Earticle

2022년 3월 4일 울진군에서 발생한 산불은 삼척시까지 확산되었으며 213시간만에 주불이 진화된 국내 역대 최장 기간의 산불로 기록되었다. 이로 인하여 약 209.23km2의 산림이 소실되었고, 약 1,500억원 이상의 재산피해가 추정되며, 약 6,500명이 대피하였다. 이러한 대형산불에 대한 다양한 논문과 정책 등의 연구가 진행되고 있으나, 대부분 산불의 직접적인 영향에 대하여 고려하고 있고, 산불의 연기로 인한 간접적인 영향에 대해서는 연구가 부족하다. 본 연구에서는 2022 울진-삼척 산불에 대하여 산불 연기의 주성분인 이산화탄소의 확산에 대해서 시뮬레이션을 수행하였고, 산불 로 인한 미세먼지의 증가에 따라 공기오염에 의한 산불 피해 주민의 건강에 대한 영향성을 추정하고 자 하였다. 산불로 인한 이산화탄소와 미세먼지는 증가하는 것으로 나타났으며, 산불 피해 주민에게 영향이 있었을 것으로 판단된다. 향후 해당지역의 호흡기 질환자 등에 대한 정보 수집을 통해 피해 정도를 추정하여 피해지 복구 관리와 지속적인 주민의 건강상태를 체크하는 데에 도움이 될 수 있을 것으로 사료된다.

The wildfire that occurred in Uljin-gun on March 4, 2022 spread to Samcheok-si, and was recorded as the longest wildfire in Korea, with the main fire extinguished in 213 hours. Due to the wildfire, about 209.23 km2 of forest was lost, more than 150 billion won in property damage, and about 6,500 people were evacuated. Even if various papers on these large-scale wildfires have been studied in Korea, most of them are considering the direct impacts of wildfires. Studies on indirect impacts such as damage to human health due to wildfire smoke are still lacking. In this study, numerical simulation was performed on the spread of carbon dioxide that the major material of wildfire smoke, for the 2022 Uljin-Samcheok wildfire and the air pollution on the resident health affected was estimated according to the increasing fine dust by wildfires. The amount of carbon dioxide and fine dust caused by wildfires has been increasing, and it is believed that it may have had an influence on the residents. In the future, it is thought that it will be helpful in estimating the extent of damage by collecting information on people with respiratory diseases.

본 연구는 본류와 지류의 하상경사 및 유사 유입조건이 다르며, 하폭이 넓고 수심이 상대적으로 얕은 합류부에서 흐름 및 하상변동에 관하여 수치모의를 수행하여 그 특성을 파악하는데 목적이 있다. 적용 대상지역은 금강과 미호천의 합류부로서, 흐름특성 및 하상변동을 모의하기 위하여 RMA-2와 SED2D를 이용하였다. 유량의 증가에 따라 흐름에 대한 유속과 전단층의 길이가 증가하고, 합류부의 우안의 정체수역에서 발생하는 와(vortex)의 크기도 증가하였다. 부유사의 농도는 실제 상황에 맞도록 비평형 유입조건을 사용하였으며, 미호천에서 유입되는 유사의 농도에 영향을 받아, 합류직후에도 유사의 농도가 높고, 전단층을 경계로 하여 농도 띠가 하류로 유지되었으며, 합류 후에는 우안에서 하상이 상승되었다.

The Cable in Conduit Conductor (CICC) configurations are designed, tested and realized to make high field superconducting (SC) magnets. The evolution of CICC design makes it challenging to forecast thermo-hydraulic behavior. A common objective of thermo-hydraulic studies is to obtain the most reliable predictive correlation for friction factor in CICC geometries and to reduce the dependency on the experiment. So far, only the void fraction and Reynolds number have been considered in the predictive correlations in an explicit way. In the present paper, the CICC twisting pattern dependency, called tortuosity (𝜏), on the pressure drop prediction, has been assessed through a numerical simulation approach. The CICC twisting pattern with 6+1 petals (solid conductor in the present study) with different twisting pitches is mimicked in the numerical simulation for the range 100 ≤ Re ≤10000 and 1 < 𝜏 < 1.08 and a correlation for friction factor, f, has been proposed as a function of Re and 𝜏.

