원유오염 도에 따라 크게 영향을 받는다.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2004년도 총회 및 춘계학술발표회
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• pp.209-212
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• 2004

Soil environment has not received much attention from the environmental impact assessor community although soil contamination may affect human health and the eco-system. This study was the first trial to discuss the role and importance of soil environment in the environmental impact assessment(EIA) and suggest possible environmental impact assessment schemes for soil. The objectives of the study were to show the effects of soil contamination on human health, the environment and the social community, suggest efficient EIA schemes in Korea and establish the basic concepts of soil environment assessment involving fate and transport of contaminants and its risk.

• 자원환경지질
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• 제32권5호
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• pp.485-493
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• 1999

In order to dermine the degree of contamination for the Ilgok landfill site, stream water, groundwater and stream sediment samples were collected in 1998 and 1999, and analyzed for physico-chemical properties. The stream water contains significanr concentrations of TDS $HCO_3^-$and $NO_3^-$, and ground-water is polluted by $NO_3^-$ up to the drinking water standard from landfill leachate. From the point of the horizontal movement of elements, stream water IL-2 at the conjunction point with landfill leachate reached the most high concentrations of $HCO_3^-,Cl^-,Na^+, K^+, NO_3^-,Mg{^2+}$ and $SO_4^{2-}$stream water Il-3 shows the high concentrations of $Ca^{2+}, Pb^{2+}$ and $Mg^{2+}$. The optimum contamination indicator of Ilgok landfill site is $HCO_3^-, C^l-, Na^+, Mn^{2+}$ and TDS from the calculation of contamination factor.