• Journal of Ecology and Environment
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• 제35권4호
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• pp.251-258
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• 2012

Many aquatic ecosystems suffer from anthropogenic disturbances, including the introduction of damaging levels of toxic substances. The effects of disturbances include complex relations with various components involved in the systems, and can include physical, chemical, and hydrological disruption depending of the contaminant. Decision Support Systems (DSSs) are developed to help decision makers to deal with complex management crises, through the systematic structuring and evaluation of decisions, and through providing easy-to-use and integrated tools for information elaboration and display. We reviewed various DSSs developed for toxic substances in aquatic ecosystems, and suggested a conceptual framework which is best suited to the management of such issues within Korea. It may assist stakeholders with their decision making process, and in the achievement of a consensus on water management solutions.

• 한국표면공학회지
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• 제32권2호
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• pp.83-92
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• 1999

GaN etching was performed using planar inductively coupled $Cl_2$-based plasmas and the effects of main process parameters on the characteristics of the plasmas and their relations to GaN etch rates were studied. Also, the GaN etch mechanism was investigated using a Langmuir probe and optical emission spectroscopy (OES) during the etching, and X-ray photoelectron spectroscopy (XPS) of the etched surfaces. The GaN etch rates increased with the increase of chlorine radical density and ion energy, and a vertical etch profile haying the etch rate close to 4000 $\AA$/min could be obtained. The addition of 10% Ar to $Cl_2$ gas increased the GaN etch rate and the addition of Ar (more than 20%) and HBr generally reduced the GaN etch rate. The GaN etch rate appeared to be more affected by the chemical reaction between Cl radicals and GaN compared to the physical sputtering itself under the sufficient ion bombardments to break GaN bonds.

• 한국물환경학회지
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• 제22권1호
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• pp.166-171
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• 2006

The objectives of the present paper were to investigate the concentration of total coliform in wastewater effluents and the effect of water chemical and physical characters in it. The most correlated parameter with total coliform was COD. It means that the wastewater treatment efficient effects on total coliform concentration. And we developed predictive model for the total coliform concentration. The estimated parameters for model were COD, temperature, nitrite, chloride, Mn and regression model equation was determined; log (Total Coli.) = 1.861+0.065[COD]+0.038[temperature]-0.0004[$Cl^-$]+3.697[Mn]-0.32 [$NO_2-N$] The developed model provided very strong correlation ($R^2:0.82$) between total coliform and regression equation. The parameters having high sensitivity were COD and temperature. So the study indicated that if the temperature and COD of wastewater effluent were known, we would estimate the concentration of total coliform and decide the most effective usage of chlorine.

• 한국기술혁신학회:학술대회논문집
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• 한국기술혁신학회 2001년도 춘계학술대회:발표자료
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• pp.271-284
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• 2001

Nanotechnology arises from the exploitation of physical, chemical,and biological properties of systems that are intermediate in size between isolated atoms/molecules and bulk materials, where phenomena length scales become comparable to the size of the structure. In addition nanotechnology implies direct control of materials and devices on molecular and atomic scale, including fabrication of functional nanostructures with desired properties, synthesis and processing of nanoparticles, self-assembly, use of quantum effects, etc. This article is a collection of Informations of trend of research and development in the field of nanotechnology in U.S., EU, Japan and Korea. And we would like to include some idea to decide the direction and the strategy for the investment for nanotechnology.

• 한국잠사곤충학회지
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• 제40권1호
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• pp.63-69
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• 1998

Twenty seven out of ca. 5,000 actinomycete strains, which were isolated from soil collected throughout the country, showed antibicrobial effects against fungai, Rhizopus stronifer (ATCC 6227a), Rhizoctonia solani (KCCM 11271) and yeast, Candida albicans (ATCC 10231). From these antifungal microorganisms, we further selected seven strains which seemed to produce insecticidal substances with in vivo test, using silkworm, Bombyx mori and beet armyworm, Spodoptera exigua. Morphological and biochemical experiments revealed that three strains out of seven were Streptomyces. Further investigations on the physical and chemical properties of these antifungal and insecticidal substances are now in progress.

• 한국축산식품학회지
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• 제42권1호
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• pp.34-45
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• 2022

Spirulina platensis was included at 2.5%, 5%, and 7.5% of the diet as a phytobiotic either as a crude preparation or after enrichment by a biosorption process and fed to 126 Japanese quail and the eggs collected and examined for 6 weeks. Assessments were made of physical and chemical characteristics of the eggs. All treatments with added Spirulina increased unsaturated fatty acids and decreased saturated fatty acids with the largest responses for linolenic (omega 3) and oleic (omega 9) acids. The changes in fatty acids were greater with enriched than crude Spirulina. These results suggest that eggs from quail fed with Spirulina may have positive effects on human health.