토석류는 우리나라 주요 산지토사재해 중 하나로, 토석류로 운송된 다량의 토사가 하류 지역에 퇴적 되어 인명 및 재산피해를 일으키기 때문에 토석류로 인한 피해 범위를 예측하여 경계 피난을 위한 기초자료로 활용하는 것이 중요하다. 우리나라 산림청은 Random Walk Model(RWM)을 활용하여 토석류 피해예측지도를 구축하였다. 한편, 산지계류에 설치되는 사방댐은 토석류 유출을 차단하여 피해면적을 감소시키므로 효과적인 토석류 피해예측지도 활용을 위해서는 사방댐의 효과가 고려되 어야 한다. 이 연구에서는 강원도 소재 9개 사방댐 설치 유역에 대해, 사방댐의 효과를 고려한 RWM 토석류 유출 및 퇴적 모의를 통해 토석류 피해예측지도에 대한 사방댐 효과 적용 가능성을 검토하였 다. 분석결과 RWM을 통해 사방댐의 효과는 일정 부분 재현 가능하였으나, 입력 매개변수 및 모델 구성의 한계로 피해예측범위의 수정은 제한될 것으로 판단되었다. 향후 공간해상도의 개선 및 합리 적 붕괴토사량의 산정을 통해 사방댐의 효과를 반영한 효과적인 토석류 피해예측지도 구축이 가능 할 것으로 판단된다.

Debris flow transports lots of sediments downstream that cause damage to human lives and properties. The accurate estimation of the debris flow hazard zone is a critical factor of the successful early-warning and evacuation for reducing the debris flow risk. Korea Forest Service has developed a debris flow hazard map using Random Walk Model (RWM). Meanwhile, because check dams in forest watersheds capture discharged debris, the effect of check dams should be considered for mapping the debris flow hazard zone. This study analyzed the effect of check dams on debris flow discharge using RWM with the check dam module. As a result, RWM seems to simulate the sediment capture by check dams. However, the total deposit areas were not significantly different despite the effect of check dams because of input parameters and the flow direction calculation algorithm of RWM. Further studies on appropriate spatial resolution and initial sediment volume should be conducted to improve the debris flow hazard map.

이 연구의 목적은 침식 및 퇴적을 고려하여 토석류를 모의하는 것이다. 현재, 토석류를 연구하는 가장 효과적인 방법은 수치모형을 이용하는 것이다. 기존의 수치모형의 대부분은 침식 및 퇴적을 고려하지 못했다. 본 연구에서는 침식 및 퇴적을 고려할 수 있는 Egashira(1997)방법을 이용하여 수치모의를 수행하였다. 토석류가 하류에 멈추어 설 때까지는 침식이 우세하게 나타났다. 유량이 증가함에 따라 최대침식 발생량은 증가하였고, 발생위치도 하류로 이동하였다. 토석류의 진동은 상류로부터 수로 길이 40% 지점을 통과한 이후로는 소멸하는 것으로 나타났다.

The purpose of this study is to simulate the debris flow considering the erosion and the sedimentation. Currently, the effective method for studying and estimating the debris flow is to use numerical model. Most of numerical models in the published research do not consider the erosion and the sedimentation. In this study, the numerical simulation was performed by using Egashira’s method(1997) which is considered the erosion and the sedimentation. The erosion at the channel was dominant until debris flow was reached at the downstream of the channel. As the inflow was increased, the amount of peak erosion was increased, and the occurring point of it more moved down to stream of channel. The fluctuation of debris flow was disappeared after passing through the 40% point of channel length from the upstream.

