• Journal of Korean Society of Coastal and Ocean Engineers
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• v.18 no.4
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• pp.301-307
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• 2006

In coastal zones with high tidal ranges like Korean western coast, port construction and reclamation projects have been increased. Most of the projects include sea-dyke construction. In the sea-dykes constructed to protect sea water intrusion, sea water was exchanged through the permeable dykes. The water level inside the area enclosed by the dykes changes with time due to tidal action of outer sea, but the tidal range is smaller than that of outside because of strong friction. In numerical modeling of coastal circulation the water exchange through the dykes has been neglected, which has produced inaccurate estimation neglecting the water exchange. In this study a method, which can consider water exchange through sea-dyke, was suggested and the modeling accuracy was improved. A groundwater theory was utilized to explain the phenomena.

• The Journal of Engineering Geology
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• v.14 no.2
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• pp.169-177
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• 2004

The permeation movements of groundwater recharge and contaminate materials receive a eat effect due to porosity and effective porosity of porous media which is composing underground consisted of saturation and unsaturated states. This study developed Frequency Domain Reflectometry(FDR) system and measurement sensor, and then carried out the laboratory experiments to measure effective porosity for unsaturated porous media. Also, I suggested dielectric mixing models(DMMs) which can calculate the effective porosity from relation of measured dielectric constants. In the experimental results the extent range of effective porosity of standard sand and river sand which are unsaturated soil sample were measured in about 65∼85 % for porosity. In relation of effective porosity and porosity, especially, effective porosity confirmed that displays decreasing a little tendency as porosity increases. This is because unsaturated soil did not reach in saturation enough by air of very small amount that exist in pore between soil particles.

• Journal of Korea Soil Environment Society
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• v.4 no.3
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• pp.95-104
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• 1999

Comparative biodegradation studies of liquid and solid alkanes and of two different solid alkanes were conducted by an isolated Acinetobacter sp., which degraded crude oil alkanes simultaneously. for the determination of degradation mechanism of hydrophobic crude oil constituents. Also a model oil experimental system composed of a solid alkane. heneicosane, as a substrate and a non-degradable non-aqueous phase liquid. pristane, as an oil matrix was established and studied. It was proposed that the Acinefobacter sp. utilized hydrophobic substrates directly on the surface of them with no difference in the degradation rates between the liquid and solid alkanes. On the basis of the results from the heneicosane/pristane system which imitates crude oil matrix containing solid constituents. the crude oil matrix was considered to reduce the bioavailability of contained substrates by reducing the specific surface area of substrates to contact with microorganisms.

• Proceedings of the Korea Water Resources Association Conference
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• 2009.05a
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• pp.1939-1944
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• 2009

우리나라의 대표적인 도서지역인 제주도는 일반 내륙지역과 달리 지표수-지하수에 대한 연구가 지하수계에 대한 연구에 비해 미미한 실정이다. 제주도의 경우 내륙과 달리 대부분의 하천이 평상시 건천의 형태로 유지되며, 일정한 강우가 도달해야만 지표유출이 발생하는 경우가 많다. 이와 같은 하천특성은 내륙과 매우 상이하여 일반적으로 사용되는 유역 수문해석 방법으로는 수문성분의 정확한 산정을 기대하기 어렵고 이로 인해 지하수 해석에 있어서도 불확실성이 크게 증가하는 요인이 된다. 따라서 지표수의 정확한 거동과 지하수 해석의 불확실성을 줄이기 위해 유역개념의 물순환을 해석할 수 있는 지표수-지하수 연계 해석기술이 필요한 실정이다. 본 연구에서는 '삼다수 먹는샘물 환경영향조사'가 수행되어 비교적 정확한 지하수위 관측 자료가 확보되어 있고, 매우 제한적이기는 하나 하천의 유출량 조사가 수행된 바 있는 제주 표선 유역에 완전연동형 지표수-지하수 해석 프로그램인 SWAT-MODFLOW을 이용하여 지표수 유출성분과 지하수 유동변화를 동시에 고려한 분석을 수행하였다. 특히 MODFLOW의 Well 패키지와 SWAT의 물이동 옵션을 결합하여 표선유역의 198개 관측공의 양수를 동시에 모의하였다. 모의결과 지하수위는 비교적 양수에 비해 안정되게 유지되는 것을 알 수 있었고 이를 통해 현재 삼다수 공장의 양수량은 현재로서는 과다양수가 아닌 것으로 판단되었다. 현재의 양수량의 10배를 가정하여 모의를 한 결과, 지하수위는 함양에 의해 다시 회복되는 결과를 보이고 있어 이 지역의 실제 개발가능량에 대한 보다 심도있는 논의가 필요한 것으로 판단되었다. 나아가 이와 같은 분석을 통해 제주 지역의 전체의 지하수 개발가능량을 산정할 경우 제주지역의 지하수 관리방안이 새롭게 제시될 수 있을 것으로 기대된다.

