• Title/Summary/Keyword: 균질기반유동

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A Dye Tracer Study of Infiltration Pattern in a Residual Soil Developed from Granite (화강암 기원 잔적토양에서 염료추적자의 침투 유형에 관한 연구)

  • 전철민;김재곤;이진수;김탁현
    • Economic and Environmental Geology
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    • v.37 no.4
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    • pp.383-389
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    • 2004
  • Understanding flow pattern of water and solute in subsurface is essential for the reduction and prevention of contamination of soil and groundwater and for the investigation and remediation of contaminated site. The objective of this study is to examine the infiltration pattern in a soil developed from the Jurassic granite using (Brilliant Blue FCF $C_{37}H_{34}N_{2}Na_{2}O_{9}S_{3}$), the nonfluorescent and nontoxic food dye. All image processing was conducted using geographic image processing software, ER Mapper, Version 6.2. The dye coverage was determined by counting the stained pixels in the photographs (80${\times}$80cm, 80TEX>${\times}$5cm) for the vertical and horizontal view. A homogeneous matrix flow occurred in the A horizon with weak, medium granular structure and fingering at the interface of finer-textured A horizon and coarser-textured C horizon. Pegmatitic vein originated from the granite and plant root in C horizon induced preferential flow.

CFD Validation of Solid-Liquid Two-Phase flow for Analysis of Drilling Fluid Flow Characteristics (이수의 유동 특성 분석을 위한 고체-액체 2상 유동의 전산유체역학적 유효성 검토)

  • Choi, Yong-Seok;Park, Jae-Hyoun;Bae, Jae-Hwan;Lee, Bong-Hee;Kim, Jeong-Hwan
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.24 no.5
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    • pp.611-618
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    • 2018
  • In this study, numerical analysis of solid-liquid two-phase flow was conducted as a preliminary step to analyze the flow characteristics of drilling fluid using the commercial CFD code, ANSYS CFX 14.5. The homogeneous model and separated flow model were used to simulate solid-liquid two-phase flow phenomena. In the separated flow model, Gidaspow's drag force model was applied with the kinetic theory model was applied for solid particles. The validity of the numerical model used in this study was verified based on the published experimental results. Numerical analysis was carried out for volume fractions of 0.1 to 0.5 and velocities of 1 to 5 m/s in a horizontal tube with a diameter of 54.9 mm and a length of 3 m. The Pressure drop and volume fraction distribution of solid particles were confirmed. The pressure drop was predicted using the homogeneous model and separated flow model within the MAE of 17.04 % and 8.98 %, respectively. A high volume fraction was observed in the lower part of the tube, and the volume fraction decreased toward the upper part. As velocity increased, variations in volume fraction distribution at varying heights were decreased, and the numerical results predicted these flow characteristics well.

Impacts of Chemical Heterogeneities in Landfill Subsurface Formations on the Transport of Leachate (매립지반의 화학적 불균질성이 침출수 이동에 미치는 영향)

  • Lee Kun-Sang
    • Journal of Soil and Groundwater Environment
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    • v.11 no.5
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    • pp.1-8
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    • 2006
  • The objective of this study is to assess impacts of sorption heterogeneity on the transport of leachate leaked from unlined landfill sites and is accomplished by examining the results from a series of Monte-Carlo simulations. For random distribution coefficient ($K_{d}$) fields with four different levels of heterogeneity ranging from homogeneous to highly heterogeneous, the transport of leachate was investigated by linking a saturated flow model with a contaminant transport model. Impacts of a chemical heterogeneity were evaluated using point statistics values such as mean, standard deviation, and coefficient of variation of the concentration obtained at monitoring wells from 100 Monte-Carlo trials. Inspection of point statistics shows that the distribution of distribution coefficient in the landfill site proves to be an important parameter in controlling leachate concentrations. In comparison to homogeneous sorption, heterogeneous $K_{d^-}$ fields produce the variability in the leachate concentration for different realizations. The variability increases significantly as the variance in the $K_{d^-}$ field and the travel time between source and monitoring well increase. These outcomes indicate that use of a constant homogeneous $K_{d}$ value for predicting the transport of leachate can result in significant error, especially when variability in $K_{d}$ is high.