In this study we investigated ac transport current losses in the face to face stack for the anti-parallel current flow, and compared the electromagnetic properties with those of the single SC tape as well as those of the same stack for the parallel current path. The gap between the SC tapes in the stack varied in order to verify the electromagnetic influence of the neighbors when current flows in opposite direction, and the model was implemented in the finite element method program by the commercial software, COMSOL Multiphysics 4.2a. Conclusively speaking, the loss was remarkably decreased for the anti-parallel current case, which is attributed the magnetic flux compensation between the SC layers due to the opposite direction of the current flows. As the gap between SC tapes was increased, the loss mitigation became less effective. Besides, the current density distribution is very flat cross the sample width for the narrower gap case, which is believed to be benefit for the power electric system. These results are all in good agreement with those predicted theoretically for an infinite bifilar stack.

국문초록본 연구에서는 2011년 우면산 토석류 피해지역을 대상으로 지상 LiDAR (Light Detection And Ranging) 측량을 통해 토석류 발생 후의 지형의 변화를 관측하였다. LiDAR 측량을 위해서 고해상도 디지털 카메라와 GPS가 장착된 RIEGLE LMS-Z390i모델의 지상스캔닝시스템이 이용되었다. 최상류지점에서의 하상경사는 15-25°의 범위를 보이며 발생지점에서 500m정도까지의 거리에서는 경사도가 10°이상으로서 비교적 큰 경사를 보였다. 500m이후에는 경사도가 감소하여 0-10°의 범위를 보이며 특히 1,000m이후에는 5°보다 낮게 유지되었다. 침식과 퇴적을 고려하는 수치해석 모의를 실시하였다. 수치모의는 Takahashi의 침식/퇴적속도식을 적용한 유한차분법을 이용하였다. 계산결과에서 500m이내 대부분의 지역에서는 1.5m깊이로 침식이 발생하며 500-1,000m구간에서 침식과 퇴적이 반복적으로 나타나고 있으며 1000m이후 구역에서는 퇴적이 우세하게 나타나는 것을 보였다. 수치모의 결과는 현장에서의 침식과 퇴적의 경향을 잘 표현하고 있다고 판단되며 이후 재해위험지도 등에 활용가능하다고 생각된다.

This study was carried out to estimate the behavior of the debris flow, which was occurred at Umyensan-area in Seoul, Korea in 2011. In this study, we surveyed the topological change by debris flow using terrestrial LiDAR (Light Detection And Ranging) at Umyensan area. For the LiDAR measurement, the terrestrial laser scanning system consists of a highly accurate and fast 3D scanner associated GPS system and high-resolution digital camera were used. The bed slope of the most upstream has the range of 15-25° and kept high slope over 10° until run-off distance of 500m. however the slope decreased to the range of 0-10° at the midstream of debris track. The numerical simulation was performed by using the Finite Differential Element method (FDM) based on the equation for the mass conservation and momentum conservation and erosion/deposition velocity which was proposed by Takahashi. The erosion was increased steeply in high bed slope area within 500m and the deposition was dominant at the downstream of 1,000m. From the comparison with measured data and simulation result, this model was thought to be able to apply to the hazard map

The first full-scale countermeasures against flood disasters were carried out at 17th century in Japan. The Saga Plain is one of the places that include such flood damage prevention facilities. At present, several facilities are left and can be seen as historic remains. It is significantly useful to find out and restore these remains and clarify their functions to consider a future flood control including catchment basin operations. In this study, overflow embankments and open levees are focused on the investigated field for estimating a controlled water flow spreading the retarding basin with sediment transports. A geotechnical sampling method is adopted in this research to obtain a plate-like sample that can be easily analyzed for estimating water flow velocity, flow direction and a process of sediment settling. An additional investigation of numerical simulation is implemented to estimate water flow on the retarding basin from the overflow embankment. Flow analysis of theriver gave a boundary condition for anotherdetail simulation of flood flow on the retarding basin. The results of geotechnical investigation and hydraulic approach show the inundated water flow is controlled in the retarding basin of the residential area. The result of this study gives a quantitative evaluationof the flood control including catchment basin operations for the river basin management.

