• Journal of Korean Society of Environmental Engineers
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• v.27 no.10
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• pp.1043-1051
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• 2005

In this stduy, adsorption and transport characteristics of Fe in the soil were investigated using convection-dispersion local equilibrium sorption model and two-site non-equilibrium sorption model. In batch experiments with different Fe concentration, characteristics of Fe adsorption was investigated using Freundlich and linear isotherm. Column experiments with different flow rate, organic matter content md Fe concentration were also carried out. We measured Fe concentrations in injection-liquid and in effluent, and then applied them to CXTFIT program. As a result of column experiments, some parameters(D, R, ${\beta}$, ${\omega}$) used in two-site non-equilibrium adsorption model were obtained. Characteristics of Fe transport were analyzed using the parameters(D, R, ${\beta}$, ${\omega}$) obtained from the CXTFIT program, Consequently, characteristics of Fe transport in the soil were predicted through two-site non-equilibrium adsorption model.

• Proceedings of the Korea Water Resources Association Conference
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• 2012.05a
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• pp.105-105
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• 2012

최근 우리나라는 집중호우로 인한 토석류의 발생이 현저하게 증가하고 있으며, 2002년 태풍 루사와 2003년 매미 그리고 2006년 7월 집중호우 등으로 인한 피해의 규모는 여러 조사와 문헌에서도 확인할 수 있다. 2011년 7월, 서울 우면산 일대에서는 집중호우로 인한 토석류가 발생하였으며, 16명의 인명손실을 포함한 큰 피해가 있었다. 우면산 토석류는 십여 개 지역에서 동시다발적으로 발생하였으며, 토석류 발생 유역 특성과 토석류의 유동특성을 분석하기 위한 현장 조사가 진행되었다. 조사한 자료에 따르면 우면산 일대의 일일 강우량은 서초 기상측정소를 기준으로 최대 24시간 누적 324mm 그리고 시간당 최대 68.5mm/hr를 기록하였다. 상업용 소프트웨어인 FLO-2D는 유사농도의 함수로서 점성(viscous)응력, 항복(yield)응력, 난류 및 분산(dispersive) 응력항을 포함하는 2차 유변학(quadratic rheology) 모델을 기본으로 사용하여 이류(mudflow)와 토석류(debris flow)를 모의할 수 있다. FLO-2D는 흐름의 운동량 및 에너지 보존을 고려하여 격자와 시간에 관계없이 유동심도, 속도, 압력을 예측할 수 있으며, 격자 기반의 모델로서 GIS 및 기타 응용 프로그램들과 연동이 쉽다는 장점이 있다. 그러나 하상침식에 의해 유발된 토석류의 체적 증가는 고려 할 수 없으므로 토석류의 전파 및 퇴적영역에서의 토석류 모의에만 사용할 수 있는 단점이 있다. 이 연구의 목적은 FLO-2D 소프트웨어를 이용하여 우면산에서의 토석류 현상을 재현하는 것이다. 우면산 일대에서 발생한 토석류 중 서초구 방배동의 래미안 아파트 부근에서 발생한 토석류에 대하여 수치지도(DEM)와 현장조사를 통해 얻은 지형자료, 해당 지역의 강우량 및 지질 특성 자료 등을 토대로 FLO-2D 모델을 적용하여 토석류의 흐름특성을 검토한다. 토석류 유동 및 퇴적에 대한 가용한 현장관측 자료와의 비교 분석을 통하여 토석류 특성 값을 산정하고, 모델의 적용성을 검증한다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.11 no.4
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• pp.103-112
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• 1991