Impacts of Combined Hydrogeological and Chemical Heterogeneities on the Transport of Leachate through Landfill Sites (수리지질학적, 화학적 특성의 복합 불균질성이 매립지반 내 침출수 이동에 미치는 영향)

  • Lee, Kun-Sang
    • Journal of Korean Society of Environmental Engineers
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    • v.31 no.4
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    • pp.300-307
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    • 2009
  • The transport of landfill leachate in the subsurface formations of unlined landfill sites is considered. The impacts of hydrogeological and chemical heterogeneities on the leachate transport are assessed by examining the results from a series of Monte-Carlo simulations. The landfill system simulated in this study is hypothetically represented with three levels of spatial variability for the hydrogeological and chemical parameter; (1) homogeneous hydraulic conductivity (K) and distribution coefficient ($K_d$), (2) K heterogeneity only, and (3) combined heterogeneities of K and $K_d$. To calculate the transport of leachate through negatively-correlated random hypothetical K-$K_d$ fields generated using geostatistical input parameters, a saturated flow model is linked with a contaminant transport model. Point statistic values such as mean, standard deviation, and coefficient of variation of the concentration were obtained from 100 Monte-Carlo trials. Results of point statistics show that the heterogeneities of K and $K_d$ in the landfill site prove to be an important parameter in controlling leachate concentrations. Consideration of combined K and $K_d$ heterogeneities results in enhancing the variability of contaminant transport. The variability in the leachate concentration for different realizations also increases as the distance between source and monitoring well increase.

CFD (Computational Fluid Dynamics) Study on Partial-Load Combustion Characteristics of a 4-Step-Grate Wood Pellet Boiler (4단 화격자 목재 펠릿 보일러의 부분부하 연소해석)

  • Ahn, Joon;Jang, Jun Hwan
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.38 no.4
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    • pp.365-371
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    • 2014
  • A numerical simulation was conducted for the combustion chamber of a 4-step grate-firing boiler for wood pellet fuel. The flame is extended to the exit of combustion chamber, which is reproduced by present numerical method based on a homogeneous reaction model. Flow field from the simulation shows a strong recirculation flow at the upstream corner of the chamber, along which the flame is extended to the exit. These combustion and flow characteristics remain unchanged for partial load operations, which suggest modification of the combustion chamber structure rather than resizing should be effective to improve combustion characteristics. Possible modifications for combustion chamber are suggested such as relocating its exit, increasing the number of grate steps or installing internals such as guide baffles.

Modelling of Fault Deformation Induced by Fluid Injection using Hydro-Mechanical Coupled 3D Particle Flow Code: DECOVALEX-2019 Task B (수리역학적연계 3차원 입자유동코드를 사용한 유체주입에 의한 단층변형 모델링: DECOVALEX-2019 Task B)

  • Yoon, Jeoung Seok;Zhou, Jian
    • Tunnel and Underground Space
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    • v.30 no.4
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    • pp.320-334
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    • 2020
  • This study presents an application of hydro-mechanical coupled Particle Flow Code 3D (PFC3D) to simulation of fluid injection induced fault slip experiment conducted in Mont Terri Switzerland as a part of a task in an international research project DECOVALEX-2019. We also aimed as identifying the current limitations of the modelling method and issues for further development. A fluid flow algorithm was developed and implemented in a 3D pore-pipe network model in a 3D bonded particle assembly using PFC3D v5, and was applied to Mont Terri Step 2 minor fault activation experiment. The simulated results showed that the injected fluid migrates through the permeable fault zone and induces fault deformation, demonstrating a full hydro-mechanical coupled behavior. The simulated results were, however, partially matching with the field measurement. The simulated pressure build-up at the monitoring location showed linear and progressive increase, whereas the field measurement showed an abrupt increase associated with the fault slip We conclude that such difference between the modelling and the field test is due to the structure of the fault in the model which was represented as a combination of damage zone and core fractures. The modelled fault is likely larger in size than the real fault in Mont Terri site. Therefore, the modelled fault allows several path ways of fluid flow from the injection location to the pressure monitoring location, leading to smooth pressure build-up at the monitoring location while the injection pressure increases, and an early start of pressure decay even before the injection pressure reaches the maximum. We also conclude that the clay filling in the real fault could have acted as a fluid barrier which may have resulted in formation of fluid over-pressurization locally in the fault. Unlike the pressure result, the simulated fault deformations were matching with the field measurements. A better way of modelling a heterogeneous clay-filled fault structure with a narrow zone should be studied further to improve the applicability of the modelling method to fluid injection induced fault activation.