토석류 재해가 발생한 지역에 대한 연구를 진행함에 있어 어려움 중의 하나는 연구자가 토석류 피해지역에서 연구를 수행하기 위한 충분한 시간을 확보하기 전 이미 복구활동이 시작되어 토석류 특성을 파악하기 위한 피해현장의 보존이 어렵다는 것이다. 또한 경제적이고 효율적으로 토석류 현상을 재현하는 것과 재해지도(Hazard Map)의 제작을 위한 피해범위 예측에 사용될 토석류 해석모형에 대한 적절한 평가와 적용에 대한 연구의 진행은 미흡한 실정에 있다. 따라서 본 연구에서는 집중호우에 의해 유발된 토석류 발생지역에 대해 최근 항공 LiDAR와 더불어 활용도가 높아지고 있는 지상 LiDAR를 이용하여 피해지역을 보존 및 분석하는 방안을 검토해보고 토석류의 흐름과 유출에 대해 토석류 수치해석프로그램인 Kanako 2D를 적용하여 피해지역을 해석하였다. 연구결과 지상 LiDAR를 이용한 토석류 피해지의 조사는 피해지역에 대해 정도 높은 3차원 가상공간을 생성함으로써 후속 연구에 대한 유용한 기초자료로 활용가치가 높음을 알 수 있었다. 또한 Kanako 2D프로그램을 이용한 간단한 방법으로 토석류 모의를 수행할 수 있어 토석류발생 위험지역에 대한 예측에 활용할 수 있을 것으로 기대된다.

In this study, we analyze the debris flow damaged area of Jecheon, Chungbuk. And we estimate behavior of debris flow by the debris flow occurred using the Kanako 2D debris flow numerical model. The intensive rainfall over 455mm occurred between on 9 to 14 July 2009. It was triggered debris flows around the mountain area in Jecheon. For the natural slopes of Korea, the extent of outcrop development is one of the critical factors to control the debris flow. In well-developed outcrop region, landslide is hard to occur. However, in the area where bedrocks are exposed, there are the cases that the debris flows down along the valley when heavy rainfall occurs. In this study case, debris flow was occurred by the deposits accumulated are eroded due to the fast flows in the bed of the mountain valley. For the LiDAR(Light Detection And Ranging) measurement, the terrestrial laser scanning system RIEGL LMS-Z390i consists of a highly accurate and fast 3D scanner associated GPS system and high-resolution digital camera were used.

Recently, landslides frequently occur on natural slope and/or man-made cut slope during periods of intense rainfall. With a rapidly increasing population on or near steep terrain, landslides have become one of the most significant natural hazards. Thus, it is necessary to protect people from landslides and to minimize the damage of houses, roads and other facilities. To accomplish this goal, many landslide monitoring systems have been developed throughout the world. In this paper, a simple landslide detection system that enables people to escape the endangered area is introduced. The system is focused on the debris flows which happen frequently during periods of intense rainfall. The system is based on the wireless sensor network (WSN) that is composed of wireless sensor nodes, gateway, and remote server system. Wireless sensor nodes and gateway are deployed by commercially available Microstrain G-Link products. Five wireless sensor nodes and one gateway are installed at the test slope for detecting ground movement. The acceleration and inclination data of test slope can be obtained, which provides a potential to detect landslide. In addition, thresholds to determine whether the test slope is stable or not are suggested by a series of numerical simulations, using geotechnical analysis software package. It is obtained that the alarm should be issued if the x-direction displacement of sensor node is greater than 20mili-meters and the inclination of sensor node is greater than 3 degrees. It is expected that the landslide detection method using wireless senor network can provide early warning where landslides are prone to occur.