• 한국유기농업학회지
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• 제21권2호
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• pp.283-294
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• 2013

생강 재배지 토양의 물리 화학적 특성 변화, 생강의 양분 흡수 관계, 생강의 생육 변화를 조사하였다. 시험 전 토양과 생강 수확 후 토양 특성을 비교하면, 시험 전 토양의 전질소 함량은 $0.04{\sim}0.13g\;kg^{-1}$, 치환성 K는 $1.88{\sim}2.80cmol_c\;kg^{-1}$, 치환성 Mg는 $0.41{\sim}0.55cmol_c\;kg^{-1}$, 수확 후 토양의 전질소 함량은 $0.31{\sim}0.95g\;kg^{-1}$, 치환성 K는 $0.47{\sim}1.37cmol_c\;kg^{-1}$, 치환성 Mg는 $1.07{\sim}1.97cmol_c\;kg^{-1}$로서 전질소 함량과 치환성 Mg의 함량은 증가하였고, 치환성 K의 함량은 감소하였다. 식물 양분 중 K, Ca, Zn, Cu의 흡수량이 지상부에서, 망간의 흡수량은 지하부에서 높은 함량을 보였으며, K의 흡수량은 지상부에서 $63.9{\sim}72.3g\;kg^{-1}$, 지하부에서 $27.6{\sim}37.3g\;kg^{-1}$로서 특히 높은 함량을 보였다. 생강 중 K의 높은 흡수량으로 인하여 토양 중 치환성 K의 함량이 수확 후 감소한 것으로 보인다. 생강의 뿌리썩음병은 저지대 및 식양토에서 높은 병발생률을 보였는데, 저지대로의 수분이동과 저지대의 배수 취약성이 병발생을 증가시키고, 토양수분 보유력이 높은 식양토 또한 병발생 증가에 영향을 준 것으로 생각된다. 뿌리썩음병 발생률은 낮게는 26.7%에서, 높게는 88.1%로 나타났는데, 생강 성숙기인 8월과 9월의 고온다습한 기후 조건도 높은 뿌리썩음병 발생의 원인으로 보인다. 생강 뿌리썩음병은 토양의 토성 및 지형 조건에 따른 토양수분의 증가, 고온다습한 기후 조건 등에 따라 발생률이 증가되는 것으로 판단된다. 따라서, 생강 재배지 선정시 지대의 경사, 토성, 배수 system 등이 고려되어야 할 것이다.

• 한국자동차공학회논문집
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• 제12권2호
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• pp.76-82
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• 2004

Biodiesel fuel(BDF) which is easily produced from vegetable oils such as soybean oil and rice bran oil can be effectively used as an alternative fuel in diesel engine. However, BDF can affect the performance and emissions in diesel engine because it has different chemical and physical properties from diesel fuel. To investigate the effects of injection timing on the characteristics of performance and emissions with BDF in IDI diesel engine, BDF derived from rice bran oil was considered in this study. The engine was operated at six different injection timings and six loads at a single engine speed of 2000rpm. When the injection timing was retarded, better results were obtained, which may confirm the advantage of BDF. The reduction of NOx and smoke was observed for a 2$^{\circ}$ retarded injection timing without any sacrifice of BSEC.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2014년도 제49회 KOSCO SYMPOSIUM 초록집
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• pp.21-24
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• 2014

In the entrained-flow coal gasifier, coal ash turns into a molten slag most of which deposits onto the wall to form liquid and solid layers. Critical viscosity refers to the viscosity at the interface of the two layers. The slag layers play an important role in protecting the wall from physical/chemical attack from the hot syngas and in continuously discharging the ash to the slag tap at the bottom of the gasifier. For coal with high ash melting point and slag viscosity, CaO-based flux is added to coal to lower the viscosity. This study evaulates the effect of critical viscosity temperature and ash/flux ratio on the slag behavior using numerical modelling in a commercial gasifier. The changes in the slag layer thickness, heat transfer rate, surface temperature and velocity profiles were analyzed to understand the underlying mechanism of slag flow and heat transfer.

• 환경위생공학
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• 제18권4호
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• pp.36-44
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• 2003

The cement-based system among S/S(Solidification/Stabilization) is widely used to treat hazardous wastes. In this study, tannery sludge was solidified to evaluate the stabilization effects of using admixtures in the cement-based S/S. Fly ash as substitute also used to increase the strength of the S/S of hazardous waste. The compressive strength measurement and leaching experiment of chromium metal of solidified mortar were carried out to compare and evaluate the physical and chemical characteristics of solidified hazardous waste sludge. From the result of this study, there was increased of compressive strength by using AEW-3(early-hardening AE water reducing agent), and leaching concentration of chromium became low enough to satisfy the regulatory criteria. The successful solidification for the organic contaminant and heavy metal in hazardous waste should enable to treat by cement-based system using early-hardening AE water reducing admixture and fly ash as substituted cement.