Fracture Developing History and Density Analysis based on Grid-mapping in Bonggil-ri, Gyeongju, SE Korea (경주시 봉길리 지역의 단열발달사 및 단열밀도 해석)

  • Jin, Kwang-Min;Kim, Young-Seog
    • The Journal of Engineering Geology
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    • v.17 no.3
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    • pp.455-469
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    • 2007
  • The study area, Bonggil-ri, Gyeongju, SE Korea, is composed of Cretaceous sedimentary rocks, and Tertiary igneous rocks and dykes. A research on fracture developing history and density distribution was carried out on well exposed Tertiary granites. The fractures developed in this area have the following sequence; NW-SE trending duo-tile shear bands (set a), NNW-SSE trending extensional fractures (set d), WNW-ESE trending extensional or normal fractures (set b), NE-SW trending right-lateral fractures (set c), WNW-ESE trending reverse fault reactivated from normal faults (set e) and NW-SE trending left-lateral faults reactivated from shear bands (set a) under brittle condition. According to the result of fracture density analysis, the fracture density in this area depends on rock property rather than rock age, and also higher fracture density is observed around fault damage zones. However, this high fracture density may also be related to the cooling process associated with dyke intrusion as well as rock types and fault movement. Regardless of the reason of the high fracture density, high fracture density itself contributes to fluid flow and migration of chemical elements.

The Roles of Shop Owners in Boosting Conventional Markets (상권활성화에 있어서 상업자의 역할에 관한 연구)

  • Park, Seung-Je
    • Journal of Distribution Science
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    • v.9 no.4
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    • pp.93-102
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    • 2011
  • With the increasing interest in boosting conventional markets, many authors have paid considerable attention to the roles of shop owners, store image improvement, and how to attract or maintain customers. Nevertheless, it is not easy to find papers related to the relationship between shop owners and their contribution to trading areas, directly or indirectly, in the academic world. Accordingly, research for answering the following question has been initiated: what kind of roles do shopkeepers should play in revitalizing poor conventional markets? Based on the previous studies focusing on enhancing traditional markets, this research was approached from the new insights that have been obtained concerning how to boost conventional markets, that is, from the perspectives of a shop owner and a trader. Therefore, this research aims at identifying some resolutions associated with the roles of shop owners to enhance a shopping district in a specific area, classifying their business roles into a few categories, depending on the degree of their participation in improving the shopping environment. Compared with previous studies focusing on emphasizing the importance of improving customer services from a shopkeeper's perspective, this research provides a new insight as far as how to boost conventional markets. It is, furthermore, necessary to note how market participants, particularly shop owners as they are the key players, can contribute to rebuilding their business area together with their customers. As a research technique for effectively achieving the research goal, the authors adopted a documentation methodology based on a large amount of the existing literature for studying how to rebuild traditional markets. Concerned about the ways to revitalize conventional markets, many authors have proposed a variety of strategies, and have suggested more detailed action plans from a practitioner's perspective. By analyzing these research results, the authors will have accomplished the research aim. Rather than simply identifying the roles of shop owners, the author found that they had to understand their social contribution for enhancing their trading areas, as well as their functional roles, in forming a regional society. The conventional market should be, thus, regarded as the place to share regional culture. Consequently, the authors draw some conclusions from the research results. In order to answer the above question, it was found that the roles of shop owners have been considered as one of the most important ways for revitalizing traditional markets. With respect to their roles, it is evident that their business activities are closely related to the improvement of the trading area in terms of sociality, regional development, and market revitalization, by selling products or services to the customers visiting that area. In a word, this implies that shop owners have to actively take part in boosting conventional markets as a core player. Although the authors have properly achieved the research aim, this study has a limitation, like most other research, in adopting a documentation method. Because the research is based on existing data results provided by the prior research conducted a long time ago, whether the research findings are applicable in a contemporary market should be re-examined in future research from a practitioner's perspective, rather than from an academic's perspective.