경제성장에 따른 공업화, 산업화로 업종이 다양해짐에 따라 발생되는 대기오염물질의 종류 및 그 양이 지속적으로 증가하고 있다. 현대에는 생산공정의 발달로 미세분진의 발생량이 지속적으로 증가하고 있으며, 정부의 규제가 강력해짐에 따라 미세분 진 처리를 위한 대기오염방지시설 연구·개발이 진행되고 있다. 현대에는 다양한 종류의 오염물질을 효과적으로 제거하기 위해 충격기류식 여과집진장치를 사용하고 있다. 충격기류식 여과집진장치의 설계 및 운영에 가장 중요한 요소는 압력손실로, 압력 손실을 줄이기 위한 최적의 탈진 조건은 거의 확립되어있지 않아, 대부분의 산업 현장에서는 충격기류식 여과집진장치를 경험 적으로 운영하고 있다. 본 연구에서는 수치해석 시뮬레이션을 통해 여과포 직경, 탈진압력, 압축공기 공급 노즐 직경에 따른 충 격기류식 여과집진장치의 탈진 성능을 최적화하였다. 시뮬레이션 결과 탈진압력과 노즐 직경이 늘어날수록 압축공기 공급량이 증가하였으며, 효과적인 탈진을 위해서는 노즐 직경 10mm, 12mm에서 5 bar 이상의 탈진압력이 필요한 것으로 나타났다. 여 과속도 1.5 m/min, 노즐 직경 10mm에서 여과포 직경비는 최대 22.5까지 가능하며, 최적 탈진압력은 여과포 수명을 고려하여 5 bar로 판단된다. 직경 12mm의 노즐을 사용할 경우 압축공기공급량이 증가하여 여과속도 1.5 m/min 이하 조건에서는 여과포 직경비는 최대 25까지 설치 가능하여 여과에 필요한 부지 소요면적을 크게 감소시킬 수 있을 것으로 판단된다. 또한 디퓨저를 설치할 경우 압축공기의 유출량이 감소하여 탈진압력 4 bar 조건에서도 효과적인 탈진이 가능한 것으로 나타났다.

As industries diversify due to industrialization and economic growth, the types and amount of pollutants are continuously increased. In modern, by advancing the manufacturing, particulate matter (PM) are emitted dramatically. As regulations become more tighten, the research and development to treat PM is progressing. In modern, a pulse air jet bag filter has used as an effective precipitator for treating various types of dust. The pressure drop is most important factor for designing and operating the pulse air jet bag filter, but the optimal pulsing conditions to decrease the pressure drop are rarely established. The correlations, between the pulsing performances and pulsing conditions, are not verified, so many industries are operating the pulse air jet bag filter empirically. In this study, the main factors affect the pulsing performances were filter bag aspect ratio, pulsing pressure, and nozzle diameter, and for optimizing the performances the CFD (Computational Fluid Dynamics) was used. As nozzle diameter and pulsing pressure increased, total supplying air increased, and for effective pulsing, at nozzle diameter 10 mm, pulsing pressure is 6 bar, and at 12 mm, pulsing pressure is 5 bar. In addition, when the diffuser is applied, the leakage of supplying air is reduced, that the pulsing is possible at 4 bar condition.

Debris flow produce severe damage to buildings and human lives in mountainous areas. Predicting potential deposition area of debris flow is important to reduce the loss or damage. To this end, numerical simulation model is useful prediction tool. In this study, we conducted numerical simulations with a debris flow simulator KANAKO 2D for debris flow event that occurred in Cheonjeon-ri, Chuncheon city, Korea, and compared with aerial image after debris flow event. The simulation results showed that debris flows caused damage to buildings on residential area, and were influenced by topography. In addition, the superposition of aerial image showed that KANAKO 2D model is effective delineation of potential hazard zones.

This paper presents analytical and numerical simulation approaches on charging characteristics of no-insulation (NI) REBCO pancake coil by using the equivalent circuit model to estimate magnetic performance response in the coil. The analytical methods provide closed form or definite solution in the form of complete mathematical expressions but they are hard to solve the complex problems. Numerical methods have become popular with the development of the computing capabilities to solve the problems which are impossible or very hard to solve analytically. First of all, the equivalent circuit model are proposed to develop the simulation code for both analytical and numerical method. The charging test was performed under critical current to obtain magnetic field induced and terminal voltage through the radial as well as spiral current paths within the coil. To verify the validity of both proposed methods, the simulation results were compared and discussed with the experimental results.