• Journal of Environmental Science International
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• v.15 no.7
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• pp.669-676
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• 2006

PAHs are major pollutants that are widely distributed in soil and groundwater environment, so that may be regarded as carcinogens. We investigated the degradation kinetics of PAH in aqueous solution when low pressure UV energy and ultrasonic irradiation were applied. Phenanthrene and pyrene were used as model compounds. The degrees of degradation of these compounds with time were analyzed with a GC/MSD (SIM-mode). UV photolysis experiments showed that phenanthrene was reduced by 90 -67% at initial concentrations of 1 ppm to 8ppm whilst it decreased to 50% at 10 ppm. Under the same conditions pyrene was degraded up to about 75% at lower initial concentrations but the reduction efficiency dropped to a level of 34 to 29% at the higher concentrations above 8 ppm. The reaction orders for phenanthrene and pyrene were found to be zero-th and ca. -0.4th order, respectively, thus implying that the reported assumption of pseudo 1st order reaction for some PAHs would be no longer valid. PAH degradation was roughly proportional to the intensity of UV (number of lamps), exhibiting maximum 92.5% of the degradation efficiency. The solution pH was lowered to 4.4 from 6.4 during the experiments partially because the carbons decomposed by the energy reacted with oxygen radicals to produce carbon dioxides. Ultrasonic irradiation on phenanthrene solutions gave relatively poor results which matched to 50 to 70% of degradation efficiency even at 2 ppm of initial concentration. Phenanthrene was found to be degraded more efficiently than pyrene for the two energy sources. Ultrasound also followed the same reaction kinetics as UV energy on PAH degradation.

• Journal of the Korean Society of Hazard Mitigation
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• v.10 no.5
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• pp.109-116
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• 2010

Infiltration and the rising level of groundwater caused by rainfall are a major cause of the landslide and sliding. In order to secure the safety factor of slope, the slope stabilization and reinforcement works are used to enhance consistency. Nailing, Slope Drainage method and the surface vegetation measures can be simultaneously applied in the Mass Nail method, which is also environmental friendly reinforcement method. To demonstrate the reinforcement effect of a strengthened slope by Mass Nail, the changes in water contents by rainfall were considered while performing Scale Model Test. As a result, safety factor of reinforced slope was about 1.4~2.3 times increased on the unstrength slope. In the case of increasing water content 10% to 22%, The maximum stress was reduced to 12%~24% at the average rate of 18% on the unstrength slope and the reinforced slope by the Mass Nail Method was reduced to 4%~23% at the average rate of 14%.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.3 no.3
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• pp.213-229
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• 2005

Nuclides in radioactive wastes are assumed to be transported in the geosphere by groundwater and probably discharged into the biosphere. Quantitative evaluation of doses to human beings due to nuclide transport in the geosphere and through the various pathways in the biosphere is the final step of safety assessment of the radioactive waste repository. To calculate the flux to dose conversion factors (DCFs) for nuclides appearing at GBIs with their decay chains, a template ACBIO which is an AMBER case file based on mathematical model for the mass transfer coefficients between the compartments has been developed considering material balance among the compartments in biosphere and then implementing to AMBER, a general and flexible software tool that allows to build dynamic compartment models. An illustrative calculation with ACBIO is shown.

• Journal of Korea Soil Environment Society
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• v.3 no.3
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• pp.75-86
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• 1998

This paper is going to show the way we can sample the landfill gases flowing out to the air through final cover soil by using an closed chamber in the field for a short time. In addition, we came to the following results through the application of model with actual measurements. 1) Analyzing changes of concentration in the chamber(H: 10-30cm) every 5 minutes, considering analysis time of gas chromatograph for an half hour. 2) The proportion of $CE_4$to $CO_2$changes rapidly near the surface of final cover soil by the influence of methane oxidation reaction. 3) When flux of landfill gas is F=$10^{-5}$mol/$\textrm{m}^2$.s), methane oxidation reaction has an influence on composition of gases, however there is little influence when F=$10^{-6}$ mol/($\textrm{m}^2$.s).

• Journal of Korea Soil Environment Society
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• v.4 no.1
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• pp.97-108
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• 1999

Reduction 2, 4, 6-trinitrotoluene by zero valent iron was studied in a batch reactor under anoxic conditions. Results showed that the removal of trinitrotoluene (TNT)followed a pseudo-first order reaction and the rate was linearly dependent on the available reactive surfau area of the zero valent iron surface area, resulting a rate constant of 0.0981min$^{1}m$$^{-2}m$. High concentrations of the final product, presumably triaminotoluene which needs to be treated by other means, accumulated in the solution. However , little amount of TAT was extracted from the metal surface by using acetonitrile or phosphate buffered water (pH 7.0). Other common major intermediate in biological TNT degradation, a group of aminodinitrotoluenes, was not detected in the solution. Therefore, it is postulated that the reduction of nitro group by $Fe^0$ occurs simultaneously in all three positions and a TNT reduction model by zero valent iron was suggested.

• Journal of Korean Society on Water Environment
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• v.25 no.1
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• pp.58-68
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• 2009

Low impact development (LID) technique is relatively new concept to reduce surface runoff and pollutant loading from land cover by attempting to match predevelopment condition with various integrated management practices (IMPs). In this study, computational model for designing and evaluating LID, named LIDMOD, was developed based on SCS-CN method and applied at Andong bus terminal to evaluate LID applicapability and design retention/detention area for volume or peak flow control. LIDMOD simulated with 21 years simulation period that yearly surface runoff by post-development without LID was significantly higher than that with LID showing about 2.8 times and LID could reduce efficiently yearly surface runoff with 75% reduction of increased runoff by conventional post development. LIDMOD designed detention area for volume/peak flow control with 20.2% of total area by hybrid design. LID can also efficiently reduce pollutant load from land cover. Pollutant loads from post-development without LID was much higher than those from pre-development with showing 37 times for BOD, 2 times for TN, and 9 times for TP. Pollutant loads from post-development with LID represented about 57% of those without LID. Increasing groundwater recharge reducing cooling and heating fee, creating green refuge at building area can be considered as additional benefits of LID. At the point of reducing runoff and pollutant load, LID might be important technique for Korean TMDL and LIDMOD can be useful tool to calculate unit load for the case of LID application.