In this study, a numerical model was established and applied to simulate the steady-state groundwater and heat flow in an isotropic, heterogeneous, three dimensional aquifer system with uniform thermal properties and no change of state. This model was developed as an aid in screening large groundwater-flow systems as prospects for underground waste storage. Driving forces on the system are external hydrologic conditions of recharge from precipitation and fixed hydraulic head boundaries. Heat flux includes geothermal heat-flow, conduction to the land surface, advection from recharge, and advection to or from fixed-head boundaries. The model uses an iterative procedure that alternately solves the groundwater-flow and heat-flow equations, updating advective flux after solution of the groundwater-flow equation, and updating hydraulic conductivity after solution of the heat-flow equation. Dierect solution is used for each equation. Travel time is determined by particle tracking through the modeled space. Velocities within blocks are linear interpolations of velocities at block faces. Applying this model to the groundwater-flow system located in Jigyung-ri. Songla-myun, Youngil-gun. Kyungsangbuk-do, the groundwater-flow system including distribution of head, temperature and travel time and flow line, is analyzed.

• Journal of the Korean association of regional geographers
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• v.16 no.2
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• pp.110-122
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• 2010

This article is to study the characteristics of Chungju geographical names using the concepts which are the place identity, the politics of scale, and the competition of place names' territory for the diverse study methods of geographical names. According to this results, the new name of 'Suanbo-Myun' revealed the place identity, because it has not only the property of 'Suanbo hot spring' but also the three conditions called 'the numerical solitary', 'the qualitative identity', and 'the self-identity' which are the conditions for the place identity. In relation to the politics of scale through place names, the example of scaling up is 'Yian-Myun' which is former name of 'Chungju city Yiru-Myun', and the cases of scaling down are 'the up and down of Chungju Up Ho', the reductional change from 'Chungju-Gun' to 'Chungju-Myun' and the change of Chinese name of the 'Wolak Mountain'. Lastly, the examples of place names' territory change are two types. One is 'Chungju Yongdu-Dong' and 'Yiru-Myune Geumgok-Ri' for the cases that the place name and its territory were changed. The other is 'Dalchon river' that the place name's territory was only changed. In conclusion, this study suggested that place names are useful in order to represent and construct the place identity.

• Journal of Soil and Groundwater Environment
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• v.13 no.4
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• pp.54-61
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• 2008

Permeable reactive barriers (PRBs) technology has been focused in contaminated groundwater remediation. It is necessary to select adequate reactive material according to characteristics of contaminant in groundwater. In this research, the reaction between reactive material and heavy metal contaminants was estimated through column test. Reactive material was slag, which has been produced in Gwangyang power plant, and heavy metal contaminants were cadmium, lead and copper. Column test was performed in the condition of 1) single and multi contaminated solution and 2) different initial concentration of cadmium. Retardation factor of cadmium is 3.94 in multi contamination. But that of copper is 40.3 in single and 25 in multi. The difference of retardation between cadmium and copper is due to affinity, resulted from the difference of electronegativity. In multi-contamination, copper effluent concentration was above initial copper concentration and at the same time lead effluent concentration was decreased. This phenomenon was considered that lead extract copper sorbed in slag and then lead was sorbed to the vacant sorption site instead. And as the initial concentration was increased, the retardation factor of cadmium became decreased.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.24 no.4
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• pp.277-286
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• 2012

In the numerical simulation of wave fields using a multi-phase flow model that considers simultaneous flows of materials with different states such as gas, liquid and solid, there is need of an accurate representation of the interface separating the fluids. We adopted an algebraic interface capturing method called tangent of hyperbola for interface-capturing(THINC) method for the capture of the free-surface in computations of multi-phase flow simulations instead of geometrical-type methods such a volume of fluid(VOF) method. The THINC method uses a hyperbolic tangent functions to represent the surface, and compute the numerical flux for the fluid fraction functions. One of the remarkable advantages of THINC method is its easy applicability to incorporate various numerical codes based on Navier-Stokes solver because it does not require the extra geometric reconstruction needed in most of VOF-type methods. Several tests were carried out in order to investigate the advection of interfaces and to verify the applicability of the THINC method to wave fields based on the one-field model for immiscible two-phase flows (TWOPM). The numerical results revealed that the THINC method is able to track the interface between air and water separating the fluids although its algorithm is fairly simple.