에너지원으로서 천연가스의 비중이 점차적으로 증가하고 있으며 천연가스의 경우 전체 에너지 소비량 대비 15% 이상 을 소비할 만큼 중요한 에너지원의 역할을 가지고 있다. LNG의 경우, 천연가스의 청정성, 편리성 및 경제성이라는 장점 으로 인하여 수요가 늘어나고 있으며 또한 LNG 연료추진선박, LNG 자동차 및 버스의 공급을 위한 소형 LNG 저장설비 의 수요가 급증하고 있다. 본 연구에서는 소형 LNG 저장설비에서 가장 큰 사고로 이를 수 있는 Rollover에 대하여 초저 온 유체 계면에서의 Vapor-Liquid Equilibrium을 이용하여 해석을 수행하였다. 해석된 결과를 이용하여 소형 LNG 저장 설비에서의 누출 피해예측 및 분석을 통한 사고영향평가를 수행하여 추후 건설 예정 중인 설비에 대한 안전성을 검토하 고자 한다.

The share of natural gas as an energy source is gradually increasing, and natural gas has an important role as major energy source role that consumes more than 15% of the total energy consumption. In case of LNG, there is an increasing demand due to the advantage of cleanliness, convenience and economy of natural gas and also, demand for the small LNG storage facilities for fuel supplying LNG fuelled vessels, LNG cars and buses is increasing rapidly. In this study, we analyze the rollover case, which is the biggest LNG leakage accident in small LNG storage facility, by using Vapor- Liquid Equilibrium at the cryogenic fluid interface. Using this calculated results, we evaluate the accident impact by prediction and analysis of leakage damage in small LNG storage facility and examine the safety assessment for facilities to be constructed in the future.

The safety production situation for coal mines has been so serious that it was urgent to involve in coal mine risk management in China in recent years. Human induced risk factors were the most important predispositions for accidents in the coal mine systems. Taking one Coal Industry Group Co., Ltd. in Henan province, China as target, the human induced risk factors were comprehensively investigated by the combination of questionnaire survey, interview method and STOP behavior observation method, and then human risk factors used to assess human induced risk status in the Coal Industry Group Co., Ltd. were concluded into five management modules, including 30 concrete human induced risk factors (HIRFs). Further more, the weights of HIRFs were certified by the combination of the weighted average values of expert scored results and frequencies of HIRFs in 210 unsafe behaviors as well as 269 different levels of typical accidents. The results demonstrated that professional quality, basic quality, individual ideology, executive force of safety decision-making and normalization of safety decision-making were the top five important HIRFs in the coal mine systems in China. Reason structure of human induced accidents in the coal mine systems were founded by frequency analysis and logical reasoning, which indicated that professional quality and basic quality accounted directly for the unsafe behaviors while nearly all the HIRFs were observed in the coal mine systems. At the basis of theories discussed above, the relationship between variations of HIRF values and risk levels at the basis of historical data on the official website and data of survey were finally fitted by SIGMPLOT 11.0, and there was a total increase in HIRFs values threshold of (7.44, 18.19) for human induced accidents, that was, accidents below major levels occurred when the HIRF values were lower than 7.44 while the death accidents began to increase when HIRF values were higher than 18.19, which did benefits to prevent and control human induced accidents in the coal mine systems.

기후 변화와 토지 개발로 인해 산지재난의 규모가 대형화되고 그 발생빈도 또한 증가하고 있다. 국토의 64%가 산지로 구성되어 있으며 대부분의 강우가 여름철에 집중되어 있는 우리 나라는 다양 한 산지재난에 취약한 특징을 가지고 있다. 특히, 산사태, 토석류와 같은 산지 재난의 발생 빈도가 높아지면서 산지 재난 저감을 위한 대책 마련이 요구되고 있다. 본 연구에서는 토석류 발생 현장에 대한 조사를 바탕으로 토석류를 모의하고 실제 피해가 발생된 시설물에 대한 취약성을 평가하였다. 모의에 따르면 실제 토석류 피해지역과는 약 62% 정확도로 일치하였고, 실제 피해가 발생된 시설물 이 위치한 구간에서는 약 2.0~24.8kPa의 충격력이 발생하였다. 또 취약성은 0.6 보다 높은 것으로 나타났다.