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Application of WEP Model to the Cheonggecheon Watershed (청계천 유역에 대한 WEP 모형의 적용)

  • Noh, Seong Jin;Kim, Hyeon Jun;Cheong, Il Moon;Jang, Cheol Hee;Kim, Dong Pil
    • Proceedings of the Korea Water Resources Association Conference
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    • 2004.05b
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    • pp.148-152
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    • 2004
  • 본 연구에서는 물순환의 재생이나 보전에 필수적인 유역 물순환의 정량화와 유역변화의 영향예측을 위해 개발된 WEP (Water and Energy Transfer Process) 모형의 국내 유역에 내한 적용성을 검토하고, 청계천 유역의 물순환 양상을 모의하였다. WEP 모형은 복잡한 토지이용이 이루어지고 있는 도시하천 유역에 내한 물순환의 정량화를 목적으로 일본의 토목연구소 (PWRI; Public Works Research Institute), 과학기술진흥사업단, Jia 박사 등에 의해 공동으로 개발되었으며 지표면 및 비포화 토양층의 물${\cdot}$열 플럭스 계산, 하도흐름의 추적계산 및 지하수 유동계산, 격자내 토지이용의 불균질성 반영 등이 가능한 물리적인 기반의 공간 분포형 모형 (Physically Based Spatially Distributed)이다. 모형을 적용한 청계천 유역 (유로연장 13.75 km, 유역 면적 $50.96km^2$)은 전체 토지이용중 도시지역이 $75.9\%$를 차지하고, 유역내 인구가 120만명에 이르는 도시유역으로 높은 불투수 면적비율, 인공계 물순환 요소의 영향 등의 도시 유역 특성이 물순환의 구조 전반에 미치는 영향에 대한 연구가 부족하였다. WEP 모형 적용 결과, 모의 기간 동안의 하천 유출량은 실측치에 근사한 값을 나타내었으며 유역의 물순환 양상을 모의할 수 있었다. 청계천 유역은 전형적인 도시 유역의 특성을 보여주었는데, 강우시의 직접유출이 크고, 강우의 유출에 대한 반응이 빠르며, 증발산의 경우는 산림지역보다 도시지역이 상대적으로 적은 것으로 분석되었다. 이번 연구를 통하여 WEP 모형이 유역 물순환 해석에 적절한 모형임을 확인할 수 있었으면, 향후 청계천 유역의 물리적 특성에 대한 매개변수와 인공계 물순환 자료의 보완을 통해 보다 향상된 모의가 가능할 것으로 판단된다. 하였던 Cd과 Mg이 Ca 및 Ca과 vitamin D의 동시(同時) 급여(給與)로 감소(減少)하였고 Cu는 전체적(金體的)으로 변화(變化)가 없었으며 Zn은 Cd 급여(給與)로 감소(減少)하였으나 Ca과 vitamin D의 급여(給與)에 의하여 증가(增加)하였고 Ca은 Ca과 viamin D의 급여(給輿)로 유의(有意)하게 증가(增加)하였다. 신장(腎臟)중의 무기질(無機質) 함량(含量)은 Cd급여(給輿)로 Cu, Mg은 감소(滅少)하였으나 Ca, Zn은 변화(變化)가 없었고 Ca 및 Ca과 Vitamin D의 급여(給與)로 Cd, CU, Zn은 증가(增加)하였다.ce area)는 수술 전100.8$\pm$25.6 mm/$m^{2}$에서 79.3$\pm$ 15.8 mm/$m^{2}$로 감소한 소견을 보였다. 승모판 성형술은 전 승모판엽 탈출증이 있는 두 환아에서 동시에 시행하였다. 수술 후 1년 내 시행한 심초음파에서 모든 환아에서 단지 경등도 이하의 승모판 폐쇄 부전 소견을 보였다. 수술 후 조기 사망은 없었으며, 합병증으로는 유미흉이 한 명에서 있었다. 술 후 10개월째 허혈성 확장성 심근증이 호전되지 않아 Dor 술식을 시행한 후 사망한 예를 제외한 나머지 6명은 특이 증상 없이 정상 생활 중이다 결론: 좌관상동맥 페동맥이상 기시증은 드물기는 하나, 영유아기에 심근경색 및 허혈성 심근증 또는 선천성 승모판 폐쇄 부전등을 초래하는 심각한 선천성 심질환이다. 그러나 진단 즉시 직접 좌관상동맥-대동맥 이식술로 수술적 교정을 해줌으로써 좋은 성적을 기대할 수 있음을 보여주었다.특히 교사들이 중요하게 인식하는 해방적 행동에 대한 목표를 강조하여 적용할 필요가 있음을 시사하고 있다.교하여 유의한 차이가 관찰되지 않았다. 또한 HSP 환자군에서도 $IL1RN^{*}2$ allele 빈도와 carriage

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