• Journal of the Korean Geographical Society
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• v.48 no.2
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• pp.204-217
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• 2013

This study shows the geomorphological processes of Yuga alluvial fan at Dalseong-gun, Daegu in Korea, based on characteristics of geomorphological surfaces, analysis of geomorphological deposits and OSL age dating. Alluvial fans of this area are classified into three surfaces(YG-F1, YG-F2, YG-F3) and were formed by the depositional processes resulting from the changes in hydraulic geometry of flowing water which was a stream flowing out of mountains debouched on to a plain, not by a sudden decrease in surface gradient of river bed. YG-F3 surface, about 110,000 yr B.P.(MIS 5.4), was formed as Yongri river deposited a lot of debris. This result was due to the process that the deposition took place actively with the upward of base level as the last interglacial period began. Later, the denudation of the river valley and geomorphological surface constantly occurred and the local and seasonal changes were found in precipitation and stream discharge with the beginning of the interstadial of the last glacial stages(MIS 3), leading to YG-F2 formed by debris flow, earth flow, mud flow and stream flow. Then, short-term climate changes and temporal climate events repeatedly caused aggradation and denudation over time and going through these processes, YG-F1 is believed to have been made by earth flow or mudflow during the last glacial maximum(MIS 2).

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.3
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• pp.662-669
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• 1994

In the combustion system, the optimum spray conditions reduce the pollutant emission of exhaust gas and enhance the fuel efficiency. The spray characteristics-the drop size, the drop velocity, the number density and the mass flux, become increasingly important in the design of combustor and in testifying numerical simulation of spray flow in the combustor. The purposes of this study are to clarify the spray characteristics of twin-fluid nozzle and to offer the data for combustor design and the numerical simulation of a spray flow. Spatial drop diameter was measured by immersion sampling method. The mean diameter, size distribution and uniformity of drop were analyzed with variations of air/liquid mass flow ratio. The results show that the SMD increases with the liquid supply flow rate and decreases with the air supply velocity. The radial distribution of SMD shows the larger drops can diffuse farther to the boundary of spray. And the drop size range is found to be wider close to the spray boundary where the maximum SMD locates.

• Journal of ILASS-Korea
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• v.1 no.1
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• pp.63-75
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• 1996

The purpose of this study is to investigate the break-up characteristics by taking advantage of a two-phase coaxial nozzle. Air and water are utilized as working fluids and the mass ratio air/water has been controlled to characterize the atomization, diffusion and development of mixing process. By way of a photographic technique, conventional developing structures and diffusion angles have been analyzed systematically with variations of mass ratios. The turbulent flow components of the atomized particles were measured by a two channel LDV system and the data were treated by an on-lined measurement equipment. According to the photographic results the spreading angles decreased because the axial inertia moment was relatively higher than the lateral one with respect to the increase of mass ratio. It is found the jet flow diffuses linearly in a certain limit region while the atomizing characteristics, in terms of the distributions of particle diameters did not show particular differences. It may be expected that these fundamental results can be used as reference data in studying the atomization, breakup and diffusions.

• Journal of ILASS-Korea
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• v.4 no.1
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• pp.19-26
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• 1999

An experimental study of twin-fluid atomization for powder metallurgy has been conducted using a specially designed atomizer in which liquid is first spread into a thin sheet and then exposed on both sides to high-velocity air. Inner air jet worked for supplying liquid and outer air jets disintegrated liquid sheet. The first result of this study were confined to the effect of atomizing quality through experiments with water. The experimental data will be extend to include the influence of atomizing air velocities on mean particle size through experiments with molten material. An experimental equation on the relationship between SMD and the related parameters was taken out; $$SMD=0.00302\frac{{(\sigma_L\;\rho_L\;D_L)}^{0.5}}{\rho_A(V_1+1.155\;V_2)/2}(1+\frac{W_L}{(W_{A1}/3.33)+W_{A2}})+0.0148(\frac{{\mu_L}^2}{\sigma_L\;\rho_L})^{0.425} \;{D_L}^{0.575}(1+\frac{W_L}{(W_{A1}/3.33)+W_{A2}})^2$$.