The scale of mountain disasters and the frequency of their occurrence are increasing due to climate change and land development. The country of 64% is composed of mountainous areas and most of the rainfall is concentrated in summer, making Korea vulnerable to mountain disasters. In particular, as the frequency of landslides and debris flow increases, countermeasures to reduce the mountain disasters are required. In this study, we simulated the debris flow based on the investigation on site where debris flows occurred and evaluated the vulnerability of the facilities that actually damaged. The simulation result coincided with an accuracy of about 62% for the area damaged by the actual debris flow. The impact forces about 2.0 to 24.8 kPa were generated in the section where the actual damage occurred. In addition, the vulnerability was found to be higher than 0.6.

Injection of polymer solutions has been recognized as an effective mobility control process to increase the recovery of oil in mature fields. Polymer flooding is a way to reach the residual oil saturation more quickly or allow it to be reached economically. Evaluating whether a polymer flood is suitable for a given field and developing the optimal design, a considerable analysis using extensive numerical simulations is required prior to full-scale implementation. This paper presents numerical investigations of a two-well model in a five-spot pattern operating under polymer flood process. UTCHEM, a three-dimensional numerical model for fluid flow and mass transport, is used to analyze the performance of the reservoir. The model includes the effects of polymer concentration-dependent viscosities, shear-thinning rheology of the polymer solution, and inaccessible pore volume. This paper places an emphasis on the design and reservoir parameters including slug design, oil viscosity, and absolute permeability. For different parameters of the system, performances were compared in terms of cumulative oil recovery and water-oil ratio at the production well and pressure drop at the injection well. Results of numerical calculations indicate that properties of polymer bank such as concentration and size are shown to impact the predicted recovery. The results also show the effectiveness of using a buffer zone of grading polymer concentration to lessen the unfavorable mobility ratio between the chase water and the polymer solution. It is noted that although an increased recovery is obtained with a lower permeability, the significant increase in the amount of pressure drop at the injection well makes the application impractical.

지표면에서 증발이 일어날 때 비포화 영역 내에서의 물의 이동을 예측하기 위하여 새로운 수치 모델을 개발하였다. 개발한 모델은 기존의 실험법이나 수치 모델들이 균일한 공극으로 구성된 영역에서만 적용할 수 있었던 한계를 극복한 것이다. 최소한의 변수로 공극의 물리적 특성과 토양 입자의 화학적 성질 등을 모두 고려하여 수식화한 비선형 미분방정식을 기초로 개발되었다. 따라서 공극률, 공극 분포, 절대투수율, 계면장력, 접촉각, 상대투수율, 모세관 압력 등의 영향을 포함하고 있다. 유한요소법을 이용하여 비포화 영역 내 물의 이동에 관하여 시뮬레이션하였다. 본 모델을 이용하여 구한 수치 해를 분석함으로써 비균일층의 특성을 나타내는 여러가지 인자들이 비포화 영역 내에서 물의 이동 과정에 미치는 영향을 알 수 있었다.

A new numerical model has been developed to predict water migration through an unsaturated zone undergoing an evaporation at the surface. It overcomes limited applicabilities of previous experimental and numerical models to uniform media. Based on the nonlinear partial differential equation including terms of physical properties of pores and physicochemical characteristics of soil particles, this model can predict the effects of pore size distribution, absolute permeability, interfacial tension, contact angle, relative permeability, and capillary pressure. The water migration in an unsaturated zone was extensively simulated with a finite-element method. Analysis on the numerical solutions results in quantifying the influences of formation properties on the migration process through an unsaturated zone.